Abstract: Objective To investigate the effect of 308 nm monochromatic excimer light on the apoptosis,cell cycle and stem cell factor(SCF)expression of human keratinocytes.Methods MTT was used to determine the optimal dose of the excimer light on the keratinocytes,and flow cytometry to examine the apoptosis and cell cycle of keratinocytes.The mRNA and protein expression of SCF was detected by RT-PCR and Western blot,respectively.Results The apoptosis rate of keratinocytes was significantly increased at 24 h and 48 h after the radiation with 308 nm monochromatic excimer light of 400 mJ/cm²(both P<0.05).The cell count at S stage was elevated 48 h after the radiation,but no statistical difference was found for the elevation.Both the mRNA and protein expression of SCF increased after the radiation, and peaked at 12 h.The excimer light up-regulated the protein expression,but not mRNA expression of SCF,in a dose dependant manner.Conclusions The 308 nm excimer light could induce the apoptosis,and promote the expression of SCF mRNA and protein expression of keratinocytes,which might be a therapeutic mechanism of 308 nm excimer light in vitiligo.

Key words: Keratinocytes, Apoptosis, Stem cell factor, Excimer light