Oxidized low-density-lipoprotein triggers programmed death of endothelial cells

Incubation of bovine aortic as well as human umbilical vein endothelial cells with either oxidized or native low-density-lipoprotein in the presence of trace amounts of copper induced morphological changes of the cells and chromatin fragmentation characteristic for programmed cell death. Shrinkage of cells was evident after 6 to 8 hours of incubation and clearly preceded release of lactate dehydrogenase as a marker of cell permeability. Condensation of nuclear chromatin and internucleosomal cleavage was demonstrated by Hoechst staining and gel electrophoresis, respectively. Thus, by inducing active death of endothelial cells oxidized low-density-lipoprotein might negatively influence tissue homeostasis of the endothelium and thereby promote the development of atherosclerotic plaques.