Nanosheet-pore topographical titanium substrates: a biophysical regulator of the fate of mesenchymal stem cells

Recent reports have demonstrated that nano- or micro-scale topography could enhance the cellular functions of stem cells. In this study, a sub-micrometer topography composed of nanosheet-pore structures was fabricated on the pure titanium surface by a simple vapor alkaline-treatment method to understand more profoundly sub-micrometer topography mediated stem cell behaviors. The topography was characterized by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, X-ray diffraction and contact angle measurements, respectively. It specifically mediated cellular functions of rat bone marrow-derived mesenchymal stem cells (MSCs) on cellular and molecular levels under either normal medium or osteoinductive medium conditions. The experimental results indicated that the topography dramatically promoted the adhesion of MSCs grown on the surface, but the shape, morphology and spreading of cells were not significantly affected. In addition, the study demonstrated that the formation of focal adhesion complexes (FAs) were highly dependent on the topography, which in turn affects the subsequent biological functions of MSCs, especially accelerating osteogenic differentiation of MSCs under different conditions. Overall, the sub-micrometer topographical titanium substrate was an excellent biophysical regulator of the fate of mesenchymal stem cells, specifically inducing their differentiation into osteoblasts.