Endothelial cells in a microfluidic channel. (a) Human umbilical vein endothelial cells were cultured in a microfluidic channel. When reaching confluence, the cells were fixated with paraformaldehyde and stained for actin filaments (green) and nuclei (blue). Scale bar is 50 . (b) Endothelial cells that are subjected to physiological levels of shear stress inside microfluidic channels reorient their actin cytoskeleton to align with the direction of fluid flow (right). Scale bars are 50 .
