Slow stress propagation in adherent cells

Area of Science:

• Cell Biology
• Biophysics
• Mechanobiology

Background:

• Cellular mechanical cues regulate critical behaviors like motility and differentiation.
• While local mechanosensors are known, understanding stress propagation across cells is crucial for spatial coordination.
• Previous models often fail to capture the full picture of cellular mechanical responses.

Purpose of the Study:

• To quantify the magnitude and timing of intracellular stress propagation within cells.
• To investigate how mechanical perturbations spread from a local point across the cell.
• To explore the underlying mechanisms and models governing this stress propagation.

Main Methods:

• Utilized atomic force microscopy (AFM) for local cell surface indentation.
• Employed particle tracking by defocused fluorescence microscopy to measure 3D displacements.
• Tracked integrin-bound fluorescent particles to monitor stress transmission.

Main Results:

• Observed immediate cellular response followed by slower equilibration of mechanical stress.
• Demonstrated that equilibration time increases with distance from the initial perturbation.
• Found that disrupting the actin cytoskeleton eliminates this distance-dependent equilibration.
• Experimental data aligns with poroelastic models, not traditional viscoelastic ones.

Conclusions:

• Mechanical stress propagates slowly and dissipatively across adherent cells in a distance-dependent manner.
• The actin cytoskeleton plays a critical role in this stress propagation mechanism.
• Poroelastic models provide a better framework for understanding cell mechanics under perturbation than traditional models.