Endothelial-derived nitric oxide impacts vascular smooth muscle cell phenotypes under high wall shear stress condition

The Phenotypic states of vascular smooth muscle cells (SMCs) are essential to understanding vascular pathophysiology. SMCs in vessels generally express a specific set of contractile proteins, but decreased contractile protein expression, indicating a phenotypic shift, is a hallmark of vascular diseases. Recent studies have suggested the relation of abnormally high wall shear stress (WSS) of approximately 20 Pa with the aortic disease pathogenesis. However, due to the lack of appropriate experimental models to assess SMC phenotypic states, the details of the phenotypic shift under high WSS conditions remain unclear. In this study, we developed a coculture model where vascular endothelial cells (ECs) were cocultured with SMCs expressing calponin 1, a contractile protein involved in the phenotypic shift of SMCs. We investigated the effects of a pathologically high WSS condition on the phenotypic states of SMCs. Increased calponin 1 expression was found upon exposure to 20 Pa WSS compared with a physiological 2 Pa condition, whereas the expression of another contractile protein, α-smooth muscle actin (αSMA) remained unchanged. Furthermore, the inhibition of EC-derived nitric oxide (NO), which is associated with endothelial dysfunction in vascular diseases, resulted in a trend of decreasing αSMA and Calponin 1 expression under 20 Pa WSS conditions compared with 2 Pa. Our findings suggest that EC-derived NO under pathologically high WSS conditions may impact the expression of contractile proteins implicated in aortic pathophysiology.