cell viability

What is cell viability

Cell viability is the measure of the proportion of living, metabolically functional cells relative to the total number of cells in a sample. It reflects how many cells retain an intact membrane and the ability to survive, and it is a fundamental parameter in cell culture, toxicity testing, and bioprocessing.

According to protocols published in Current Protocols in Immunology, the dye exclusion test relies on the principle that live cells have intact membranes that exclude dyes such as trypan blue, whereas dead cells absorb them.

How cell viability analysis works

The most traditional method is trypan blue exclusion: a cell suspension is mixed with the dye and examined under a microscope. Viable cells keep a clear cytoplasm, while non-viable cells stain blue. Viability is calculated by dividing the number of live cells by the total counted.

Beyond trypan blue, methods using fluorescent dyes, metabolic assays (such as MTT), and flow cytometry are available, each suited to different levels of sensitivity and sample throughput.

Automated instruments

Dedicated analyzers automate counting and viability calculation, reducing manual errors. The Vi-CELL BLU by Beckman Coulter is one example that automates trypan blue exclusion, delivering results as percentage, concentration, and cell count with carousel or 96-well plate processing.

Applications in laboratory and industry

Cell viability is critical in biomedical research, drug development, biotechnology, and advanced therapy production. Monitoring viability ensures cultures are healthy before experiments, controls quality in bioprocesses, and validates compound safety in cytotoxicity testing.

What is considered good cell viability?

For healthy log-phase cultures, viability is typically at least 95%. Much lower values may indicate cellular stress, contamination, or inadequate culture conditions.

What is the difference between viability and cell proliferation?

Viability assesses whether cells are alive at a given moment; proliferation measures the ability of cells to divide and increase in number over time. They are complementary parameters.

Why automate cell viability analysis?

Automation reduces operator variability, speeds up processing, uses less sample, and improves data traceability, making it advantageous for high-demand laboratories.