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Lipid shape and packing are key for optimal design of pH-sensitive mRNA lipid nanoparticles

Tesei, Giulio LU ; Hsiao, Ya Wen ; Dabkowska, Aleksandra ; Grõnberg, Gunnar ; Arteta, Marianna Yanez ; Ulkoski, David ; Bray, David J. ; Trulsson, Martin LU orcid ; Ulander, Johan and Lund, Mikael LU orcid , et al. (2024) In Proceedings of the National Academy of Sciences of the United States of America 121(2).
Abstract

The ionizable-lipid component of RNA-containing nanoparticles controls the pH-dependent behavior necessary for an efficient delivery of the cargo - the so-called endosomal escape. However, it is still an empirical exercise to identify optimally performing lipids. Here, we study two well-known ionizable lipids, DLin-MC3-DMA and DLin-DMA using a combination of experiments, multiscale computer simulations, and electrostatic theory. All-atom molecular dynamics simulations, and experimentally measured polar headgroup pKavalues, are used to develop a coarse-grained representation of the lipids, which enables the investigation of the pH-dependent behavior of lipid nanoparticles (LNPs) through Monte Carlo simulations, in the absence... (More)

The ionizable-lipid component of RNA-containing nanoparticles controls the pH-dependent behavior necessary for an efficient delivery of the cargo - the so-called endosomal escape. However, it is still an empirical exercise to identify optimally performing lipids. Here, we study two well-known ionizable lipids, DLin-MC3-DMA and DLin-DMA using a combination of experiments, multiscale computer simulations, and electrostatic theory. All-atom molecular dynamics simulations, and experimentally measured polar headgroup pKavalues, are used to develop a coarse-grained representation of the lipids, which enables the investigation of the pH-dependent behavior of lipid nanoparticles (LNPs) through Monte Carlo simulations, in the absence and presence of RNA molecules. Our results show that the charge state of the lipids is determined by the interplay between lipid shape and headgroup chemistry, providing an explanation for the similar pH-dependent ionization state observed for lipids with headgroup pKa values about one-pH-unit apart. The pH dependence of lipid ionization is significantly influenced by the presence of RNA, whereby charge neutrality is achieved by imparting a finite and constant charge per lipid at intermediate pH values. The simulation results are experimentally supported by measurements of α-carbon 13C-NMR chemical shifts for eGFP mRNA LNPs of both DLin-MC3-DMA and DLin-DMA at various pH conditions. Further, we evaluate the applicability of a mean-field Poisson-Boltzmann theory to capture these phenomena.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
lipid ionization, lipid nanoparticle, pH controlled release, RNA encapsulation
in
Proceedings of the National Academy of Sciences of the United States of America
volume
121
issue
2
article number
e2311700120
publisher
National Academy of Sciences
external identifiers
  • pmid:38175863
  • scopus:85181851377
ISSN
0027-8424
DOI
10.1073/pnas.2311700120
language
English
LU publication?
yes
id
a90c0d33-dff4-4b18-9291-5a8fb34fb6ec
date added to LUP
2024-02-08 16:14:00
date last changed
2025-05-24 16:20:38
@article{a90c0d33-dff4-4b18-9291-5a8fb34fb6ec,
  abstract     = {{<p>The ionizable-lipid component of RNA-containing nanoparticles controls the pH-dependent behavior necessary for an efficient delivery of the cargo - the so-called endosomal escape. However, it is still an empirical exercise to identify optimally performing lipids. Here, we study two well-known ionizable lipids, DLin-MC3-DMA and DLin-DMA using a combination of experiments, multiscale computer simulations, and electrostatic theory. All-atom molecular dynamics simulations, and experimentally measured polar headgroup pK<sub>a</sub>values, are used to develop a coarse-grained representation of the lipids, which enables the investigation of the pH-dependent behavior of lipid nanoparticles (LNPs) through Monte Carlo simulations, in the absence and presence of RNA molecules. Our results show that the charge state of the lipids is determined by the interplay between lipid shape and headgroup chemistry, providing an explanation for the similar pH-dependent ionization state observed for lipids with headgroup pKa values about one-pH-unit apart. The pH dependence of lipid ionization is significantly influenced by the presence of RNA, whereby charge neutrality is achieved by imparting a finite and constant charge per lipid at intermediate pH values. The simulation results are experimentally supported by measurements of α-carbon <sup>13</sup>C-NMR chemical shifts for eGFP mRNA LNPs of both DLin-MC3-DMA and DLin-DMA at various pH conditions. Further, we evaluate the applicability of a mean-field Poisson-Boltzmann theory to capture these phenomena.</p>}},
  author       = {{Tesei, Giulio and Hsiao, Ya Wen and Dabkowska, Aleksandra and Grõnberg, Gunnar and Arteta, Marianna Yanez and Ulkoski, David and Bray, David J. and Trulsson, Martin and Ulander, Johan and Lund, Mikael and Lindfors, Lennart}},
  issn         = {{0027-8424}},
  keywords     = {{lipid ionization; lipid nanoparticle; pH controlled release; RNA encapsulation}},
  language     = {{eng}},
  number       = {{2}},
  publisher    = {{National Academy of Sciences}},
  series       = {{Proceedings of the National Academy of Sciences of the United States of America}},
  title        = {{Lipid shape and packing are key for optimal design of pH-sensitive mRNA lipid nanoparticles}},
  url          = {{http://dx.doi.org/10.1073/pnas.2311700120}},
  doi          = {{10.1073/pnas.2311700120}},
  volume       = {{121}},
  year         = {{2024}},
}