New Cell Viability Assay Streamlines Compound Testing

Professor emeritus of biochemistry Paul Kitos and his lab staff have developed a virtually problem-free cell viability assay with great licensing potential. It is a homogeneous tetrazolium-reduction assay for determining the number of living cells in a multi-well culture. It does so by measuring an enzyme found only in living or "viable" cells. The primary assay developer is biological sciences research associate Gale Haslam. Her co-researchers are Diane Wyatt, president of Wyatt Consulting, and professor of molecular biosciences, Mark Richter.

One of the assay's greatest assets is its sensitivity. In fact, it is more sensitive than any other commercially available cell viability assay, except those that use fluorescence detection. Depending on the cell line, it can quantify as few as 300 cells. Also, though assays of this kind are normally conducted at room temperature, this assay's sensitivity is enhanced at 37^° C. The assay can be performed in as few as 5 minutes, depending on cell density in a sample.

Unlike its competitors, this inexpensive assay is useful for both small and large cell populations, even in different wells of the same plate. It is equally applicable to adherent and suspension cell cultures and to both single cells and cell aggregates, alone or in mixed populations.

Another thing that sets this assay apart is that the resulting color development is linear with respect to both the number of cells per well and the length of the assay. Also, it isn't affected by different concentrations of serum in the medium and works with or without phenol red in the medium.

Suitable for high-throughput cell viability screening, the assay can be used to evaluate both inhibition and stimulation of cell proliferation. It has been tested on many different kinds of animal and insect cell lines, all of which have responded well to it. With appropriate software, colorimetric data can be automatically processed to yield viable cell numbers as well as information about the assay kinetics.

"It's always so simple, quick and reliable," Kitos said. "The assay can be used to measure a variety of things. You're limited only by your ingenuity in adapting it." •