ATHEROSCLEROSIS SEVERITY AFFECTS ARTERIAL REMODELING AFTER THE CAROTID ANGIOPLASTY

Highlights In the examined human stented internal carotid artery sample, we identified significant differences in remodeling patterns between the initially intact intima and atherosclerotic plaque area. Severe restenosis in the initially intact intima was characterized by intensive neutrophilic infiltration, proliferation of vascular smooth muscle cells and fibroblasts, active extracellular matrix remodeling, and immature microvessels. Moderate restenosis in the atherosclerotic plaque area was characterized by the absence of neutrophils, notable macrophage infiltration, and mature microvessels. Abstract Aim. To perform a histological analysis of arterial remodeling after the carotid angioplasty depending on the extent of atherosclerosis before the surgery. Methods. Here we examined human internal carotid artery excised during carotid endarterectomy which has been performed because of severe in-stent restenosis. The artery was sectioned into segments with initially intact intima (n = 3) and segments with atherosclerotic plaque (n = 3). Visualization was performed using backscattered scanning electron microscopy (EM-BSEM) after staining the segments with heavy metals, embedding them into epoxy resin, grinding and polishing of embedded specimens, and sputter coating the samples with carbon. We further assessed neointimal thickness, extracellular matrix state, microvessel parameters (total and mean lumen area, vessel density by area and quantity, presence of blood cells within and surrounding vessels), cellular composition, and immune cell infiltration patterns. Results. Significant differences in patterns of arterial remodeling were observed between the initially intact intima and atherosclerotic plaque area. Restenotic neointima in initially intact regions was thick, loose and disorganized and was notable for high cellular density, severe neutrophilic infiltration, and immature microvessels (i.e., signs of acute inflammation). In contrast, atherosclerotic plaque areas had moderate degree of restenosis, dense neointima, mature microvessels, and macrophage infiltration, altogether suggestive of chronic inflammation. Morphometric analysis revealed a trend toward increased neointimal thickness in the initially intact intima; however, microvascular parameters did not differ significantly between the intact and atherosclerotic areas. Conclusion. The initial state of the carotid artery wall affects the neointimal composition, extracellular matrix remodeling, angiogenesis and inflammation patterns. Initially intact intima exhibited high reactivity associated with a severe restenosis, loose neointima formation, and acute inflammation. In contrast, plaque areas demonstrate more stable neointimal structure and features of chronic inflammation.