Amino acid supplementation enhances in vivo efficacy of lipid nanoparticle–mediated mRNA delivery in preclinical models

Lipid nanoparticles (LNPs) play a critical role in the delivery of therapeutic messenger RNA (mRNA). Despite extensive efforts to optimize lipid formulations for in vivo delivery, efficacy of mRNA by LNPs remains suboptimal in many organs. Here, we demonstrate that LNP delivery efficacy is influenced by cellular metabolism, with the physiologic metabolome imposing constraints on mRNA expression from LNPs. Using an in vitro system, we found that simulated physiologic metabolic conditions led to the down-regulation of certain amino acid metabolic programs. Supplementation with an optimized formulation of methionine, arginine, and serine as an amino acid supplement (AAS) enhanced the uptake of LNPs and the expression of delivered mRNA cargo in epithelial cells in vitro. Coadministration of AAS with LNPs led to a 5- to 20-fold improvement in mRNA expression across various cell types and lipid formulations in vitro by promoting clathrin-independent carrier-mediated endocytosis. Delivery of mRNA by LNPs coadministered with AAS by multiple routes enhanced in vivo mRNA expression in preclinical models. Delivery of mRNA encoding growth hormone by LNPs with coadministration of AAS improved the liver growth hormone expression and the therapeutic outcomes in a model of inflammatory liver damage. Delivery of gene editing materials by LNP and AAS through an intratracheal route increased lung-targeted in vivo gene editing efficiency compared with LNP alone. The addition of an optimized AAS as a codelivered agent with LNPs may provide a simple strategy to broadly improve the efficacy of mRNA-based cell and gene therapies.