A novel in vitro flow system for changing flow direction on endothelial cells.

Atherosclerotic plaques localize to regions of flow disturbance, i.e. bifurcations, branch points and regions of high curvature. Shear stress in these regions can be multi-directional due to complex flow patterns such as time-varying vortices. However, commonly used in vitro flow models are incapable of changing flow orientation to any direction other than the reverse. We have developed a novel in vitro flow system to enable changes in flow direction to any angle. When cells were pre-aligned in laminar shear, and then rotated 90°, cells re-aligned over 24 h. Re-alignment involved actin remodeling by gradual rotation of actin stress fibers. This device will enable that analysis of how endothelial cells sense changes in flow direction as occur in vivo.