Efficacy of a multi-component photocrosslinkable hydrogel on localized bone repair and structural consolidation

Injectable hydrogels for bone regeneration face challenges in simultaneously achieving favorable injectability, structural stability, and osteogenic functionality. Here, we developed a multifunctional photocrosslinkable composite hydrogel (GCDH) consisting of gelatin methacryloyl (GelMA), carboxymethyl cellulose (CMC), dopamine methacrylamide (DMA), and hydroxyapatite (HAp). CMC regulated network dynamics and endowed the precursor with shear-thinning and rapid recovery properties, while DMA enhanced wet-state interfacial interactions through catechol-mediated adhesion. HAp provided a biomimetic mineral microenvironment to promote osteogenesis. The optimized GCDH hydrogel exhibited excellent injectability, structural integrity, water confinement, and wet-tissue adhesion. In vitro studies demonstrated that GCDH maintained favorable cytocompatibility and significantly enhanced osteogenic differentiation, including increased alkaline phosphatase activity, matrix mineralization, and osteogenic marker expression. Further in vivo experiments showed that GCDH could accelerate bone regeneration, collagen matrix deposition and osteoblast maturation in rat model with calvarial defect. This work has constructed an orthotopic injectable bone regeneration hydrogel with operational adaptability, interface matching, and regeneration ability, which provides a promising new method for clinical bone defect repair.