Porphyrin Distribution After Topical Aminolevulinic Acid in a Novel Porcine Model of Sebaceous Skin

Porphyrin Distribution After Topical Aminolevulinic Acid in a Novel Porcine Model of Sebaceous Skin

Author Sakamoto, Fernanda Hidemi Autor UNIFESP Google Scholar
Tannous, Zeina Google Scholar
Doukas, Apostolos G. Google Scholar
Farinelli, William A. Google Scholar
Smith, Nicholas A. Google Scholar
Zurakowski, David Google Scholar
Anderson, R. Rox Google Scholar
Institution Harvard Univ
Universidade Federal de São Paulo (UNIFESP)
Abstract Background and Objective: Aminolevulinic acid photodynamic therapy (ALA-PDT) depends on drug metabolism into porphyrins. Clinically, ALA-PDT has been used with a wide range of protocols for treating both epidermal and dermal targets, despite limited understanding of porphyrin biodistribution over time. We studied porphyrin accumulation after topical application of ALA in vivo, and also describe the porcine ear as a new animal model to study adnexal glands.Study Design/Materials and Methods: the microanatomy of anterior ear skin of swine was measured. Topical 20% ALA in water/ethanol was applied under occlusion. Biopsies taken after 5, 10, 15, and then every 15 minutes for a total of 3 hours were examined by fluorescence microscopy of frozen sections to assess accumulation and distribution of porphyrins.Results: Porphyrin fluorescence of digital photomicrograph images was not visually apparent until 3045 minutes after application, although quantitative pixel analysis showed a statistically significant increase in epidermal fluorescence only 15 minutes after ALA application. From 30 to 120 minutes, epidermis, hair follicles (HF), and sebaceous glands (SG) became progressively more fluorescent. Eccrine gland fluorescence began to be detected after 30 minutes; SG showed fluorescence starting at 45-75 minutes. Fluorescence in all sites reached maximum intensity from 75 to 180 minutes of incubation. There was a trend for HF and SG to express stronger fluorescence compared with epidermis and eccrine glands.Conclusion: Anterior pig ear skin is microanatomically similar to human sebaceous skin. the time-dependent accumulation of porphyrins in pilosebaceous units and eccrine glands in this model suggests other routes of uptake of topical ALA in addition to the trans-epidermal route. Apparently, time interval between ALA application and light exposure could be optimized for different uses of ALA-PDT. Lasers Surg. Med. 41:154-160, 2009. (C) 2009 Wiley-Liss, Inc.
Keywords acne
animal model
apocrine glands
eccrine glands
sebaceous glands
sweat glands
time perception
photodynamic therapy
Language English
Sponsor Wellman Center for Photomedicine in Boston, Massachusetts
Date 2009-02-01
Published in Lasers in Surgery and Medicine. Hoboken: Wiley-liss, v. 41, n. 2, p. 154-160, 2009.
ISSN 0196-8092 (Sherpa/Romeo, impact factor)
Publisher Wiley-Blackwell
Extent 154-160
Origin http://dx.doi.org/10.1002/lsm.20734
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000263897200014
URI http://repositorio.unifesp.br/handle/11600/31257

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