Effects of homocysteine on the expression of thrombomodulin in human endothelial ECV 304 cells

Objective:To evaluate the effects of homocysteine on the expression of thrombomodulin in cultured endothelial cells. Methods:Human umbilical veins endothelial cells (ECV-304 strain) were exposed to different levels of Hcy(0?25?50?100 μmol/L?1?5?10 mmol/L)for 24 hours. And then cell viability was determined by MTT assay, and lactate dehydrogenase (LDH) released into the culture medium was measured to assess cell damage. The antigen levels of the soluble thrombomodulin shedded from cell surface molecules were measured in the culture supernatants by using ELISA (Diagnostica Stago, France). Furthermore, the total TM was measured by using cellular ELISA. Results:There were no signs of cell toxicity induced by Hcy (0-1mM) in terms of cell viability, LDH leakage and the shedding of sTM in culture media during 24 hours of incubation. The endothelial cells exposed to concentrations up to 5mM exhibited a decreased cell viability and higher level of Hcy (10mM) induced a significant cytotoxic effects: decreased cell viability, significant LDH leakage and increased sTM in culture media, compared with the control cells. The protein of TM was positive in all groups. Hcy promoted the production of TM in endothelial cells and the effect was significant when Hcy concentration was greater than 1mM. Conclusion:The low physical concentration of Hcy has no signs of cell toxicity but nonphysiological high homocysteine levels can result in a variety of cellular effects, which include the influence on the expression of TM.