3D-printed oxygen-releasing scaffolds promote bone repair via angiogenesis and osteogenesis

The treatment of large bone defects is rendered challenging owing to ischemia, hypoxia, and insufficient osteogenesis in the defect sites. Consequently, the use of oxygen-releasing osteogenic materials has been studied extensively in recent years. This study aimed to construct and test a 3D-printed composite scaffold with both angiogenic and bone-repair functions. A “sandwich”-like structure containing polycaprolactone, hydroxyapatite, and calcium peroxide was fabricated using fused deposition modeling 3D printing technology. The polycaprolactone/hydroxyapatite/calcium peroxide composite scaffolds exhibited excellent mechanical properties and sustained oxygen release for over three weeks. Compared to the control groups, the polycaprolactone/hydroxyapatite/calcium peroxide scaffolds also significantly promoted rat bone marrow mesenchymal stem cell proliferation, migration, adhesion, and osteogenic differentiation, with the scaffold containing 1% calcium peroxide showing the most potent pro-angiogenic and bone-repairing effects. In a rat calvarial defect model, radiographic and histological analyses revealed that the synergistic effects of calcium peroxide and hydroxyapatite significantly induced vascular network formation, accelerated bone regeneration across the entire defect area, and markedly enhanced new bone formation. In summary, this work proposes a novel strategy for fabricating cell- and growth factor-free bone tissue engineering scaffolds with potential for tissue regeneration and clinical replacement.