CFSE

CFSE is a reagent useful for cell tracking, proliferation studies, and cell motility studies. After passively diffusing into cells, it is converted to a fluorescent carboxyfluorescin molecule as its acetate groups are cleaved by intracellular esterases. The fluorescent CFSE is retained inside the cell for extended periods, because the molecules forms stable covalent crosslinks with the intracellular proteins. At each cell division, the intensity of the CFSE fluorescence is halved. The peak excitation of the molecule is 494 nm and the peak emission is 521 nm and it may be used with standard fixatives containing formaldehyde and permeabilization buffers that contain saponin.