| Objective: Investigate the number and function of the circulating endothelial progenitor cells (EPCs) from different aging populations to learn the relationship between age and EPCs levels.Methods: EPCs were isolated by Ficoll density gradient centrifugation from umbilical cord blood of healthy neonatal(n=20),or peripheral blood of healthy adult who were younger than 60(n=20) and peripheral blood of healthy elder who were older than 60(n=20).After in vitro cultivation, differentiating EPCs were identified as adherent cells double positive for Dil-acLDL and FITC-UEA-1 by direct fluorescent staining under a laser scanning confocal microscope. EPCs were further documented by demonstrating the expression of VEGFR-2,CD34 and AC133 with flow cytometry. EPCs proliferation was assayed by MTT assay,and migration was assayed by modified Boyden chamber assay. EPCs adhesion was performed by replating them on fibronectin-coated dishes. stromal cell-derived factor- l(SDF-1) in the cell culture supernatant were determined by ELISA for EPCs ability of secretion.Results: The number of EPCs from neonatal (203.0±20.7/×200 field ) is significantly increased than middle age group (62.5±10.6/×200 field,p<0.001 ) or elder groupis (44.6±9.1 /×200 field p<0.001), and the number of EPCs of middle age is more than elder (62.5±10.6vs44.6±9.1/×200,p<0.05). In addition, the functional activities of EPCs such as proliferation,migration and adhesion from neonatal is significantly better than the other two groups(p<0.001), and the EPCs capacities of proliferation ,migration from the middle age is better than old ones(p<0.05),but the capacity of adhesion is similar with old ones. The release of stromal cell-derived factor-1 into the cell culture from the three groups is separately (258.65±30.51), (131.94±20.43), (125.58±18.50)pg/ml , neonatal secretion is higher than the others(p<0.001) and the middle age is higher than old ones(p<0.05).Conclusion: The number of circulating EPCs of the neonatal is as much as 3.2 times more than the middle age,and the number is as much as 4.5 times than old ones.The number of EPCs decrease with the increase of age,and while the functional activities of EPCs such as proliferatiom,adhesion,migration and secretion also decrease with the increase of age.
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