Simultaneously improved physicochemical characterization, in-vitro osteogenesis and angiogenesis in porous hydroxyapatite composite scaffolds through tailoring 45S5 bioglass content

This study aimed to develop 45S5 bioglass/hydroxyapatite (BG/HA) composite scaffolds with high porosity, excellent biodegradability, and osteoblast responsiveness for bone defect repair. The scaffolds containing 0, 10, 20, 30, and 40 wt% BG were fabricated using a combination of space-holder, cold pressing and spark plasma sintering techniques. Physicochemical characterization, mechanical properties, and in vitro osteogenic and angiogenic potentials were systematically investigated. The results showed that, compared to HA scaffolds, the composite scaffolds exhibited an increase in porosity from 67% to 75% and macropore (>300 μm) content from 40% to 74%. When the scaffold containing 30 wt.% BG outperformed the others while maintaining adequate mechanical strength. And its 12-week degradation rate was 26.48% versus 5.90% for the HA scaffold. Moreover, the weight gain of the scaffold due to apatite formation increased by approximately 7.89-fold after a 7-day immersion period. In vitro, BG supplementation made cell viability exceed 83% and enhanced the adhesion of MC3T3 cells ( p<0.05 ). Additionally, BG promoted osteogenic differentiation, evidenced by higher expression of osteoblast-specific genes and proteins (Runx2, Col I, OPN and OCN), increased alkaline phosphatase activity and elevated calcium mineralization levels ( p  < 0.0001). Furthermore, angiogenesis-related parameters were more desirable in the composite scaffold group. Fundamentally, these effects primarily result from BG altering the physicochemical properties, which modulates the release of bioactive ions, including silicon, calcium and phosphate, thereby driving cellular responses through cascade reactions. These findings suggest that BG/HA composite scaffolds possess consistent high porosity and superior biochemical characteristics, demonstrating significant potential for clinical development and application.