仿生软骨ECM“分子油漆”修复关节表面软骨缺损的研究

Osteoarthritis is often accompanied by partial-thickness cartilage defects on the joint surface, which is difficult to repair and is still a clinical challenge. In this project, inspired by renovation strategy of automobile spray paint, a new kind of "molecular paint" consists of the components of cartilage ECM will be designed to treat partial-thickness cartilage defect of osteoarthritis. The "molecular paint" will be designed with tissue adhesion, compression resistance, cell affinity, and easy operation. Conventional paints use polymer aggregation or polymerization to form a polymer film on the surface of the object, but organic solvents and violent chemical reactions are not suitable for in vivo applications. This project intends to use collagen derivative gelatin as film-forming substance of "paint" and water as solvent so that gelatin can be polymerized on cartilage surface in-situ by UV-crosslinking. Moreover, chondroitin sulfate and hyaluronic acid will be modified and serve as additives to increase the adhesion and crosslinking point of "paint" by means of Schiff base. Controlled chemical modification allows these components to achieve the above functions while maintaining biological activity, so "molecular paint" not only has protective properties, mechanical properties, but also cell affinity. This project will study the design of "molecular paint" materials, the interaction between stem cells and materials, and the mechanism of repairing partial-thickness cartilage defects, laying the foundation for clinical transformation.

骨关节炎常伴有关节表面的非全层软骨缺损，修复困难，目前仍是临床上的挑战。本项目借鉴汽车喷漆翻新的策略，采用软骨ECM的组分，设计一种具有组织黏附力的、抗压的、细胞亲和力强的、而且便于操作的“分子油漆”，用来治疗骨关节炎的非全层软骨缺损。传统油漆利用高分子脱溶剂后的聚集或聚合反应在物体表面形成高分子膜，但是有机溶剂和剧烈的化学反应不适合生物体内应用。本项目拟采用胶原的衍生物明胶作为“油漆”的成膜物，水作为溶剂，通过光交联的方式使明胶在软骨表面聚合成膜，同时创新性地加入硫酸软骨素和透明质酸作为助剂，通过席夫碱的方式增加“油漆”的黏附力和交联点。可控的化学改性使这些组分获得以上功能，同时保持生物活性，因此“分子油漆”不仅拥有保护性能、机械性能，还具有细胞亲和性。本项目将研究“分子油漆”材料的设计，干细胞与材料的相互作用关系，以及修复非全层软骨缺损的机制，为临床转化奠定基础。

针对临床上难修复的关节表面大面积、不规则的非全层软骨缺损，本项目借鉴汽车喷漆翻新的策略，采用软骨细胞外基质（ECM）的组分，设计了一种具有组织黏附力的、抗压的、细胞亲和力强的、而且便于操作的“分子油漆”。本项目采用胶原的衍生物明胶作为“油漆”的成膜物，通过可控的化学反应，使其保持生物活性的同时具有光固化的性能，以水为溶剂，结合透明质酸在软骨表面聚合形成了半互穿网络的水凝胶膜。同时，对硫酸软骨素氧化在其分子结构上产生一定量的醛基，进而作为桥接分子通过席夫碱的方式增加“油漆”的黏附力和交联点，研究发现当使用氧化硫酸软骨素作为桥接分子时，“油漆”的软骨表面粘附力大大提高，体外实验表明材料能在软骨表面驻留4个月以上。可控的化学改性除了使这些仿生组分获得了抗压和粘附的材料学功能，同时还保持了必要生物活性，研究结果显示“分子油漆”能支持干细胞的粘附与增殖，当与易丢失表型的软骨细胞的相互作用时，结果表明材料能维持软骨细胞的表型并且促进软骨相关基因的高表达。体内功能验证以新西兰大白兔为动物模型，结果表明软骨表面损伤后未做处理易导致软骨基质的进一步降解，而经过“分子油漆”处理后，软骨基质降解和软骨细胞凋亡的情况都得到了改善，同时也观察到了软骨基质的再生。以上“分子油漆”的基础研究为非全层软骨缺损修复提供了新的思路，也为其临床转化奠定了基础。