Early missed abortion is associated with villous angiogenesis via the HIF-1α/VEGF signaling pathway

PURPOSE: To analyze the effects of the hypoxia-inducible factor 1-alpha (HIF-1α)/vascular endothelial growth factor (VEGF) signaling pathway on villous angiogenesis in early missed abortion. METHODS: Immunohistochemical assays were performed to detect the expression of micro-vessel density (MVD), HIF-1α, and VEGF in villous tissue samples from 30 missed abortions and 30 elective abortions in early pregnancy. We further analyzed the correlation between HIF-1α/VEGF and MVD. HTR8/SVneo cells were cultured under hypoxic (1%) or normoxic (20%) conditions, tube formation was investigated, and protein and mRNA level of HIF-1α/VEGF were determined using western blot and qRT-PCR. Finally, HIF-1α was knocked down with siRNA introduced into HTR8/SVneo cell line under hypoxia, and HIF-1α/VEGF expression and HTR8/SVneo tube formation were investigated. RESULTS: The expression of HIF-1α, VEGF, and MVD was lower in the missed abortion than in the elective abortion group. Correlational analysis showed that the expression of HIF-1α and VEGF was positively correlated with MVD in both groups. The levels of HIF-1α/VEGF mRNA and protein in HTR8/SVneo cells were significantly enhanced under hypoxia. HIF-1α knockdown with siRNA inhibited HIF-1α/VEGF mRNA and protein levels of HTR8/SVneo cells induced by hypoxia. Tube formation of HTR8/SVneo cells was significantly enhanced in hypoxic culture and was inhibited by HIF-1α knockdown with siRNA. CONCLUSIONS: Our results reveal a novel role for HIF-1α/VEGF in regulating villous angiogenesis in early pregnancy and suggest that it may be a novel biomarker for missed abortion.