Green tea extract protects endothelial progenitor cells from oxidative insult through reduction of intracellular reactive oxygen species activity

Objective(s):Many studies have reported that tea consumption decreases cardiovascular risk, but the mechanisms remain unclear. Green tea is known to have potent antioxidant and free radical scavengingactivities. This study aimed to investigate whether green tea extract (GTE) can protect endothelial progenitors cells (EPCs) against oxidative stress through antioxidant mechanisms. Materials and Methods: Mononuclear cells (MNCs) were isolated from peripheral blood by density gradient centrifugation with Ficoll. The cells were then plated on fibronectin-coated culture dishes. After ۷ days of culture, EPCs were characterized as adherent cells double positive for DiI-ac-LDL uptake and lectin binding. EPCs were further identified by assessing the expression of CD۳۴/۴۵, CD۱۳۳, and KDR. EPCs were then treated with hydrogen peroxide (H۲O۲) at doses of ۵۰, ۱۰۰, ۲۰۰ µM and incubated with or without GTE (۲۵ µg/ml). The intracellular reactive oxygen species (ROS) levels were detected by flow cytometry using a ۲’,۷’-dichlorofluorescein diacetate (DCF-DA) fluorescentprobe. Results: GTE ameliorated the cell viability of EPCs induced by H۲O۲ at doses of ۵۰, ۱۰۰, ۲۰۰ µM for about ۲۵.۴۷, ۲۲.۵۲, and ۱۱.۹۶% higher than controls, respectively. GTE also decreased the intracellular ROS levels of EPCs induced by H۲O۲ at doses of ۵۰, ۱۰۰, ۲۰۰ µM for about ۸۴.۲۴, ۹۲.۲۷, and ۹۳.۷۲% compared to controls, respectively. Conclusion: GTE improves cell viability by reducing the intracellular ROS accumulation in H۲O۲-induced EPCs.

Keywords:

Antioxidant , Endothelial progenitor cells , green tea , Oxidative stress , Reactive Oxygen Species