Fullerol Initiates Stem Cell–Nanomaterials Interactions for Enhanced Tissue Regeneration via Clathrin-Mediated Endocytosis and Nuclear Factor Erythroid 2-Related Factor 2 Signaling

The advancement of nanomedicine requires a thorough understanding of the intrinsic bioactivity and molecular interactions of nanomaterials for safe and effective clinical applications, which remains lacking for most currently developed nanomaterials. Here, we uncover the unique intrinsic bioactivity and regulatory mechanisms of carbon-based fullerol nanomaterials through high-throughput molecular analysis and explore their therapeutic potential for tissue regeneration using tissue engineering approaches. Fullerol exhibits intrinsic pro-differentiation and antioxidant properties that enhance the osteogenesis and chondrogenesis of MSCs. Mechanistically, proteomic analysis combined with small-molecule inhibition studies reveals that fullerol is internalized by MSCs via clathrin-mediated endocytosis and activates NRF2 signaling, thereby exerting antioxidant effects that restore impaired MSC viability and differentiation under oxidative stress. Leveraging these unique bioactivities, we develop a fullerol-functionalized hydrogel with feasible physicochemical properties and triple biological functions in antioxidant, pro-osteogenic, and pro-chondrogenic effects and confirm its great regenerative capacity for both cartilage and subchondral bone by promoting structural restoration and improving functional recovery in a rat osteochondral defect model. Our findings offer new insights into the intricate interactions between stem cells and nanomaterials at the cellular and molecular levels and broaden the potential biomedical applications of fullerol for future cartilage and bone regeneration therapies.