Left ventricular (LV) remodeling after myocardial infarction (MI) causes heart failure. Although medical therapies including angiotensin converting enzyme inhibitors show inhibitory effects on post-infarct LV remodeling, the prognosis of patients with post-infarct heart failure is still poor. Accumulating evidence suggests that an inflammatory response is implicated in the process of post-infarct LV remodeling. Therefore, we hypothesized that anti-inflammatory therapy by nanoparticle-mediated monocyte/macrophage-targeting delivery of pitavastatin may protect the heart from post-infarct LV remodeling. Male C57BL/6 mice were subjected to permanent coronary ligation and pitavastatin-incorporating nanoparticles (Pitavastatin-NPs) were intravenously injected for 3 to 5 consecutive days. Pitavastatin-NPs were delivered to CD11b+ monocytes/macrophages, but not to cardiomyocytes. Treatment with Pitavastatin-NPs after establishment of MI attenuated post-infarct LV remodeling accompanied by a reduction of monocytes/macrophages in the heart, whereas pitavastatin solution treatment did not. Pitavastatin-NPs inhibited mobilization of monocytes from the spleen after MI. In mice after splenectomy, Pitavastatin-NPs still decreased the number of monocytes/macrophages in the infarcted heart and inhibited post-infarct LV remodeling. Nanoparticle-mediated delivery of pitavastatin to monocytes/macrophages may be a novel therapeutic strategy to protect the heart from post-infarct LV remodeling. Inhibition of monocyte mobilization from the bone marrow is one of the major mechanisms by which Pitavastatin-NPs attenuated post-infarct LV remodeling.
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