Cytotoxicity is the degree to which a substance can cause damage to a cell. A substance or process that causes cell damage or death is referred to as cytotoxic, "cyto" meaning cell and "toxic" meaning poison. Cells exposed to cytotoxic compounds may undergo necrosis (uncontrolled cell death), apoptosis (programmed cell death), autophagy, or stop actively growing and dividing to decrease cell proliferation.
Cytotoxicity assays measure the ability of cytotoxic compounds to cause cell damage or cell death. Cytotoxicity assays are widely used in fundamental research and drug discovery to screen libraries for toxic compounds. In drug discovery, cytotoxicity is a critical endpoint when evaluating the fate and effects of a compound. A compound generating a cytotoxic response may be eliminated from subsequent screening rounds when evaluating potential pharmaceutical treatments, or a compound targeting rapidly dividing cells may constitute a “hit” in a drug screen aimed at identifying cancer therapeutics.
Cell viability can be detected through various mechanisms, such as membrane integrity, enzyme activity, or metabolic activity. Each viability reagent forms the basis of an assay to evaluate cell heath through a single-parameter readout or using multiple measures of detection—viability kits. Additionally, ready-to-use options are available for your everyday experimental needs. Viability assays are used to evaluate the response to internal or external stimuli, such as the cytotoxic effects from drug screenings.
Autophagy, meaning “self-eating”, is a lysosome-dependent process that systematically degrades and recycles cellular components. A variety of assays are available to identify the induction of autophagy, clearance of protein aggregates, or inhibition of autophagy. Lysosomal markers are also available for tracking fusion with autophagosomes prior to degradation or tracking lysosomal behavior.
