Traction and Stress Control Formation and Motion of +1/2 Topological Defects in Epithelial Cell Monolayers

Area of Science:

• Cell biology
• Biophysics
• Soft matter physics

Background:

• Topological defects in cell shape influence cell density, extrusion, and invasion.
• The formation mechanisms and effects of these defects on cell forces and motion remain unclear.

Purpose of the Study:

• Investigate the formation and dynamics of +1/2 topological defects in confluent cell monolayers.
• Quantify cell velocities, substrate tractions, and internal stresses near these defects.

Main Methods:

• Studied +1/2 topological defects in epithelial cell monolayers.
• Quantified cell velocities, cell-substrate tractions, and intra-layer stresses.
• Analyzed energy injection from stresses and tractions.

Main Results:

• Observed concurrent tail-to-head and head-to-tail motion of +1/2 defects.
• Identified both traction and stress as sources of activity and dissipation.
• Defect motion direction depends on energy injection from stresses versus tractions.
• Pre-defect formation patterns in motion, traction, and stress suggest defects arise from coordinated cell activity.

Conclusions:

• Coordinated patterns of cell forces and motion are crucial for topological defect formation and dynamics.
• +1/2 defect motion is driven by energy injection from stresses or tractions.
• Findings shift focus to the role of coordinated forces and motion in defect emergence.