Uncovering the lymphatic uptake, pharmacokinetics, and biodistribution of mRNA-lipid nanoparticles after intravenous and subcutaneous injection

Lipid nanoparticle (LNP) formulations have enabled the in vivo delivery of messenger ribonucleic acid (mRNA) vaccines and therapeutics yet the delivery of RNA remains relatively inefficient. In order to improve LNP design there is a need to better understand how current mRNA-LNP formulations are trafficked and expressed in vivo. Importantly, no prior work has quantified mRNA-LNP transport through lymphatics. In the current study we profile the thoracic lymph uptake, plasma pharmacokinetics (PK), and tissue protein expression after intravenous (IV) and subcutaneous (SC) administration in rats of three common LNP formulations (ALC-0315, SM-102 and MC3 ionizable lipids) containing muGFP-P2A-nLuc reporter mRNA. After IV administration, the SM-102 and MC3 LNP formulations provided the most effective protection of mRNA in plasma. Despite this, tissue NanoLuc® Luciferase (nLuc) expression at 32 h post-dosing was relatively similar across formulations with highest expression seen in the liver and spleen. After SC injection, all formulations supported relatively low bioavailability of mRNA (0.42-0.87% dose) and slightly higher bioavailability of ionizable and PEG lipid (<5% dose) with PK profiles of the ionizable lipid and PEG lipid not completely matching the mRNA PK profiles. There was also greater lymphatic recovery of all ionizable lipids (3.1-4.3% dose) compared to mRNA (0.62-1.4% dose) and PEG lipid (1.9-2.0% dose). Together this data suggests that mRNA is lost prior to or during lymphatic transport. Importantly, concentrations of all mRNA-LNP components were 10-1000 fold higher in thoracic lymph compared to plasma after SC injection. At 32 h after SC injection, highest nLuc expression was seen in lymph nodes and tissues near the dosing site and in the liver and spleen. These findings demonstrating that mRNA-LNPs predominantly traffic from tissue injection sites via lymphatics, mRNA-LNP components may traffic separately from each other in both lymph and blood, and tissue protein expression reflects the PK of mRNA-LNPs at early timepoints.

Abstract from PubMed (PMID 42933668). This entry was added automatically by our daily literature monitor because it matches the topics we follow; read the full paper at the original source.