CFSE Fluorescent Cellular Stain

5-(and 6)-carboxyfluorescein diacetate, succinimidyl ester (5,6 CFDA,SE; CFSE), is a fluorogenic reagent which is frequently used in cell labeling and cell proliferation procedures. Non-fluorescent and moderately hydrophobic in its di-esterified form, 5,6 CFDA,SE easily penetrates lipid bi-layers of living cells and is quickly converted to the amine-reactive, green fluorescent form (CFSE) upon cleavage of the acetate groups by intracellular esterases. This highly fluorescent form is membrane-impermeant and is retained on and within the cells, while any excess CFSE probe is easily washed away in subsequent wash steps.