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 (PIGF) 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 PIGF 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. VECFR-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. PIGF was undetectable in 38 of 44 samples of amniotic fluid of mothers with normal and complicated pregnancies. However, maternal serum PICF 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 PIGF and increased placental expression of its receptor VEGFR-1 are associated with pre-eclampsia and FGR.