Vascular Smooth Muscle Precursor Cell Behavior in Non-Uniform Stretch Environments

Abstract

Cells in the body respond to mechanical loads in ways that are crucial to normal and disease physiology. Understanding these processes is difficult due to the complex mechanical environment in vivo. In this research, we have developed several cell-stretching devices capable of subjecting cell cultures to non-uniform stretch distributions in order to investigate pathological responses of vascular smooth muscle cells to physiologic stretches. 10T1/2 cells were cyclically stretched with these devices for 24 hours upon silicone membranes, PDMS tubes, and within 3D PEGDA hydrogels. After stretching, altered cell behaviors were measured, including orientation, proliferation (quantified by BrdU incorporation), and gene expression (quantified by real-time, RT-PCR).

Cells demonstrated marked changes in orientation, proliferation, and mRNA expression, which all varied with cellular location in the non-uniform environment. More specifically, increased orientation, increased proliferation, and more dramatically altered mRNA expression were found in regions of high, uniaxial stretch, relative to regions of low, near-equibiaxial stretch. These findings demonstrate the capabilities of graded stretch distributions to produce graded cell responses, indicating potentially localized smooth muscle cell behavior in a diseased artery. The novel devices employed herein will hopefully improve our understanding of these complicated cellular pathways, ultimately allowing for improved treatment or prevention of vascular disease.