Oleacein protects endothelial progenitor cells against angiotensin II – induced oxidative stress

Oleacein is a secoiridoid from Olea europaea L. (Oleaceae) occurring mainly in olive oil. The latest in vitro studies show that oleacein is a potent antioxidant, and thus may prevent oxidative stress, LDL oxidation and oxidative DNA damages. Endothelial progenitor cells (EPC) constitute a basic repair mechanism of damaged blood vessels, but these cells are especially sensitive to oxidative stress. The aim of the study was to examine whether oleacein may protect EPCs against impair of function due to oxidative stress induced by angiotensin II. EPCs were isolated from peripheral blood of young healthy volunteers and cultivated on fibronectin-coated plates in EGM-2 medium in the presence or absence of angiotensin II (1µM) and oleacein (2–50µM). Cell senescence was measured using a β-galactosidase staining kit; ROS generation was measured using a ROS/Superoxide detection kit; expression of heme oxygenase-1, nitrotyrosine formation and oxidative DNA damages were measured using ELISA kits. Angiogenic potential was measured by tube formation in Matrigel™. Oleacein reduced cell senescence increased by angiotensin II and inhibited ROS formation. These effects resulted in reduction of nitrotyrosine and oxidative DNA damages formation. Moreover, oleacein increased the angiogenic potential of EPC in vitro. This activity of oleacein was correlated with the increase of heme oxygenase-1 expression. Our results suggested that oleacein may protect EPC against angiotensin II-induced oxidative stress.