Block catiomers with flanking hydrolyzable tyrosinate groups enhance in vivo mRNA delivery via π–π stacking-assisted micellar assembly

Abstract

Messenger RNA (mRNA) therapeutics have recently demonstrated high clinical potential with the accelerated approval of SARS-CoV-2 vaccines. To fulfill the promise of unprecedented mRNA-based treatments, the development of safe and efficient carriers is still necessary to achieve effective delivery of mRNA. Herein, we prepared mRNA-loaded nanocarriers for enhanced in vivo delivery using biocompatible block copolymers having functional amino acid moieties for tunable interaction with mRNA. The block copolymers were based on flexible poly(ethylene glycol)-poly(glycerol) (PEG-PG) modified with glycine (Gly), leucine (Leu) or tyrosine (Tyr) via ester bonds to generate block catiomers. Moreover, the amino acids can be gradually detached from the block copolymers after ester bond hydrolyzation, avoiding cytotoxic effects. When mixed with mRNA, the block catiomers formed narrowly distributed polymeric micelles with high stability and enhanced delivery efficiency. Particularly, the micelles based on tyrosine-modified PEG-PG (PEG-PGTyr), which formed a polyion complex (PIC) and π–π stacking with mRNA, displayed excellent stability against polyanions and promoted mRNA integrity in serum. PEG-PGTyr-based micelles also increased the cellular uptake and the endosomal escape, promoting high protein expression both in vitro and in vivo . Furthermore, the PEG-PGTyr-based micelles significantly extended the half-life of the loaded mRNA after intravenous injection. Our results highlight the potential of PEG-PGTyr-based micelles as safe and effective carriers for mRNA, expediting the rational design of polymeric materials for enhanced mRNA delivery.

Polymer‐Based mRNA Delivery Strategies for Advanced Therapies

“…Thus, PEG‐PGTyr/m improved the efficacy of mRNA delivery in vivo after intramuscular injection. [ 117 ]…”

“…Thus, PEG-PGTyr/m improved the efficacy of mRNA delivery in vivo after intramuscular injection. [117] Efforts to Enhance Core Stabilization by Stimuli-Responsive Crosslinking: As noted in the previous sections, the success of mRNA therapy is critically dependent on the carriers to protect mRNA and deliver them to the cytoplasm in the desired tissues. Modifying polymeric systems with stimuli-responsive crosslinking systems that can release active mRNA in response to a desired stimulus could provide a smart strategy for enhancing mRNA stability, intracellular delivery, and specificity.…”

“…g-i) Reproduced with permission. [117] Copyright 2023, Taylor & Francis. [123] Copyright 2022, MDPI.…”

Ionizable Polymeric Micelles with Phenylalanine Moieties Enhance Intracellular Delivery of Self-Replicating RNA for Long-Lasting Protein Expression In Vivo

“…21,22 Their recent success in delivering mRNA 18,23,24 makes them attractive candidates for RepRNA delivery systems. Herein, we aim to develop PIC micelles that can load large RepRNA within its core by leveraging our recent advancements in engineering the polycation block, such as the use of flexible polycation segments 25 and side chains with π−πstacking ability, 23 for enhancing the interaction with RepRNA. Thus, we constructed low-toxicity, biodegradable block copolymers with flexible poly(ethylene glycol)−poly(glycerol) (PEG−PG) backbones conjugated with amino acids via hydrolyzable ester bonds.…”

“…Moreover, by engineering the block catiomers with moieties that ionize at endosomal pH, it is possible to formulate micelles capable of disrupting endosomal membranes to facilitate the escape of the payloads from endosomes into the cytosol. 21,22 Their recent success in delivering mRNA 18,23,24 makes them attractive candidates for RepRNA delivery systems. Herein, we aim to develop PIC micelles that can load large RepRNA within its core by leveraging our recent advancements in engineering the polycation block, such as the use of flexible polycation segments 25 and side chains with π−πstacking ability, 23 for enhancing the interaction with RepRNA.…”