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: 7256241
• 负责人: CHRISTOPHER G.A. MCGREGOR
• 金额: $ 85.99万
• 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/7256241
• 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.

产品说明：本申请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的组合以及检测和治疗排斥事件的模式组成的方案，在猪-灵长类动物模型中实现持续的生命支持心脏异种移植物存活，这将允许心脏异种移植的临床应用。猪到灵长类动物异种移植（XTx）受到最初针对半乳糖α-1，3半乳糖（α-Gal）抗原的抗体介导的排斥（AMR）的限制。在我们的实验室中，使用α-Gal聚合物和特异性免疫抑制（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为96天。在原位，生命支持的位置，生存超过5和8周已经达到，迄今为止最好的结果。作为α-Gal聚合物的替代物，我们培育了α-Gal抗原合成缺陷的纯合猪（GGTA 1-KO）。最近使用GGTA 1-KO供体的异位移植表现出类似的延长存活。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。该提议的总体假设是1）抵抗AMR的最佳猪供体是GGTA 1-KO;hCRP转基因; 2）在不存在α-Gal抗原的情况下，临床应用的免疫抑制的使用可导致心脏Xg功能延长;以及3）Xg排斥可通过当前的抗体控制方法在具有预先形成的抗体的患者中进行诊断和治疗。该提案有三个具体目标。具体目的1，通过比较使用GGTA 1-KO和GGTA 1-KO;hCRP供体器官的存活率、组织学、免疫组织学和免疫应答，确定猪至灵长类动物心脏XTx的首选转基因供体。结果解决了猪到灵长类XTx中的中心问题，即α-Gal抗原的作用和hCRP对移植物结果和排斥机制的影响。此外，这项工作将确定应用于未来遗传修饰的基础遗传学。具体目标2是确定与延长器官存活相容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的免疫抑制方案是否可用于预致敏的同种异体移植物接受者控制Xg排斥，从而延长Xg存活。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、生化、血液学和生物物理学）和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，但尚未有明确的证据表明排斥反应是抗体介导的。这些支持生命的移植将允许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反应的起始机制。该方案如果成功，将为心脏XTx的临床应用奠定基础。