Pulmonary siRNA Delivery with Sophisticated Amphiphilic Poly(Spermine Acrylamides) for the Treatment of Lung Fibrosis

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 20; no. 22; pp. e2308775 - n/a
• Main Authors: Adams, Friederike, Zimmermann, Christoph M., Baldassi, Domizia, Pehl, Thomas M., Weingarten, Philipp, Kachel, Iris, Kränzlein, Moritz, Jürgens, David C., Braubach, Peter, Alexopoulos, Ioannis, Wygrecka, Malgorzata, Merkel, Olivia M.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.05.2024
• Subjects: Acrylamides - chemistry; Animals; Biocompatibility; Copolymerization; Copolymers; Fibrosis; Gene expression; Humans; Hydrophobicity; Lipids; Lung - metabolism; Lung - pathology; lung fibrosis; Lungs; poly(spermine acrylamide); Polymers; Polymers - chemistry; post‐polymerization functionalization; pulmonary delivery; Pulmonary Fibrosis - drug therapy; Pulmonary Fibrosis - pathology; Pulmonary Fibrosis - therapy; Receptors; Ribonucleic acid; RNA; RNA, Small Interfering; siRNA delivery; Spermine - chemistry; Spermine - pharmacology; siRNA delivery; pulmonary delivery; poly(spermine acrylamide); post‐polymerization functionalization; lung fibrosis
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202308775

RNA interference (RNAi) is an efficient strategy to post‐transcriptionally silence gene expression. While all siRNA drugs on the market target the liver, the lung offers a variety of currently undruggable targets, which can potentially be treated with RNA therapeutics. To achieve this goal, the synthesis of poly(spermine acrylamides) (P(SpAA) is reported herein. Polymers are prepared via polymerization of N‐acryloxysuccinimide (NAS) and afterward this active ester is converted into spermine‐based pendant groups. Copolymerizations with decylacrylamide are employed to increase the hydrophobicity of the polymers. After deprotection, polymers show excellent siRNA encapsulation to obtain perfectly sized polyplexes at very low polymer/RNA ratios. In vitro 2D and 3D cell culture, ex vivo and in vivo experiments reveal superior properties of amphiphilic spermine‐copolymers with respect to delivery of siRNA to lung cells in comparison to commonly used lipid‐based transfection agents. In line with the in vitro results, siRNA delivery to human lung explants confirm more efficient gene silencing of protease‐activated receptor 2 (PAR2), a G protein‐coupled receptor involved in fibrosis. This study reveals the importance of the balance between efficient polyplex formation, cellular uptake, gene knockdown, and toxicity for efficient siRNA delivery in vitro, in vivo, and in fibrotic human lung tissue ex vivo. Amphiphilic, cationic poly(spermine acrylamides) are synthesized via facile radical polymerization of N‐acryloxysuccinimide and N‐decylacrylamide followed by post‐polymerization functionalization with spermine. In vitro 2D and 3D cell culture, ex vivo and in vivo experiments reveal superior properties of spermine‐copolymers in delivery of siRNA to lung cells demonstrating a perfect balance between efficiency and toxicity while outperforming commonly used non‐viral transfection agents.