组织工程软骨技术是关节软骨损伤修复的重要研究方向。软骨脱细胞基质(cdECM)因具有和天然软骨成分相近的优点而受到关注，但cdECM力学性能差及仿生结构破坏限制了其应用。近年来关节腔注射间充质干细胞外泌体（MSCs-Exos)成为治疗软骨损伤的重要研究方向之一，但此种方法生物利用度低且需要反复注射。我们前期利用3D打印构建了仿生软骨结构的丝素蛋白（SF）/明胶支架，SF弥补了明胶力学不足特性，效果良好；此外我们以SF为核心设计了一套新的药物缓释方案。基于以上背景和基础，本项目拟研究SF缓释药物的机制及规律，首次实现SF对MSCs-Exos的缓释调控；并将SF与cdECM结合改善力学性能；最后通过3D生物打印进行结构重塑，实现对软骨多层级结构的模拟。该支架可在软骨损伤区域定向释放并保留MSCs-Exos，通过诱导软骨细胞迁移、增殖并为细胞代谢提供力学和空间微环境，从而促进损伤软骨再生修复。

Cartilage tissue engineering is an important research direction of articular cartilage defects repair. Cartilage decellularized extracellular matrices(cdECM) has attracted attention because of its similarity with natural cartilage components, but the poor mechanical properties of cdECM and the destruction of bionic structures have limited its application range. In recent years, intra-articular injection of mesenchymal stem cell exosomes (MSCs-Exos) has become one of the most important research directions for the treatment of cartilage defects, but this method has low bioavailability and requires repeated injections. In our previous work, silk fibroin (SF) was used to compensate the low mechanics of collagen, and the bionic cartilage structure was achieved by 3D printing. The effect was excellent and achieved recognition form authorized journal. In addition, we designed a new drug sustained release solution with SF as the core component. Based on the above research background and our work basis, this research intends to 1) study the mechanism and clarify its effect of SF sustained-release drugs, and realize the sustained-release regulation of MSCs-Exos in SF for the first time; and 2) combine SF with cdECM to improve its mechanical properties; 3) perform 3D bioprinting to mimic the multi-layer structure of cartilage. The scaffold can release MSCs-Exos in the cartilage injury area, and promote the regeneration and repair of damaged cartilage by inducing chondrocyte migration, proliferation and providing mechanical and spatial microenvironment for cell metabolism.