Monitoring cell proliferation is essential for a variety of applications including optimizing cell culture conditions and determining activity rates of cytokines and growth factors. Cell proliferation measurement can also be useful in assessing cell-mediated cytotoxicity, the efficacy of therapeutic compounds in drug screening, and the cytostatic nature of anticancer compounds in toxicology testing.
Cell proliferation characteristics include cellular metabolic activity and cell membrane integrity. One method for measuring metabolic activity is to incubate the cells with a tetrazolium salt such as MTT, which is cleaved into a colored formazan product by metabolically active cells. Similarly, the green fluorescent dye Calcein AM can measure intracellular esterase activity in proliferating live cells, which is another indicator of cell viability.