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 (AlPcS(4)), 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. AlPcS(4) 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.

• Authors: Juergen Berlanda, Tobias Kiesslich, Victoria Engelhardt, Barbara Krammer, Kristjan Plaetzer
• Journal: Journal of photochemistry and photobiology. B, Biology (J Photochem Photobiol B) Vol. 100 Issue 3 Pg. 173-80 (Sep 02 2010) ISSN: 1873-2682 [Electronic] Switzerland
• PMID: 20599390 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright (c) 2010 Elsevier B.V. All rights reserved.

Chemical References

• Anthracenes
• Antineoplastic Agents
• Indoles
• Mesoporphyrins
• Organometallic Compounds
• Photosensitizing Agents
• aluminum tetrasulfophthalocyanine
• Perylene
• hypericin
• Aminolevulinic Acid
• Dihematoporphyrin Ether
• temoporfin

Topics

• Aminolevulinic Acid (toxicity)
• Anthracenes
• Antineoplastic Agents (toxicity)
• Apoptosis
• Cell Line, Tumor
• Dihematoporphyrin Ether (toxicity)
• Humans
• Indoles (toxicity)
• Mesoporphyrins (toxicity)
• Organometallic Compounds (toxicity)
• Perylene (analogs & derivatives, toxicity)
• Photochemotherapy
• Photosensitizing Agents (toxicity)