Iron and copper promote modification of low density lipoprotein by human arterial smooth muscle cells in culture.

Modification of low density lipoproteins by human arterial smooth muscle cells was characterized by increased electrophoretic mobility and increased content of malondialdehyde-like oxidation products reactive with thiobarbituric acid. Lipoprotein modification was promoted by micromolar concentrations of iron or copper in the culture medium and was metal ion concentration- and time-dependent. The ability of diverse media to promote smooth muscle cell-mediated low density lipoprotein modification correlated with their iron concentration. Therefore, metal ion concentration of culture media contributes substantially to low density lipoprotein modification in vitro. Human monocyte-derived macrophages took up and esterified the cholesterol from modified low density lipoprotein more extensively than from native low density lipoprotein. Metal ion-mediated modification of low density lipoprotein may be a contributing factor to the pathogenesis of arteriosclerosis.