Viability assays for cells in vitro: the ethidium/calcein assay and the immunofluorescence combination assay

In neurotoxicology, studies have become more sophisticated and focus more on changes evident at the cellular and molecular level rather than on whole-animal morbidity. For this and other reasons, in vitro model systems are being incorporated into neurotoxicity screens and mechanistic studies. The use of in vitro systems allows for the isolation and culturing of cells specifically targeted by neurotoxicants and for the determination of cell viability following treatment with a neurotoxicant. A reliable in vitro cell viability assay is a critical component of any drug or neurotoxicant study (1).