Revascularization of Islets to Treat Type I Diabetes

描述（由申请人提供）：I型糖尿病的潜在长期解决方案是胰岛移植。在最近的临床试验中，大量用于移植的人类胰岛与高度发达的免疫抑制治疗方案相结合，取得了显著的成功。研究结果显示了对少数患者的有效治疗，但从捐赠者那里获得的人类胰岛数量远远不能满足人类的需求。最好的非人类胰岛捐赠者是猪。对于胰岛移植是最佳的，可能必须通过增加对移植胰岛的血液供应来改善其存活率。内皮细胞（EC）已被用于在三维胶原凝胶中形成新生微血管床。我们已经表明，Bcl-2的过表达增强血管再生和保护人类EC破坏细胞毒性淋巴细胞。将开发条件以在这些胶原凝胶中产生血管化的猪胰岛或“微器官”，以促进胰岛在体内的存活和功能。将人内皮细胞和胰岛组合，并表征其结构/功能特性。我们将通过进行葡萄糖耐量试验和胰岛素分泌随时间的变化来测试这些移植物的功能。我们将确定人类微血管与猪胰岛的最佳组合。将进行原理实验证明，以表明这些微器官可以治愈化学诱导的糖尿病。临床上可能需要利用来自胰岛微器官受体的同基因EC用于微血管的形成。因此，我们将尝试培养足够的EC来源于CD 34+祖细胞，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物的免疫原性。这些研究可能导致治疗I型糖尿病的新方法，提高胰岛移植的效率并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.