The influence of substrate stiffness on osteogenesis of vascular smooth muscle cells

Vascular stiffening occurs with advanced age and under pathological conditions such as vascular calcification, during which the osteogenesis of smooth muscle cells (SMCs) plays a key role. However, whether the stiffness of cellular microenvironment influences osteogenic responses in vascular SMCs is not well understood. Here, we cultured SMCs on the poly(dimethylsiloxane) (PDMS) substrates with varying stiffness from 0.363 to 2.327 MPa. The cell osteogenic transdifferentiation was induced by β-glycerophosphate. Our findings demonstrated that the extent of osteogenesis in SMCs varied with the substrate stiffness. On three substrate stiffness, cells on the intermediate one (0.909 MPa) showed the highest extent of the osteogenesis based on the expression of osteogenic markers and calcium deposition. Transforming growth factor-β1 and autophagy were involved in this stiffness-dependent process. This work highlights the importance of substrate stiffness to the osteogenesis of vascular SMCs, giving new scientific information for understanding of SMCs-mediated vascular calcification and designing of vascular implants.