The characteristics for the ex vivo expansion of the endothelial progenitor cells (EPCs) were explored. CD34+ cells were selected from umbilical cord blood mononuclear cells (MNC) by MiniMACS system, expanded under the same conditions as those for total MNC, coincubation of CD34+ and CD34- from the same donor for EPCs. In addition, the effects of vessel endothelial growth factor (VEGF) and passage on cell differentiation, expansion kinetics and apoptosis were examined. EPCs were determined and quantified by immunocytochemistry and flow cytometry. The results showed that both coculture of CD34+ and CD34- and total MNC led to a significant increase in the expansion of CD34+ cells as compared with CD34 enrichment (P < 0.05). There was a tendency toward decreased apoptosis in cultures when early passage was performed immediately after cord like structures appeared. VEGF had no significant effect on apoptosis (P > 0.05). These differentiated EPCs were positive for CD34+, von Willebrand factor (vWF), KDR, CD31 staining and phagocytized acetylated low-density lipoprotein (LDL). CD34+ cells accounted for (68.2 +/- 6.3)% of attaching (AT) cells at day 7 of culture. It was suggested the most efficient method to ex vivo expansion of EPCs was coculture of CD34+ and CD34- or total MNC. Early passage makes cell apoptosis rate decrease. VEGF had no significant effect on ex vivo expansion of EPCs.

To develop a more efficient antithrombotic way after coronary artery bypass grafting (CABG), the anticoagulant effects were compared of human tissue factor pathway inhibitor (TFPI) gene transfection and aspirin oral administration (traditional method) on vein grafts. An eukaryotic expression plasmid pCMV-(Kozak) TFPI was prepared. Animal model of carotid artery bypass grafting was constructed. In operation, endothelial cells of vein grafts in TFPI group and empty plasmid control group were transfected with pCMV-(Kozak) TFPI and empty plasmid pCMV respectively, while no transfection was conducted in aspirin control group. After operation, aspirin (2 mg.kg(-1).(-1)) was administered (i.g.) in aspirin control group. Three days later, grafts (n=10) were harvested for RT-PCR, Western blotting and immunohistochemical analyses of exogenous gene expression and for pathological, scanning electron microscopic observation of thrombus. Thirty days later, the patency rates of remnant grafts (n=10) were recorded by vessel Doppler ultrasonography. Human TFPI gene products were detected in gene transferred vein grafts. Three days later, thrombi were found in 7 animals of aspirin control group and in 8 animals of empty plasmid control group, but in only 1 of TFPI group (P<0.01). Thirty days later, 5 grafts were occluded in empty plasmid control group, but none of grafts was occluded in the other groups (P<0.05). The endothelial surfaces of grafts in both of the control groups were covered with aggregated erythrocytes and platelets, and it were not seen in TFPI group. It was suggested that the anticoagulant effects on vein grafts of human TFPI gene transfection are better than those of aspirin.
Administration, Oral ; Anticoagulants/*metabolism ; Aspirin/*administration & dosage ; Aspirin/metabolism ; Coronary Artery Bypass ; Disease Models, Animal ; Lipoproteins/*metabolism ; Plasmids/metabolism ; Tissue Transplantation/*methods ; Transfection ; Ultrasonography, Doppler/methods ; Veins/*transplantation ; Venous Thrombosis/metabolism

The characteristics for the ex vivo expansion of the endothelial progenitor cells (EPCs)were explored. CD34+ cells were selected from umbilical cord blood mononuclear cells (MNC) by MiniMACS system, expanded under the same conditions as those for total MNC, coincubation of CD34+ and CD34- from the same donor for EPCs. In addition, the effects of vessel endothelial growth factor (VEGF) and passage on cell differentiation, expansion kinetics and apoptosis were examined.EPCs were determined and quantified by immunocytochemistry and flow cytometry. The results showed that both coculture of CD34+ and CD34 and total MNC led to a significant increase in the expansion of CD34+ cells as compared with CD34 enrichment (P＜0.05). There was a tendency toward decreased apoptosis in cultures when early passage was performed immediately after cord like structures appeared. VEGF had no significant effect on apoptosis (P＞0.05). These differentiated EPCs were positive for CD34+, von Willebrand factor (vWF), KDR, CD31 staining and phagocytized acetylated low-density lipoprotein (LDL). CD34+ cells accounted for (68.2±6.3) % of attaching (AT)cells at day 7 of culture. It was suggested the most efficient method to ex vivo expansion of EPCs was coculture of CD34+ and CD34- or total MNC. Early passage makes cell apoptosis rate decrease.VEGF had no significant effect on ex vivo expansion of EPCs.