Abstract Body (Do not enter title and authors here): Background
The current unmet needs for aspirin usage in atherosclerosis lie in its short half-life and narrow indication for anti-platelet effects. Daily aspirin intake is mandatory, and the anti-inflammatory effects of aspirin for atherosclerosis have not successfully translated to clinical practice. Nanoparticles remain in circulation for 2-3 days, with a large portion being cleared by splenic monocytes, which are known to inherently target inflamed sites.

Hypothesis
By altering the pharmacokinetics of aspirin through loading into nanoparticles, aspirin-nanoparticles can exert prolonged anti-platelet effects and target atherosclerosis sites via monocyte carriers for anti-inflammatory effects, resulting in dual therapies.

Methods
Splenic monocytes were loaded with aspirin-liposomes and co-cultured with endothelial cells or platelets to examine the interactions between them using high-resolution time-series microscopy. Prolonged anti-platelet effects and targeted anti-inflammatory effects of aspirin were validated in intact mice and hindlimb ischemia models, respectively. Furthermore, the dual therapies of aspirin-liposomes were validated in an atherosclerotic mouse model created by partial carotid ligation and a western diet in apoE gene knock-out mice.

Results
When splenic monocytes were loaded with aspirin-liposomes, they emitted extracellular vesicles (EVs) loaded with aspirin towards endothelial cells or platelets. As inflamed cells upregulate caveolin expression, they uptake an increased amount of transferred EVs compared to non-inflamed cells. Additionally, aspirin-liposomes showed prolonged circulation time and increased splenic accumulation compared to aspirin itself, resulting in prolonged anti-platelet effects (>7 days) and targeted anti-inflammatory effects at inflamed sites. Compared to the daily oral aspirin group in the atherosclerosis model, the weekly intravenous aspirin-liposome group showed superior therapeutic effects, including attenuated systemic and local inflammation and patent lumen in atherosclerotic sites.

Conclusion
Aspirin-nanoparticles can exert prolonged anti-platelet effects combined with targeted anti-inflammatory effects, resulting in superior therapeutic effects on atherosclerosis.