Injectable mineralized hydrogel microspheres for accelerated osteocyte network reconstruction and intelligent bone regeneration

The disruption and limited reconstruction capacity of the osteocyte network are pivotal factors underlying impaired bone regeneration. This study developed an injectable mineralized hydrogel microsphere that provides a mineral-rich environment and optimal matrix stiffness for osteocyte network restoration. Furthermore, it spatially activates Notch signaling through osteocyte-derived vesicles with high Jagged1 expression, promoting osteocyte differentiation and enhancing angiogenic regulatory function. Specifically, hydrogel microspheres combining gelatin methacrylate (GelMA), alginate methacrylate (AlgMA), and osteocyte membrane vesicles (OMVs) were fabricated via gas-shear microfluidics and photopolymerization, followed by in situ pre- mineralization to produce mineralized microspheres. Findings indicate that mineralized hydrogel micro- spheres exhibit significantly increased compressive modulus and in situ formation of amorphous calcium phosphate particles within the gel matrix. In vitro, the mineralized microspheres effectively facilitated osteogenic differentiation in bone marrow-derived mesenchymal stem cells (BMSCs), with adherent cells displaying accelerated osteocyte marker expression. Co-culture experiments further revealed enhanced vascular formation potential. Ectopic bone regeneration studies demonstrated that mineralized hydrogel microspheres promote rapid formation of mature osteocyte networks in vivo. Moreover, in a femoral critical bone defect model, these microspheres accelerated defect healing. Collectively, mineralized hydrogel microspheres expedite osteocyte network reconstruction, supporting intelligent bone regeneration, and present a promising approach for critical- sized bone defect repair.