Cationic Lipid Nanoparticles for miR-34A Delivery to Lung Cancer Cells: Comparative Evaluation of Plasmid DNA and Oligonucleotide Formulations.

MicroRNAs (miRNAs) are promising diagnostic biomarkers and therapeutic agents with therapeutic applications based on either miRNA mimics or antagonists. The objective of this study was to develop a cationic lipid nanoparticle (cLNP) system for the targeted delivery of miRNAs to cancer cells. We focused on the tumor-suppressor miR-34a, which is downregulated in many cancers, yet its clinical use remains limited by the lack of an efficient and safe delivery system. LNPs were prepared with solid lipids using the hot microemulsion method. Both plasmid DNA (P-miR34a) and oligonucleotide (O-miR34a) forms of miR-34a were complexed with cLNPs and characterized in terms of complex formation ability, particle size, and morphology. Cell proliferation and miR-34a expression levels were assessed after cLNP-miR-34a complexes were applied to normal and cancer cells. The miRNA-loaded complexes had a particle size of about 66 nm and a zeta potential value of +17.6 mV, while pDNA-loaded complexes had a particle size of approx. 114 nm and a zeta potential value of +3.9 mV. cLNPs showed dose-dependent cytotoxicity on normal and malignant cell lines. O-miR34a complexes significantly increased miR-34a levels in Calu1, HCC827 and H1299 cells, whereas P-miR34a complexes significantly enhanced expression in Calu1 and H1299 cells but not in HCC827. Our results showed that cLNP complexes, carrying the oligonucleotide form, successfully delivered miR-34a to all cell lines. Future studies should evaluate these formulations in in vivo models in order to evaluate their targeting specificity and therapeutic efficacy.