Studies in pig-to-primate cardiac xenotransplantation

猪到灵长类动物心脏异种移植的研究

• 批准号: 6987516
• 负责人: CHRISTOPHER G.A. MCGREGOR
• 金额: $ 88.15万
• 依托单位: MAYO CLINIC ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6987516
• 关键词: antigen antibody reaction; baboons; biopsy; blood chemistry; genetic manipulation; genetically modified animals; graft versus host disease; heart function; heart transplantation; immune response; immunocytochemistry; immunologic assay /test; immunopathology; immunosuppressive; nonhuman therapy evaluation; swine; transplant rejection; transplantation immunology; xenotransplantation

DESCRIPTION: The broad long-term objective of this application is to achieve sustained life-supporting cardiac xenograft survival in the pig-to-primate model using a protocol consisting of a genetically-engineered donor heart, a combination of currently available immunosuppressive drugs and techniques, and modalities to detect and treat rejection episodes that will allow clinical application of cardiac xenotransplantation. Pig-to-primate xenotransplantation (XTx) has been limited by antibody mediated rejection (AMR) initially to the Galactose a -1,3 Galactose (a-Gal) antigen. Anti-Gal AMR has been prevented in our laboratory using a-Gal polymers and specific immunosuppressive (IS) regimens. After 7 years of XTx research a median survival of 96 days in heterotopic transgenic pig heart to baboon transplants has been achieved. In the orthotopic, life-supporting position, survival of over 5 and 8 weeks has been reached, the best outcomes to date. As an alternative to a-Gal polymers, we have bred homozygous pigs deficient in the synthesis of the a-Gal antigen (GGTA1-KO). Recent heterotopic transplants with GGTA1-KO donors exhibit similar prolonged survival. Despite eliminating anti-Gal antibody, the xenograft (Xg) is rejected by a non-Gal anti-pig antibody response. The overall hypotheses of this proposal are 1) that the optimal pig donor to resist AMR is a GGTA1-KO;hCRP transgenic; 2) the use of clinically applied immunosuppression can result in prolonged cardiac Xg function in the absence of a-Gal antigen; and 3) that Xg rejection can be diagnosed and treated by current methods for antibody control in patients with preformed antibodies. The proposal has three specific aims. Specific Aim 1, to determine the preferred transgenic donor for pig-to-primate cardiac XTx by comparing survival, histology, immunohistology and immune responses using GGTA1-KO and GGTA1-KO;hCRP donor organs. The outcome addresses a central issue in pig-to-primate XTx, namely the role of the a-Gal antigen and the impact of hCRP's, on both graft outcomes and mechanisms of rejection. Furthermore, this work will define the base genetics that should be used for future genetic modifications. Specific Aim 2 is to identify the minimal level of immunosuppression compatible with prolonged organ survival. Using donor organs defined in SA 1 these experiments will determine whether an immunosuppressive regimen based on current clinical IS for presensitized allograft recipients can control Xg rejection resulting in prolonged Xg survival. These experiments will define the relative contribution of basal IS and therapies that seek to block indirect antigen presentation and T-cell help. Specific Aim 3 is to use orthotopic cardiac XTx to define the physiological function of the Xg and identify parameters (functional, biochemical, hematological and biophysical) that allow the detection of rejection and test methodologies to reverse these events. While Xg failure is associated with the presence of anti-pig antibody there is as yet no definitive proof that rejection is antibody mediated. These life-supporting transplants will allow the development of methods to accurately detect rejection based on cardiac function. In addition, by attempting to reverse rejection episodes with plasmapheresis we will identify the initiating mechanism of graft rejection. This proposal, if successful, lays the groundwork for the clinical application of cardiac XTx.

DESCRIPTION: The broad long-term objective of this application is to achieve sustained life-supporting cardiac xenograft survival in the pig-to-primate model using a protocol consisting of a genetically-engineered donor heart, a combination of currently available immunosuppressive drugs and techniques, and modalities to detect and treat rejection episodes that will allow clinical application of cardiac xenotransplantation.最初对半乳糖A -1,3半乳糖（A-GAL）抗原的抗体介导的抑制（AMR）限制了猪至顶峰的异种移植（XTX）。使用A-GAL聚合物和特定的免疫抑制（IS）方案，我们的实验室中已经阻止了抗GAL AMR。经过7年的XTX研究，在异位转基因猪心中为狒狒移植的中位数为96天。在原位，支持生命的位置中，已经达到了超过5周和8周的生存，这是迄今为止的最佳结果。作为A-GAL聚合物的替代方法，我们繁殖了纯合猪在A-GAL抗原（GGTA1-KO）的合成中缺乏。 GGTA1-KO供体最近的异位移植物表现出相似的长期生存期。尽管消除了抗-GAL抗体，但异种移植（XG）被非GAL抗弱抗抗体反应拒绝。该提案的总体假设是1）抗AMR的最佳猪供体是GGTA1-KO; HCRP转基因； 2）在没有A-GAL抗原的情况下，使用临床施用的免疫抑制会导致心脏XG功能延长； 3）可以通过当前的预先抗体控制方法诊断和治疗XG排斥反应。该提案具有三个具体目标。具体目标1，通过使用GGTA1-KO和GGTA1-KO进行生存，组织学，免疫组织学和免疫反应来确定首选的转基因供体，用于猪到顶峰的心脏XTX。该结果解决了猪至顶峰XTX中的一个核心问题，即A-GAL抗原的作用以及HCRP对移植结果和拒绝机制的影响。此外，这项工作将定义应用于未来遗传修饰的基础遗传学。具体目的2是确定与长时间器官生存兼容的免疫抑制水平的最低水平。使用SA 1中定义的供体器官，这些实验将确定基于当前临床的免疫抑制方案是否用于预知的同种异体移植受体可以控制XG排斥反应，从而导致XG生存率延长。这些实验将定义基础IS的相对贡献和试图阻止间接抗原表现和T细胞帮助的疗法。具体目的3是使用原位心脏XTX来定义XG的生理功能，并识别参数（功能，生化，血液学和生物物理），从而允许检测排斥和测试方法来逆转这些事件。尽管XG衰竭与抗铅抗体的存在有关，但尚无确切的证据表明排斥反应是介导的抗体。这些支持生命的移植将使方法的开发能够根据心脏功能准确检测排斥。此外，通过尝试逆向拒绝发作，我们将确定移植排斥的启动机制。该提案（如果成功）为心脏XTX的临床应用奠定了基础。