MTT-A Cell Proliferation Assay is based on the transformation and colorimetric quantification of MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. The respiratory chain and other electron transport systems reduce MTT and other tetrazolium salts. As a result, non-water-soluble violet formazan crystals accumulate within the cell. The amount of these crystals can be determined using a spectrophotometer, serving as an estimate of the number of mitochondria and, hence, the number of living cells in the sample. These features allow performing cytotoxicity or cell proliferation assays, which are widely used in immunology, toxicology, and cellular biology.
In the MTT-A cell proliferation assay is necessary to remove the cell medium before resuspending MTT crystals formed.