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BackgroundLung cancer is the primary cause of cancer-related death worldwide. A redox-sensitive nanocarrier system was developed for tumor-targeted drug delivery and sufficient drug release of the chemotherapeutic agent paclitaxel (PTX) for improved lung cancer treatment.MethodsThe redox-sensitive nanocarrier system constructed from a hyaluronic acid-disulfide-vitamin E succinate (HA-SS-VES, HSV) conjugate was synthesized and PTX was loaded in the delivery system. The physicochemical properties of the HSV nanoparticles were characterized. The redox-sensitivity, tumor-targeting and intracellular drug release capability of the HSV nanoparticles were evaluated. Furthermore, in vitro and in vivo antitumor activity of the PTX-loaded HSV nanoparticles was investigated in a CD44 over-expressed A549 tumor model.ResultsThis HSV conjugate was successfully synthesized and self-assembled to form nanoparticles in aqueous condition with a low critical micelle concentration of 36.3 μg mL−1. Free PTX was successfully entrapped into the HSV nanoparticles with a high drug loading of 33.5% (w/w) and an entrapment efficiency of 90.6%. Moreover, the redox-sensitivity of the HSV nanoparticles was confirmed by particle size change of the nanoparticles along with in vitro release profiles in different reducing environment. In addition, the HA-receptor mediated endocytosis and the potency of redox-sensitivity for intracellular drug delivery were further verified by flow cytometry and confocal laser scanning microscopic analysis. The antitumor activity results showed that compared to redox-insensitive nanoparticles and Taxol®, PTX-loaded redox-sensitive nanoparticles exhibited much greater in vitro cytotoxicity and apoptosis-inducing ability against CD44 over-expressed A549 tumor cells. In vivo, the PTX-loaded HSV nanoparticles possessed much higher antitumor efficacy in an A549 mouse xenograft model and demonstrated improved safety profile. In summary, our PTX-loaded redox-sensitive HSV nanoparticles demonstrated enhanced antitumor efficacy and improved safety of PTX.ConclusionThe results of our study indicated the redox-sensitive HSV nanoparticle was a promising nanocarrier for lung cancer therapy.

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Currently, the most prominent barrier to the success of orally delivered paclitaxel (PTX) is the extremely limited bioavailability of delivered therapeutic. In light of this issue, an amphiphilic sulfhydrylated N-deoxycholic acid-N,O-hydroxyethyl chitosan (TGA-DHC) was synthesized to improve the oral bioavailability of PTX. First, TGA-DHC demonstrated substantial loading of PTX into the inner hydrophobic core. A desirable enhancement in the bioavailability of PTX by TGA-DHC was verified by pharmacokinetic studies on rats against Taxol and non-sulfhydrylated DHC micelles. Moreover, cellular uptake studies revealed significant accumulation of TGA-DHC micelles encapsulating PTX or rhodamine-123 into Caco-2 cells via clathrin/caveolae-mediated endocytosis and inhibition of P-gp efflux of substrates. The results of the Caco-2 transport study further confirmed the mechanistic basis of TGA-DHC efficacy; which was attributed to permeabilized tight junctions, clathrin-mediated transcytosis across the endothelium, and inhibition of P-gp. Finally, in vitro mucoadhesion investigations on freshly excised rat intestine intuitively confirmed increased intestinal retention of drug-loaded TGA-DHC through thiol-mediated mucoadhesion. TGA-DHC has demonstrated the capability to overcome what is perhaps the most prominent barrier to oral PTX efficacy, low bioavailability, and serves as a prominent platform for oral delivery of P-gp substrates.