Gene silencing of E-selectin block recruitment of endothelial progenitor cell to vascular endothelium under flow

Short interfering RNA (siRNA) is a powerful technique that can suppress gene expression in a variety of cells including mammalian cells. Endothelial progenitor cells (EPCs) are bone marrow—derived haematopoietic progenitor cells that have been implicated in vasculogenesis. We demonstrated for the first time that gene silencing of endothelial E-selectin using siRNA transfection in human umbilical vein endothelial cells (HUVECs) causes inhibition of EPC adhesion under flow conditions. Fluorescence immunobinding assay analysis showed that significant reduction of E-selectin surface expression in HUVECs (activated with IL-1β (10 U/mL) for 4 h) transfected with siRNA against E-selectin, but not in HUVECs transfected with LacZ siRNA (control). An EPC adhesion assay under flow conditions (shear stress = 1.0 dyne/cm) then demonstrated that HUVECs transfected with E-selectin siRNA supported significantly less adhesion of EPCs than those HUVECs treated with control siRNA and no siRNA after activation by IL-1β (p < 0.05). Our experiments have shown the importance of E-selectin in EPC adhesion to HUVECs and the potential utility of gene silencing of E-selectin in EPC recruitment.