[show abstract][hide abstract] ABSTRACT: Optical coherence tomography (OCT) is a high resolution imaging technique used to assess superficial atherosclerotic plaque morphology. Utility of OCT may be enhanced by contrast agents targeting molecular mediators of inflammation.
Microparticles of iron oxide (MPIO; 1 and 4.5 μm diameter) in suspension were visualized and accurately quantified using a clinical optical coherence tomography system. Bound to PECAM-1 on a plane of cultured endothelial cells under static conditions, 1 μm MPIO were also readily detected by OCT. To design a molecular contrast probe that would bind activated endothelium under conditions of shear stress, we quantified the expression (basal vs. TNF-activated; molecules μm(-2)) of VCAM-1 (not detected vs. 16 ± 1); PECAM-1 (132 ± 6 vs. 198 ± 10) and E-selectin (not detected vs. 46 ± 0.6) using quantitative flow cytometry. We then compared the retention of antibody-conjugated MPIO targeting each of these molecules plus a combined VCAM-1 and E-selectin (E+V) probe across a range of physiologically relevant shear stresses. E+V MPIO were consistently retained with highest efficiency (P < 0.001) and at a density that provided conspicuous contrast effects on OCT pullback.
Microparticles of iron oxide were detectable using a clinical OCT system. Assessment of binding under flow conditions recommended an approach that targeted both E-selectin and VCAM-1. Bound to HUVEC under conditions of flow, targeted 1 μm E+V MPIO were readily identified on OCT pullback. Molecular imaging with OCT may be feasible in vivo using antibody targeted MPIO.
[show abstract][hide abstract] ABSTRACT: Our aim was to determine the effects of high-dose (2 g) nicotinic acid (NA) on progression of atherosclerosis and measures of vascular function.
NA raises high-density lipoprotein cholesterol (HDL-C) and reduces low-density lipoprotein cholesterol and is widely used as an adjunct to statin therapy in patients with coronary artery disease. Although changes in plasma lipoproteins suggest potential benefit, there is limited evidence of the effects of NA on disease progression when added to contemporary statin treatment.
We performed a double-blind, randomized, placebo-controlled study of 2 g daily modified-release NA added to statin therapy in 71 patients with low HDL-C (<40 mg/dl) and either: 1) type 2 diabetes with coronary heart disease; or 2) carotid/peripheral atherosclerosis. The primary end point was the change in carotid artery wall area, quantified by magnetic resonance imaging, after 1 year.
NA increased HDL-C by 23% and decreased low-density lipoprotein cholesterol by 19%. At 12 months, NA significantly reduced carotid wall area compared with placebo (adjusted treatment difference: -1.64 mm(2) [95% confidence interval: -3.12 to -0.16]; p = 0.03). Mean change in carotid wall area was -1.1 +/- 2.6 mm(2) for NA versus +1.2 +/- 3.0 mm(2) for placebo. In both the treatment and placebo groups, larger plaques were more prone to changes in size (r = 0.4, p = 0.04 for placebo, and r = -0.5, p = 0.02 for NA).
In statin-treated patients with low HDL-C, high-dose modified-release NA, compared with placebo, significantly reduces carotid atherosclerosis within 12 months. (Oxford Niaspan Study: Effects of Niaspan on Atherosclerosis and Endothelial Function; NCT00232531).
Journal of the American College of Cardiology 11/2009; 54(19):1787-94. · 14.09 Impact Factor
[show abstract][hide abstract] ABSTRACT: We aimed to develop and validate a model of angioplasty and stenting in mice that would allow investigation of the response to stent injury using genetically modified mouse strains.
Aortic segments from either C57BL/6 wild-type or atherosclerotic ApoE-KO mice underwent balloon angioplasty alone or balloon angioplasty and stenting with a 1.25x2.5 mm stainless steel stent. Vessels were carotid-interposition grafted into genetically identical littermate recipients and harvested at 1, 7, 14, or 28 days. In wild-type mice, stenting generated an inflammatory vascular injury response between days 1 to 7, leading to the development of neointimal hyperplasia by day 14, which further increased in area by day 28 leading to the development of in-stent stenosis. Uninjured vessels and vessels injured by balloon angioplasty alone developed minimal neointimal hyperplasia. In stented ApoE-KO mice, neointimal area at 28 days was 30% greater compared with wild-type mice.
By reproducing important features of human stenting in atherosclerotic mice, we provide the potential to investigate molecular pathways and evaluate novel therapeutic targets for stent injury and restenosis.