CellTiter-Glo is a widely adopted laboratory assay, recognized for its robust performance and ease of use. Its primary function involves accurately quantifying viable cells within a sample. This method provides researchers with a straightforward and highly sensitive approach to assess cellular health and response to various experimental conditions. It has become a standard tool across numerous biological disciplines due to its reliability and efficiency in measuring cell viability.
How CellTiter-Glo Works
The scientific principle behind CellTiter-Glo centers on the measurement of adenosine triphosphate (ATP), a molecule found within metabolically active cells. ATP serves as the primary energy currency of the cell, making its presence a direct indicator of cellular viability and metabolic function. When the CellTiter-Glo Reagent is introduced to cell samples, it rapidly lyses cell membranes, releasing intracellular ATP.
The reagent contains recombinant luciferase, an enzyme from fireflies, along with its substrate, luciferin. Luciferase catalyzes a bioluminescent reaction where ATP reacts with luciferin in the presence of magnesium ions and oxygen. This enzymatic reaction generates a quantifiable light output. The intensity of this emitted light is directly proportional to the ATP concentration in the sample, which accurately reflects the number of viable cells, establishing a clear link between luminescence and cell count.
Key Applications of CellTiter-Glo
CellTiter-Glo finds extensive use in laboratories for studying cellular processes. A primary application involves measuring cell viability, allowing researchers to determine how many cells remain alive after different treatments. This helps in understanding the health and survival rate of cell populations.
The assay is also routinely employed to assess cell proliferation, which refers to the rate at which cells grow and divide over time. By quantifying ATP levels across multiple time points, scientists track cell growth curves and evaluate the impact of growth-promoting or inhibiting substances. CellTiter-Glo is widely used in cytotoxicity studies, where it helps determine the toxic effects of drugs, chemicals, or environmental factors on cells.
Understanding the Protocol Steps
Performing a CellTiter-Glo assay involves a straightforward and rapid protocol, suitable for high-throughput screening. Cells are typically cultured in multi-well plates, such as 96-well or 384-well formats. The CellTiter-Glo Reagent is added directly to the wells, eliminating the need for separate washing steps.
The plate is gently mixed on an orbital shaker for about two minutes to ensure cell lysis and reaction initiation. After ten minutes at room temperature, the stable luminescent signal is measured using a luminometer. This “add-mix-measure” approach contributes to its widespread adoption and efficiency.
Making Sense of the Results
Interpreting CellTiter-Glo assay results provides clear quantitative data. A higher luminescent signal, indicating more light, correlates with a greater number of viable, metabolically active cells. Conversely, a lower signal indicates fewer living cells, suggesting induced cell death or inhibited cellular growth due to experimental treatments.
Researchers compare luminescence units from treated samples to untreated control cells or vehicle controls. This comparative analysis quantifies specific effects, such as the percentage of cell viability remaining after exposure to a compound. The data provides robust and quantitative insights into how experimental conditions influence cell growth, metabolic activity, or cell survival.