AGE-RELATED INCREASE IN THE UPTAKE OF ACETYLATED LOW-DENSITY-LIPOPROTEIN INTO CULTURED ENDOTHELIAL-CELLS FROM RAT AORTA

A simple and reliable method for the separation of endothelial cells from the thoracic aorta of rats was established in the present study. The cultured endothelial cells separated by this improved explantation method showed typical characteristics of endothelial cells, morphology of cobblestone monolayer, immunoreactivity against antibodies to Von Willebrand's factor and angiotensin I converting enzyme, and the ability to uptake acetylated low density lipoprotein (LDL) labeled with 1,1'-dioctadecyl-1-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate (DiI-Ac-LDL). The purity of the cultured endothelial cells separated by this method was over 98%, and the cells were maintained in culture for 3-4 months. Age-related changes of the uptake of DiI-Ac-LDL into the endothelial cells were then estimated by using the cultured endothelial cells separated from the aortas of young (4-8 weeks old) and old (95-100 weeks old) rats. When fluorescent DiI-Ac-LDL-labeled endothelial cells were sorted and analyzed by a cell sorter, the fluorescence intensity of the cultured cells from old rats was stronger than that of the cells from young rats. Therefore, the present results show that the uptake of the acetylated LDL into the endothelial cells increases with rat aging, and suggest the age-related increase in the acetyl LDL receptor in the endothelial cells of the rat aorta.