Adhesion, Viability and Differentiation of Adipose Tissue Derived Mesenchymal Stem Cells onto Micro/Nanostructured Polystyrene Substrates

Mesenchymal stem cells exhibit unique properties such as self-renewal and differentiation into different types of cells. To study in vitro these properties, micro/nanostructured surfaces that mimic the morphology of in vivo extracellular environment have been employed as substrates for stem cells culture and differentiation. In this work, micro/nanostrutured polystyrene surfaces fabricated through oxygen plasma etching were used to study the topography effect on adhesion, viability and differentiation of mesenchymal stem cells derived from rat adipose tissue (rMSCs). For this purpose, rMSCs were cultured on micro/nanostructured surfaces with average peak-to-valley height ranging from 50 to 500 nm, for 14 and 21 days, with either standard culture or osteogenic differentiation medium. Regarding cells cultured with standard medium, it was found that both their viability and morphology was negatively affected when cultured to micro/nanostructured surfaces with average peak-to-valley height ≥270 nm, while mineralization, as determined by Alizarin Red S staining, was slightly increased on the micro/nanostrutured surfaces compared to flat ones, indicating that micro/nanotopography did not affect osteogenic differentiation. On the other hand, when rMSCs were cultured with osteogenic differentiation medium on micro/nanostrutured surfaces, their viability and morphology were strongly affected, and a 30% reduction in mineralization compared to flat polystyrene was determined on surfaces with average peak-to-valley structures ranging between 90 and 480 nm. On the contrary, when cells were cultured with osteogenic differentiation medium on surfaces with peak-to-valley structures of 50 nm, mineralization was 1.7 times higher compared to flat surfaces. These results indicate that surface roughness ≥90 nm has a strong negative effect on viability, morphology and mineralization of rMSCs cultured in both media, while surface roughness of 50 nm exhibits a ~70% increase in mineralization of rMSCs compared to flat substrates when cultured in osteogenic medium. Thus, micro/nanotopography could be a useful tool to promote MSCs differentiation in vitro.