Cell Stiffness Governs Its Adhesion Dynamics on Substrate Under Shear Flow.

We develop an efficient numerical method to study adhesion dynamics of a single cell on a substrate under shear flow. This method is based on the coupling of Lattice Boltzmann fluid and coarse-grained cell models through immersed boundary method, and a probabilistic model is adopted to capture dynamics of ligand-receptor binding for adhesion. With such a model at hand, a phase diagram of the adhesion dynamics in terms of adhesion strength $\text{Ad}$ and stiffness of cell $\text{Ca}$ is established. Four types of motion, including free motion, stable rolling, stop-and-go, and firm adhesion, are found through our numerical simulations, depending on the adhesion strength $\text{Ad}$ and stiffness of cell $\text{Ca}$. In addition, demargination behavior of the cell occurs when reducing the adhesion strength $\text{Ad}$ in the regime of soft cells (high $\text{Ca}$). Such a demargination behavior is induced by the deformability of cell, resulting in a wall-induced lift force in the shear flow. Lastly, a scaling relation of a number of ligand-receptor bonds is obtained under the synergistic effect of $\text{Ad}$ and $\text{Ca}$. The present effort provides a robust and efficient way to understand the adhesion dynamics of cells on substrate in shear flow. The obtained results are useful in understanding the biological adhesion process and developing adhesion-based microfluidic technologies. [ABSTRACT FROM AUTHOR]