Light-Curable Methacrylated Carboxymethyl Chitosan Hydrogel Incorporating Bone Morphogenic Protein-2-Immobilized Bioactive Glass for Spinal Bone Regeneration

Bioactive glass (BG) has emerged as a promising material for bone tissue engineering due to its ability to release osteogenic ions and establish robust interfaces with living tissues, thereby contributing to spinal bone regeneration by facilitating osteointegration and structural stability. Despite these advantageous properties, reconstructing spinal bone defects remains particularly challenging because BG is typically available in powder form, which lacks sufficient mechanical strength and is difficult to handle surgically, especially given the substantial mechanical demands of the spinal column. To overcome these limitations, we employed an injectable, light-curable methacrylated carboxymethyl chitosan (CMCSMA) hydrogel to enable minimally invasive delivery and precise defect filling. Furthermore, to complement BG's strong osteoconductive capacity with osteoinductive functionality, bone morphogenetic protein-2 (BMP-2) was immobilized onto BG particles (BG/BMP-2), creating a composite scaffold with dual biological activity. The BG/BMP-2/hydrogel system demonstrated sustained BMP-2 release, enhanced osteogenesis, and substantial new bone formation, underscoring the synergy between BG's bioactive ion release and hydroxyapatite-forming ability. The photocurable hydrogel matrix provided conformal adaptation to defect geometry, potentially improving surgical outcomes. Collectively, this composite represents a promising strategy for minimally invasive and mechanically resilient spinal bone regeneration.