Expression of contractile proteins α-actin and myosin of smooth muscle cells and of type IV collagen in human placenta at placental insufficiency in III trimester of pregnancy

Changes of expression of contractile proteins (smooth muscle cell α-actin and myosin) and of type IV collagen in villous stroma of human placenta were studied at the diagnosed placental insufficiency (PI) in III trimester of pregnancy. The study revealed pronounced disturbances of expression of contractile proteins and type IV collagen at PI. It is shown that in perivascular sheaths of vessels of stem and intermediate villi there is present a much greater amount of cells expressing smooth muscle actin and myosin. These cells are arranged by the denser concentric layers and more compactly than in norm and fill the intervascular space inside the villi. The width of perivascular sheaths of vessels is higher, while vascular lumens are lower than in norm. In terminal villi the capillary walls are thickened and the number of pericytes immunopositive against the smooth muscle cell α-actin and myosin as well as type IV collagen is increased. The change of synthesis of the cytoskeletal contractile proteins and type IV collagen is shown to lead to structural disturbances of villi of different types and of perivascular areas and vessels, which doubtlessly indicates their participation in pathogenesis of placental dysfunction and of disturbance of placental hemodynamics.     

Changes in placental dipeptidyl peptidase IV in preeclampsia with intrauterine growth restriction.

The purpose of this study was to examine alterations in placental expression of dipeptidyl peptidase IV (DPPIV). The localization of DPPIV was compared in control and preeclamptic placentas. Enzyme activity, mRNA, and protein expression were also measured. In term placentas, DPPIV was expressed preferentially in the fetal vascular endothelial cells within stem villi and only weakly in the villous stromal cells. DPPIV activity in control placentas showed no remarkable changes throughout gestation. Levels of activity in samples from normotensive control cases and women having preeclampsia with or without intrauterine growth restriction were 11.8 +/- 2.1, 13.4 +/- 1.1, and 15.3 +/- 0.62 pmol pNA/min/mg protein, respectively. The preeclamptic placentas with intrauterine growth restriction thus showed significantly higher levels of activity than the controls (p < 0.05). We propose that placental DPPIV influences fetal metabolism via the degradation of fetoplacental circulating bioactive peptides, including incretins, resulting in the regulation of fetal growth.     

细胞色素P450scc在人早期胎盘中的表达（简报）

人妊娠期间,胎盘合成大量的类固醇激素,与妊娠的启动、维持、分娩以及胎儿的发育均存在密切的关系。阐明胎盘类固醇激素特别是孕酮合成与分泌的调节机制对于寻找理想的生育调控技术和生殖保健方法具有重要的意义。因此,胎盘类固醇激素合成与分泌的调节向来是生殖生物学与妇产科学领域所关注的焦点问题之一,     

Heterogeneous histochemical reaction pattern of the lectin Bandeiraea (Griffonia) simplicifolia with blood vessels of human full-term placenta

Bandeiraea simplicifolia lectin (BS-I) stains vascular endothelium in various species. In humans, less than 10% of the specimens studied exhibit a reaction with BS-I. In the present histochemical study, the reactivity of BS-I with placental blood vessels and its correlation with the blood group from mother and newborn child was investigated. Acetone-fixed cryosections of representative tissue segments of human full-term placenta and umbilical cord were stained with BS-I. The staining pattern of tissues from patients with different blood groups was identical, although the reaction of BS-I in the placenta was heterogeneous. BS-I did not react with the umbilical cord. Vascular smooth muscle cells at the insertion site of the umbilical cord into the chorionic plate, and endothelium deeper in the chorionic plate, became progressively stained. The endothelial cells and tunica muscularis of smaller arteries and veins in stem villi lost their reactivity in parallel with decreasing vessel size. Arterioles and venules reacted heterogeneously. Capillaries, trophoblastic basement membranes, especially epithelial plates, and sometimes the syncytiotrophoblast were labelled in several terminal villi. The data indicate that 1) the placenta binds BS-I to fetal endothelium independent of the blood group, 2) cell-surface antigens on placental endothelial cells are expressed heterogeneously and 3) cell-surface glycans are constituted in an organ-specific manner on human endothelial cells.     

细胞色素P450scc在人早期胎盘中的表达(简报)

人妊娠期间,胎盘合成大量的类固醇激素,与妊娠的启动、维持、分娩以及胎儿的发育均存在密切的关系。阐明胎盘类固醇激素特别是孕酮合成与分泌的调节机制对于寻找理想的生育调控技术和生殖保健方法具有重要的意义。因此,胎盘类固醇激素合成与分泌的调节向来是生殖生物学与妇产科学领域所关注的焦点问题之一,并为此开展了大量的研究,但迄今仍不清楚,其主要原因之一是     

Involvement of calcitonin gene-related peptide in control of human fetoplacental vascular tone

Calcitonin gene-related peptide (CGRP), one of the most potent endogenous vasodilators known, has been implicated in vascular adaptations and placental functions during pregnancy. The present study was designed to examine the existence of CGRP-A receptor components, the calcitonin receptor-like receptor (CRLR) and receptor activity-modifying protein 1 (RAMP1), in the human placenta and the vasoactivity of CGRP in the fetoplacental circulation. Immunofluorescent staining of the human placenta in term labor using polyclonal anti-CRLR and RAMP1 antibodies revealed that labeling specifically concentrated in the vascular endothelium and the underlying smooth muscle cells in the umbilical artery/vein, chorionic artery/vein, and stem villous vessels as well as in the trophoblast layer of the placental villi. In vitro isometric force measurement showed that CGRP dose dependently relaxes the umbilical artery/vein, chorionic artery/vein, and stem villous vessels. Furthermore, CGRP-induced relaxation of placental vessels are inhibited by a CGRP receptor antagonist (CGRP8-37), ATP-sensitive potassium (KATP) channel blocker (glybenclamide), and cAMP-dependent protein kinase A inhibitor (Rp-cAMPS) and partially inhibited by a nitric oxide inhibitor (Nomega-nitro-l-arginine methyl ester). We propose that CGRP may play a role in the control of human fetoplacental vascular tone, and the vascular dilations in response to CGRP may involve activation of KATP channels, cAMP, and a nitric oxide pathway.     

Focus: The Science of Stress: Mesenchymal Stem/Stromal Cells and Their Role in Oxidative Stress Associated with Preeclampsia

Preeclampsia (PE) is a serious medically important disorder of human pregnancy, which features de novo pregnancy-induced hypertension and proteinuria. The severe form of PE can progress to eclampsia, a convulsive, life-threatening condition. When placental growth and perfusion are abnormal, the placenta experiences oxidative stress and subsequently secretes abnormal amounts of certain pro-angiogenic factors (eg, PlGF) as well as anti-angiogenic factors (eg, sFlt-1) that enter the maternal circulation. The net effect is damage to the maternal vascular endothelium, which subsequently manifests as the clinical features of PE. Other than delivery of the fetus and placenta, curative treatments for PE have not yet been forthcoming, which reflects the complexity of the clinical syndrome. A major source of reactive oxygen species that contributes to the widespread maternal vascular endothelium damage is the PE-affected decidua. The role of decidua-derived mesenchymal stem/stromal cells (MSC) in normotensive and pathological placenta development is poorly understood. The ability to respond to an environment of oxidative damage is a “universal property” of MSC but the biological mechanisms that MSC employ in response to oxidative stress are compromised in PE. In this review, we discuss how MSC respond to oxidative stress in normotensive and pathological conditions. We also consider the possibility of manipulating the oxidative stress response of abnormal MSC as a therapeutic strategy to treat preeclampsia.     

Integrin-linked kinase (ILK) is highly expressed in first trimester human chorionic villi and regulates migration of a human cytotrophoblast-derived cell line

The placenta represents a critically important fetal-maternal interaction. Trophoblast migration and invasion into the uterine wall is a precisely controlled process and aberrations in these processes are implicated in diseases such as preeclampsia. Integrin-linked kinase (ILK) is a multifunctional, cytoplasmic, serine/threonine kinase that has been implicated in regulating processes such as cell proliferation, survival, migration, and invasion; yet the temporal and spatial pattern of expression of ILK in human chorionic villi and its role in early human placental development are completely unknown. We hypothesized that ILK would be expressed in trophoblast subtypes of human chorionic villi during early placental development and that it would regulate trophoblast migration. Immunoblot analysis revealed that ILK protein was highly detectable in placental tissue samples throughout gestation. In floating branches of chorionic villi, from 6 to 15 wk of gestation immunofluorescence analysis of ILK expression in placental tissue sections demonstrated that ILK was highly detectable in the cytoplasm and membranes of villous cytotrophoblast cells and in stromal mesenchyme, whereas it was barely detectable in the syncytiotrophoblast layer. In anchoring branches of villi, ILK was highly localized to plasma membranes of extravillous trophoblast cells. Transient expression of dominant negative E359K-ILK in the villous explant-derived trophoblast cell line HTR8-SVneo dramatically reduced migration into wounds compared to cells expressing wild-type ILK or empty vector. Therefore, our work has demonstrated that ILK is highly expressed in trophoblast subtypes of human chorionic villi during the first trimester of pregnancy and is a likely mediator of trophoblast migration during this period of development.     

补肾益气活血方对胎儿宫内生长迟缓胎盘组织一氧化氮合酶活性的影响

为了探讨补肾益气活血方对胎儿宫内生长迟缓（ＩＵＧＲ）胎盘组织一氧化氮（ＮＯ）生成的影响,本文对正常孕妇、ＩＵＧＲ患者及补肾益气活血中药治疗后患者各１２例,采用ＮＡＤＰＨ黄递酶法研究了一氧化氮合酶（ＮＯＳ）在胎盘组织的分布,应用化学发光法测定胎盘组织ＮＯＳ活性。结果表明：正常孕妇胎盘绒毛合体滋养层细胞ＮＯＳ呈强阳性反应,绒毛干血管壁呈阳性反应,终末绒毛毛细血管壁呈阴性反应;ＩＵＧＲ患者绒毛合体滋养层细胞和绒毛干血管壁ＮＯＳ染色明显变浅,而终末绒毛毛细血管壁呈阳性反应;中药治疗后合体滋养层细胞和绒毛干血管壁ＮＯＳ染色明显加深。ＮＯＳ活性测定中药组较ＩＵＧＲ未治疗组显著增高,与正常孕妇相比其差异无显著性。结果提示：ＮＯ参与ＩＵＧＲ的病理生理过程,补肾益气活血方通过增强ＮＯＳ活性促进胎盘组织ＮＯ的产生     

Immunohistochemical expression of von Willebrand factor in the preeclamptic placenta

Preeclampsia is a high-prevalence systemic pregnancy disorder associated with maternal and foetal mortality. Its pathogenesis is unknown, but it is thought that oxidative stress and endothelial dysfunction may play a fundamental role. Von Willebrand factor (vWF), a marker of endothelial cell injury, can be found in different cells and zones of the placenta. To determine the differential immunoexpression of vWF at different tissue types of preeclamptic placenta and endothelial dysfunction markers at maternal serum of preeclamptic pregnancies. A case–control study was performed on a population of pregnant women with preeclampsia (n = 14), and normal pregnancies (n = 8). Placental and blood plasma samples were withdrawn at delivery. Immunohistochemical vWF expression in the placental tissue was determined. Endothelial dysfunction was assessed through plasminogen activator inhibitor (PAI) 1 and 2 ratio and vWF concentration in maternal plasma. P values less than 0.05 were considered statistically significant. Preeclamptic women showed increased plasma PAI-1/PAI-2 ratio (P < 0.05). There was diminished placental vWF expression in syncytiotrophoblast and increased in the intervillous space of preeclamptic placentas (P < 0.05). No significant differences in vWF expression were found in the villous endothelium and stroma, but it was significantly higher in maternal plasma (P < 0.05). In preeclampsia occurs endothelial damage and placental cell injury. Cell damage in syncytiotrophoblast that occurs in preeclampsia could liberate vWF from syncytiotrophoblast to the placental intervillous space, and this may have pathogenic implications.     

Vascular endothelial expression of indoleamine 2,3-dioxygenase 1 forms a positive gradient towards the feto-maternal interface

We describe the distribution of indoleamine 2,3-dioxygenase 1 (IDO1) in vascular endothelium of human first-trimester and term placenta. Expression of IDO1 protein on the fetal side of the interface extended from almost exclusively sub-trophoblastic capillaries in first-trimester placenta to a nearly general presence on villous vascular endothelia at term, including also most bigger vessels such as villous arteries and veins of stem villi and vessels of the chorionic plate. Umbilical cord vessels were generally negative for IDO1 protein. In the fetal part of the placenta positivity for IDO1 was restricted to vascular endothelium, which did not co-express HLA-DR. This finding paralleled detectability of IDO1 mRNA in first trimester and term tissue and a high increase in the kynurenine to tryptophan ratio in chorionic villous tissue from first trimester to term placenta. Endothelial cells isolated from the chorionic plate of term placenta expressed IDO1 mRNA in contrast to endothelial cells originating from human umbilical vein, iliac vein or aorta. In first trimester decidua we found endothelium of arteries rather than veins expressing IDO1, which was complementory to expression of HLA-DR. An estimation of IDO activity on the basis of the ratio of kynurenine and tryptophan in blood taken from vessels of the chorionic plate of term placenta indicated far higher values than those found in the peripheral blood of adults. Thus, a gradient of vascular endothelial IDO1 expression is present at both sides of the feto-maternal interface.     

Structural changes in human placenta and its vascular bed in syndrome of placental failure

Study of born placentas with chronic functional failure established in the III pregnancy trimester has revealed several characteristic structural alterations of placental villi and of its vascular bed elements. There has been shown a decrease of the number of terminal villi and an increase of their sizes (approximately 3 times) as compared with norm, a change of transformation of cytotrophoblast into syncytiotrophoblast, thickening of vascular endothelium, a decrease of the number of capillaries-sinusoids, and a decrease of the number of syncytiocapillary membranes, which leads to deterioration of conditions of the maternal-fetal diffuse exchange. It has been established that in placental failure, expression of the vascular endothelial growth factor (VEGF) by cytotrophoblast cells, syncytiotrophoblast, and Kashchenko-Hoffbauer cells is enhanced as compared with norm, which can be considered an adaptive reaction to a decrease of intensity of placental blood circulation.     

Elastic fibres are an essential component of human placental stem villous stroma and an integrated part of the perivascular contractile sheath

The stroma of human placental stem villi is believed to consist only of reticular and collagen fibres. In the present study we were able to show for the first time by light (orcein staining) and electron microscopy large amounts of elastic fibres in the stem villous stroma. Electron microscopically, homogeneous elastin was found alone or in association with microfibrils. In addition, microfibrils were observed forming long bands. These three structures, generally known to form elastic connective tissue, were seen in close connection with placental extravascular smooth muscle cells, which belong to the perivascular contractile sheath (PVCS) of stem villi. Elastin was associated with these smooth muscle cells and connected to collagen fibres via microfibrils. Collagen fibres were additionally interconnected by spike-like structures. Extravascular smooth muscle cells revealed numerous adhesion plaques which occupied conspicuously long cytoplasmic faces of the plasma membrane. In cryostat sections, immunoreactivity of talin, an attachment protein of adhesion plaques linking intracellular α-actin filaments with extracellular fibronectin, was detected in extravascular and vascular (media) smooth muscle cells. The arrangement of placental extravascular smooth muscle cells, elastic and collagen fibres suggests a functional myofibroelastic unit within the PVCS, which surrounds the large foetal blood vessels possibly contributing to elasticity and supporting tensile and/or contracting forces within the stem villi. Received: 2 May 1995 / Accepted: 7 August 1995     

Insulin receptors in syncytitrophoblast and fetal endothelium of human placenta. Immunohistochemical evidence for developmental changes in distribution pattern

The localisation of insulin receptors (IR) was investigated on cryosections of human non-pathologic first trimester and full term placentae by indirect immunohistochemistry with three different monoclonal antibodies (MABS). In placentae from 6 to 10 weeks post-menstruation (p-m.), only syncytiotrophoblast was stained, predominantly that of mesenchymal villi and syncytial sprouts, which are areas of high proliferative activity. In placentae from 11 to 14 weeks p-m., endothelial cells commenced to react with the IR MABS and the syncytiotrophoblast was less intensely labelled than at weeks 6 to 10 p-m. In term placentae, the microvillous membrane of the syncytiotrophoblast showed only patches of weak immunoreactivity. In contrast, the endothelial cells in the placenta but not in the umbilical cord were strongly stained. The amniotic epithelium in the chorionic plate and fibroblasts in the stroma were conspicuously labelled. The data indicate: (1) the receptor density on villous syncytiotrophoblast decreases and that of fetal endothelium increases throughout gestation; (2) syncytiotrophoblast of human term placentae expresses a low level per unit area of surface IR; and (3) the majority of IR in human term placentae is located in fetal endothelium. Apart from yet unknown functional effects of maternal and fetal insulin at the placental barrier, the results suggest a growth promoting effect on the trophoblast of maternal insulin in first trimester as well as developmental effects of fetal insulin on the feto-placental vessels at term.     

Immunohistochemistry of carbonic anhydrase in human placenta and fetal membranes

The localization of human carbonic anhydrase (CA) isoenzymes HCA I, HCA II, and rat CA II have been studied in human umbilical cord, chorion laeve including amnion and placenta from first and second trimester and also from term pregnancies. Detection techniques of immunofluorescence and immunoperoxidase were used in cryostat and paraffin sections. Both isoenzymes were found in the villous syncytiotrophoblast throughout pregnancy. HCA I staining patterns in the villous endothelium were highly variable whereas increasing immunoreactivity levels of endothelial HCA II were detected as pregnancy advances. The extravillous cytotrophoblast showed generally weaker levels of immunoreactivity. In amnionic epithelium of membranes, chorionic plate and umbilical cord, higher activities for HCA I, HCA II and rat CA II were found than in all other localizations. Our findings emphasize the importance of enzyme mediated bicarbonate/CO₂ removal from the feto-placental unit as opposed to simple bicarbonate diffusion or carrier mediated transport. As effective transfer routes should be considered not only umbilical cord — placental villi — intervillous space, but also fetal kidney — amnionic fluid — amnion — uterine vessels.     

Expression of VEGF-C and activation of its receptors VEGFR-2 and VEGFR-3 in trophoblast

Placental villous development requires the co-ordinated action of angiogenic factors on both endothelial and trophoblast cells. Like vascular endothelial growth factor (VEGF), VEGF-C increases vascular permeability, stimulates endothelial cell proliferation and migration. In the present study, we investigated the expression of VEGF-C and its receptors VEGFR-3 and VEGFR-2 in normal and intrauterine growth-restricted (IUGR) placenta. Immunolocalisation studies showed that like VEGF and VEGFR-1, VEGF-C, VEGFR-3 and VEGFR-2 co-localised to the syncytiotrophoblast, to cells in the maternal decidua, as well as to the endothelium of the large placental blood vessels. Western blot analysis demonstrated a significant decrease in placental VEGF-C and VEGFR-3 protein expression in severe IUGR as compared to gestationally-matched third trimester pregnancies. Conditioned medium from VEGF-C producing pancreatic carcinoma (Suit-2) and endometrial epithelial (Hec-1B) cell lines caused an increased association of the phosphorylated extracellular signal regulated kinase (ERK) in VEGFR-3 immunoprecipitates from spontaneously transformed first trimester trophoblast cells. VEGF121 caused dose-dependant phosphorylation of VEGFR-2 in trophoblast cells as well as stimulating DNA synthesis. In addition, premixing VEGF165 with heparin sulphate proteoglycan potentiated trophoblast proliferation and the association of phospho-ERK with the VEGFR-2 receptor. VEGF165-mediated DNA synthesis was inhibited by anti-VEGFR-2 neutralising antibody. The results demonstrate functional VEGFR-2 and VEGFR-3 receptors on trophoblast and suggest that the decreased expression of VEGF-C and VEGFR-3 may contribute to the abnormal villous development observed in IUGR placenta.     

Human placental transthyretin in fetal growth restriction in combination with preeclampsia and the HELLP syndrome

Fetal growth restriction is a serious, still poorly understood pregnancy-related pathology often associated with preeclampsia. Recent studies speculate on the role of human transthyretin, a carrier protein for thyroxin and retinol binding protein, in the etiology of both pregnancy pathologies. Objective was to investigate the localization and abundance of transthyretin (TTR) in placentas of pregnancies suffering from fetal growth restriction with and without preeclampsia and HELLP. This was a retrospective case control study on human paraffin-embedded placentas from pregnancies with a gestational age at delivery between the 24th and 34th week of gestation. 16 placentas were included in this study, 11 cases and 5 from normotensive pregnancies as controls. Cases were divided into three groups: four from early onset idiopathic intrauterine growth restriction (IUGR), four from early-onset severe preeclampsia (PE), and three from early-onset IUGR with preeclampsia plus HELLP syndrome. Distribution and abundance of TTR were investigated by means of immunohistochemistry. Semi quantitative analysis of TTR staining of placental sections revealed that TTR was mostly expressed in the villous trophoblast covering placental villi. Only weak staining of TTR in villous stroma could be detected. The comparison of placentas revealed that in pure IUGR and severe PE there is a much stronger TTR reactivity compared to controls and cases with IUGR?+?PE?+?HELLP. Concluding, the study showed that TTR is dysregulated in cases of IUGR and severe early onset preeclampsia. Interestingly, TTR expression is not affected in cases with HELLP syndrome that reveal the same staining intensities as age-matched controls.