Safer non-viral DNA delivery using lipid nanoparticles loaded with endogenous anti-inflammatory lipids

The value of lipid nanoparticles (LNPs) for delivery of messenger RNA (mRNA) was demonstrated by the coronavirus disease 2019 (COVID-19) mRNA vaccines, but the ability to use LNPs to deliver plasmid DNA (pDNA) would provide additional advantages, such as longer-term expression and availability of promoter sequences. However, pDNA-LNPs face substantial challenges, such as toxicity and low delivery efficiency. Here we show that pDNA-LNPs induce acute inflammation in naive mice that is primarily driven by the cGAS–STING pathway. Inspired by DNA viruses that inhibit this pathway for replication, we loaded endogenous lipids that inhibit STING into pDNA-LNPs. Loading nitro-oleic acid (NOA) into pDNA-LNPs (NOA-pDNA-LNPs) ameliorated serious inflammatory responses in vivo, enabling safer, prolonged transgene expression—11.5 times greater than that of mRNA-LNPs at day 32. Additionally, we performed a small LNP formulation screen to iteratively optimize transgene expression and increase expression 50-fold in vitro. pDNA-LNPs loaded with NOA and other bioactive molecules should advance genetic medicine by enabling longer-term and promoter-controlled transgene expression. Lipid nanoparticles carrying plasmid DNA and an inflammation inhibitor enable longer transgene expression than mRNA nanoparticles.