Effect of wall shear stress on macromolecule uptake into cultured endothelial cells

The purpose of this study is to reveal macromolecule uptake route (intercellular or intracellular) in the endothelial cell layer, and to examine the effect of wall shear stress on the uptake. After 48 hour exposure to shear stress, the endothelial cell layer on coverslips were incubated at 37°C for 60 minutes in PBS containing tetramethylrhodamine isothiocyanate conjugated albumin (TRITC-albumin). Thereafter, the uptake of albumin and the shape of endothelial cells were observed by a confocal laser scanning microscope (CLSM). Albumin is found in intracellular region, not in intercellular region. The albumin uptake depends on imposed shear stress. At 10 dyn/cm², the albumin uptake showed a 1.3 folds increase. The albumin uptake decreases with increasing shear stress, and minimum uptake is quarter of the control value at 60 dyn/cm². This shear dependence of uptake is an unique feature of the cell and may play a key role for the controlling mechanism of endothelial cells.