Osteogenic differentiation of murine mesenchymal stem cells by combination of surface topography and uniaxial stress

Recent research has shown that enhanced focal adhesion between cells and extracellular matrix (ECM) and intracellular actin polymerization can accelerate cellular functions like proliferation and differentiation. It is a desirable and necessary technique to modulate cellular functions in the desired lineage in tissue engineering. Previously, we have shown that topographical effects of micropatterns on a cell culture substrate promoted osteogenic differentiation of mesenchymal stem cells (MSCs) without administration of osteogenic growth factors. In this study, bone marrow mesenchymal stem cells from rats were cultured with combined biophysical stimuli, such as surface topography of biomaterials and uniaxial tensile stress and induced osteogenic differentiation. We evaluated MSCs by assessment of alkaline phosphatase (ALP). We demonstrated that a polydimethylsiloxane substrate with microgroove patterns (2 μm of ridge thickness, 1 μm of depth and 1 μm of groove distance) could suppress osteogenic differentiation compared to a flat substrate. Changes of cell adhesion and shape were observed at microgroove substrates by immunofluorescence staining of focal adhesion and actin filaments. We showed that to apply the stretching force promoted differentiation at microgroove substrates but inhibited differentiation at the flat surface. Through this study, a more efficient method to control cellular fate is expected to be established for tissue regeneration in vitro.