Spatial Delivery of MicroRNA Inhibitor via Targeted Polyelectrolyte Complex Micelles to Treat Atherosclerosis.
Project Summary Atherosclerotic vascular disease and downstream tissue ischemia (heart attacks, strokes) remain the leading cause of morbidity and mortality among Americans. Atherosclerosis (thickening and hardening of vas- cular walls) develops preferentially at arterial sites of curvature and bifurcation where disturbed blood flow is prevalent; yet, current pharmacological treatments of atherosclerosis principally target ?systemic? risk factors such as high blood cholesterol. We believe targeted nanomedicine has unique potential to revolutionize future medical practice of atherosclerosis by correcting disease-causing molecular mechanisms ?regionally? in dis- eased blood vessels. Arterial wall-based therapy is attractive given the focal nature of atherosclerosis at predictable vascular sites. Disturbed flow increases endothelial permeability and promotes endothelial inflammation, leading to the subendothelial retention of low-density lipoprotein (LDL) cholesterol particles and monocytes accumulation. Lesion monocytes mature into macrophages and internalize lipoproteins. Excess cellular cholesterol effluxed from macrophages is transported by high density lipoproteins (HDL) to the liver for excretion through a process known as Reverse Cholesterol Transport (RCT). Inadequate RCT is associated with cholesterol-loaded mac- rophage ?foam cells?. Extensive studies suggest that inhibition of endothelial inflammation and promotion of macrophage cholesterol efflux are ideal strategies to prevent or regress atherosclerosis. Nevertheless, it re- mains extremely difficult to modulate these disease-causing molecular mechanisms ?spatially? in lesions. microRNAs (miRNAs) are critical gene regulators of cellular events related to atherosclerosis. Disturbed flow increases endothelial miR-92a to promote vascular inflammation while elevated miR-33a suppresses cho- lesterol efflux. The overall goal of this project is to develop a new nanomedicine-based therapeutic strategy against atherosclerosis, aiming to inhibit endothelial miR-92a and suppress macrophage miR-33a in a lesion- specific fashion. Our key premise is that this new strategy, if successful, could mitigate the tremendous health burden of atherosclerosis. Indeed, our preliminary data suggest that this can be done. We have employed tar- geting peptides against fibrin and Vascular Cell Adhesion Molecule 1 (VCAM-1) to drive active binding of nano- materials to atherosclerotic lesions and inflamed endothelia, respectively. Moreover, peptides against C-C chemokine receptor type 2 (CCR2) successfully delivered nanoparticles to lesion monocytes/macrophages. To address our overall goal, we hold two immediate objectives. First, we will refine and test a novel polyelectrolyte complex micelle system to deliver miR-92a inhibitor specifically to athero-susceptible endotheli- um. Second, this polyelectrolyte complex micelle will be reformulated to display peptides against lesion macro- phages to deliver inhibitors against miR-33a. These studies should further preclinical development, and per- haps eventual clinical testing, of a new therapeutic strategy to treat atherosclerosis, a still critically important disease process.