Surface modification is an effective method to resolve the biocompatibility, mechanical, and functional issues of various titanium implant materials. Therefore, many researchers have modified the implant surface to promote the osseointegration of the implant and improve the implant survival rate. In this study, we used photolithography to construct concentric microgrooves with widths of 10 μm and depths of 10 μm, to produce an osteon-mimetic concentric microgrooved titanium surface that was further modified with graphene oxide by silanization (GO-CMS). The modified surface had great biocompatibility and promoted the proliferation of bone marrow-derived mesenchymal stem cells (BMSCs) and RAW264.7 macrophages. The concentric microgrooves on the titanium surface guided cell migration, altered actin cytoskeleton, and caused the cells to arrange in concentric circles. The titanium surface of the GO-modified osteon-mimetic concentric microgrooves promoted the osteogenic differentiation of BMSCs and inhibited the osteoclastogenic differentiation of RAW264.7 cells. Subsequently, we constructed an indirect coculture system and found that RAW264.7 cells cultured on a GO-CMS material surface in a BMSC-conditioned medium (BCM) decreased receptor activator of nuclear factor-κB ligand (RANKL) secretion and increased OPG secretion and also that the BCM inhibited osteoclastogenic differentiation. Additionally, the secretion of OSM increased in BMSCs cultured in RAW264.7-conditioned medium (RCM) in the GO-CMS group, which in turn promoted the osteogenic differentiation of BMSCs. In conclusion, the titanium surface of GO-modified osteon-mimetic concentric microgrooves had dual effects of osteogenesis and antiosteoclastogenesis under single and coculture conditions, which is beneficial for implant osseointegration and is a promising method for the future direction of surface modifications of implants.
Keywords: coculture; graphene oxide; osteoclastogenic differentiation; osteogenic differentiation; osteon-mimetic concentric microgroove.