| Background: Type1diabetes mellitus is an autoimmune disorder inwhich the immune system destroys the insulin producing. In recentdecades, the incidence of type1diabetes is increasing year by year.Exogenous insulin can regulate blood glucose in patients with type1diabetes, but using insulin excessively or adjusting blood sugar toofrequently may cause severe hypoglycemia. Plasma glucose level inpatient with excessive fluctuations can also lead to diabetes-relatedcomplications. Islet transplantation was a treatment with small surgicalrisk, high specificity, physiological advantages and a treatment for thecause of type1diabetes mellitus. Islet transplantation for the treatmentof type1diabetes is an ideal treatment and is expected to completelycure type1diabetes. But islet graft was a low long-term survival rate andthe5-year survival rate was about10%.Some studies have found thatearly islet transplantation directly affect survival rate of the islets. Theislets whether need culture before islet transplantation is stillcontroversial. Our experiment is to compare the function andrevascularization of islets in mice with diabetes after the fresh or cultured islets transplantation and also to provide a theoretical basis for theimprovement of clinic islet transplantation.Objective: To observe the influence of function andrevascularization of islets in mice with diabetes after the fresh or culturedislets transplantation.Methods: Diabetic C57BC/6mouse models were induced Byintraperitoneal injection of streptozotocin (STZ). The diabetic C57BC/6mice were divided into three groups, named group A,B and C respectively（n=10）. Pancreaticisletsofdonorwere obtained from C57BC/6mice bydigestion of collagenase P solution and Ficoll400density gradientcentrifugation. Through Dithizone (DTZ) stained, morphology and thenumber of the islet was observed under the microscope.And alsodetected the secretory function and activity of pancreatic islet.Syngenetic islets transplantation under renal capsule were performed,themice in group A received250IEQ（islet cell with diameter>150um）freshislets;the mice in group B received250IEQ islets with one day cultured;the mice in group C(n=10) received250IEQ islets with three dayscultured.The blood glucose in the three groups of diabetic mice after graftwere monitored,HE and immunohistochemical staining was used todetect the expression of insulin and CD31under the capsule of the kidneyafter transplantation of14days. The microvascular density（MVD）wasalso calculated. Results: The successful rate of diabetic model was83%and everyC57BL/6mouse could obtain200±10IEQ islets and the purity was80±5%. The insulin secretion were25.34±2.12mU/L and76.32±2.25mU/L in low-sugar and high glucose respectively after five days cultured.The difference between them was significant. The function of the isletswas in good condition. The blood glucose can decrease to less than11mmol/L after equivalent islets transplantation of the diabetic mice inthe three groups. The blood glucose of mice in Group A was less than11mmol/L and maintained more than14days, but that in group B and Ccontinued to rise after three days graft and both were more than11mmol/Lafter14days. Differences among the three groups were statisticallysignificant (p<0.05).The blood glucose change in group A compared withgroup B or group C,the difference was significant(p<0.05，p<0.05).Butthe difference of blood glucose between group B and group C was notsignificant(p>0.05). There was a group of Islets under the capsule ofkidney of the mouse observed by the HE staining. Compared with groupB and C, the islets in group A were more regular and the cytoplasm andnucleus were separated more significantly and in a better condition.Immunohistochemistry showed a large amount of Insulin positive cells incell masses of the group A, whereas insulin positive cells were seldomseen in the group B and group C. Immunohistochemical staining showedthat a large number of cytoplasmic were under the capsule of the kidney in group A, which were positively stained by CD31,while there were a fewpositive cells stained by CD31in group B and C. The differences ofmicrovascular density(MVD) among the three groups were statisticallysignificant (p <0.05).MVD in group A was markedly higher than that ingroup B or C,the difference was significant(p<0.05，p<0.05).There wasno significant difference between group B and C（p>0.05）.Conclusion: Compared with cultured islets graft, fresh islets graftcan improve the revascularization and survival of islet cell clusters afterislet graft in mice. |
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