Changes to endothelial cell function induced by hydrogen peroxide : a model of cell senescence

Endothelial dysfunction is an early stage in atherosclerosis and is associated with oxidative stress, which occurs when reactive oxygen species are not fully compensated by cellular antioxidants. This study investigated the effects of hydrogen peroxide in a human endothelial cell model. EA.hy926 cells incubated for 1 hour at 37°C with increasing concentrations of hydrogen peroxide were investigated for DNA damage ('Comet' assay), changes in mitochondrial activity (MTT assay), apoptosis and necrosis (Annexin V assay), cell growth and senescence (changes in morphology, cell size, pH6 specific B-galactosidase (S-Gal) and telomere shortening). Changes in the expression of mRNA transcripts of thrombotic (tissue factor); fibrinolytic (tissue phasminogen activator and plasminogen activator inhibitor-1) and adhesion (ICAM-1) proteins were investigated using RT-PCR. Low (≤50muM) concentrations of hydrogen peroxide induced detectable, but reversible, DNA damage; which was accompanied only by a small decrease in mitochondrial activity. Intermediate levels of oxidative stress (