Keywords
Lipid nanoparticles, mRNA, mRNA delivery
Authors
Masoomeh Khalifeh, Rik Oude Egberink, Rona Roverts, Roland Brock
Abstract
Messenger RNA is a highly promising biotherapeutic modality with great potential in preventive and therapeutic
vaccination, and in the modulation of cellular function through transient expression of therapeutic proteins.
However, for cellular delivery, mRNA requires packaging into delivery vehicles that mediate uptake and also
shield the mRNA against degradation. Lipid-coated calcium phosphate (LCP) nanoparticles encapsulate the
mRNA in a calcium phosphate core, which is coated by a bilayer of structural lipids, positively charged lipids and
pegylated lipid to mediate cellular uptake and achieve colloidal stabilization. Here, we show that such nanoparticles
using positively charged lipids achieve cellular uptake but only poor cytosolic mRNA delivery. However,
mRNA release could be greatly enhanced through incorporation of ionizable lipids into the outer leaflet of
the lipid bilayer. We optimized the composition and molar ratios of ionizable lipids, positive lipid, cholesterol,
and polyethylene glycol (PEG) and evaluated the potency of the formulations for the cellular delivery of mRNA.
Whereas in lipid nanoparticles, the ionizable lipid has a main role in the complexation of the mRNA, our study
provides a new paradigm for the employment of ionizable cationic lipids in nanocarriers other than lipid
nanoparticles (LNPs) to boost the endosomal release of nucleic acids.