Finite Element Model of a Cultured Vascular Smooth Muscle Cell Subjected to Uniaxial Stretch: Effect of Orientation Angle of Stress Fibers on Biomechanical Responses

Abstract

Vascular smooth muscle cells (SMCs) in the extracellular matrix adapt to their surrounding environment in vivo with its contraction and relaxation. As blood pressure increases, the circumferential stress on the aortic wall also increases. The major components of the media are SMCs, so SMCs should regulate the vessel diameter and the mechanical balance of the aortic medial ring. Thus, it is important to clarify how external forces on SMCs are transmitted through the intracellular components. Nuclei may sense changes in the applied mechanical stretch via stress fibers (SFs) or focal adhesions (FAs). However, there is little quantitative information available about the mechanical contribution of SFs and FAs to whole-cell mechanical events such as uniaxial stretching. In the present study, therefore, we developed a finite element model of a cultured SMC, with contractile SFs, on a silicone substrate, and applied a uniaxial stretch, to investigate the mechanotransduction pathways involved in SMCs. We revealed that the initial orientation angle of the SFs was closely correlated with their resultant stretch, and the magnitude of the biomechanical force exerted by SFs.