Polymeric nanoparticles for the delivery of miRNA to treat Chronic Obstructive Pulmonary Disease (COPD)

RNA interference (RNAi) based therapeutics are considered an endogenous mechanism for modulating gene expression. In addition, microRNAs (miRNAs) may be tractable targets for the treatment of Chronic Obstructive Pulmonary Disease (COPD). In this study miR146a was adsorbed onto poly (glycerol adipate-co-omega-pentadecalactone), PGA-co-PDL, nanoparticles (NPs) to reduce target gene IRAK1 expression. NPs were prepared using an oil-in-water single emulsion solvent evaporation method incorporating cationic lipid dioleoyl-trimethylammoniumpropane (DOTAP). This resulted in NPs of 244.80 +/- 4.40 nm at 15% DOTAP concentration, zeta potential (ZP) of + 14.8 +/- 0.26 mV and miR-146a (40 mu g/ml) maximum adsorption onto 15% DOTAP NPs was 36.25 +/- 0.35 mu g per 10 mg NP following 24 h incubation. Using the MTT assay, it was observed that over 75% at 0.312 mg/ml of A549 cells remained viable after 18 h exposure to cationic NPs at a concentration of 1.25 mg/ml. Furthermore, the in vitro release profile of miR-146a from loaded NPs showed a continuous release up to 77% after 24 h. Internalization of miR-146a loaded cationic NPs was observed in A549 cell lines using fluorescence and confocal microscopy. The miR146a delivered as miR-146a-NPs had a dose dependent effect of highest NPs concentrations 0.321 and 0.625 mg/ml and reduced target gene IRAK1 expression to 40%. In addition, IL-8 promoter reporter output (GFP) was dampened by miR-146a-NPs. In conclusion, miR-146a was successfully adsorbed onto PGA-co-PDL-DOTAP NPs and the miR-146a retained biological activity. Therefore, these results demonstrate the potential of PGA-co-PDL NPs as a delivery system for miR-146a to treat COPD.