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Exosomes, the smallest subgroup of extracellular vesicles, have been recognized as extracellular organelles that contain genetic and proteomic information for long distance intercellular communication. Exosome-based drug delivery is currently a subject of intensive research. Here, we report a novel strategy to produce nanoscale exosome-mimics (EMs) in sufficient quantity for gene delivery in cancer both in vitro and in vivo . Size-controllable EMs were generated at a high yield by serial extrusion of non-tumorigenic epithelial MCF-10A cells through filters with different pore sizes. siRNA was then encapsulated into the EMs by electroporation. Biosafety and uptake efficiency of the EMs were evaluated both in vitro and in vivo . The mechanism underlying their cellular endocytosis was also studied. [ABSTRACT FROM AUTHOR]

Abstract: Many cationic lipids have been developed for lipid-based nanoparticles (LNPs) for delivery of siRNA and microRNA (miRNA). However, less attention has been paid to “helper lipids”. Here, we investigated several “helper lipids” and examined their effects on the physicochemical properties such as particle size and zeta potential, as well as cellular uptake and transfection efficiency. We found that inclusion of oleic acid (OA), an unsaturated fatty acid, into the LNP formulation significantly enhanced the delivery efficacy for siRNA and miRNA. For proof-of-concept, miR-122, a liver-specific microRNA associated with many liver diseases, was used as a model agent to demonstrate the hepatic delivery efficacy both in tumor cells and in animals. Compared to Lipofectamine 2000, a commercial transfection agent, LNPs containing OA delivered microRNA-122 in a more efficient manner with a 1.8-fold increase in mature miR-122 expression and a 20% decrease in Bcl-w, a target of microRNA-122. In comparison with Invivofectamine, a commercial transfection agent specifically designed for hepatic delivery, LNPs containing OA showed comparable liver accumulation and in vivo delivery efficiency. These findings demonstrated the importance of “helper lipid” components of the LNP formulation on the cellular uptake and transfection activity of siRNA and miRNA. LNPs containing OA is a promising nanocarrier system for the delivery of RNA-based therapeutics in liver diseases. [Copyright &y& Elsevier]

Abstract: Lactosylated gramicidin-containing lipid nanoparticles (Lac-GLN) were developed for delivery of anti-microRNA-155 (anti-miR-155) to hepatocellular carcinoma (HCC) cells. MiR-155 is an oncomiR frequently elevated in HCC. The Lac-GLN formulation contained N-lactobionyl-dioleoyl phosphatidylethanolamine (Lac-DOPE), a ligand for the asialoglycoprotein receptor (ASGR), and an antibiotic peptide gramicidin A. The nanoparticles exhibited a mean particle diameter of 73nm, zeta potential of +3.5mV, anti-miR encapsulation efficiency of 88%, and excellent colloidal stability at 4°C. Lac-GLN effectively delivered anti-miR-155 to HCC cells with a 16.1- and 4.1-fold up-regulation of miR-155 targets C/EBPβ and FOXP3 genes, respectively, and exhibited significant greater efficiency over Lipofectamine 2000. In mice, intravenous injection of Lac-GLN containing Cy3-anti-miR-155 led to preferential accumulation of the anti-miR-155 in hepatocytes. Intravenous administration of 1.5mg/kg anti-miR-155 loaded Lac-GLN resulted in up-regulation of C/EBPβ and FOXP3 by 6.9- and 2.2-fold, respectively. These results suggest potential application of Lac-GLN as a liver-specific delivery vehicle for anti-miR therapy. [Copyright &y& Elsevier]

pH-sensitive liposomes are designed to promote efficient release of entrapped agents in response to low pH. In this study, novel pH-sensitive liposomes consisting of cationic/anionic lipid combinations are evaluated for intracellular drug and gene delivery. First, liposomes composed of egg phosphatidylcholine, dimethyldioctadecylammonium bromide (DDAB), cholesteryl hemisuccinate (CHEMS), and Tween-80 (25:25:49:1, mol/mol) were shown to stably entrap calcein at pH 7.4 and undergo rapid content release and irreversible aggregation under acidic pH. Compared to pH-sensitive liposomes incorporating dioleoylphosphatidylethanolamine, these liposomes showed improved retention of pH-sensitivity in the presence of serum. The folate receptor (FR), which is amplified in a wide variety of human tumors, could be targeted by incorporating 0.1 mol% folate-polyethyleneglycol-phosphatidylethanolamine (f-PEG-PE) into liposomes. f-PEG-PE has been shown to facilitate FR-mediated endocytosis of liposomes into KB human oral cancer cells, which express amplified FR. FR-targeted pH-sensitive liposomes produced increased cytosolic release of entrapped calcein, as shown by fluorescence microscopy, and enhanced cytotoxicity of entrapped cytosine-β-d-arabinofuranoside, as shown by an 11-fold reduction in the IC50 in KB cells, compared to FR-targeted non-pH-sensitive liposomes. Furthermore, FR-targeted pH-sensitive liposomes composed of DDAB/CHEMS/f-PEG-PE, combined with polylysine-condensed plasmid DNA, were shown to mediate FR-specific delivery of a luciferase reporter gene into KB cells in the presence of 10% serum. These findings suggest that cationic lipid-containing pH-sensitive liposomes, combined with FR targeting, are effective vehicles for intracellular drug and gene delivery. [Copyright &y& Elsevier]