Limitations of the Fluorescent Probe Viability Assay

摘要

Cell viability commonly is determined flow cytometrically by the carboxyfluorescein diacetate (CFDA)/propidium iodide (PI) assay. CFDA is taken up by the viable cell and converted via cytoplasmic esterase-catalyzed hydrolysis to carboxyfluorescein (CF). CF fluorescence intensity is considered to be an index of cellular vigor. It is generally accepted that the viable cell excludes PI. PI uptake is indicative of irreversible cellular injury and presages cell death. The authors observe that, following incubation for 4 hr with 0.5 - 1.0 microMolar tributyltin (TBT), murine erythroleukemic cells (MELC) exhibit supranormal CF fluorescence and exclude PI. Apparent cell volume is unaltered. However, the rate of growth (cell duplication) of these cells is depressed, suggesting that supranormal CF fluorescence, even in the absence of PI uptake, is indicative of cellular perturbation. Furthermore, at higher TBT concentrations (>1.0,