A novel nonviral gene delivery system: multifunctional envelope-type nano device

Irf5 siRNA-loaded biodegradable lipid nanoparticles ameliorate concanavalin A-induced liver injury

RNA interference-based gene silencing drugs are attracting attention for treating various diseases. Lipid nanoparticles (LNPs) are carriers that efficiently deliver small interfering RNA (siRNA) to the cytoplasm of target cells. Recently, we developed potent and well-tolerated biodegradable LNPs with asymmetric ionizable lipids. Here, we evaluated the effect of LNPs on immune cells in mice. After intravenous administration, LNPs were efficiently incorporated into several tissue-resident macrophages, including liver macrophages, through an apolipoprotein E (ApoE)-independent mechanism. Administration of LNP-encapsulated siRNA against Irf5, encoding the transcription factor critical for inflammatory responses, sharply reduced its expression in macrophages in vivo, and persisted for as long as 7 days. The therapeutic potential of Irf5 siRNA-loaded LNPs in inflammatory diseases was tested in a concanavalin A (Con A)-induced hepatitis model, whose pathogenic mechanisms are dependent on cytokine secretion from macrophages. We found that Con A-induced liver injury was significantly attenuated after LNP injection. Serum aspartate transaminase, alanine aminotransferase, and inflammatory cytokine levels were significantly reduced in mice injected with Irf5 siRNA-loaded LNPs compared to those injected with control siRNA-loaded LNPs. Our results suggest that administering biodegradable LNPs to deliver siRNA is a promising strategy for treating inflammatory disorders.

Development of a low toxicity, effective pDNA vector based on noncovalent assembly of bioresponsive amino-β-cyclodextrin:adamantane-poly(vinyl alcohol)-poly(ethylene glycol) transfection complexes

A host:guest-derived gene delivery vector has been developed, based on the self-assembly of cationic β-CD derivatives with a poly(vinyl alcohol) (MW 27 kDa) (PVA) main chain polymer bearing poly(ethylene glycol) (MW 750) (PEG) or MW 2000 PEG and acid-labile adamantane-modified (Ad) grafts through an acid-sensitive benzylidene acetal linkage. These components were investigated for their ability to promote supramolecular complex formation with pDNA using two different assembly schemes, involving either precomplexation of the pendent Ad-PVA-PEG polymer with the cationic β-CD derivatives before pDNA condensation (method A) or pDNA condensation with the cationic β-CD derivatives prior to addition of Ad-PVA-PEG to engage host:guest complexation (method B). The pendent polymers were observed to degrade under acidic conditions while remaining intact for more than 5 days at pH 7. HeLa cell culture data show that these materials have 10(3)-fold lower cytotoxicities than 25 kDa bPEI while maintaining transfection efficiencies that are superior to those observed for this benchmark cationic polymer transfection reagent when the method A assembly scheme is employed. These findings suggest that degradable cationic polymer constructs employing multivalent host:guest interactions may be an effective and low-toxicity vehicle for delivering nucleic acid cargo to target cells.