Efficient megalin targeted delivery to renal proximal tubular cells mediated by modified-polymyxin B-polyethylenimine based nano-gene-carriers

Abstract

Non-viral vectors have attracted great interest, as they are simple to prepare, easy to modify and relatively safe, compared to viral vectors. Kidney-targeted gene delivery systems depict a promising technology to improve drug efficacy in renal diseases treatments. In order to develop a novel kidney-targeted gene delivery system, we synthesized polyamine-PEI conjugates using polymyxin B as ligand and investigated their potential targeting efficiency. After grafting either PEI₂₅ kDa or PEI₁₀ kDa with polymyxin B through amidation reaction, the modified-polymyxin-PEI/DNA-nanoplexes were produced via electrostatic attraction between the cationic polymers and EGFP plasmid. The properties of modified polymers including size, surface charge density, DNA condensation ability, buffering capacity and cytotoxicity were evaluated. Results revealed that the average size of -modified-polymyxin- PEI₂₅kDa was about 143-180nm and modified-polymyxin-PEI₁₀kDa 115-194nm. The zeta potentials were in the range of 16.4±1.87 to 23.43±1.25mV and 11.3±1.4 to 19.3±2.1mV for conjugates based on PEI₂₅ and PEI₁₀ respectively. The AFM images revealed that the complexes were spherical and nano-sized at C/P=4. The buffering capacity of both PEI 10 and 25kDa increased as the percentage of polymyxin B grafting increased. In vitro study demonstrated that modified-polymyxin-PEI conjugates could remarkably improve the gene transfection efficiency to kidney cells. The transfection efficiency of the polyplexes was dependent on the weight ratio of ligand in the formulation (~12 and 8 fold increase for PEI₂₅ and PEI₁₀kDa, respectively) and was significantly higher than that of unmodified PEIs/DNA nanoparticles. These results suggest that modified-polymyxin-PEI /DNA nanoparticles can effectively target megalin-expressing kidney cells and show improved transfection efficiency and low cytotoxicity in In vitro and In vivo studies. Animal studies confirmed the in vivo study. Thus, these conjugates can be considered as a safe and efficient non-viral therapeutic therapy vector for kidney diseases.

Keywords: Gene delivery; Megalin; Polyethylenimine; Polymyxin B; Renal targeting.