A cell viability assay measures the number (relative or absolute) of living cells in a sample. Viability is a function of cellular proliferation and death. Cytotoxicity assays measure the number (relative or absolute) of dead cells. Viability and cytotoxicity assays provide complimentary information about cell health effects of compounds. A variety of cell viability and cytotoxicity assays are available. We routinely multiplex the CellTox Green assay for cytotoxicity with the CellTiter-Glo assay for viability. These two assays are affordable and can be scaled to test many compounds across high-resolution dose-ranges in a single experiment.
CellTox Green is a nucleic acid dye that is excluded from living cells, but which can enter dead cells where it stains the nuclei. By high-content imaging, the number of dead cells per sample can be counted. Dye may be added at the time of treatment and images acquired for several days thereafter, providing a timecourse of cytotoxicity. This can be useful, because the presence of intact dead cells in a culture may be transient. CellTiter-Glo is a luminescent assay for ATP. Live cells contain ATP, and so ATP levels are assumed proportional to the number of live cells. Viability is measured at the end of the treatment period. An example of the use of the CellTiter-Glo assay is provided below.
CellTiter-Glo Viability Assay example. A549 cells were exposed to a dose-range of paraquat for the indicated durations and then assayed for viability with the CellTiter-Glo Viability Assay. The response is displayed in terms of sample ATP content as a percent of the vehicle-treated samples. Points and error bars are means and standard deviations of triplicate samples.
