Spatiotemporally-graded BHP/G@met scaffold system enables sequential angiogenesis-osteogenesis coupling for accelerated bone regeneration

Addressing the clinical challenge of spatiotemporal coordination between vascularization and osteogenesis in bone repair, this study develops a composite scaffold system integrating piezoelectric stimulation and controlled drug release to achieve sequential regulation of angiogenesis-osteogenesis coupling. Combining piezoelectric barium titanate/nano-hydroxyapatite/polycaprolactone (BTO/nHA/PCL, BHP) with metformin (Met)-loaded GelMA (G@Met) hydrogels, the BHP/G@Met scaffolds are fabricated through dual-nozzle 3D printing. Material characterization confirms hierarchical porosity, stable piezoelectric output under ultrasound (US), and sustained drug release kinetics aligned with early-phase vascularization requirements. In vitro co-culture models demonstrate enhanced endothelial cell migration and tubular network formation during the initial 7d phase, followed by potent osteogenic differentiation of mesenchymal stem cells at intermediate (14d) and terminal (21d) periods. Dual-animal models reveal superior bone regeneration with extensive neovascularization and osseous tissue infiltration. Transcriptome sequencing and network pharmacological analyses identify PI3K-AKT signaling as the central pathway for BHP/G@Met coordinating sequential angiogenesis-osteogenesis. By synergizing piezoelectric bioelectrical cues with spatiotemporal drug delivery, BHP/G@Met pioneers a chronologically adaptive strategy to match the spatial-temporal bone healing microenvironments, offering a paradigm for dynamic tissue regeneration.