Many physiological processes depend on the response of biological cells to mechanical forces generated by the contractile activity of the cell or by external stresses. Using a simple theoretical model that includes the forces due to both the mechanosensitivity of cells and the elasticity of the matrix, we predict the dynamics and orientation of cells in both the absence and presence of applied stresses. The model predicts many features observed in measurements of cellular forces and orientation including the increase with time of the cellular forces in the absence of applied stress and the consequent decrease of the force in the presence of quasi-static stresses. We also explain the puzzling observation of parallel alignment of cells for static and quasi-static stresses and of nearly perpendicular alignment for dynamically varying stresses. In addition, we predict the response of the cellular orientation to a sinusoidally varying applied stress as a function of frequency.
Bibliographical noteFunding Information:
We are grateful for discussions with A. Buguin, M. E. Fisher, N. Gov, S. Jungbauer, R. Kemkemer, B. Ladoux, A. Nicolas, J. Prost, U. Schwarz and P. Silberzan and for support from the Israel Science Foundation and an EU Network Grant. This research was made possible in part by the historic generosity of the Harold Perlman Family. Correspondence and requests for materials should be addressed to S.A.S.