Self‐Degradable Lipid‐Like Materials Based on “Hydrolysis accelerated by the intra‐Particle Enrichment of Reactant (HyPER)” for Messenger RNA Delivery

Abstract

RNA-based therapeutics is a promising approach for curing intractable diseases by manipulating various cellular functions. For eliciting RNA (i.e., mRNA and siRNA) functions successfully, the RNA in the extracellular space must be protected and it must be delivered to the cytoplasm. In this study, the development of a self-degradable lipid-like material that functions to accelerate the collapse of lipid nanoparticles (LNPs) and the release of RNA into cytoplasm is reported. The self-degradability is based on a unique reaction "Hydrolysis accelerated by intra-Particle Enrichment of Reactant (HyPER)." In this reaction, a disulfide bond and a phenyl ester are essential structural components: concentrated hydrophobic thiols that are produced by the cleavage of the disulfide bonds in the LNPs drive an intraparticle nucleophilic attack to the phenyl ester linker, which results in further degradation. An oleic acid-scaffold lipid-like material that mounts all of these units (ssPalmO-Phe) shows superior transfection efficiency to nondegradable or conventional materials. The insertion of the aromatic ring is unexpectedly revealed to contribute to the enhancement of endosomal escape. Since the intracellular trafficking is a sequential process that includes cellular uptake, endosomal escape, the release of mRNA, and translation, the improvement in each process synergistically enhances the gene expression.

Self-assembled mRNA vaccines

“…Examples of ILs containing bio-reducible disulfide linkage includes BAMEA-O16B [ 197 ] and ssPalmO-Phe lipid ( Fig. 6 D) [ 198 ].

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“…Studying the early stages of self-assembly requires an extremely fresh sample and a technique capable of nanoscale acquisition both in spatial and temporal dimensions. For this reason, computational approaches are becoming increasingly more popular for understanding the early structural developments of self-assembly, which may provide insights into the cellular uptake and payload release [ 165 , 277 ]. Latest advances in molecular dynamics simulations of biomolecule self-assembly are highlighted in a recent perspective [ 278 ].…”

Understanding In Vivo Fate of Nucleic Acid and Gene Medicines for the Rational Design of Drugs

“…We have already stated earlier that non-viral vectors that are taken up by endocytosis need to escape from the endosomes. For this escape, pH-sensitive substances based on endosomal acidification are commonly used [ 25 , 79 , 151 , 152 , 153 , 154 ]. For naked oligonucleotide drugs, it is still not fully understood how they escape from endosomes.…”

“…This strategy using electrolytes for complex formation has been applied to bubble lipopolyplexes, which are composed of anionic liposomes, protamine, plasmid DNA, and echo gas C 3 F 8 , and has shown to improve gas entrapment efficiency [ 210 ]. In addition, a moderate concentration of sodium chloride is added to LNP [ 154 ]. During plasmid DNA purification, alcohol precipitation is usually performed, but depending on the method, salts are likely to be contaminated.…”

“…In the LCP, a cyclic CR8C peptide having a disulfide bond was used [ 38 ]. Other lipid-like molecules, called ssPalm, are designed to have no charge at physiological pH and become positively charged upon endosomal acidification, thus promoting endosomal escape and cleavage of disulfide bonds in the cytoplasm to dissociate the encapsulated nucleic acids [ 79 , 99 , 154 , 284 ].…”