Many individuals in the field are frustrated by the slow progress getting PDT established in mainstream clinical practice. The five key reasons are: 1. Lack of adequate evidence of safety and efficacy and optimization of dosimetry. These are fundamental. The number of randomized controlled studies is still small. For some cancer applications, it is difficult to get patients to agree to be randomised, so different approaches must be taken. Anecdotal results are not acceptable to sceptics and regulators. 2. The regulatory processes. The rules get more complex every day, but there is no choice, they must be met. The full bureaucratic strength of the pharmaceutical industry is needed to address these issues. 3. Conservatism of the medical profession. Established physicians are reluctant to change practice, especially if it means referring patients to different specialists. 4. Lack of education. It is amazing how few physicians have even heard of PDT and many that have, are sceptical. The profile of PDT to both the medical profession and the general public needs to be raised dramatically. Patient demand works wonders! 5. Money. Major investment is required to run clinical trials. Pharmaceutical companies may see PDT as a threat (eg reduced market for chemotherapy agents). Licensed photosensitisers are expensive. Why not reduce the price initially, to get the technique established and stimulate demand? PDT has the potential for enormous cost savings for health service providers. With appropriate motivation and resources these problems can be addressed. Possible routes forward will be suggested.

Photodynamic techniques such as photodynamic diagnosis (PDD), fluorescence guided tumor resection (FGR) and photodynamic therapy (PDT) are currently undergoing intensive clinical investigations as adjunctive treatment for malignant brain tumours. This review provides an overview on the current clinical data and trials as well as on photosensitisers, technical developments and indications for photodynamic application in Neurosurgery. Furthermore new developments and clinical significance of FGR for neurosurgery will be discussed. Over 1000 patients were enrolled in various clinical phase I/II trials for PDT for malignant brain tumours. Despite various treatment protocols, variation of photosensitisers and light dose there is a clear trend towards prolonging median survival after one single PDT as compared to conventional therapeutic modalities. The median survival after PDT for primary glioblastoma multiforme WHO IV was 19 months and for recurrent GBM 9 months as compared to standard convential treatment which is 15 months and 3 months, respectively. FGR in combination with adjunctive radiation was significantly superior to standard surgical resection followed by radiation. The combination of FGR/PDD and intraoperative PDT increased significantly survival in recurrent glioblastoma patients. The combination of PDD/ FGR and PDT offers an exciting approach to the treatment of malignant brain tumours "to see and to treat." PDT was generally well tolerated and side effects consisted of occasionally increased intracranial pressure and prolonged skin sensitivity against direct sunlight. This review covers the current available data and draws the future potential of PDD and PDT for its application in neurosurgery.

Photodynamic Therapy (PDT) generates singlet oxygen (¹O₂) which oxidizes biomolecules in the immediate vicinity of its formation. The phthalocyanine photosensitizer Pc 4 localizes to mitochondria and endoplasmic reticulum, and the primary targets of Pc 4-PDT are expected to be lipids and proteins of those membranes. The initial damage then causes apoptosis in cancer cells via the release of cytochrome c (Cyt-c) from mitochondria into the cytosol, followed by the activation of caspases. That damage also triggers the induction of autophagy, an attempt by the cells to eliminate damaged organelles, or when damage is too extensive, to promote cell death. Cyt-c is bound to the cytosolic side of the mitochondrial inner membrane through association with cardiolipin (CL), a phospholipid containing four unsaturated fatty acids and thus easily oxidized by ¹O₂ or by other oxidizing agents. Increasing evidence suggests that oxidation of CL loosens its association with Cyt-c, and that the peroxidase activity of Cyt-c can oxidize CL. In earlier studies of Cyt-c in homogeneous medium by MALDI-TOF-MS and LC-ESI-MS, we showed that ¹O₂ generated by Pc 4-PDT oxidized histidine, methionine, tryptophan, and unexpectedly phenylalanine but not tyrosine. Most of the oxidation products were known to be formed by other oxidizing agents, such as hydroxyl radical, superoxide radical anion, and peroxynitrite. However, two products of histidine were unique to ¹O₂ and may be useful for reporting the action of ¹O₂ in cells and tissues. These products, as well as CL oxidation products, have now been identified in liposomes and mitochondria after Pc 4-PDT. In mitochondria, the PDT dose-dependent oxidations can be related to specific changes in mitochondrial function, Bcl-2 photodamage, and Cyt-c release. Thus, the role of PDT-generated ¹O₂ in oxidizing Cyt-c and CL and the interplay between protein and lipid targets may be highly relevant to understanding one mechanism for cell killing by PDT.

During the irradiation of photosensitized cells, reactive oxygen species (ROS) are generated leading to a variety of effects including apoptosis and autophagy. These responses can occur within minutes after irradiation. Apoptosis is an irreversible pathway to death that can be triggered by release of cytochrome c from mitochondria. Autophagy is a recycling process that can occur as a result of Bcl-2 photodamage or as a response to organelle disruption. We have reported that autophagy is associated with a 'shoulder' on the PDT dose-response curve. Although predominantly a survival pathway, autophagy can also play a role in cell death if cells attempt an excessive amount of recycling, beyond their ability to repair photodamage. Recent studies have been directed toward assessing the role of different ROS in the immediate response to PDT. While singlet oxygen is considered to be the major phototoxic ROS, it appears that catalase activity is also a determinant of the apoptotic response and that H₂O₂^•OH can amplify the effects of singlet oxygen. An early response to PDT also involves inhibition of membrane trafficking systems related to the endocytic pathway. The extent and nature of these early responses appear to be among the determinants of subsequent tumor eradication.

In photodynamic therapy (PDT), visible light activates a photosensitizing drug added to a tissue, resulting in singlet oxygen formation and cell death. Assessed by confocal microscopy, the photosensitizer phthalocyanine 4 (Pc 4) localizes primarily to mitochondrial membranes in cancer cells, resulting in mitochondria-mediated cell death. A Pc 4 derivative, Pc 181, accumulates into lysosomes. In comparison to Pc 4, Pc 181 was a more effective photosensitizer promoting killing cancer cells after PDT. The mode of cell death after Pc 181-PDT is predominantly apoptosis, and pancaspase and caspase-3 inhibitors prevent onset of the cell death. To assess further how lysosomes contribute to PDT, we monitored cell killing of A431cells after PDT in the presence and absence of bafilomycin, an inhibitor of the acidic vacuolar proton pump that collapses the pH gradient of the lysosomal/endosomal compartment. Bafilomycin by itself did not induce toxicity but greatly enhanced Pc 4-PDT-induced cell killing. In comparison to Pc 4, less enhancement of cell killing by bafilomycin occurred after Pc 181-PDT at photosensitizer doses producing equivalent cell killing in the absence of bafilomycin. These results indicate that lysosomal disruption can augment PDT with Pc 4, which targets predominantly mitochondria, but less so after PDT with Pc 181, since Pc 181 already targets lysosomes.

Anti-tumor immunity is stimulated after PDT due a number of factors including: the acute inflammatory response caused by PDT, release of antigens from PDT-damaged tumor cells, priming of the adaptive immune system to recognize tumor-associated antigens (TAA), and induction of heat-shock proteins. The induction of specific CD8+ T-lymphocyte cells that recognize major histocompatibility complex class I (MHC-I) restricted epitopes of TAAs is a highly desirable goal in cancer therapy as it would allow the treatment of tumors that may have already metastasized. The PDT killed tumor cells may be phagocytosed by dendritic cells (DC) that then migrate to draining lymph nodes and prime naïve T-cells that recognize TAA epitopes. We have carried out in vivo PDT with a BPD-mediated vascular regimen using a pair of BALB/c mouse colon carcinomas: CT26 wild type expressing the naturally occurring retroviral antigen gp70 and CT26.CL25 additionally expressing beta-galactosidase (b-gal) as a model tumor rejection antigen. PDT of CT26.CL25 cured 100% of tumors but none of the CT26WT tumors (all recurred). Cured CT26.CL25 mice were resistant to rechallenge. Moreover mice with two bilateral CT26.CL25 tumors that had only one treated with PDT demonstrated spontaneous regression of 70% of untreated contralateral tumors. T-lymphocytes were isolated from lymph nodes of PDT cured mice that recognized a particular peptide specific to b-gal antigen. T-lymphocytes from LN were able to kill CT26.CL25 target cells in vitro but not CT26WT cells as shown by a chromium release assay. CT26.CL25 tumors treated with PDT and removed five days later had higher levels of Th1 cytokines than CT26 WT tumors showing a higher level of immune response. When mice bearing CT26WT tumors were treated with a regimen of low dose cyclophosphamide (CY) 2 days before, PDT led to 100% of cures (versus 0% without CY) and resistance to rechallenge. Low dose CY is thought to deplete regulatory T-cells (Treg, CD4+CD25+foxp3+) and potentiate immune response after PDT in the case of tumors that express self-antigens. These data suggest that PDT alone will stimulate a strong immune response when tumors express a robust antigen, and in cases where tumors express a self-antigen, T-reg depletion can unmask the immune response after PDT.

Epigenetic mechanisms, which involve DNA methylation and histone modifications, result in the heritable silencing of genes without a change in their coding sequence. However, these changes must be actively maintained after each cell division rendering them a promising target for pharmacologic inhibition. DNA methyltransferase inhibitors like 5-aza-deoxycytidine (5-aza-dC) induce and/or up-regulate the expression of MAGE-type antigens in human and mice cancer cells. Photodynamic therapy (PDT) has been shown to be an effective locally ablative anti-cancer treatment that has the additional advantage of stimulating tumor-directed immune response. We studied the effects of a new therapy that combined the demethylating agent 5-aza-dC with PDT in the breast cancer model 4T1 syngenic to immunocompetent BALB/c mice. PDT was used as a locally ablating tumor treatment that is capable of eliciting strong and tumor directed immune response while 5-aza-dC pretreatment was used promote de novo induction of the expression of P1A.protein. This is the mouse homolog of human MAGE family antigens and is reported to function as a tumor rejection antigen in certain mouse tumors. This strategy led to an increase in PDT-mediated immune response and better treatment outcome. These results strongly suggest that the MAGE family antigens are important target for PDT mediated immune response but that their expression can be silenced by epigenetic mechanisms. Therefore the possibility that PDT can be combined with epigenetic strategies to elicit anti-tumor immunity in MAGE-positive tumor models is highly clinically significant and should be studied in detail.

Our laboratory has constructed a custom fluorescence microendoscope for detecting and monitoring tumor nodules in a mouse model of metastatic ovarian carcinoma (OVCA). The microendoscope is being applied for tumor recognition and for quantifying tumor burden reduction following photodynamic therapy (PDT). Benzoporphyrin derivative monoacid ring A (BPD-MA), a photosensitizing agent for PDT, is administered to the mice and imaged with the microendoscope prior to PDT. BPD-MA fluorescence is a convenient means for locating tumor sites and quantifying tumor burden (despite the fact that BPD-MA is a non-targeted contrast agent). The miniature, flexible microendoscope probe is delivered via a 14-gauge catheter for imaging metastases along the outer surfaces of the internal organs and the inner walls of the peritoneal cavity. The minimal invasiveness of this approach facilitates frequent imaging of the mice in order to monitor cancer progression and treatment response. We present promising data for intravital imaging of treatment response following PDT and new developments in the microendoscope instrumentation for improved image quality.

Photodynamic therapy with porfimer sodium (PS) is a treatment option for high grade dysplasia associated with Barrett's esophagus. This study sought to investigate the optical properties of Barrett's dysplasia that may be useful in light dosimetry planning and to determine the effect of PS on tissue absorption and scattering. Fiber optic reflectance spectra were collected before and 48 hours after administration of 2 mg/kg PS. Mucosal biopsies were collected at the same locations. According to Monte Carlo analysis, the fiber optic probe sampled only the mucosal layer. A mathematical fit of the reflectance spectra was performed as a function of blood volume fraction, oxygen saturation and scattering. The average calculated blood volume was 100% higher in Barrett's tissue than normal esophageal tissue. The average scattering slope from 620 to 750 nm was 26% higher for Barrett's dysplasia than normal esophageal tissue, indicating an increase in the size of scattering particles. The difference in the scattering amplitude was not statistically significant, suggesting no significant increase in the number of scattering particles. PS tissue content was determined with extraction methods. Changes in the scattering slope due to PS sensitization were observed; however they were not proportional to the extracted PS concentration.

Type 2 photoreactions are singlet oxygen (¹O₂) mediated. This singlet oxygen will de activate by reacting with a number of targets and produce ROS and peroxides that will in turn give Reactive Oxygen Species (ROS). In order to verify whether sera had the same capability to do so we provoked a photoreaction using Rose Bengal (RB) added to sera of 53 healthy donors and at the end of light delivery 2' -7' dichlorofluorescin (DCFH) had been added. In order to avoid any optical artefact we analysed the influence of haemolysis on the fluorescent 2' -7' dichlorofluorescin (DCF) induced by oxidising species. Reactivity to singlet oxygen was slightly different between men and women, varied slightly with age and platelet number. It was remarkably stable over a large period of time and thus represents a characteristic of each serum. Studies are in progress to verify whether ROS dependent diseases would impair this reactivity to singlet oxygen.

Objectives: Basal cell carcinomas (BCCs) are the most common skin cancers, and incidence rates are still rising. Photodynamic Therapy (PDT) with mTHPC (Foscan®) has shown to be a promising alternative to other treatments with good cosmetic results. This study was performed to determine optimal treatment parameters for this indication. Methods: 117 patients with a total of 460 BCCs received mTHPC-PDT. The treatment parameters were varied as follows: Foscan® dose 0.03 - 0.15 mg/kg, drug-light interval (DLI) 1 - 96 hours, total energy density 20 - 120 J/cm2. The clinical outcomes were assessed 8 weeks after PDT following WHO guidelines. Results: The rate of complete remissions (CR) was 96.7% and the general cosmetic outcome rated very good. In the largest subgroup (n=80) with low-dose mTHPC (0.05 mg/kg mTHPC; 48 hours DLI; 50 J/cm2 total energy density), a CR rate of 100% was accomplished. Minor changes of the parameters (0.04 mg/kg mTHPC or 24 hours DLI) yielded similar results. Side effects were encountered in 52 out of 133 PDT sessions. They were more common in patients who had received high drug doses (0.06 - 0.15 mg/kg) and comprised pain and phototoxic reactions. 3 patients developed severe sunburns with subsequent scarring at the injection site following sunlight exposure 2-3 weeks after mTHPC administration. Conclusions: The data suggests that low-dose mTHPC-PDT is an effective treatment option for BCCs. If sensibly applied, it is well tolerated and provides mostly excellent cosmetic results. The evaluation of long term results is still to be undertaken.

Fluorescence guided surgical resection is based on the basic principle that photosensitizers are preferentially taken up and retained by cancer cells and the these sensitizers absorb light in one band of the light spectrum and release the energy as fluorescence that can be visualised in a different band of the spectrum. This study reports fluorescence outcome of 110 consecutive intracranial tumors to identify its potential benefits during fluorescence guided resection (FGR). The specificity of this technique was very high with no false positive results. Its sensitivity varied from 83.7% in brain lung metastasis to 85.7% in glioblastomas. A wide range of other intracranial tumors were also studied but the numbers in each of these subgroups were small to deduct its usefulness. However, grade III astrocytomas, primary cerebral lymphoma and meningiomas fluoresced very well in all patients. FGR would be therefore very useful aid during a wide range of intracranial tumor surgery with the advantages of specificity, high sensitivity and would not be affected by brain shift and tumor removal. The limitations of this technique were that the sensitivity was not 100% and it would be possible to miss 15% of tumors, blood can also obscure the fluorescence and it would be a problem in vascular tumors, and photo bleaching can reduce the fluorescence.

There is a need for better management strategies to improve survival and quality of life in patients with biliary tract cancer (BTC). We compared treatment outcomes in 321 patients (median age 65 years, range 29-102; F:M; 1:1) with a final diagnosis of BTC (cholangiocarcinoma n=237, gallbladder cancer n=84) seen in a tertiary referral cancer centre between 1998-2007. Of 89 (28%) patients who underwent surgical intervention with curative intent, 38% had R0 resections and had the most favourable outcome, with a 3 year survival of 57%. Even though PDT patients had more advanced clinical T-stages, their survival was similar to those treated with attempted curative surgery which resulted in R1/2 resections (median survival 12 vs. 13 months, ns). In a subgroup of 36 patients with locally advanced BTC treated with PDT as part of a prospective phase II study, the median survival was 12 (range 2-51) months, compared with 5 months in matched historical controls treated with stenting alone (p < 0.0001). In this large UK series, long-term survival with BTC was only achieved in surgical patients with R0 resection margins. Palliative PDT resulted in similar survival to those with curatively intended R1/R2 resections.

Pancreatic cancer (PanCa) has a poor prognosis with a 5-year survival rate of only 5%. Photodynamic therapy (PDT) has shown promising results in treating PanCa. Mechanism-based combinations with PDT have enhanced treatment outcome. Agents tested with PDT include Avastin, an antibody against vascular endothelial growth factor (VEGF) which is approved for treating various cancers. Simultaneous delivery of drugs in nano-constructs could improve the treatment response of mechanism based combination therapies. Here, we investigate the effect of neutralizing VEGF using nanotechnology for the delivery of Avastin in combination with PDT. For this we used a construct called "nanocells" in which the photosensitizer was trapped inside polymer nanoparticles and these, with Avastin, were then encapsulated inside liposomes. In vitro, nanocells containing Avastin (NCA) significantly enhanced cytotoxicity in PanCa cells. NCA based PDT also significantly improved treatment response in mice that were orthotopically implanted with PanCa. Avastin delivered extracellularly in combination with PDT did not show any improvement. Here we propose a new paradigm for Avastin-based therapy by combining intracellular delivery of the antibody and PDT using nanotechnology for treating PanCa.

Since the first report by Agarwal et al in 1991 on apoptotic induction by photodynamic therapy (PDT) with chloroaluminium phthalocyanine a large number of papers have come out to show that PDT can induce cell death through apoptosis. This finding may provide potential clinical impact on, for example, those tumor cells resistant to any cancer therapy. The present paper briefly reviews apoptosis with emphasis on PDT-induced apoptosis with hexaminolevulinate.

New approaches to PDT using multifunctional 5-aminolevulinic acid (ALA) based prodrugs activating mutual routes of toxicity are described. We investigated the mutual anti-cancer activity of ALA prodrugs which upon metabolic hydrolysis by unspecific esterases release ALA, formaldehyde or acetaldehye and the histone deacetylase inhibitor (HDACI) butyric acid. The most potent prodrug in this study was butyryloxyethyl 5-amino-4-oxopentanoate (AN-233) that stimulated a rapid biosynthesis of protoporphyrin IX (PpIX) in human glioblastoma U-251 cells and generated an efficient photodynamic destruction. AN-233 induced a considerable high level of intracellular ROS in the cells following light irradiation, reduction of mitochondrial activity, dissipation of the mitochondrial membrane potential resulting in necrotic and apoptotic cell death. The main advantage of AN-233 over ALA stems from its ability to induce photodamage at a significantly lower dose than ALA.

Photodynamic therapy (PDT) using porphyrin precursors is commonly used in dermatology. Evidence indicates that good clinical outcomes (associated with excellent cosmesis) can be achieved in superficial precancers and basal cell carcinoma (BCC), however, efficacy appears less favorable for thicker nodular BCC (nBCC) unless multiple PDT treatment cycles are performed. Enhancement is therefore required if nBCC lesions are to be treated effectively with a single PDT treatment. The most common technique currently being routinely employed clinically is the use of aminolevulinic acid (ALA) esters (usually methyl (MAL) or hexyl (HAL)). Standard dermatological PDT employing these porphyrin precursors already manipulates the normal heme biosynthesis pathway resulting in a temporary accumulation of the natural photosensitizer, protoporphyrin IX (PpIX). Further manipulation using iron chelating agents is possible however. In normal and malignant human cells in vitro, the novel iron chelating agent CP94 produced greater PPIX fluorescence when administered with ALA or MAL than either congener produced alone. CP94 was also significantly more effective than the clinically established iron chelating agent desferrioxamine (DFO). Topical application of ALA+CP94 to clinical nBCC lesions was a simple and safe treatment modification which produced a significant increase in clinical clearance when CP94 was included in the cream.

Protoporphyrin IX (PpIX) synthesized endogenously from 5-aminolevulinic acid (ALA), is effluxed from cells expressing the ATP-dependent transporter ABCG2. Side population (SP) cells (named for their low red/blue fluorescence distribution in flow cytometry plots with ABCG2 substrates such as Hoechst) are postulated to contain cancer stem cells (CSC). The SP in U87 (human gliblastoma cell line) were more resistant to ALA-PDT than NON-SP cells. Inhibiting ABCG2 activity with the tyrosine kinase inhibitor imatinib mesylate (IM, Gleevec) during incubation with ALA increased PpIX in the SP by preventing its efflux and decreased the SP after subsequent PDT, enhancing phototoxicity. Evasion of SP cells from ALA-PDT could cause tumor recurrence from CSC. Manipulation of ABCG2 levels on the SP with small molecule modulators may be a potential strategy for enhancing PDT by decreasing the amount of substrate photosensitizer extruded from cells and lowering the threshold for phototoxicity.

superficial lesions, such as actinic keratosis. In addition, photodynamic antimicrobial chemotherapy (PACT) is attracting increasing interest for the treatment of infection. However, delivery strategies for topical PDT and PACT are still based on application of rather simplistic cream and solution formulations, with little consideration given to thermodynamics, targeting or the physicochemical properties of the active agent. Purpose-designed dosage forms for topical delivery of aminolevulinic acid or its esters include creams containing penetration enhancers and/or iron chelators, pressure sensitive patches and bioadhesive patches. Such systems aim to enhance drug delivery across the stratum corneum and keratinised debris overlying neoplastic lesions and improve subsequent protoporphyrin IX (PpIX) production. The alternative to using porphyrin precursors is the use of pre-formed photosensitisers. However, owing to their relatively high molecular weights, conventional topical application is not appropriate. Innovative strategies, such as the use of needle-free injections and microneedle arrays, bypass the stratum corneum, enabling rapid and targeted delivery not only porphyrin precursors but also pre-formed photosensitisers. This presentation will review drug delivery work published to date in the fields of PDT and PACT. In addition, the benefits of employing the latest advances in pharmaceutical technology will be highlighted.

We have been investigating PDT with 5 aminolaevulinic acid (ALA) for the treatment of high grade dysplasia (HGD) in Barrett's oesophagus (BO) for over a decade. This drug has inherent advantages over porfimer sodium (Photofrin), the current approved photosensitiser in the UK and USA, which causes strictures in 18-50% and light sensitivity for up to three months. ALA has a lower rate of oesophageal strictures due to its preferential activity in the mucosa, sparing the underlying muscle, and patients are only light sensitive for 1-2 days. Within a randomised controlled trial, we demonstrated that an ALA dose of 60mg/kg activated by 1000J/cm red laser light is the most effective. Using these values we achieved complete reversal of HGD at 1 year in 89% of 27 patients. A randomised controlled trial of ALA vs porfimer sodium PDT for HGD is currently under way with end points of efficacy and safety. 50 of 66 patients have been recruited. Preliminary data suggest ALA PDT is safer with a trend to higher efficacy. Late relapse can occur in 20% of patients. New prognostic markers, in particular aneuploidy, are helping us to identify and target patients at risk of late relapse. Furthermore optical biopsy techniques such as elastic scattering spectroscopy (ESS) may allow detection of nuclear abnormalities in vivo and enable us to target areas of interest whilst reducing sampling error. PDT faces new challenges for the treatment of HGD in BO, with the recent introduction of balloon based radiofrequency ablation. This technique appears simpler and as effective as PDT, but follow up is currently short and long term safety data is lacking. In our experience ALA PDT is currently the most effective minimally invasive treatment for HGD in BO. This work was undertaken at UCLH/UCL who received a proportion of funding from the Department of Health's NIHR Biomedical Research Centres funding scheme.

Background and Objective: We have evaluated the ability of ALA-mediated PDT to selectivly open the BBB in rats. This will permit access of chemotherapeutic agents to brain tumor cells remaining in the resection cavity wall, but limit their penetration into normal brain remote from the site of illumination. Study Design/Materials and Methods: ALA-PDT was performed on non-tumor bearing inbred Fischer rats at increasing fluence levels. Contrast T1-weighted high field (3 T) magnetic resonance imaging (MRI) scans were used to monitor the degree of BBB disruption. Results: PDT at increasing fluence levels between 9 and 17 J demonstrated an increasing contrast flow rate. The BBB was found to be disrupted 2 h following PDT and 80 - 100 % restored 72 h later at the lowest fluence level. No effect on the BBB was observed if 26 J of light was given in the absence of ALA. Conclusion: ALA-PDT was highly effective in opening the BBB in a localized region of the brain. The degradation of the BBB was temporary in nature at fluence levels of 9 J, opening rapidly following treatment and significantly restored during the next 72 h. No signs of permanent tissue damage were seen on histological sections at this fluence level.

A summary of clinical trials employing photodynamic diagnosis (PDD) and photodynamic therapy (PDT) for the diagnosis and treatment of brain malignancies is presented. Intra-cavity PDT has been performed within the surgical cavity following FGR, employing oral administration of 5-aminolevulinic acid (5-ALA), either targeting fluorescing tissue regions that were not removed during FGR due to safety reasons (referred to as focal PDT, n=20) or illuminating the entire resection cavity (referred to as integral PDT, n=9). Both approaches proved technically feasible and safe. Spectroscopic measurements performed pre-, during and post-PDT revealed Protoporphyrin IX (PpIX)-photobleaching of more than 95% after the delivery of 200 J/cm². This light dose did not induce any side effects. Furthermore, interstitial PDT (iPDT) has been employed within one feasibility trial (n=10) and one Phase I/II trial (n=15). Here, three to six cylindrical light diffusors (20-30 mm length, 200 mW/cm, 720 J/cm) were positioned within the target tissue under stereotactic guidance. Pre-treatment planning was performed with the intent to target the entire tumour volume with a sufficient light dose while also minimising the risk of any light-induced temperature increase. For the feasibility trial patients with small, recurrent gliomas were included, resulting in a median survival of 15 months as well as some unexpected longterm survivals (up to 5 years). The Phase I/II trial employed the same clinical procedures. Here, the 12-month survival was 35% and the median progression-free survival was 6 months. In summary, stereotactic iPDT in combination with treatment-planning could be shown to be a safe and feasible treatment modality. These trials are presently being extended to also include on-line monitoring of PpIX fluorescence and photobleaching kinetics. Preliminary data has revealed dramatically different PpIX levels and photobleaching kinetics. Such data could possibly be employed for realtime treatment monitoring and as an early prognostic marker for the PDT response.

In the PDT practice for tumor patients, the dose and irradiation time for the treatment are chosen by experience and not by real need. To establish advanced PDD-PDT model system for patients, we developed a method for monitoring the cell-death based on a spectrophotometric real-time change in fluorescence in HeLa-tumors during Photofrin®-PDT and ALA-PDT. Here, we describe the results of application of the new PDD-PDT system to human tumors. The fluorescence spectra obtained from human tumors were analyzed by the differential spectral analysis. The mass-spectral changes of tumor tissues during PDD-PDT were also examined by MALDI-TOF-MS/MS. The first author's seborrheic keratosis was monitored with this system during the PDD-PDT with a topically applied ALA-ointment. The changes in fluorescence spectrum were successfully detected, and the tumor regressed completely within 5 months. The differential spectral analysis of PDD-PDT-fluorescence monitoring spectra of tumors and isolated mitochondria showed a marked decrease of three peaks in the red region indicative of the PDD (600 - 720 nm), and a transient rise followed by a decline of peaks in the green region indicative of the PDT (450 - 580 nm). The MALDI-TOF-MS analysis of PDD-PDT HeLa-tumors showed a consumption of Photofrin-deuteroporphyrin and ALA-PpIX, and decreases in protein mass in the range of 4,000 - 16,000 Da, m/z 4929, 8564, 10089, 15000, and an increase in m/z 7002 in a Photofrin® PDD-PDT monitoring tumor.

PDT is clinically useful for precancers (actinic keratoses; AK) of the skin, but the optimal duration for 5-ALA application is still controversial. For basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), cure rates remain inferior to surgical excision. Lack of knowledge about regional levels of PpIX levels within target tissues clearly contribute to these suboptimal results. To investigate PpIX levels achievable in human skin neoplasias in-vivo, a clinical study to monitor PpIX accumulation in vivo was performed. PpIX-fluorescence in patients undergoing ALA-PDT for facial AK was monitored via real-time in-vivo fluorescence dosimetry, with measurements q20 min following application of 5-ALA (Levulan Kerastick). PpIX accumulation followed linear kinetics in nearly all cases. The slopes varied widely, and did not correlate with clinical outcome in all patients. Some patients with a low accumulation of PpIX fluorescence had a good response to therapy, whereas others with high PpIX accumulation required repeat treatment (although not necessarily of the same lesion). PpIX accumulation rates did correlate to a certain degree with the overall amount of erythema. We conclude that unknown factors besides PpIX levels must be critical for the response to treatment. To assess the relationship between PpIX levels in various skin cancers, patients undergoing routine Mohs surgery for BCC or SCC were measured by in-vivo dosimetry at 2 h after 5-ALA application. Overall, a progressive increase in PpIX signal during malignant progression was observed, in the following rank order: Normal skin < AK < SCC ~ BCC.

PDT is an effective method when treating multiple actinic keratoses (field cancerization). The major side effect is pain. Our objectives were to investigate the pain-relieving effect of transcutaneous electrical nerve stimulation (TENS) and peripheral nerve blocks during PDT of field cancerization (FC) of the face and scalp. Patients with field cancerization were included in three studies. In the first study, we examined TENS with an application site on the adjacent dermatome from the PDT area in order to allow the use of water spray during PDT for FC of the scalp and face. In the second study, patients with FC in the facial area received unilateral supraorbital, infraorbital and/or mental nerve blocks. The non-anaesthetised side of the treatment area served as control. In the third study, with similar methodology as in the second study, occipital and supraorbital nerve blocks were combined for FC of the forehead and scalp. The results of the studies strongly support the use of nerve blocks as pain relief during PDT. The use of TENS provided a limited pain reduction, but TENS might be an alternative if the patient disapproves of the use of nerve blocks or is afraid of injections.

This study employed a commercially available, non-invasive, fluorescence imaging system (Dyaderm, Biocam, Germany), to measure protoporphyrin IX (PpIX) concentration at several different stages during clinical dermatological methyl aminolevulinate photodynamic therapy (MAL-PDT). We validated the system prior to use to ensure that the PpIX changes witnessed were accurate and not due to environmental or user induced artifacts. The system was then employed to acquire color (morphological) and fluorescent (physiological) images simultaneously during dermatological PDT. Clinical data was collected from a range of licensed dermatological conditions (actinic keratosis, Bowen's disease and superficial basal cell carcinoma) during initial and subsequent PDT treatment cycles. The initial clinical data indicated that each type of licensed lesion considered responded in a similar manner following the application of Metvix (Galderma, U.K.) and the subsequent light irradiation (Aktilite, Galderma, U.K.). Images acquired three hours after Metvix application showed a significant increase in PpIX concentration within the lesion (P < 0.05), whilst PpIX levels in the surrounding normal tissue remained unaltered. After irradiation, the PpIX concentration was significantly decreased and returned to a level similar to the initial concentration originally observed. Lesions that received subsequent treatment cycles accumulated significantly less PpIX (P < 0.05) prior to irradiation.

Multifocal recurrence of in-situ squamous cell cancer of the oral cavity, pharynx and vocal cord following surgical failure can be a therapeutic dilemma. Salvage surgery or radiation may be an option but morbidity can be significant. We evaluated the potential role of low dose Photofrin (1.2mg/Kg) Photodynamic Therapy for this cohort of patients. A total of 25 patients with multifocal recurrent in-situ squamous cell cancer of the oral cavity, pharynx and vocal cord who had failed local resection, and where additional surgery or radiation therapy would likely result in permanent morbidity, were offered Photodynamic Therapy. PDT consisted of off label infusion of Photofrin (1.2mg/kg) followed 48 hours later by illumination at 630nm employing a light diffuser (300J) and/or microlens (150Jcm²). All patients completed their prescribed PDT and no patient has been lost to follow up (minimum 1 year). No photosensitivity reactions were noted. No significant morbidity was seen. All patients were able to maintain oral nutrition. Procedure related pain was well controlled by one week of oral narcotics. At one month post PDT all patients were biopsy negative in the treatment region and no failures within the treatment region have been noted. No fibrosis or permanent PDT morbidity has been seen with follow up to three years. Vocal cord and voice function were excellent. Three patients developed new regions of in-situ disease outside the PDT fields, two underwent additional PDT and one had laser resection. Low dose Photofrin PDT offers excellent palliation and durable local control of recurrent in-situ squamous cell cancers of the oral cavity, pharynx and true cords. This is a well tolerated therapy. Low dose Photofrin appears to improve selectivity and minimize normal tissue injury. It should be tested in a larger patient population.

Bladder cancer (BC) is among the most expensive oncological diseases. Any improvement in diagnosis or therapy carries a high potential for reducing costs. Fluorescence cystoscopy relies on a selective formation of Protoporphyrin IX (PpIX) or more general photoactive porphyrins (PAP) in malignant urothelium upon instillation of 5-aminolevulinic acid (5-ALA) or its hexyl-derivative h-ALA. Fluorescence cystoscopy equipment has been developed with the aim to compensate for the undesired distortion caused by the tissue optical properties by displaying the red fluorescence simultaneously with the backscattered blue light. Many clinical studies proved a high sensitivity in detecting flat carcinoma in situ and small papillary malignant tumours. As a result, recurrence rates were significantly decreased in most studies. The limitation lies in a low specificity, caused by false positive findings at inflamed bladder wall. Optical coherence tomography (OCT) is currently being investigated as a promising tool to overcome this limitation. H-ALA-PDT (8 or 16 mM h-ALA in 50 ml instillation for 1-2 h, white light source, catheter applicator) has recently been investigated in a phase I study. 17 patients were applied 100 J/cm² (3 patients received incrementing doses of 25 - 50 - 100 J/cm²) during approx. 1 hour irradiation time in 3 sessions, 6 weeks apart. PDT was performed without any technical complications. Complete photobleaching of the PpIX-fluorescence, as intended, could be achieved in 43 of 45 PDT-sessions receiving 100 J/cm². The most prominent side effects were postoperative urgency and bladder pain, all symptoms being more severe after 16 mM h-ALA. Preliminary evaluation shows complete response assessed at 3 months after the third PDT-session (i.e. 6 months after first treatment) in 9 of 12 patients. 2 of these patients were free of recurrence until final follow-up at 84 weeks.

The prevalence of bladder cancer is very high, due to its high recurrence rate in superficial bladder cancer (30 to 85%), which is the staging of approximately 80% of the patients at first diagnosis. Risk of recurrence and progression is associated with grade, stage, presence of concomitant carcinoma in situ, size and number of lesions, as well as time to first recurrence. Recurrences can be partly attributed to new occurrences but also to residual tumors after resection. Incomplete tumor removal has been observed in 30 to 50% of TUR's, especially when dealing with T₁ or poorly visible malignant or pre-malignant disease1. Fluorescence guided resection with 5 amino levulinic acid (ALA) or its hexyl ester derivative (Hexvix, has now unequivocally been demonstrated to increase detection rate and a growing number of studies indicate this has a positive impact on recurrence and progression ratesImplantation of viable tumor cells, dispersed during resection, is a third factor influencing bladder cancer recurrence. The aim of early intravesical therapy is to interfere with cell viability and thus reduce implantation risks.

A novel light source - light blanket composed of a series of parallel cylindrical diffusing fibers (CDF) is designed to substitute the hand-held point source in the PDT treatment of the malignant pleural or intraperitoneal diseases. It achieves more uniform light delivery and less operation time in operating room. The preliminary experiment was performed for a 9cmx9cm light blanket composed of 8 9-cm CDFs. The linear diffusers were placed in parallel fingerlike pockets. The blanket is filled with 0.2 % intralipid scattering medium to improve the uniformity of light distribution. 0.3-mm aluminum foil is used to shield and reflect the light transmission. The full width of the profile of light distribution at half maximum along the perpendicular direction is 7.9cm and 8.1cm with no intralipid and with intralipid. The peak value of the light fluence rate profiles per input power is 11.7mW/cm²/W and 8.6mW/cm²/W respectively. The distribution of light field is scanned using the isotropic detector and the motorized platform. The average fluence rate per input power is 8.6 mW/cm²/W and the standard deviation is 1.6 mW/cm²/W for the scan in air, 7.4 mW/cm²/W and 1.1 mW/cm²/W for the scan with the intralipid layer. The average fluence rate per input power and the standard deviation are 20.0 mW/cm²/W and 2.6 mW/cm²/W respectively in the tissue mimic phantom test. The light blanket design produces a reasonably uniform field for effective light coverage and is flexible to confirm to anatomic structures in intraoperative PDT. It also has great potential value for superficial PDT treatment in clinical application.

Photodynamic therapy (PDT) mediated with verteporfin was investigated as an alternative modality for the treatment of prostate cancer. Materials and Methods: Vertoporfin-mediated photodynamic effects on the prostate and its adjacent structures (underlying colon and bladder) were evaluated in a healthy canine model. Interstitial prostate PDT was performed by irradiating individual lobes with a diode laser (689 nm) and 1-cm cylindrical diffuser fibers at various light doses and drug-light intervals (DLI) to activate the IV administrated photosensitizer (0.5 or 2 mg/kg). The sensitivity of the adjacent tissues to Vertoporfin-PDT was determined by superficially irradiating the serosal surface of the bladder and colon with a microlens fiber. The prostate and adjacent tissues were harvested one-week after the treatment and subjected to histopathological examination. Results: Histopathological examinations confirmed that verteporfin PDT could destroy a clinically significant volume of prostatic tissue in the animal model. At the drug dose of 0.5 mg/kg, the light irradiation of 100 J/cm could induce a lesion diameter of 2 cm at DLI of 15 min and 1.2 cm at DLI of 3 hrs, respectively. This implies a strong influence of DLI on the lesion volume. The shorter DLI might produce stronger vascular effect and therefore more severe tissue damage. The colon was more sensitive to verteporfin PDT than the bladder. At the possible light dose level caused by light scattering during intra-prostate irradiation, the damage to the bladder and colon were superficial and minimal. Conclusions: The preliminary results clearly demonstrate that verteporfin PDT could be an effective means to destroy prostate gland and its usefulness for the treatment of prostate cancer is worth further investigation.

Objectives: To evaluate the effectiveness of topical 5-aminolevulinic acid (ALA)- medicated photodynamic therapy (ALA PDT) for the treatment of moderate to severe acne vulgaris. Methods: Sixteen Chinese patients with moderate to severe facial acne were treated with 1-3 courses of ALA PDT. ALA cream (3%) was freshly prepared and applied to acne lesions for 3-4 h. The lesions were irradiated by a 635 nm diode laser at dose levels of 60 - 80 J/cm² at 100 mW/cm². Clinical assessments were conducted before and after treatment up to 3 months. Results: All patents showed response to ALA PDT. Complete clearance was seen in 10 patients (62.5%) and partial clearance in 6 patients (37.5%). One case showed recurrence after complete clearance at 2 months and another two showed recurrence after complete clearance at 3 months. However, the number of new lesions were significantly reduced. Adverse effects were minimal. Conclusions: The results of this preliminary clinical study is encouraging. ALA PDT is a simple, safe and useful therapeutic option for the treatment of moderate to severe acne. Further studies to evaluate the treatment with a larger number of patients and for a longer period of follow-up are needed.

Topical protoporphyrin IX (PPIX) induced photodynamic therapy (PDT) of basal cell carcinoma (BCC) produces good clinical outcomes with excellent cosmesis as long as the disease remains superficial. Efficacy for nodular BCC however appears inferior to standard treatment unless repeat treatments are performed. Enhancement is therefore required and is possible by employing iron chelating agents to temporarily increase PPIX accumulation above the levels normally obtained using aminolevulinic acid (ALA) or the methyl ester of ALA (MAL) alone. In vitro studies investigated the effect of the novel iron chelator, CP94 on necrotic or apoptotic cell death in cultured human skin fibroblasts and epidermal carcinoma cells incubated with MAL. Furthermore, following a dose escalating safety study conducted with ALA in patients, an additional twelve nodular BCCs were recruited for topical treatment with standard MAL-PDT +/- increasing doses of CP94. Six weeks later following clinical assessment, the whole treatment site was excised for histological analysis. CP94 produced greater cell death in vitro when administered in conjunction with MAL than this porphyrin precursor could produce when administered alone. Clinically, PDT treatment using Metvix + CP94 was a simple and safe modification associated with a trend of reduced tumor thickness with increasing CP94 dose.

Photodynamic therapy of tumors involving Type 2 photosenstizers has been conspicuously successful, but the Type 1 process, in contrast, has not received much attention despite its considerable potential. Accordingly, several classes of molecules containing fragile bonds such as azido (-N=N=N), azo (-N=N-), sulfenato (-S-O-) and oxaza (-N-O-) functional groups that produce reactive intermediates such as radicals and nitrenes upon photoexcitation were prepared and tested for cell viability using U397 leukemia cell line. The azido photosensitizer was conjugated to leukemia cell binding peptide, SFFWRLS, for targeted cell viability study. The cells were incubated with the photosensitizer at various concentrations, and were illuminated for 5, 10, and 20 minutes. The results show that all the photosensitizers caused cell death compared to the controls when exposed to both the photosensitizers and light. Most importantly, selective cell death was observed with the azido peptide conjugate 6, which clearly demonstrates that these Type 1 sensitizers are useful for phototherapeutic applications.

Various tetrapyrroles act as photosensitizers by efficiently generating singlet oxygen. Hydrophobic or amphiphilic photosensitizers are taken up by cells and are usually located in various cellular lipid membranes. Passive uptake by a membrane depends on biophysical properties of the membrane, such as its composition, temperature, phase, fluidity, electric potential etc., as well as on the external solution's properties. Although the intrinsic lifetime of singlet oxygen in the membrane phase is 10-30 μs, depending on lipid composition, it escapes much faster out of the membrane into the external or internal aqueous medium, where its lifetime is <3 μs. Any damage that singlet oxygen might inflict to membrane constituents, i.e. proteins or lipids, must thus occur while it is diffusing in the membrane. As a result, photosensitization efficiency depends, among others, on the location of the sensitizer in the membrane. Singlet oxygen can cause oxidative damage to two classes of targets in the membrane: lipids and proteins. Depolarization of the Nernst electric potential on cells' membranes was observed, but it is not clear whether lipid oxidation is a relevant factor leading to abolishing the resting potential of cells' membranes and to their death. We present a study of the effect of membrane lipid composition and the dissipation of the electric potential that is generated across the membrane. We find a clear correlation between the structure and unsaturation of lipids and the leakage of the membrane, which can be caused by their photosensitized oxidization. We demonstrate here that when liposomes are composed of mixtures similar to natural membranes, and photosensitization is being carried out under usual PDT conditions, photodamage to the lipids is not likely to cause enhanced permeability of ions through the membrane, which could be a mechanism that leads to cell death.

The scanning fiber endoscope (SFE), an ultrathin laser scanning endoscope capable of producing 500-line color images at 30-Hz frame rate, has been developed at the University of Washington. The SFE probe is a 1-mm diameter by 9-mm long rigid scanner at the tip of a highly flexible and robust tether (minimum bend radius < 8- mm), comprised of helically wound optical fibers and electrical wires within a protective sheath. The unique physical characteristics of this system have allowed the camera to navigate narrow passages where other technologies have suffered from reduced image quality and fragility, such as imaging the peripheral airways and bile duct. The scanning engine of the SFE allows for laser-based imaging and potential applications of pixel-accurate therapy in remote regions of the body. In this study, the standard SFE operation has been tailored to create widefield fluorescence images for photodynamic detection. A kidney with renal cell carcinoma was excised from an Eker rat after post-mortem in situ perfusion with 0.4 mM hypericin. The 442-nm blue and 532-nm green laser illumination sources were used for both standard reflectance imaging and fluorescence excitation, while the red 635- nm illumination was disabled. Red detection signal gain was increased to amplify the red fluorescence signal from the photomultiplier tube and within the computer image display. Results show green and blue reflectance images overlaid with red fluorescence signal in tumor regions of the kidney. These imaging capabilities portend future adoption of laser-based SFE imaging for real-time PDD.

Photodynamic therapy (PDT) as a treatment modality for infectious disease has shown promise. However, most of the antimicrobial photosensitizers (PS) non-preferentially accumulate in both bacteria and host tissues, causing host tissue phototoxicity during treatment. We have developed a new antimicrobial PDT strategy which exploits beta-lactam resistance mechanism, one of the major drug-resistance bacteria evolved, to achieve enhanced target specificity with limited host damage. Our strategy comprises a prodrug construct with a PS and a quencher linked by beta-lactam ring, resulting in a diminished phototoxicity. This construct, beta-lactamase enzyme-activated-photosensitizer (beta-LEAP), can only be activated in the presence of both light and bacteria, and remains inactive elsewhere such as mammalian tissue. Beta-LEAP construct had shown specific cleavage by purified beta-lactamase and by beta-lactamase over-expressing methicillin resistant Staphylococcus aureus (MRSA). Specific photodynamic toxicity was observed towards MRSA, while dark and light toxicity were equivalent to reference strains. The prodrug design, synthesis and photophysical properties will be discussed.

Porphyrins bearing sugars and other motifs are proposed for a variety of therapeutic applications. Non-hydrolysable glyco conjugates of porphyrins can be formed in rapid, room temperature reacting in greater than 90% yields from tetraperfluorophenyporphyrin. Additional functional groups can be appended using the same chemistry but different stoichiometries of the reagents. Thus sugars, amines, peptides, and cationic moieties designed to target cancer cells or other diseased or disease-causing cells are made rapidly and cleanly. These compounds can then be rapidly screened for cell uptake, or selected from combinatorial libraries by cell uptake assays using a combination of fluorescence microscopy and mass spectrometry. Modifications of the macrocycle allow fine-tuning of the photonic properties for specific medical, imaging, or biochemical applications.

In order to evaluate cytotoxic effects of secondary Auger electron emission(Photon Activation Therapy:PAT) from alginate-coated iron nanoparticles(Alg-SNP), Alg-SNP-uptaken C6 glioma cell lines were irradiated with 6.89/7.2 Kev synchrotron X-ray. 0-125 Gy were irradiated on three experimental groups including No-SNP group incubating without SNP as control group, 6hr-SNP group incubating with SNP for 6hr and ON-SNP group incubating with SNP overnight. Irradiated cells were stained with Acridine Orange(AO) and Edithium Bromide(EB) to count their viability with fluorescent microscopy in comparison with control groups. AO stained in damaged DNA, giving FL color change in X-ray plus SNP group. EB did not or less enter inside the cell nucleus of control group. In contrast, EB entered inside the cell nucleus of Alg-SNP group which means more damage compared with Control groups. The results of MTT assay demonstrated a X-ray dose-dependent reduction generally in cell viability in the experimental groups. 3 or 9 times increase in cell survival loss rate was observed at 6hr-SNP and ON-SNP groups, respectively compared to No-SNP control group in first experiment that was done to test cell survival rate at relatively lower dose, from 0 to 50 Gy. In second experiment X-ray dose was increased to 125 Gy. Survival loss was sharply decreased in a relatively lower dose from 5 to 25 Gy, and then demonstrated an exponentially decreasing behavior with a convergence until 125 Gy for each group. This observation suggests PAT effects on the cell directly by X-ray in the presence of Alg-SNP occurs within lower X-ray dose, and conventional X-ray radiation effect becomes dominant in higher X-ray dose. The cell viability loss of ON-SNP group was three times higher compared with that of 6hr-SNP group. In conclusion, it is possible to design photodynamic X-ray therapy study using a monochromatic x-ray energy and metal nanoparticle as x-ray sensitizer, which may enable new X-ray PDT to disseminated tumors without side effects to normal surrounding tissue.

5-aminolevulinic acid-mediated photodynamic therapy (ALA-PDT) is the most widely practiced form of PDT in dermatology. One of the advantages of ALA-PDT is that undesirable photosensitization lasts only for 24-48 h. In order to optimize ALA-PDT it is necessary to understand the mechanisms controlling intracellular PpIX clearance (efflux and transformation into heme) in order to decrease protoporphyrin IX (PpIX) clearance rates in the early stages of its production. The aim of this study was to investigate the factors controlling the clearance of intracellular PpIX. Fluorescence spectroscopy was used to study PpIX kinetics in WiDr cells initially treated with ALA. The clearance rate of PpIX in WiDr cells was faster after application of a low concentration of ALA (0.1 mM) than after application of high concentration of ALA (1 mM). PpIX was cleared faster from cells which initially were seeded at low densities than cells seeded at higher densities. The presence of the iron chelator deferoxamine reduced the clearance rate of PpIX, while the presence of ferrous sulfate acted oppositely. The decay rate of PpIX in WiDr cells was faster at higher temperature than at lower. The ferrochelatase activity at pH 7.2 was significantly greater than that at pH 6.7. ALA concentration, application time, cell density, temperature, pH, intracellular iron content, intracellular amount and localization of PpIX are factors controlling PpIX clearance.

Photodynamic therapy (PDT) has been successfully used to treat many malignancies, and has afforded highly encouraging results in skin cancers such as basal cell carcinoma. However, pigmented melanoma remains a notable exception from the range of tumors treated by PDT largely due to the fact that melanin has high absorption of light in wavelength regions where most clinically approved photosensitizers (PS) absorb light (600-690 nm). Moreover, melanoma cells sequester exogenous molecules including photosensitizers inside melanosomes. The aforementioned drawbacks of the clinically used PS have motivated us to search for new classes of PS with improved spectral properties, such as bacteriochlorins (BC) to be used in PDT of melanoma. To overcome the PDT-resistance mechanisms of melanoma, particularly the high optical absorption of melanin, three near-infrared (NIR) absorbing synthetic stable BC were used in PDT treatment of melanoma. Dose and fluence dependent cell killing, intracellular localization (particularly in melanosomes), and correlation between the melanin level and cell death were examined. Intracellular melanosomes are ruptured after illumination as shown by electron microscopy. The best in vitro performing BC were tested upon delivery in micellar nanoparticles against a mouse pigmented melanoma. Two of the BC were effective at significantly lower concentrations (<0.5 μM) than common photosensitizers in present use.

Selenium, an essential trace element possessing anti-carcinogenic properties, can induce apoptosis in cancer cells. Our goal was to investigate the enhanced anti-tumor effects of photodynamic therapy (PDT) plus selenium in TC-1 tumor cells implanted into mice. The MTT assay and tumor growth inhibition study were evaluated at various time intervals after the PDT plus a various dose of selenium. Following Radachlorin injections after 3 hr, the mice were then administrated selenium (2ug/kg b.w.) and then, tumors were treated with external light treatment (300 J/cm²). The selenium was administered daily for 20 days. PDT or selenium was found to be more compared to control groups. Moreover, the PDT combined with selenium demonstrated a significant suppression of tumor growth in vitro and in vivo. The tumor growth by the PDT combined with selenium was significantly reduced. These data suggest that selenium plus PDT can induce a significant tumor suppression response compared with PDT alone. Also, it can be an effective approach to induce anti-cancer therapy strategy.

Port wine stain (PWS) birthmarks are a congenital cutaneous vascular malformation involving ecstatic post-capillary venules. Current standard treatment for PWS is the pulsed dye laser (PDL). Vascular-targeted photodynamic therapy (PDT) has been used for the treatment of PWS in China since the early 1990's. Both can achieve a certain degree of color blanching in various types of PWS lesions. However, the majority of PWS lesions require multiple treatments. Some PWS lesions can recur or become darker after successful treatment. Recently, it has been proposed that this phenomenon might be initiated by neoangiogenesis that can be caused by treatment via wound healing response. The combined use of photothermolysis and a topical application of an angiogenic inhibitor such as Imiquimod and Rapamycin, were evaluated in several pilot studies. It is well-known that PDT can induce various host immune responses VEGF overexpression. Recent clinical data also show that improved clinical outcomes are obtained through the combination of ocular PDT and anti-VEGF therapy. This article will discuss rationales and implications of using such a combination modality and highlight recent progress based on our clinical experience and published data.

It has been speculated that topical application of 5-aminolevulinic acid (ALA) or methyl 5-aminolevulinate (MAL) may be more painful during light exposure after longer application times of the compounds than after shorter times, even though the same levels of protoporphyrin IX (PpIX) is produced in both cases. The aim of our study was to investigate pain induction in the build-up and clearance phases of PpIX in the skin of healthy volunteers. 0.6 mmol/g of ALA (10% wt/wt) and MAL (11% wt/wt) creams were applied on the volunteers. The creams were maintained on the spots for 20- 24 hours and then wiped off. Subsequently, fresh creams were applied on the other arm of the volunteers for 4- 6 hours. Fluorescence emission spectra for all spots were measured every hour until the fluorescence levels were similar in both arms for ALA and MAL. Then the test areas were exposed to light until pain occurred. Time for pain to occur was recorded. The fluorescence of PpIX was measured before and after light exposure. PDT in the clearance phase seems to induce pain faster than in the build-up phase for ALA and MAL. Due to large interpersonal variations between volunteers further investigation is needed.

We reviewed the outcome of combined photodynamic therapy (PDT) and high dose rate brachytherapy (HDR) for patients with symptomatic obstruction from endobronchial non-small cell lung cancer. Methods: Nine patients who received combined PDT and HDR for endobronchial cancers were identified and their charts reviewed. The patients were eight males and one female aged 52-73 at diagnosis, initially presenting with various stages of disease: stage IA (N=1), stage IIA (N=1), stage III (N=6), and stage IV (N=1). Intervention was with HDR (500 cGy to 5 mm once weekly for 3 weeks) and PDT (2 mg/kg Photofrin, followed by 200 J/cm² illumination 48 hours post infusion). Treatment group 1 (TG-1, N=7) received HDR first; Treatment group 2 (TG-2, N=2) received PDT first. Patients were followed by regular bronchoscopies. Results: Treatments were well tolerated, all patients completed therapy, and none were lost to follow-up. In TG-1, local tumor control was achieved in six of seven patients for: 3 months (until death), 15 months, 2+ years (until death), 2+ years (ongoing), and 5+ years (ongoing, N=2). In TG-2, local control was achieved in only one patient, for 84 days. Morbidities included: stenosis and/or other reversible benign local tissue reactions (N=8); photosensitivity reaction (N=2), and self-limited pleural effusion (N=2). Conclusions: Combined HDR/PDT treatment for endobronchial tumors is well tolerated and can achieve prolonged local control with acceptable morbidity when PDT follows HDR and when the spacing between treatments is one month or less. This treatment regimen should be studied in a larger patient population.

Cervical intraepithelial neoplasia (CIN) is the precursor of invasive cervical cancer. Previous studies indicated that photodynamic therapy (PDT) represents an effective treatment modality in CIN. In 28 patients with CIN 1 - 3, 1 - 2 cycles of PDT were conducted using hexaminolevulinate (HAL) or methylaminolevulinate (MAL) and a special light delivery system. After 6 months, biopsies were obtained to assess response. The overall response rate for complete or partial response was 65%. Photodynamic therapy using new ALA esters is effective and may offer unique advantages in the therapy of CIN.

Tumor vasculature is an attractive target for cancer therapy due to its accessibility to blood-borne therapeutic agents and the dependence of tumor cells on a functional blood supply for survival and growth. Vascular targeting photodynamic therapy (vPDT) is a novel modality based on the selective laser light activation of photosensitizers localized inside tumor vasculature to shutdown tumor vascular function. Although this vascular targeting therapy is showing great promise for cancer treatment, tumor recurrence has been observed in both preclinical and clinical studies. In this study, we intend to enhance the therapeutic outcome of vascular targeting PDT by combining it with combretastatin A4 phosphate (CA4P), a blood flow inhibitor. We found that the combination of CA4P and vPDT significantly increased endothelial cell apoptosis than each single therapy. Western blot analysis suggests that myosin light chain kinase (MLCK) is a common target of CA4P and vPDT. In a PC-3 prostate tumor model, we found that CA4P was able to greatly enhance tumor response to vPDT. These results demonstrate that CA4P and vPDT can be combined to enhance the therapeutic effect.

Hexaminolevulinate fluorescence cystoscopy by the addition of a specific tissue fluorophore enhances the contrast between benign and malignant epithelial (urothelial) cells in the bladder. Improved detection of flat and papillary tumors as confirmed in recent phase III clinical trials allows the urologist to obtain a precise information on the disease extent at the whole surface of the bladder wall. With gaining experience, management of non muscle invasive bladder cancer improves in readiness and accuracy.

Multi-drug resistant Acinetobacter baumanii infections represent a growing problem, especially in traumatic wounds and burns suffered by military personnel injured in Middle Eastern conflicts. Effective treatment using traditional antibiotics can be extremely difficult and new antimicrobial approaches are being investigated. One of these antimicrobial alternatives could be the combination of non-toxic photosensitizers (PS) and visible light known as photodynamic therapy (PDT). We report on the establishment of a new mouse model of full thickness thermal burns infected with a bioluminescent derivative of a clinical Iraqi isolate of A. baumannii and its PDT treatment by topical application of a PS produced by covalent conjugation chlorin(e6) to polyethylenimine followed by illumination of the burn surface with red light. Application of 10⁸ A. baumannii cells to the surface of 10-second burns made on the dorsal surface of shaved female BALB/c mice led to chronic infections that lasted on average 22 days characterized by a remarkably stable bacterial bioluminescence. PDT carried out on day 0 soon after applying bacteria gave over three logs of loss of bacterial luminescence in a light exposure dependent manner, while PDT carried out on day 1 and day 2 gave approximately a 1.7-log reduction. Application of PS dissolved in 10% or 20% DMSO without light gave only modest reduction in bacterial luminescence from mouse burns. Some bacterial regrowth in the treated burn was observed but was generally modest. It was also found that PDT did not lead to inhibition of wound healing. The data suggest that PDT may be an effective new treatment for multi-drug resistant localized A. baumannii infections.

The main cause of morbidity and mortality in cystic fibrosis (CF) sufferers is progressive pulmonary damage caused by recurrent and often unremitting respiratory tract infection. Causative organisms include Pseudomonas aeruginosa and Haemophilus influenzae, but in recent years the Burkholderia cepacia complex has come to the fore. This group of highly drug-resistant Gram-negative bacteria are associated with a rapid decline in lung function and the often fatal cepacia syndrome, with treatment limited to patient segregation and marginally effective antibacterial regimens. Thus, development of an effective treatment is of the upmost importance. PACT, a non-target specific therapy, has proven successful in killing both Gram-positive and Gram-negative bacteria. In this study, planktonic cultures of six strains of the B. cepacia complex were irradiated (635 nm, 200 J cm^-2,10 minutes irradiation) following 30 seconds incubation with methylene blue (MB) or meso-tetra (N-methyl-4-pyridyl) porphine tetra tosylate (TMP). Rates of kill of > 99 % were achieved with MB- and TMP-PACT. A MB concentration of 50 μg ml^-1 and TMP concentration of 500 μg ml^-1 were associated with highest percentage kills for each photosensitizer. PACT is an attractive option for treatment of B.cepacia complex infection. Further study, involving biofilm culture susceptibility, delivery of light to the target and in vivo testing will be necessary before it PACT becomes a viable treatment option for CF patients who are colonised or infected with B. cepacia complex.

The nosocomial infection rate has increased dramatically due to emergence of antibiotic resistant bacterial strains such as methicillin resistant Staphylococcus aureus (MRSA). The primary anatomical site of MRSA colonization is the anterior nares, and this reservoir represents a primary vector of transmission from non-infected carriers to susceptible individuals. Antimicrobial photodynamic therapy (aPDT) has been used successfully for topical disinfection in the oral cavity. The aim of this study was to evaluate the utility of aPDT for nasal MRSA decolonization at the preclinical and clinical level. The nasal aPDT system consists of a 670 nm diode laser fibre-optically coupled to a disposable light diffusing tip, used to activate a methylene blue based photosensitizer formulation. Preclinical testing was done both in a custom nasal reservoir model and on human skin cultures colonized on the epithelial surface with MRSA. Human clinical testing was performed by clinicians in regions in which the system is approved by the regulatory authority. In vitro testing demonstrated that aPDT eradicated planktonic MRSA in an energy and photosensitizer concentration dependent manner. Furthermore, aPDT eliminated sustained colonization of MRSA on cultured human epithelial surfaces, an effect that was sustained over multiple days post-treatment. In preliminary human testing, aPDT eradicated MRSA completely from the nose with total treatment times <10 minutes. aPDT is effective against MRSA when used topically in the nose. Energy dose and photosensitizer parameters have been optimized for the nasal environment. Controlled clinical studies are currently underway to further evaluate safety and efficacy.

Photodynamic therapy has emerged as a possible supplement to the existing protocols for endodontic disinfection. Microbes are known to gain significant ecological advantage when they survive as coaggregates and biofilms in an infected tissue. Such microbial coaggregates and biofilms have been confirmed to play a key role in the pathogenicity of many infections. So far, not many studies have correlated the efficacy of antimicrobial photodynamic inactivation (APDI) to the different modes of bacterial growth. This study aims to evaluate the APDI of 3 strains of Enterococcus faecalis in planktonic phase, in a co-aggregated suspension and in a 4-day old biofilm. The results showed that the biofilm mode of growth offered the greatest resistance to APDI and the inclusion of an efflux pump inhibitor significantly increased the APDI of biofilm bacteria. From this study, we conclude that APDI of bacteria in biofilms is the most challenging and that the use of bacterial efflux pump inhibitors enhances its photodynamic antibiofilm efficacy.

Photodynamic therapy has been demonstrated to effectively kill human periopathogens in vitro. However, the translation of in vitro work to in vivo clinical efficacy has been difficult due to the number of variables present in any given patient. Parameters such as photosensitizer concentration, duration of light therapy and amount of light delivered to the target tissue all play a role in the dose response of PDT in vivo. In this 121 patient study we kept all parameters the same except for light dose which was delivered at either 150 mW or 220 mW. This clearly demonstrated the clinical benefits of a higher light dose in the treatment of periodontitis.

Burns are frequently contamined by pathogenic microorganisms and the widespread occurrence of antibiotic resistant strains of Pseudomonas aeruginosa in hospitals is a matter of growing concern. Hypocrellin B (HB) is a new generation photosensitizer extracted from the fungus Hypocrella bambusae with absorption bands at 460, 546 and 584 nm. Lanthanide ions change the HB molecular structure and a red shift in the absorption band is observed as well as an increase in the singlet oxygen quantum yield. In this study, we report the use of HB:La⁺³ to kill resistant strain of P. aeruginosa infected burns. Burns were produced on the back of mice and wounds were infected subcutaneously with 1x10⁹ cfu/mL of P. aeruginosa. Three-hours after inoculation, the animals were divided into 4 groups: control, HB:La⁺³, blue LED and HB:La⁺³+blue LED. PDT was performed using 10μM HB:La+3 and 500mW light-emitting diode (LED) emitting at λ=470nm±20nm during 120s. The animals of all groups were killed and the infected skin was removed for bacterial counting. Mice with photosensitizer alone, light alone or untreated infected wounds presented 1x10⁸ cfu/g while mice PDT-treated showed a reduction of 2 logs compared to untreated control. These results suggest that HB:La⁺³ associated to blue LED is effective in diminishing antibiotic resistant strain P. aeruginosa in infected burns.

The destruction of infectious pathogens by photodynamic therapy (PDT) is an emerging modality. We demonstrated the efficacy of PDT for the management of cutaneous leishmaniasis in our previous studies. However, much remains to be done for the improvement of PDT regimens. The modulation of the immune response by photochemistry is an exciting but under-explored area of PDT research. The goal of this study is to understand the mechanisms of the augmentation of the host immune response after PDT of cutaneous leishmaniasis (CL). We found that PDT with phenoxiazine analogues was capable for induction of Th1 immune response due to stimulation of IL- 12 production by dendritic cells. Single PDT treatment facilitated fast healing of the CL lesions due to effective parasite eradication and augmentation of the immune system. Comparative study with different photosensitizers (PS) (porphyrins, pehnoxiazines) demonstrated different immunomodulating properties of PDT depending on chemical class of PS. Knowing the particular profiles and immunomodulating properties of the pertinent PSs allows us to select the optimal PS with regards to both the photodestructive and immunostimulating potential.

The prevalence of antibiotic resistant bacteria necessitates exploration of alternative approaches to treat hospital and community acquired infections. The aim of this study was to determine whether bacterial pathogens develop resistance to antimicrobial photodynamic therapy (aPDT) during repeated sub-lethal challenge. Antibiotic sensitive and resistant strains of S. aureus and antibiotic sensitive E. coli were subjected to repeat PDT treatments using a methylene blue photosensitizer formulation and 670 nm illumination from a non-thermal diode laser. Parameters were adjusted such that kills were <100% so that surviving colonies could be passaged for subsequent exposures. With each repeat, kills were compared to those using non-exposed cultures of the same strain. Oxacillin resistance was induced in S. aureus using a disc diffusion method. For each experiment, "virgin" and "repeat" cultures were exposed to methylene blue at 0.01% w/v and illuminated with an energy dose of 20.6 J/cm². No significant difference in killing of E. coli (repeat vs. virgin culture) was observed through 11 repeat exposures. Similar results were seen using MSSA and MRSA, wherein kill rate did not significantly differ from control over 25 repeat exposures. In contrast, complete oxacillin resistance could be generated in S. aureus over a limited number of exposures. PDT is effective in the eradication of pathogens including antibiotic resistance strains. Furthermore, repeated sub-lethal exposure does not induce resistance to subsequent PDT treatments. The absence of resistance formation represents a significant advantage of PDT over traditional antibiotics.

Photodynamic inactivation (PDI) of microorganisms is successfully applied against Gram (+) microorganisms. However the majority of photosensitizers poorly affect on Gram (-) microorganisms. At present number of works have shown that cationic photosensitizers are able to induce photoinactivation both Gram (+) and Gram (-) microorganisms. The purpose of this work was definition of more effective new cationic pyridylporphyrins with various coordinated metals and functional groups for destruction of Gram (-) microorganisms. The efficiency of new cationic porphyrins and metalloporphyrins (9 compounds) was tested against Gram (-) microorganism E. coli (strain Κ-12). The testing results show high efficiency of metalloporphyrins, especially silver complexes, against E. coli microorganism under dark conditions. 50 % and 100 % cell growth inhibitory concentrations (IC₅₀ and IC₁₀₀ values, accordingly) of studied metallocomplexes are considerably lower in comparison with metal-free porphyrins. At the same time the Zncomplexes of porphyrins are more phototoxic than their metal-free analogues. Zn-metalloporphyrins with allyl and butyl functional groups were shown the highest efficiency against E. coli. The photodynamic action of cationic Zn -TBut4PyP metalloporphyrin against Gram(+) (St. aureus and St. epidermis) and Gram(-) (E.coli, strain K-12 and Salmonella sp.) microorganisms was investigated. It is revealed, that Gram (+) microorganisms were 3-5 times more susceptible to the compounds' phototoxic influence than Gram (-) microorganisms.

The photophysics and mechanisms of cell killing by photodynamic therapy (PDT) have been extensively studied in recent years, and PDT has received regulatory approval for the treatment of a number of diseases worldwide. As the application of this treatment modality expands with regard to both anatomical sites and diseases, it is important to develop strategies for enhancing PDT outcomes. Our group has focused on developing targeting strategies to enhance PDT for both cancerous as well as anti-microbial applications. In this article, we will discuss photosensitizer modification and conjugation strategies for targeted antimicrobial photodynamic therapy.

Over the last several decades little progress has been made in the therapy and treatment monitoring of pancreas adenocarcinoma, a devastating and aggressive form of cancer that has a 5-year patient survival rate of 3%. Currently, investigations for the use of interstitial Verteporfin photodynamic therapy (PDT) are being undertaken in both orthotopic xenograft mouse models and in human clinical trials. In the mouse models, magnetic resonance (MR) imaging has been used as a measure of surrogate response to Verteporfin PDT; however, MR imaging alone lacks the molecular information required to assess the metabolic function and growth rates of the tumor immediately after treatment. We propose the implementation of MR-guided fluorescence tomography in conjunction with a fluorescently labeled (IR-Dye 800 CW, LI-COR) epidermal growth factor (EGF) as a molecular measure of surrogate response. To demonstrate the effectiveness of MR-guided diffuse fluorescence tomography for molecular imaging, we have used the AsPC-1 (+EGFR) human pancreatic adenocarcinoma in an orthotopic mouse model. EGF IRDye 800CW was injected 48 hours prior to imaging. MR image sequences were collected simultaneously with the fluorescence data using a MR-coupled diffuse optical tomography system. Image reconstruction was performed multiple times with varying abdominal organ segmentation in order to obtain a optimal tomographic image. It is shown that diffuse fluorescence tomography of the orthotopic pancreas model is feasible, with consideration of confounding fluorescence signals from the multiple organs and tissues surrounding the pancreas. MR-guided diffuse fluorescence tomography will be used to monitor EGF response after photodynamic therapy. Additionally, it provide the opportunity to individualize subsequent therapies based on response to PDT as well as to evaluate the success of combination therapies, such as PDT with chemotherapy, antibody therapy or even radiation.

Background: Endoscopic mucosal resection (EMR) was originated to treat early gastric cancer (EGC). EMR was suitable for small, mucosal and well-differentiated adenocarcinoma without ulceration. It was difficult to resect larger tumors en bloc by this method. In recent years, a more useful method, endoscopic submuscosal dissection (ESD) has been developed, which enables en bloc resection of large mucosal lesions. On the contrary, photodynamic therapy (PDT) is applicable to submucosal, poorly differentiated, or carcinoma with ulceration. In the era of ESD, we evaluated the value of Photofrin-PDT. Patients & Methods: We applied PDT to 36 patients including three advanced cancers, who had been excluded from EMR (ESD) and were at high risks for surgery or refused surgery. Four EGC patients who had not been cured by EMR (ESD) were included. Our PDT procedure consisted of polyhematoporphyrin ether/ester administration (Photofrin, 2 mg/Kg) and pulsed excimer dye laser irradiation at 630 nm 48 hours (and 96 hours) after sensitization. Results: Complete response (CR) at three months was obtained in 84% (21/25) of mucosal cancer and in 50% (4/8) of submucosal cancer. Although three patients with an advanced cancer improved but were not cured, quality of their life was maintained. There were no serious side effects except skin photosensitivity. Conclusion: Photofrin-PDT should be applied not only EGC patients who are excluded from ESD and have not been cured by ESD with poor risk for surgery, and have high possibilitiy to be cured by PDT, but also advanced cancer patients for local improvement of lesions.

Introduction: The rate of PpIX fluorescence photobleaching is routinely used as a dose metric for ALA-PDT. Diffuse reflection spectroscopy is often used to account for variations in tissue optical properties at the photosensitizer excitation and emission bands. It can be used to quantify changes in vascular parameters, such as blood volume fraction and saturation, and can aid understanding of tissue response to PDT. The volume and(/or) depth over which these signals are acquired are critical. The aim of this study is to use quantitative reflectance spectroscopy (DPS) to correct fluorescence for changes in tissue optical properties and monitor PDT. Materials & Methods: ALA was topically applied to hairless mice skin and the incubated spot was treated with PDT according to fractionated illumination schemes. DPS measurements of vascular parameters and optical properties were performed directly before and after illumination. Both the differential signal, delivery-and-collection-fiber signal and the collection fiber signal, which all probe different measurement volumes, are analyzed. Results & Conclusions: Analysis of DPS measurements shows that at the depth where most fluorescence originates, there is almost no blood present. During PDT vascular parameters at this depth stay constant. In more oxygenated layers of the tissue, the optical properties do change during PDT, suggesting that only a small part of PpIX fluorescence originates from the interesting depths where vascular response occurs. Correcting fluorescence emission spectra for optical changes at specific depths and not for the total of changes in a larger volume, as is usually done now, can improve PpIX photobleaching based treatment monitoring.

Tissue heterogeneities as well as distinct metabolic status and cellular types within a tumor may results in a nonhomogenous necrosis. The possibility of PDT surviving cells within a treated volume has relevant clinical significance. The major aim of this study was to analyze, on normal rat liver, the cell viability and surviving after PDT. The porphyrin was injected through the cava vein at concentration of 1.5 mg/Kg. The induced necrosis was qualitatively investigated varying the used drug light interval (30 min, 1, 3, 6, 24 and 36 h) and total delivered dose (20, 50, 100, 150 and 200 J/cm²). A diode laser at 630 nm and irradiance of 150 mW/cm² was employed. The exposed livers were removed after the animals were killed by anesthesia overdose, 30 h after illumination. Slides were processed by HE analysis for the determination of the overall aspects of the necrotic and non-treated liver. We observed necrosis of central vein and presence of surviving cell around the portal triad within the necrotic volume, suggesting PDT-resistant regions of the tissue. Possible hypothesis for the observation may be: the absence of photosensitizer; insufficient light dose (below threshold); and distinct metabolic status in the portal triad microregions decreases oxygen availability to photodynamic reaction. The cells surrounding portal triad presented a higher resistance even when 200 J/cm² was applied. In contrast, the cells closer to the central vein after 20 J/cm² were already susceptible to the action of PDT. Different aspects of the problem are presented.

The chicken embryo's chorioallantoic membrane (CAM) is widely used as an in vivo model to study the vascular effects induced by agents administrated topically or intravenously. Hence, in the vascular plexus of this respiratory membrane, angiogenic and anti-angiogenic agents, as well as phototoxic effects have been studied. The main goal of this study was to characterize the capillary network of the CAM after topical administration of dimethyl sulfoxid (DMSO), a frequently used solvent of lipophylic drugs, including potent anti-VEGF agents. The CAM capillaries were observed between days 8 and 9 of the embryo development, with an epi-fluorescence microscope equipped with a sensitive camera by intravenous injection of a fluorescent agent and a non-fluorescing absorber (in the extra-embryonic cavity) to screen the tissue background fluorescence. The fluorescence images of the CAM vasculature were then processed in order to obtain a skeleton of the vessels and capillaries. This was done to quantify descriptors such as the number of branching points/mm², the mean area value of the vessels network meshes, and the mean of the 3^rd quartile of the histogram of these meshes, were then extracted. Our results demonstrate that the topical administration of an aqueous solution of 20 μl of DMSO at concentrations equal or larger than 0.1% turned out to modify the capillary network morphology in a dose-dependent manner as compared to the control (20 μl of 0.9% NaCl).

The mechanisms of Photodynamic therapy (PDT) include singlet oxygen and reactive oxygen species (ROS) production that damage tumor cells and vasculature. The resulting effect is a balance between photo-oxidations via primary or secondary ROS and scavenging activity. Sensitizers distribute in the extra-cellular space before and during cell sensitization, suggesting that PDT could act directly on cell structures and on extra-cellular compartments, including sera. In this paper we endeavored to determine whether the application of PDT to culture media could have an effect on cell survival. Culture media (RPMI supplemented with Fetal Calf Serum (FCS)) was incubated with Rose Bengal (RB) and irradiated before being added to cells for various times of contact, as a replacement for untreated media. Treatedmedia reduced cell survival by up to 40% after 30 min of contact for 10 μg/mL of RB and 20 J/cm². This effect was RB or light dose-dependent. The survival reduction observed when adding treated-media was more pronounced when cell doubling time was shorter. Analysis of ROS or peroxide production in treated-media revealed a long-lasting oxidizing activity. Our findings support the hypothesis of a ROS or peroxide-mediated, PDT-induced, delayed cell toxicity

New porphyrin-based photo-sensitizers have been designed, synthesized and characterized that exhibit greatly enhanced intrinsic two-photon absorption. These new photo-sensitizers have been incorporated into triad formulations that also incorporate Near-infrared (NIR) imaging agents, and small-molecule targeting agents that direct the triads to cancerous tumors' over-expressed receptor sites. PDT can be initiated deep into the tissue transparency window at 780-800 nm utilizing a regeneratively amplified Ti:sapphire laser using 100-150 fs pulses of 600-800 mW. Human tumor xenografts of human breast cancer (MDA-MB-231) and both small SCLC (NCI-H69) and NSCLC (A-459) have been successfully treated using octreotate targeting of over-expressed SST2 receptors. In particular, the lung cancer xenografts can be successfully treated by irradiating from the side of the mouse opposite the implanted tumor, thereby passing through ca. 2 cm of mouse skin, tissue and organs with no discernible damage to healthy tissue while causing regression in the tumors. These results suggest a new PDT paradigm for the noninvasive treatment of subcutaneous tumors, including the possibility that the targeting moiety could be matched to individual patient genetic profiles (patient-specific therapeutics).

The purpose of the present study was to evaluate toxicological properties and photodynamic activity of a new ready form of the photosensitizer Photolon (Fotolon) - an ointment for topical use. The data obtained show the use of topicaly applied photosensitizer provides sufficient penetration and accumulation of the active compound in tumor tissue as well as in affected periodontal tissues for the effective PDT. There are several advantages of PDT with topical application of the photosensitizer such as absence of systemic toxic and photosensitive reactions, relatively low cost of the treatment and etc. We have shown that PDT of affected periodontal tissues with local application of Photolon/Fotolon ointment provides an ability of local destruction of microbial cell, located as on the gum surface as in the spatium intercellulare what is extremely important for successful treatment of acute and chronic periodontitis.

The effects of As₄O₆ were studied as adjuvant on photodynamic therapy. As₄O₆ is considered to have anticancer activity via several biological actions such as free radical producing and inhibition of VEGF expression. In vitro experiments, cell proliferation and morphology were determined by MTT assay. Also, quantitative PCR array was performed to study the synergetic mechanism. Additionally, this study was supported by the finding that combination of photodynamic therapy and As₄O₆ shows an inhibition effect of tumor growth in C57BL/6 mice with TC-1 cells xenographs in vivo. Radachlorin and As₄O₆ significantly inhibited TC-1 cell proliferation in a dose-dependent manner (P < 0.05). Antiproliferative effect of combination treatment was significantly higher than those of TC-1 cells treated with either photodynamic therapy or As₄O₆ (62.4 and 52.5% decrease, respectively, compared to photodynamic therapy or As₄O₆ alone, P < 0.05). In addition, cell proliferation in combination of photodynamic therapy and As₄O₆ treatment significantly decreased by 77.4% compared to vehicle-only treated TC-1 cells (P < 0.05). Cell survival pathway (Naip1, Tert and Aip1) and p53-dependent pathway (Bax, p21^Cip1, Fas, Gadd₄5, IGFBP-3 and Mdm-2) were markedly increased by combination treatment of photodynamic therapy and As₄O₆. Besides, the immunology response NEAT pathway (Ly- 12, CD178 and IL-2) also modulated after combination treatment of photodynamic therapy and As₄O₆. This combination effect apparently shows a same pattern in vivo model. These findings suggest the benefit of the combination treatment of photodynamic therapy and As₄O₆ for the inhibition of cervical cancer growth.

The role of photodynamic therapy (PDT) in the treatment of small cancers has been established in several clinical studies. Here, we report on the efficacy of PDT for early inoperable or recurrent non-small-cell lung cancer (NSCLC). Methods and Materials: From June 1989 to November 2004, 40 patients with 50 NSCLC were treated with PDT. Twelve cases were inoperable for medical reasons and were staged as T1N0M0, and 28 had recurrent in situ carcinoma. Patients with residual disease after PDT received definitive radiotherapy and/or brachytherapy. Follow-up ranged from 6 to 167 months (median 43.59). Twenty of the 40 patients received i.v. injections of hematoporphyrin derivative (5 mg/kg), the other 20 had injections of porfimer sodium (Photofrin, 2 mg/kg). An argon dye laser (630 nm wavelength, 200-300 J/cm2) was used for light irradiation in 24 of the 40 patients, a diode laser (Diomed, 630 nm wavelength, 100- 200 J/cm2) in the other 16. Results: PDT obtained a 72% complete response (CR) rate (36/50 treated lesions), that is 27 CR among the 37 Tis carcinomas and 9 among the 13 T1 cases. Kaplan-Meier curves showed a mean overall survival (OS) of 75.59 months (median 91.4 months). Two- and 5- year OS rates were 72.78% and 59.55%. The mean and median survival rates for patients with Tis stage were 86.5 and 120.4 months, respectively (standard error 9.50) and for patients with T1 disease they were 45.78 and 35.71 months, respectively; the difference was statistically significant (P< 0.03). No severe early or late PDT-related adverse events were recorded. Conclusions: PDT is effective in early primary or recurrent NSCLC, resulting in a CR rate of 72%. The incorporation of PDT in standard clinical practice, in combination with radiotherapy, warrants further investigation.

Light dosimetry for photodynamic therapy requires a knowledge of the optical absorption spectrum of the tissue being treated Here, we present a theoretical and experimental analysis of the capabilities of a system using interstitial linear light sources ranging in length from 2 to 5 cm to illuminate the tissue interstitially, and isotropic point-like detectors to measure the resulting diffusely transmitted light. The sources and detectors are translated in transparent plastic catheters under the control of a motorized positioning system designed for interstitial measurements in the prostate. The light source is a quartz-tungsten-halogen (QTH), and the spectrally resolved detection is accomplished using a CCD-based grating spectrometer. The data are analyzed using an approximation to the radiative transport equation, assuming homogeneous scattering and heterogeneous absorption spectra Absorption spectra are reconstructed independently for individual source-detector channel pairs. Sequential reconstruction can then be used to create a 3-dimensional reconstruction. The results of simulated data, measurements made in multi-component phantoms, and synthetic data reconstructed from in vivo measurements made with point sources demonstrate the feasibility of this method.

The consumption of singlet oxygen quenchers during illumination of cells incubated with photosensitizers is a serious issue for the determination of singlet oxygen kinetics in cells. Using LNCaP cells incubated with pheophorbide a it will be shown, that already an illumination of 100 nJ/cell dramatically changes the value of the observables. This finding has consequences for the spatial resolution of any time-resolved singlet oxygen measurement, since the radiative rate constant of singlet oxygen in aqueous solutions is very small.

In this paper we describe the development and testing of instruments to measure singlet molecular oxygen produced by the photodynamic process. Singlet oxygen is an active species in photodynamic therapy, and we are developing two instruments for PDT researchers with the goal of a real-time dosimeter for singlet oxygen. We discuss both an ultrasensitive point sensor, and an imaging system that provides simultaneous 2D maps of the photosensitizer fluorescence and the singlet oxygen emission. Results of in vitro tests to characterize the sensors and preliminary in vivo results are presented.

Fluorescence cystoscopy has been recently acknowledged as a useful method to detect early superficial bladder cancer, even flat lesions. After the instillation of hexaminolevulinic acid (Hexvix) in the bladder for about an hour, photoactivable porphyrins (PaP), mainly protoporphyrin IX (PpIX) accumulate in the cancerous cells. Although we observe a selective production of PpIX and an outstanding sensitivity of this method, false positive (FP) lesions negatively impact its specificity. Carcinogenesis often combines with angiogenesis, and thus changes in vascular architecture. Therefore, the visualization of the vascular modifications on the fluorescence positive sites is likely to differentiate false and true positive (TP). New methods including high magnification (HM) cystoscopy are being investigated by our group, and will yield a reduced number of biopsies and a better characterization of the fluorescence positive sites. In this study, we are using a dedicated rigid cystoscope, allowing conventional magnification during "macroscopic" observation, as well as image acquisition with HM when the endoscope is in contact with the tissue. Each observed site is biopsied and described by histopathological analysis. The vascular organization (tortuosity, vascular loops, vascular area and diameter) of the fluorescence positive sites was characterized in parallel with an in situ visual grading and a dedicated software procedure. We describe here a simple image processing prototype that classifies the HM images into two classes, according to their pixel distributions. For that purpose, we developed an algorithm in the image spatial and frequency domain, so that the vascular architecture could be described objectively and quantitatively.

We present a novel way of optical detection of malignant cancer cell colonies by using multi-wavelength two-photon excited fluorescence from an environmentally sensitive Styryl-9M dye. We show that the two-photon excited fluorescence from colonies embedded in a tissue phantom depends on the type of cells as well as on the composition of the phantoms. We use the ratio between the fluorescence intensities excited at 1100 and 1200 nm to distinguish between samples containing no cell colonies, samples with colonies of normal cells and samples with cancer cells. The proposed method is a promising tool for non-invasive deep tissue photodetection diagnostics and for precise localization of malignant cells.

A compact robotic platform is designed for simultaneous multichannel motion control for light delivery and dosimetry during interstitial photodynamic therapy (PDT). Movements of light sources and isotropic detectors are controlled by individual motors along different catheters for interstitial PDT. The robotic multichannel platform adds feedback control of positioning for up to 16 channels compared to the existing dual-motor system, which did not have positioning encoders. A 16-channel servo motion controller and micro DC motors, each with high resolution optical encoder, are adopted to control the motions of up to 16 channels independently. Each channel has a resolution of 0.1mm and a speed of 5cm/s. The robotic platform can perform light delivery and dosimetry independently, allowing arbitrary positioning of light sources and detectors in each catheter. Up to 16 compact translational channels can be combined according to different operational scheme with real-time optimal motion planning. The characteristic of high speed and coordinating motion will make it possible to use short linear sources (e.g., 1- cm) to deliver uniform PDT treatment to a bulk tumor within reasonable time by source stepping optimization of multiple sources simultaneously. Advanced robotic control algorithm handles the various unexpected circumstance in clinical procedure, e.g., positiontorque/ current control will be applied to prevent excessive force in the case of resistance in the fiber or motorized mechanism. The robotic platform is fully compatible with operation room (OR) environment and improves the light delivery and dosimetry in PDT. It can be adopted for diffusing optical tomography (DOT), spectroscopic DOT and fluorescent spectroscopy.

Aminolevulinic acid-mediated photodynamic therapy (ALA-PDT) is an emerging treatment for cancers. ALA, given as a prodrug, selectively accumulates and is metabolized in cancer cells to form protoporphyrin IX (PpIX). Targeted local irradiation with light induces cell death. Since the efficacy of ALA-PDT for large or deep tumors is currently limited, we are developing a new approach that combines differentiation-inducing agents with ALA-PDT to improve the clinical response. Here, we tested this new combination paradigm in the following two models of skin carcinoma in mice: 1) tumors generated by topical application of chemical carcinogens (DMBA-TPA); 2) human SCC cells (A431) implanted subcutaneously. To achieve a differentiated state of the tumors, pretreatment with a low concentration of methotrexate (MTX) or Vitamin D (Vit D) was administered for 72 h prior to exposure to ALA. Confocal images of histological sections were captured and digitally analyzed to determine relative PpIX levels. PpIX in the tumors was also monitored by real-time in vivo fluorescence dosimetry. In both models, a significant increase in levels of PpIX was observed following pretreatment with MTX or Vit D, as compared to no-pretreatment controls. This enhancing effect was observed at very low, non-cytotoxic concentrations, and was highly specific to cancer cells as compared to normal cells. These results suggest that use of differentiating agents such as MTX or Vit D, as a short-term combination therapy given prior to ALA-PDT, can increase the production of PpIX photosensitizer and enhance the therapeutic response of skin cancers.

Photodynamic therapy (PDT) leads to oxidative damage of cellular macromolecules, including numerous proteins that undergo multiple modifications such as fragmentation, cross-linking and carbonylation that result in protein unfolding and aggregation. Several mechanisms are involved in the protective responses to PDT that include activation of transcription factors, heat shock proteins, antioxidant enzymes and antiapoptotic pathways. Identification of these cytoprotective mechanisms might result in the design of more effective combination strategies to improve the antitumor efficacy of PDT. By using various molecular biology approaches, including microarray-based technologies we have identified genes that are up-regulated following PDT. Subsequent experiments revealed that some of these gene products can become targets for the combined therapeutic regimens encompassing PDT and selective small-molecule inhibitors. These include superoxide dismutase (SOD-2), cyclooxygenase 2 (COX-2), heme oxygenase 1 (HO-1), and proteins engaged in signaling endoplasmatic reticulum (ER) stress and unfolded protein response (UPR). Since a major mechanism for elimination of carbonylated proteins is their degradation by proteasomes, we hypothesized that a combination of PDT with proteasome inhibitors might lead to accumulation of carbonylated proteins in ER, aggravated ER stress and potentiated cytotoxicity towards tumor cells. Indeed, we observed that incubation of tumor cells with three different proteasome inhibitors, including bortezomib, MG132 and PSI gave increased accumulation of carbonylated and ubiquitinated proteins in PDT-treated cells. Proteasome inhibitors effectively sensitized tumor cells to PDT-mediated cytotoxicity and augmented antitumor effects of PDT in vivo.

The effect of PDT on ATP level in the Leukemic monocyte lymphoma cell line (U937) was studied using two different photosensitizers, PpIX and Hypericin. U-937 cells were irradiated (with and without ALA) and stored at room temperature. An LED lamp with a maximum peak of 637nm was used for ALA-PDT as a light source. A Na-Li lamp with a wavelength region of 560-730nm was used for Hypericin-PDT as a light source. We measured cell viability, the number of viable cells and ATP luminescence. As a result, it is evident that the irradiation time in the most effective PDT is equal to the time of the highest ATP level in the cells in ALA-PDT. This study suggests that it is possible to obtain suitable PDT conditions inducing apoptosis by measuring the ATP level in ALA-PDT. On the other hand, ATP level in Hypericin-PDT was increased with the decreasing in the cell viability. Hypericin-PDT induced apoptosis just after irradiation.

The present study aimed at comparing the photo detection of peritoneal micrometastases in an ovarian cancer model following administration of two precursors of protoporphyrin IX (PpIX): aminolevulinic acid (ALA) and hexylester aminolevulinate (He-ALA). ALA or He-ALA (100mg/kg) was injected in the peritoneum cavity of 16 rats with induced peritoneal metastases of ovarian cancer. Two hours later, the tumours were visualized laparoscopically using both white light for standard exploration and blue light for fluorescence (D-light, Karl Storz, Tuttlingen, Germany). Peritoneal micrometastases were counted. The distribution of PpIX through the peritoneum was studied on frozen biopsies using fluorescence microscopy and correlated with pathological findings. The number of micrometastases detected by the fluorescence blue mode was significantly higher (p<0.05) than with standard white light for both ALA (235 versus 198) and He-ALA application (248 versus 199). The mean fluorescence intensity ratio between tumor and normal surrounding tissue was significantly (p< 0.05) higher for He-ALA (1.6±0.1) compared to ALA (1.4±0.1). Fluorescence microscopy confirmed that the fluorescence remained limited to cancer cells. Macroscopically fluorescing nodules were histopathology confirmed as malignant. In conclusion, He-ALA is an excellent precursor for PpIX synthesis giving the highest PpIX fluorescence contrast between normal and tumoral peritoneum. Imaging with He-ALA improves the detection of peritoneal metastases comparing to ALA.

Photodynamic therapy (PDT) using protoporpyrin IX (PpIX) precursors like 5-aminolevulinic acid (ALA) or methyl-aminolevulinate (MAL) has shown to be effective in the treatment of various skin diseases. Using ALA we have shown in numerous studies a significantly improved efficacy by applying light fractionation with a long dark interval. In contrast, in the hairless mouse model, the PDT efficacy using MAL is unaffected by adopting this approach. More acute edema is found after ALA-PDT suggesting a difference in response of endothelial cells to PDT. To investigate the role of endothelial cells, cryo-sections of hairless mouse skin after 4 hours of topical MAL or ALA application were stained with a fluorescent endothelial cell marker (CD31). Co-localization of this marker with the PpIX fluorescence was performed using the spectral imaging function of the confocal microscope. We have also used intra-vital confocal microscopy to image the PpIX fluorescence distribution in correlation with the vasculature of live mouse skin. Our results show PpIX fluorescence at depth in cryo-sections of mouse skin after 4 hours of topical application. Co-localization has shown to be difficult due to the changes in tissue organization caused by the staining procedure. As expected we found high PpIX fluorescence levels in the epidermis after both MAL and ALA application using intra-vital microscopy. After ALA application more PpIX fluorescence was found deep in the dermal layer of the skin than after MAL. Furthermore we detected localized fluorescence in unidentified structures that could not be correlated to blood vessels or nerves.

Background: There are few data available comparing endoscopic ablation methods for Barrett's esophagus with high-grade dysplasia (BE-HGD). Objective: To determine differences in symptoms and complications associated with endoscopic ablation. Design: Prospective observational study. Setting: Two tertiary care centers in USA. Patients: Consecutive patients with BE-HGD Interventions: In this pilot study, symptoms profile data were collected for BE-HGD patients among 3 endoscopic ablation methods: porfimer sodium photodynamic therapy, radiofrequency ablation and low-pressure liquid nitrogen spray cryotherapy. Main Outcome Measurements: Symptom profiles and complications from the procedures were assessed 1-8 weeks after treatment. Results: Ten BE-HGD patients were treated with each ablation modality (30 patients total; 25 men, median age: 69 years (range 53-81). All procedures were performed in the clinic setting and none required subsequent hospitalization. The most common symptoms among all therapies were chest pain, dysphagia and odynophagia. More patients (n=8) in the porfimer sodium photodynamic therapy group reported weight loss compared to radio-frequency ablactation (n=2) and cryotherapy (n=0). Four patients in the porfimer sodium photodynamic therapy group developed phototoxicity requiring medical treatment. Strictures, each requiring a single dilation, were found in radiofrequency ablactation (n=1) and porfimer sodium photodynamic therapy (n=2) patients. Limitations: Small sample size, non-randomized study. Conclusions: These three endoscopic therapies are associated with different types and severity of post-ablation symptoms and complications.

Photodynamic therapy(PDT) has been demonstrated to effectively kill human periopathogens in vitro. To evaluate the efficacy of PDT in vivo a series of clinical trials was carried out in multiple centers and populations. Clinical parameters including clinical attachment level, pocket probing depth and bleeding on probing were all evaluated. All groups received the standard of care, scaling and root planing, and the treatment group additionally received a single treatment of PDT. Of the total 309 patients and over 40,000 pockets treated in these 5 trials it was determined that photodynamic therapy provided a statistically significant improvement in clinical parameters over scaling and root planing alone.

The short and long term stability of the Diomed 630 PDT laser with attached fiberoptic microlens was evaluated by means of integrating sphere, power meter and a calorimetric system. The calorimeter system was designed as a thermal mug with absorbing media (dye and water). Both the tip of the irradiation fiber and the detection probe of a thermocouple thermometer were positioned inside the dye solution and stirred during the measurements. The calorimetric system yielded measurement results consistent with the other two methods, and similar long term variations were observed by all methods. With an indicated laser power of 1 W, the detectors' readings ranged from 0.66 to 1.29 W. For short term stability study, the deviation of laser output assessed by integrating sphere, power meter and calorimetric system were 0.3%, 0.1% and 2.8% with long term deviations of 13%, 7% and 9% respectively. This wide variation in the laser output implies the needs to establish quality control procedures involving measurements pre and post PDT procedures. The calorimetric system has been demonstrated to be a powerful tool for clinical laser QA and maintenance of the calibration factor of the detectors used in this work.

In PACT, a combination of a sensitising drug and visible light cause the selective destruction of microbial cells via singlet oxygen production. As singlet oxygen is a non-specific oxidizing agent and is only present during illumination, development of resistance to this treatment is thought to be unlikely. However, in response to oxidative stress, bacteria can up-regulate oxidative stress genes and associated antibiotic resistance genes. The up-regulation of these genes and potential transfer of genetic material may result in a resistant bacterial population. This study determined whether treatment of clinically isolated meticillin resistant Staphylococcus aureus (MRSA) strains with sub-lethal doses of methylene blue (MB) and meso-tetra (N-methyl-4-pyridyl) porphine tetra tosylate (TMP)-PACT resulted in reduced susceptibility to antibiotics and previously lethal PACT. Exposure of strains to sub-lethal doses of photosensitizer in combination with light had no effect on susceptibility to previously lethal photosensitization. Furthermore, exposure to sub-lethal concentrations of both photosensitizers caused no significant changes in the minimum inhibitory concentration (MIC) for each strain tested. Any differences in susceptibility were not significant as they did not cross breakpoints between resistant and susceptible for any organism or antibiotic tested. Therefore, PACT remains an attractive alternative option for treatment of MRSA infections.

To determine factors that govern the uptake preference of photosensitizers in cellular organelles of human adenocarcinoma cells, diarginyl-dialkoxy- and diarginyl-dimethoxyphenylporphyrins (TPPs) and two of their corresponding indium(III) complexes were synthesized, characterized and incubated in androgen-sensitive human prostate adenocarcinoma cells LNCaP. The porphyrins revealed properties that are of importance for phototherapy. They are water-soluble, have their fourth Q-band absorbing at ≈ 650 nm, are taken up in relatively high concentrations in LNCaP cells, and are phototoxic. Colocalization and phototoxicity studies revealed that all porphyrins localized preferentially to the lysosomes and invoked cell death when excited with 650 nm light. Compared to the corresponding methoxy-substituted TPPs, the diargininyl-dialkoxy-substituted porphyrins localized to a small extent in the mitochondria. The corresponding In(III) chloride complexes that are slightly less water-soluble were also taken up in the lysosomes of LnCaP cells. When the TPPs were compared to a pheophorbide derivative recently synthesized in our laboratory, it was determined that the TPPs have a preference for lysosomal localization, whereas the pheophorbide derivative co-localized to the mitochondria. Phototoxicity studies revealed that the longer chain dialkoxyTPPs were more effective in cell killing and induced greater morphological changes typical of apoptotic cell death than the shorter chain methoxy substituted porphyrins. The In(III) complexes seemed to be the most phototoxic. These results highlight that the type, nature, and substitution pattern of the chromophore modulate the extent of apoptotic cell death and influence cellular targeting.

Vascular targeting photodynamic therapy (vPDT) is currently in clinical trial for prostate cancer (PCa) treatment. In order to study the effect of vPDT on tumor metastasis, GFP-PC3 or PC-3 xenografts were treated with verteporfin (BPD) PDT. Vascular function was assessed by ultrasound imaging; lymph node and lung metastasis were assessed by fluorescence imaging. vPDT significantly reduced tumor blood flow within 30minutes to 2 hours of treatment. Sub-curative treatment resulted in re-perfusion within 2 weeks of treatment and increased lymph node metastasis. With curative doses, no metastasis was observed. In order to identify cellular or matrix factors and cytokines implicated, conditioned medium from BPD PDTtreated endothelial cells was incubated with PC3 cells in vitro. Tumor cell proliferation and migration was assessed. By immunoblotting, we evaluated the change in mediators of intracellular signaling or that may determine changes in tumor phenotype. Low sub-curative dose (200ng/ml BPD) of endothelial cells was associated with ~15% greater migration in PC3 cells when compared with control. This dose was also associated with sustained activation of Akt at Ser 473, an upstream effector in the Akt/ mTOR pathway that has been correlated with Gleason scores in PCa and with survival and metastasis in vitro and in vivo. In conclusion, the study implicates efficacy of PDT of endothelial cells as an important determinant of its consequences on adjacent tumor proliferation and metastasis.

One of the limitations of PDT in the treatment of bulk tumors is the light penetration in biological tissues at the red spectrum. PDT illumination at short pulsed regime may present a higher light penetration compared to the CW regime, and potentially a higher volume of induced necrosis. The major goal of this study was an in vitro and in vivo evaluation of PDT response after illumination using a 630 nm femtosecond laser. Photogem in distilled water solution was illuminated either with CW or femtosecond laser under the same fluence and fluence rate parameters. Wistar rats weighting between 280 and 300 g were intravenously photosensitized with Photogem. Thirty minutes after drug injection, the normal liver was irradiated either with the CW or the femtosecond laser (fluence: 150 J/cm²). The in vitro results showed that, under the same conditions, the degradation rate evaluated via fluorescence spectroscopy was higher under femtosecond laser irradiation. Histological analysis of the induced necrosis showed that there was a significant higher depth of necrosis when the femtosecond laser was used. Based on these results, femtosecond lasers seem to be an alternative in PDT applications, improving results for the treatment of lesions for which a larger light penetration is required.

We have proposed non-thermal electrical conduction block for atrial fibrillation treatment by the photosensitization reaction, in which the interval time between the photosensitizer injection and irradiation is less than tenth of that in conventional way. To study the mechanism of photosensitization reaction-induced electrical conduction block, intracellular Ca²⁺ concentration change in rat myocardial cells was measured by fluorescent Ca²⁺ indicator Fluo-4 AM with confocal laser microscopy. Measured rapid increase in the fluorescence intensity and a change in cell morphology indicated that cell membrane damage; that is Ca²⁺ influx and eventually cell death caused by the photosensitization reaction. To demonstrate myocardial electrical conduction block induced by the photosensitization reaction, surgically exposed porcine heart under deep anesthesia was used. The myocardial tissue was paced with a stimulation electrode. The propagated electrical signals were measured by bipolar electrodes at two different positions. Thirty minutes after the injection of 5-10 mg/kg Porfimer sodium or Talaporfin sodium, the red laser light was irradiated to the tissue point by point crossing the measuring positions by the total energy density of less than 200 J/cm². The electrical signal conduction between the measuring electrodes in the myocardial tissue was delayed by each irradiation procedure. The electrical conduction delay corresponded to the block line length was obtained. These results demonstrated the possibility of non-thermal electrical conduction block for atrial fibrillation treatment by the photosensitization reaction.

Human papillomavirus (HPVs) are a family of sexually viruses with over 100 different genotypes identified till date. They are associated in 99% of cervical cancers, with HPV16 found in about 50% of cases. They are a cause of the second most common female cancer worldwide. PDT may constitute an alternative treatment for condyloma by HPV. In this work we present the development of a PDT device specifically designed for the treatment of vulvar and vaginal lesions induced by HPV. This equipment has been used in a clinical protocol and it is optically based on 640 nm LED (light emitting diodes) arrays. There are three illumination probes available that were anatomically designed for specific site applications: a 30 mm x 115 mm diffuser cylinder for intravaginal illumination and uniform irradiance of 42 mW/cm²; a 36 mm circular probe with 118 mW/cm² and a 74 mm circular probe with 57 mW/cm², both for external illumination. The 10% aminolevulinic acid cream is topically placed over the lesions and 4-6 hours after the application the illumination is performed. The illumination time is set depending on the chosen probe and treatment area to achieve a fluence of 200 J/cm². In this presentation, the preliminary results of this clinical trial will be presented.

This study aims at designing and evaluating light source devices that can stably generate light with various wavelengths in order to make possible PDD using a photosensitizer and diagnosis using auto-fluorescence. The light source was a Xenon lamp and filter wheel, composed of an optical output control through Iris and filters with several wavelength bands. It also makes the inducement of auto-fluorescence possible because it is designed to generate a wavelength band of 380-420nm, 430-480nm, and 480-560nm. The transmission part of the light source was developed to enhance the efficiency of light transmission. To evaluate this light source, the characteristics of light output and wavelength band were verified. To validate the capability of this device as PDD, the detection of auto-fluorescence using mouse models was performed.

Background and Objectives: The paper aim was to evaluate the efficacy of the fluorescence spectroscopy in the detection of UV-induced skin change of Wistar rats. Study Design/ Materials and Methods: In a group male Wistar rats, the skin damage was produced by an UV-C lamp, periodically monitored using the laser-induced fluorescence, until complete healing process. After determining a characteristic emission band present in the fluorescence spectra of the induced injuries, the amplitude band monitoring allowed the follow up on the injury and the recovery. Results: We observed the appearance of two new emission bands more evident at the injury spectra when compared to the spectrums from normal non-exposed tissue. Following such spectral bands was possible to observe the establishment and recovery. Conclusions: The fluorescence spectroscopy is a promising technique in distinguishing between normal and UV induced skin change helping the evaluation of changes which are irreversible cancer tissue characteristics.

We demonstrated a possibility of electrical conduction block by ex vivo and in vivo experiments using rat models to establish a non-thermal treatment for atrial fibrillation by photosensitization reaction (PR). One hour after the injection of 2 mg/kg Talaporfin sodium to Wistar rat, the right ventricle (1.4 mmT) was extracted. Paced with a stimulation electrode, this tissue was placed in a tissue bath and immersed in irrigated Tyrode's solution of 37°C with 8 μg/ml Talaporfin sodium and the gas mixture bubbling of 95% CO₂ and 5% O₂. The propagated electrical signal was measured by two bipolar electrodes. Exciting light of 670 nm in wavelength was irradiated to the tissue between the bipolar electrodes by the power density of 1 W/cm². After this irradiation, propagation signal blockade was obtained and continued up to three hours. Rat atrioventricular (AV) node was employed as a target region for chronic model. The heart of Wistar rat was surgically exposed. External four-lead electrocardiogram of this rat was measured. Thirty minutes after the injection of 10 mg/kg Talaporfin sodium to the rat, exciting light of 663 nm in wavelength was irradiated to the AV node by the power density of 500 mW/cm² for ten minutes. Acute AV block was obtained during the irradiation. Two weeks after this procedure, complete AV block was confirmed. The rat was sacrificed to obtain the tissue specimen. We found that the AV node was replaced by scarring tissue under the microscopic observation of the specimen. We verified possibility of permanent electrical conduction block using PR.

Pancreatic cancer is an aggressive disease with a poor prognosis, usually treated with chemoradiation therapy. Interstitial photodynamic therapy is a potentially effective adjuvant treatment that is under development. In the current study, two orthotopic pancreatic cancer models (AsPC-1 and Panc-1), have been characterized with respect to growth rates, morphology and liposomal drug (Verteporfin) uptake and distribution in SCID mice. Fluorescence of Verteporfin was measured in liver and tumor in vivo using a PDT fluorescence dosimeter with measurements taken before and up to one hour after tail vein injection. Fluorescence reached a plateau by about 15 minutes and did not decrease over the first hour. At time points from 15 minutes to 24 hrs, the internal organs (kidney, spleen, pancreas, tumor, muscle, lung, liver, and skin were excised and scanned on a Typhoon imager. The ratio of fluorescence in tumor versus normal tissues was analyzed with image processing, calculated at each time point and compared to in vivo results. Tissue distribution of Verteporfin in relation to functional vasculature marked by DiOc7 was carried out on frozen sections. Final analysis will result in determination of the ideal time point to administer light to achieve maximum tumor destruction while preserving normal tissue.

Oral and skin cancers constitute a major global health problem that cause great impact in patients. The most common screening method for oral cancer is visual inspection and palpation of the mouth. Visual examination relies heavily on the experience and skills of the physician to identify and delineate early premalignant and cancer changes, which is not simple due to the similar characteristics of early stage cancers and benign lesions. Optical imaging has the potential to address these clinical challenges. Contrast between normal and neoplastic areas may be increased, distinct to the conventional white light, when using illumination and detection conditions. Reflectance imaging can detect local changes in tissue scattering and absorption and fluorescence imaging can probe changes in the biochemical composition. These changes have shown to be indicatives of malignant progression. Widefield optical imaging systems are interesting because they may enhance the screening ability in large regions allowing the discrimination and the delineation of neoplastic and potentially of occult lesions. Digital image processing allows the combination of autofluorescence and reflectance images in order to objectively identify and delineate the peripheral extent of neoplastic lesions in the skin and oral cavity. Combining information from different imaging modalities has the potential of increasing diagnostic performance, due to distinct provided information. A simple widefiled imaging device based on fluorescence and reflectance modes together with a digital image processing was assembled and its performance tested in an animal study.

Various problems arising during molecular imaging of different fluoroprobes and metabolites used in PDT can be circumvented by focusing on multifunctional therapy agents. Thus an effective photo sensitizer coupled with other useful roles to play in PDT treatment make nanoparticles as a good vehicle for different delivery assuming multifunctional roles not only in PDT but also as therapeutic agents for targeted delivery. A new approach is the involving use of 100 nm NPs as photo sensitizers and/or imaging agents. In our Lab., we employ two such NPs and are ORMOSIL (organically Modified Silica) and PAA (Polyacrylamide) which are found to be biologically very safe without disturbing the therapeutic value. The size of the nanoparticles determined by TEM and Dynamic Light Scattering are ~30 nm. These NPs are taken up in conjunction with cyanine dye at near infra red as it has been reported in literature that encapsulated NPs shows very low singlet oxygen production compared with the post-loaded NPs though the reasons are not yet clear. Therefore, we investigated the idea of post-loading or adsorbing vis-a-vis encapsulation.

The efficacy of Photodynamic Therapy (PDT) combined with aminolevulinic acid (ALA) or methyl aminolevulinate (MAL) in treatment of cancer has been studied for over ten years. However, there is no established dose for the topical use of these drugs in PDT. The purpose of this study was the comparison of induced PDT response of ALAsense (5-aminolevulinic acid - ALA) and Metvix (methyl aminolevulinate - MAL). Depth of necrosis induced by PDT was analyzed in normal liver of male Wistar rats, using different light doses and topical application of both PpIX precursors - ALA and MAL. PDT was performed with a diode laser at 630 nm with different doses of light (20, 50, 100 and 200 J/cm²), and intensity of 250 mW/cm². Depth of necrosis analysis was used to calculate the threshold dose for each drug. The results showed that MAL-PDT presented a better response than ALA-PDT, mainly due to formulation differences. Moreover, the ability of the ALA PpIX production was more efficient.

Photodynamic therapy (PDT) using topical application of aminolevulinic acid (ALA) and methylaminolevulinate (MAL) has become a popular therapeutic method for the treatment of non-melanoma skin cancers such as basal cell carcinomas (BCCs); however, the treatment response varies. An important question is if BCCs which respond poorly to PDT lack accumulation of protoporhyrin IX (PpIX) after ALA/MAL application. In connection to PDT, fluorescence diagnostics (FD) can be performed to detect PpIX within human skin. We investigated fluorescence images from 22 patients with 35 BCCs. They were evaluated with respect to the fluorescence contrast based on image analysis, which was considered to be a tool to non-invasively measure the PpIX-concentration. As expected the fluorescence contrast between tumor and normal skin was elevated after MAL-application; although no correlation between low fluorescence contrast and lack of treatment response could be observed. In a former study, we have also investigated the transdermal penetration of ALA and MAL in 27 BCCs in vivo using a microdialysis technique. In 15 of 16 BCCs in which the microdialysis catheter was located superficially (i.e. at a depth of less than 1 mm), therapeutic drug concentrations were detected;.however, in the 11 lesions with a deeper catheter location (below 1 mm) drug concentrations above the detection limit of the system were only obtained in 6 lesions (p=0.026). No difference between the transdermal penetration of MAL and ALA could be seen. Conclusions: Lack of PpIX fluorescence cannot entirely explain why some BCCs don't respond to PDT, but inadecuate concentrations within the full thickness of the tumor may play a role as microdialysis has shown.

The objective of this study was to determine the sphingolipid (SL) profile in autophagy-defective cells and overall cell death after PDT with Pc 4 (PDT). Human breast cancer MCF-7 cells with downregulated autophagy protein ATG-7 and their scrambled controls (Scr) were used. Exposure of ATG-7 knockdown cells to PDT led to defective processing of the autophagy marker LC3, and increased overall cell killing. In both cell types PDT evoked an early (2 h) increase in ceramides and dihydroceramides (DHceramides). When the two cell types were compared regarding time (2 and 24 h) and treatment conditions (with and without PDT), the levels of several ceramides and DHceramides were reduced, whereas the concentrations of C14-ceramide, C16-ceramide and C12-DHceramide were higher in ATG-7 knockdown cells. The data imply that the SL profile might be a marker of autophagy-deficiency in cells sensitized to PDT.

Stopping cancer in its path occurs when photosensitizers (PSs) induce apoptotic cell death after their exposure to light and the subsequent formation of reactive oxygen species. In pursuit of our hypothesis that mitochondrial localizing PSs will enhance the efficacy of the photosensitizing process in photodynamic therapy, since they provoke cell death by inducing apoptosis, we synthesized and characterized tetraphenylporphyrins (TPPs) that are substituted at the paraphenyl positions by two amino acids and two fluoro or hydroxyl groups, respectively. They were prepared according to the Lindsey-modified Adler-Longo methodology using trifluoromethanesulfonylchloride (CF₃SO₂Cl) as a catalyst instead of trifluoroacetic acid. The use of CF₃SO₂Cl yielded cleaner products in significantly higher yields. During the synthesis, not only the yields and work-up procedure of the TPPs were improved by using CF₃SO₂Cl as a catalyst, but also a better means of synthesizing the precursor dipyrromethanes was tested by using indium(III) chloride. Column chromatography, HPLC, and NMR spectroscopy were used to separate and characterize the di-amino acid-dihydroxy, or difluoro-substituted porphyrins and to ascertain their purity before subcellular localization studies were carried out. Studies using androgen-sensitive human prostate adenocarcinoma cells LNCaP revealed that certain amino acid substituted porphyrins that are positively charged in the slightly acidic medium of cancer cells are very useful in shedding light on the targets of TPPs in subcellular organelles of cancer cells. Although some of these compounds have properties of promising photosensitizers by revealing increased water solubility, acidic properties, and innate ability to provoke cell death by apoptosis, the cell killing efficacy of these TPPs is low. This correlates with their subcellular localization. The di-amino acid, di-hydroxy substituted TPPs localize mainly to the lysosomes, whereas the di-fluoro-substituted TPPs are trapped in the plasma membrane. Only a pheophorbide derivative recently synthesized in our laboratory localized to the mitochondria of LNCaP cells, which are at the center of cell death as is reflected in their key role during apoptosis, thus reassuring our attempts toward rational drug design.

Photodynamic Therapy (PDT) is emerging as a successful tool to treat both malignant and benign tumors. It involves the interaction of a photosensitizer which upon activation by the appropriate light dose, leads to a cytotoxic and vasculotoxic photodynamic reaction. Improvements in PDT in areas such as the delivery and selectivity of photosensitizers, light-delivery and overall efficacy have helped to increase its attractiveness as an option for therapy. For optimizing the PDT treatment by a "see and treat approach," we have developed a number of tumor avid photosensitizers (PS) namely HPPH-Cyanine dye conjugates or other compounds (Iodinated photosensitizers) which have the ability for Optical and/or PET imaging as well as being effective photosensitizers for treatment. Hyperthermia refers to various techniques of heat application which may be delivered as a single modality or as part of an adjunct treatment option to the existing cancer therapies. Depending upon the temperature range used, hyperthermia might either directly induce cell kill or enhance the efficacy of other treatment modalities. Hyperthermia increases blood flow within the body, which may allow for higher dose delivery of photosensitizers with subsequent increased therapeutic efficacy of PDT. Hyperthermia could also increase the sensitivity of molecular imaging. The use of multifunctional photosensitizers for imaging and PDT is an emerging area and we have developed a few such agents in our lab. We wish to explore the use of hyperthermia to improve the use of such multifunctional photosensitizers from the point of view of imaging and/or therapy. Hyperthermia can be performed either as a whole-body mode or as localized mode. Our goal is to see which of the two heating modalities offers us better outcome.

Photodynamic therapy (PDT) has been reported to be effective for treating various tumors and induce apoptosis in many tumor cells. In this study, we examined a biological significance of PDT with a new photosensitizer, Photodithazine, in a cervical cancer model using TC-1 cells. Also, to see the accumulation level of Photodithazine in tumours, we measured the concentration of Photodithazine at indicated time points in tumours of the mice injected with Photodithazine. When the tumor bearing mice were exposed to varied doses of Photodithazine with laser irradiation (300 J/cm2), retarded tumor growth was significant in mice treated with PDT, as compared to the control group. On the other hand, in the uptake of Photodithazine experiments showed that the highest accumulation of Photodithazine in tumors was shown at 0·5 hr after injection and its concentration was decreased. Photodithazine keeps high concentration values during the first day, Photodithazine showed a rapid clearance from sera as it is relatively long kept by tumor tissue. Taken together, we propose that PDT after the application of Photodithazine may be effective in the mice system.

In this work we described the potentiality of the Hypocrellin B (HB) modified with the presence of lanthanum (La³⁺) ions, in eliminate Candida albicans in suspension. The results showed that the presence of lanthanum ions promotes a red shift of the HB absorption band and an enhancement in singlet oxygen quantum yield in 32%. Also in this work we obtained that the best molar ration between HB and La concentrations was 1:2. No photobleaching was observed in our experimental conditions. Antimicrobial activity was studied exciting C. albicans suspension with a 460 nm LED and a 660 nm laser both with 330 mW/cm² irradiance. Best irradiation time, PS concentration and ROS production profile were determined showing that using 460 nm LED with 10 μM of PS, only 30 s of irradiation time was sufficient to reduce 100 % C. albicans colonies.

In this study, a ratiometric quantification method is developed and applied to monitor mesotetra(hydroxyphenyl) chlorin (mTHPC) pharmacokinetics in the rat skin-fold observation chamber. The method employs a combination of dual-wavelength excitation and dual-wavelength detection. The excitation and detection wavelengths were selected in close to NIR. The first excitation wavelength was used to excite the mTHPC and autofluorescence and the second to excite only autofluorescence, so that this could be substracted. Subsequently the difference was divided by the autofluorescence. Since the method applies division of signal with no mTHPC fluorescence, theory suggests on linear dependency of the method on photosensitizer concentration.

Following Photofrin, the first generation photosensitizer, several second generation photosensitizers have been developed with improved characteristics. More recently, third generation photosensitizers are proposed to achieve higher selectivity toward cancer cells/ tumor tissue. Elevated mitochondrial membrane potential of malignant cells has tested as a tool for preferential uptake of certain photosensitizers to cancer cells. In the same line, we designed new conjugate systems where delocalized cationic moiety delivers a photosensitizer to mitochondria. To prove our concept, two prototype conjugates (TPP-Rh and TPP-AO) were prepared using two cationic dyes (Rhodamine and Acridine Orange) and a photosensitizer (tetraphenylporphyrin, TPP). The two conjugates generated singlet oxygen quite well. Interestingly, the two conjugates showed higher cellular uptake by mover than 8 times than TPP-OH as well as higher phototoxicity. In particular, TPP-Rh showed closer localization pattern to mitochondria than TPP-OH.

Photodynamic therapy (PDT) was employed as a cancer therapy with photosensitizer (PS)-loaded cancer cells, eradicated by the reactive oxygen species after light activation. Cyclo-oxygenase 2 (COX2) is an enzyme expressed in 80% of colon adenocarcinoma and is one of the targets for effective cancer treatment. There is also uprising evidence that the human telomerase reverse transcriptase (hTERT), a catalytic component of telomerase, is reported as a promising indicator for monitoring cancer treatment. In this study, NPe6 mediated PDT on COX2 induced apoptosis in HT-29 was investigated. The cell cycle changes was analysed by flow cytometry and the hTERT expression at pre and post PDT was evaluated at transcription level by Taqman real time PCR. NPe6-PDT in HT-29 cells demonstrated anti-proliferating effect in a drug and light dose dependent manner. LD₅₀ was achieved at 16μg/mL and 2J/cm² at 4 hour-post treatment with a significant down-regulation of COX2 expression at LD₃₀ and LD₅₀ by immunohistochemical staining (IHC) (p<0.05, One-Way ANOVA). Membrane blebbing was detected in over 60% of cells. 35.2% of treated cells arrested in S-phase at LD₅₀ after 24 hours by flow cytometry. A 0.25- and 0.6-fold down-regulation of hTERT mRNA expression was achieved at LD₃₀ and LD₅₀ respectively by TaqMan real-time PCR. To summarize, NPe6 mediated PDT down-regulated COX2 expression and triggered cell apoptosis. The hTERT can serve as an indicative marker for monitoring NPe6-PDT cancer treatment efficacy.

PDT with ALA and MAL is established as a relatively effective treatment for non-melanoma skin cancer and premalignancies. PDT is often repeated, because a single treatment gives poor long term results. Preclinical studies showed that ALA-PDT applying a fractionated illumination scheme with a small first light fraction and a second larger light fraction separated by a dark interval of two hours resulted in a significant increase in efficacy. Whereas the efficacy was not enhanced by fractionating MAL-PDT, indicating that ALA-PDT mechanism is not the same as MAL-PDT mechanism. The increase in efficacy using fractionated PDT was confirmed clinically. A randomized comparative clinical study comparing fractionated ALA-PDT versus non-fractionated ALA-PDT in the treatment of superficial basal cell carcinoma showed a significant higher response rate in the lesions treated with fractionated ALA-PDT after a follow-up of one year ( p<0.002, log-rank test). The five year follow-up is studied at moment. So far the complete response in the group treated with fractionated ALA-PDT seems to be only a few percentages lower compared to the one year follow-up. Besides the gain in response rate, fractionated ALA PDT is cost effective. ALA gel is less expensive than the commercially available MAL (Metvix) and moreover fractionated ALA-PDT takes one treatment day, instead of two treatment days using the Metvix treatment protocol (two MAL-PDT treatments separated by one week), both reducing direct and indirect costs and the burden to the patient.

Photodynamic diagnosis (PDD) exploits the photoactive nature of certain compounds, namely photosensitizers, in order to enhance the visual demarcation between normal and neoplastic tissue. Hypericin is one such potent photosensitizer that preferentially accumulate in neoplastic tissue, and fluoresce in the visible spectrum when illuminated with light of an appropriate wavelength. In our study, we investigated the role of E-cadherin in the selective permeation of hypericin in bladder cancer tissues. Clinical studies were done on a series of 43 histologically graded bladder cancer biopsy specimens, obtained from 28 patients who received intravesical instillations with 8μM hypericin solution for at least 2 hours. Immunohistochemical staining was used to assess the expression of E-cadherin, in the cryosectioned tissues. Hypericin uptake was examined by fluorescence microscopy. Immunohistochemical staining showed a clear expression of E-cadherin along the urothelial lining of the normal and pre-malignant tissues. Partial expression of these cell adhesion molecules were still observed in malignant tissues, however there was a loss of expression to variable extends along the urothelium. Thus, loss of intercellular adhesion can be associated with enhanced hypericin permeation through paracellular diffusion.

Photodynamic therapy (PDT) is a standard treatment for various malignant and non-malignant conditions. Though therapeutic responses are encouraging, recurrences have been noted, as one of the limitations of PDT is treatment-induced hypoxia that triggers angiogenesis. The present study evaluates the use of angiogenic inhibitors Avastin, that targets vascular endothelial growth factor (VEGF) and Erbitux that targets epidermal growth factor receptor (EGFR) with PDT in an in vivo bladder carcinoma xenograft. Tumor bearing mice were assigned to 6 different categories: control, PDT only, Avastin + Erbitux, PDT + Avastin, PDT + Erbitux and PDT + Avastin and Erbitux. Treated and control tumors were monitored for recurrence for up to 90 days. VEGF and EGFR expression was detected in the tumor tissue. Migratory assay was performed to establish the inhibitory effect of the angiogenesis agents. Using confocal laser endomicroscopy, the tumor microvasculature was assessed. Tumors treated with the combination therapy of PDT + inhibitors showed significantly greater response compared to control and PDT only treated group. Combination therapy treated tumors also showed the most post-treatment damage with reduced tumor vasculature. These results demonstrate that the combination of PDT with inhibitors that target different angiogenesis pathways can improve tumor control.

New and resurgent viral and antibiotic-resistant bacterial diseases are being encountered worldwide. The US CDC now ranks hospital acquired infections among the top 10 leading causes of death in the US, costing $20 billion annually. Such nosocomial infections presently affect 5% - 10% of hospitalized patients leading to 2 million cases and 99,000 deaths annually. Until now, assays available to mount comprehensive surveillance of infectious disease exposure by biosecurity agencies and hospital infection control units have been too slow and too costly. In earlier clinical studies we have reported proteomic microarrays combining 13 autoimmune and 26 viral and bacterial pathogens that revealed correlations between autoimmune diseases and antecedent infections. In this work we have expanded the array to 40 viruses and bacteria and investigated a suspected role of human endogenous retroviruses in autoimmune neuropathies. Using scanning laser imaging, and fluorescence color multiplexing, serum IgG and IgM responses are measured concurrently on the same array, for 14 arrays (patient samples) per microscope slide in 15 minutes. Other advantages include internal calibration, 10 μL sample size, increased laboratory efficiency, and potential factor of 100 cost reduction.

Photodynamic therapy (PDT) is a treatment based on the interaction of light, photosensitizing agents and tissue oxygen. The light delivery in PDT is usually optimized by controlling the intensity, the spectrum, and/or the dosage of excitation light. In this paper, we introduce a novel method that aims to improve the efficiency of PDT by controlling the phase of the excitation light, an important and so far neglected parameter. This coherent control approach utilizes the coherence properties of light-matter interaction and aims to manipulate the quantum interferences between various available reaction pathways. In general, an outcome of a photochemical reaction can be optimized by enhancing the desired reaction pathways and suppressing other unwanted pathways. Such optimizations can be done by appropriate tailoring of the electric field profile of a broadband coherent excitation light, i.e. ultrafast laser pulse. Here, we used a femtosecond laser source with adaptive pulse shaping together with a molecular feedback in a learning loop to search for and synthesize such 'smart' laser pulses. Our control objective is to enhance the triplet yield of a model photosensitizer zinc phthalocyanine (ZnPc), which then leads to enhancement of the overall PDT process. We use two coherent control schemes where we optimize the ratio between the excited singlet state (S) and triplet state (T) ZnPc molecules both ways (S/T and T/S). We demonstrate a control of 15% over the triplet yield between the found best and the worst pulse shapes. Our preliminary results show that phase shaping can indeed be used in manipulating photosensitizer photophysics and correspondingly the yield of singlet oxygen.

Accumulating preclinical and clinical evidence supports a pro-oncogenic function for Notch signaling in several solid tumors. Therefore, Notch inhibitory agents, such as gamma-secretase inhibitors (GSI), are being investigated as cancer therapeutic agents and a potential adjuvant to conventional chemo/radiotherapy. To date, no in vitro data are available on the cellular response and effect of either photodynamic therapy (PDT) or GSI on human cholangiocarcinoma (CCA). Consequently, we aimed to study the: (i) constitutive expression of Notch signaling pathway in CCA cell lines; (ii) response to Verteporfin-PDT and to GSI, as single agents on CCA cell lines; (iii) effect of Verteporfin-PDT on Notch signaling pathway expression. Expression of Notch signaling components was studied in two cholangiocarcinoma cell lines, HuCCT1 and TFK-1 (intra- and extrahepatic, respectively). No difference in basal expression of Notch1, 2 and Jagged1 was observed in either cell line. In contrast, Notch3 was found to be weakly and highly expressed in HuCCT1 and TFK-1 cells, respectively - supporting our recent microarray data which showed Notch3 overexpression in biliary brushings from patients with extrahepatic CCA. HuCCT1 and TFK-1 differentially responded to Verteporfin-PDT treatment; preliminary data showed no clear effect of GSI on proliferation/apoptosis in either cell line following short exposure (6 and 24h). Following Verteporfin-PDT, Notch1, 2 and Jagged-1 expression was down-regulated in both cell lines, while Notch3 expression was unaffected in HuCCT1 cells and down-regulated in TFK-1 cells. The Notch signaling pathway could represent a potential target for combination therapy in CCA treatment.

Purpurinimides, derived from chlorophyll-a, are tumor avid, stable in vivo and show a strong absorption in the near IR region (700 nm) with a high singlet oxygen (>50%) producing efficiency. Such a characteristic could be useful in treating large and deeply seated tumors by photodynamic therapy (PDT). These long wavelength photosensitizers can be used as vehicles to deliver the imaging agents to tumors. Therefore, by linking suitable tumor imaging moiety with purpurinimide could produce a novel bifunctional agent, which could possess the desired photo physical properties for both tumor detection as well as photodynamic therapy. Such image guided therapy would represent an archetype for cancer treatment.

The concentration of oxygen and its rate of consumption are important factors playing a role in PDT and radiotherapy. One of the methods for measuring the tissular oxygen partial pressure (pO₂) is based on the use of luminophores presenting an oxygen-dependent quenching of their phosphorescence. The time-resolved luminescence spectroscopy of palladium (PdTCPP) or ruthenium (RuDPP) porphyrin complexes is used for this purpose. Unfortunately, these porphyrin derivatives are phototoxic and leak rapidly out of the blood vessels, making them unsuitable for measuring tissular and or intravascular pO₂. Therefore, this research aimed at developing and testing new biocompatible, non-phototoxic oxygen sensors based on palladium complexes incorporated into oxygen permeable, polysaccharide-based nanoparticles appropriate for noninvasive in situ and in vivo measurements of the pO₂. In vitro studies, performed with an optical fiber-based time-resolved spectrophotometer, showed that the incorporation of such pO₂ probes in nanovectors reduces their sensitivity to oxygen as well as their photobleaching by less than one order of magnitude. However, in vivo biocompatibility studies performed on the chick's embryo chorioallantoic membrane (CAM) model demonstrated that the luminescence of those oxygen probes tends to be heterogeneously distributed within the vasculature. In addition, these probes induce a 'clumping tendency', resulting in a more or less decreased viability of the embryos.

EGFR, a member of the ERBB family, plays a pivotal role in carcinogenesis. EGFR overexpression is implicated in DNA repair and synergistic interactions between EGFR-targeting drugs and conventional chemo/radiotherapy have been reported in preclinical studies for different cancers but not cholangiocarcinoma (CCA). To date there are no in vitro data available on the cellular response and effect of either photodynamic therapy (PDT) or EGFR-targeting drugs on CCA. Therefore, we aimed to study the: (i) response to Verteporfin PDT and to EGFR-targeting drugs, as single agents; (ii) effect of PDT on ERBBs expression, phosporylation status and activation of its signaling pathways; (iii) response to combination of PDT and EGFR-targeting agents. We showed that two cholangiocarcinoma cell lines (HuCCT1 and TFK1 cells, intra- and extrahepatic, respectively) differentially respond to verteporfin-PDT treatment and are resistant to EGFR-targeting agents. A constitutive activation of EGFR in both cell lines was also observed, which could partly account for the observed resistance to EGFR-targeting drugs. In addition, verteporfin-PDT induced further phosphorylation of both EGFR and other Receptor Tyrosine Kinases. Mitochondria-independent apoptosis was induced by PDT in both CCA cell lines; in particular, PDT modulated the expression of members of the Inhibitor of Apoptosis (IAP) family of proteins. Interestingly, there was a PDT-induced EGFR nuclear translocation in both cell lines; co-treatment with either an EGFR-inhibitor (Cetuximab) or a nuclear import blocking agent (Wheat Germ Agglutinin) had an additive effect on PDT cell killing, thus implying a role of EGFR in repairing the potential PDT-induced DNA damage.

We demonstrate a catheter-based complex swept-source optical coherence tomography (SS-OCT) system using a 3x3 Mach-Zehnder quadrature interferometer and an ultra-small optic probe. Design and fabrication of fiber lens for ultrasmall optic probes are presented first. We compare in detail measured performance with expected theoretical performance. Then, we present a 3x3 Mach-Zehnder quadrature interferometer to acquire a complex interferometric signal for SS-OCT. We introduce an unbalanced differential detection method to improve the overall utilization of optical power and provide simultaneous access to the complementary phase components of the complex interferometric signal. No calculations by trigonometric relationships are needed. We compare the performance for our setup to that of a similar interferometer with a commonly used balanced detection technique. We demonstrate complex conjugate artifact suppression of 27 dB obtained in our swept-source optical coherence tomography using our unbalanced differential detection. OCT in vivo and ex vivo images shown in this presentation indicate that our catheter-based complex SS-OCT system is capable for imaging of biomedical tissues and inside organs for human, small animals and big animals.

β-lactamase enzyme-activated photosensitizer (β-LEAP). We aim to exploit drug resistance mechanisms to selectively release photosensitizers (PSs) for a specific photodynamic antimicrobial effect and reduced host tissue damage. Consequently, the fluorescence emission intensity of the PSs increases and allows for the detection of enzyme activity. In this work we sought to evaluate β-LEAP for use as a sensitive molecular probe. We have reported the enzyme specific antibacterial action of β-LEAP. Here we report the use of β-LEAP for the rapid functional definition of a β-lactamase.

Oral cancers are currently diagnosed using white light endoscopy and histopathology. However, oral tumours are mostly superficial and can be difficult to visualise. Here we present the use of hypericin with fluorescence endoscopy and laser confocal fluorescence endomicroscopy interfaced with embedded computing for the diagnosis of oral cancers. Fluorescence imaging of oral lesions was carried out in the clinic using a fluorescence endoscope. The images were analyzed to extract the red to blue (R/B) ratios to discriminate between tissue types. The results showed that the R/B ratio is a good image parameter to discriminate between normal, hyperplastic and malignant oral tissue. We are also developing an embedded, real-time computing system interfaced to a fluorescence endomicroscope for 3D visualization of tumors, where synchronization of cross-sectional image grabbing and Z-depth scanning is realized through programming a Field-Programmable Gate Array. In addition to the programming task, a proprietary control circuit has been developed for the automated 3D reconstruction of fluorescence sections; and preliminary results from fluorescent samples have demonstrated the potential of this system for real-time in vivo 3D visualization of tumours. This will ultimately enable same-day clinical diagnosis to be achieved and further enhance the clinical usefulness of fluorescence diagnostic imaging.

The purpose of the present study was to summarize data on the long-term efficacy of photodynamic therapy (PDT) with Photolon in patients with malignant tumors of various types and localizations. The data obtained show that PDT with Photolon is a highly effective therapeutic modality for the treatment of skin tumors, cervical intraepithelial neoplasias, lung cancers, disseminated forms of melanoma, primary and metastatic brain tumors, several ophthalmologic diseases. This paper provides a review of most illustrative studies of the application of PDT with Photolon for the treatment of different oncological and non-oncological diseases performed in leading clinical centers of the Republic of Belarus and Russia.

Singlet Oxygen (¹O₂) Luminescence Dosimetry (SOLD) and fluorescence photobleaching are being investigated as dosimetric tools for clinical PDT. Both have been applied during superficial ALA-PDT of normal skin and skin cancers. The interpretation of fluorescence and SOLD data is complicated by the non-uniform distribution and bleaching of PpIX and the absorption and scattering of light in the skin. The aim of the present work was to tackle these challenges using Monte Carlo (MC) simulations. Skin was modeled as a three-layer semi-infinite medium with uniform optical properties in each layer. The initial depth-dependent distribution of PpIX was an exponential decay and, after the delivery of each treatment fluence increment, standard photochemical reaction kinetics were used to update the distribution of sensitizer and reacted singlet oxygen. Oxygen depletion due to photochemical consumption or vascular shutdown was also incorporated in the model. The adjoint method was applied to calculate the PpIX fluorescence and 1270 nm singlet oxygen luminescence reaching the skin surface in each time increment. The time-resolved evolution of the fluorescence and cumulative SOLD signals during treatment were compared to the time-resolved volume-averaged distribution of reacted singlet oxygen in the dermis layer for typical clinical PDT conditions. Approximate linear relationships were observed over most of the treatment time.

Previous studies have shown that low-dose PDT using 5-aminolevulinic acid (ALA)-induced photoporphyrin IX (PpIX) can induce apoptosis in tumor cells without causing necrosis. In this study we investigated the molecular mechanisms associated with apoptosis after ALA-PDT treatment in two brain glioma cell lines: human U87, and rat CNS-1cells. We used high energy light at a short time (acute PDT) and low energy light at a long time of exposure (metronomic PDT) to treat both cell lines. The cells were treated with 0.25 mM ALA at 5 joules for energy. We found that CNS-1 cells were more resistant to ALA-PDT than U87 cells when treated by both acute and metronomic PDT. To screen possible apoptosis mechanisms associated with acute and metronomic PDT, microarray analysis of gene expression was performed on RNA from glioblastoma cells treated with either acute or metronomic ALA-PDT. Within the set of genes that were negatively or positively regulated by both treatments are tumor necrosis factor receptors. The expression of TNF receptors was investigated further by RT-PCR and western blotting. The apoptosis mechanism of the cell death occurred through different pathways including BCL-2 and TNF receptors, and in part caused by cleaving caspase 3. Interestingly, metronomic ALA-PDT inhibited the expression of LTβR and the transcription factor NFκB. This inhibition was ALA concentration dependent at low concentrations. 

Photodynamic treatment of subcutaneously implanted Colon 26 tumors in BALB/c mice using the aminolevulinic acid (ALA)-induced photosensitizer protoporphyrin IX (PpIX) was shown to be enhanced by the addition of the vascular disrupting agent 5,6-Dimethylxanthenone-4-acetic-acid (DMXAA; Novartis ASA404). DMXAA increases vascular permeability and decreases blood flow in both murine and human tumors. Sufficiently high parenteral DMXAA doses can lead to tumor collapse and necrosis. We have previously reported marked enhancement of antitumor activity when PDT, using either Photofrin or HPPH, is combined with low-dose intraperitoneal DMXAA. We now describe the first attempt to combine topically-applied DMXAA with PDT. For this, DMXAA was applied two hours before PpIX-activating light delivery. PDT with ALA-PDT alone (ALA 20%; 80 J/cm² delivered at 75 mW/cm²) caused a 39% decrease in tumor volume compared to unirradiated controls. Addition of topical DMXAA to ALA-PDT resulted in a 74% reduction in tumor volume. Diffuse correlation spectroscopy (DCS), a non-invasive blood flow imaging method, is being used to understand the mechanism of this effect and to aid in the proper design of the therapy. For instance, our most recent DCS data suggests that the 2-hour interval between the DMXAA and light applications may not be optimum. This preliminary study suggests a potential role for topical DMXAA in combination with PDT for dermatologic tumors.

Medicinal applications of luminescent semiconductor quantum dots are of growing interest. In spite of the fact that their fabrication and imaging applications have been extensively investigated for the last decade, very little is documented on photodynamic action of quantum dots. In this study we demonstrate generation of singlet oxygen and other radical species upon exposure of quantum dots to blue light and therapeutic red light. Extent of radical production can be readily modified by antioxidants. Lay and scientific communities are two sites concerning potential hazards and enthusiastic applications of nanotechnology. Synthesis of quantum dots composed of less toxic materials is of great interest. A new candidate is a ubiquitous element carbon, which on nanoscale exhibits strong photoluminescence.