New phospholipids improve functional mRNA delivery via lipid nanoparticles

Researchers develop innovative phospholipids that improve the functional delivery of mRNA via lipid nanoparticles, paving the way for advanced therapeutic applications.

A groundbreaking study conducted by researchers at Hokkaido University has unveiled a novel class of zwitterionic phospholipids capable of significantly enhancing the functional delivery of mRNA. The study was published in the Advanced Science.

A new phospholipid, DOPE-Cx, was derived from a compound called DOPE, which is itself a phospholipid. Phospholipids are key components of cell membranes, and are used in the creation of lipid nanoparticles (LNPs) for targeted drug delivery. DOPE-Cx can form a special structure called a "cubic phase," which helps overcome a major challenge in mRNA delivery by LNPs: endosomal escape. LNPs are taken into the cell in the form of endosomes, and escape from these endosomes (endosomal escape) is a key hurdle that limits the effectiveness of mRNA therapies.

The research, led by Associate Professor Yusuke Sato at the Faculty of Pharmaceutical Sciences, Hokkaido University, demonstrates that DOPE-Cx lipids with specific hydrophobic chain structures induce non-lamellar cubic phases when mixed with phosphatidylcholine (PC). This unique property facilitates membrane fusion-mediated endosomal escape, leading to improved mRNA expression in the liver compared to conventional phospholipids like DSPC and DOPE.

Endosomal escape remains one of the most significant challenges in RNA delivery, with efficiencies often below 10%. Our study highlights the potential of rationally engineered phospholipids like DOPE-Cx to overcome this limitation and enhance the therapeutic applications of mRNA."

Yusuke Sato, Associate Professor, Faculty of Pharmaceutical Sciences, Hokkaido University

Specific DOPE-Cx derivatives, such as DOPE-C8, demonstrated significantly higher mRNA expression levels in the liver. These lipids were rapidly eliminated from liver tissue, reducing long-term accumulation and toxicity concerns. Engineered functionalized phospholipids hold great promise for developing lipid nanoparticles (LNPs) used in mRNA vaccines, cancer treatment, protein replacement therapy, and more.

The derivative DOPE-C8, in particular, demonstrated the highest efficiency, enhancing endosomal escape and protecting mRNA from degradation in the bloodstream. It was also rapidly cleared from the liver, minimizing toxicity risks. However, these findings are limited to mice, and further research is needed to confirm their applicability in humans or other animals.

"This research not only advances our understanding of lipid-based delivery systems but also opens new avenues for the rational design of functionalized phospholipids," adds Professor Hideyoshi Harashima, co-author of the study. 

While the current study focuses on liver-specific mRNA delivery, the team plans to explore the broader applicability of DOPE-Cx lipids across different tissues and administration routes. Further investigations into the detailed mechanisms of membrane fusion and spatiotemporal interactions will guide the development of next-generation LNPs.