Ultrasound-Enhanced Spleen-Targeted mRNA Delivery via Fluorinated PEGylated Lipid Nanoparticles for Immunotherapy

Lipid nanoparticles (LNPs) based messenger RNA (mRNA) therapeutics hold immense promise for treating a wide array of diseases, while their nonhepatic organs targeting and insufficient endosomal escape efficiency remain challenges. For LNPs, polyethylene glycol (PEG) lipids have a crucial role in stabilizing them in aqueous medium, but they severely hinder cellular uptake and reduce transfection efficiency. In this study, we designed ultrasound (US)-assisted fluorinated PEGylated LNPs (F-LNPs) to enhance spleen-targeted mRNA delivery and transfection. Through liquid-to-gas phase transition, we enabled the controlled shedding of fluorinated PEG lipids from F-LNPs, facilitating cellular uptake, membrane fusion, and mRNA release. In vivo results demonstrated that US-assisted F-LNPs increased mRNA transfection approximately 4.0-fold in the spleen following intravenous administration. Notably, the F-LNPs achieved effective mRNA delivery to antigen-presenting cell subsets, such as dendritic cells, macrophages, and B cells. The targeted delivery of full-length ovalbumin-encoding mRNA vaccine induced significant CD8⁺ T cell response and exhibited excellent therapeutic effect against the ovalbumin-transduced B16F10 tumor model. These findings establish a novel strategy for spleen-specific mRNA delivery through the combination of fluorinated PEG lipids and US treatment, which holds substantial promise for enhancing the efficacy of immunotherapy, potentially broadening the scope of clinical applications for mRNA-based therapy.