A cell-laden methacrylated chitosan-based photocrosslinkable hydrogel for bone tissue engineering and its in vitro structural and biological characterization

The treatment of extensive bone defects involves the use of multicomponent scaffolds where different components can be precisely controlled according to specific conditions. Therefore, hybridizing biomaterials within cell-laden osteogenic bioscaffolds provides promising opportunities for clinical applications. In this study, a cell-laden, photocrosslinkable hydrogels composed of methacrylated chitosan (MECs) and silk fibroin (SF) fibers was developed to induce osteogenesis, and its structural and biological properties was investigated. SF fibers were mineralized with a hydroxyapatite (HAp) layer using a modified alternate soaking followed by heat treatment. Optimal photocrosslinking conditions were determined using the Taguchi method. SF fibers were incorporated into MECs at varying concentrations, and the resulting hydrogel structure was assessed with and without fibers under different ionic conditions. Adipose-derived stem cells (ADSCs) were encapsulated into hydrogels, and their morphology, viability, and osteogenic gene expression were analyzed. FTIR, XRD, and SEM confirmed successful mineralization of SF, with heat treatment enhancing HAp crystallinity. SF addition effectively prevented hydrogel shrinkage and promoted a porous structure due to fiber enrichment and double crosslinking. Encapsulated ADSCs remained viable after 14 days, and mineralized fibers significantly upregulated bone-related gene expression compared to controls. This study introduces a biomimetic, fiber-enriched, osteoinductive hydrogel with strong potential for the repair and regeneration of large bone defects.