载药可注射双网络水凝胶在角膜基质局灶性损伤修复中的应用基础研究

The injury of cornea from infection, mechanical damage and chemical burn, can cause corneal opacity, even blindness. Among them, deep scald wound and chemical burn of cornea can usually lead to corneal stromal deep damage. In order to meet the demand of donated cornea and prevent scarring of injured corneal stroma, we plan to construct a drug-loaded injectable double-network hydrogel in this application as a repairing substitute for focal corneal stromal defects. Based on our previous study, to improve the mechanical property of hydrogels and avoid the damage of suturing, gelatin and hyaluronic acid will be selected and modified with acrylic anhydride and oxidation respectively, different combinations of acrylate gelatin, gelatin and oxidized hyaluronic acid will be made to prepare injectable double-network hydrogel via click chemistry and Schiff-base crosslinking. The effect of curing conditions on the mechanical property and physical-chemical property will be systematically studied. To stop the scarring of corneal defects, rapamycin will be in-situ loaded into the hydrogels to inhibit the transdifferentiating of corneal stromal cells to corneal fibroblast and to myofibroblasts, and finally to stop the scarring of new corneal tissues. This study might provide a novel approach to repairing and regeneration of corneal stroma.

角膜的深度烫伤、化学灼伤及机械划伤会导致深度的基质创伤，需要进行移植以修复受损的角膜基质。为了满足临床对角膜供体的需求，抑制受损角膜基质的瘢痕化，本课题拟通过组织工程学方法构建载药可注射双网络水凝胶用于角膜基质局灶性损伤的修复。在前期基础上，为了改善修复材料的机械性能，减少缝合带来的创伤，拟选用明胶和透明质酸两种天然高分子，并对其进行改性，制备丙烯酸化明胶和氧化透明质酸，并将丙烯酸化明胶、氧化透明质酸和明胶三者按比例组合，利用点击反应和Schiff碱反应制备可注射双网络水凝胶，研究各因素对水凝胶机械性能和其他理化性能的影响。进一步，为了抑制角膜基质的瘢痕化，将雷帕霉素原位负载于可注射双网络水凝胶，在修复受损角膜基质组织的同时，缓慢释放雷帕霉素，调控雷帕霉素靶蛋白，抑制角膜基质细胞纤维化，从而抑制角膜基质瘢痕化，为修复得到透明的角膜基质提供一种新思路。

各种角膜炎症，外伤损及基质层，愈合后均会留下不同程度的瘫痕。因此， 角膜基质层的创伤修复尤为重要。本项目制备了丙烯酸化明胶/氧化透明质酸水凝胶，丙烯酸化明胶/巯基化明胶水凝胶来构建可注射双网络水凝胶，从化学成份和三维结构上对天然角膜进行仿生模拟；利用点 击反应和 Schiff 碱反应两种交联机制增强水凝胶的机械性能，解决水凝胶用于角膜基质修复机械性能不足的问题，同时通过注射的方式进行角膜基质的修复，大大减少角膜移植手术的二次创伤。另一方面，原位负载雷帕霉素于可注射双网络水凝胶网络中，对角膜基质细胞的 mTOR 进行调控，从实验结果看来，抑制角膜基质细胞瘢痕化得到了一定程度的抑制。