Novel Endosomolytic Poly(amido amine) Polymer Conjugates for Systemic Delivery of siRNA to Hepatocytes in Rodents and Nonhuman Primates

Abstract

The application of small interfering (si)RNAs as potential therapeutic agents requires safe and effective methods for their delivery to the cytoplasm of the target cells and tissues. Recent studies have shown significant progress in the development of targeting reagents that facilitate the recognition of, and siRNA delivery to, specific cell types. Among recently reported delivery approaches, polymers with amphipathic properties have been used to enable endosome escape and cytosolic delivery. Here, we describe a linear amphipathic poly(amido amine) polymer conjugate system for the efficient siRNA delivery in vitro and in vivo. This polymer contains a novel amine bearing bis-acrylamide monomer designed for increasing amine density, which resulted in substantial improvement in liver uptake and RNAi activity compared to our previously reported poly(amido amine disulfide) polymer.1 The activity for this liver targeted delivery system was demonstrated in rodents and nonhuman primates.

Liver X receptor α (LXRα/NR1H3) regulates differentiation of hepatocyte-like cells via reciprocal regulation of HNF4α

“…The addition of NR1H3 agonists into differentiation cocktails might also be beneficial for the generation of functional hepatocyte-like cells from other stem cell resources and for further studies of hepatocyte transplantation in end-stage liver disease. Finally, it is also possible to accelerate liver regeneration in vivo by liver-specific target delivery of NR1H3 agonists, such as to package agonists into liver-specific vehicles [54,55].…”

Covalent Strategies for Targeting Messenger and Non-Coding RNAs: An Updated Review on siRNA, miRNA and antimiR Conjugates

“…Other polymers with endosomolytic capabilities have been proven to be efficient vehicles for siRNA delivery. Poly(amido amine) (PAA)-based polymer derivatives [ 94 , 95 ] containing cationic amine pendent groups were modified with MAA and poly(ethylene glycol), respectively as amine-masking groups in order to reduce their apparent toxicities. These polymers were easily tuned by introducing additional functional groups to increase their abilities to promote cellular uptake and red blood cell (RBC) lysis activity.…”

“…PAA polymers were firstly functionalized with an imidazole residue in order to favour the proton-sponge mechanism [ 96 ]. Hydrophobic lipid tails and the triantennary GalNAc residue were also introduced to increase the solubility of the polymer and recognize the ASGR receptor, respectively [ 94 , 95 ]. The strategy for introducing the therapeutic siRNA was based on using reducible disulphide bonds between the PAA polymers and the corresponding siRNA oligonucleotide.…”

“…In light of these results, a good number of strategies have been accomplished to improve biodegradability rates in vivo and therefore reduce the apparent cytotoxicity of cationic polymers without affecting the silencing activity. These strategies have been focused on introducing additional moieties to the PAA polymer and can be summarized as follows: (i) Derivatization with disulphide linkers [ 95 ]; (ii) The use of mixtures of cystamine bis-acrylamide [ 94 ]; (iii) Introduction of polypeptides based on a mixture of l -ornithine and l -phenylalanine (in a ratio of 4:1) [ 97 ] and (iv) The use of post-polymerization approaches with the aim of modifying siRNA-polymer conjugates with acetic acid, heterocycles with low pK a and acid cleavable acetal linkers [ 98 ].…”

Bioconjugates for targeted delivery of therapeutic oligonucleotides

“…Scientists at Merck & Co. Inc have focused on optimization of the carrier polymer in order to enhance the efficacy and safety of the delivery system [71-73]. The amphipathic PBAVE polymer in original DPCs may continue to interact with non-endosomal membranes after endosomal release and then cause side effects.…”