GalT-KO Vascularized Thymic Transplantation for Xenograft Tolerance

可用供体同种异体移植物的短缺继续引发卫生保健危机，并提供了理由 继续异种移植研究我们正试图通过诱导 在非人灵长类动物中跨越不一致异种屏障的移植耐受性。我们的战略利用 来自GalT-KO猪的复合血管化胸腺-肾移植物。在最近的项目期间（后期 2004-2008），我们用“改良方案”显著降低了诱导期的并发症发生率， 它消除了类固醇和全身辐射。我们最重要的发现是（1）扩展平均 在修改后的方案下，维持生命的异种肾移植受者的生存期超过50天 与原始方案下的33天相比，免疫抑制方案;（2）体外可重现 供体特异性耐受的证据;和（3）CD 4/CD 8双阳性狒狒的证明 异种胸腺细胞在移植的猪胸腺移植物中，表明狒狒胸腺生成，否则没有 在大型动物异种移植模型中实现。据我们所知，这些结果代表了 维持生命的异种移植物的平均存活时间最长，也为耐受性提供了新的体外证据 在大型动物中。为了使这种方法更适用于临床，该提案将解决 耐受诱导、免疫抑制和异种肾移植问题的其余关键问题 在狒狒中的功能可能是由物种间的分子不相容性引起的。在目标1中，我们首先 证实异种猪血管化胸腺移植物诱导的免疫耐受， 使用我们最成功的方案维持免疫抑制我们还将努力实现 使用基于T细胞耗竭的方案治疗耐受性，以去除抗-CD 154 mAb和骨髓抑制 毒品在目标2中，我们将评估移植前后异种免疫的体外参数 血管化的胸腺组织我们将研究参与的基本细胞过程， 培养和保持宽容。在目标3中，我们将评估异种移植肾的原因 蛋白尿和制定预防策略。我们将探讨：1）抗非Gal抗体去除的效用 移植物植入前; 2）药理学辅助血管保护治疗显示临床上 有效治疗血管损伤/蛋白尿;和3）使用来自GalT-KO猪的肾， 其他转基因，包括hCD 39和血栓调节蛋白。一种临床上适用的 一项战略不仅将提供无限的捐赠器官供应，而且还将提供移植机会 在由于对同种异体人类供体的过敏而不能接受移植的患者中。

The shortage of available donor allografts continues to provoke a health care crisis and provides the rationale for continued xenotransplantation research. We are attempting to address these issues by inducing transplantation tolerance across discordant xenogeneic barriers in non-human primates. Our strategy utilizes composite vascularized thymic-renal grafts from GalT-KO swine. During the most recent project period (late 2004-2008), we markedly decreased the complication rate in the induction period with a "modified regimen," which eliminated steroids and whole body irradiation. Our most significant findings are (1) Extended average survival of life-supporting kidney xenograft recipients to greater than 50 days under the modified immunosuppression regimen as compared to 33 days under the original protocol; (2) Reproducible in vitro evidence for donor-specific tolerance; and (3) Demonstration of CD4/CD8 double positive baboon xenothymocytes in transplanted pig thymic grafts, indicating baboon thymopoiesis, which had otherwise not been achieved in a large animal xenotransplant model. To our knowledge, these results represent the longest average survival of life-supporting xenografts and also provide novel in vitro evidence for tolerance in large animals. In order to make this approach more clinically applicable, this proposal will address remaining crucial concerns of tolerance induction, immune suppression, and issues with renal xenograft function in baboons that may be caused by molecular incompatibilities across species. In Aim 1, we will first confirm immunologic tolerance induced by xenogeneic porcine vascularized thymic grafts and eliminate maintenance immunosuppression using our most successful regimen. We will also attempt to achieve tolerance with a T-cell depletion based regimen in order to remove anfi-CD154 mAb and myelosuppressive drugs. In Aim 2, we will assess in-vitro parameters of xenogeneic immunity before and after transplantation of vascularized thymic tissue. We will examine the fundamental cellular processes involved in the development and maintenance of tolerance. In Aim 3, we will evaluate the cause of xenograft kidney proteinuria and develop preventive strategies. We will explore: 1) the utility of anti-non-Gal antibody removal prior to graft implantation; 2) pharmacologic adjuvant vascular protective therapies shown to be clinically effective for treatment of vascular injury/proteinuria; and 3) the use of kidneys from GalT-KO pigs with additional transgenes, including hDAF, hCD39 and thrombomodulin. The success of a clinically applicable strategy would provide not only a limitless supply of donor organs but also opportunities for transplantation in patients unable to receive a transplant because of presensitization to allogeneic human donors.