Silencing of the von Willebrand factor gene in proatherothrombotic APOE*3-Leiden.CETP transgenic mice

Background: Elevated von Willebrand factor (VWF) levels correlate with higher risk of atherosclerosis-related arterial thrombosis (atherothrombosis). Silencing the VWF gene via small-interfering RNAs (siRNAs) could mitigate this risk. Previous studies successfully delivered siRNA to the endothelium of healthy, wild-type (WT) mice using lipid nanoparticles (LNPs). Objectives: This study aimed to investigate whether the LNP-siRNA strategy could achieve endothelium-specific Vwf-silencing under diseased conditions of prolonged hypercholesterolemia and atherothrombosis-prone vasculature. Methods: Female transgenic mice expressing a variant of human APOE*3 (ie, APOE*3 Leiden) and human cholesteryl ester transfer protein (CETP), fed a cholesterol-enriched diet for 18 weeks, received an intravenous injection of LNP-encapsulated siRNA targeting Vwf (siVwf) or scrambled control siRNA at 1.5 mg siRNA/kg. For comparison, the same LNP-siRNAs were administered to young, chow-fed WT mice. Plasma VWF and Vwf mRNA levels were measured 96 hours after injection, with immunofluorescence analysis of lungs and heart aortic root to assess VWF protein expression. Results: APOE*3 Leiden.CETP mice exhibited elevated plasma VWF levels compared with WT mice, alongside hypercholesterolemia and aortic atherosclerosis. siVwf administration led to over 85% reduction in plasma VWF in both strains, with a strong reduction in lung Vwf mRNA and VWF protein in the pulmonary endothelium. Similarly, siVwf treatment resulted in the virtual absence of VWF protein in the endothelial lining of the aortic root of both nondiseased (WT mice) and atherosclerotic (APOE*3 Leiden.CETP mice) vessel walls. Conclusion: The LNP-siRNA targeting Vwf strongly reduced plasma and endothelial VWF in mice with hypercholesterolemia and advanced atherosclerosis, indicating feasibility to target endothelial VWF under proatherothrombotic conditions.