Objective To construct human recombinant lentiviral expression vector of microRNA-210 (miR-210)and to explore the over-expression of miR-210 on the capillary formation in human umbilical vein endothelial cells 12 (HUVE-12). Methods The recombinant lentiviral expression vector of pGCSIL-green fluorescent protein (GFP)-pre-miR-210 wasconstructed by molecular cloning and transfected to HUVE-12 (LV-miR-210-GFP group), only pGCSIL-GFP was transfectedas control group (LV-GFP group). The miR-210 expression activity was evaluated by GFP reporter through fluorescencedetection and real-time fluorescent quantitative PCR. The ephrinA3 protein expression was measured by flow cytometry. Theconcentration of vascular endothelial growth factor (VEGF) in culture supernatant was determined by ELISA. The cells werecultured in 96-well culture plate coated with Matrigel to assess the abil ity of capillary formation. Results The recombinantplasmid pGCSIL-GFP-pre-miR-210 was confirmed by restriction endonuclease analysis and DNA sequencing. Fluorescencedetection showed that the fluorescence intensity of GFP was highest between 48 and 72 hours after transfection. Real-timefluorescent quantitative PCR showed that the miR-210 expression of LV-miR-210-GFP group was 9.72 times higher than thatin LV-GFP group (t= —11.10，P=0.00). Flow cytometry analysis showed that the positive cell rate of enphrinA3 in LV-miR-210-GFP group (12.52% ± 0.67%) was significantly lower than that in LV-GFP group (73.22% ± 1.45%) (t= —66.12，P=0.00).The concentration of VEGF in supernatant in LV-miR-210-GFP group was significantly higher than that in LV-GFP group[(305.29 ± 16.52) pg/mL vs. (42.52 ± 3.11) pg/mL, t= —27.06，P=0.00]. In vitro capillary-l ike formation assay showed that thenumber of capillaries was significantly larger in LV-miR-210-GFP group than in LV-GFP group (17.33 ± 6.33 vs. 6.33 ± 2.33,t= —2.83，P=0.04). Conclusion The recombinant lentiviral expression vector of miR-210 is constructed successfully andHUVE-12 over-expressing miR-210 can significantly increase the capillary formation, which facil itates further study on themolecular functions of miR-210 in angiogenesis.