Objective    To observe the effect of estradiol (E

2

) on apoptosis of endothelial progenitor cells (EPC) and in vitro neovascularization.     Methods    Bone marrow mononuclear cells (MNC)

harvested by density gradient centrifugation

were double-stained with FITC-agglutinin 1 and DiI-acetylated low density lipoprotein fluorescence and analyzed by flow cytometry. Seven days after culture

MNC were divided into control group

0.01

μmol/L E

2

group

0.1 μmol/L  group and 1 μmol/L E

2

group. After treated with E

2

at the concentrations of 0.01

0.1

and 1 μmol/L

apoptosis of EPC and in vitro neovascularization in experimental group were detected with a flow cytometer.     Results     E

2

used at the concentrations of 0.01

0.01

and 1 μmol/L

promoted in vitro tube formation in experimental group and control group (2.91±0.70

4.04±0.66 and 4.73±0.48 vs 2.13±0.59)

and apoptosis of EPC in experimental group decreased (0.24±0.01 and 0.21±0.02 vs 0.29±0.02 and 0.29±0.02

P0.01).     Conclusion     E

2

can inhibit apoptosis of EPC and promote in vitro neovascularization.