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B Huppertz

Publications and source records attributed to B Huppertz.

At least 19 recordsLinked to original sources
PubMed2006

Placental morphology: from molecule to mother -- a dedication to Peter Kaufmann -- a review.

Theories on the development of placental pathologies and insufficiencies are based on the assumption that the development of the placental villous trees, the invasion of extravillous trophoblast or the differentiation of the villous trophoblast is somehow dysregulated. One of the pioneers trying to answer these questions is Peter Kaufmann, who started research on the placenta nearly 40 years ago. In this review, we try to shed light on various aspects of placental development, and on how important morphology is in combination with other disciplines to elucidate the differences between a normal and a pathological placenta.

Female↗
PubMed2006

Ultrasound detection of placental insufficiency in women with 'unexplained' abnormal maternal serum screening results.

Serious placental insufficiency results in perinatal death or preterm birth from ischemic-thrombotic pathology, a process which has its origins in placental maldevelopment in the first trimester. A proportion of at-risk pregnancies may be identified from abnormalities in first or second trimester serum screening data, uterine artery Doppler waveforms or placental shape and texture at the time of the 18-20-week anatomical examination. In combination, these tests may be capable of recognizing a subset of at-risk pregnancies with 50% positive predictive values. Early recognition before fetal viability affords opportunities to direct women to regional perinatal care centres for enhanced maternal-fetal surveillance, corticosteroids to enhance fetal lung maturation, prophylactic measures to prevent pre-eclampsia and optimal decision making around the time of delivery. The creation of regional screening programs to use screening data with a placental focus is likely to be cost-effective, because existing patterns of care are utilized. More importantly, this strategy can direct women to participate in clinical research programs designed to reduce morbidity and mortality from this common group of conditions.

Biomarkers↗
PubMed2005

Aberrations of early trophoblast differentiation predispose to pregnancy failure: lessons from the anti-phospholipid syndrome.

OBJECTIVES: The epithelium of the human placenta comprises an inner cytotrophoblast (CT) which proliferates and fuses with the outer differentiated syncytiotrophoblast (ST). Turnover has been studied focussing on second and third trimester placentas but with a paucity of data describing the normal first trimester trophoblast. The aim of this study was to compare the nuclear CT:ST ratio in normal and pathological pregnancy and thus establish the relationship between cytotrophoblast and syncytiotrophoblast nuclear number during early gestation. METHODS: Archival first trimester material from placentas from healthy pregnancy and recurrent miscarriage (anti-phospholipid syndrome) was stained with H&E, cytokeratin-7 and Mib-1. The area of trophoblast as a fraction of total villous area was calculated and the number of sectioned cytotrophoblast and syncytiotrophoblast nuclei as well as the number of proliferating cytotrophoblast was evaluated. RESULTS: Normal features of trophoblast development during the first trimester (rise in trophoblast area, increase in number of syncytiotrophoblast nuclei, increase in number of proliferating cytotrophoblast, decrease in the nuclear CT:ST ratio) are absent/reversed in tissues from recurrent miscarriage (decreasing trophoblast area, constant number of syncytiotrophoblast nuclei, decreasing number of proliferating trophoblast, constant nuclear CT:ST ratio). CONCLUSIONS: Proliferation of cytotrophoblast in early gestation provides a pool of trophoblast stem cells critical for ongoing placental development. Premature cytotrophoblast differentiation in favour of syncytial fusion results in deficiencies of cytotrophoblast and rarification of villous trophoblast. Abnormal trophoblast differentiation in early gestation may be due to a premature onset of maternal perfusion of the placenta and may be a likely antecedent for conditions associated with failure of placentation such as recurrent miscarriage.

Abortion, Habitual↗
PubMed2005

Sequential steps during vasculogenesis and angiogenesis in the very early human placenta.

Development of blood vessels takes place via two subsequent processes, vasculogenesis and angiogenesis. During vasculogenesis, formation of first blood vessels is achieved by differentiation of hemangiogenic stem cells from pluripotent mesenchymal cells, while during angiogenesis new blood vessels form from already existing vessels. The combination of our data with those from the literature leads us to depict the chronological steps of cell differentiation in the mesenchymal core of placental villi during vasculogenesis and angiogenesis. This current opinion will focus on the temporal and spatial expression of VEGF and its receptors VEGFR-1 and VEGFR-2, and the angiopoietin receptors Tie-1 and Tie-2 in parallel to vascular maturation in human placental villi during very early stages of placental development. There is evidence that the interplay of a variety of growth factors secreted from different cell types during development is needed to trigger as well as maintain placental vasculogenesis and angiogenesis.

Adult↗
PubMed2005

Spatial and temporal distribution of Tie-1 and Tie-2 during very early development of the human placenta.

Vasculogenesis in the human placenta comprises differentiation and growth of newly forming blood vessels derived from hemangiogenic stem cells within the mesenchymal core of villi. In a second stage, angiogenesis leads to the expansion and remodeling of the already existing vessels. At present, relatively little is known about the regulatory mechanisms of vasculogenesis and angiogenesis during very early placentation. Using placental villous tissues from days 22 to 48 of pregnancy, we analyzed the spatial and temporal expression of Tie-1 and Tie-2 in parallel to vascular maturation in the human placenta. In immunohistochemistry both receptors, Tie-1 and Tie-2 show a cell and villous type specific expression during this early phase of placental development. Especially, cytotrophoblast and hemangiogenic cell cords in mesenchymal villi and Hofbauer cells in immature intermediate villi have the strongest immunoreactivities. Western blot analysis showed that no significant changes were detected for Tie-1 and Tie-2 as pregnancy advanced. Moreover, phospho-Tie-2 levels did not change significantly in parallel to pregnancy ages. We conclude that both receptors are involved in angiogenesis as well as vascular modulation of early vessels. Due to their spatial distribution we speculate on an additional role in regulation of villous and extravillous trophoblastic behavior.

Adult↗
PubMed2005

Bi-potential behaviour of cytotrophoblasts in first trimester chorionic villi.

Murine trophoblast stem (TS) cells express fibroblast growth factor receptor 2 (FGFR2) and are maintained in their proliferative state by fibroblast growth factor 4 (FGF4). We show in this report that in the first trimester human placenta FGFR2 expression is similarly found in a subset of villous cytotrophoblast and in proximal anchoring columns. Western analysis demonstrated declining FGFR2 protein expression as gestation advanced, suggesting a similar role for FGF in early human trophoblast proliferation. Mouse TS cell differentiation is known to occur along two distinct transcriptionally-regulated pathways; extravillous trophoblast (EVT) cells invade the uterine wall to promote maternal blood flow whilst syncytiotrophoblast lines chorionic villi in the labyrinth. Similar differentiation steps occur in the human placenta though the fate of human trophoblast stem cells is presently unknown. To investigate the mechanisms underlying human cytotrophoblast differentiation we have developed a novel cultured floating first trimester villous explant model in which denuded first trimester villi spontaneously regenerate syncytiotrophoblast following 48 h of culture. Addition of FGF4 and heparin inhibited syncytiotrophoblast regeneration in favor of forming clumps of cytotrophoblast. Proximal cells in these clumps were FGFR2 immuno-reactive and proliferative, intermediate parts expressed alpha5beta1-integrin, while the distal portion expressed HLA-G and the invasive integrin alpha1beta1 indicating differentiation to the EVT phenotype. In contrast, non-denuded villi exposed to FGF4 exhibited similar proliferation of the cytotrophoblast; however, these cells did not express any of the invasive EVT markers. We conclude that FGFR2-positive chorionic cytotrophoblasts exhibit bi-potential behaviour, being capable of forming either syncytiotrophoblast or EVT. We suggest bipotential trophoblast progenitor cells persist during first trimester human placental development.

Animals↗
PubMed2005

A comparative study of the effect of three different syncytiotrophoblast micro-particles preparations on endothelial cells.

Pre-eclampsia is a pregnancy-associated multi-system disorder of unknown etiology, characterized by damage to the maternal endothelium. The latter facet has been suggested to be mediated in part by elevated shedding of inflammatory placental syncytiotrophoblast micro-particles (STBM) into the maternal circulation. In this study, we have examined STBM prepared by three different methods: mechanical dissection, in vitro placental explant culture and perfusion of placental cotyledons. All three preparations yielded morphologically similar STBM, as confirmed by scanning electron microscopy, and all contained syncytiotrophoblast-specific proteins as determined by the presence of placental alkaline phosphatase. The functional properties of the three STBM preparations were examined on human umbilical vein endothelial cells (HUVEC), where the mechanically prepared particles were found to inhibit proliferation to the greatest extent. Furthermore, only mechanically prepared STBM lead to the detachment and apoptosis of HUVEC cells. Our study, therefore, suggests that STBM prepared from placental perfusion or in vitro explant culture are biologically different from mechanically prepared ones, and may provide a better approximation of physiologically produced placental micro-particles.

Adult↗
PubMed2005

Human placental explants in culture: approaches and assessments.

Placental explant cultures in vitro are useful for studying tissue functions including cellular uptake, production and release of secretory components, cell interactions, proliferation, growth and differentiation, gene delivery, pharmacology, toxicology, and disease processes. A variety of culture conditions are required to mimic in utero environments at different times of gestation including differing oxygen partial pressures, extracellular matrices and culture medium. Optimization of explant methods is examined for first and third trimester human placental tissue and the biological processes under investigation.

Biocompatible Materials↗
PubMed2005

Extravillous trophoblast apoptosis--a workshop report.

During normal pregnancy, extravillous trophoblast cells invade maternal uterine tissues. The interstitial trophoblast penetrates decidual tissues reaching the inner third of the myometrium. A subset of the interstitial trophoblast, the intramural/endovascular trophoblast transforms uterine spiral arteries into large-bore conduits to enable the adequate supply of nutrients and oxygen to the placenta and thus the fetus. Control of invasion is still a mystery and therefore, in this workshop report already existing concepts as well as new models are discussed. Maternal cells such as macrophages and endothelial cells have a clear impact on trophoblast invasion and apoptosis. However, the trophoblast cells need to be susceptible to undergo apoptosis. Thus, an intrinsic program within the trophoblast needs to be activated before induction from the outside can be successful. Quantification of apoptosis further clarified that apoptosis of interstitial trophoblast is not the ultimate means to lead to pathologically shallow invasion. On the other hand, apoptosis of intramural/endovascular trophoblast seems to be highly relevant for a correct transformation of spiral arteries.

Animals↗
PubMed2005

Regulation of functional steroid receptors and ligand-induced responses in telomerase-immortalized human endometrial epithelial cells.

Information on the regulation of steroid hormone receptors and their distinct functions within the human endometrial epithelium is largely unavailable. We have immortalized human primary endometrial epithelial cells (EECs) isolated from a normal proliferative phase endometrium by stably transfecting the catalytic subunit (hTERT) of the human telomerase complex and cultured these hTERT-EECs now for over 350 population doublings. Active hTERT was detected in hTERT-EECs employing the telomerase repeat amplification assay protocol. hTERT-EECs revealed a polarized, non-invasive epithelial phenotype with apical microvilli and production of a basal lamina when grown on a three-dimensional collagen-fibroblast lattice. Employing atomic force microscopy, living hTERT-EECs were shown to produce extracellular matrix (ECM) components and ECM secretion was modified by estrogen and progesterone (P4). hTERT-EECs expressed inducible and functional endogenous estrogen receptor-alpha (ER-alpha) as demonstrated by estrogen response element reporter assays and induction of P4 receptor (PR). P4 treatment down-regulated PR expression, induced MUC-1 gene activity and resulted in increased ER-beta transcriptional activity. Gene activities of cytokines and their receptors interleukin (IL)-6, leukemia inhibitory factor (LIF), IL-11 and IL-6 receptor (IL6-R), LIF receptor and gp130 relevant to implantation revealed a 17 beta-estradiol (E2)-mediated up-regulation of IL-6 and an E2- and P4-mediated up-regulation of IL6-R in hTERT-EECs. Thus, hTERT-EECs may be regarded as a novel in vitro model to investigate the role of human EECs in steroid hormone-dependent normal physiology and pathologies, including implantation failure, endometriosis and endometrial cancer.

Biomarkers↗
PubMed2004

Fetal cells and cell free fetal nucleic acids in maternal blood: new tools to study abnormal placentation?

The analysis of fetal cells, and more recently cell free fetal nucleic acids, in maternal blood has to date largely been concerned with the development of risk free methods for prenatal diagnosis. Although elevated feto-maternal cell trafficking has long been associated with preeclampsia, it has only recently been shown that this perturbation is an early event in these pregnancies, occurring well in advance of the onset of symptoms. In a separate development, analogous observations have been made concerning the levels of circulatory fetal nucleic acids in maternal plasma. Subsequent studies have shown that changes in these two parameters may also occur in other pregnancy related disorders including preterm labour, intra-uterine growth retardation, hyperemesis gravidarum or even pregnancies at high altitude. A striking finding of these examinations was that preterm labour was associated with an elevated release of cell free fetal nucleic acids but not with an increment in feto-maternal cell trafficking. This suggested that the analysis of the mechanisms regulating trans-placental cell trafficking or liberation of circulatory fetal nucleic acids may provide key insights into the fundamentally different placental lesions underlying these disorders. As such, circulatory fetal cells and nucleic acids may be viewed as new tools to study alterations in placentation.

Adult↗
PubMed2004

Endogenous retroviral syncytin: compilation of experimental research on syncytin and its possible role in normal and disturbed human placentogenesis.

Placental syncytin was first described in the year 2000 as a fusogenic glycoprotein originally derived from a human endogenous retroviral envelope gene. Although the presence of stable integrated retroviral elements within the human genome has been known for many years, their biological significance is still obscure and has usually been designated as irrelevant or even harmful. Syncytin, however, demonstrates tissue-specific expression and distinctive receptor interaction during trophoblast cell differentiation and syncytium formation. These findings indicate an involvement of syncytin in the development of the human placenta. Disturbances in placental architecture leading to severe placental dysfunction, such as pre-eclampsia, may therefore be discussed as a consequence of an altered syncytin system. We evaluate the hypothesis that syncytin is essential for human placenta formation and may also have played an important role in human placental evolution.

Amino Acid Transport System ASC↗
PubMed2004

Sequential expression of VEGF and its receptors in human placental villi during very early pregnancy: differences between placental vasculogenesis and angiogenesis.

Vascularization within the human placenta is the result of the de novo formation of vessels derived from pluripotent precursor cells in the mesenchymal core of the villi. Vascularization of placental villi starts at around day 21 post conception (p.c.) with a four somite embryo. At this stage progenitors of haemangiogenic cells differentiate to form first vessels. These progenitor cells are thought to be directly derived from mesenchymal cells rather than originating from fetal blood cells. We investigated the relation between differentiation of stromal cells towards endothelial cells and vascular structures and the expression pattern of the respective growth factors. Using transmission electron microscopy and immunohistochemistry (for VEGF, Flt-1, Flk-1, CD14, CD34, and CD68) the development of placental vasculogenesis during very early stages of pregnancy (days 22-48 p.c.) was studied. We found that VEGF is strongly expressed in villous cytotrophoblast cells and subsequently in Hofbauer cells while its receptors Flt-1 and Flk-1 are found on vasculogenic and angiogenic precursor cells. The developmental expression and secretion of VEGF suggests its involvement in recruitment, maintenance and formation of first angiogenic cells and vessels. Interactions between VEGF and Flk-1 and Flt-1 may regulate placental vasculogenesis and angiogenesis in a paracrine and autocrine manner. The sequential expression of growth factors in different cell types may point to the fact that placental vasculogenesis and angiogenesis are clearly distinct events.

Antigens, CD↗
PubMed2004

Complex patterns of GCM1 mRNA and protein in villous and extravillous trophoblast cells of the human placenta.

The Gcm1 gene encodes a transcription factor that is essential for both syncytiotrophoblast differentiation and formation of chorionic villi in mice. Its early expression is very unusual in that it defines a subset of trophoblast cells in the chorion, a layer that otherwise contains trophoblast stem cells. While Gcm1 mRNA expression initiates independently within the chorion, the subsequent maintenance of mRNA expression as well as the onset of protein accumulation is dependent on contact with allantoic mesoderm. Previous studies have shown that human GCM1 mRNA and protein are detectable in the placenta, but their patterns have not been compared nor precisely localized. We, therefore, conducted the present study to determine if the human mRNA and protein are subject to the same complexities of regulation as the mouse. In situ hybridization studies showed that the GCM1 mRNA was expressed in villous cytotrophoblast cells, but only a subset and never within cells immediately at the base of columns. Interestingly, the mRNA was detected throughout the cytotrophoblast columns. GCM1 protein expression studies demonstrated that the transcription factor was present mainly within the nuclei of a subset of cytotrophoblast cells, consistent with its role as a transcription factor. Feint cytoplasmic staining of the transcription factor was found in the syncytiotrophoblast but not in aggregated syncytial nuclei. Nuclear immuno-reactivity for the GCM1 protein was detected in occasional nuclei in the distal part of the column. Therefore, GCM1 expression is regulated both at the transcriptional and translational level. Overall, these studies show that the general features of GCM1 mRNA and protein expression in the human placenta are conserved with the mouse. They also highlight the fact that villous cytotrophoblast cells are extremely heterogeneous with respect to GCM1 expression, a factor that should be considered when using isolated cytotrophoblast cells for culture studies.

Blotting, Northern↗
PubMed2004

Syncytial fusion of human trophoblast depends on caspase 8.

Differentiation of human placental villous trophoblast includes syncytial fusion of cytotrophoblast forming syncytiotrophoblast. Early stages of the apoptosis cascade were described to be involved in this differentiation process. We investigated the role of the initiator caspase 8 in syncytial fusion in vitro, cultivating placental villous explants with or without caspase 8 antisense oligonucleotides or peptide inhibitors for up to 120 h. Trophoblast fusion and differentiation were assessed by confocal microscopy, immunohistochemistry and Western blot analysis. Culture with caspase 8 antisense oligonucleotides or peptide inhibitors reduced the fusion of cytotrophoblast with the syncytiotrophoblast, and resulted in multilayered cytotrophoblast. Caspase 8 expression was suppressed by antisense oligonucleotides and caspase 8 activities were reduced by peptide inhibitors. The organic anion-transporter hOAT-4 normally expressed in the cytotrophoblast and transferred into the syncytiotrophoblast by syncytial fusion was retained in the cytotrophoblast due to lack of fusion. We conclude that expression and activity of caspase 8 is a prerequisite for differentiation and syncytial fusion of cytotrophoblast cells.

Apoptosis↗
PubMed2003

The 'reference trap' revisited: examples of the dangers in using ratios to describe fetoplacental angiogenesis and trophoblast turnover.

Examples of the use of relative or ratio data are to be found throughout biomedical sciences and include such variables as stereological component densities per cell volume (morphology), transport rates per tissue volume or membrane surface (physiology), gold labelling frequencies (immunocytochemistry) and amounts of DNA relative to protein (biochemistry). This report emphasizes the potential pifalls associated with drawing biological conclusions and interpretations from relative data when there has been no attempt to monitor the absolute size of the reference space. This is know as the 'reference trap'. The dangers to interpretation inherent in confining results to such data are illustrated using the sorts of data found in current placental studies on fetoplacental angiogenesis and villous trophoblast turnover but are pertinent to many other areas. Where it is possible to do so, these dangers can be avoided by the simple expedient of estimating the size of the pertinent reference space and using this to calculate absolute values. Sometimes (e.g. when relying on biopsy samples), the size of the reference cannot be determined. In such cases, ratio data must be interpreted with due caution.

Adult↗
PubMed2003

Pre-eclampsia and maternal anaemia display reduced apoptosis and opposite invasive phenotypes of extravillous trophoblast.

During pregnancy extravillous trophoblast invades maternal uterine tissues and remodels spiral arteries. Maternal anaemia and early onset pre-eclampsia are associated with perturbed trophoblast biology. We systematically compared numerical density, invasive depth and apoptosis rates of extravillous trophoblast in uterine tissues taken from hysterectomies following Caesarean section after normal pregnancies (n=4) or pregnancies complicated by pre-eclampsia (n=5) or anaemia (n=6). Full thickness sections of the placental bed were studied by immunohistochemistry using anti-active caspase 3, anti-cytokeratin 7, anti-lamin B, M30, Mib-1, anti-PARP, and by the TUNEL assay. In normal pregnancy extravillous trophoblast invaded 2.04+/-0.19 mm (mean+/-SEM ) from the endometrial-myometrial border into the myometrium; in pre-eclampsia 0.67+/-0.14 mm (P< 0.01), and in anaemia 3.84+/-0.21 mm (P< 0.001). The endometrial trophoblast density in normal pregnancy was 2.44+/-0.37 cells per 60,000 microm(3), in pre-eclampsia was 1.04+/-0.15 (P< 0.01), and in anaemia was 3.10+/-0.32. The rate of apoptotic extravillous trophoblast (M30-positive) in the endometrium in normal pregnancy was 7.17+/-1.46 per cent, in pre-eclampsia 4.4+/-0.71, and in anaemia 2.1+/-0.42 (P< 0.01). Maternal anaemia leads to general tissue hypoxia throughout gestation. Increased invasive depth could be explained by hypoxia-stimulated mitosis and decreased apoptosis of extravillous trophoblast. Reduced trophoblast invasion in pre-eclampsia cannot be explained by higher rates of apoptosis.

Adult↗