Surface deformation and shear flow in ligand mediated cell adhesion

The behavior of cell adhesion under fluid forces is not fully understood. Prior research has shown that cells coated with ligands can experience both attractive and repulsive forces in ionic solutions. However, the exact mechanism of how these forces influence adhesion and detachment remains unclear. It was already known that ligand binding involves both rotational resistance and electrostatic effects. But the role of shear flow in modulating these interactions had not been fully resolved. This gap motivated the development of a model that integrates fluid mechanics with cell deformation. The study addresses a need to quantify adhesion transitions in dynamic fluid environments. No prior work had resolved the bistable behavior of adhesion and fragmentation under shear. This paper introduces a novel approach to model these complex interactions.

The aim of this study was to develop a unified model for cell adhesion dynamics under shear flow. The specific problem addressed is how ligand-mediated adhesion behaves in an ionic fluid with shear forces. The motivation stems from the need to understand adhesion transitions in biological systems. The model considers both cell deformation and ligand interactions in a fluid medium. The researchers propose to use lubrication theory and numerical methods to calculate drag forces. The study focuses on how fluid parameters influence adhesion and fragmentation. The goal is to identify the conditions under which bistability occurs. This work provides a framework to predict adhesion behavior in controlled fluid environments.

The researchers developed a multiscale model to simulate cell adhesion dynamics. They combined lubrication theory with numerical results to calculate drag forces. The model accounts for the deformation of near-spherical cells under shear flow. The cells are coated with ligands that resist rotation and experience electrostatic forces. The study uses a viscous, ionic fluid as the medium for cell interactions. The model incorporates both attractive and repulsive ligand forces. The sticking probability curves are analyzed to identify phase transitions. The researchers use material and fluid parameters to test adhesion and fragmentation regimes.

The study found that adhesion is favored in highly ionic fluids and with increased cell deformability. The researchers observed a hysteretic transition between adhesion and fragmentation phases. The sticking probability curves showed a nonlinear relation to the separation gap. Elastic binders and higher fluid shear rates also promoted adhesion. The model predicted a bistable region within a range of critical shear rates. The limit points of the sticking probability curves indicated abrupt transitions. The study confirmed that bistability occurs in adhesion-fragmentation phase diagrams. These findings suggest that adhesion dynamics are highly sensitive to fluid and material parameters.

The authors propose that adhesion dynamics are influenced by fluid ionic strength and cell deformability. They suggest that elastic binders and shear rate play a role in adhesion transitions. The study indicates that bistability can occur within a specific shear rate range. The researchers propose that the sticking probability curves reflect nonlinear ligand interactions. They suggest that the model captures the complex interplay between fluid forces and cell deformation. The findings imply that adhesion is sensitive to fluid parameters and ligand properties. The authors propose that this model can predict adhesion behavior in controlled environments. These results align with prior in vitro observations of bistable adhesion transitions.