Cell Proliferation, Viability & Cytotoxicity
Cell proliferation rates or viability levels are good indicators of cell health. Proliferation or viability analysis is crucial for cell growth and differentiation studies, and are often coupled with metabolism analysis. Metabolic activity is commonly used as a viability indicator, but for some applications it can be important to assess viability independent of metabolic state and this is where the cell viability assays come in play. Proliferation is also a convenient measure of population dynamics in studies of cytokines or growth factors, or in bioprocess optimization work. On the other hand assessing compound cytotoxicity is also a critical step in pharmaceutical development. These assays in oncological settings are also used to evaluate both compound toxicity and inhibition of tumor cell growth during drug development. Cell viability in a particular experiment can depend on diverse criteria ranging from redox potential of the cell population, the ATP/ADP levels, the integrity of cell membranes, to the activity of cellular enzymes such as LDH and esterases. Therefore, biomarkers that can be quantified include ATP, NADH, Caspases, LDH, and live- and dead-cell proteases.
Cell viability/cytotoxicity assays can be classified into 4 types:
1) Functional assays, e.g., ATP levels.
2) Cytology / membrane leakage assays, e.g., LDH assays.
3) Mitochondrial assays, e.g., assays using Resazurin.
ATP is an excellent marker for cell viability because it is present in all metabolically active cells. ATP concentration declines rapidly when cells undergo necrosis or apoptosis. Therefore, monitoring ATP is a good indicator of cytocidal, cytostatic and proliferation effects. BioVision offers a diverse selection of assays measuring ATP and/or ADP levels. These assays can be used with different analysis platforms including colorimetry, fluorimetry and bioluminescence. With very flexible sizes, some of these assays can be used to detect as low as 10 fmol/assay (1 nM) of ATP.
Cytotoxicity assays are widely used by the pharmaceutical industry to screen for cytotoxicity in compound libraries. One of the most commonly used agents to measure cytotoxicity is LDH (lactate dehydrogenase). LDH is a soluble cytosolic enzyme that is released into the culture medium following loss of membrane integrity resulting from either apoptosis or necrosis. LDH activity, therefore, can be used as an indicator of cell membrane integrity and serves as a general means to assess cytotoxicity resulting from chemical compounds or environmental toxic factors. BioVision's multiple LDH cytotoxicity assays spanning both colorimetric and luminescent detections provide a fast and simple method for quantitating cytotoxicity based on the measurement of LDH activity in damaged cells.
Fluorescence-based assays can be used to examine cell viability or cytotoxicity of animal cells, bacteria, yeast and fungi using metabolic activity, membrane permeability or a combination of parameters. BioVision has an array of such cell viability measuring products. For e.g., BioVision's VisionBlue™ Quick Cell Viability Assay uses the redox dye Resazurin, which fluoresces brightly upon reduction by cells that are metabolically active. This dye is more sensitive than another popular dye, Alamar Blue, and needs only as few as 100 cells. And since the reagents are non-toxic, you can read plates at various times to follow cell proliferation dynamically. We also offer water-soluble tetrazolium salt - WST-8 based colorimetric cell proliferation kits, which are more sensitive than MTT/XTT/or MTS-based assays. Additionally, the entire assay can be performed directly in a 96-well plate, which provides information on whole cell populations rather than tracking the behavior of individual cells.
Thus, BioVision offers a diverse selection of assays and antibodies for the analysis of cell viability and vitality. In addition to the above mentioned products, we also offer live dead cell staining and senescence detection kits. All these products have been validated on multiple instrument platforms including microscopy, flow cytometry, microplate reader, and /or high content screening. These reliable, sensitive and easy-to-use kits can analyze cell growth regulation in response to growth factors, cytokines, mitogens, nutrients, chemicals, and many more conditions/reagents.