Effect And Mechanism Of Schwann Cells On Wound Healing In Diabetes Mice

Objective: A mice skin wound model was established,and the effect of Schwann cells on wound healing was analyzed by staining,immunohistochemistry and immunofluorescence;Aiming at the promoting repair effect of Schwann cells,the supernatant of Schwann cells was added in vitro to explore the possible mechanism of proliferation and migration of fibroblasts induced by Schwann cells.Methods: In this experiment,full-thickness dorsal skin defect wounds of C57/ B6 mice and DB/DB mice were established.Tissue samples were collected at different time points.Immunohistochemistry and immunofluorescence analysis were used to detect the expression of markers of Schwann cell dedifferentiation and proliferation,including myelin basic protein,p75,Ki67 and c-Jun.In addition,RSC96 cells and L929 cells were used for in vitro experiments.The characteristics of diabetes were simulated by using medium containing different glucose concentrations,normal glucose concentration(5.5m M)and high glucose concentration(50m M).To study the effect of high glucose on the dedifferentiation of Schwann cells and the paracrine effect of Schwann cells on the formation of myofibroblasts.And L929 cells were stimulated by the supernatant of RSC96 cells in different concentrations.Compared with L929 cells without stimulation,the migration and proliferation of L929 cells in the two groups were observed.Results: After full-thickness skin defect modeling,normal mice began to repair on the third day after operation,while diabetic mice began to repair on seventh days.Compared with the two groups,the healing process of normal mice was faster.Compared with diabetes mice,normal mice healed significantly between seventh days and fourteenth days.Similarly,the HE results showed that there was a significant difference in wound contraction between the two groups,and the normal mice were completely re-epithelialization on the fourteenth day,while the diabetes group was partially epithelialized.On the seventh day after operation,collagen and α-SMA content in wound tissue of diabetes mice were significantly lower than those of normal wounds.The density of neovascularization in normal mice was significantly higher than that of diabetes group on seventh days after operation.In the process of wound healing in normal mice,on the first day,Schwann cells showed that p75 began to be up-regulated,MBP was down regulated,cells dedifferentiated and migrated to the wound bed to promote healing.On the seventh day after diabetes,the p75 of Schwann cells began to increase and MBP was down regulated,but the dedifferentiated Schwann cells were limited to the nerve bundle and did not migrate out.Cell immunofluorescence experiments showed that in diabetes mice,the expression of p75 and Ki67 in Schwann cells was significantly reduced compared with that in normal mice,indicating that the viability of Schwann cells was impaired in diabetes.At the same time,the expression of dedifferentiated c-Jun in Schwann cells in diabetic wounds also decreased.In vitro experiments showed that under the high glucose environment,the scratch area contraction and the expression of p75,Ki67 and c-Jun in Schwann cells were lower than those in normal glucose concentration group.Compared with the high glucose concentration group,the normal glucose concentration group added RSC96 cells supernatant under the same conditions to stimulate L929 cells,showing the enhanced expression of Ki67 and α-SMA.Conclusion: Compared with normal mice,wound healing in diabetic mice was delayed after skin injury,and Schwann cells could not rapidly activate repair procedures.In addition,we found that Schwann cells from diabetic mice showed dysfunction in cell dedifferentiation,cell cycle re-entry and cell migration.In vitro,hyperglycemia impaired the dedifferentiation,cell cycle re-entry and cell migration of RSC96 cells,as well as their paracrine effects on myofibroblast formation,including TGF-β and TIMP1 secretion.Delayed healing of diabetic wounds is partly due to diminished Schwann cell repair responses and paracrine effects on myofibroblast formation.