Expression of vascular endothelial growth factor and placenta growth factor in human placenta.

Normal development and function of the placenta requires invasion of the maternal decidua by trophoblasts, followed by abundant and organized vascular growth. Little is known of the significance and function of the vascular endothelial growth factor (VEGF) family, which includes VEGF, VEGF-B, and VEGF-C, and of placenta growth factor (PIGF) in these processes. In this study we have analyzed the expression of VEGF and PIGF mRNAs and their protein products in placental tissue obtained from noncomplicated pregnancies. Expression of VEGF and PIGF mRNA was observed by in situ hybridization in the chorionic mesenchyme and villous trophoblasts, respectively. Immunostaining localized the VEGF and PIGF proteins in the vascular endothelium, which was defined by staining for von Willebrand factor and for the Tie receptor tyrosine kinase, an early endothelial cell marker. VEGF-B and VEGF-C mRNAs were strongly expressed in human placenta as evidenced by Northern blot analysis. These data imply that VEGF and PIGF are produced by different cells but that both target the endothelial cells of normal human term placenta.