Standardization of the 3-(4,5-Dimethylthiazol-2-yl)-5-(3-Carboxymethoxyphenyl)-2-(4-Sulfophenyl)-2H-Tetrazolium, Inner Salt (MTS) Assay for the SK-N-SH, KYSE-30, MCF-7, and HeLa Cell Lines

One common way to examine toxicity in vitro is to measure the effect on cell viability. In one such assay, the 3-(4,5- dimethylthiazol-2-yl)-5-(3 -carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt MTS reagent is bioreduced to a formazan product in living cells. Various cell lines may have differing abilities to reduce MTS; therefore, standardization should be carried out for each one. To optimize the assay, the toxicity of MTS, the linear range for signal versus cell number, and a method of background noise reduction were determined. The MTS reagent decreased cell number after 25 hr. The linear range for the neuronal SK-N-Sll, esophageal KYSE-30, breast MCF-7, and cervical HeLa cell lines were established. Finally, media containing no phenol red significantly reduced background noise compared to media with phenol red.