Thromboregulatory strategies to prolong xenograft survival.

描述(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。异种移植的存活率也必须在不损害受体的情况下实现，否则会遇到全身毒性。在这方面，猪的基因工程，通过异种移植的修饰来提供更好的兼容性，最近引起了人们的兴趣。对猪骨髓(BM)来源的细胞、输注的胰岛和器官移植物的血管的血栓和炎症反应与建立混合不协调嵌合体的困难、胰岛相关性促凝血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，随着异种移植血管损伤和梗塞的进行性发展，血栓形成过程可能会进一步加剧，因为已有文献证明，在调节不协调物种之间的血液凝结方面存在内在的分子不相容。一个例子是天然的猪抗凝剂，如血栓调节蛋白，不能与人/灵长类凝血因子，如凝血酶和蛋白C相互作用。GALT-KO猪的发展和随之而来的主要异种抗原的去除是异种移植研究的主要进展。然而，通过产生混合异种嵌合体来诱导耐受性的问题仍然存在，无论是通过血管胸腺组织还是通过在狒狒身上使用骨髓来源细胞的方法。Galt-KO胰岛尚未进行测试，但目前Galt-KO异种心脏和肾移植的存活时间有限，相关的血管损伤模式仍然阻碍了临床应用。这项应用的目标是有效地处理与Galt-KO猪到狒狒肾移植相关的移植物血栓和血管后遗症，以及在异种胰岛移植中看到的那些并发症。我们将评估在猪中过表达CD39的转基因方法，CD39是一种关键的血栓调节蛋白和/或血栓调节蛋白。过度表达这些人类因子的转基因猪带血管肾移植和胰岛将被移植到狒狒体内。我们的策略将包括最佳免疫抑制干预方案，以尝试诱导耐受。如果能够开发和应用新的、临床相关的抗血栓疗法，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.