A Lung-Expressing mRNA Delivery Platform with Tunable Activity in Hypoxic Environments.

Messenger RNA (mRNA) delivery platforms often facilitate protein expression in the liver following intravenous injection and have been optimized for use in normally oxygenated cells (21% O 2 atmosphere). However, there is a growing need for mRNA therapy in diseases affecting non-liver organs, such as the lungs. Additionally, many diseases are characterized by hypoxia (<21% O 2 atmosphere), a state of abnormally low oxygenation in cells and tissues that can reduce the efficacy of mRNA therapies by upwards of 80%. Here, we report a Tu nable L ung- E xpressing Nanoparticle P latform ( TULEP ) for mRNA delivery, whose properties can be readily tuned for optimal expression in hypoxic environments. Briefly, our study begins with the synthesis and characterization of a novel amino acrylate polymer that can be effectively complexed with mRNA payloads into TULEP s. We study the efficacy and mechanism of mRNA delivery using TULEP , including analysis of the cellular association, endocytosis mechanisms, endosomal escape, and protein expression in a lung cell line. We then evaluate TULEP under hypoxic conditions and address hypoxia-related deficits in efficacy by making our system tunable with adenosine triphosphate (ATP). Finally, we conclude our study with an in vivo analysis of mRNA expression, biodistribution, and tolerability of the TULEP platform in mice. In presenting these data, we hope that our work highlights the utility of TULEP s for tunable and effective mRNA delivery while more broadly highlighting the utility of considering oxygen levels when developing mRNA delivery platforms.