5-Aminolevulinic acid-based photodynamic therapy preconditioning relieves the apoptosis of human skin fibroblasts induced by middle-wave ultraviolet

Objective To observe the effects of 5-aminolevulinic photodynamic therapy (ALA-PDT) preconditioning on the proliferation and apoptosis of human skin fibroblasts in vitro after middle-wave ultraviolet (UVB) radiation. Methods Human skin fibroblasts were pretreated with a low-dose of ALA-PDT, followed by acute UVB radiation at 60 mJ/cm². Then, cell morphology was observed under an inverted microscope. The cell viability was detected by CCK-8 assay. The cell apoptotic rate was examined by Annexin V (Annexin V)/propidium iodide (PI) double staining. In addition, the cell mitochondrial membrane potential changes were detected by JC-1 kit. The amounts of apoptosis-related proteins such as cysteine-requiring aspartate protease 3 (caspase3), B-cell lymphoma-2 (Bcl-2)and Bcl-2-associated X (Bax) were detected by Western blot. Results Compared with the UVB group, less cell debris and intercellular spaces were observed in the ALA-PDT-UVB group under the inverted microscope. CCK-8 results indicated more active cell proliferation activities in the ALA-PDT-UVB group. The AV/PI double staining and the mitochondrial membrane potential results showed less apoptosis in the ALA-PDT-UVB group. Furthermore, increased levels of caspase-3 and Bcl-2 and a decreased level of Bax were found in the ALA-PDT-UVB group. Conclusions A low-dose of ALA-PDT preconditioning can significantly reverse cell apoptosis caused by acute UVB radiation, and influence the expression of apoptosis-related proteins such as caspase-3, Bax, and Bcl-2, so as to exert photoprotective effects.