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Proceedings Paper

ALA-based photodynamic therapy in epithelial tumors: in vivo and in vitro models
Author(s): Adriana Casas; Haydee Fukuda; Alcira Batlle
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Paper Abstract

PDT shows considerable potential as a treatment modality for superficial tumors. PDT is based on the accumulation of a photosensitizer in the target tissue. Subsequent illumination with light of an appropriate wavelength provokes a photochemical reaction that results in tumor destruction. Aminolevulinic acid (ALA) is a porphyrin precursor, and its administration result in the endogenous production of phototoxic porphyrins, which has been exploited for PDT. We assessed PDT efficacy employing both in vivo and in vitro models. We used papillomas, keratoacanthomas and in situ carcinomas chemically induced in the skin of SENCAR mice. Using ALA lotion and cream formulations, the maximal amount of porphyrin accumulation in papillomas was 5.52 (mu) g/g tissue. An energy of 150 of J/cm2 was delivered by a copper-dye laser tuned at 630 nm. Microscopically, we found several signs of tissue destruction, more markedly in the upper strata of the in situ carcinomas. Papillomas, characterized by hyperkeratinization, were resistant to PDT. In our in vitro studies, we used an epithelial adenocarcinoma cell line. We tested ALA and its hexyl and methyl derivatives with the aim of increasing porphyrin synthesis. We found that hexyl-ALA was the best compound. When cultures incubated 3 hours in 0.6 mM ALA and 0.1 mM hexyl-ALA respectively were irradiated with 3 J/cm2 only 5 percent of cells survived.

Paper Details

Date Published: 29 March 2000
PDF: 10 pages
Proc. SPIE 3909, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy IX, (29 March 2000); doi: 10.1117/12.379888
Show Author Affiliations
Adriana Casas, Univ. of Buenos Aires (Argentina)
Haydee Fukuda, Univ. of Buenos Aires (Argentina)
Alcira Batlle, Univ. of Buenos Aires (Argentina)

Published in SPIE Proceedings Vol. 3909:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy IX
Thomas J. Dougherty, Editor(s)

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