Toxicity of dimethyl sulfoxide as a solvent in bioassay system with HeLa cells evaluated colorimetrically with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide.

The toxicity of dimethyl sulfoxide (Me2SO) was examined in HeLa cells cultured at 37 degrees C for up to 72 hr. The growth of the cells was measured by a colorimetric method with the use of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), which gave good correlation between the cell number and the color development from the reduction of MTT under suitable conditions. When the initial number of cells was 3 x 10(4)/ml, Me2SO at 1% or less had no apparent effect on proliferation for up to 48 hr of incubation, but in longer incubations, cell growth was repressed. When the initial number of cells was 3 x 10(5)/ml, the effect of Me2SO was similar.