Protective Effect of Zinc Chloride Against Cobalt Chloride-Induced Cytotoxicity on Vero Cells: Preliminary Results

The aim of this study was to investigate the possible time- and dose-dependent cytotoxic effects of cobalt chloride on Vero cells. The cultured cells were incubated with different concentrations of cobalt chloride ranging from 0.5 to 1,000 μM, and cytotoxicity was determined by 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) and resazurin assays. Possible protective effects of vitamin E, coenzyme Q10, and zinc chloride were also tested in this system. A gradual decrease in cell proliferation was observed at concentrations ~≥200 μM in incubation periods of 24, 48, 72, and 96 h with MTT assay. Exposure of cells to 500 and 1,000 μM cobalt chloride caused significant decrease in cell survival. A biphasic survival profile of cells was observed at 1–25 μM concentration range following 96 h of incubation. With resazurin assay, cytotoxicity profile of CoCl2 was found comparable to the results of MTT assay, particularly at high concentrations and long incubation periods. Dose-dependent cytotoxicity was noted following exposure of cells to ≥250 μM of CoCl2 for 24 h and ≥100 μM concentrations of CoCl2 for 48–96 h. Pretreatment of cells with ZnCl2 for 4 or 24 h provided significant protection against cobalt chloride-induced cytotoxicity when measured with MTT assay. However, vitamin E or coenzyme Q10 was not protective. CoCl2 had dose- and time-dependent cytotoxic effects in Vero cells. Preventive effect of ZnCl2 against CoCl2-induced cytotoxicity should be considered in detail to define exact mechanism of toxicity in Vero cells.