mTORC2 regulates hierarchical micro/nano topography-induced osteogenic differentiation via promoting cell adhesion and cytoskeletal polymerization

Surface topography acts as an irreplaceable role in the long-term success of intraosseous implants. In this study, we prepared the hierarchical micro/nano topography using selective laser melting combined with alkali heat treatment (SLM-AHT) and explored the underlying mechanism of SLM-AHT surface-elicited osteogenesis. Our results show that cells cultured on SLM-AHT surface possess the largest number of mature FAs and exhibit a cytoskeleton reorganization compared with control groups. SLM-AHT surface could also significantly upregulate the expression of the cell adhesion-related molecule p-FAK, the osteogenic differentiation-related molecules RUNX2 and OCN as well as the mTORC2 signalling pathway key molecule Rictor. Notably, after the knocked-down of Rictor, there were no longer significant differences in the gene expression levels of the cell adhesion-related molecules and osteogenic differentiation-related molecules among the three titanium surfaces, and the cells on SLM-AHT surface failed to trigger cytoskeleton reorganization. In conclusion, the results suggest that mTORC2 can regulate the hierarchical micro/nano topography-mediated osteogenesis via cell adhesion and cytoskeletal reorganization.