Laser irradiation with 648 nm light stimulates autophagic human skin keratinocytes : peer reviewed original article

Background Laser phototherapy promotes cell viability, cell proliferation and migration. This study aimed to determine if laser irradiation could stimulate cellular responses of stressed cells to promote cell survival. Materials and Methods Human keratinocytes were treated with 200 µM hydrogen peroxide (H 2 O 2 ) or 0.4 µg/ml oligomycin to induce autophagy and 5% absolute ethanol (EtOH) or 12 µM tertbutylhydroperoxide (tBHP) to induce apoptosis (control). Cells were irradiated using 1.5 J/cm 2 with 648 nm and cellular responses were measured after 1 h or after 24 h and 96 h at 37°C. Results Irradiated cells treated with 200 µM H 2 O 2 showed an increase in cell proliferation and decrease in intracellular calcium. Irradiated oligomycin treated cells showed a significant increase in intracellular calcium. Irradiated apoptotic (control) cells showed a decrease in ATP viability, an increase in cytotoxicity, decrease in intracellular Ca 2+ and decrease in cell proliferation. Conclusion Irradiated 200 µM H 2 O 2 cells reverted to metabolically active, viable cells capable of proliferating within 96 h of laser irradiation. Changes in intracellular calcium following laser irradiation appear to influence cell survival and proliferation of stressed keratinocytes.