Development of effective methods of islet transplantation for severe diabetes mellitus.

1. 从Lewis大鼠身上分离朗格汉斯胰岛，通过门静脉或肾包膜下间隙（SNCS）分别移植到皮下组织（SCT）、肝脏中。移植后4周，胰岛素染色显示肝脏和SNCS处有存活的胰岛，但SCT.2处没有。胰蛋白酶处理后，对正常大鼠胰腺、分离后的朗格汉斯胰岛和肝脏或SNCS移植胰岛进行血管内皮生长因子（VEGF）免疫染色。正常胰腺和分离后的胰岛呈阳性染色，而移植（Tx）部位的胰岛往往呈vegf阴性。另一方面，即使在Tx部位的胰岛，微波处理后的VEGF染色也显示出阳性结果，这表明在Tx后VEGF仍然存在。血管标志物，因子viii相关抗原（vWF）和新生血管特异性标志物，血小板内皮细胞粘附分子-1 （PECAM-1/CD-31）也进行了类似的免疫染色。PECAM-1在正常胰岛中未被染色，但在胰岛的Tx部位染色呈阳性，而vWF在正常胰岛和移植胰岛中染色。采用胰岛移植链脲佐菌素（STZ）治疗糖尿病大鼠，观察了抗新生血管剂TNP-470的作用。给药TNP-470在饲喂状态和口服葡萄糖耐量试验中均未改变血糖水平。然而，在没有TNP-470治疗的正常大鼠和胰岛移植的stz大鼠中观察到，它消除了口服葡萄糖刺激的血浆胰岛素升高。组织学检查显示血管样管状结构，缺乏pecam -1阳性内皮层。提示移植胰岛可诱导新生血管形成，促进新生血管形成的治疗可改善移植胰岛的功能。

1. Islets of Langerhans were isolated from Lewis rats and transplanted to the same descent rats at either subcutaneous tissue (SCT), liver via the portal vein or subnephrocapsular space (SNCS). Up to 4 weeks after transplantation, insulin staining showed viable islets at the liver and SNCS but not at SCT.2. Normal rat pancreas, islets of Langerhans immediately after isolation, and transplanted islets either at the liver or SNCS were immunostained for vascular endothelial growth factor (VEGF) after trypsin treatment. Islets in the normal pancreas and immediately after isolation were positively stained but those at transplantation (Tx) sites tended to be VEGF-negative. On the other hand, VEGF-staining after microwave treatment showed positive results even in the islets at Tx sites, suggesting that VEGF still exists after Tx. A marker for blood vassels, factor VIII-related antigen (vWF), and specific marker for neogeneic vessels, platelet endothelial cell adhesion molecule-1 (PECAM-1/CD-31) were similarly immunostained. PECAM-1 was not stained in the islets of normal pancreas but became positively stained in those at Tx sites, whereas vWF was stained in normal and transplanted islets.3. Effects of an anti-neovascularization agent, TNP-470, were examined in islet-transplanted streptozotocin (STZ)-diabetic rats. Administered of TNP-470 did not altered blood glucose levels either at fed state or during oral glucose tolerance test. However, it abolished plasma insulin increase in response to oral glucose challenge, which was observed in normal rats and islet-transplanted STZ-rats without TNP-470 treatment. Histological examination revealed vessel-like tubular structures, which lack PECAM-1-positive endothelial layer.These results suggest that neovascularization can be evoked from transplanted islets and that neovascularization-promoting treatment may improve the function of transplanted islets.