Studies in pig-to-primate cardiac xenotransplantation

描述(由申请人提供)： 这项应用的目标是在猪到灵长类动物模型中实现维持生命的异种心脏移植(CXTx)的中位存活90天，使用基因工程供体、临床免疫抑制(IS)和导致CXTx临床前研究的迟发性异种移植排斥(DXR)的诊断和治疗方法。非半乳糖抗体介导的DXR(NGDXR)限制了异种移植物的存活时间。随着原位移植(OCXTx)结果的改善，已发现高达50%的病例早期异种移植功能受损。我们称之为围手术期异种心脏移植功能障碍(PCXD)。对于CXTx未来的潜在临床应用，了解NGDXR和PCXD的作用机制并改善其预后是至关重要的。所有针对特定目标(SA)1-3的移植将使用转基因CD55的供者，但GGTA-1糖基转移酶基因(GTKO：CD55+)失活。在SA 1中，为了更好地了解PCXD，将使用血浆置换法去除预先形成的非半乳糖抗体(PNGA)，并在OCXTx之前给予蛋白酶体抑制剂Bortezomib来删除浆细胞。这一疗法还将与卡波利特心脏保存相结合，以减轻术前损伤。PNGA耗竭和cariporide治疗对PCXD的影响将通过超声心动图(ECHO)的心功能测量、心脏损伤的生化标记物、受体抗体和血浆细胞水平来评估，并将与临时活检和移植心脏的心脏基因表达相关。在SA 2中，为了预防DXR的最佳治疗是基于对B细胞和T细胞的诱导治疗，将使用三联药物IS和Bortezomib来控制存活SA 1的OCXTx受体的NGA。我们将通过对GTKO PAECs的抗体反应和我们鉴定的新的个体化非半乳糖和蛋白质靶抗原的分析，进一步研究NGDXR的机制(S)。心脏基因表达的改变将与DXR相关。在SA 3中，我们使用了支持生命的胸腔内异位心脏移植变种CXTx，这是目前临床上使用的一种心脏移植变种，作为CXTx初步临床应用的潜在技术，它将独特地允许a)通过ECHO观察PCXD的恢复，以及b)开发诊断和治疗DXR的方法，而不会失去受者，因为在这些异种移植功能障碍期间，天然心脏支持循环。为此，将使用血浆置换和Bortezomib治疗DXR。这项申请的目标是实现循环承载CXTx的3个月中位生存期，如果成功，将为这一赠款期间的临床前研究奠定基础，以支持CXTx的临床应用。 相关性：异种移植的成功为缓解移植供体器官和细胞的长期和日益短缺提供了一种潜在的临床解决方案。我们之前超过12年的研究已经实现了异位心脏移植最长的中位存活时间和维持生命的原位心脏移植最长的存活时间。该提案的具体目标的实现将使异种心脏移植进入临床应用的门槛。

DESCRIPTION (provided by applicant): The objective of this application is to achieve 90-day median survival of life-supporting cardiac xenotransplantation (CXTx) in the pig-to-primate model using genetically-engineered donors, clinical immunosuppression (IS) and modalities to diagnose and treat delayed xenograft rejection (DXR) leading to preclinical studies of CXTx. Prolonged xenograft survival is now limited by non-Gal antibody-mediated DXR (NGDXR). With improved outcomes for orthotopic (OCXTx), it has emerged that early xenograft function is compromised in up to 50% of cases. We have termed this perioperative cardiac xenograft dysfunction (PCXD). For potential future clinical application of CXTx, it is essential to understand the mechanisms and improve the outcomes of both NGDXR and PCXD. All transplants for Specific Aims (SA) 1-3 will use donors transgenic for CD55 with inactivation of the GGTA-1 glycosyltransferase locus (GTKO:CD55+). In SA 1, to better understand PCXD, plasmapheresis will be used to remove preformed non-Gal antibody (PNGA) and the proteasome inhibitor Bortezomib given to delete plasma cells prior to OCXTx. This therapy will also be combined with cariporide cardiac preservation to mitigate preoperative injury. The impact of PNGA depletion and cariporide treatment on PCXD will be assessed by measurement of cardiac function by echocardiography (ECHO), biochemical markers of cardiac injury, recipient antibody and plasma cell levels, and will be correlated with cardiac gene expression in interim biopsies and explanted hearts. In SA 2, to prevent DXR optimal IS based on induction therapy for B- and T-cells, triple drug IS and Bortezomib will be used to control NGA in OCXTx recipients surviving SA 1. We will further study the mechanism(s) of NGDXR through analysis of antibody responses to GTKO PAECs and novel individual non-Gal carbohydrate and protein target antigens we have identified. Changes in cardiac gene expression will be correlated with DXR. In SA 3, we utilize life-supporting intrathoracic heterotopic CXTx, a currently clinically used heart transplant variant which, as well as being a potential technique for initial clinical application of CXTx, will uniquely allow a) observation of recovery of PCXD by ECHO and b) development of methods for the diagnosis and treatment of DXR without loss of the recipient as the native heart supports the circulation during these periods of xenograft dysfunction. In this aim, plasmapheresis and Bortezomib will be used to treat DXR. The objective of this application, to achieve 3-month median survival of circulation-bearing CXTx, if successful, will lay the groundwork for preclinical studies during this grant period to support clinical application of CXTx. RELEVANCE: Successful xenotransplantation offers a potential clinical solution to alleviate the chronic and increasing shortage of donor organs and cells for transplantation. Our previous studies over 12 years have achieved the longest median survival of heterotopic cardiac xenotransplants and the longest survivors of life-supporting orthotopic cardiac xenotransplants. Achievement of the specific aims of this proposal will bring cardiac xenotransplantation to the threshold of clinical application.