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Published on: February 1, 2019
Polymeric Micelles with pH-Responsive Cross-Linked Core Enhance In Vivo mRNA Delivery
Wenqian Yang1, Pengwen Chen1, Eger Boonstra1
1Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Abstract:
Messenger RNA (mRNA) is emerging as a promising therapeutic modality for a variety of diseases. Because of the fragility and limited intracellular access of mRNA, the development of delivery technologies is essential for promoting the applicability of mRNA-based treatments. Among effective nanocarriers, polymeric micelles loading mRNA by polyion complex (PIC) formation with block catiomers have the potential to meet the delivery needs. Since PICs are relatively unstable in in vivo settings, herein, we constructed mRNA-loaded micelles having pH-responsive cross-linked cores by complexing mRNA with cis-aconitic anhydride-modified poly(ethylene glycol)-poly(l-lysine) (PEG-pLL(CAA)) block copolymers. The micelles were stable at physiological pH (pH 7.4) but achieved the complete release of the mRNA at endosomal pH (pH 5.5-4.5). The cross-linking also enhanced the stability of the micelles against disassembly from polyanions and protected the loaded mRNA from degradation by nucleases. Thus, the cross-linked micelles increased the delivery of mRNA to cancer cells, promoting protein expression both in vitro and in vivo. Our results highlight the potential of PEG-pLL(CAA)-based micelles for mRNA delivery.
Insights
New cross-linked polymeric micelles effectively deliver messenger RNA (mRNA) therapeutics. These pH-responsive nanocarriers protect fragile mRNA, enhance cellular uptake, and improve protein expression in vitro and in vivo.
Area of Science:
- Biotechnology
- Nanomedicine
- Polymer Chemistry
Background:
- Messenger RNA (mRNA) therapeutics show great promise but require effective delivery systems due to mRNA fragility and limited cellular access.
- Polymeric micelles using polyion complex (PIC) formation with block catiomers are potential nanocarriers for mRNA.
- Existing PIC-based systems face stability challenges in vivo.
Purpose of the Study:
- To develop a novel, pH-responsive, cross-linked micelle system for enhanced mRNA delivery.
- To improve the stability and intracellular release of mRNA using a novel block copolymer.
- To evaluate the efficacy of these micelles for mRNA delivery and protein expression in vitro and in vivo.
Main Methods:
- Synthesized pH-responsive block copolymers (PEG-pLL(CAA)) by modifying poly(ethylene glycol)-poly(l-lysine) with cis-aconitic anhydride.
- Formed mRNA-loaded micelles with pH-responsive cross-linked cores via polyion complexation.
- Assessed micelle stability at physiological and endosomal pH, nuclease resistance, and mRNA release kinetics.
- Evaluated mRNA delivery, protein expression, and therapeutic efficacy in cancer cells in vitro and in vivo.
Main Results:
- Constructed stable, pH-responsive cross-linked micelles capable of encapsulating mRNA.
- Micelles demonstrated stability at pH 7.4 and efficient mRNA release at endosomal pH (5.5-4.5).
- Cross-linking enhanced micelle stability against polyanions and protected mRNA from nuclease degradation.
- Achieved improved mRNA delivery to cancer cells, leading to enhanced protein expression both in vitro and in vivo.
Conclusions:
- pH-responsive cross-linked micelles based on PEG-pLL(CAA) are effective nanocarriers for mRNA delivery.
- This system overcomes the limitations of traditional PICs, offering enhanced stability and controlled release.
- The developed micelles hold significant potential for advancing mRNA-based therapeutics for various diseases, including cancer.
