Repair of osteochondral defects mediated by double-layer scaffolds with natural osteochondral-biomimetic microenvironment and interface.

Tissue engineering provides a new approach for the treatment of osteochondral defects. However, the lack of an ideal double-layer scaffold with osteochondral-biomimetic microenvironment and interface similar to native articular tissue greatly limits clinical translation. Our current study developed a double-layer acellular osteochondral matrix (AOM) scaffold with natural osteochondral-biomimetic microenvironment and interface by integrating ultraviolet (UV) laser and decellularization techniques. The laser parameters were optimized to achieve a proper pore depth close to the osteochondral interface, which guaranteed complete decellularization, sufficient space for cell loading, and relative independence of the chondrogenic and osteogenic microenvironments. Gelatin-methacryloyl (GelMA) hydrogel was further used as the cell carrier to significantly enhance the efficiency and homogeneity of cell loading in the AOM scaffold with large pore structure. Additionally, results demonstrated that the components of the AOM scaffold could efficiently regulate the chondrogenic/osteogenic differentiations of bone marrow stromal cells (BMSCs) by activating the chondrogenic/osteogenic related pathways. Importantly, the AOM scaffolds combined with BMSC-laden GelMA hydrogel successfully realized tissue-specific repair of the osteochondral defects in a knee joint model of rabbit. The current study developed a novel double-layer osteochondral biomimetic scaffold and feasible strategy, providing strong support for the tissue-specific repair of osteochondral defects and its future clinical translation.