Rapid fluorometric assay for cell viability and cell growth using nucleic acid staining and cell lysis agents

The purpose of this study was to establish a new method for rapidly and simply assessing cell viability and growth with objective validation if the assay system proceeded under suitable conditions of cell culture. In this method, a cell lysis agent was combined with a fluorescent probe for nucleic acid which exclusively passes through the disrupted membranes of dead cells but not intact membranes of viable cells. The distinctive feature of this probe is to possess a large fluorescence enhancement (460-fold) on binding to nucleic acid despite very low intrinsic fluorescence. In this fluorometric assay based on cell lysis and staining (FACLS), the fluorescence intensity was linearly related to total tumour cell number. This FACLS was also used to evaluate the chemosensitivity of MOLT-4 human leukaemia cells and to measure cell viability. The results were similar to those obtained by MTT colorimetric and trypan blue exclusion assays. The main advantage of this assay is its ability to measure simultaneously both cell viability and cell growth rapidly (within about 5 min) and simply (two steps) with validation of cell culture conditions in each microplate. This method could be widely applicable to cytotoxic evaluation of anticancer drugs and other chemicals.