Reliable, hands-free, and high-throughput cell viability assays on the MACSQuant® Flow Cytometer.
The determination of cell viability in any cell culture is a crucial analytical measurement for any study. This includes high-throughput cytotoxicity screens of large libraries of compounds and drug discovery research, and studies in all laboratories interested in validating their cell cultures upstream or downstream of any given application.
One of the most common ways to measure cell viability, due to the simplicity of the application, is via the determination of the cell membrane’s integrity. This is done by using fluorescent dyes which are capable of penetrating the membranes of damaged/dying cells and binding to nucleic acids inside the cell nucleus. It is thought that only non-viable cells allow these dyes to enter and therefore only these cells will give a positive readout. One of the most commonly used probes for this kind of viability tests is propidium iodide (PI), which intercalates into double-stranded nucleic acids and owes its success to its low cost, rapid cell penetration kinetics, and convenient excitation and emission spectra.
To date, the majority of high-throughput cell viability assays have been performed using plate readers, due to their ease of use and the option to process entire plates very quickly. However, plate readers, while capable of providing high throughput, can only give an average of the fluorescence
(and thus cell viability) of an entire well, but not at the single cell level. In contrast, flow cytometers can analyze thousands of events per well, and thus provide detailed high-content information on the viability and phenotype of single cells as well as the cell count of the entire well at the same time.