Back to Search Start Over

pH-dependent structural transitions in cationic ionizable lipid mesophases are critical for lipid nanoparticle function.

pH-dependent structural transitions in cationic ionizable lipid mesophases are critical for lipid nanoparticle function.

Authors :
Philipp, Julian
Dabkowska, Aleksandra
Reiser, Anita
Frank, Kilian
Krzysztoń, Rafał
Brummer, Christiane
Nickel, Bert
Blanchet, Clement E.
Sudarsan, Akhil
Ibrahim, Mohd
Johansson, Svante
Skantze, Pia
Skantze, Urban
Östman, Sofia
Johansson, Marie
Henderson, Neil
Elvevold, Kjetil
Smedsrød, Bård
Schwierz, Nadine
Lindfors, Lennart
Source :
Proceedings of the National Academy of Sciences of the United States of America. 12/12/2023, Vol. 120 Issue 50, p1-12. 22p.
Publication Year :
2023

Abstract

Lipid nanoparticles (LNPs) are advanced core-shell particles for messenger RNA (mRNA) based therapies that are made of polyethylene glycol (PEG) lipid, distearoylphosphatidylcholine (DSPC), cationic ionizable lipid (CIL), cholesterol (chol), and mRNA. Yet the mechanism of pH-dependent response that is believed to cause endosomal release of LNPs is not well understood. Here, we show that eGFP (enhanced green fluorescent protein) protein expression in the mouse liver mediated by the ionizable lipids DLin-MC3-DMA (MC3), DLin-KC2-DMA (KC2), and DLinDMA (DD) ranks MC3 = KC2 > DD despite similar delivery of mRNA per cell in all cell fractions isolated. We hypothesize that the three CIL-LNPs react differently to pH changes and hence study the structure of CIL/chol bulk phases in water. Using synchrotron X-ray scattering a sequence of ordered CIL/chol mesophases with lowering pH values are observed. These phases show isotropic inverse micellar, cubic Fd3m inverse micellar, inverse hexagonal HII and bicontinuous cubic Pn3m symmetry. If polyadenylic acid, as mRNA surrogate, is added to CIL/chol, excess lipid coexists with a condensed nucleic acid lipid Hc II phase. The next-neighbor distance in the excess phase shows a discontinuity at the Fd3m inverse micellar to inverse hexagonal HII transition occurring at pH 6 with distinctly larger spacing and hydration for DD vs. MC3 and KC2. In mRNA LNPs, DD showed larger internal spacing, as well as retarded onset and reduced level of DD-LNP-mediated eGFP expression in vitro compared to MC3 and KC2. Our data suggest that the pH-driven Fd3m-H II transition in bulk phases is a hallmark of CIL-specific differences in mRNA LNP efficacy. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00278424
Volume :
120
Issue :
50
Database :
Academic Search Index
Journal :
Proceedings of the National Academy of Sciences of the United States of America
Publication Type :
Academic Journal
Accession number :
174291592
Full Text :
https://doi.org/10.1073/pnas.2310491120