Cytotoxicity cells

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.

Enzymatic cytotoxicity assays

increasing cytotoxicity and decreasing viability

Lactate dehydrogenase (LDH) and glucose 6-phosphate dehydrogenase (G6PD) are enzymes present in many different cell types. When the cellular plasma membrane is damaged, LDH and G6PD will be released in the cell culture medium. CyQUANT Cytotoxicity Assay Kits are colorimetric- or fluorescence-based detection methods to quantitively measure cytotoxicity through the release of LDH or G6PD, which act as biomarkers for cellular cytotoxicity.

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Viability assays

Cells with red-orange cytoplasm, green mitochondria, and blue nucleiCell 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.

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Apoptosis assays

Cell undergoing apoptosis

Apoptosis, or programmed cell death, allows for proper growth and development of an organism by eliminating excess cells and tissue waste from damaged or infected cells. Biochemically, apoptosis results in morphological changes, such as genome fragmentation and cleavage or degradation of cellular proteins.

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Autophagy assays

Cells with red autophagy sensor, green tubulin, and blue nuclear dyeAutophagy, 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.

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Cell proliferation assays

Schematic of proliferating cells

The analysis of cell proliferation is crucial for cell growth and differentiation studies, as well as cancer research, and is often used to evaluate both compound toxicity and inhibition of tumor cell growth during drug development. Markers for measuring cell proliferation include average DNA content and cellular metabolism in a population. Cell proliferation assays are available that report total cell number, total number of live cells, or provide single-cell indication of DNA synthesis.

Lipotoxicity assays

Lipid accumulation with cell lysosome membranes

Phospholipidosis and steatosis are toxic side effects of lipid metabolism that can be triggered by drugs or other compounds. Phospholipidosis is characterized by the accumulation of excess phospholipid complexes within the internal lysosomal membranes. Steatosis is the retention of lipids due to abnormal synthesis and elimination of triglyceride fats.

Mitotoxicity assays


Mitochondrial function is an important parameter in cytotoxicity and can be monitored by measuring mitochondrial membrane potential, calcium flux, or reactive oxygen species. Probes for mitochondrial structure and function are often multiplexed to explore other cell health parameters and answer complex biological questions on cytotoxicity or drug efficacy using imaging, microplate, or flow cytometry platforms.

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Cell Analysis Learning Center—Find educational resources such as application notes, webinars, videos, articles, and more that cover the use of many of our reagents and kits for cell analysis.

Flow Cytometry Panel Builder—Design your flow cytometry panel with this online tool for a simplified, customizable experience to fit your needs.

Fluorescence SpectraViewer—Online tool for visualization of the excitation and emission of fluorescent reagents; allows for checking spectral compatibility for multiple fluorophores.

For Research Use Only. Not for use in diagnostic procedures.