The Expression Of GIPR In Vascular Endothelial Cells In Transplanted Islets

Objective : To investigate the expression of GIPR in vascular endothelial cells in transplanted islets .Method:Pancreas of SD rat were digested by collagenase V after the common bile ductal injection of collagenase V. Islets were purified by Ficoll discontinuous density gradient-centrifugation. Trypan blue were used to assess the survival rate of the islets. Then the high-quality islets were immediately transplanted intraportally into the liver of recipient SD rats with streptozotocin-induced diabetes.The recipient rats were randomly devided into 4 groups based on time points that recipients be killed : group A(7 days),group B(14 days),group C (40 days)and group D(60 days). The immunosuppressive tacrolimus(FK506) and mycophenolate mofetil(MMF) were administered to recipients by intragastric administration posttransplantation. Concentrations of blood glucose in recipient were determined with monitor .The groups were respectively killed by cervical dislocation at time points 7 days,14 days,40 days and 60 days, then islet grafts and the expression of GIPR in vascular endothelial cells were observed morphologically. Results: By digested with collagenase, the yield of islets of SD rats was 662.33±148.05 islets per pancreas ,the purity was 85% and survival rate was beyond 92%. Serious immunological rejection was not observed. The level of blood glucose concentrations became normal in 3-5 days posttransplantation. Most of the islets existed in the branch of portal vein and some of signal islet cells existed in hepatic sinusoid. GIPR were expressed in parts of the vascular endothelial cells in islet grafts in each group. The GIPR-positive vascular densities of the four groups were respectively 0.0316±0.0121,0.0531±0.0166,0.0964±0.0391,0.1013±0.0433 capillaries/cm2。Conclusion:High-quality islets could be obtained by digestion with collagenase and purification with discontinuous Ficoll solution . FK506+MMF could provide effective immunosuppression and transplanted islet survivalled well for long term .GIPR were found to be expressed in parts of the microvascular endothelial cells, which means GIPR-positive endothelial cells took part in microvascular reconstruction in islet grafts. The neogenetic islet endothelial cells might acquired some common characteristic with that of liver, and GIPR might affect the function of islets and angiogenesis.