Reactive oxygen species contribute to simulated ischemia/reperfusion-induced autophagic cell death in human umbilical vein endothelial cells

BACKGROUND: Autophagy is important for cells to degrade protein aggregates and organelles. Our preliminary study suggests that ischemia/reperfusion in rabbit hearts promoted autophagic myocardial injury, resulting in no-reflow phenomenon. In this study, we sought to further understand the mechanism and outcome of the upregulation of autophagy in ischemia/reperfusion. MATERIAL/METHODS: We employed a simulated ischemia/reperfusion (sI/R) model in human umbilical vein endothelial cells (HUVECs) in vitro, in the presence or absence of antioxidants. RESULTS: Our study confirms that sI/R induces autophagy in HUVECs as measured by increased expression of Beclin 1 and microtubule-associated protein 1 light chain 3 (LC3), electron microscopic analysis, and special biofluorescent staining with monodansylcadaverine. This sI/R-induced autophagy was also accompanied by increased levels of p65 protein expression and cell death. In addition, we detected the accumulation of reactive oxygen species (ROS) after sI/R. Moreover, with the application of ROS scavengers that block the release of ROS, we were able to demonstrate that inhibition of autophagy increases cell survival. CONCLUSIONS: The study suggests that ROS accumulation is involved in the sI/R-induced autophagic cell death in HUVECs.