Abstract: Objective To determine the expression changes of skin regeneration-related key genes under mechanical stretch stimulation in rats and to screen key genes. Methods Skin expansion model was established and skin samples were harvested: the unexpanded control group (con), water-injected 60 mL group (exp60), water-injected 120 mL group (exp120) and water-injected 180 mL group (exp180). Immunohistochemical staining was implemented in the sliced the sample, stain-ing proliferation marker Ki67. According to that, the trend curve of Ki67 positive rate of samples was drawn. Gene Chip was also undertaken to reveal the gene expression changes during expansion process. T test and fold change of differential ex-pression were applied to screen key genes. Then PCR was used to confirm the relationship between the expression of the key gene and the proliferation of skin. Results Immunofluorescence staining showed that, the expression of the proliferation marker Ki67 descending order is con, exp180, exp60, exp120. This study screened 11 skin regeneration-related key genes of rats under different mechanical stretch stimulation: Myh1, Myh2, Myh3, Myh4, Car6, Pi15, Apt12a, Mt1a, Cthrc1, Rsad2, IGF-BP5. Compared to the expression of control group, IGF-BP5 was a down-regulated gene. PCR showed that the expres-sion of IGF-BP5 descending order was: exp120, exp60, exp180, con. Conclusion Under mechanical stretch stimulation, with the increasing time of expansion and amount of water injected, skin regeneration of rats shows accelerated proliferation at early stage, active proliferation in the mid-term and tendency to slow down the proliferation in the later period; IGF-BP5 may be a key regeneration-related gene of rats under mechanical stretch stimulation.

Key words: Skin expansion, Mechanical stretch, Skin regeneration, Gene chip