Expression of vascular endothelial growth factor receptors 1, 2 and 3 in placentas from normal and complicated pregnancies.

Extensive angiogenesis and invasion of the maternal decidua by trophoblasts are essential for the development and function of the placenta. Vascular endothelial growth factors (VEGF), placenta growth factor (PlGF) and their receptors VEGFR-1/Flt-1, VEGFR-2/KDR and VEGFR-3/Flt4 have important roles in vasculogenesis and angiogenesis. We have studied the localization of these proteins by immunohistochemistry and Western blotting in the placenta and of PlGF in maternal serum, and their association with diabetes, pre-eclampsia, fetal growth restriction (FGR) and fetal alcohol syndrome (FAS). VEGFR-1 and VEGFR-3 were detected mainly in the syncytiotrophoblastic layer whereas VEGFR-2 was detected in the vascular endothelial cells of the placenta. VEGFR-1, but not the other receptors, showed increased expression in placental syncytiotrophoblasts from 50% of patients with severe pre-eclampsia and FGR when compared with normal placentas. PlGF was undetectable in 38 of 44 samples of amniotic fluid of mothers with normal and complicated pregnancies. However, maternal serum PlGF concentrations were significantly lower in pre-eclamptic patients and in those with FGR when compared to diabetic women or healthy controls. These results suggest that low maternal serum PlGF and increased placental expression of its receptor VEGFR-1 are associated with pre-eclampsia and FGR.

Amniotic fluid--soluble vascular endothelial growth factor receptor-1 in preeclampsia.

OBJECTIVE: To measure the levels of the soluble receptor for the potent angiogenic agent vascular endothelial growth factor (VEGF) in amniotic fluid (AF) in healthy and complicated pregnancies, and compare them with levels of erythropoietin, another factor upregulated by hypoxia. METHODS: We assessed amniotic fluid from the second (n = 35, gestational weeks 14-19) and third (n = 29) trimesters of healthy women, and from the third trimesters of preeclamptic (n = 22) and diabetic women with (n = 11) or without preeclampsia (n = 34) and from women with fetal growth restriction (FGR) (n = 14) for soluble VEGF receptor-1 (VEGFR-1) by enzyme-linked immunosorbent assay. RESULTS: In early normal pregnancy, AF-soluble VEGFR-1 levels were higher (median 22 ng/mL, range 2.3-29.5 ng/mL) than in the third trimester (median 13 ng/mL, range 0.5-32 ng/mL; P < .05). In preeclamptic women during the third trimester, levels were higher (median 20 ng/mL, range 10.5-37 ng/mL; P < .05) than healthy controls. The lowest third-trimester levels were in diabetic women (median 11 ng/mL, range 0.5-27 ng/mL). In women with preeclampsia and diabetes, AF-soluble VEGFR-1 levels remained lower (median 13, range 6-32 ng/mL; P < .05) than in women with preeclampsia alone. Amniotic fluid levels of soluble VEGFR-1 in women with FGR (median 19.5 ng/mL, range 5-40 ng/mL) did not statistically differ from those of controls. The AF levels of soluble VEGFR-1 did not correlate with those of erythropoietin. Soluble VEGFR-1 was clearly detectable (median 14 ng/mL, range 9-22 ng/mL) in culture media from placental biopsies (n = 20). CONCLUSION: Preeclampsia is associated with increased levels of soluble VEGFR-1, which are independent of erythropoietin, another hypoxia-inducible factor.