A critical stress model for cell motility.

Area of Science:

• Biophysics
• Cell Biology
• Theoretical Biology

Background:

• Amoeboid cell movement is crucial for biological processes but its mechanics are complex.
• Existing viscoelastic models often describe steady-state motion, not dynamic locomotion.
• Understanding cell-substrate interactions is key to deciphering cell migration.

Purpose of the Study:

• To develop a theoretical model integrating viscoelasticity and active stress for ameboid cell locomotion.
• To describe the step-by-step "walking" mechanism of cells, including protrusion and tail detachment.
• To analyze cell length variations and velocity dynamics during movement.

Main Methods:

• Development of a theoretical model combining continuum viscoelasticity with dynamic active stress.
• Simulation of cell movement involving protrusion, adhesion, and tail detachment phases.
• Analysis of stress dynamics within the cell and at the cell-substrate interface.

Main Results:

• The model accurately describes a "walking" motion distinct from steady-state movement.
• Cell length initially increases then stabilizes as movement progresses.
• A critical stress value for tail detachment was identified and estimated.

Conclusions:

• The dynamic active stress model provides a more realistic framework for ameboid cell movement.
• The findings elucidate the mechanical basis of cell locomotion and adaptation.
• The estimated critical stress offers a quantifiable parameter for cell-substrate interactions.