Mechanical response of composite fiber networks subjected to local contractile deformation

Abstract

The extracellular matrix (ECM), forming the cell microenvironment, is a random fiber network whose heterogeneous microstructure serves a vital role in cellular functions such as migration, proliferation, and differentiation. Although prior computational studies used a network of randomly crosslinked fibers for investigating the ECM mechanical response due to the cell contraction, we hereby investigate the cell-induced deformation by considering the interplay between the collagen fibers and soft proteoglycan matrix domain. For this purpose, we represent the complex ECM microstructure by a double network model in which a random network of relatively stiff fibers (representing collagens) is embedded in a homogeneous network (representing the matrix domain). We demonstrate that the interaction between the network of stiff fibers and the network of matrix fibers plays a significant role in the propagation of cell-induced displacements. In particular, as the stiffness of the matrix domain increases, the long-range displacement propagation becomes suppressed. Furthermore, the degree of inhomogeneity in the displacement propagation is controlled by the relative stiffness of fiber and matrix networks. The influence of matrix stiffness becomes prominent for composite networks with random networks having a low average network connectivity and/or composed of fibers with low bending rigidity.