Abstract
Endothelial cell injury is an essential component of atherosclerosis and hypertension. Atherosclerosis and other macrovascular diseases are the most common complications of diabetes. Vaccarin is a major flavonoid glycoside in Vaccariae semen, and is expected to be useful in the treatment of vascular diseases. The aim of the present study was to evaluate the possible effects of vaccarin in human umbilical vein endothelial cells (EA.hy926) induced by hydrogen peroxide (H2O2) and its underlying mechanism in the prevention and treatment of H2O2 injury. In this study, the EA.hy926 cells were exposed to 250, 500 and 1000 µM H2O2 for 2 and 4 h in the absence or presence of vaccarin, and the cell injury induced by H2O2 was examined via SRB. Cell migratory ability, lactate dehydrogenase (LDH) leakage, malondialdehyde (MDA) levels and decreasing superoxide dismutase (SOD) activity were evaluated by the wound healing assay and corresponding assay kits. Cell apoptosis was detected by flow cytometry with Annexin V-fluorescein isothiocyanate/propidium iodide Apoptosis Detection kit and Hoechst staining. Furthermore, western blot detected the protein expressions of Notch1, Hes1 and caspase-3. Following treatment with H2O2, it was found that H2O2 stimulated cell injury in a dose-dependent manner, including reducing cell viability and cell migratory ability, increasing LDH leakage and MDA levels, and decreasing SOD activity. H2O2 further accelerated cell apoptosis via activation of Notch1 and the downstream molecule Hes1. Preincubation with vaccarin was found to protect EA.hy926 cells from H2O2-induced cell oxidative stress injury, which promoted cell viability and cell migratory ability, inhibited the level of LDH and MDA, but enhanced the activity of SOD. In particular, in addition to downregulation Notch signaling, vaccarin treatments also downregulated caspase-3, a cell apoptotic pathway-related protein. These findings indicated that vaccarin may be able to selectively protect vascular endothelium from dysfunction induced by H2O2.