OBJECTIVETo investigate the influence of hypoxia on the proliferation and activity of human umbilical vein vascular endothelial cells (EA. hy926).

METHODSEA. hy926 cells were cultured in vitro and divided into normal control and hypoxia groups. The cells in hypoxia group were placed into hypoxic jar and treated with mixed gases(94% N2 +5% CO2 + 1% O2) for 1,3,6 and 12 hours. Then the total proteins were extracted for the determination of the expression of vascular endothelial growth factor (VEGF) and proliferation cell nuclear antigen (PCNA). The cell cycle and growth curve were determined with flow cytometry and MTT method, respectively.

RESULTSThe expression of PCNA protein began to increase at 3 post-hypoxia hour (PHH), peaked at 6 PHH, but without obvious difference compared with that at 12 PHH. The expression of VEGF began to increase at 1 PHH, peaked at 6 PHH, and decreased at 12 PHH, though it was still markedly higher than that of normoxia at 12 PHH. MTT results showed that the cell activity began to increase at 1 PHH, and it was still to increased at 3 PHH, then decreased at 6 PHH, and it was lower than that in control group at 12 PHH. The number of cells in G0/G1 phase was decreased, but the cells in S and G2/M phase was increased at 1, 3, 6 PHH when compared with those in normal controls. The proliferation index (PI) of cells in hypoxia group at 1PHH (43 +/- 9)%, 3PHH (39 +/- 11)%, 6 PHH (40 +/- 11))% were higher than that before hypoxia (32 +/- 9)% and 3 (39 +/- 11) % and 6 hours (40 +/- 11)% after hypoxia (P < 0.05). The PI was obviously lower at 12 PHH (27 +/- 4))% compared with that of cells under normoxic condition (P < 0.05).

CONCLUSIONShort-term hypoxia is beneficial to promote the proliferation of the cells, but this effect will be inhibited with the prolongation of hypoxia.