Cell proliferation is an increase in the number of cells resulting from the normal, healthy process by which cells grow and divide. In this regard, cell proliferation can be a good indicator of general cell health. Cells that are subject to a variety of disease states may exhibit different rates of proliferation than normal cells. Therefore, measuring rates of cell proliferation between different cell populations may provide insight into the relative health of those cells.
There are several methods available to measure cell proliferation rates. One method is to measure the overall metabolic activity inside a cell. Several dyes are available that can permeabilize a cell and react with certain enzymes and other factors and form a colored end-product which can be easily detected. One such dye, MTT, is a well-published molecule that produces a distinct purple color when added to proliferating cells. Another dye, WST-1, provides a similar color change in proliferating cells, but has the advantage of a single-step method that eliminates the detergent solubilization step required for MTT.
Fluorescence dyes are also available to measure rates of cell proliferation. These dyes have the advantage of providing greater sensitivity than colorimetric dyes, which can be a benefit when measuring smaller differences in cell proliferation rates between different cell populations.
Besides overall metabolic activity, cell proliferation may be measured by examining one or more specific markers within a cell. A well-published example is the BrdU incorporation assay. In this assay, cells are treated with BrdU, a thymidine analog that is incorporated into the DNA during cell proliferation. The BrdU can be detected with a special antibody, and high rates of BrdU incorporation correlate with high cell proliferation rates. Another such marker is proliferating cell nuclear antigen (PCNA), which promotes DNA replication in actively proliferating cells.
In addition to measuring relative rates of proliferation between different cells, cell proliferation assays can be useful for determining the effects of compounds that may have the potential for increasing or decreasing cell proliferation rates.