Hypoxia-induced increase in soluble Flt-1 production correlates with enhanced oxidative stress in trophoblast cells from the human placenta

• Published in: Placenta (Eastbourne) 2005-02, Vol.26 (2), p.210-217
• Main Authors: Li, H., Gu, B., Zhang, Y., Lewis, D.F., Wang, Y.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Cell Hypoxia - physiology; Cells, Cultured; Embryology: invertebrates and vertebrates. Teratology; Fetal membranes; Fundamental and applied biological sciences. Psychology; General aspects. Development. Fetal membranes; Heme Oxygenase (Decyclizing) - genetics; Heme Oxygenase (Decyclizing) - metabolism; Heme Oxygenase-1; Lipid Peroxides - metabolism; Oxidative Stress; Placenta Growth Factor; Pregnancy Proteins - genetics; Pregnancy Proteins - metabolism; RNA, Messenger - metabolism; Superoxide Dismutase - genetics; Superoxide Dismutase - metabolism; Trophoblasts - metabolism; Up-Regulation; Vascular Endothelial Growth Factor A - genetics; Vascular Endothelial Growth Factor A - metabolism; Vascular Endothelial Growth Factor Receptor-1 - genetics; Vascular Endothelial Growth Factor Receptor-1 - metabolism
• ISSN: 0143-4004; 1532-3102
• DOI: 10.1016/j.placenta.2004.05.004

Placental trophoblast cells (TCs) produce soluble Flt-1 (sFlt-1). Hypoxia induces placental oxidative stress and modulates trophoblast function. The aim of this study was to investigate whether hypoxia mediates TC sFlt-1 production and whether increased sFlt-1 production correlates with increased oxidative stress in placental TCs. Placentas were obtained immediately after delivery from normal pregnant women ( n=8). Placental TCs were isolated by Dispase digestion of villous tissue and purified by Percoll gradient centrifugation. Isolated TCs were cultured under normoxia (21% O 2: 5% CO 2/95% air) and hypoxia (2% O 2/5% CO 2/93% N 2) conditions for 3 days in vitro. TC productions of sFlt-1, VEGF, and PlGF were measured by enzyme-linked immunosorbent assay (ELISA). Lipid peroxide production and superoxide dismutase (CuZn-SOD) levels were evaluated. Messenger RNA expressions of Flt-1, VEGF and PlGF were determined by RT-PCR. Messenger RNA expressions for superoxide dismutase (CuZn-SOD) and heme oxygenase-1 (HO-1) were also determined. Data are expressed as mean ± SE. A p level less than 0.05 was considered statistically different. Our results show that sFlt-1 production was significantly increased by TCs cultured under hypoxia condition that correlates with increased lipid peroxide production. We also found that under hypoxia condition: (1) the ratio of PlGF/VEGF production was reversed; (2) the ratio of lipid peroxides to superoxide dismutase production was increased. The increased mRNA expressions for Flt-1 and VEGF and the decreased mRNA expression for PlGF in TCs were consistent with the protein productions under hypoxia condition. We concluded that upregulation of sFlt-1 and unbalanced PlGF/VEGF production associated with increased oxidative stress are consequences of hypoxia in placental TCs. Our results suggest that placental TCs are major sources of sFlt-1 and VEGF levels in the maternal circulation in women with preeclampsia.