Tensile Properties of Smooth Muscle Cells, Elastin, and Collagen Fibers

Abstract

Artery walls change their dimensions as well as mechanical properties adaptively in response to mechanical stimulation. Because these responses are caused by the vascular smooth muscle cells (VSMCs) in the media, detailed understanding of the mechanical environment of the VSMCs is indispensable to know the mechanism of the adaptation. Artery wall has been often assumed to be homogenous in conventional mechanical analyses from macroscopic viewpoint. At a microscopic level, however, it is highly heterogeneous, and conventional mechanical analyses using homogeneous models are far from satisfactory to estimate the mechanical environment of the VSMCs. Thus, the mechanical properties of each element composing the artery wall, i.e., VSMCs, elastin, and collagen fibers, should be measured directly. In this chapter, we first introduce the experimental techniques used for the tensile testing of tissues and cell at a microscopic scale and review the tensile properties of VSMCs in detail, and then, those of elastin and collagen fibers. In contrast to elastin and collagen fibers that are simple passive materials, VSMCs are alive and their mechanical properties are highly complicated. Their mechanical properties are reviewed from the viewpoints of smooth muscle contraction, anisotropy in cytoskeletal structure, and viscoelasticity.