Nat Commun. 2025 May 20;16(1):4700. doi: 10.1038/s41467-025-60040-9.

Freezing induced incorporation of betaine in lipid nanoparticles enhances mRNA delivery

Abstract
Lipid nanoparticles (LNPs) are key non-viral carriers for mRNA vaccines and therapeutics, but the inherent instability of mRNA necessitates sub-zero storage with cryoprotectants (CPAs) to prevent freeze-induced LNP aggregation and compromised mRNA delivery. Here we show that ice formation during freezing concentrates CPAs with LNPs in the remaining liquid-a phenomenon known as freeze concentration. This creates a steep concentration gradient of CPAs across the lipid membrane that drives passive CPAs diffusion into LNPs. By leveraging this process, we developed betaine-based CPAs that both preserve the stability of LNP and enter LNP during freeze-thaw. The incorporated betaine enhances endosomal escape and boosts mRNA delivery of LNP. In female mice, betaine-loaded LNPs elicit stronger humoral and cellular immune responses, providing dose-sparing advantages. These findings highlight freeze concentration as a promising LNP formulation strategy and underscore the role of CPA as active modulators of LNP structure and function.

Product: lipids for LNP