392 Placenta (1991), Vol. 12

The localization of aminopeptidase A (angiotensinase A) in cells of the human and rat placental barrier and alterations of enzyme activities by hypertensive disorders may point to a local modulation of the renin-angiotensin system. [Supported by the German Research Foundation (Sfb 174).]

FUNCTION OF TGF/? IN TROPHOBLAST DIFFERENTIATION C. H. Graham, D. Belliveau & P. K. Lala (Department of Anatomy, University of Western Ontario, London, Canada N6A Xl)

We examined the role of TGFB on in vitro proliferation and differentiation of human trophoblast cells. First trimester trophoblast cultures were established using a method developed in this laboratory (Yagel et al, 1989,Am. 3’. Obstet. Gynecol., 160,938-945). Term trophoblast cultures were prepared after Kliman et al (1986, Endotinologv, 118,1567-1582). Cells were characterized morphologically, immunohistochemically, and by their ability to produce hormones. Exposure to TGFbr (10 ng/ml) inhibited first trimester trophoblast proliferation (P < 0.01) measured on day 6 and increased syncytia formation in both first trimester (P < 0.003) and term (P < 0.0003) trophoblast. Addition of exogenous TGF/$ increased the number of nuclei in syncytia in both types of cultures 3 days after plating. Addition of neutralizing anti-TGF/? antibody caused an increased “‘1-dUR uptake by first trimester trophoblast (P < 0.00024) and reduced syncytium formation (P < 0.03) and the number of nuclei in syncytia, indicating the presence of endogenous TGFP activity. Northern analysis revealed a reduction in gap junction connexin32 mRNA in first trimester cultures exposed to anti-TGF/3 antibody, indicating that endogenous TGFP induces this message. Our studies suggest that TGF/3 exercises major effects in situ on trophoblast cell physiology: (1) it down-regulates first trimester trophoblast proliferation and invasiveness; (2) it promotes trophoblast differentiation by induction of gap junctions (first trimester) and syncytium formation (first trimester and term trophoblast). (Supported by the MRC and the NC1 Canada.)

MOLECULAR MECHANISMS CONTROLLING TROPHOBLAST INVASION IN SITU C. H. Graham & P. K. Lala (Department of Anatomy, University of Western Ontario, London, Ontario, Canada N6A 5Cl)

We have previously shown that first trimester human trophoblast cells share in vitro invasive properties with malignant cells. In this study we show that the in situ control of trophoblast invasion is provided by the uterine microenvironment. Trophoblast cells were labeled with 1251-deoxyuridine and examined for their ability to invade an epithelium-free human amniotic membrane in vitro under various conditions. The degree of invasion was deter- mined as the percentage of the radioactivity retained within the membrane. Conditioned media from first trimester human decidual cells (DCM) suppressed invasion of trophoblast cells in the amnion invasion assay. This suppression was prevented by addition of neutral- izing anti-TGF/3 antibody or neutralizing antibody to Tissue Inhibitor of Metalloproteinases (TIMP)-1 to the DCM, and mimicked by TGFP1. These antibodies also augmented