Cellular Uptake and Intracellular Trafficking of Antisense and siRNA Oligonucleotides

Abstract

Significant progress is being made concerning the development of oligonucleotides as therapeutic agents. Studies with antisense, siRNA, and other forms of oligonucleotides have shown promise in cellular and animal models and in some clinical studies. Nonetheless our understanding of how oligonucleotides function in cells and tissues is really quite limited. One major issue concerns the modes of uptake and intracellular trafficking of oligonucleotides, whether as ‘free’ molecules, or linked to various delivery moieties such as nanoparticles or targeting ligands. In this review we examine the recent literature on oligonucleotide internalization and subcellular trafficking in the context of current insights into the basic machinery for endocytosis and intracellular vesicular traffic.

Functional Delivery of siRNA by Disulfide-Constrained Cyclic Amphipathic Peptides

“…Numerous siRNA delivery systems have been explored, including lipid nanoparticles, cationic polymers, antibody constructs, and RNA aptamers. 5,6 While significant progress in siRNA delivery has been made with these various transfection agents, none are ideal and significant formulation/characterization barriers preclude their immediate clinical application.…”

The Role of micro RNAs in Breast Cancer Metastasis: Preclinical Validation and Potential Therapeutic Targets

“…Especially membrane antigen with high turnover rates and the tendency to trigger receptor-mediated endocytosis lead to a high accumulation of nucleic acid in endosomes. Intracellular routing and recycling pathways of vesicular cargo molecules are also subject to current research (209,210). Nevertheless, the biggest challenge is the entry of the therapeutic nucleic acids to its point of action -the cytoplasm or even the nucleus.…”

Nanoscale Small Interfering RNA Delivery Systems For Personalized Cancer Therapy

“…The siRNA delivery systems that have emerged during the last decade revolve around liposomal formulations [1][2][3][4][5][6][7][8][9][10], non-bilayer self-assembled polymeric nanoparticles [9], [11][12][13][14][15], and to a lesser extent, tertiary hybrid systems where lipids, polymers or solid cores are utilized [16][17][18]. The pharmacological effectiveness of oligonucleotidebased therapeutics depends on their cellular uptake, intracelular trafficking, endosomal release, and productive delivery to their target subcellular compartments [19,20]. The uptake of siRNA into the target cells is possible only if their highly polyanionic charges are hidden from the hydrophobic cell membrane bilayers.…”

“…Following cellular uptake, generally through endocytosis, the siR-NA-carrying nanoparticles and/or their cargo must escape the endosomes and enter the cytoplasm [19][20]. While the packaging of siRNA into nanoparticles via complexation promotes its delivery into the target cells, siRNA must eventually be released from the nanoparticles into the cytoplasm in order to trigger RNAi.…”

“…While the packaging of siRNA into nanoparticles via complexation promotes its delivery into the target cells, siRNA must eventually be released from the nanoparticles into the cytoplasm in order to trigger RNAi. siRNA can be delivered with a therapeutic intent using lipid-based delivery platforms such as stable nucleic acid lipid particles (SNALP) with a lipid bilayer containing cationic as well as fusogenic lipids and a diffusible PEG-lipid coat, polymers, cationic complexes, recombinant fusion proteins, conjugates, or polyconjugates [1][2][3], [7][8][9], [19][20], [25][26][27][28][29][30][31][32][33][34]. Several investigators have reported preclinical and early clinical proof of concept studies demonstrating that systemic delivery of an siRNA nanoparticle targeting a specific gene transcript can elicit biologic responses in vivo [11], [35][36][37][38][39][40][41][42].…”