Enhanced gene delivery efficiency of cationic liposomes coated with PEGylated hyaluronic acid for anti P-glycoprotein siRNA: A potential candidate for overcoming multi-drug resistance

RNA interference is an effective method to achieve highly specific gene regulation. However, the commonly used cationic liposomes have poor biocompatibility, which may lead to systematic siRNA delivery of no avail. PEGylation is a good strategy in shielding the positive charge of cationic liposomes, but the enhanced serum stability is often in company with compromised cellular uptake and endosome escape. In this study, PEG was covalently linked to negatively charged hyaluronic acid and it was used to coat the liposome-siRNA nanoparticles. The resulting PEG-HA-NP complex had a diameter of 188.6 ± 10.8 nm and a dramatically declined zeta-potential from +34.9 ± 4.0 mV to −18.2 ± 2.2 mV. Owing to the reversed surface charge, PEG-HA-NP could remain stable in fetal bovine serum (FBS) to up to 24 h. In contrast with normal PEGylation, hyaluronic acid and PEG co-modified PEG-HA-NP provided comparable cellular uptake and P-glycoprotein downregulation efficacy in MCF-7/ADR cells compared with Lipofectamine RNAiMAX and naked NP regardless of its anionic charged surface. Because of its good biocompatibility in serum, PEG-HA-NP possessed the best tumor accumulation, cellular uptake and subsequently the strongest P-glycoprotein silencing capability in tumor bearing mice compared with naked NP and HA-NP after i.v. injection, with a 34% P-glycoprotein downregulation. Therefore, PEG-HA coated liposomal complex was demonstrated to be a promising siRNA delivery system in adjusting solid tumor P-glycoprotein expression, which may become a potential carrier in reversing MDR for breast cancer therapy.

PEGylated hyaluronic acid (PEG-HA) was synthesized and employed to coat the cationic liposome-siRNA complex through electrostatic interaction to form PEG-HA-NP. Due to a reversed surface charge, PEG-HA-NP could keep stable in fetal bovine serum (FBS). In vitro studies demonstrated that PEG-HA-NP had two cell internalization pathways and it had comparable P-glycoprotein downregulation efficacy with Lipofectamine RNAiMAX. In vivo experiments illustrated that PEG-HA-NP possessed the best tumor accumulation, cellular uptake, and P-glycoprotein downregulation capability in tumor bearing mice compared with naked NP and HA-NP after systemic administration. Overall, PEG-HA-NP proved itself an efficient siRNA carrier and the ability of downregulating P-glycoprotein made it a potential candidate to overcome multi-drug resistance.292