A novel flow cytometry-based quantitative monocyte adhesion assay to estimate endothelial cell activation in vitro

One of the earliest events in the development of atherosclerosis is endothelial activation, which is estimated in vitro at the functional level by quantifying monocyte adhesion. This involves the incubation of fluorescently labeled monocytes on top of cultured endothelial cells and quantifying the number of adhered monocytes. Currently, the quantification of adhered monocytes is done using microscopy or by lysing the cells and estimating the fluorescence. Here we present a novel flow cytometry-based method for the quantification of monocyte adhesion. This method could quantify the average number of monocytes adhered to a single endothelial cell after monocyte adhesion assay, and was also sensitive to the level of activation of endothelial cells. Flow cytometry-based quantification requires less time and effort compared with microscopy-based quantification.