Fig. 1: Schematic illustration of fibrosis overexpression and retention (FORT) strategy for metabolic dysfunction-associated steatohepatitis (MASH) treatment.

Collagen binding domain (CBD) screened from the endogenous proteins was added to the C terminus of RLN with connection of Glycine-Serine linker (GS) and coded by mRNA. The therapeutic recombinant mRNAs were encapsulated with a fibrosis-targeted LNP and intravenously (i.v.) administrated for enhanced mRNA expression and fibrotic liver retention. To achieve enhanced mRNA expression, we fabricated a five component LNPs by substituting 25 mol% of cholesterol in ALC-0315 LNPs with a carboxylic retinoid, all-trans retinoic acid (ATRA), which shows over a ~ 10-fold increase in mRNA expression compared to traditional ALC-0315 LNPs in fibrotic and MASH models. Mechanistically, the carboxylic retinoid rearranges on LNPs surfaces during encapsulating mRNA, improving both endocytosis and endosomal release. The added CBD to the therapeutic proteins further extended liver retention. Thereby, the FORT strategy allows the fusion protein to be expressed and anchored in situ, creating a depot that enhances the anti-fibrotic response. GS Glycine-Serine linker, HSC hepatic stellate cell, RBC red blood cell, STRA6 stimulated by retinoic acid 6 (a surface receptor for transported retinoids). Figure 1 was created with BioRender.com released under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0).