Silver nanoparticles stimulate osteogenesis of human mesenchymal stem cells through activation of autophagy.

Aim: Previously, different results have been achieved regarding effects of silver nanoparticles (Ag NPs) on osteogenesis of stem cells and the mechanisms have not been disclosed yet, which are quite important for potential application of Ag NPs in bone reconstruction. Materials & methods: Effects of Ag NPs on osteogenesis of human mesenchymal stem cells (hMSCs) with underlying mechanisms were investigated. Results: Ag NPs at 2.5 and 5 mu g/ml increased osteogenic proteins expression and mineralization of hMSCs. Meanwhile, autophagy was activated by Ag NPs and it could be inhibited by 3-methyladenine. Furthermore, osteogenesis induced by Ag NPs could also be reversed by 3-methyladenine. Conclusion: These findings suggest that autophagy is involved in stimulating osteogenesis of hMSCs induced by Ag NPs. Graphical abstract