Abstract: Hydroxyapatite (HA) is a representative bone repairing biomaterial for its similar composition to human bones and teeth. However, pure HA is limited in application for some unwanted characteristic, such as it is brickle and weakness in degradation. In this study, we modified HA by doping magnesium (Mg) to the material and studied its property in vitro. Besides, we also evaluated the calvarial defect repair effect using MgHA combined with rhBMP-2 in goat model. According to our outcomes, HA composited Mg made the scaffold smooth and the pore regular. In vitro study, Mg could increase the Ca releasing, which may reflect…a faster degradation property modified by Mg. And then, MgHA improved the cell viability and proliferation. Furthermore, MgHA could increase the expression of ALP, Collagen I and VEGF protein compared with pure HA (p < 0.5 , respectively). In the vivo study, MgHA showed a better bone defect healing effect in computed tomography (CT) evaluation compared with HA (p < 0.05 ), but it was inferior to the MgHA/rhBMP-2 (p < 0.05 ). Besides, in the histological analysis, MgHA/rhBMP-2 showed the most effective bone formation outcome (p < 0.05 ), and the MgHA group was significant better than the pure HA group on osteogenesis (p < 0.05 ). Furthermore, Collagen I and VEGF mRNA expression at 12 week in MgHA/rhBMP-2 group were also significat higher than other two groups. In conclusion, Mg had effects on bone formation and angiogenesis, and MgHA/rhBMP-2 had improved the bone defect repair effect. It is worthy of being recommended to bone tissue engineering.
Keywords: Bone defect repair, magnesium, hydroxyapatite, recombinant human bone morphogenetic protein-2
Abstract: Hydroxyapatite (HA) possesses similar mineral components to bone and possesses good physicochemical properties. Even though pure HA scaffold is brittle, it is insufficient in promoting vascularization and osteoinductivity. This study was conducted to assess whether lithium (Li) incorporated into HA could improve the scaffolds’ inherent shortcomings. In the experiments, Li-hydroxyapatite scaffolds’ mechanical strength, biocompatibility, and biodegradability were researched primarily. In vivo studies, the Li hydroxyapatite scaffolds were implanted into an animal model to repair the bone defects. Meanwhile, we also evaluated the expression of angiogenic and osteogenic factors. For comparison, autologous bone, hydroxyapatite, and blank control groups were designed. According…to the results, Li incorporated with hydroxyapatite did not significantly change the scaffold’s degradation velocity, but it obtained higher compress mechanical strength. After Li was doped, bone regeneration was further enhanced but the angiogenic effect was not improved significantly. The in vivo study, Li-HA scaffolds improved new bone formation with GSK-3𝛽 decreased and 𝛽-catenin increased. In conclusion, doped Li into hydroxyapatite was an alternative strategy for improving hydroxyapatite’s mechanical property and promoting the osteogenesis potential. This method is highly recommended for clinical application based on this study alone.
Keywords: Scaffold, hydroxyapatite, lithium, bone defect repair