A cell viability assay based on monitoring respiration by optical oxygen sensing

A cell viability assay based on monitoring of the metabolic activity of living cells via their consumption of dissolved oxygen has been developed. It uses a microwell plate format and disposable phosphorescent sensor inserts incorporated into each sample. The wells are subsequently sealed from ambient oxygen using a layer of mineral oil, and periodically scanned from underneath with a simple fiber-optic phosphorescent phase detector. Thus, dissolved oxygen levels and time profiles of cell respiration can be determined noninvasively and compared to each other. The system was tested by monitoring the viability of the fission yeast Schizosaccharomyces pombe. In comparison with the conventional cell densitometry assay, the optical oxygen sensor method could reliably monitor lower numbers of cells (10(4)-10(5) vs 10(6)-10(7) cells/ml for densitometry), and accurately determine culture viability within 1 h. The assay was then applied to determine the viability of samples treated with toxic agents such as azide and in response to expression of a physiological inducer of cell death, the Bcl-2 family member Bak. The results obtained confirm that measurement of cell respiration by this assay can serve as a predictable, reliable, and fast method for high-throughput determination of cell viability and growth.