Nanoparticle-mediated delivery of pitavastatin inhibits atherosclerotic plaque destabilization/rupture in mice by regulating the recruitment of inflammatory monocytes

BACKGROUND- : Preventing atherosclerotic plaque destabilization and rupture is the most reasonable therapeutic strategy for acute myocardial infarction. Therefore, we tested the hypotheses that (1) inflammatory monocytes play a causative role in plaque destabilization and rupture and (2) the nanoparticle-mediated delivery of pitavastatin into circulating inflammatory monocytes inhibits plaque destabilization and rupture. METHODS AND RESULTS- : We used a model of plaque destabilization and rupture in the brachiocephalic arteries of apolipoprotein E-deficient (ApoE^-/-) mice fed a high-fat diet and infused with angiotensin II. The adoptive transfer of CCR2 ^+/+Ly-6C_high inflammatory macrophages, but not CCR2 ^-/- leukocytes, accelerated plaque destabilization associated with increased serum monocyte chemoattractant protein-1 (MCP-1), monocyte-colony stimulating factor, and matrix metalloproteinase-9. We prepared poly(lactic-co-glycolic) acid nanoparticles that were incorporated by Ly-6GCD11b⁺ monocytes and delivered into atherosclerotic plaques after intravenous administration. Intravenous treatment with pitavastatin-incorporated nanoparticles, but not with control nanoparticles or pitavastatin alone, inhibited plaque destabilization and rupture associated with decreased monocyte infiltration and gelatinase activity in the plaque. Pitavastatin-incorporated nanoparticles inhibited MCP-1-induced monocyte chemotaxis and the secretion of MCP-1 and matrix metalloproteinase-9 from cultured macrophages. Furthermore, the nanoparticle-mediated anti-MCP-1 gene therapy reduced the incidence of plaque destabilization and rupture. CONCLUSIONS- : The recruitment of inflammatory monocytes is critical in the pathogenesis of plaque destabilization and rupture, and nanoparticle-mediated pitavastatin delivery is a promising therapeutic strategy to inhibit plaque destabilization and rupture by regulating MCP-1/CCR2-dependent monocyte recruitment in this model.