Nanotopographical Cues Mediate Osteogenesis of Stem Cells on Virus Substrates through BMP-2 Intermediate.

Recent studies have demonstrated rapid osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) on substrates with plant virus modified nanotopographical cues as a promising strategy for bone repair; however, the mechanisms remain unclear. We hypothesized that the highly structurally ordered virus coat proteins, responsible for targeting specific cellular components, are critical for the osteogenesis promotion. In this study, hybrid viral gold nanorods were prepared to explore the effects of highly ordered arranged virus coat proteins on osteogenic differentiation of BMSCs. The results herein indicate that it is the nanotopographical cues modified by structurally ordered virus nanoparticles, not the chemical properties of virus surface, that mediate osteogenesis. Bone morphogenetic protein 2 (BMP-2) expression is significantly increased and serves as a modulator that mediates the osteogenic differentiation in response to the viral particle coatings. After BMP-2 is inhibited by Noggin, the osteogenesis promoting effects are significantly compromised, demonstrated by lower alkaline phosphatase activity and calcium sequestration. This study reveals that plant virus modified nanotopographical substrates promote osteogenic differentiation of BMSCs through increasing BMP-2 autocrine. It provides key insights to engineering functional materials for rapid bone repair.