Thromboregulatory strategies to prolong xenograft survival.

描述（由申请人提供）：一旦物种之间的分子屏障和移植物丢失或排斥的机制得到更好的理解，异种移植可能在临床上是可行的。异种移植物的存活也必须在不损害受体的情况下达到可能遇到全身毒性的程度。在这方面，猪的基因工程，与异种移植修饰，以提供更大的兼容性，已成为最近的兴趣。猪骨髓（BM）来源细胞、输注胰岛和器官移植血管的血栓和炎症反应与建立混合不协调嵌合的困难、胰岛相关的促凝剂损伤和异种移植物微血管病变的发展有关。这些反应可能与对异种组织的体液免疫反应有关。然而，进行性异种移植物血管损伤和梗死的血栓形成过程可能会进一步加剧，因为在不一致物种之间的血液凝固调节中存在固有的分子不相容。这方面的一个例子是，天然猪抗凝血剂（如血栓调节素）无法与人/灵长类动物凝血因子（如凝血酶和c蛋白）相互作用。GalT-KO猪的开发和随后的显性异种抗原的去除是异种移植研究的一个重大进展。然而，在狒狒中，通过产生混合异种嵌合来诱导耐受性的问题仍然存在，无论是通过血管化胸腺组织还是bm衍生细胞方法。GalT-KO胰岛尚未测试，但目前GalT-KO肾脏和心脏异种移植有限的生存时间和相关的血管损伤模式仍然阻碍了临床应用。本应用的目的是有效地处理与GalT-KO猪到狒狒肾移植相关的移植物血栓和血管后遗症以及在胰岛异种移植中看到的并发症。我们将评估转基因方法来过度表达CD39，这是一种关键的凝血调节蛋白和/或凝血调节蛋白。转基因猪血管化肾移植物和过度表达这些人类因子的胰岛将被移植到狒狒体内。我们的策略将包括最佳的免疫抑制干预方案，以尝试诱导耐受性。如果能够开发和应用新的临床相关抗血栓治疗方法，这些研究将被认为是成功的。

DESCRIPTION (provided by applicant): Xenotransplantation may be clinically feasible once the molecular barriers between species and mechanisms of graft loss or rejection are better understood. Xenograft survival would have to be also achieved without compromising the recipient to the extent that systemic toxicity would be encountered. In this regard, genetic engineering of swine, with xenograft modification to provide greater compatibility, has been of recent interest. Thrombotic and inflammatory reactions to porcine bone marrow (BM)-derived cells, infused pancreatic islets and the vasculature of organ grafts are linked to the difficulties in establishing mixed discordant chimerism, pancreatic islet-associated procoagulant injury and the development of xenograft microangiopathy. These responses are likely associated with humoral immune reactions to xenogeneic tissues. However, thrombotic processes with progressive xenograft vascular injury and infarction may be further exacerbated by documented intrinsic molecular incompatibilities in regulation of blood clotting between discordant species. An example of this would be the failure of natural porcine anticoagulants, such as thrombomodulin, to interact with human/primate coagulation factors, such as thrombin and Protein C. The development of the GalT-KO pig and consequent removal of the dominant xeno-antigen have been a major advance in xenotransplantation research. However, problems still persist in inducing tolerance by generating mixed xenogeneic chimerism, either by vascularized thymic tissues or the BM-derived cell approach in baboons. GalT-KO islets have not yet been tested but the current GalT-KO renal and cardiac xenograft limited survival times and associated vascular injury patterns still preclude clinical application. The goals of this application are to effectively manage graft thrombotic and vascular sequelae associated with GalT-KO pig-to-baboon renal grafting and those complications seen in islet xenotransplantation. We will evaluate transgenic approaches to over-express CD39, a key thromboregulatory protein and/or thrombomodulin in pigs. Transgenic porcine vascularized renal grafts and pancreatic islets over-expressing these human factors will be transplanted into baboons. Our strategies will include optimal immunosuppressive interventions with protocols to attempt induction of tolerance. These studies will be judged successful if novel, clinically relevant antithrombotic therapies can be then developed and applied.