Application of miR-29a-Exosome and multifunctional scaffold for full-thickness cartilage defects

Full-thickness cartilage defect is a common refractory disease in orthopedics. In this study, we designed a novel composite scaffold composed of silk fibroin-chitosan for the cartilage layer and porous tantalum for the subchondral bone layer, loaded with engineered bone mesenchymal stem cell exosomes, to evaluate its efficacy in repairing full-thickness cartilage defect. Porous tantalum was 3D printed and combined with silk fibroin-chitosan to form a composite scaffold. Chondrocytes were cultured on the scaffold, and their growth was assessed using the CCK-8 method. Toluidine blue staining confirmed cell morphology, while immunofluorescence revealed collagen type Ⅱ expression. Engineered exosomes loaded with miR-29a were created and characterized using various techniques. Co-culturing with chondrocytes demonstrated their proliferation over 10 days. Immunofluorescence revealed staining for the nucleus, collagen type II, and Aggrecan. In vivo experiments were performed on rats to assess cartilage defect repair, utilizing histological staining and micro-CT scanning at 4 and 8 weeks post-operation. The silk fibroin-chitosan scaffold demonstrated good biocompatibility, supporting chondrocyte adhesion, growth, and cartilage tissue formation. Engineered exosomes exhibited promising biological activity, conducive to bone and cartilage regeneration. The implantation of the silk fibroin-chitosan/porous tantalum composite scaffold loaded with engineered exosomes promoted integration with the surrounding bone and cartilage tissues, facilitating repair and regeneration. The silk fibroin-chitosan combined with porous tantalum scaffold carrying engineered exosomes loaded with miR-29a has good potential for full-thickness cartilage defects regeneration.