Flow cytometry analysis of atherosclerotic plaque cells from human carotids: a validation study

BACKGROUND: Atherosclerotic plaques are heterogeneous vascular lesions. Changes in cell plaque composition are fundamental events inside the plaque microenvironment that are strictly related to the clinical outcome of these lesions (organ damage). The knowledge of these modifications may help to better understand the pathophysiological mechanisms of atherosclerosis. METHODS: We report on a flow cytometry method to characterize and quantify the cell subpopulations in human atherosclerotic plaques. Cells were obtained from endarterectomy specimens after collagenase digestion. Both surface and intracytoplasmic antigens were labeled. RESULTS: Our data demonstrated that the method we described allowed the characterization of cell populations that compose the atherosclerotic plaque, avoiding contamination by tunica media smooth muscle cells and the noise of cellular debris. Moreover this validation study showed that about 50% of cells in the atherosclerotic plaques are inflammatory mononuclear cells (T lymphocytes and monocytes/macrophages). CONCLUSIONS: Reproducible quantitative methods for cell population characterization may increase the understanding of pathophysiological mechanisms responsible for plaque progression. The methodology herein described gave us the possibility of quickly calculating the relative amount of each cell population and studying both surface and intracellular markers to analyze the functional stage of the cells. The clinical correlation was not assessed in the present study, because we used a small patient group to validate the method, but should be the subject of further analyses in a larger patient population.