Cell proliferation has multiple functions in development and pattern formation. That includes roles in growth, morphogenesis and gene expression. Methods commonly used for this purpose are hemocytometer counting, determination of protein content, wet or dry weight measurement, and determination of the optical density (OD). However, hemocytometer counting and protein determination are time-consuming and tedious. In addition, measurement of wet or dry weight is not practical for very small culture volumes.
This method bases 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 user can determine the amount of these crystals using an 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.
MTT Cell Proliferation Assay Kit A
The principle of Bioquochem’s MTT Cell Proliferation Assay Kit A is the quantification of mitochondrial activity. For viable cells, mitochondrial activity is constant. Therefore, an increase or decrease in the number of viable cells linearly relates to mitochondrial activity. The mitochondrial activity of cells is equivalent to the conversion of the tetrazolium salt MTT into formazan crystals, which can be solubilized for homogenous measurement. Thus any increase or decrease in viable cell number can be detected by measuring formazan concentration spectrophotometrically using a plate reader at 570 nm vs 690 nm.
Figure 1. Reduction of MTT to formazan