The effect of substrate surface nanotopography on the behavior of multipotnent mesenchymal stromal cells and osteoblasts.

Hexagonally arranged Gold nanoparticles with controllable diameters and inter-particle distances were deposited on thick SiO2 layers on top of Si wafers and used as masks during subsequent reactive ion etching. In this way, arrays of nanopillars are obtained with well-defined diameters (10/30 nm), inter-pillar distances (50-120 nm) and heights (20-35 nm), all on the nanoscale. Such nanotopographies served as substrate for multipotent mesenchymal stromal cells (MSC) and human osteoblasts (OB) allowing to study cellular responses to purely topographically patterned interfaces. Focus was put on adhesion, proliferation and differentiation of the cells. It turned out experimentally that adhesion is comparable for both cell types practically independent of topographical details at the substrate surface. Topography induced proliferation enhancement, however, is again independent of geometrical details in case of MSC, but significantly sensitive to pillar height in case of OB with a clear preference towards short nanopillars (20 nm). A high sensitivity to topographic details is also observed for osteogenic differentiation of MSC, in that case with a preference towards higher nanopillars (50 nm). The present experimental data also allow the important conclusion that cell proliferation and differentiation can be optimized simultaneously by fine-tuning nanoscaled topographical parameters.