Pluronic mixed micelles overcoming methotrexate multidrug resistance: in vitro and in vivo evaluation

A Pluronic polymeric mixed micelle delivery system was developed in this study by using Pluronic P105 and F127 block copolymers to encapsulate the antitumor compound, methotrexate (MTX). The MTX-loaded Pluronic P105/F127 mixed micelle exhibited the spherical shape with about 22 nm in diameter, high encapsulation efficiency (about 85%) and pH-dependent in vitro drug release. In this study, A-549 and KBv cell lines were selected as multidrug resistance tumor cell models, while H-460 and KB cell lines were chosen as sensitive tumor cells. The MTX-loaded Pluronic P105/F127 mixed micelle exhibited significant higher in vitro cytotoxicity in multidrug resistant tumor cells than that of control (MTX injection) mainly because of higher cellular uptake of MTX. The pharmacokinetic studies indicated that the Pluronic micelles significantly prolonged systemic circulation time of MTX compared to MTX injection. Moreover, a much stronger antitumor efficacy in KBv tumor xenografts nude mice was observed in the MTX-loaded Pluronic P105/F127 mixed micelle group, than MTX. Collectively, Pluronic P105/F127 mixed micelles could significantly enhance the antitumor activity of MTX and might be a promising drug delivery platform for multidrug resistance modulation.