Shear stress increases Cu/Zn SOD activity and mRNA expression in human endothelial progenitor cells

Endothelial progenitor cells (EPCs) are involved in endothelial repair. However, the function of EPCs is impaired in the presence of cardiovascular risk factors. Therefore, upregulation of functional gene expression and bioactive substance production such as superoxide dismutase ( SOD) activity and mRNA expression in EPCs may contribute to the maintenance of EPC-related endothelial repair. EPCs from human peripheral blood mononuclear cells were exposed to in vitro 5, 15 and 25 dyn/cm(2) shear stress for 5, 15 and 25 h, respectively. Shear stress in a dose- and time-dependent fashion increased Cu/Zn SOD activity of human EPCs. Shear stress also upregulated the Cu/Zn SOD mRNA expression of human EPCs, indicating that an increase in Cu/Zn SOD activity induced by shear stress was mediated by enhanced transcription. Our data are the first time to show that in vitro shear tress enhances mRNA expression and activity of Cu/Zn SOD in human EPCs, suggesting that shear stress can be used as a novel means of manipulation to improve functional potential of EPCs. The augmentation in copper/ zinc-containing enzyme (Cu/Zn SOD), with subsequent accelerated superoxide anion (O-2(-)) inactivation, might increase locally nitric oxide ( NO) biological availability, which contributes to EPC-related vascular protection.