Revascularization of Islets to Treat Type I Diabetes

描述(申请人提供)：I型糖尿病的一个潜在的长期解决方案是朗格汉斯胰岛移植。在最近的临床试验中取得了显着的成功，大量的人胰岛用于移植，并结合高度发展的免疫抑制治疗方案。结果表明，对少数患者的治疗是多么有效，但捐赠者提供的人体胰岛数量远远不足以满足人类人口的需求。胰岛的最佳非人类捐赠者是猪。要使胰岛移植达到最佳状态，很可能必须通过增加移植胰岛的血液供应来改善其存活率。血管内皮细胞(EC)已被用来在三维胶原凝胶中形成新生微血管床。我们已经证明，过表达的Bcl-2可以促进血管重建，保护人的内皮细胞免受细胞毒性淋巴细胞的破坏。将开发条件，在这些胶原蛋白凝胶中创造血运重建的猪胰岛或“微器官”，以促进胰岛在体内的存活和功能。人内皮细胞和胰岛将结合在一起，并表征其结构/功能特性。我们将通过随时间推移进行葡萄糖耐量测试和胰岛素分泌来测试这些移植物的功能。我们将确定人微血管与猪胰岛的最佳组合。将进行原则性实验证明，这些微器官可以治疗化学诱导的糖尿病。临床上可能希望使用来自胰岛微器官受体的同基因EC来形成微血管。因此，我们将尝试从CD34+祖细胞中培养出足够的EC，以形成微器官。最后，我们将通过在免疫缺陷小鼠模型中重建人类免疫系统来评估微器官移植的免疫原性。这些研究可能导致治疗I型糖尿病的新方法，既提高胰岛移植的效率，又解决供体胰岛严重缺乏的问题。

DESCRIPTION (provided by applicant): A potential long term solution to type I diabetes is the transplantation of the islets of Langerhans. Notable success in recent clinical trials has been achieved with large numbers of human islets used for transplantation combined with highly developed immunosuppressive treatment protocols. The results show how effective treatment can be for a few patients but there are nowhere near adequate numbers of human islets available from donors to meet the needs of the human population. The best candidate non-human donor for islets is the pig. For islet transplantation to be optimal it is likely that improvements in their survival must be made by increasing the blood supply to the transplanted islet. Endothelial cells (EC) have been utilized to form a de novo microvascular bed in three-dimensional collagen gels. We have shown that overexpression of Bcl-2 enhances revascularization and protects human EC from destruction by cytotoxic lymphocytes. Conditions will be developed to create revascularized porcine islets or "microorgans" in these collagen gels to promote islet survival and function in vivo. Human endothelial cells and islets will be combined and their structure/function properties characterized. We will test the functionality of these grafts by performing glucose tolerance tests and insulin secretion over time. We will determine the optimum combination of human microvessels with pig islets. Proof of principle experiments will be done to show that these microorgans can cure chemically induced diabetes. It might be clinically desirable to utilize syngeneic EC from an islet microorgan recipient for the formation of microvessels. Therefore we will attempt to culture sufficient EC derived from CD34+ progenitor cells to form the microorgans. Finally, we will evaluate the immunogenicity of the microorgan grafts by reconstitution of the human immune system in immunodeficient mouse models. These studies could lead to new methodologies to treat type I diabetes enhancing both the efficiency of islet transplantation and address the severe lack of donor islets.