供体T细胞靶向损伤宿主胸腺上皮细胞（TECs），导致T细胞阴性选择和Tregs增殖受损，由此引起慢性移植物抗宿主病（cGVHD）。因此，恢复TECs增殖是阻止cGVHD的关键。鼠胚胎干细胞来源的胸腺上皮祖细胞（mESC-TEPs）移植到体内可发育为TECs。我们的前期研究表明，移植供体源性mESC-TEPs到cGVHD受体胸腺，诱导了对供体和宿主抗原的免疫耐受，阻止cGVHD发生。由此，我们将用对OVA有特异性反应的TCR转基因鼠OT-I 和OT-II等研究模型，从体内实验和体外实验等多方面证实mESC-TECs和宿主TECs介导阴性选择和支持Tregs发育的能力。此外，我们将用已建立的mESC-TEPs细胞模型，通过CRISPR/Cas9 技术删除mESC-TEPs的Aire基因，探讨Aire在TECs分化和成熟中的作用，并检测 TECs中与Aire结合的相关分子是否参与免疫耐受的调节。

Donor T cells in the grafts can damage thymic epithelial cells (TECs), which not only affects negative T cell selection, but also impairs the generation of regulatory T cells (Tregs), leading to the development of cGVHD. Therefore, restoration or regeneration of TECs is critical for the prevention of cGVHD. Mouse embryonic stem cell (mESC)-derived thymic epithelial progenitors (TEPs), when transplanted in vivo, can further develop into TECs. Our preliminary studies have shown that transplantation of donor-origin mESC-TEPs into cGVHD recipients induces immune tolerance to both donor and host antigens and prevents the development of cGVHD. Based on these results, we will study the mechanisms of the immune tolerance induction by determining whether both mESC-TECs and host TECs are involved in negative selection and Tregs generation. OVA-specific OT-I and OT-II TCR transgenic mice and both in vivo and in vitro studies will be used in these studies. We will then use the mESC-TEPs model that we first established and CRISPR/Cas9 techniques to investigate the role of Aire in medullary（m）TECs maturation and whether Aire-binding molecules are involved in immune tolerance induction.