Regulation of human villous trophoblast by insulin-like growth factors and insulin-like growth factor-binding protein-1

Abstract

Many studies have implicated the insulin-like growth factors (IGFs) and insulin-like growth factor-binding protein-1 (IGFBP-1) in the control of the feto–maternal interface of human pregnancy, but many of the data are from cell lines derived from primary trophoblast or from extravillous trophoblast. We have obtained highly enriched villous cytotrophoblast (VCT) from first trimester and term human placentae, and investigated the effects of IGF-I, IGF-II and phosphoisoforms of IGFBP-1. First trimester villous trophoblast cells were regulated by all these factors. IGF-II increased cell numbers 3.5-fold after 96 h in culture, and IGF-I had less effect (1.5-fold increase) (both P<0.05). IGF-II also had a greater effect on the levels of matrix metalloproteinase (MMP)-2 and MMP-9. Phosphorylated and non-phosphorylated iso-forms of IGFBP-1 added alone increased cell numbers and MMP levels (P<0.05). IGFBP-1 did not modify the effects of IGF-II on cell numbers or on MMP production. Term VCT numbers and MMP production in vitro were unaffected by IGFs (P>0.05). Cell numbers were increased only by 100 nM IGFBP-1 isoforms (P<0.05), whereas MMP levels released from term cells were optimally increased by 1–10 nM IGFBP-1. Overall, our data show that IGFs regulate only first trimester, but not term, VCT. IGFBP-1 regulates VCT from both gestations, but the effects are concentration and end-point specific. In particular, first trimester cell numbers are more affected by low levels of IGFBP-1, whereas high levels of IGFBP-1 are needed to increase MMP and the converse applies to term VCT; low levels of IGFBP-1 have more effect on MMP levels.