Strain-Induced Anisotropy Increases the Range of Force Transmission in Fibrous Networks

Background: Cells exert forces on their environment, causing local deformations of the extra-cellular matrix (ECM). The ECM consists of cross-linked polymer chains, also called semi flexible fibers. Characterizing the response of the ECM to these forces is important for understanding many biological processes at the cell level and at the tissue level. It has been well established that multiple nonlinear phenomena play a role in propagating cell forces, but a theory to determine the contribution of the various non-linear effects and unify them into a more general mechanism is absent.

Methods: In this study, we performed finite-element simulations to obtain displacement decay rates in fiber networks containing a contracting cell, and uniaxial tensions simulations for measuring the elastic response in both longitudinal and transversal directions.

Results: We observe that the displacement decay is slower than in continuous elastic-isotropic media. We quantify the contribution of three mechanisms - fiber alignment, fiber stiffening and fiber buckling, to slow down the decay rates.

Conclusion: We conclude that all three mechanisms contribute to a more general phenomenon – strain induced elastic anisotropy, which is the key property controlling the decay of displacements.