Hypoxia-inducible factor-2alpha is involved in enhanced apoptosis in the placenta from pregnancies with fetal growth restriction.

The aim of the present study is to investigate whether hypoxia-inducible factors (HIF-1alpha, HIF-2alpha, HIF-1beta) are involved in enhanced apoptosis in the human placenta from pregnancies with fetal growth restriction (FGR). Placental samples were obtained from women with normal term pregnancy (n = 18) or from pregnancy with FGR (n = 12). Placenta apoptosis was assessed by the terminal deoxynucleotidyl transferase deoxy-UTP-nick end labeling (TUNEL) staining. The expressions of HIF-1alpha, HIF-2alpha, and HIF-1beta were examined by immunohistochemical analysis. Enhanced apoptosis was observed in the placenta from pregnancies with FGR compared with normal term placenta. The apoptosis index in FGR group (1.45 +/- 1.26%) was significantly higher than that in the normal control group (0.18 +/- 0.16%; P < 0.01). There were no significant differences in the intensity of the staining for HIF-1alpha and HIF-1beta expressions between two groups, while HIF-2alpha was overexpressed in the placenta from pregnancies with FGR group (P < 0.05). The upregulation of HIF-2alpha protein expression in the placenta from pregnancies with FGR may, at least in part, be involved in the increased placental apoptosis.