Glucan particles for selective delivery of siRNA to phagocytic cells in mice

Abstract

Phagocytic macrophages and dendritic cells are desirable targets for potential RNAi (RNA interference) therapeutics because they often mediate pathogenic inflammation and autoimmune responses. We recently engineered a complex 5 component glucan-based encapsulation system for siRNA (small interfering RNA) delivery to phagocytes. In experiments designed to simplify this original formulation, we discovered that the amphipathic peptide Endo-Porter forms stable nanocomplexes with siRNA that can mediate potent gene silencing in multiple cell types. In order to restrict such gene silencing to phagocytes, a method was developed to entrap siRNA-Endo-Porter complexes in glucan shells of 2-4 μm diameter in the absence of other components. The resulting glucan particles containing fluorescently labelled siRNA were readily internalized by macrophages, but not other cell types, and released the labelled siRNA into the macrophage cytoplasm. Intraperitoneal administration of such glucan particles containing siRNA-Endo-Porter complexes to mice caused gene silencing specifically in macrophages that internalized the particles. These results from the present study indicate that specific targeting to phagocytes is mediated by the glucan, whereas Endo-Porter peptide serves both to anchor siRNA within glucan particles and to catalyse escape of siRNA from phagosomes. Thus we have developed a simplified siRNA delivery system that effectively and specifically targets phagocytes in culture or in intact mice.

Functional RNA delivery targeted to dendritic cells by synthetic nanoparticles

“…Basha et al noted that from four ionizable cationic lipids, lipidnanoparticles based on 1,2-dilinoleyl-4-(2-dimethylaminoethyl)- [1,3]-dioxolane were the most efficient for cytosolic delivery of siRNA in murine macrophages and DCs [91]. The amphipathic peptide Endo-Porter forms stable complexes with siRNA and was also successfully delivered to macrophages in glucan shells [92]. A cationic nona-d-arginine construct was applied together with a DC-targeting ligand to deliver siRNA for knockdown of dengue virus replication in macrophages and DCs [93].…”

1,3-Beta-Glucans: Drug Delivery and Pharmacology

“…The -glucan on the microspheres serves as a specific target for uptake by immune cells such as macrophages and dendritic cells [40]. Glucan microspheres can be used for delivering various payloads such as proteins [19], DNA [40], siRNA [16,41] and small molecules [39]. Typically small molecules are not easily entrapped within these glucan microspheres and hence the use of nanoparticles is necessary.…”

“…Polynucleotides have found several applications in drug delivery as active agents due to their therapeutic effects [16,41,49]. One of the challenges faced by polynucleotide delivery is their rapid degradation in vivo.…”

“…When extracted 1,3--glucans are administered to animals or humans, they recruit macrophages and stimulate the immune system through a similar mechanism [8,9]. This result has been utilized for various pharmacological applications including cancer inhibition [10][11][12][13][14][15][16][17], infection resistance [18][19][20][21] and wound healing [22][23][24]. Current research is focusing on combining the structural properties of 1,3--glucans with the pharmacological ones to further enhance the efficacy of hybrid systems thus created.…”

Recent advances in oral vaccine development

“…93,94,[98][99][100][101][102][103] Based on the in situ layer-by-layer synthesis through electrostatic interactions, the group of Soto initially engineered yeast cell wall particles for DNA delivery. 104 This encapsulation strategy enables a high nucleic acid capacity and delivery, in addition to the oral bioavailability of β-glucan particles and their inherent β-glucan receptor targeting capacity toward APCs.…”