The most important light parameter in LLLT is the dose (amount of light energy), but despite the fact that lasers have been used for almost 50 years for medical applications (McGuff, 1963), there is still no consensus on how to define “dose”. The most common way to present dose is in number of joules per surface unit (for example J/cm2). Unfortunately, it is more complicated than that. We will provide examples illustrating the problems, and we will suggest a schedule of parameters that we will offer all scientific journals publishing articles on LLLT.

The common method for applying LLLT is to aim light at an injury or lesion to promote healing, reduce inflammation or induce analgesia. However there is more to LLLT then just treating stressed cells around a pathology. Nerves, lymph, trigger points and blood are also influenced by light and not just by treating at the site of injury. Many laboratory and clinical research studies have shown that treatments remote from the site of injury produce statistical and clinically meaningful improvements to a range of pathologies. This presentation will be a brief overview of evidence.

LLLT has many applications for central nervous system (CNS) related diseases. In this therapeutic modality light dosimetry is critical. To better understand how light dosage can be delivered to the most relevant neural sites we evaluated optical properties, such as scattering and absorption coefficients, point by point in the rat brain. We obtained these optical properties for red (λ = 660 nm) and near infrared (λ = 808 nm) diode laser analyzing the light penetration and distribution in the whole brain. This study provides remarkable information for LLLT dosimetry in CNS organs.

Low level laser therapy (LLLT) is used in several applications, including the reduction of inflammatory processes. It might be used to prevent surgical complications after cardiopulmonary bypass (CPB) surgery. The objectives were to study light distribution inside blood, in order to implement the LLLT during CPB. Blood diluted to the same conditions of CPB was illuminated and an optical fiber collected the scattered light at 632.8 nm or 820 nm. Compared to the 820 nm, the 632.8 nm light is scattered further away from the laser beam, turning it possible that a bigger volume of blood be treated.

Low level light therapy (LLLT) has been widely reported to reduce pain and inflammation and enhance wound healing and tissue regeneration in various settings. LLLT has been noted to have both stimulatory and inhibitory biological effects and this process has been termed Photobiomodulation (PBM). Several elegant studies have shown the key role of Cytochrome C oxidase and ROS in initiating this process. The downstream biological responses remain to be clearly elucidated. Our work demonstrates activation of an endogenous latent growth factor complex, TGF-β1, as one of the major biological events. TGF-β1 has critical roles in various biological processes such as inflammation and immune responses, wound healing and stem cell biology. This presentation will outline the distinct molecular mechanisms involved in activation of the latent growth factor complex. A broad panel of biochemical, biophysical and biological assays was used in vitro to explore each step of this process. Further, experiments in small animal models were used to establish the in vivo efficacy of this mechanism. While there are clearly demonstrated LLLT effects on both intracellular and extracellular biological molecules, which are dependent on the wavelength and energy density, this presentation will address one of these mechanisms involving LLLT-generated ROS activation of latent TGF-β1. This data highlights the use of PBM to activate an endogenous factor to direct differentiation of native, resident stem cells providing evidence for the use of LLLT as an innovative clinical tool in regenerative medicine.

When exposed to a 1 sec pulse of 2-µm laser radiation 24 hr after illuminating hTERT-RPE cells with red light (preconditioning), the preconditioned cells are more resistant to thermal challenge than unilluminated controls (adaptive response). “Knockdown” cell strains for VEGF-C and miR-146a do not show a significant adaptive response when preconditioned with 1.44 to 5.40 J/cm2, using irradiances between 0.40 and 1.60 mW/cm2, of either 671-nm (diode) or 637-nm (laser) radiation. So far the response does not appear to be dependent upon either wavelength (637 vs. 671 nm) or coherence (laser vs. LED), but there is an irradiance dependence.

Low level laser therapy is a treatment used in several applications; optical magnetic twisting cytometry (OMTC) is a technique used to evaluate mechanical properties in cell culture, elastic shear and loss moduli can be obtained. It was used to investigate if illumination can cause changes in mechanical properties of cells. Samples of human epithelial cells were divided in two groups: a control and an illuminated, with a 660 nm laser. Both moduli increased for illuminated samples, meaning that the cells became tenser. OMTC is a technique which can be used to aggregate knowledge for light effect in cell cytoskeleton.

The understanding of how the association of a photosensitizer and light acts against oral biofilms is still an important goal in antimicrobial PDT field. This study aimed to use confocal microscopy to evaluate different microorganisms and how different photosensitizers (PS) acts and binds to it. For this purpose we characterize a fungus and a bacterium biofilm with Curcumin. The aim of our study was initially to determine how the Curcumin would be distributed through the living biofilm. We realize there was a dynamics throughout the microorganism that can be correlated with the incubation time of the PS.

Several mechanisms have been proposed to explain biological effects of the speckles of laser light going through tissue but no experimental work has been performed. In this work we, for the first time, have experimentally demonstrated stimulation of bacterial growth inhibition by laser with interference pattern of intensity distribution. We measured the growth of Staphylococcus aureus and Peudomonas aeruginosa bacteria in vitro illuminated by interference pattern of laser light. The effect of stimulation of bacterial growth inhibition compared to control was demonstrated. Maximum inhibition of bacterial growth achieved at a spatial frequency of exposure 1000 1/mm. No stimulation of the growth inhibition with homogeneous laser illumination was demonstrated. Potential explanation of photobiomodulation by laser speckles is proposed.

Photodynamic therapy is an alternative antimicrobial treatment for photoinactivation of pathogens. The main purpose of this study was to demonstrate the importance of PDT dosimetry. If the dosimetry of PDT was not optimized properly, photoinactivation of bacteria cannot be achieved and even worse biostimulation on pathogens could be observed. In this study, the biostimulative effect on P. aeruginosa strain was observed instead of the PDT effect, when 84 J/cm2 of light was applied with 20, 50, 100 and 150 μg/ml of ICG. However the killing effect of PDT was not enough to destroy pathogen efficiently with these light dose and ICG concentrations.

We have previously shown that transcranial low level light therapy (LLLT) can ameliorate brain damage in mice subjected to traumatic brain injury and improve neurological function. We used a 810-nm laser and delivered 18 J/cm2 at an irradiance 25 mW/cm2. LLLT was either delivered once at 4 hours after controlled cortical impact TBI, once a day for 3 days, or once a day for 14 days. One and 3 applications of LLLT had beneficial effects on the mice, with 3 being better than 1, but 14 applications had no beneficial effect. We now report immunofluorescence studies in mouse brain sections that offer some explanation for this intriguing finding. Mice were injected with BrdU for 1 week before sacrifice (a marker for proliferating cells) and antibodies to double cortin (DCX-1,a marker of migrating neurons), Tuj-1 ( a marker of neuroprogenitor cells), BDNF (brain derived neurotrophic factor) and synapsin-1 ( a marker for newly formed synaptic connections between existing neurons). We found increased BrdU incorporation indicating proliferating cells in the dentate gyrus of the hippocampus, the subventricular layer of the lateral ventricle, as well as the brain tissue surrounding the cortical lesion. Interestingly these cells were more abundant at 7 days than at 28 days post TBI. Co-labeling of BrdU with Neu-N was performed indicating that the proliferating cells were in fact neuronal in nature. Mice with 3 laser treatments had much more BrdU incorporation than mice with 14. Upregulation of BDNF was seen at 7 days, and increased expression of DCX-1 and Tuj-1 was seen at 28 days in the lesion region, indication that neuroprogenitor cells may have migrated there from sites of neurogenesis. Increased syapsin-1 was seen in the cortex at 28 days indicating that neural plasticity may be stimulated by LLLT. Taken together these data suggest that transcranial LLLT may have applications beyond TBI in areas such as neurodegenerative disease and psychiatric disorders.

Benefits of the isolated use light and biomaterials on bone repair are known. Raman analysis on bone defects grafted or not with Hydroxyapatite - HA, treated or not with LED was carried out. Animals were divided into: GI – clot, GII – HA, GIII – Clot + LED and GIV - HA + LED. LED (λ850 ± 10nm) was applied at 48 h intervals. The peak of HA served as marker of mineralization. Significant difference was observed at both times (p<0.05). HA caused higher peaks and using LED further increased intensity. It is concluded that LED light improved the effect of the HA.

The aim of this study was to analyze in vitro by scanning electron microscopy (SEM) the effect of hydrogen peroxide at 20% at neutral pH, cured by the green LED, to evaluate the action of these substances on dental enamel. We selected 15 pre-molars were hemi-sectioned. Morphological analysis (SEM) performed, and quantitative analysis of the determination of the surface atomic composition. The use of hydrogen peroxide at a concentration of 20% at photoactivated showed no significant changes in composition of the samples or the dental morphological structure.

Leishmaniasis representing a worldwide public health problem. Pentavalent antimonials, have been used in the treatment of leishmaniasis and they exhibit several limitations like severe side effects. Photodynamic Antimicrobial Chemotherapy (PACT) presents itself as a new proposal for a therapy against parasites. We aimed to verify the effectiveness of PACT in vitro, as a new technique for the treatment of Leishmaniasis. We found an important decrease in the number of viable parasites on all treated groups in comparison to their controls. Our results demonstrated significant percentage of lethality (above 95%), even using concentrations below those reported in the literature.

In this study was evaluated the efficacy of laser phototherapy in the prevention and treatment of oral mucositis induced by chemotherapy CMF (cyclophosphamide, methotrexate, 5-Fluouracil) and FAC (5 Fluouracil + Adriamycin + Cyclophosphamide) protocols in breast cancer patients. The patients were divided into 3 groups: A-(FAC + Routine dental protocol + Laser), B-(CMF + Routine dental protocol + Laser), C1-(FAC + Routine dental protocol) and C2-(CMF + Routine dental protocol). The results showed pain relief in 42.86% patients who used the laser as a preventive or therapeutic. It is concluded that the Laser caused immediate pain relief and accelerated healing.

The objective of this study was evaluating the bactericidal effect of PACT using phenothiazine derivatives at a concentration of 1.0µg/mL and red LED at doses of 12J/cm² against S.aureus. This treatment protocol did not show statistically significant mortality between the groups when we analyzed the numbers of bacteria. Though, in the L+P+ group most bacteria present was marked by DHE showing the production of ROS after LED application. Therefore, it was concluded that the phenothiazine compounds when combined with red LED increase the production of ROS in bacteria and therefore can be regarded as promising treatment protocol.

This research explores the role of cytochrome c oxidase (Cco) and nitric oxide (NO) in regulating the response of hTERT-RPE to low-levels of either 637 or 671 nm light (photobiomodulation). Following exposure, intracellular levels of ATP, NF-κB and Bcl-2 all increased relative to unexposed controls, while Bax levels decreased. Exposed cells with inducible nitric oxide synthase (iNOS) inhibited still showed an increase in NO and ATP levels. These data suggest that NO levels are dependent on Cco, supporting the notion that Cco is the primary chromophore in low-level light stimulation and that NO plays a role in the downstream effects.

The objective of this study was to evaluating the PACT bactericidal effect using phenothiazine (concentration=1.0µg/mL) and red LASER at doses of 2.4J/cm² against S.aureus. This research, tests were performed in quadruplicate, with groups: Control; LASER; LASER and phenothiazine (L+P+); only phenothiazine. This treatment protocol did not show statistically significant mortality between the groups when we analyzed the bacteria numbers. Though, in the L+P+ most bacteria were labeled showing the ROS production after LASER application. Therefore, it was concluded that the phenothiazine when combined with LASER increase the ROS production. Therefore it can be regarded as promising treatment protocol

Bone diseases such as osteoporosis are mainly caused by up-regulated activity of osteoclasts. The present study was designed to examine the effects of Low Level Laser Therapy (LLLT) on the formation and activity of multinucleated osteoclasts, specifically ‘round-shaped’ osteoclast cells (ROC) in mouse derived macrophage lineage cell line, RAW264.7. The cells were irradiated by 400~900nm LED arrays during cultures (30mW/cm2 or 2mW/cm2). The cell viability was evaluated by MTT assay. The amount of total TRAP+ osteoclast and the number of ROC cells were estimated by TRAP solution assay and TRAP staining, respectively. Actin rings were stained with rhodamine-conjugated phalloidin, and resorption assay was performed by dentin slices. In addition, gene expression levels between the control and irradiation groups were evaluated by RT-PCR. In a morphological analysis, the formation of ROC was significantly inhibited by 635nm at 2mW/cm2 for 72hrs. Actin rings were seen at cell peripheries in most ROC cells of the control group but patches containing disorganized actin were found in the irradiation group. The number of ROC and bone resorption activity was much lower in the irradiation group than in the control group. Also, the gene expression levels involved in actin ring formation such as integrin β3 and c-Src decreased in RT-PCR analysis. Overall, LLLT using 635nm LED may play a pivotal role in regulating bone remodeling, and it may prove to be a valuable tool for the treatment of bone diseases such as osteoporosis.

To test the hypothesis that photobiomodulation (PBM) would protect against retinal degeneration in a rodent model of retinitis pigmentosa, rat pups were treated with an 830 nm LED array (25 mW/cm2; 4 J/cm2) (QBMI Photomedicine) from p10 to p25. The status of the retina was determined at p30 by ERG and retinal morphology by SD-OCT. PBM preserved retinal function and retinal morphology in treated animals in comparison to the sham-treated group. These findings demonstrate the retinoprotective effects of 830nm PBM and support the use of PBM as an innovative, non-invasive therapeutic approach for the treatment of retinal degenerative disease.

To compare the tissue repair of diabetic ulcers under two systems of delivery of laser light. (1) control group (CG) - no treatment, (2) single dose (SDG) - LLLT two hours after the wound, (3) fractionated dose (FDG) - LLLT on days 0, 3, 8, 10. SDG: 660 nm, 6mW/cm2, 4 J/cm2, 668 s. FDG: four doses of 1 J/cm2, 167 s. Euthanasia at days 0, 3, 8, 10, 14. HE stain and immunohistochemistry to alpha smooth muscle actin, a myofibroblast marker. Quantification of the inflammatory infiltrate, granulation tissue, number of myofibroblasts will be presented.

Laser Immunotherapy is a drug/device combination therapy that utilizes a local intervention to induce a systemic anti-tumor immunity. The two principles underlying LIT are (1) local destruction of tumor cells resulting from direct delivery of laser energy into the tumor, which liberates tumor antigens and in itself induces a local immune response, and (2) local administration of an immunoadjuvant to elicit a much stronger systemic immune response. Here we present a case report of a metastatic breast cancer patient, and we also discuss the importance of using advanced imaging modalities for assessing the response to the treatment.

Wavelength influences the outcome of many clinical protocols. Phototherapies have been used on the treatment of pain including on TMDs. This work reports a series of patients of the Center of Biophotonics (UFBA) over a decade. Following diagnosis, patients scored pain using a VAS and undergone treatment (IR and/or Red light) 3 times a week for 6 weeks without any other intervention. VAS score was recorded again at discharge. Most patients were asymptomatic or improved after treatment. Association of wavelengths was efficient on the symptomatic group. It is concluded that the association was effective on pain reduction on TMDs.