UPTAKE OF DOXORUBICIN FROM LOADED NANOPARTICLES IN MULTIDRUG-RESISTANT LEUKEMIC MURINE CELLS

Previous studies have clearly demonstrated that polyisobutylcyanoacryl ate (PIBCA) doxorubicin-loaded nanoparticles (NS-Dox PIBCA) can overco me the resistance of P388/ADR cells. In the present paper, we found th at overcoming multidrug resistance with the aid of doxorubicin (Dox) l oaded onto these nanoparticles was associated with an increased intrac ellular drug content. Indeed, after a 6-h incubation period, the amoun t of cell-associated drug was 5 times higher when the cells were incub ated with NS-Dox PIBCA as compared with free Dox. Further experiments, such as uptake studies in the presence of cytochalasin B or efflux st udies, indicated a possible mechanism of nanoparticle/cell interaction . These results suggested that nanoparticles did not enter the cells b y an endocytic process, in contrast to a previous hypothesis.