Hydrodynamic instabilities, waves and turbulence in spreading epithelia

Area of Science:

• * Biophysics
• * Cell Biology
• * Fluid Dynamics

Background:

• * Epithelial monolayers exhibit complex dynamics, often appearing elastic.
• * Collective cell migration involves active contractility and substrate interactions.
• * Understanding these dynamics is crucial for tissue development and repair.

Purpose of the Study:

• * To develop a hydrodynamic model for spreading epithelial monolayers.
• * To investigate the role of active contractility and traction in cell dynamics.
• * To explain observed phenomena like plithotaxis and nonlinear wave propagation.

Main Methods:

• * Modeled epithelial monolayers as polar viscous fluids.
• * Incorporated active contractility and substrate traction forces.
• * Analyzed nonlinear wave regimes and mapped to the complex Ginzburg-Landau equation.

Main Results:

• * Active forces generate an instability leading to nonlinear traveling waves.
• * Wave propagation depends on polarity and contact forces, with characteristic timescales.
• * Model explains plithotaxis via flow-polarity coupling and quantifies force transmission non-locality.
• * Predicted transitions to weak turbulence and chaotic dynamics.

Conclusions:

• * The viscous fluid model accurately describes epithelial monolayer dynamics, challenging elastic interpretations.
• * The model offers testable predictions for the non-elastic nature of mechanical waves.
• * Provides insights into collective cell behaviors and nonlinear dynamics, including turbulence.