Effect of Tensile Stress on Smooth Muscle Cells

Abstract

Cellular responses to mechanical stresses play an important role in the physiology of many cell types in healthy and diseased states. In vascular smooth muscle cells (VSMC), as in any other cells anchored to extracellular matrix, external mechanical stresses are imposed on a preexisting force equilibrium generated by the cytoskeletal tension. The ability to measure real-time mechanosensitive events at sub-cellular level in response to discrete and physiologically relevant mechanical stimulation is the critical component in understanding mechanically-induced cellular remodeling. Mechanical perturbation of a VSMC by the atomic force microscope (AFM) tip mimics the tensile stress in the vessel wall. By integrating tensile stress stimulation with simultaneous optical imaging using total internal reflection fluorescence and fast spinning-disk confocal microscopy, we have the unique opportunity of investigating in real-time the mechanically-induced cross-talk between apical and basal cell surface. Thus, we were able to measure vinculin and actin recruitment at focal adhesions upon tensile stress stimulation, and stress fibers bundling and reassembly. Understanding the real-time contractile and adhesion events associated with live VSMC response to force, provides fundamental new information regarding the coordinated cellular responses involved in VSMC adaptation to the local extracellular environment in the vessel wall.