Intracellular uptake and trafficking of Pluronic micelles in drug-sensitive and MDR cells: Effect on the intracellular drug localization

✍ Scribed by Natalya Rapoport; Alexander Marin; Yi Luo; Glenn D. Prestwich; Md. Muniruzzaman

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 599 KB
• Volume: 91
• Category: Article
• ISSN: 0022-3549
• DOI: 10.1002/jps.10006

✦ Synopsis

The intracellular uptake and localization of a ¯uorescently labeled Pluronic P-105 in HL-60 leukemia cells and in A2780 drug-sensitive and A2780/ADR MDR ovarian carcinoma cells were characterized by ¯ow cytometry and ¯uorescence microscopy. Pluronic P-105 molecules were labeled with a pH-sensitive ¯uorescent label, 5-(and 6-)carboxy-2 H 7 H -dichloro¯uorescein. The ¯uorescence intensity of labeled Pluronic was about twofold higher at pH 7.4 than at pH 5.5. At Pluronic concentrations exceeding the critical micelle concentration (cmc), ¯ow cytometry histograms manifested bimodal distribution of cell ¯uorescence for all types of cells. Cell population characterized by higher ¯uorescence intensity presumably resulted from Pluronic transfer from the acidic environment of cytoplasmic vesicles (endosomes or lysosomes) into the neutral environment of the cytoplasm and cell nuclei, which suggested the permeabilization of the membranes of acidic vesicle by Pluronic molecules. For the MDR cells, the bimodal distribution of cell ¯uorescence was already observed at very low Pluronic concentrations in the incubation medium (i.e., below the cmc). The data suggest that the membranes of acidic vesicles of MDR cells are more susceptible to the action of polymeric surfactants than those of drug-sensitive cells. Permeabilization of acidic vesicles had a dramatic effect on the intracellular traf®cking of drugs: when delivered in PBS, the anthracyclin drug ruboxyl (Rb) sequestered in cytoplasmic vesicles and was excluded from cell nuclei; however, when delivered in Pluronic micelles, drug accumulated in cell nuclei. Drug uptake from/with Pluronic micelles was substantially enhanced by ultrasound. These ®ndings suggest that the nuclear accumulation of drugs internalized via ¯uid-phase endocytosis can be enhanced by the application of Pluronic micelles and can be further augmented by ultrasonic irradiation.