Novel Mixed Polymeric Micelles for Enhancing Delivery of Anticancer Drug and Overcoming Multidrug Resistance in Tumor Cell Lines Simultaneously

BSTRACT Purpose To evaluate novel mixed polymeric micelles based on monomethoxy poly(ethylene glycol)-poly(D,L-lactic acid) (mPEG-PLA) and Pluronic L61 for delivery of paclitaxel (PTX) to circumvent unfavorable effects resulting from Cremophore EL in Cremophore EL-based PTX formulation and overcoming multidrug resistance (MDR) in tumor cells at the same time. Methods PTX-loaded plain micelles and mixed micelles were prepared and characterized by determining PTX release in vitro , MDR reversal effect in human breast cancer MDR MCF-7/ADR cell sublines and pharmacokinetics in vivo . Results Both PTX-loaded plain micelles and mixed micelles had similar in vitro release profile. Mixed micellar PTX significantly reduced IC 50 of PTX in MCF-7/ADR cells compared to free PTX and plain micellar PTX, and mixed micelles substantially enhanced cellular accumulation of R 123 in MCF-7/ADR cells compared to free R123 and plain micelles. PTX-loaded mixed micelles with lower content of L61 exhibited comparable cytotoxicity to that observed with Cremophore EL-based PTX formulation in inhibiting the growth of MCF-7/ADR cells. Moreover, plain micelles and mixed micelles retained the pharmacokinetic characteristics of PTX in rats compared with Cremophore EL-based PTX formulation. Conclusion This study suggested that the mixed micelles could enhance delivery of PTX and cell-killing effect for MDR MCF-7/ADR cells.