GalT-KO Vascularized Thymic Transplantation for Xenograft Tolerance

可用的供体同种异体移植的短缺继续引发医疗危机，并提供了理由 用于继续异种移植研究。我们正试图通过诱导 非人类灵长类动物跨越不和谐异种屏障的移植耐受性。我们的战略利用 Galt-KO猪带血管胸腺-肾复合移植物。在最近的项目期间(延迟 2004-2008)，我们用“改良方案”明显降低了诱导期的并发症发生率。 它消除了类固醇和全身照射。我们最重要的发现是(1)扩展平均 支持生命的异种肾移植受者在改良方案下存活50天以上 免疫抑制方案与原方案下的33天相比；(2)体外可重复性 供者特异性耐受性的证据；以及(3)CD4/CD8双阳性狒狒的表现 移植的猪胸腺中的异种胸腺细胞，表明狒狒胸腺的生成，否则没有 已经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 支持生命的异种移植物的最长平均存活时间，也为耐受性提供了新的体外证据 在大型动物身上。为了使这一方法更适用于临床，本提案将解决 关于耐受性诱导、免疫抑制和异种肾移植问题的关键问题 这可能是由于不同物种间的分子不相容造成的。在目标1中，我们将首先 确认异种猪带血管胸腺移植物诱导免疫耐受并消除 使用我们最成功的治疗方案维持免疫抑制。我们还将努力实现 去除ANFI-CD154单抗和骨髓抑制的T细胞耗竭方案的耐受性 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。 带血管的胸腺组织。我们将研究涉及到的基本细胞过程 培养和维护耐受性。在目标3中，我们将评估异种肾移植的原因。 蛋白尿并制定预防策略。我们将探索：1)去除抗非半乳糖抗体的效用 移植前；2)临床证明的药物辅助血管保护治疗 有效治疗血管损伤/蛋白尿；以及3)使用来自Galt-KO猪的肾脏 其他转基因，包括hDAF、hCD39和血栓调节蛋白。一种临床应用的成功 这一战略不仅将提供无限的捐献器官供应，而且还将提供移植机会。 对于因对异基因人类捐献者预敏而无法接受移植的患者。

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.