Mechanical Model for Catch-Bond-Mediated Cell Adhesion in Shear Flow

Area of Science:

• Biophysics
• Cellular Mechanics
• Adhesion Dynamics

Background:

• Catch bonds, which strengthen under tension, mediate cell rolling adhesion in fluid environments.
• The precise mechanical mechanisms of catch bond-mediated cell rolling under shear flow remain unclear.

Purpose of the Study:

• To develop a mechanical model for catch bond-mediated cell adhesion in shear flow.
• To elucidate the kinetic and dynamic factors governing cell rolling under hydrodynamic forces.

Main Methods:

• A Markovian process model for bond dynamics (formation/dissociation).
• Classical analytical mechanics for cell motion.
• Monte Carlo simulations for theoretical prediction verification.

Main Results:

• Cellular steady state is highly dependent on shear flow rate.
• Identified critical shear rates for cell attachment and detachment.
• Observed flow-enhanced adhesion where slower, regular cell rolling occurs with increased shear rates.
• Demonstrated flow-enhanced stability results from a balance between bond stochasticity and cell dynamics.

Conclusions:

• The study challenges the traditional view that force-induced lifetime extension is the sole driver of flow-enhanced adhesion.
• Highlights the interplay between stochastic bond reactions and cell rolling dynamics.
• Predicts flow loading history influences adhesion bistability, aligning with experimental findings.