Natural and synthetic nanopores directing osteogenic differentiation of human stem cells.

Bone regeneration is a highly orchestrated process crucial for endogenous healing procedures after accidents, infections or tumor therapy. Changes in surface nanotopography are known to directly affect the formation of osteogenic cell types, although no direct linkage to the endogenous nanotopography of bone was described so far. Here we show the presence of pores of 31.93 ± 0.97 nm diameter on the surface of collagen type I fibers, the organic component of bone, and demonstrate these pores to be sufficient to induce osteogenic differentiation of adult human stem cells. We further applied SiO2 nanoparticles thermally cross-linked to a nanocomposite to artificially biomimic 31.93 ± 0.97 nm pores, which likewise led to in vitro production of bone mineral by adult human stem cells. Our findings show an endogenous mechanism of directing osteogenic differentiation of adult stem cells by nanotopological cues and provide a direct application using SiO2 nanocomposites with surface nanotopography biomimicking native bone architecture.