|Title||Ionization and structural properties of mRNA lipid nanoparticles influence expression in intramuscular and intravascular administration.|
|Publication Type||Journal Article|
|Year of Publication||2021|
|Authors||Carrasco, MJ, Alishetty, S, Alameh, M-G, Said, H, Wright, L, Paige, M, Soliman, O, Weissman, D, Cleveland, TE, Grishaev, A, Buschmann, MD|
|Date Published||2021 08 11|
|Keywords||Administration, Intravenous, Animals, Drug Compounding, Gene Expression, Humans, Hydrogen-Ion Concentration, Injections, Intramuscular, Ions, Lipids, Mice, Molecular Structure, Nanoparticles, RNA, Messenger, Spectrum Analysis, Tissue Distribution, Transfection|
Lipid Nanoparticles (LNPs) are used to deliver siRNA and COVID-19 mRNA vaccines. The main factor known to determine their delivery efficiency is the pKa of the LNP containing an ionizable lipid. Herein, we report a method that can predict the LNP pKa from the structure of the ionizable lipid. We used theoretical, NMR, fluorescent-dye binding, and electrophoretic mobility methods to comprehensively measure protonation of both the ionizable lipid and the formulated LNP. The pKa of the ionizable lipid was 2-3 units higher than the pKa of the LNP primarily due to proton solvation energy differences between the LNP and aqueous medium. We exploited these results to explain a wide range of delivery efficiencies in vitro and in vivo for intramuscular (IM) and intravascular (IV) administration of different ionizable lipids at escalating ionizable lipid-to-mRNA ratios in the LNP. In addition, we determined that more negatively charged LNPs exhibit higher off-target systemic expression of mRNA in the liver following IM administration. This undesirable systemic off-target expression of mRNA-LNP vaccines could be minimized through appropriate design of the ionizable lipid and LNP.
|Alternate Journal||Commun Biol|