Control of Extracellular Matrix Organization through Coupled Mechanical and Chemical Inputs

Abstract

The extracellular matrix (ECM) is a critical cellular component that provide structural support and organization as well being linked to a variety of cell responses including motility, proliferation, and apoptosis. Fibronectin (FN) is an ECM protein that is secreted by many mammalian cells as a soluble dimer and assembles into insoluble multimeric fibrils at the cell surface. This specific extracellular component has been linked to wound healing, cell adhesion, blood coagulation, cell differentiation and migration, maintenance of the cellular cytoskeleton, and tumor metastasis. In addition, FN is constantly subjected to mechanical and chemical stimulations, resulting in a highly dynamic microenvironment that is constantly being remodeled by the cell. While many studies have examined FN organization through various modes of chemical stimulation, there is limited work on examining the effects of mechanical stimulation or in examining the coupled affects of mechanical and chemical stimulation. In our present study we used a custom fabricated device to probe the effects of mechanical and chemical stimulation on FN organization. We exposed single cells to equibiaxial stretching and observed an increase in localized FN fibrils relative to unstimulated cells. The response patterns of the FN were markedly distinct when examining intracellular versus extracellular organization. We also perturbed this system by coupling the mechanical stimulation with chemical stimulation by exposing cells to equibiaxial stretching while inhibiting Rho activity. These dual mode stimulated cells revealed similar responses to cells exposed to mechanical stimulation in that increased FN fibrils was observed, indicating mechanics may play more of a dominate role in ECM organization with respect to Rho activity. These results have implications in a variety of fields including biophysics, cell mechanics, and mechanotransduction.