CRISPR-Cas9-Mediated Knockout of PCSK9 Reduces Atherogenesis in Murine Models

Background: Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a central role in cholesterol homeostasis by promoting degradation of hepatic low-density lipoprotein receptors (LDLR), thereby elevating circulating LDL-cholesterol (LDL-C) levels and contributing to atherogenesis. While monoclonal antibodies targeting PCSK9 have proven effective in lowering LDL-C, they require lifelong administration. CRISPR-Cas9 gene editing offers a potential one-time therapeutic strategy by permanently disrupting PCSK9 expression and achieving durable lipid-lowering effects. Methods and Results: This study investigated the impact of CRISPR-Cas9–mediated PCSK9 knockout on lipid metabolism and atherosclerosis progression in apolipoprotein E–deficient (ApoE⁻/⁻) and LDLR⁻/⁻ murine models fed a high-fat diet. An adeno-associated viral (AAV) vector was used to deliver a liver-specific CRISPR-Cas9 system targeting exon 1 of Pcsk9. Treated mice exhibited >90% reduction in hepatic Pcsk9 expression, accompanied by sustained reductions in serum PCSK9 and LDL-C levels. En face and histologic analyses revealed significant attenuation of atherosclerotic plaque burden in the aortic arch and root. Inflammatory markers such as IL-6 and VCAM-1 were also decreased, indicating reduced vascular inflammation. No off-target effects or hepatotoxicity were observed in genome-wide assays and liver function testing. Longitudinal assessment showed maintenance of lipid-lowering and anti-atherosclerotic effects for at least 24 weeks post-treatment. Conclusion: CRISPR-Cas9–mediated knockout of PCSK9 effectively reduces LDL-C and atherogenesis in murine models without detectable adverse effects. These findings support the feasibility of in vivo gene editing as a durable therapeutic approach for hypercholesterolemia and atherosclerotic cardiovascular disease. Future studies are warranted to optimize vector delivery, assess immunogenicity, and evaluate long-term safety in large animal models before clinical translation.