Human trophoblast-extracellular matrix (ECM) interactions in vitro: ECM thickness modulates morphology and proteolytic activity.

Abstract

Trophoblast invasion of the uterine extracellular matrix, a critical process for human implantation and uteroplacental vascular development, is a striking example of controlled invasiveness. To examine cellular behavior relevant to this process, human trophoblasts were cultured on (a) Millicell filters prelayered with Matrigel and (it) coverslips precoated with a gentle slope of Matrigel (Matribeach). Histologic sections of the Millicell system demonstrated significant invasion. However, on Matribeach the cells exhibited markedly different characteristics depending on the thickness of the Matrigel. On zone 1 (1-4 ,um thick), flat aggregates and syncytia were seen. In contrast, cells on zone 2 (4-14 pzm) formed rounded aggregates with intercellular processes. In this zone, prominent degradation of pericellular Matrigel proteins was assessed by both light microscopy and scanning electron microscopy. Treatment with 8-bromo-cAMP inhibited this proteolytic process. On zone 3 (14-60 pmm), unicellular trophoblasts or small aggregates caused minimal matrix degradation. JEG-3 human choriocarcinoma cells exhibited similar morphologic and degradative properties on Matribeach, but zone 2 proteolysis was not affected by 8-bromo-cAMP. Our results suggest that extracellular matrix thickness has profound effects on cellular morphology and proteolytic activity. Furthermore, while both normal and malignant human trophoblasts can degrade extracellular matrix proteins, only normal trophoblast extracellular matrix degradation is inhibited by 8-bromo-cAMP.During human gestation, trophoblasts invade the uterine extracellular matrix (ECM), remodel the maternal vasculature, and line vascular channels in the placental bed (1). The biological repertoire necessary for these unique trophoblast-ECM interactions is unknown. Although trophoblast behavior has been compared to that of tumor cells with invasive activity, trophoblasts generally exhibit tightly regulated growth and invasion in vivo.Certain features of cytotrophoblast differentiation in vivo can be recapitulated in vitro when human cytotrophoblasts are purified and cultured from term placentae (2). Once isolated from the placental villi, these mononuclear cells undergo morphologic as well as biochemical differentiation in vitro. Cytotrophoblasts form multinucleated syncytia and carry out de novo secretion of human chorionic gonadotropin (hCG), human placental lactogen, and progesterone (2-4). During this differentiation process cytotrophoblasts also attach to ECM proteins (5) and synthesize fibronectin (6) and laminin (7). Urokinase-type plasminogen activator (u-PA) is secreted by cytotrophoblasts in culture (8), as are the plasminogen activator inhibitor (PAI) types 1 and 2 (9). cAMP has profound effects on cytotrophoblasts in culture by affecting their intracellular morphology and synthesis of hCG, fibronectin, and u-PA (4,6,8).Since cytotrophoblasts in culture are capable of exhibiting multiple facets of the trophoblast differentiation process, we wished to determine whet...

Trophoblast Invasion and Placentation: Molecular Mechanisms and Regulation

“…Human CTBs are able to invade amniotic membranes [37] and Matrigel invitro [38][39][40], and to digest ECM [5]. This behavior is clearly related to secreted metalloproteinases, as TIMP expression inhibits their invasiveness [37].…”

“…Preeclampsia is characterized by a decreased expression of HGF by the stroma of the villi [78]. Protein kinase C activators such as phorbol esters increase in vitro trophoblast invasion [38] and secretion of MMP-9 [79]. The activity of MMP-9 is upregulated by leptin and IL-1α [73,80], and it is known that IL-1 concentrations in embryo culture medium are correlated with success of in vitro fertilization procedures [81].…”

Kisspeptin-10, a KiSS-1/metastin-derived decapeptide, is a physiological invasion inhibitor of primary human trophoblasts

“…As a result, the embryo will be anchored in the maternal uterus and uteroplacental arteries will be invaded, leading to the dilation of the vessel lumina, which is necessary to enhance uterine and intervillous blood flow in pregnancy. There are striking similarities between invasive cytotrophoblasts and invasive cancer cells (Kliman and Feinberg, 1990;Murray and Lessey, 1999;Bischof and Campana, 2000;Bilban et al, 2000;Murray and Lessey, 1999;McMaster et al, 1998). However, in contrast to tumor invasion, interactions between trophoblasts and uterine cells are closely regulated both temporally and spatially by mechanisms that are largely unknown.…”

Tissue-specific Expression of the Relaxed Conformation of Plasminogen Activator Inhibitor-2 and Low-density Lipoprotein Receptor-related Protein in Human Term Gestational Tissues

“…Human term gestational tissues express all components of the PA cascade and undergo extensive ECM remodeling at the time of labor and delivery (Feinberg et al 1989;Granstrom et al 1989Granstrom et al ,1991Granstrom et al ,1992Kliman and Feinberg 1990;Hofmann et al 1994;Kliman 1994). It has been suggested that localized degenerative changes in the amnion and chorion may be sufficient to reduce tensile strength and hence mediate fetal membrane rupture at term (Vadillo-Ortega et al 1995).…”