PEG-Lipid Interfacial Architecture Enables Zn2+-Dependent Redistribution of LNP-Mediated mRNA Expression Toward the Spleen.

Abstract

PEG-lipid interfaces influence LNP nano-bio interactions, yet conventional PEG-lipid formulations differ simultaneously in several molecular features that complicate attribution of ion-dependent effects. Here, using structurally defined DMA-PEG16-OMe as a discrete PEG-lipid model and conventional DMA-PEG2k-OMe as a comparator, we show that Zn2+ addition produces a concentration-dependent redistribution of organ-associated LNP-mediated mRNA expression from the liver toward the spleen. This redistribution was most pronounced in the PEG16 formulation and was not observed to the same extent in the conventional PEG2k formulation, supporting PEG-lipid interfacial architecture as an important determinant of the Zn2+-dependent response. Mechanistically, Zn2+ is associated with protein-corona remodeling, including enrichment of apolipoprotein H (ApoH; β2-glycoprotein I), a corona component previously linked to splenic tropism, together with reduced inflammatory transcriptional activation. In a prophylactic B16F10-OVA-luc challenge model, Zn@PEG16-LNP treatment was associated with improved tumor control, higher total serum IgG and IgG1 signals, and stronger SIINFEKL-responsive CD8+ T-cell responses. Together, these findings identify PEG-lipid interfacial architecture and Zn2+ incorporation as a simple formulation strategy for spleen-directed mRNA delivery.