Volume 62, Issue 1 , Pages 85-95, January 2010
Photorejuvenation induced by 5-aminolevulinic acid photodynamic therapy in patients with actinic keratosis: A histologic analysis
Background
Repeated exposure to ultraviolet radiation from the sun results in premature photoaging. Photodynamic therapy (PDT) has been shown to be effective for treatment of photoaging, although the data from most studies have been based on clinical observation.
Objectives
We investigated whether 5-aminolevulinic acid (ALA)-PDT induced histologic changes suggesting photorejuvenation.
Methods
Fourteen patients with one to three actinic keratoses on the face were treated twice with ALA-PDT by using a 1200 W metal halogen lamp at 1-month intervals. Skin biopsy before and 1 month after the PDT was performed. Twenty-five pairs of specimens were obtained. We examined the specimens with routine and immunohistochemical staining and evaluated the parameters associated with photoaging by using image analysis.
Results
After ALA-PDT, the mean epidermal thickness and dermal inflammatory infiltrate were reduced. The total collagen volume in the dermis significantly increased with expression of type I and III procollagen. The level of transforming growth factor β and transforming growth factor β type II receptors in the epidermis also increased. The elastotic material with co-localizing fibrillin-1 and tropoelastin expression in the dermis decreased after treatment. The expression of matrix metalloproteinases-1, -3, and -12 also decreased.
Limitations
The study was limited by the small sample size.
Conclusions
ALA-PDT resulted in histological changes indicating restoration of photoaged skin. These data suggest that ALA-PDT could be effective for photorejuvenation.
Key words: histologic changes, photodynamic therapy, photorejuvenation
Abbreviations used: AK, actinic keratosis, ALA, 5-aminolevulinic acid, ECM, extracellular matrix, MMP, metalloproteinase, PDT, photodynamic therapy, TβRII, TGF-β type II receptor, TGF-β, transforming growth factor β, TIMP, tissue inhibitor of metalloproteinases, UV, ultraviolet
Funding sources: None.
Conflicts of interest: None declared.
PII: S0190-9622(09)00694-X
doi:10.1016/j.jaad.2009.06.025
© 2009 American Academy of Dermatology, Inc. Published by Elsevier Inc All rights reserved.
Volume 62, Issue 1 , Pages 85-95, January 2010

