title: Enhanced intercellular retention activity of novel pH-sensitive polymeric micelles in wild and multidrug resistant MCF-7 cells.
abstract: OBJECTIVE
  The purpose of this work was to demonstrate the advantage of using pH-sensitive polymeric mixed micelles (PHSM) composed of poly(L: -histidine) (polyHis)/poly(ethylene glycol) (PEG) and poly(L: -lactic acid) (pLLA)/PEG block copolymers with folate conjugation to increase drug retention in wild-type and MDR tumor cells.
  
  
  METHODS
  Both wild-type and multidrug resistant (MDR) human breast adenocarcinoma (MCF-7) cell lines were used to investigate the accumulation and elimination of doxorubicin (DOX), PHSM with folate (PHSM/f), and pH-insensitive micelles composed of pLLA/PEG block copolymer with folate (PHIM/f).
  
  
  RESULTS
  Cells treated with PHSM/f showed decelerated elimination kinetics compared to cells treated with PHIM/f. MDR cells treated with drug-containing PHSM/f for 30 min retained 80% of doxorubicin (DOX) even after incubation for 24 h in the absence of drug. On the other hand, cells treated with drug-containing PHIM/f retained only 40% of DOX within the same period of time. Flow cytometry and confocal microscopy confirmed these results.
  
  
  CONCLUSIONS
  Cellular entry of the micelles occurred via receptor-mediated endocytosis using folate receptors. The pH-induced destabilization of PHSM/f led to rapid distribution of drug and polymer throughout the cells, most likely due to polyHis-mediated endosomal disruption. This reduced the likelihood of drug efflux via exocytosis from resistant tumor cells.
authors: Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, 421 Wakara Way, Suite 315, Salt Lake City, UT 84108, USA.
authors: Ghazal
authors: G
authors: Mohajer
authors: Eun Seong
authors: ES
authors: Lee
authors: You Han
authors: YH
authors: Bae
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000008:administration & dosage / Q000493:pharmacokinetics; D016503:Drug Delivery Systems; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D016650:Fluorescein-5-isothiocyanate; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008823:Micelles; D011108:Polymers / Q000493:pharmacokinetics*
chemical_list: D008823:Micelles; D011108:Polymers; D004317:Doxorubicin; D016650:Fluorescein-5-isothiocyanate