| Objective:There is controversy about the mechanism how decreasing hyperglycemia and promoting islets regeneration after transplanted MSCs. Recent research suggest that MSCs can secrete stromal cell-derived factor 1(SDF-1). SDF-1 is associated with revascularization and tissue repairing, which might play an important role on revascularization and regeneration of damaged remnant islets of the recipients.To investigate the role of SDF-1/CXCR4 axis on recipients'remnant islets regeneration and neovascularization after the transplantation of allogeneic bone marrow mesenchymal stem cells(MSCs).Methods:MSCs were isolated from SD rat, cultured, Proliferated and purified in vitro under certain condition and then passaged 3 was transplanted in the diabetic rats.The diabetic rats was induced by peritoneal streptozotocin injection (65mg/kg).SD rats were anesthetized with intraperitoneal sodium pentobarbital (30mg/kg). Femurs and tibiae of rats were collected and adherent soft tissue was carefully removed. Bone marrow cells were flushed from the medullary cavities of femurs and tibiae and disaggregated into a single-cell suspension by sequential passage through a 25-gauge needle. MSCs were separated by centrifugation(1000rpm,10min). The cells were cultured in Dulbecco's modified Eagle's medium (DMEM/F12) containing10% fetal bovine serum (FBS). The diabetic rats induced by peritoneal injection of streptozotozin were randomly divided into group A (MSCs transplant group),group B(MSCs transplant+AMD group),group C(DM control group) ;Group D is control group.Each group contains 10 SD rats. The pancreas were removed and blood samples were retrieved from each group simultaneously at the 30th day after cells transplant.Detect the expression of CD31,PCNA and PDX-1 in each group of pancreas tissue by immunohistochemistry and observe the islets shape by Hematoxylin and Eosin(H-E) . Blood glucose and insulin in serum were detected by blood glucose monitor, radioimmunoscintigraphy and respectively SDF-1 in serum was detected by enzyme linked immunosorbent assay(ELISA).Results:Neovascularization were observed in the remnant islets of the recipient pancreatic tissue and CD31-positive cells(71.2±5.3)%,PCNA-positive cells(76.5±4.5)%,PDX-1-positive cells(69.8±6.7)% were observed in group A. Compared with group A, seldom-positive cells[CD31(7.4±2.1)%, PCNA(5.5±3.7)% and PDX-1(8.8±2.9)%] and rarely neovascularization were observed in group B and group C(p<0.05). Blood glucose level in serum of group A was lower than that of group B and group C,but insulin level in serum of group A was significantly higher than that of group B and group C(p<0.05). There are no significant difference between group A and group B in SDF-1 level in serum(p>0.05),but both were higher than that of group C(p<0.05).Conclusion:Obviously,MSCs promote recipient neovascularization surrounding the islets,which enhanced the proliferation and regeneration remnant of islet cells.AMD 3100 has the function of interrupting SDF-1/CXCR4 axis which inhibits the effect of MSCs on promoting islets regeneration.Therefore we concluded that SDF-1/CXCR4 axis play an important role in vascularization and islets regeneration. |
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