Effect of flow acceleration on deformation and adhesion dynamics of captured cells

Cell deformation and adhesion under shear flows play an important role in both cell migration in vivo and capture based microfluidic devices in vitro. Adhesion dynamics of captured cell (e.g., firm adhesion, cell rolling and cell detachment) under steady shear flows have been studied extensively. However, cell adhesion under accelerating flows is common both in vivo and in vitro, and dynamics of cell adhesion under accelerating flows remains unknown. As such, we used a mathematical model based on the front tracking method and investigated the effect of flow acceleration on deformation and adhesion dynamics of captured cells, including cell deformation index, cell shape evolution, the velocities of cell center, contact time and wall shear stress for cell rolling and detachment by using a series of parameter values for leukocyte. The results showed that the cell presented three dynamics states (i.e., firm adhesion, rolling and detachment) with increasing wall shear stress under uniform flows. Wall shear stresses were < 0.56 Pa and > 1.12 Pa for firm adhesion and detachment, respectively. The wall shear stresses were at the range 1.48-1.63 Pa (higher than 1.12 Pa) when cell left the bottom surface of the channel under flow accelerations (a = 0.975-1.625 m/s²). The minimum of deformation index under accelerating flow was smaller than that under uniform flow. In conclusion, the flow acceleration promotes the deformation and adhesion of captured cells. These findings could further the understanding of cell migration in vivo and promote the development of capture based microfluidic devices in vitro.