Heterogeneous Force Chains in Cellularized Biopolymer Network

TL;DR

This study models the mechanical response of biopolymer networks to cell contraction, revealing that force chains enable long-range force transmission and mechanical signaling between cells.

Contribution

It introduces a graph-based model to analyze force chains in biopolymer networks, highlighting their heterogeneity and role in long-range force transmission.

Findings

Force chains carry most of the network forces.

Force chains are aligned fibers or reoriented by contraction.

Force decay along chains is slower than radially averaged forces.

Abstract

Biopolymer Networks play an important role in coordinating and regulating collective cellular dynamics via a number of signaling pathways. Here, we investigate the mechanical response of a model biopolymer network due to the active contraction of embedded cells. Specifically, a graph (bond-node) model derived from confocal microscopy data is used to represent the network microstructure, and cell contraction is modeled by applying correlated displacements at specific nodes, representing the focal adhesion sites. A force-based stochastic relaxation method is employed to obtain force-balanced network under cell contraction. We find that the majority of the forces are carried by a small number of heterogeneous force chains emitted from the contracting cells. The force chains consist of fiber segments that either possess a high degree of alignment before cell contraction or are aligned due to the reorientation induced by cell contraction. Large fluctuations of the forces along different force chains are observed. Importantly, the decay of the forces along the force chains is significantly slower than the decay of radially averaged forces in the system. These results suggest that the fibrous nature of biopolymer network structure can support long-range force transmission and thus, long-range mechanical signaling between cells.