For obvious reasons, cell viability is an important part of any cell-based assay. That’s why researchers worldwide often try to include some measurement of cell viability in their assay design schema. Like everything in biotechnology, there are many ways to measure cell viability, some of which were presented at the recent annual conferences of the Society for Biomolecular Sciences (SBS) and the American Association of Immunologists (AAI).
For example, Sarah Roberts-Thomson, Ph.D., assistant professor at The University of Queensland, uses MTS cell viability assays to assess the functional consequences of inhibition and overexpression of specific calcium transporters in cancer cell lines.
“Our work is all about identifying and characterizing novel therapeutic targets for cancer, specifically breast and colon cancer,” she said. Her group presented data at the SBS meeting showing the use of these assays to assess the consequences of overexpression of a calcium-permeable ion channel on the viability of a breast cancer cell line.
“Cell viability measurement is a common application of flow cytometry,” said Maria Dinkelmann, Ph.D., lab manager at Accuri Cytometers. “Rather than using more traditional methods, which can be more laborious and less precise, individual researchers that have access to flow cytometry can better measure cell viability either on its own or in conjunction with another biomarker.”
One of the most common traditional techniques used to determine cell viability is the hemocytometer, which is basically a grid that is etched into a metal microscope slide. The typical method calls for the use of Trypan Blue, which is taken up by dead cells but not by viable cells. After mixing their sample with the dye and then applying this mixture to the hemocytometer slide, a researcher will literally count the cells by eye using a light microscope and compare the number of cells that have taken up the dye to the number that have not taken up the dye.
“Hemocytometry is a common technique in a lot of labs and while it has the advantage of accessibility, it also has disadvantages,” said Dr. Dinkelmann. She pointed out that the method is subjective, which results in low precision. It is also a time-consuming and labor-intensive method because of all the manual counting involved.
In contrast, flow cytometry is automated, significantly more objective, and enables the researcher to analyze cell viability in multiple cell populations simultaneously. “However, advanced techniques such as flow cytometry have not been more universally adopted for viability assays because they can be complex to use, expensive, and often require access to core facility systems.”