Atherosclerosis- and age-related multinucleated variant endothelial cells in primary culture from human aorta

Abstract

Endothelial cells were cultured from human aortas and inferior venae cavae of autopsied subjects ranging in age from infancy to 85 years. Endothelial cells in 32 of more than 100 attempted cultures were pure enough for evaluation. Emerged endothelial cells in primary culture were classified into two types: typical endothelium and variant endothelium. Typical endothelial cells were small, round to polygonal shaped, and were arranged uniformly. Their diameter ranged from 50 to 70 microns. Variant endothelial cells were larger, ranging from 100 to 200 microns in diameter, and giant endothelial cells measuring more than 250 microns in diameter were scattered among them. Variant endothelial cells were usually multinucleated and possessed endothelium-specific markers of vWF and Weibel-Palade bodies. No incorporation of [3H]thymidine was found in the nuclei of cultured variant endothelial cells. Although most cultured endothelial cells were of the typical type, variant endothelial cells were interspersed throughout the culture. The ratio of variant endothelial cells to typical cells correlated well with the severity of atherosclerosis, but less so with aging. The number of variant endothelial cells in cultures from inferior venae cavae was slight and constant throughout all age groups. The presence of multinucleated endothelial cells in in vivo aortas was confirmed by both scanning and transmission electron microscopy. They sometimes existed in colonies in the aortas from elderly subjects with intimal-thickened or advanced atherosclerotic lesions. These results indicate that variant endothelial cells were present in vivo and their ratio in primary culture reflected the in vivo population. It is likely that these cells were formed by adhesion of adjacent typical endothelial cells and that this process was affected more by atherosclerosis than by aging. Although it is not clear if the multinucleated variant cells were formed before the formation of atherosclerotic plaque or after the plaque formation, they will contribute to further development of atherosclerotic lesions, which in turn cause malfunction of the cell membrane. We suggest that there is a cyclic effect of these processes for multiplication of the variant endothelial cells and advancement of atherosclerotic lesions.