The effect of fluid shear stress in hydrogen sulphide production and cystathionine γ-lyase expression in human early endothelial progenitor cells

BACKGROUND: Physiological fluid shear stress has been shown to have a beneficial impact on vascular homeostasis. Endothelial progenitor cells (EPCs) make a significant contribution to maintaining endothelial integrity. Therefore, we hypothesised that shear stress-induced endothelium protection plays a role in hydrogen sulphide (H(2)S) production and up-regulation of cystathionine γ-lyase (CSE) expression in EPCs. METHODS: Human EPC-derived CSE activity was detected by colorimetric assay, and H(2)S production was evaluated by membrane adsorption method. Cell proliferation, migration, and adhesion were assessed by MTT, Transwell, and endothelial cell-mediated adhesion assays, respectively. Real-time polymerase chain reaction (RT-PCR) was carried out to analyse gene expression. Protein expression was analysed by western blot. RESULTS: Human EPCs were treated with shear stress levels of 5–25 dyn/cm(2) for up to 3 h, and 25 dyn/cm(2) for up to 24 h. H(2)S production and CSE mRNA expression in the EPCs were increased by shear stress in a dose-dependent manner in vitro. Likewise, time-dependent shear stress also significantly enhanced CSE protein expression. Compared to static condition, shear stress improved EPCs proliferation, migration and adhesion capacity. Knockdown of CSE expression by small interfering RNA substantially eliminated the shear stress-induced above functions of human EPCs in vitro. CONCLUSIONS: This study gives new insight into the regulatory effect of physiological shear stress on the CSE/H(2)S system in human EPCs. Our findings may contribute to the development of vascular protective research, although the relevant evidence is admittedly indirect.