Tolerance Induction in a GAIT-KO Pig-to-Baboon Model Through Establishment ......

以前跨越猪到灵长类的异种障碍实现混合嵌合体的尝试都 失败，主要是由于细胞上表达的灵长类天然抗体Gal抗原水平较高 所有成熟猪的造血细胞表面。因此，遵循混合嵌合体诱导方案 在非人类灵长类动物中，我们有证据表明猪造血干细胞可以长期植入 (HSC)，似乎不表达Gal。然而，尽管抗体被吸收，但抑制 补体和各种药物治疗，天然抗Gal抗体持续存在和/或复发，以及 似乎在抑制猪HSC的后代重新繁殖灵长类动物方面发挥了重要作用 收件人。半乳糖基转移酶(Gal-T)基因敲除猪(Gal-KO)的最新可用性，衍生 从我们最高度近亲繁殖的小型猪品系，现在已经使研究猪到狒狒成为可能 在没有天然抗Gal抗体影响的异种移植中。这样做的目的是 建议利用这些新的Galt-KO动物作为造血细胞捐赠者 猪-狒狒混合异种嵌合体的建立。我们的上一个 研究和我们的初步数据都表明，应用混合嵌合体方法是可行的 为了跨越这一障碍诱导移植耐受，一种已经在 这个实验室用于啮齿动物、猪和食蟹猴的同种异种移植和融合性异种移植。 具体地说，我们将：1)优化Galt-KO小型猪的HC在 2)检查选定的先天免疫和非免疫的作用 促进和/或抵制Galt-KO HCin狒狒嫁接的因素；以及3)测试 GALT-KO猪HC移植在狒狒体内诱导耐受的作用 随后异种器官移植的接受者。具体而言，目标3将适用目标1的调查结果。 和2，以及在本计划项目的其他项目中制定的战略，给混合 嵌合体方法诱导异种器官移植耐受， 不协调的物种组合。此外，计划中的实验将提供关于 异种干细胞移植及其致病免疫途径的研究进展 灵长类动物的排斥和耐受诱导。因此，这些研究应该既有理论上的，也有 异种移植作为一种临床方式最终应用的实际意义。

Previous attempts to achieve mixed chimerism across the xenogeneic barrier of pig-to-primate have all failed, largely due to high levels of primate natural antibodies to the Gal antigen, expressed on the cell surface of all mature pig hematopoeitic cells. Thus, following mixed chimerism induction protocols in non-human primates, we have had evidence for long-term engraftment of pig hematopoietic stem cells (HSC), which do not appear to express Gal. However, despite antibody absorptions, inhibition of complement and various drug treatments, natural anti-Gal antibodies persisted and/or recurred, and appeared to play an important role in inhibiting the progeny of pig HSC from repopulating primate recipients. The recent availability of galactosyltransferase (Gal-T) knockout (GalT-KO) swine, derived from our most highly inbred line of miniature swine, has now made it possible to study pig-to-baboon xenotransplantation in the absence of effects of natural anti-Gal antibodies. The goal of this proposal is to utilize these new GalT-KO animals as hematopoietic cell donors for the establishment of mixed xenogeneic chimerism in the pig-to-baboon combination. Ourprevious studies and our preliminary data all suggest the feasibility of applying the mixed chimerism approach to induction of transplantation tolerance across this barrier, an approach already used successfully in this laboratory for allografts and concordant xenografts in rodents, pigs and cynomolgus monkeys. Specifically, we will: 1) Optimize the engraftment of HC from GalT-KO miniature swine in conditioned baboons; 2) Examine the role of selected innate immune and non-immune factors in promoting and/or resisting engraftment of GalT-KO HCin baboons; and 3) Test the role of GalT-KO pig HC engraftment in baboons enabling the induction of tolerance in recipients of subsequent organ xenografts. Aim 3, in particular, will apply the findings of Aims 1 and 2, as well as strategies developed in the other projects of this Program Project, to the mixed chimerism approach for inducing transplantation tolerance to organ xenografts in this preclinical, discordant species combination. In addition, the experiments planned will provide basic information on xenogeneic stem cell engrafment and on the immunologic pathways responsible for xenogeneic rejection and tolerance induction in primates. As such, these studies should have both theoretical and practical implications for the eventual application of xenotransplantation as a clinical modality.