Vascular endothelial cells (ECs) play significant roles in regulating circulatory functions.Mechanical stimuli, including the stretch and shear stress resulting from circulatory pressure and flow, modulate EC functions by activating mechano-sensors, signaling pathways, and gene and protein expressions.Mechanical forces with a clear direction (e.g., the pulsatile shear stress and the uniaxial circumferential stretch existing in the straight part of the arterial tree) cause only transient molecular signaling of pro-inflammatory and proliferative pathways,which become down-regulated when such directed mechanical forces are sustained.