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: 7456574
• 负责人: CHRISTOPHER G.A. MCGREGOR
• 金额: $ 85.48万
• 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/7456574
• 关键词: Academic Medical Centers; Address; Allografting; Antibodies; Antibody Formation; Antigen Presentation; Antigens; Binding; Biochemical; Breeding; CD46 Antigen; Cardiac; Clinic; Clinical; Clinical Trials; Compatible; Complement; Condition; Detection; Diagnosis; Engineering; Event; Exhibits; Failure; Family suidae; Foundations; Future; Galactose; Genetic; Graft Rejection; Heart; Heart Transplantation; Histology; Human; Immune; Immune response; Immunosuppression; Immunosuppressive Agents; Industry; Investigation; Laboratories; Life; Mediating; Methodology; Methods; Modality; Modeling; Modification; Organ Donor; Organ Survival; Outcome; Papio; Patients; Pharmaceutical Preparations; Physiological; Plasmapheresis; Polymers; Positioning Attribute; Pre-Clinical Model; Primates; Protocols documentation; Relative (related person); Research; Research Design; Role; Sus scrofa; T-Lymphocyte; Techniques; Testing; Therapeutic immunosuppression; Transgenic Organisms; Transplantation; Treatment Protocols; Week; Work; Xenograft procedure; base; clinical application; day; genetic regulatory protein; heart xenograft; method development; pre-clinical; prevent; research study

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.

描述：该应用的广泛长期目标是使用由基因工程供体心脏、当前可用的免疫抑制药物和技术组合组成的方案，在猪到灵长类动物模型中实现持续生命支持的心脏异种移植存活。 ，以及检测和治疗排斥反应的方式，这将允许心脏异种移植的临床应用。猪到灵长类异种移植 (XTx) 最初受到半乳糖 a -1,3 半乳糖 (a-Gal) 抗原抗体介导的排斥 (AMR) 的限制。我们的实验室已使用 a-Gal 聚合物和特定的免疫抑制 (IS) 方案预防了抗 Gal AMR。经过 7 年的 XTx 研究，异位转基因猪心脏移植到狒狒的中位生存期已达到 96 天。在原位维持生命的位置，已达到超过 5 至 8 周的生存期，这是迄今为止最好的结果。作为 a-Gal 聚合物的替代品，我们培育了缺乏 a-Gal 抗原 (GGTA1-KO) 合成的纯合猪。最近使用 GGTA1-KO 供体进行的异位移植也表现出类似的延长生存期。尽管消除了抗 Gal 抗体，但异种移植物 (Xg) 仍会被非 Gal 抗猪抗体反应排斥。该提案的总体假设是 1) 抵抗 AMR 的最佳猪供体是 GGTA1-KO；hCRP 转基因； 2）使用临床应用的免疫抑制可导致在a-Gal抗原缺失的情况下心脏Xg功能延长； 3) Xg排斥可以通过现有的抗体控制方法来诊断和治疗具有预先形成的抗体的患者。该提案有三个具体目标。具体目标 1，通过使用 GGTA1-KO 和 GGTA1-KO;hCRP 供体器官比较存活率、组织学、免疫组织学和免疫反应，确定猪到灵长类心脏 XTx 的首选转基因供体。该结果解决了猪到灵长类 XTx 的一个核心问题，即 a-Gal 抗原的作用和 hCRP 对移植结果和排斥机制的影响。此外，这项工作将定义用于未来基因改造的基础遗传学。具体目标 2 是确定与延长器官存活相适应的最低免疫抑制水平。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 IS 的预敏同种异体移植受者的免疫抑制方案是否可以控制 Xg 排斥，从而延长 Xg 生存期。这些实验将确定基础 IS 和寻求阻断间接抗原呈递和 T 细胞帮助的疗法的相对贡献。具体目标 3 是使用原位心脏 XTx 来定义 Xg 的生理功能，并确定允许检测排斥反应的参数（功能、生物化学、血液学和生物物理）以及逆转这些事件的测试方法。虽然 Xg 失败与抗猪抗体的存在有关，但目前还没有明确的证据表明排斥反应是由抗体介导的。这些支持生命的移植将有助于开发基于心脏功能准确检测排斥反应的方法。此外，通过尝试用血浆置换术逆转排斥反应，我们将确定移植物排斥的起始机制。该提案如果成功，将为心脏XTx的临床应用奠定基础。