Topical photodynamic therapy following excisional wounding of human skin increases production of transforming growth factor-β3 and matrix metalloproteinases 1 and 9, with associated improvement in dermal matrix organization

S. J. Mills, M. D. Farrar, G. S. Ashcroft, C. E M Griffiths, M. J. Hardman, Lesley Rhodes

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    Abstract

    Background Animal studies report photodynamic therapy (PDT) to improve healing of excisional wounds; the mechanism is uncertain and equivalent human studies are lacking. Objectives To explore the impact of methyl aminolaevulinate (MAL)-PDT on clinical and microscopic parameters of human cutaneous excisional wound healing, examining potential modulation through production of transforming growth factor (TGF)-β isoforms. Methods In 27 healthy older men (60-77 years), a 4-mm punch biopsy wound was created in skin of the upper inner arm and treated with MAL-PDT three times over 5 days. An identical control wound to the contralateral arm was untreated and both wounds left to heal by secondary intention. Wounds were re-excised during the inflammatory phase (7 days, n = 10), matrix remodelling (3 weeks, n = 8) and cosmetic outcome/dermal structure (9 months, n = 9). Production of TGF-β1, TGF-β3 and matrix metalloproteinases (MMPs) was assessed by immunohistochemistry alongside microscopic measurement of wound size/area and clinical assessment of wound appearance. Results MAL-PDT delayed re-epithelialization at 7 days, associated with increased inflammation. However, 3 weeks postwounding, treated wounds were smaller with higher production of MMP-1 (P = 0·01), MMP-9 (P = 0·04) and TGF-β3 (P = 0·03). TGF-β1 was lower than control at 7 days and higher at 3 weeks (both P = 0·03). At 9 months, MAL-PDT-treated wounds showed greater, more ordered deposition of collagen I, collagen III and elastin (all P <0·05). Conclusions MAL-PDT increases MMP-1, MMP-9 and TGF-β3 production during matrix remodelling, ultimately producing scars with improved dermal matrix architecture. What's already known about this topic? Photodynamic therapy (PDT) is reported to enhance skin healing significantly after excisional wounding in animal models. No equivalent studies have been reported in humans. What does this study add? Topical PDT following excisional wounding of human skin leads to increased production of transforming growth factor-β3 and matrix metalloproteinases 1 and 9. This is accompanied by more orderly dermal matrix deposition. The potential further development of topical PDT to enhance healing of excisional wounds is suggested. © 2014 British Association of Dermatologists.
    Original languageEnglish
    Pages (from-to)55-62
    Number of pages7
    JournalBritish Journal of Dermatology
    Volume171
    Issue number1
    DOIs
    Publication statusPublished - 2014

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