Abstract Body: Introduction
Aortic aneurysm and dissection (AAD) is a life-threatening condition characterized by progressive aortic dilation, dissection, and rupture. Despite advances in surgical management for advanced disease, there are no effective pharmacological treatments to halt progression, underscoring a critical unmet need. RNA-based therapeutics delivered via lipid nanoparticles (LNPs) offer a promising strategy for targeted modulation of pathogenic molecules in cardiovascular disease. In this study, we evaluated the therapeutic potential of LNP-mediated delivery of Sting siRNA, targeting a key driver of aortic inflammation and destruction, as a novel treatment approach for AAD.
Methods
LNPs encapsulated with Cy3-scrambled siRNA and labelled with DiD (DiD-LNP/Cy3-siRNA), loaded with control siRNA (LNP/control siRNA), and Sting siRNA (LNP/Sting siRNA) were formulated using an ionizable lipid, cholesterol, a helper phospholipid, and a PEGylated lipid. The physicochemical and biological properties of LNPs were characterized. LNP/siRNA delivery to aortic wall, STING expression, and AAD incidence were evaluated in wild type mice infused with angiotensin II (Ang II) for 7 days and treated with LNP/control siRNA or LNP/Sting siRNA during Ang II infusion.
Results
The formulated LNPs exhibited optimal physicochemical properties with hydrodynamic size of 157 ± 4 nm, surface charge of -4 ± 2 mV, and polydispersity index of 0.15 ± 0.05. Encapsulation efficiency for siRNA was approximately 85%, with negligible cytotoxicity and minimal haemolytic activity. Ex vivo imaging detected DiD-LNP and Cy3-siRNA in aortic wall in Ang II-infused mice administered DiD-LNP/Cy3-siRNA, but not in saline-infused mice. Immunofluorescence analysis detected DiD-LNP and Cy3-siRNA in endothelial cells, smooth muscle cells, and macrophages in aorta wall of Ang II-infused mice. Importantly, the incidence of aortic dissection was significantly reduced (p=0.03) in Ang II-infused mice that were treated with LNPs/Sting siRNA compared to those that received LNP/control siRNA. The reduction of AAD development was associated with decreased STING protein level in aortic wall.
Conclusions
The study demonstrates the successful formulation and delivery of Sting siRNA via LNPs and establishes its efficacy in suppressing STING and preventing AAD in vivo. This study provides proof-of-concept for LNP-based RNA therapeutics in AAD; further rigorous studies are warranted to optimize the therapeutic regimen.