Thromboregulatory Barriers to Xenotransplantation

异种移植只有在异种移植物丢失和排斥机制被证实后， 更好地理解。去除显性基因的近交小型GalT-KO猪的培育 异种抗原是一个重大进展。然而，在产生混合异种中仍然存在问题， 嵌合体，并获得对异种细胞和血管化异种移植物的耐受性。 猪骨髓源细胞的炎症反应与器官移植物的血管系统有关 异常免疫反应，以及促凝血剂激活和异种移植物的发展 微血管损伤血栓形成过程和进行性异种移植物微血管病出现 由于免疫反应失调和已经证实的内在分子 不一致物种之间血栓调节的不相容性。我们在以下方面取得了重大进展 定义与CD39相关功能不相容性相关的消耗性凝血病的机制 和血栓调节蛋白，并通过确定新的血管损伤标志物， 体液排斥我们最近发现CD 39由内皮细胞和T细胞表达 调节细胞因此，由这种外核苷酸酶产生的腺苷阻断血小板活化， 凝血并且还充当免疫抑制介质。 我们的新研究将在这些成功和见解的基础上实现以下具体目标：#1： 研究细胞免疫机制和腺苷的产生如何受T细胞表达的CD39的调节 细胞影响异种耐受机制（项目3中开发的模型）;以及#2：证明 人CD39和血栓调节蛋白在GalT-KO猪中转基因上调的治疗潜力 胸腺肾异种移植和耐受模型（项目1和2）。 这些策略将包括最佳的免疫抑制干预与方案，试图诱导 耐受性和改善狒狒血管炎症。此应用程序的总体目标是 有效管理目前与GalT-KO相关的免疫反应、移植血管损伤和血栓形成 猪-狒狒胸腺肾异种移植，从而提供临床相关的存活时间。

Xenotransplantation will only become clinically feasible once mechanisms of xenograft loss and rejection are better understood. The development of inbred miniature GalT-KO swine with removal of the dominant xeno-antigen has been a major advance. However, problems still persist in generating mixed xenogeneic chimerism in baboons and obtaining tolerance to xenogeneic cells and vascularized xenografts. Inflammatory reactions to porcine bone marrow-derived cells and the vasculature of organ grafts are linked to aberrant immune responses, together with procoagulant activation and the development of xenograft microvascular injury. Thrombotic processes and the progressive xenograft microangiopathy appear exacerbated by dysfunctional immune reactions and already documented intrinsic molecular incompatibilities in thromboregulation between discordant species. We have made significant progress in defining mechanisms of consumptive coagulopathy linked to associated functional incompatibilities of CD39 and thrombomodulin across species, and by determining novel vascular markers of injury associated with humoral rejection. We have recently shown that CD39 is expressed by the endothelium and also by T regulatory cells. Hence, adenosine generated by this ectonucleotidase blocks platelet activation impeding coagulation and also serves as an immune suppressive mediator. Our new studies will build on these successes and insights to address the following Specific Aims: #1: Study how cellular immune mechanisms and adenosine production by CD39 expressed by T regulatory cells impact xenogeneic tolerance mechanisms (with models developed in Project 3); and #2: Demonstrate therapeutic potential of transgenic upregulation of human CD39 and thrombomodulin in GalT-KO swine in thymokidney xenotransplant and tolerance models (in Projects 1 and 2). These strategies will include optimal immunosuppressive interventions with protocols to attempt induction of tolerance and ameliorate vascular inflammation in baboons. The overall goals of this application will be to effectively manage immune reactions, graft vascular Injury and thrombosis, currently associated with GalT-KO pig-to-baboon thymokidney xenotransplantation, and thereby provide clinically relevant survival times.