Abstract
OBJECTIVE: To determine the expression level of Sonic hedgehog (Shh) in the passage of hair follicle stem cells (HFSCs), analyze the effect of Shh overexpression on the proliferation activity of HFSCs, and explore the survival of HFSCs after Shh overexpression and its effect on hair follicle regeneration. METHODS: Hair follicles from the normal area (H1 group) and alopecia area (H2 group) of the scalp donated by 20 female alopecia patients aged 40-50 years old were taken, and the middle part of the hair follicle was cut under the microscope to culture, and the primary HFSCs were obtained and passaged; the positive markers (CD29, CD71) and negative marker (CD34) on the surface of the fourth generation HFSCs were identified by flow cytometry. The two groups of HFSCs were transfected with Shh-overexpressed lentivirus. Flow cytometry and cell counting kit 8 assay were used to detect the cell cycle changes and cell proliferation of HFSCs before and after transfection, respectively. Then the HFSCs transfected with Shh lentivirus were transplanted subcutaneously into the back of nude mice as the experimental group, and the same amount of saline was injected as the control group. At 5 weeks after cell transplantation, the expression of Shh protein in the back skin tissue of nude mice was detected by Western blot. HE staining and immunofluorescence staining were used to compare the number of hair follicles and the survival of HFSCs between groups. RESULTS: The isolated and cultured cells were fusiform and firmly attached to the wall; flow cytometry showed that CD29 and CD71 were highly expressed on the surface of the cells, while CD34 was lowly expressed, suggesting that the cultured cells were HFSCs. The results of real-time fluorescence quantitative PCR and Western blot showed that the expression levels of Shh protein and gene in the 4th, 7th, and 10th passages of cells in H1 and H2 groups decreased gradually with the prolongation of culture time in vitro. After overexpression of Shh, the proliferation activity of HFSCs in the two groups was significantly higher than that in the blank group (not transfected with lentivirus) and the negative control group (transfected with negative control lentivirus), and the proliferation activity of HFSCs in H1 group was significantly higher than that in H2 group before and after transfection, showing significant differences ( P<0.05). At 5 weeks after cell transplantation, Shh protein was stably expressed in the dorsal skin of each experimental group; the number of hair follicles and the expression levels of HFSCs markers (CD71, cytokeratin 15) in each experimental group were significantly higher than those in the control group, and the number of hair follicles and the expression levels of HFSCs markers in H1 group were significantly higher than those in H2 group, and the differences were significant ( P<0.05). CONCLUSION: Lentivirus-mediated Shh can be successfully transfected into HFSCs, the proliferation activity of HFSCs significantly increase after overexpression of Shh, which can secrete and express Shh continuously and stably, and promote hair follicle regeneration by combining the advantages of stem cells and Shh.