Isolation and in-vitro oxidation of human low density lipoproteins

Abstract

The role of low density lipoproteins (LDL) in the pathogensis of atherosclerosis has been gaining increasing importance. It is well accepted that LDL in their modified (i.e. oxidised) forms are no longer recognised by LDL-receptors, but are taken up by arterial wall cells, especially by macrophages, in a non-regulated manner through the so-called scavenger-receptor pathway. This process leads to the formation of foam cells, the hallmark of the atherosclerotic lesion. The oxidation can be induced in-vitro by incubating LDL with cultured cells of the arterial wall like endotherial cells, smooth muscle cells or monocytes/macrophages. A standardised oxidation can be achieved by incubating LDL with divalent metal ions like copper or iron. LDL modified by this method was found to have comparable physicochemical properties; and the copper-induced invitro oxidation of LDL has become a well established frequently used method. The kinetics of copper-induced LDL-oxidation can be monitored continuously by measuring the increase of the 234nm absorption of the developing conjugated dienes. The degree of oxidation can also be quantified by measuring the thiobarbituric acid reactive substances(TBARS) or by electrophoresis. LDL modified by this method was shown to be good tool for further in-vitro and also in-vivo investigations.

Keywords

• ldl
• oxidation
• atherosclerosis