Evaluation of the carbohydrate antigen-mediated donor rejection in xenotransplantation

在资助期间，我们进行了一项研究，以评估碳水化合物抗原介导的供体器官排斥在拟议的异种移植过程中。近年来，人体供器官的短缺使得异种移植（非人对人移植）成为满足需求的供器官来源。由于猪与人类的大小相似，氨基酸序列同源性较高，因此猪有望成为制备供器官的合理选择。然而，这两种动物在细胞表面碳水化合物抗原的表达有很大的不同。为了验证人类缺乏的n -乙酰神经氨酸羟化酶基因的抗原性，我们建立了缺乏功能性cmp - n -乙酰神经氨酸羟化酶基因的小鼠系。本研究的主要成果如下。(1) CMP-NeuAc羟化酶的靶向诱变重建了人类细胞中已知缺乏活性羟化酶及其产物NeuGc的NeuGc缺失。(2)我们分析了这些可能影响器官排斥点的小鼠的免疫系统发育，发现该小鼠系在稳定状态下具有正常的免疫系统。(3)我们将这一基于es的种系突变回交到C57Black/6系，为器官移植准备供体器官。现在回交的代数是17代，在MHC和其他基于蛋白质的抗原类型方面，供体和受体之间的背景相似性预计是相当强的。

During the grant period, we conducted a research to evaluate the carbohydrate antigen-medi-ated donor organ rejection in the proposed xenoplantation procedure. Recently, shortage of donor organs from human source for the transplantation made xenoplantation (non-human to human transplantation) a rationale source of donor organ to be transplanted to meet the demand. Here, porcine is expected as the logical choice of animal for the preparation of donor organs because of their similarity in size and relative higher amino- acid sequence homology between human. However these two animal species considerably differ for their expression of the carbohydrate antigens in their cell surface. To verify the antigenicty of the N-glycolylneuraminic acid (NeuGc) which human lacks, we developed the mouse line lacking functional CMP-N-acetylneuraminic acid hydroxylase gene. Major achie- vements in this study are as follows.(1) The targeted mutagenesis of CMP-NeuAc hydroxylase re-created the lack of NeuGc in human that is known to lack active hydroxylase and its product NeuGc in cells.(2) We analyzed the immune system development in these mice that may affect the point of organ rejection and found that this mouse line has normal immune system in steady state.(3) We backcrossed this ES-based germline mutation to C57Black/6 line to prepare the donor organ for organ transplantation. Now the number of generations backcrossed is 17 and back- ground similarity between donor and recipient is expected to be quite strong concerning types of MHC and other protein-based antigens.