Gyroid-Structured Scaffolds Guide Uniform Ossification and Modulate Vascular Morphology During Rat Calvarial Bone Defect Regeneration.

Bone repair procedures rely on osteoconductive material scaffolds that guide and promote bone ingrowth through their architecture. This study investigated how the bone formation and vascularization are modulated within gyroid macroporous scaffolds during the regeneration of rat calvarial bone defects. It compared scaffold-guided regeneration to spontaneous healing through 3D analysis of both ossification and vascularization. Two disc-shaped bioceramic scaffolds with either wide or narrow porous geometries were designed and fabricated to facilitate or limit bone ingrowth. While overall ossification dynamics were similar regardless of repair efficacy, scaffold presence modulated the ossification pattern, promoting bone formation throughout by conduction. The scaffolds also influenced vascular network morphology but not its density. Notably, 3D imaging revealed a negative correlation between vascularization and bone formation in scaffold-filled defects, while no correlation was found in empty defects. This result suggests that ossification during calvarial regeneration relies on additional pro-osteogenic factors beyond robust vascularization. These insights are valuable for optimizing scaffold-based strategies to enhance bone regeneration in calvarial defects.