In vivo evaluation of porous lithium-doped hydroxyapatite scaffolds for the treatment of bone defect

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.