Effects of oxidized low density lipoprotein on the growth of human artery smooth muscle cells.
BACKGROUND
Studies have shown that oxidized low density lipoprotein (ox-LDL) promotes the pathogenesis and development of atherosclerosis (AS), and that the proliferation, migration and phenotype alteration of vascular smooth muscle cells (vSMCs) into foam cells are critical changes in AS. It is proposed that ox-LDL might play a novel role in the pathologic process of vSMCs. The present study was performed ex vivo to investigate the effects of ox-LDL on the growth of cultured human vSMCs.


METHODS
Using NaBr density gradient centrifugation, LDL from human plasma was isolated and purified. ox-LDL was produced from LDL after being incubated with CuSO4. ox-LDL was then added to the culture medium at different concentrations (25 microg/ml, 50 microg/ml, 75 microg/ml, 100 microg/ml, 125 microg/ml, and 150 microg/ml) for 7 days. The influence of ox-LDL on vSMC growth was observed from several aspects as growth curve, mitosis index, lipid staining, and in situ determination of apoptosis. The digital results were analyzed with SPSS 10.0.


RESULTS
The ox-LDL produced ex vivo had a good purity and optimal oxidative degree, which was similar to the intrinsic ox-LDL in atherosclerotic plaque. ox-LDL at a concentration of 25 microg/ml demonstrated the strongest proliferation. At the concentration of 125 microg/ml, ox-LDL suppressed the growth of vSMCs. At concentrations of 25 microg/ml and 50 microg/ml, ox-LDL presented powerful mitotic trigger. When the concentration of ox-LDL increased, the mitotic index of vSMCs decreased gradually. ox-LDL induced more foam cells from vSMCs with rich intracellular lipid accumulation at concentrations of 25 microg/ml and 50 microg/ml. ox-LDL at higher concentrations induced more apoptotic vSMCs.


CONCLUSIONS
ox-LDL at lower concentrations may trigger proliferation and phenotype alteration into foam cells of vSMCs, and at higher concentrations it may induce apoptosis in vSMCs. ox-LDL plays an important role in the pathogenesis and development of atherosclerosis by its effect on vSMCs proliferation, phenotype alteration and apoptosis.
Zhao
Gao-feng
GF
Department of Thoracic Surgery, First Teaching Hospital, Zhengzhou University, Zhengzhou 450052, China.
Seng
Jing-jing
JJ
Zhang
Hua
H
She
Ming-peng
MP
D017209:Apoptosis / Q000187:drug effects; D050197:Atherosclerosis / Q000209:etiology*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008077:Lipoproteins, LDL / Q000633:toxicity*; D008940:Mitotic Index; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects*; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects*
D008077:Lipoproteins, LDL; C099252:oxidized low density lipoprotein