Molecular changes following topical photodynamic therapy using methyl aminolaevulinate in mouse skin

BackgroundPhotodynamic therapy (PDT) with aminolevulinic acid (ALA) or methyl aminolaevulinate (MAL) has been shown to enhance treatment of photoaged skin. However, there is little information about the molecular changes involved in dermal matrix remodeling following MAL-PDT for photorejuvenation.ObjectiveWe sought to analyze the molecular changes of the epidermal and dermal matrix after MAL-PDT in mouse skin.MethodsSerial biopsy specimens were obtained at baseline and at various times after treatments with MAL-PDT, MAL alone and LED alone. To evaluate the molecular changes in the epidermal and dermal matrix, primary cytokines such as interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), transforming growth factor-β1 (TGF-β1), matrix metalloproteinases (MMPs), procollagen type I and III were evaluated by reverse transcriptase polymerase chain reaction, Western blot analysis, and immunohistochemistry assays.ResultsElevation of primary cytokines and MMPs occurred at early points in time after one treatment with MAL-PDT based on the levels of mRNA and protein. On the other hand, procollagen type I protein increased later after MAL-PDT treatment.ConclusionsMAL-PDT activates more quantifiable alterations in the molecules associated with epidermal and dermal remodeling compared to treatment with MAL or LED alone. MAL-PDT significantly induced the epidermal and dermal matrix molecules required for photorejuvenation.