Activatable membrane-destabilizing lipid-polycations for direct cytosolic delivery of mRNA and liver fibrosis therapy

Cytosolic delivery is the fundamental prerequisite for messenger RNA (mRNA) therapeutics. However, most delivery systems rely on endocytosis and are limited by inefficient endosomal escape, suffering from low delivery efficiency and strong dose dependence. Here, we report a ctivatable m embrane- d estabilizing lipid- p olycations (AMDPs) that enable a predominantly non-endocytic mRNA delivery via cell-membrane anchoring and destabilization. AMDPs are constructed by introducing esterase-labile quaternary ammonium side chains with hydrophobic motifs onto a poly(L-lysine) backbone, allowing stable mRNA complexation through electrostatic and hydrophobic interactions. Upon enzymatic activation, AMDPs undergo a cascade-triggered cleavage process, in which the hydrophobic moieties are removed to expose carboxylates adjacent to cationic alkyl chains. This transformation generates an inverse phospholipid-like zwitterionic architecture that promotes membrane pairing and localized destabilization, enabling direct cytosolic release of mRNA. AMDPs realizes dose-independent transfection, with 6.25 ng mRNA producing protein expression comparable to 200 ng, corresponding to a 32-fold reduction in mRNA input. Following intravenous administration, AMDPs achieve liver-selective mRNA expression, with 95% of total protein expression confined to the liver. Therapeutic delivery of interleukin-10 and relaxin mRNAs significantly attenuates fibrosis and restores liver architecture in a CCl 4 -induced mouse model. This work establishes a mechanistically distinct and non-endocytic strategy for low-dose and organ-targeted mRNA therapy. Download: Download high-res image (164KB) Download: Download full-size image