p75受体在富集结膜上皮干细胞中的作用机制及功能性结膜重建的研究

结膜是眼表的重要组成部分，其结构与功能的完整对维持眼表稳态至关重要。临床上眼烧伤、免疫性疾病等导致的结膜瘢痕和重度睑球黏连是难治性眼表疾病，功能性结膜的构建是解决问题的关键。但目前结膜上皮干细胞的体外富集缺少有效的方法，使得结膜重建面临种子细胞来源不足的难题。我们前期研究发现：结膜上皮中存在部分细胞高表达p75，应用免疫磁珠法富集的p75强阳性细胞高表达结膜上皮干性标志物、低表达分化角蛋白，提示其具备良好的干细胞特性；初步将其应用于兔结膜缺损的修复取得了较好的疗效；同时发现p75上游配体NGF/proNGF能够调控结膜上皮细胞分化。因此，本课题将在前期研究基础上进一步验证p75强阳性细胞的干细胞特性，详细检测其在体外构建功能性结膜及对动物结膜缺损修复的能力，并探究NGF-p75-SALL2信号通路调控结膜上皮干细胞分化状态的详细分子机制。研究有望通过结膜再生为治疗瘢痕性眼表疾病提供新方法。

Conjunctiva is an important part of the ocular surface, and its structure and function play a crucial role in maintaining the steady state of ocular surface. The significant conjunctival scarring and severe symblepharon caused by ocular burn and immune diseases are refractory ocular surface diseases, and the reconstruction of functional conjunctiva is the key to solve the problem. However, there is no effective method for the in vitro enrichment of conjunctival epithelial stem cells. Therefore, conjunctival reconstruction is faced with the problem of insufficient seed cells. Our previous study found that a small subset of cells in conjunctival epithelium showed high expression of p75. These p75 strong positive cells enriched by immunomagnetic beads in vitro showed high expression of conjunctival epithelial stem cell markers and low expression of differentiation-associated keratins, indicating that they had good characteristics of conjunctival epithelial stem cells. Preliminary application of these p75 strong positive cells in the repair of large conjunctival defects in rabbits showed satisfactory results. Meanwhile, NGF and proNGF, the upstream ligands of p75, was found to regulate the differentiation of conjunctival epithelial cells. Therefore, on the basis of previous studies, this study will further verify the stem cell characteristics of p75 strong positive cells, test their ability to reconstruct functional conjunctiva in vitro and repair conjunctiva defects in animal models, and explore the detailed molecular mechanism of NGF-p75-SALL2 signaling pathway in regulating the differentiation state of conjunctiva epithelial stem cells. The study is expected to provide a new method for the treatment of cicatricial ocular surface diseases by conjunctival regeneration.