Turbulent Dynamics of Epithelial Cell Cultures

Area of Science:

• Cell biology
• Soft matter physics
• Biophysics

Background:

• In vitro human bronchial epithelial cell (HBEC) cultures display complex collective behaviors.
• Understanding cellular rearrangements and flow dynamics is crucial for tissue development and disease modeling.

Purpose of the Study:

• To investigate the collective flows and structural rearrangements in HBEC cultures.
• To characterize the dynamics of vortices and nematic domains formed by HBECs.
• To compare experimental findings with theories of active nematic suspensions.

Main Methods:

• Analysis of large populations of vortices in HBEC cultures.
• Characterization of vortex area distribution and rotational frequency.
• Identification and analysis of nematic domains and defects.
• Comparison of observed velocity fields with hydrodynamic theories.

Main Results:

• Activity-driven collective flows generate spatially random vortex ensembles.
• Vortex area follows an exponential law with a constant mean, and rotational frequency is size-independent.
• HBECs self-organize into nematic domains, with defects at domain interfaces.
• Defect dynamics show a constant total number due to balanced nucleation and annihilation.
• Velocity fields near defects are accurately described by extensile active nematic theory.

Conclusions:

• HBEC cultures exhibit characteristics of chaotic dynamics found in active nematic suspensions.
• The self-organization into nematic domains and defect dynamics are key features of this system.
• Hydrodynamic theories of active nematics provide a valid framework for understanding HBEC collective behavior.