ABSTRACT
This chapter provides an overview of the frequently used cytotoxicity assay techniques to estimate cell viability. Cell viability denotes the number of healthy cells in culture, but cannot distinguish between the cells that are actively dividing and those in the quiescent phase. Cytotoxicity of any sample is the quality of being toxic to cells and is expressed in terms of half-maximal inhibitory concentration values. Trypan blue (TB) exclusion assay is one of the most frequently employed procedures for evaluating cell viability. Calcein Acetoxymethyl (Calcein-AM) is a nonfluorescent hydrophobic dye that can be used to assess cell viability. Propidium Iodide (PI) and 7-Aminoactinomycin D (7-AAD) are membrane impermeable fluorescent dyes, generally excluded from viable cells. Lactate dehydrogenase (LDH) catalyzes the transformation of pyruvate to lactate and back, during the conversion of NADH to NAD+ and back. Metabolic activity is as an indication of cell viability and the metabolic assays measure the vital functions characteristic of viable cells.
