Enhancing BMSC chondrogenesis with a dynamic viscoelastic hyaluronan hydrogel loaded with kartogenin for cartilage repair

Hydrogel-based cartilage tissue engineering (HCTE) offers a promising strategy for the regeneration of articular cartilage. However, the effectiveness of current HCTE is hindered by the low efficiency of stem cell transplantation and insufficient chondrogenic differentiation. Here, we develop a mechanically optimized and biochemically sustained biomaterial system that integrates a dynamic hydrazone/covalent dual-crosslinked hyaluronan (HA) hydrogel with kartogenin (KGN)-loaded poly(lactic-co-glycolic acid) microspheres to facilitate stem cell chondrogenesis and repair articular cartilage. This composite hydrogel features excellent injectability and self-healing behavior, allowing for minimally invasive implantation while protecting cell viability. The tunable viscoelasticity of the hydrogel enhances focal adhesion formation in bone-marrow mesenchymal stem cells (BMSCs), promoting their spreading, proliferation, and aggregation. Furthermore, the combined effects of hydrogel viscoelasticity and sustained KGN release markedly promote the expression of cartilage-specific genes and the secretion of extracellular matrix components through the integrin-mediated Hippo signaling pathway and KGN-mediated TGF-β signaling pathway. This dual-stimuli hydrogel embedded with BMSCs significantly promotes the regeneration of articular cartilage in rabbit models. Overall, the designed KGN composite dynamic HA-based hydrogel enables highly effective transplantation and promotes efficient chondrogenesis of stem cells, providing a promising approach for stem cell therapy and cartilage regeneration.