Pig to human thymic xenotransplantation

猪至人胸腺异种移植

• 批准号: 8460096
• 负责人: Megan Sykes
• 金额: $ 46.04万
• 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/8460096
• 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.

描述（由申请人提供）：同种异体供体的严重短缺目前限制了移植的数量。这种供需差异可以通过使用其他物种的器官（异种移植物）来纠正，但异种移植物的免疫屏障使得非特异性免疫抑制不太可能在没有不可接受的毒性的情况下防止排斥反应。诱导特异性耐受将克服对非特异性免疫抑制治疗的需要。我们开发了一种人源化小鼠模型，可以用人类 T 细胞、B 细胞和 APC 重建免疫缺陷小鼠。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别转换抗体反应。我们还表明，正常的多克隆人类 T 细胞可以在猪胸腺异种移植物中发育，从而取代人源化小鼠模型中的人类胸腺移植物。这些人类 T 细胞对猪胸腺供体具有特异性耐受性，这表明了一种在人类中实现异种移植耐受的方法。异种胸腺移植方法使得猪肾异种移植物在非人类灵长类动物中得以存活。然而，人源化小鼠模型中获得的数据表明，猪胸腺异种移植小鼠中的人类 T 细胞功能可能存在缺陷，这是由于在猪胸腺上皮上积极选择的 T 细胞未能与人类 APC 上的 HLA 分子进行最佳相互作用所致。在外围。我们在猪-小鼠组合中获得的证据表明，将猪胸腺异种移植物植入受体胸腺上皮细胞可以克服此类缺陷。我们现在的目标是制定策略，绕过猪-人系统中猪胸腺上皮和外周人 APC 之间 MHC 不相容的后果。将使用胎儿、幼年和成年 huTEC 来探索在猪胸腺移植物中共同植入人胸腺上皮细胞 (huTEC) 的效果。第二种方法是通过在异种胸腺移植的人源化小鼠中诱导混合异种嵌合，在外周提供猪 APC。我们将检查这些操作对外周 T 细胞反应、稳态扩张和表型转换、存活以及 Treg 功能和表型的影响。此外，我们的目标是评估猪胸腺移植物中产生的 T 细胞对猪和人类供体抗原的耐受机制。将通过人 TCR 转基因到人造血干细胞中来探索删除具有识别猪供体抗原的 TCR 的 T 细胞的作用。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前景的异种移植耐受诱导方法走向临床应用。