Unidirectional pulsatile flow improves fibronectin and laminin reorganization and cell adherence of vascular endothelial cell

Cell adherence is a key factor in endothelialization of prosthetic vascular grafts and artificial valves. Flow conditions are proved to affect fibronectin (FN) and laminin (LN) organization of vascular endothelial cells (ECs), thereby changing ECs adherence. The blood flow in aortic is pulsatile, and the flow pulsatility is critical in ECs functions. However, effects of pulsatile flow on FN and LN organization and cell adherence of ECs are still unclear. In this study, rat aortic endothelial cells (RAECs) were exposed to steady laminar flow of 12 dyne/cm² and unidirectional sinusoidal flow with equivalent time-average shear stress of 12 dyne/cm² and a frequency of 1.25 Hz for 24hours, and then FN and LN reorganization and cell retention were investigated. Compared to steady laminar flow, FN fibrils under unidirectional pulsatile flow appeared to be thicker and formed a denser network. LN under unidirectional pulsatile flow formed in fibrillar pattern, no matter in the intercellular space or beneath the cells, and the LN fibrils tended to orient more regularly in the flow direction. After exposure to 40 dyne/cm² continuous laminar shear stress for 2h, 4h and 6h, the cell retention ratio under unidirectional pulsatile flow was much higher than steady laminar flow group. These results indicated that unidirectional pulsatile flow improves RAECs adherence by reorganization of FN and LN.