Principle of the ViaStain™ PI Cell Cycle Assay
Cell cycle analysis is used to determine the proportion of cells in each stage of the cell cycle for a given cell population based on variations in DNA content. In this assay, each cell is stained with propidium iodide (PI), a fluorescent nuclear staining dye that intercalates with DNA. Because the dye cannot enter live cells, the cells are first fixed (with ethanol or methanol), and then stained with the cell cycle reagent. Cells preparing for division will contain increasing amounts of DNA and display proportionally increased fluorescence. Differences in fluorescence intensity are used to determine the percentage of cells in each phase of the cell cycle.