Bioactive SiO2@Ru nanoparticles for osteogenic differentiation of mesenchymal stem cells via activation of Akt signaling pathways.

The surface chemistry of materials has an interactive influence on cell behavior. It is now well established that surface chemistry can affect cell adhesion, proliferation, and differentiation. Although amino (NH2)-terminated surfaces generated by the modification of nanoparticles with silane can promote osteogenic differentiation of mesenchymal stem cells (MSCs), how silica surfaces with ruthenium nanoparticles (SiO2@Ru) act on MSCs remains largely unknown. A concentration of 5 μg mL-1 aminopropyltriethoxysilane (APTS)-modified SiO2 nanoparticles (SiO2-NH2) or SiO2@Ru was nontoxic to MSCs, based on MTT and apoptosis assays. In addition, SiO2-NH2 and SiO2@Ru did not affect the surface phenotype or morphology of MSCs. SiO2@Ru can be used to trigger the differentiation of MSCs into osteocytes, minimising the need for exogenous biological supplementation. TEM images revealed that SiO2@Ru might interact with proteins located in the cytoplasm, which would have a further impact on subsequent cellular signaling pathways. Activation of Akt signaling pathways was observed in MSCs cultured with SiO2@Ru and these enhancement effects could be blocked by the Akt inhibitor LY294002. SiO2@Ru exhibited in vitro osteocompatibility that surpassed that of SiO2-NH2, as well as supporting the proliferation and differentiation of MSCs. This demonstrates the potential of SiO2@Ru for use in bone regeneration.