LOCALIZATION OF PLACENTA GROWTH-FACTOR (P1GF) IN HUMAN TERM PLACENTA

Placenta growth factor (PlGF) is a growth factor which belongs to the vascular endothelial growth factor (VEGF) family and is known to bind to the fms-like tyrosine kinase receptor (flt-1). Using Western blot a nalysis a 50 kDa band was identified in placental protein extract whic h corresponded to PlGF homodimer. Immunoreactive PlGF was localised to the vasculosyncytial membrane and in the media of large blood vessels of the placental villi, while staining within the mesenchyme was weak and diffuse. There was moderate staining for PlGF in discrete cells i n the chorion and no staining in the epithelial layer of the amnion. T he maternal decidual cells showed strong staining for PlGF immunoreact ive protein. PlGF mRNA was predominantly expressed by the vasculosyncy tial membrane of villous trophoblast, whilst there was no apparent exp ression of PlGF mRNA within the villous mesenchyme. These results sugg est that PlGF may be an important paracrine factor for vascular endoth elial cells in placental angiogenesis and an autocrine mediator of tro phoblast function.