Viscoelastic response of contractile filament bundles

TL;DR

This paper presents a theoretical model combining viscoelasticity and active contractility to describe stress fiber dynamics in cells, validated by experimental data and capable of predicting complex mechanical responses.

Contribution

It introduces an analytical model for contractile filament bundles that integrates passive viscoelasticity with active forces, applicable to various boundary conditions.

Findings

Model accurately describes stress fiber contraction after laser surgery.

The complex modulus of a stress fiber can be predicted under cyclic boundary forces.

Good agreement between model predictions and experimental observations.

Abstract

The actin cytoskeleton of adherent tissue cells often condenses into filament bundles contracted by myosin motors, so-called stress fibers, which play a crucial role in the mechanical interaction of cells with their environment. Stress fibers are usually attached to their environment at the endpoints, but possibly also along their whole length. We introduce a theoretical model for such contractile filament bundles which combines passive viscoelasticity with active contractility. The model equations are solved analytically for two different types of boundary conditions. A free boundary corresponds to stress fiber contraction dynamics after laser surgery and results in good agreement with experimental data. Imposing cyclic varying boundary forces allows us to calculate the complex modulus of a single stress fiber.