Does grape seed extract potentiate the inhibition of platelet reactivity in the presence of endothelial cells?

PurposeNumerous studies have suggested that grape seed extract (GSE) confers vascular protection due to the direct effect of its polyphenol content on endothelial cells. The aim of the study was to determine whether GSE confers vascular protection through the direct effect of its polyphenol content on endothelial cells.Material/methodsAfter incubation with GSE-treated human umbilical vein endothelial cells (HUVECs), blood platelet reactivity was evaluated with regard to the expression of CD62P and the activated form of GPIIbIIIa in ADP-stimulated platelets.ResultsLower concentrations of GSE were found to enhance the antiplatelet action of HUVECs: 1 μg/ml GSE reduced platelet reactivity by about 10%. While platelet reactivity was not altered by HUVECs incubated with higher concentrations of GSE, HUVEC proliferation was significantly reduced by GSE of up to 10 μg gallic acid equivalent/ml.ConclusionsThe results of the study show that low doses of GSE potentiate the inhibitory action of HUVECs on platelet reactivity, which may account, at least partially, for the protective effects of grape products against cardiovascular diseases. In contrast, high concentrations of GSE significantly impair endothelial cell proliferation in vitro.