Cell culture cytotoxicity testing is used as a predictor for animal toxicity. High-throughput cytotoxicity screening using ATP levels as an indicator of cell viability is the current gold standard for such predictive cytotoxicity testing. Multiplexing assay chemistries allows researchers to measure multiple parameters on a single sample in order to get a more complete picture of what is happening when cells are exposed to a treatment compound. For example multiplex assays using three protease activities as markers of viable, necrotic and apoptotic cells give researchers a tool for uncovering the mechanism of cell death when toxicity is observed and control for assay artifacts. In their book chapter, “Cytotoxicity Testing: Measuring Viable Cells, Dead Cells and Detecting Mechanism of Cell Death”, Riss, Moravec and Niles, describe protocols for in vitro toxicity testing using ATP-based assays and multiplex assays. The chapter provides protocols, an extensive materials required list, example data, and a thorough notes section describing appropriate controls, issues of assay timing, and other considerations that affect assay success. You can find it in Methods in Molecular Biology Vol. 740, Mammalian Cell Viability Methods and Protocols (Humana Press).
Life is complicated. So is death. And when the cells in your multiwell plate die after compound treatment, it’s not enough to know that they died. You need to know how they died: apoptosis or necrosis? Or, have you really just reduced viability, rather than induced death? Is the cytotoxicity you see dose-dependent? If you look earlier during drug treatment of your cells, do you see markers of apoptosis? If you wait longer, do you observe necrosis? If you reduce the dosage of your test compound, is it still cytotoxic? Continue reading “Describing Life and Death in the Cell”