Pig to human thymic xenotransplantation

猪至人胸腺异种移植

• 批准号: 7986440
• 负责人: Megan Sykes
• 金额: $ 50.89万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-05-01 至 2015-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7986440
• 关键词: Adolescent; Adult; Allogenic; Antibody Formation; Antigens; B-Lymphocytes; Bypass; Cell physiology; Cells; Chimerism; Data; Defect; Epithelium; Failure; Family suidae; Gene Transfer Techniques; Graft Rejection; Hematopoietic stem cells; Human; Immune; Immunodeficient Mouse; Immunoglobulin Class Switching; Immunosuppression; Implant; Mus; Organ; Peripheral; Phenotype; Proteins; Regulatory T-Lymphocyte; Role; System; T cell response; T-Lymphocyte; Therapeutic immunosuppression; Thymic epithelial cell; Thymus Gland; Toxic effect; Transplantation; Xenograft procedure; clinical application; fetal; immune function; implantation; kidney xenograft; mouse model; nonhuman primate; prevent; public health relevance; reconstitution; thymus xenograft

DESCRIPTION (provided by applicant): The severe shortage of allogeneic donors currently limits the number of transplants performed. This supply-demand disparity could be corrected by the ability to use organs from other species (xenografts), but the immune barriers to xenografts make it unlikely that non-specific immunosuppression could prevent rejection without unacceptable toxicity. Induction of specific tolerance would overcome the need for non-specific immunosuppressive therapy. We have developed a humanized mouse model that allows the reconstitution of immunodeficient mice with human T and B cells and APCs. These human cells demonstrate robust immune function, including xenograft rejection, proliferative T cell responses and class-switched antibody responses to protein antigens. We have also shown that normal, polyclonal human T cells can develop in porcine thymic xenografts that replace the human thymus graft in this humanized mouse model. These human T cells are specifically tolerant to the porcine thymus donor, suggesting an approach to achieving xenograft tolerance in humans. The xenogeneic thymus transplant approach has allowed porcine kidney xenograft survival in non- human primates. However, data obtained in the humanized mouse model suggest that there may be defects in human T cell function in pig thymus xenografted mice resulting from a failure of the T cells that are positively selected on porcine thymic epithelium to interact optimally with HLA molecules on human APCs in the periphery. We have obtained evidence in the pig-mouse combination that implantation of recipient thymic epithelial cells with the porcine thymus xenograft can overcome such defects. We now aim to develop strategies to bypass the consequences of MHC incompatibility between porcine thymic epithelium and peripheral human APCs in the pig-human system. The effect of co-implantating human thymic epithelial cells (huTEC) in the porcine thymic grafts will be explored, using fetal, juvenile and adult huTEC. A second approach will be to provide porcine APCs in the periphery by inducing mixed xenogeneic chimerism in xenogeneic thymus-grafted humanized mice. We will examine the effects of these manipulations on peripheral T cell responses, homeostatic expansion and phenotypic conversion, survival, and Treg function and phenotype. Additionally, we aim to evaluate the mechanisms of tolerance to pig and human donor antigens of T cells generated in porcine thymus grafts. The role of deletion of T cells with TCR recognizing pig donor antigens will be explored using human TCR transgenesis into human hematopoietic stem cells. The role of regulatory T cells and the effect of huTEC implantation on regulatory cell function will be explored. The results of these studies will advance this promising approach to xenograft tolerance induction toward clinical application. PUBLIC HEALTH RELEVANCE: The severe shortage of allogeneic donors currently limits the number of transplants performed. This supply-demand disparity could be corrected by the ability to use organs from other species (xenografts), but the immune barriers to xenografts make it unlikely that non-specific immunosuppression could prevent rejection without unacceptable toxicity. We have developed an approach to achieving xenograft tolerance among human T cells, thereby avoiding the need for non-specific immunosuppression and we now propose studies that will advance this promising approach toward clinical application.

描述（由申请人提供）：同种异体供体的严重短缺目前限制了进行的移植数量。使用其他物种（异种移植物）的器官的能力可以纠正这种供求需求的差异，但是异种移植物的免疫屏障使得非特异性免疫抑制不可能防止排斥反应而不会获得不可接受的毒性。特定耐受性的诱导将克服对非特异性免疫抑制治疗的需求。我们已经开发了一种人源化的小鼠模型，该模型允许与人T和B细胞和APC重构免疫缺陷小鼠。这些人类细胞表现出强大的免疫功能，包括异种移植排斥，增殖性T细胞反应和对蛋白质抗原的类切换抗体反应。我们还表明，在这种人源性小鼠模型中，猪胸腺异种移植物可以替代人胸腺移植物中正常的多克隆人T细胞。这些人T细胞对猪胸骨供体特别耐受，这表明一种实现人类异种移植耐受性的方法。异构胸腺移植方法允许非人类灵长类动物的猪肾异种移植物存活。然而，在人源化小鼠模型中获得的数据表明，猪胸腺异种移植小鼠的人T细胞功能可能存在缺陷，这是由于T细胞在猪胸腺上皮上阳性阳性选择的衰竭而导致的，可在外围人类APC上与HLA分子最佳相互作用。我们已经在猪鼠组合中获得了证据，表明受体胸腺上皮细胞用猪胸腺异种移植物植入可以克服此类缺陷。现在，我们旨在制定策略，以绕过猪人类系统中猪胸腺上皮和外周人APC之间MHC不兼容的后果。将使用胎儿，少年和成年HUTEC探索猪胸腺移植物中植入猪胸腺移植物中的人类胸腺上皮细胞（HUTEC）的影响。第二种方法是通过在异构胸腺植血的人源化小鼠中诱导混合异构嵌合物来提供外围的猪APC。我们将研究这些操纵对周围T细胞反应，稳态扩张和表型转化，生存以及Treg功能和表型的影响。此外，我们旨在评估对猪胸腺移植物中T细胞的耐受性和人类供体抗原的耐受性的机制。使用人类TCR转基因在人类造血干细胞中探索TCR识别猪供体抗原的TCR缺失的作用。将探讨调节性T细胞的作用以及HUTEC植入对调节细胞功能的影响。这些研究的结果将推动这种有希望的异种移植耐受性诱导临床应用的方法。 公共卫生相关性：同种异体供体的严重短缺目前限制了进行的移植数量。使用其他物种（异种移植物）的器官的能力可以纠正这种供求需求的差异，但是异种移植物的免疫屏障使得非特异性免疫抑制不可能防止排斥反应而不会获得不可接受的毒性。我们已经开发了一种在人T细胞中实现异种移植耐受性的方法，从而避免了对非特异性免疫抑制的需求，现在我们提出的研究将推进这种有希望的临床应用方法。