Three-Dimensional Printed BGS Treat a Large Bone Defect in a Rabbit Model

This study aimed to evaluate if the 3D printed bioactive glass porous scaffolds (BGS) can improve the reconstruction of the large bone defect. A rabbit model of large bone defects was established by making a 1.0 or 1.5 cm segmental defect in the middle of the femur bone. Then a 1.0 or 1.5 cm BGS was implanted into the bone defect. X-ray imaging showed that in both 1.0 and 1.5 cm groups, the newly formed bone tissue could be observed at 4 weeks after implantation, but a strengthened ossification trend could be observed at different time points. In the 1.0 cm group, a larger number of newly formed bone tissues were observed at 4 weeks, and in the 1.5 group, more newly formed bone tissues were found at 8 weeks. Nevertheless, ossified tissue generation on the BGS mainly completed at 12 weeks after implantation in both groups. The H&E staining revealed that the 3D BGS was easily degraded to form osteoid-like material in vivo , where the neo-ossification gradually occurred from the edge to the center. Immunohistochemical analysis showed that in the 1.0 group, protein expressions of three osteogenesis-related genes- BMP, collagen I and RUNX-2-all peaked at 8 weeks, and then gradually decreased at 12 and 18 weeks. In the 1.5 group, BMP and collagen I peaked at 18 weeks.