[DUAL PROAPOPTOTIC AND PRONECROTIC EFFECT OF HYDROGEN PEROXIDE ON HUMAN UMBILICAL VEIN ENDOTHELIAL CELLS].

The ratio of early apoptosis and late apoptosis (necrosis) in the cultured human umbilical vein endothelial cells was estimated after exposure to hydrogen peroxide (H2O2) in vitro trying to keep them close to the physiological conditions (high cell density, high serum content, H2O2 concentration not over 500 μM). Cell viability was assessed using flow cytometry and simultaneous staining with fluorescent dyes PO-PRO-1 to detect early apoptotic cells, and DRAQ7 to detect late apoptotic and necrotic cells. The data obtained suggest that the primary mechanism of cytotoxic response is apoptosis. The critical concentration of H2O2 causing the death of the cell population in a dense monolayer is 250 μM. Lower concentrations of H2O2 (up to 200 μM) cause death of individual cells; however, viability of endothelial cell population is retained, and response to calcium activating agonists does not change compared with control cells.