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G St J Whitley

Publications and source records attributed to G St J Whitley.

6 recordsLinked to original sources
PubMed2005

Three-dimensional growth of extravillous cytotrophoblasts promotes differentiation and invasion.

Human trophoblast research relies on a combination of in vitro models, including isolated primary cultures, explant cultures, and trophoblast cell lines. In the present study, we have utilized the rotating wall vessel (RWV) bioreactor to generate a three-dimensional (3-D) model of human placentation for the study of cytotrophoblast (CTB) invasion. The RWV supported the growth of the human CTB cell line SGHPL-4 and allowed for the formation of complex, multilayered 3-D aggregates that were morphologically, phenotypically, and functionally distinct from SGHPL-4 monolayers. The cells cultured three-dimensionally differentiated into an aggressively invasive cell population characterized by the upregulation of matrix metalloproteinase-2 (MMP-2), MMP-3, MMP-9 and urokinase-type plasminogen activator (uPA) secretion and activation. Microarray analysis of the 3-D and 2-D cultured cells revealed increased expression in the 3-D cells of various genes that are known mediators of invasion, including MT1-MMP, PECAM-1 and L-selectin, as well as genes not previously associated with CTB differentiation such as MMP-13 and MT5-MMP. These results were verified by quantitative real-time PCR. These findings suggest that when cultured in 3-D, SGHPL-4 cells closely mimic differentiating in utero CTBs, providing a novel approach for the in vitro study of the molecular mechanisms that regulate CTB differentiation and invasion.

Bioreactors↗
PubMed2002

Dimethylarginine dimethylaminohydrolase I enhances tumour growth and angiogenesis.

Angiogenesis is a prerequisite for tumour progression and is highly regulated by growth factors and cytokines a number of which also stimulate the production of nitric oxide. Asymmetric dimethylarginine is an endogenous inhibitor of nitric oxide synthesis. Asymmetric dimethylarginine is metabolised by dimethylarginine dimethylaminohydrolase. To study the effect of dimethylarginine dimethylaminohydrolase on tumour growth and vascular development, the rat C6 glioma cell line was manipulated to overexpress the rat gene for dimethylarginine dimethylaminohydrolase I. Enhanced expression of dimethylarginine dimethylaminohydrolase I increased nitric oxide synthesis (as indicated by a two-fold increase in the production of cGMP), expression and secretion of vascular endothelial cell growth factor, and induced angiogenesis in vitro. Tumours derived from these cells grew more rapidly in vivo than cells with normal dimethylarginine dimethylaminohydrolase I expression. Immunohistochemical and magnetic resonance imaging measurements were consistent with increased tumour vascular development. Furthermore, dimethylarginine dimethylaminohydrolase activity was detected in a series of human tumours. This data demonstrates that dimethylarginine dimethylaminohydrolase plays a pivotal role in tumour growth and the development of the tumour vasculature by regulating the concentration of nitric oxide and altering vascular endothelial cell growth factor production.

Amidohydrolases↗
PubMed2002

Transforming growth factor-beta1 regulates hepatocyte growth factor-induced trophoblast motility and invasion.

During placental development extravillous trophoblasts invade the uterine wall in a tightly regulated manner dependent on both pro- and anti-invasive molecules. We have shown using the extravillous trophoblast cell line, SGHPL-4, that both cellular invasion and motility are stimulated by hepatocyte growth factor (HGF). It has previously been demonstrated that transforming growth factor=beta1 (TGF-beta1), produced by the decidua, inhibits extravillous trophoblast proliferation and invasion. It was the aim of this study to determine whether TGF-beta1 could modulate HGF-induced motility and invasion and, if so, examine the mechanism involved. TGF-beta1 significantly inhibited the growth of SGHPL-4 cells stimulated with 10 per cent serum. HGF-stimulated trophoblast cell invasion and motility were significantly inhibited by TGF-beta1. Neither HGF nor TGF-beta1 had an effect on SGHPL-4 cell growth under the conditions used for the invasion and motility experiments (0.5 per cent serum). Previous studies suggest that both HGF-stimulated trophoblast invasion and motility may be regulated by the production of nitric oxide. TGF-beta1 was found to significantly decrease HGF-induced iNOS expression therefore suggesting a novel mechanism by which TGF-beta1 could regulate motility and invasion.

Blotting, Western↗
PubMedDate not supplied

Human cytomegalovirus-induced inhibition of cytotrophoblast invasion in a first trimester extravillous cytotrophoblast cell line.

Human cytomegalovirus (HCMV) is the leading cause of congenital viral infection in the United States and intrauterine transmission of HCMV occurs in approximately 40% of pregnant women with primary HCMV infection. Although HCMV infection during pregnancy clearly may be detrimental to fetal development, its consequences on placentation remain largely unexplored. In this study, the effects of HCMV infection on cytotrophoblast (CTB) invasion were investigated utilizing the first trimester extravillous CTB cell line SGHPL-4. HCMV infection significantly inhibited SGHPL-4 proliferation, epidermal growth factor (EGF)- and hepatocyte growth factor (HGF)-induced migration and invasion, as well as the secretion of matrix metalloproteinase (MMP)-2 and MMP-9. Both HCMV and EGF activated the EGF receptor (EGFR), inducing receptor tyrosine phosphorylation at specific residues. Of interest, EGFR was differentially activated by HCMV, and viral gene transcription was not required for the observed inhibitory effect on CTB invasiveness. These findings demonstrate that HCMV infection impairs CTB differentiation along the invasive pathway and that the differential regulation of EGFR by HCMV may contribute to impaired CTB function. Elucidating the mechanisms by which HCMV impairs placentation may be key in understanding fetal and maternal pathologies associated with intrauterine HCMV infection.

Cell Line↗
PubMedDate not supplied

Trophoblast invasion of spiral arteries: a novel in vitro model.

Extravillous trophoblasts invade the uterine wall (interstitial invasion) and the spiral arteries (endovascular invasion), replacing the cells of the vessel wall and creating a high-flow low-resistance vessel. We have developed a novel model to allow the interactions between the invading trophoblast cells and the cells of the spiral artery to be directly examined. Unmodified (non-placental bed) spiral arteries were obtained from uterine biopsies at caesarean section. Fluorescently labelled trophoblasts were seeded on top of artery segments embedded in fibrin gels (to study interstitial invasion) or perfused into the lumen of arteries mounted on a pressure myograph (to study endovascular invasion). Trophoblasts were incubated with the vessels for 3-5 days prior to cryo-sectioning. Both interstitial and endovascular interactions/invasion could clearly be detected and a comparison of the extravillous trophoblast cell line, SGHPL-4 and primary first trimester cytotrophoblasts showed both to be invasive in this model. This novel method will prove useful in an area where in vitro studies have been hampered by the lack of suitable models directly examining cellular interactions during invasion.

Adult↗