Non-Human Primate Models for Human Xenotransplantation

描述(申请人提供)：使用猪作为人类移植的器官捐赠者，是解决终末期疾病患者可用器官日益短缺的解决方案。然而，野生型猪的器官被先前存在的针对1-D-半乳糖基-(1-&gt；3)-1-D-半乳糖苷(Gal 11，3 al)碳水化合物的天然抗体超急性排斥，这种碳水化合物在猪细胞上表达，在人类中不表达。来自半乳糖基因敲除猪的器官被培育成潜在的捐赠者，但最近来自几个实验室的研究表明，尽管这些器官不会发生超急性排斥反应，但它们仍然会在六个月内被排斥。急性体液排斥反应(AHXR)和血栓形成是移植物死亡的原因之一。已有研究表明，将Gal基因敲除的供体器官移植到非人灵长类动物体内可诱导产生抗Gal异种抗体，但这些抗体的特异性、来源和结构尚未确定。目前可用的免疫抑制药物在预防AHXR方面无效。需要进一步的研究来确定急性体液性异种移植排斥反应发生的原因，并确定预防它的方法。我们的具体目标是对异种抗体的来源和结合特异性进行详细和系统的研究，这些抗体仍然拒绝在移植了转基因器官的非人灵长类动物中进行基因操纵的异种移植。这项工作将为设计一种成功的预防异种移植排斥反应的方法提供缺乏但必要的信息。我们计划在研究中检查的实验样本是在GAL基因敲除背景下培育的，并具有额外的转基因，如CD39，以防止血栓形成。我们将进一步确定一种识别产生异种抗体的B细胞的抗独特型抗体是否能在体内预防AHXR。这项资助提案将扩展我们在上一批资助期间的工作，当时我们定义了编码针对非人类灵长类动物中野生型猪器官的异种抗体的免疫球蛋白基因的结构，并鉴定了一种能够定义产生异种抗体的B细胞的抗独特型抗体。 公共卫生相关性：使用专门培育的猪作为人类移植(异种移植)的器官捐赠者，可以为许多患者提供器官，否则他们可能会等死。在移植物被抗体排斥之前，这些器官可以工作三到六个月。这项研究将确定编码这些抗体的基因，并将测试防止这种抗体反应的新方法。

DESCRIPTION (provided by applicant): The use of pigs as organ donors for human transplantation represents a solution to the escalating shortage of organs that are available for patients with end-stage diseases. Wild type pig organs are hyperacutely rejected, however, by pre-existing natural antibodies directed at the 1-D-galactosyl-(1->3)-1-D-galactoside (gal 11,3gal) carbohydrate, which is expressed on pig, cells and absent in humans. Organs derived from gal knockout pigs have been bred as potential donors, but recent studies from several laboratories have shown that although these organs do not undergo hyperacute rejection, they are still rejected within six months. Acute humoral rejection (AHXR) and thrombosis contribute to the demise of these grafts. Anti-non-gal xenoantibodies have been shown to be induced in non-human primates transplanted with gal knockout donor organs, but the specificity, origin and structure of these antibodies has not been determined. Currently available immunosuppressive drugs are ineffective in preventing AHXR. Additional research is needed to determine why acute humoral xenograft rejection occurs, and to define a means to prevent it. Our specific aims propose a detailed and systematic study on the origin and binding specificity of xenoantibodies that still reject genetically-manipulated xenografts in non-human primates transplanted with genetically-modified organs. This work would provide information that is lacking but necessary for the design of a successful approach to preventing xenograft rejection. The experimental samples that we plan to examine in our study have been bred on a gal knockout background and have additional transgenes such as CD39 to prevent thrombosis. We will further determine whether an anti-idiotypic antibody that identifies B cells producing xenoantibodies will prevent AHXR in vivo. This grant proposal will extend our work in the previous grant period in which we defined the structure of immunoglobulin genes encoding xenoantibodies to wild type pig organs in non-human primates and have identified an anti-idiotypic antibody with the ability to define B cells producing xenoantibodes. PUBLIC HEALTH RELEVANCE: The use of specifically bred pigs as organ donors for human transplantation (xenotransplantation) could provide organs for the many patients who may otherwise die waiting. These organs function for three to six months before the grafts are rejected by antibodies. This study will identify the genes that encode these antibodies and will test novel ways to prevent this antibody response.