| Atherosclerosis is a cardiovascular disease that is the leading cause of death in the United States. It is characterized by thickening of the arterial wall due to the accumulation of lipids, macrophages, smooth muscle cells, necrotic debris, calcifications, thrombosis and/or hematoma, which together form what is known as a plaque. Clinical events most commonly occur from plaque occlusions or ruptures. Although some factors affecting a plaque's vulnerability to rupture are known, it is not clear whether calcifications increase or decrease the probability of rupture. However, evidence suggests that calcifications affect the functionality and remodeling of arteries and sometimes intervene in the treatment of diseased arteries.;To better access how calcifications affect plaque vulnerability, arterial remodeling, and the treatments for atherosclerosis, it is imperative to learn more about the composition and physical properties of atherosclerotic calcifications. Hence, the objective of the present study is to further characterize atherosclerotic calcifications. The elastic mechanical properties were measured using nanoindentation for future use in finite element models; the composition of calcifications was analyzed using Fourier transform infrared (FTIR) spectroscopy to ascertain the similarities and differences in the biomineralization process of bone and atherosclerotic calcifications; nanoindentation was coupled with FTIR to determine structure-property relationships; and micro-computed tomography (muCT) was used to determine the mineral-density distribution of atherosclerotic calcifications in order to evaluate general calcification-growth patterns.;In the nanoindentation study, improved sample-preparation techniques narrowed the range of reduced elastic moduli as compared to a previous study. In addition, the coupling of nanoindentation to FTIR suggested that, as with other calcified materials, an increase in mineral content increases the elastic modulus. Additional FTIR studies revealed that, although the biomineralization processes of bone and atherosclerotic calcifications may produce a similar mineral phase, other factors can raise the mineral content of atherosclerotic calcifications and make its mineral slightly more crystalline. The muCT study revealed that calcification formation may occur in complex growth patterns or in clearly concentric or sedimentary-like depositions.;Together, the results obtained in the present study provide initial information about the mechanical properties of calcifications and yield important clues about the development and progression of atherosclerotic calcifications. |
