5-Aminolevulinic Acid-Based Photodynamic Therapy Pretreatment Mitigates Ultraviolet A-Induced Oxidative Photodamage

AIM: To determine whether 5-aminolevulinic acid-based photodynamic therapy (ALA-PDT) is effective in combating ultraviolet A- (UVA-) induced oxidative photodamage of hairless mice skin in vivo and human epidermal keratinocytes in vitro. METHODS: In in vitro experiments, the human keratinocyte cell line (HaCaT cells) was divided into two groups: the experimental group was treated with ALA-PDT and the control group was left untreated. Then, the experimental group and the control group of cells were exposed to 10 J/m(2) of UVA radiation. ROS, O(2)(−) species, and MMP were determined by fluorescence microscopy; p53, OGG1, and XPC were determined by Western blot analysis; apoptosis was determined by flow cytometry; and 8-oxo-dG was determined by immunofluorescence. Moreover, HaCaT cells were also treated with ALA-PDT. Then, SOD1 and SOD2 were examined by Western blot analysis. In in vivo experiments, the dorsal skin of hairless mice was treated with ALA-PDT or saline-PDT, and then, they were exposed to 20 J/m(2) UVA light. The compound 8-oxo-dG was detected by immunofluorescence. CONCLUSION: In human epidermal keratinocytes and hairless mice skin, UVA-induced oxidative damage can be prevented effectively with ALA-PDT pretreatment.