Ohio State University Columbus, Ohio, United States
Purpose: mRNA based vaccines have ascended rapidly in recently years due to the FDA approval or Emergency Use Authorization for the two-mRNA based COVID-19 vaccines. As evidenced by these rapid development and dissemination, mRNA-based vaccines embody many advantageous features such as safety, efficacy, versatility, but most importantly, speed of mass production. However, mRNAs are rapidly degraded once administered and require delivery systems, often in the form of lipid nanoparticles, to safeguard from degradation and increase cellular uptake and consequently, the release of the mRNA into the cytoplasm for translation. Therefore, the successes of mRNA-based vaccines can be elevated by designing a rational lipid nanoparticles system to facilitate the safe and efficacious delivery of mRNAs in vivo. We have synthesized novel ionizable lipid derivatives, which were then screened and optimized in formulations through orthogonal array analysis to increase the delivery efficiency of encapsulated mRNA. Methods: A library of novel ionizable lipids were first screened in JAWSII cell line, an immortalized mouse Dendritic Cell line. Top performing candidate was then selected, and the formulation component was evaluated and optimized through an orthogonal array analysis utilizing a high-throughput luciferase assay to assess for mRNA delivery efficiency in both JAWSII and C2C12 cell line, an immortalized mouse myoblast cell line. The formulated lipid nanoparticles (LNPs) were additionally characterized for various physicochemical properties including size, zeta-potential, mRNA encapsulation efficiency, and cell cytotoxicity. Results: The top novel ionizable lipid compound was optimized in overall LNPs formulation, which resulted in a threefold increase in delivery efficiency after optimization through orthogonal array analysis. The resulting top LNPs exhibited ideal physicochemical properties such as small hydrodynamic size of less than 150 nm in diameter, low polydisperity index, and a slight positive zeta potential. More importantly, the top LNPs formulation demonstrated high mRNA delivery efficiency, which was more than 10-fold higher than LNPs formulations based on FDA approved LNPs formulations. Conclusion: The identified novel ionizable lipid nanoparticles formulation has the potential to be applied for various vaccine applications for infectious diseases or cancers. The optimized LNPs will be evaluated in more sophisticated in vivo systems to fully analyze its potential to serve as a highly valuable LNPs system to delivery mRNA, especially in context as vaccines.
