Ga-containing Ti alloy with improved osseointegration for bone regeneration: In vitro and in vivo studies

Ti and Ti alloys are widely used implant materials in clinical orthopedics because of their excellent mechanical properties, wear resistance, and biocompatibility. However, the therapeutic effect of Ti alloys is limited by their poor osseointegration. Thus, this study aimed to improve the poor osteointegration of Ti by fabricating Ti alloys containing different amounts of Ga. The properties, including element distribution, hardness, and calcium salt deposition of the Ti–Ga alloys were evaluated. Results showed that Ga, as a bioactive metal, promoted apatite formation. The osteogenic performance of the Ti–Ga alloys was evaluated in vitro and in vivo using rat bone marrow mesenchymal stem cells (BMSCs) and a rat intramedullary nail model, respectively. Biological results demonstrated that the Ti–Ga alloys provided suitable conditions for cell adhesion and spreading, promoted the osteogenic differentiation of BMSCs, and enhanced osseointegration in vivo better than pure Ti. Transcriptomic results further indicated that Ga enhanced osseointegration by downregulating gremlin expression. This study introduced Ti–Ga alloys as promising implant materials with better osseointegration than pure Ti and elucidated the possible mechanism by which Ga promotes osteogenesis.