ECM-Mimicking Hydrogels Loaded with Bone Mesenchymal Stem Cell-Derived Exosomes for the Treatment of Cartilage Defects

It is well-established that treating articular cartilage injuries is clinically challenging since they lack blood arteries, nerves, and lymphoid tissue. Recent studies have revealed that bone marrow stem cell-derived exosomes (BMSCs-Exos) exert significant chondroprotective effects through paracrine secretions, and hydrogel-based materials can synergize the exosomes through sustained release. Therefore, this research aims to synthesize an ECM (extracellular matrix)-mimicking gelatin methacryloyl (GelMA) hydrogel modified by gelatin combined with BMSCs-derived exosomes to repair cartilage damage. We first isolated and characterized exosomes from BMSCs supernatant and then loaded the exosomes into GelMA hydrogel to investigate cartilage repair effects in in vitro and in vivo experiments. The outcomes showed that the GelMA hydrogel has good biocompatibility with a 3D (three-dimensional) porous structure, exhibiting good carrier characteristics for exosomes. Furthermore, BMSCs-Exos had a significant effect on promoting chondrocyte ECM production and chondrocyte proliferation, and the GelMA hydrogel could enhance this effect through a sustained-release effect. Similarly, in vivo experiments showed that GelMA-Exos promoted cartilage regeneration in rat joint defects and the synthesis of related cartilage matrix proteins.