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Photodynamic therapy using topically applied hypericin: Comparative effect with methyl-aminolevulinic acid on UV induced skin tumours

Paper ID Volume ID Publish Year Pages File Format Full-Text
30936 44518 2011 9 PDF Available
Title
Photodynamic therapy using topically applied hypericin: Comparative effect with methyl-aminolevulinic acid on UV induced skin tumours
Abstract

Photodynamic therapy (PDT) is a treatment option particularly well-suited for superficial (pre)malignant skin lesions due to the skin’s accessibility to light. In the present study, the efficacy of topical hypericin-PDT was evaluated using a mouse model for actinic keratosis. For comparison, similar experiments were conducted with methyl-aminolevulinic acid (Me-ALA). Small skin tumours (1–2 mm) were induced in hairless mice by chronic UV irradiation. After topical application of hypericin (0.1% in gelcream for 24 h) or Me-ALA (Metvix® for 4 h), the lesional/non-lesional skin surface fluorescence ratio was determined and fluorescence microscopy was used to study the skin penetration of the photosensitizers. The antitumour activity of topical PDT (20 mW cm−2, 40 J cm−2) was evaluated by measurement of the lesional diameters. Moreover, biopsies were taken at various time points after PDT for histological evaluation of the therapy.Our results demonstrate that after topical application of hypericin and Me-ALA, tumour selectivity is limited in mouse skin. The microscopic distribution of hypericin fluorescence showed an accumulation in the stratum corneum and low fluorescence levels in the rest of the lesions, whereas the distribution of PpIX in the skin was more homogenous. Topical hypericin-PDT was found to be less efficient (44% total lesional clearance) as compared to Me-ALA-PDT (80% total lesional clearance). Full lesional necrosis was observed in responsive lesions, and the atypical cells of actinic keratosis were replaced by normal keratinocytes 3 weeks later, both after hypericin-PDT and Me-ALA-PDT.

Keywords
Actinic keratosis; Hypericin; Methyl-aminolevulinate; Photodynamic therapy; Topical application; UV induced skin tumours
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Photodynamic therapy using topically applied hypericin: Comparative effect with methyl-aminolevulinic acid on UV induced skin tumours
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology B: Biology - Volume 102, Issue 2, 7 February 2011, Pages 123–131
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us