Buffer optimization of siRNA-lipid nanoparticles mitigates lipid oxidation and RNA-lipid adduct formation
Daniel A. Estabrook, Lihua Huang, Olivia R. Lucchese, Dylan J. Charland, Yu Zhao, Fareed Bhasha Sayyed, Jonas Y. Buser, Younghoon Oh, Xingyan Liu, Harmon A. Johnson, Kenneth R. Rodriguez, Noah A. Wambolt, Sonia A. Corba, Geoffrey T. Nash, Dennis Yang, Tingting Wang
Abstract
Lipid nanoparticles are a versatile class of clinically approved drug delivery vehicles, particularly for nucleic acid cargoes. Despite this, these materials often suffer from instability issues that limit shelf-life or necessitate storage at ultra-cold temperatures. Herein, we demonstrate that the oxidation of unsaturated hydrocarbons within ionizable lipid tails results in the production of a dienone species that changes the conformation of the lipid tail and generates an electrophilic degradant that reacts with neighboring siRNA cargoes to produce siRNA-lipid adducts. This mechanism highlights the interplay between lipid degradation, colloidal instability, RNA-lipid adduct formation, and loss of bioactivity. In this work, we show that revised drug product matrixes, including mildly acidic, histidine-containing formulations, can improve room temperature stability of siRNA-lipid nanoparticles by mitigating these oxidative degradation mechanisms.