How does MTT assay determine cell viability?

MTT assays determine cell viability through a specific process. Firstly, it is important to note that the monocyte cell viabilities are frequently tested, as well as BMVEC’s and NHAs. To calculate viabilities, the MTT assay measures the growth rate of cells based on the relationship between their cell activity and absorbance. So, if you are running a typical experiment you would incubate 10,000 cells suspended in 100 microliters of media with 10 microliters of MTT reagent for 3 hours. You then add a detergent solution for lysing the cells for the solubilization of formazan crystals. Then the color produced at the coulometric detection(at 570nm)  is proportional to the number of viable cells. The darker the color is, the more viable cells there are.