PBAE-PEG-based lipid nanoparticles for lung cell-specific gene delivery

Exemplified by successful use in COVID-19 vaccination, delivery of modified mRNA encapsulated in lipid nanoparticles (LNPs) provides a framework for treating various genetic and acquired disorders. However, LNPs that can deliver mRNA into specific lung cell types have not yet been established. Here, we sought to determine whether poly(β-amino ester)s (PBAE) or PEGylated PBAE (PBAE-PEG) in combination with 4A3-SC8/DOPE/cholesterol/DOTAP LNPs could deliver mRNA into different types of lung cells in vivo. PBAE-PEG/LNP was similar to Lipofectamine MessengerMAX followed by PBAE/LNP for mRNA transfection efficiency in HEK293T cells in vitro. PBAE-PEG/LNP administered by intravenous (IV) injection achieved 73% mRNA transfection efficiency into lung endothelial cells, while PBAE-PEG/LNP administered by intratracheal (IT) injection achieved 55% efficiency in lung alveolar type II (ATII) epithelial cells in mice in vivo. PBAE/LNP administered by IT injection were superior for specific delivery into lung airway club epithelial cells compared to PBAE-PEG/LNP. Lipofectamine MessengerMAX was inactive in vivo. 5-Methoxyuridine-modified mRNA was more efficient than unmodified mRNA in vivo but not in vitro. Our findings indicate that PBAE-PEG/LNP and PBAE/LNP can transfect multiple lung cell types in vivo, which can be applied in gene therapy targeting genetic lung diseases.