Morphological Study of Effects of Oxidized Low Density Lipoprotein on Three Dimensionally Constructed Vascular Wall

ABSTRACT

PURPOSE: The purpose of this experiment was to study the effects of Ox-LDL (oxidized low density lipoprotein) and Ox-VLDL (oxidized very low density lipoprotein) with or without probucol treatment on the proliferation of human vascular endothelial cells (EC) which were three dimensionally constructed vascular wall model. METHOD: The thiobarbituric acid reactive substance content of LDL and VLDL oxidized by incubation with copper irons was consistently greater than 10 nM malondialdehyde (MDA)/mg protein compared with less than 3 nM MDA/mg for unmodified lipoprotein immediately after isolation. On agarose gel electrophoresis, Ox-LDL and Ox-VLDL were shown to have greater cationic charge than unmodified lipoprotein. RESULT: In Ox-LDL stimulated ECs, the cellular enzymatic activity was markedly decreased in 50 mug/ml concentration of Ox-LDL and was protected by 10 nM probucol. And in Ox-VLDL stimulated ECs, the cellular enzymatic activity was markedly decreased in 25 and 50 mug/ml concentration of ox-VLDL and was not protected by 10 nM probucol. On scanning electron microscopy (SEM) and transmission electron microscopy (TEM), endothelial layers of control, unmodified LDL and unmodified VLDL groups showed similar appearance. But in Ox-LDL and Ox-VLDL groups, cellular edema, loosened cell-to-cell contact and loss of microvilli were shown on SEM, and marked cellular edema, distortion of cell membrane, loss of intracellular organelles and destruction of nulcleus were shown on TEM. And the protective effect of probucol was definite in Ox-LDL group but in 25 and 50 mug/ml concentration of Ox-VLDL group, there were no protective effects of probucol. CONCLLUSION As a conclusion, three dimensionally constructed vascular wall model is to be a good experimental model for vascular research. And Ox-LDL and Ox-VLDL have toxic effects on vascular endothelial cell layer and its toxic effects are partially prevented by probucol.