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Comparative in vitro study on the characteristics of different photosensitizers employed in PDT

Paper ID Volume ID Publish Year Pages File Format Full-Text
31015 44528 2010 8 PDF Available
Title
Comparative in vitro study on the characteristics of different photosensitizers employed in PDT
Abstract

At present a wide range of photosensitizers are employed in photodynamic therapy (PDT) that have very different characteristics. Although, countless in vitro studies on the attributes of photosensitizers do exist, a direct comparison of these substances on one cell line are rare and may contribute to the choice of the optimal photoactive substance for a specific application. We therefore evaluated the properties of six widespread photosensitizers, namely Foscan®, Fospeg®, hypericin, aluminum (III) phthalocyanine tetrasulfonate chloride (AlPcS4), 5-aminolevulinic acid (ALA), and Photofrin® in terms of: (i) cytotoxicity without illumination, (ii) phototoxicity, (iii) cellular uptake and release, and (iv) apoptosis induction in A431 human epidermoid carcinoma cells using comparable illumination regimens. We clearly show that meso-tetrahydroxyphenylchlorin (mTHPC, Foscan®) is a very effective photosensitizer inducing high phototoxicity at very low concentrations. Similar in vitro characteristics and phototoxicity were observed for Fospeg®, the water-soluble formulation of mTHPC. Hypericin, a photosensitizer extracted from plants of the Hypericum genus, is very effective in inducing apoptosis over a wide range of light fluences. AlPcS4 absorbs light of 674 nm wavelength providing a higher penetration depth in tissue. Its hydrophilic character allows for application as aqueous solution. ALA can be administered at very high concentrations without producing cytotoxic effects in the dark. The intracellular concentration of protoporphyrin IX rapidly decreases after withdrawal of ALA, thus minimizing the period of light sensitivity post PDT. Among all photosensitizers Photofrin® has most clinical approvals and serves as standard.

Keywords
Photodynamic therapy; Photosensitizer; A431 human epidermoid carcinoma; Apoptosis induction; Anti-cancer therapy
First Page Preview
Comparative in vitro study on the characteristics of different photosensitizers employed in PDT
Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology B: Biology - Volume 100, Issue 3, 2 September 2010, Pages 173–180
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering