The positioning of stress fibers in contractile cells minimizes internal mechanical stress

TL;DR

This paper models the spatial distribution of stress fibers in contractile cells, showing that their arrangement minimizes internal mechanical stress and aligns with experimental observations.

Contribution

It introduces a computational model combining finite element analysis and genetic algorithms to predict stress fiber placement for stress minimization in cells.

Findings

Stress fibers tend to run diagonally across the cell.

Optimized fiber configurations match experimental distributions.

Cells adapt fiber placement to minimize internal stress.

Abstract

The mechanics of animal cells is strongly determined by stress fibers, which are contractile filament bundles that form dynamically in response to extracellular cues. Stress fibers allow the cell to adapt its mechanics to environmental conditions and to protect it from structural damage. While the physical description of single stress fibers is well-developed, much less is known about their spatial distribution on the level of whole cells. Here, we combine a finite element method for one-dimensional fibers embedded in an elastic bulk medium with dynamical rules for stress fiber formation based on genetic algorithms. We postulate that their main goal is to achieve minimal mechanical stress in the bulk material with as few fibers as possible. The fiber positions and configurations resulting from this optimization task alone are in good agreement with those found in experiments where cells in 3D-scaffolds were mechanically strained at one attachment point. For optimized configurations, we find that stress fibers typically run through the cell in a diagonal fashion, similar to reinforcement strategies used for composite material.