Effects of ox-LDL on number and activity of circulating endothelial progenitor cells.
BACKGROUND
Endothelial dysfunction is thought to play a crucial role in the pathogenesis of atherosclerosis induced by ox-LDL. Recently, a variety of evidence suggested that endothelial progenitor cells (EPCs) participated in neovascularization and reendothelialization. However, effects of ox-LDL on EPCs number and activity are ill understood.


METHODS
Total mononuclear cells (MNCs) were isolated from peripheral blood by Ficoll density gradient centrifugation, and then the cells were plated on fibronectin-coated culture dishes. After 7 days culture, attached cells were stimulated with ox-LDL (to make a series of final concentrations: 25 microg/mL, 50 microg/mL, 100 microg/mL, 200 microg/mL), native LDL (100 microg/mL) or vehicle control for the respective time points (6 h, 12 h, 24 h and 48 h). EPCs were characterized as adherent cells double positive for DiLDL-uptake and lectin binding by direct fluorescent staining under a laser scanning confocal microscope. EPCs were further documented by demonstrating the expression of KDR, VEGFR-2 and AC133 with flow cytometry. Proliferation, migration and in vitro vasculogenesis activity of EPCs were assayed by MTT assay, modified Boyden chamber assay and in vitro vasculogenesis kit, respectively. EPCs adhesion assay was performed by replating those on fibronectin-coated dishes, and then counting adherent cells.


RESULTS
Incubation of isolated human EPCs with ox-LDL decreased the number of EPCs in concentration-dependent manner, maximum at 200 microg/mL (approximately 70% reduction, P < 0.001). In time-course experiments performed with an ox-LDL concentration of 100 microg/mL, decrease of EPCs number became apparent at 12 hours and reached the maximum at 24 hours (approximately 50% reduction, P < 0.01). In addition, ox-LDL dose and time dependently impaired EPC proliferative, migratory, adhesive and in vitro vasculogenesis capacity.


CONCLUSIONS
The results of the present study defined a novel mechanism of action of ox-LDL: the reduction of EPCs with decreased functional activity.
Wang
Xingxiang
X
Department of Cardiovascular Diseases, The First Affiliated Hospital, Medical School of Zhejiang University, Hangzhou, Zhejiang Province, PR China. wangxx19730312@yahoo.com.cn
Chen
Junzhu
J
Tao
Qianmin
Q
Zhu
Junhui
J
Shang
Yunpeng
Y
D000328:Adult; D001772:Blood Cell Count; D002448:Cell Adhesion / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D003324:Coronary Artery Disease / Q000473:pathology; D042783:Endothelial Cells / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D005434:Flow Cytometry; D006801:Humans; D008077:Lipoproteins, LDL / Q000138:chemical synthesis / Q000494:pharmacology*; D018919:Neovascularization, Physiologic / Q000187:drug effects; D013234:Stem Cells / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D013778:Tetrazolium Salts; D013844:Thiazoles
D008077:Lipoproteins, LDL; D013778:Tetrazolium Salts; D013844:Thiazoles; C099252:oxidized low density lipoprotein; C022616:thiazolyl blue