A Novel Mouse Model of Atherosclerotic Plaque Instability for Drug Testing and Mechanistic/Therapeutic Discoveries Using Gene and MicroRNA Expression Profiling

Abstract

A therosclerosis, a progressive, chronic, inflammatory disease with specific, localized manifestations in the arterial wall, is a major health burden and is predicted to become the leading cause of mortality and morbidity worldwide. 1,2 Complications of atherosclerosis, such as myocardial infarction (MI), which is the largest single cause of death in developed countries, are caused by inflammation-driven rupture of atherosclerotic plaques. 3A major hurdle in research on mechanisms of plaque rupture is the lack of appropriate mouse models which exhibit plaque rupture and lesion characteristics of vulnerable, unstable, and thus rupture-prone plaques as found in humans.4 Such characteristics most importantly include a thin and ruptured fibrous cap, plaque inflammation, neovascularization within the plaque (vasa vasorum), plaque hemorrhage, and intravascular (often occlusive) thrombus formation. 2,3,[5][6][7] In addition, an animal model of plaque instability/rupture should include responsiveness to pharmacological agents known to reduce the risk of plaque rupture in humans. 8,9 Currently discussed animal models of atherosclerosis typically represent a few but not the full combination of the characteristics seen in human unstable/ruptured plaques. [10][11][12][13][14] An animal model of New Methods in Cardiovascular Biology© 2013 American Heart Association, Inc. Rationale: The high morbidity/mortality of atherosclerosis is typically precipitated by plaque rupture and consequent thrombosis. However, research on underlying mechanisms and therapeutic approaches is limited by the lack of animal models that reproduce plaque instability observed in humans.Objective: Development and use of a mouse model of plaque rupture that reflects the end stage of human atherosclerosis. Methods and Results:On the basis of flow measurements and computational fluid dynamics, we applied a tandem stenosis to the carotid artery of apolipoprotein E-deficient mice on high-fat diet. At 7 weeks postoperatively, we observed intraplaque hemorrhage in ≈50% of mice, as well as disruption of fibrous caps, intraluminal thrombosis, neovascularization, and further characteristics typically seen in human unstable plaques. Administration of atorvastatin was associated with plaque stabilization and downregulation of monocyte chemoattractant protein-1 and ubiquitin. Microarray profiling of mRNA and microRNA (miR) and, in particular, its combined analysis demonstrated major differences in the hierarchical clustering of genes and miRs among nonatherosclerotic arteries, stable, and unstable plaques and allows the identification of distinct genes/miRs, potentially representing novel therapeutic targets for plaque stabilization. The feasibility of the described animal model as a discovery tool was established in a pilot approach, identifying a disintegrin and metalloprotease with thrombospondin motifs 4 (ADAMTS4) and miR-322 as potential pathogenic factors of plaque instability in mice and validated in human plaques. Conclusions:The newly described mouse mod...

Atherosclerotic Plaque Destabilization

“…71 Recently, a model of vulnerable plaque formation based on the induction of a tandem stenosis was proposed. 72 In this model, a high incidence of plaque disruption and intraplaque hemorrhage was observed. 72 As an alternative to surgical approaches, transgenic strategies are used to induce plaque destabilization.…”

“…72 In this model, a high incidence of plaque disruption and intraplaque hemorrhage was observed. 72 As an alternative to surgical approaches, transgenic strategies are used to induce plaque destabilization. The expression of the human diphtheria toxin receptor under the control of the SM22α promoter permitted specific induction of SMC apoptosis after toxin administration.…”

The roles of myeloperoxidase in coronary artery disease and its potential implication in plaque rupture

“…The imaging of MPO activity rather than phagocytes is likely to result in more specific localization of vulnerable plaques. MPO-Gd has also been shown to enhance regions aortic root inflammation in a mouse model of vasculitis [165]. Similarly, MPO-Gd has been successfully used to image aortic root inflammation in a mouse model of vasculitis [164].…”

Orthopedic surgery increases atherosclerotic lesions and necrotic core area in ApoE−/− mice

“…For instance, hemodynamic disturbances 27 , sympathetic nerve system activation 28 or enhanced platelet activity 29 are potential contributors to atherosclerotic lesion development and increased cardiovascular risk. Furthermore it would be interesting to test our findings in advanced mouse models to study actual plaque complications rather than atherosclerotic plaque development alone 30,31 .…”