Angiogenesis and intrauterine growth restriction

Trophoblast-derived factors drive human mesenchymal stem cell differentiation along an endothelial lineage: A model of early placental vasculogenesis

Mechanisms controlling the process and patterning of blood vessel development in the placenta remain largely unknown. The close physical proximity of early blood vessels observed in the placenta and the cytotrophoblast, as well as the reported production of vasculogenic growth factors by the latter, suggests that signalling between these two niches may be important. Here, we have developed an in vitro model to address the hypothesis that the cytotrophoblast, by the secretion of soluble factors, drives differentiation of resident sub-trophoblastic mesenchymal stem cells (MSCs) along a vascular lineage, thereby establishing feto-placental circulation. BM-MSCs (a readily available model for placental stem cells) were treated with conditioned medium containing the secretome from human BeWo trophoblast cells, or endothelial growth medium (EGM2) supplemented with exogenous growth factors (VEGF, IGF1 and EGF) for 10-12 days. Trophoblast-conditioned media, found to contain detectable concentrations of cytokines including VEGF, uPAR, TIMP-1, TIMP-2, IL6 and placental growth factor, induced the expression of the endothelial genes CD31, von Willibrand factor (vWF), FLT-1, VEGFR2 and VE-Cadherin. Upregulation of vWF protein was also detected following growth in trophoblast-conditioned media, using immunocytochemistry. Wound healing (migration assay) and Matrigel-tube formation assays confirmed that the BM-MSCs cultured in trophoblast-conditioned media exhibited functional measures of endothelial cells in addition to expressing relevant markers. Identification of key trophoblast-secreted factors and their promotion of endothelial differentiation in BM-MSCs helps advance our theories regarding the close relationship of the mesenchymal stem cell-cytotrophoblast niche in coordinating the complex angiogenic events that occur in the placenta. The in vitro model presented here provides an accessible and reproducible tool for further investigations into placental development.

Homeobox genes in the human placenta: Twists and turns on the path to find novel targets

Fetal growth restriction (FGR) is a clinically important human pregnancy disorder that is thought to originate early in pregnancy and while its aetiology is not well understood, the disorder is associated with placental insufficiency. Currently treatment for FGR is limited by increased surveillance using ultrasound monitoring and premature delivery, or corticosteroid medication in the third trimester to prolong pregnancy. There is a pressing need for novel strategies to detect and treat FGR at its early stage. Homeobox genes are well established as master regulators of early embryonic development and increasing evidence suggests they are also important in regulating early placental development. Most important is that specific homeobox genes are abnormally expressed in human FGR. This review focusses on identifying the molecular pathways controlled by homeobox genes in the normal and FGR-affected placenta. This information will begin to address the knowledge gap in the molecular aetiology of FGR and lay the foundation for identifying potential diagnostic and therapeutic targets.

Biochemical markers for prediction of the first half pregnancy losses: a review

Objective

26% of all pregnancies end in miscarriage, and up to 10% of clinically diagnosed pregnancies, and recurrent pregnancy loss is 5% among couples of childbearing ages. Although there are several known causes of pregnancy loss in the first half, including recurrent pregnancy loss, including parental chromosomal abnormalities, uterine malformations, endocrinological disorders, and immunological abnormalities, about half of the cases of pregnancy loss in its first half remain unexplained.

Methods

The review includes observational controlled studies (case-control or cohort, longitudinal studies, reviews, meta-analyses), which include the study of biochemical factors for predicting pregnancy losses in the first half, in singlet pregnancy. The Newcastle-Ottawa Scale (NOS) was used to assess the research quality.

Results

Finally, 27 studies were included in the review, which has 134904 examined patients. The results of the review include estimates of β-human chorionic gonadotropin, progesterone, pregnancy-associated protein - A, angiogenic vascular factors, estradiol, α-fetoprotein, homocysteine and CA-125 as a predictors or markers of the first half pregnancy losses.

Conclusion

It may be concluded that to date, research data indicate the unavailability of any reliable biochemical marker for predicting pregnancy losses in its first half and require either a combination of them or comparison with clinical evidence. A fairly new model shall be considered for the assessment of α-fetoprotein in vaginal blood, which may have great prospects in predicting spontaneous miscarriages.

Mtnr1b deletion disrupts placental angiogenesis through the VEGF signaling pathway leading to fetal growth restriction

The placenta, as a "transit station" between mother and fetus, has functions delivering nutrients, excreting metabolic wastes and secreting hormones. A healthy placenta is essential for fetal growth and development while the melatonergic system seems to play a critical physiological role in this organ since melatonin, its synthetic enzymes and receptors are present in the placenta. In current study, Mtnr1a and Mtnr1b knockout mice were constructed to explore the potential roles of melatonergic system played on the placental function and intrauterine growth retardation (IUGR). The result showed that Mtnr1a knockout had little effect on placental function while Mtnr1b knockout reduced placental efficiency and increased IUGR. Considering the extremely high incidence of IURG in sows, the pregnant sows were treated with melatonin. This treatment reduced the incidence of IUGR. All the evidence suggests that the intact melatonergic system in placenta is required for its function. Mechanistical studies uncovered that Mtnr1b knockout increased placental oxidative stress and apoptosis but reduced the angiogenesis. The RNA sequencing combined with histochemistry study identified the reduced angiogenesis and placental vascular density in Mtnr1b knockout mice. These alterations were mediated by the disrupted STAT3/VEGFR2/PI3K/AKT pathway, i.e., Mtnr1b knockout reduced the phosphorylation of STAT3 which is the promotor of VEGFR2. The downregulated VEGFR2 and its downstream elements of PI3K and AKT expressions, then, jeopardizes the angiogenesis and placental development.

Molecular regulators of defective placental and cardiovascular development in fetal growth restriction

Placental insufficiency is one of the major causes of fetal growth restriction (FGR), a significant pregnancy disorder in which the fetus fails to achieve its full growth potential in utero. As well as the acute consequences of being born too small, affected offspring are at increased risk of cardiovascular disease, diabetes and other chronic diseases in later life. The placenta and heart develop concurrently, therefore placental maldevelopment and function in FGR may have profound effect on the growth and differentiation of many organ systems, including the heart. Hence, understanding the key molecular players that are synergistically linked in the development of the placenta and heart is critical. This review highlights the key growth factors, angiogenic molecules and transcription factors that are common causes of defective placental and cardiovascular development.

Dysregulation of miRNA-mRNA expression in fetal growth restriction in a caloric restricted mouse model

Fetal growth restriction (FGR) is associated with aberrant placentation and accounts for a significant proportion of perinatal deaths. microRNAs have been shown to be dysregulated in FGR. The purpose of this study was to determine microRNA-regulated molecular pathways altered using a caloric restricted mouse model of FGR. Pregnant mice were subjected to a 50% caloric restricted diet beginning at E9. At E18.5, RNA sequencing of placental tissue was performed to identify differences in gene expression between caloric restricted and control placentas. Significant differences in gene expression between caloric restricted and control placentas were observed in 228 of the 1546 (14.7%) microRNAs. Functional analysis of microRNA-mRNA interactions demonstrated enrichment of several biological pathways with oxidative stress, apoptosis, and autophagy pathways upregulated and angiogenesis and signal transduction pathways downregulated. Ingenuity pathway analysis also suggested that ID1 signaling, a pathway integral for trophoblast differentiation, is also dysregulated in caloric restricted placentas. Thus, a maternal caloric restriction mouse model of FGR results in aberrant microRNA-regulated molecular pathways associated with angiogenesis, oxidative stress, signal transduction, apoptosis, and cell differentiation. As several of these pathways are dysregulated in human FGR, our findings suggest that this model may provide an excellent means to study placental microRNA derangements seen in FGR.

Angiogenic and Inflammatory microRNA Regulation in a Mouse Model of Fetal Growth Restriction

INTRODUCTION

Fetal growth restriction (FGR) is associated with impaired angiogenesis and chronic inflammation. MicroRNAs (miRs) are short noncoding RNAs that regulate gene expression at the post-transcriptional level by targeting messenger RNA (mRNA) for degradation or by suppressing translation. We hypothesize that dysregulation of miR-15b, an antiangiogenic miR, and miR-146a, an anti-inflammatory miR, are associated with the FGR's pathogenesis.

METHODS

Pregnant mice were provided ad libitum access to food between E1 and E8. From E9-E18, dams received either a 50% caloric restricted diet (FGR) or continued ad libitum access (controls). Placentas were harvested at E18.5 and total RNA was extracted. Gene expression levels of miRs and mRNAs were compared between FGR and control placentas.

RESULTS

Placentas affected by FGR demonstrated increased expression of miR-15b. Vascular endothelial growth factor alpha, which is downregulated in response to increased levels of miR-15b, was suppressed. The anti-inflammatory miR, miR-146a, was downregulated, resulting in upregulation of proinflammatory (IL-6, IL-8, and NFkB1) and oxidative stress (HIF-1α, SOD2, and Nox2) mediators.

CONCLUSIONS

Aberrant angiogenesis and chronic inflammation seen in FGR appear to be associated with dysregulated miR-15b and miR-146a gene expression, respectively. This observation suggests these miRs play a post-transcriptional regulatory role in FGR, providing an insight into possible therapeutic targets.

Predictive value of the sFlt‑1/PlGF ratio in women with suspected preeclampsia: An update (Review)

Preeclampsia (PE) is a major complication of pregnancy with an incidence rate of 2‑8% and is a leading cause of maternal mortality and morbidity. The various consequences of severe preeclampsia for the fetus, neonate and child include intrauterine growth retardation (IUGR), fetal hypoxia, oligohydramnios, intrauterine fetal demise, increased perinatal mortality and morbidity, neurodevelopmental disorders and even irreversible brain damage (cerebral palsy). A number of studies have demonstrated that differences in maternal serum concentrations of angiogenic factors between preeclampsia and normotensive pregnancies can be used as biomarkers, either alone or in combination with other markers, to predict the development of PE. The presence in the maternal circulation of two proteins of placental origin, placental growth factor (PlGF) and soluble fms‑like tyrosine kinase 1 (sFlt‑1), has been shown to be of clinical value, as the sFlt‑1/PlGF ratio appears to be the optimal predictive tool for the development of PE. The measurement of their concentration in maternal serum in screening models, serves as predictive marker for the development of PE or IUGR later in gestation. However, further research is required to improve its clinical applicability and provide guidelines for its use worldwide to achieve more consistent clinical management of women with PE.

Impact of timing and severity of COVID-19 infection in pregnancy on intrauterine fetal growth- a registry-based study from Qatar

BACKGROUND

The novel coronavirus disease (COVID-19) pandemic has impacted pregnant women, increasing maternal and neonatal morbidity. The placenta is a potential target for the pathophysiological processes due to the increased thrombotic inflammatory activation and inadequate uteroplacental perfusion and oxygenation, potentially causing intrauterine growth restriction. This study investigates the impact of gestational age at diagnosis of COVID-19 and the presence of symptoms on intrauterine fetal growth in pregnant women.

METHODS

A retrospective review of COVID-19 positive pregnant women in Qatar from March 2020 to March 2021 was conducted. They were divided based on trimester of pregnancy in which they were infected. The outcomes included birthweight, customised fetal birthweight centiles, small for gestational age (SGA) baby and daily growth increments, compared between the trimesters and between symptomatic and asymptomatic women.

RESULTS

In our cohort, 218 women (20.5%) were infected in the first trimester, 399 (37.5%) in the second and 446 (42%) in the third. Women in the second trimester were significantly younger and symptomatic. Women infected in the first trimester were least likely to have diabetes. The mean birthweight, risk of SGA (11.5% vs 10% vs 14.6%, p = 0.302), and median customized growth centiles (47.6% vs 45.9% vs 46.1%)were similar between the groups. Symptomatic women had significantly lower mean birthweight (3147 gms vs 3222 gms) and median birthweight centiles (43.9% vs 54.0%)compared to the asymptomatic (p<0.05 for both). In women infected within 20 weeks of gestation, a delay in daily fetal growth increments was noted with symptomatic disease, although not statistically significant.

CONCLUSION

This study shows that women with symptomatic disease had lower birth centiles and birth weights. This was regardless of the gestational age at which they were infected. Early symptomatic disease seems to have an impact on fetal growth velocity; however, larger studies are needed to corroborate these findings.

Placental angiogenesis, IUGR & CMV awareness in Iraqi women

The placenta is considered the first interface between mother and fetus, and a normal placenta is essential for pregnancy without complications. IUGR is considered the most common condition recognized in complicated pregnancy and accounts for 26% or more of stillbirth. The current study aims to explore the presence of IUGR and placental angiogenesis by investigating the expression of VEGF and eNOS in both placenta of IUGR of CMV-infected mother and placenta of normal mother in relation to awareness of CMV in Iraqi women.

The expressions of VEGF and e NOS was studied using the avidin-biotin-peroxidase technique, while awareness was studied using 10-minute surveys in Al-Karkh directorate (Baghdad) to investigate their knowledge of CMV infection in relation to the level of education and economic status.

The expression of angiogenic factors (VEGF, eNOS) was significant in syncitiotrophoblasts, smooth muscle cells and corionic villous stromal cells, and was significant in unaware, low-educated women with low income. Increased expression of angiogenic factors of IUGR babies may be a result of unawareness of CMV infection, which leads to dysregulation of angiogenic factors, and, subsequently, to inadequate placental vascularization.

Maternal PFOS exposure during rat pregnancy causes hypersensitivity to angiotensin II and attenuation of endothelium-dependent vasodilation in the uterine arteries

Epidemiological studies show a strong association between environmental exposure to perfluorooctane sulfonic acid (PFOS) and preeclampsia and fetal growth restriction; however, the underlying mechanisms are unclear. We tested the hypothesis that gestational PFOS exposure leads to pregnancy complications via alterations in uterine vascular endothelium-independent angiotensin II-related mechanisms and endothelium-derived factors such as nitric oxide. Pregnant Sprague Dawley rats were exposed to PFOS 0.005, 0.05, 0.5, 5, 10, and 50 μg/mL through drinking water from gestational day 4 to 20, and dams with PFOS 50 μg/mL were used to assess mechanisms. PFOS exposure dose-dependently increased maternal blood pressure but decreased fetal weights. Uterine artery blood flow was lower and resistance index was higher in the PFOS dams. In PFOS dams, uterine artery contractile responses to angiotensin II were significantly greater, whereas contractile responses to K+ depolarization and phenylephrine were unaffected. Plasma angiotensin II levels were not significantly different between control and PFOS dams; however, PFOS exposure significantly increased AGTR1 and decreased AGTR2 protein levels in uterine arteries. Endothelium-dependent relaxation response to acetylcholine was significantly reduced with decreased endothelial nitric oxide synthase expression in the uterine arteries of PFOS dams. Left ventricular hypertrophy and fibrosis were observed, along with increased ejection fraction and fractional shortening in PFOS dams. These results suggest that elevated maternal PFOS levels decrease uterine blood flow and increase vascular resistance via heightened angiotensin II-mediated vasoconstriction and impaired endothelium-dependent vasodilation, which provides a molecular mechanism linking elevated maternal PFOS levels with gestational hypertension and fetal growth restriction.

The endocannabinoids anandamide and 2-arachidonoylglycerol modulate the expression of angiogenic factors on HTR8/SVneo placental cells

The interest on the endocannabinoid system (ECS) in human reproduction has grown due to its involvement in placenta development, which led to growing concerns over pregnant cannabis consumer's impact on pregnancy outcome. The endocannabinoids anandamide (AEA) and 2-arachidonoylglycerol (2-AG) modulate placental trophoblast proliferation and apoptosis. However, their role on other placentation events such as angiogenesis and invasion are unknown. Using the human extravillous trophoblast HTR-8/SVneo cells, a well-accepted model of first trimester extravillous trophoblast (EVT), this study aims to investigate whether AEA and 2-AG can modulate the expression of angiogenesis- and invasion-related factors. Transcript analysis of angiogenic factors of the vascular endothelial growth factor (VEGF) and matrix metalloproteinase (MMP) protein family demonstrated the ability of AEA to increase VEGF-C and VEGFR3 expression via cannabinoid receptors CB1 and CB2 while the placental growth factor (PlGF) was increased through CB1. Moreover, an increase in VEGFR1, sFLT1, VEGFR2, MMP-2 and TIMP-1 independent of cannabinoid receptor activation was verified. However, 2-AG only increased PlGF transcript through CB1/CB2 activation. Both endocannabinoids stimulated HTR8/SVneo endothelial-like tube formation. As for the wound healing assay, only 2-AG was able to increase the percentage of wound closure. Moreover, the data demonstrated that both AEA and 2-AG, via cannabinoid receptors, activated the STAT3 signaling pathway. Distinct effects were observed on transcription factor HIF-1α and AKT phosphorylation that decreased with both endocannabinoids. Although different angiogenic and migration factors are affected the results obtained in this work showcase once more the ability of the endocannabinoids to modulate key processes in placental physiology.

Reduced volumetric parameters of the placenta and extravillous trophoblastic cells in complicated pregnancies may lead to intrauterine growth restriction and small for gestational age birth

AIM

We undertook this study to determine quantitative changes of the placenta, focusing on extravillous trophoblastic cells (EVTs) in pregnancies with intrauterine growth restriction (IUGR) and small for gestational age (SGA) compared to the control group.

METHODS

Placentas from pregnancies complicated with SGA-IUGR (n = 10) and control group (n = 10) were obtained after cesarean surgery and evaluated using stereological assays after routine tissue processing and Masson's trichrome staining. Mann-Whitney U-test was employed, and the level of statistical significance was set at p <0.05.

RESULTS

Our results showed that the volumetric parameters, including the total volume and volume density of chorionic villi, intervillous spaces, blood vessels in chorionic villi, and syncytiotrophoblast, decreased significantly in the SGA-IUGR group compared to control placentas (p <0.05). Also, total volume, number of EVTs, volume, the diameter of cytoplasm, and diameter of the nucleus in these cells were significantly lower in the SGA-IUGR group (p <0.05). In addition, the nucleus to cytoplasm ratio of EVTs was also higher in the SGA-IUGR group (p <0.05).

CONCLUSIONS

There are several significant histological and stereological differences in the placenta, particularly its EVTs from the SGA-IUGR group compared to the control group. It seems that histological changes in the placental tissues could be helpful for the retrospective explanations of pregnancy complications.

Collagen and Microvascularization in Placentas From Young and Older Mares

In older mares, increasing collagen fibers (fibrosis) in the endometrium and oviduct predisposes to sub-fertility and infertility. In this study, (i) gene transcription of collagen (qPCR: COL1A1, COL1A2, COL3A1, COL5A1); (ii) total collagen protein (hydroxyproline); (iii) collagen distribution (Picrosirius red staining; polarized light microscopy); and (iv) microvascular density (Periodic acid-Schiff staining), were evaluated in mares' placenta, and related to mares age, and placenta and neonate weights. Samples were collected from the gravid horn, non-gravid horn, and body of the placenta from younger (n = 7), and older mares (n = 9) of different breeds. Transcripts of COL1A1, COL3A1 and COL5A1, total collagen protein, chorionic plate connective tissue thickness, and microvascularization increased in the gravid horn of older mares' placentas, compared to the youngest (P < 0.05). Although in other species placenta fibrosis may indicate placental insufficiency and reduced neonate weight, this was not observed here. It appears that older fertile mares, with more parities, may develop a heavier, more vascularized functional placenta with more collagen, throughout a longer gestation, which enables the delivery of heavier foals. Thus, these features might represent morphological and physiological adaptations of older fertile mares' placentas to provide the appropriate nutrition to the equine fetus.

Overexpression of microRNAs miR-25-3p, miR-185-5p and miR-132-3p in Late Onset Fetal Growth Restriction, Validation of Results and Study of the Biochemical Pathways Involved

In a prospective study, 48 fetuses were evaluated with Doppler ultrasound after 34 weeks and classified, according to the cerebroplacental ratio (CPR) and estimated fetal weight (EFW), into fetuses with normal growth and fetuses with late-onset fetal growth restriction (LO-FGR). Overexpression of miRNAs from neonatal cord blood belonging to LO-FGR fetuses, was validated by real-time PCR. In addition, functional characterization of overexpressed miRNAs was performed by analyzing overrepresented pathways, gene ontologies, and prioritization of synergistically working miRNAs. Three miRNAs: miR-25-3p, miR-185-5p and miR-132-3p, were significantly overexpressed in cord blood of LO-FGR fetuses. Pathway and gene ontology analysis revealed over-representation of certain molecular pathways associated with cardiac development and neuron death. In addition, prioritization of synergistically working miRNAs highlighted the importance of miR-185-5p and miR-25-3p in cholesterol efflux and starvation responses associated with LO-FGR phenotypes. Evaluation of miR-25-3p; miR-132-3p and miR-185-5p might serve as molecular biomarkers for the diagnosis and management of LO-FGR; improving the understanding of its influence on adult disease.

Perinatal Outcomes Among Patients With Sepsis During Pregnancy

IMPORTANCE

Rates of maternal sepsis are increasing, and prior studies of maternal sepsis have focused on immediate maternal morbidity and mortality associated with sepsis during delivery admission. There are no data on pregnancy outcomes among individuals who recover from their infections prior to delivery.

OBJECTIVE

To describe perinatal outcomes among patients with antepartum sepsis who did not deliver during their infection hospitalization.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study was conducted using data from August 1, 2012, to August 1, 2018, at an academic referral center in San Francisco, California. Included patients were all individuals with nonanomalous, singleton pregnancies who delivered after 20 weeks' gestation during the study period. Data were analyzed from March 2020 through March 2021.

EXPOSURES

Antepartum admission for infection with clinical concern for sepsis and hospital discharge prior to delivery.

MAIN OUTCOMES AND MEASURES

The primary outcome was a composite of perinatal outcomes associated with placental dysfunction and consisted of 1 or more of the following: fetal growth restriction, oligohydramnios, hypertensive disease of pregnancy, cesarean delivery for fetal indication, child who is small for gestational age, or stillbirth.

RESULTS

Among 14 565 patients with nonanomalous singleton pregnancies (mean [SD] age at delivery, 33.1 [5.2] years), 59 individuals (0.4%) were in the sepsis group and 14 506 individuals (99.6%) were in the nonsepsis group; 8533 individuals (59.0%) were nulliparous. Patients with sepsis, compared with patients in the reference group, were younger (mean [SD] age at delivery, 30.6 [5.7] years vs 33.1 [5.2] years; P < .001), were more likely to have pregestational diabetes (5 individuals [8.5%] vs 233 individuals [1.6%]; P = .003), and had higher mean (SD) pregestational body mass index scores (26.1 [6.1] vs 24.4 [5.9]; P = .03). In the sepsis group, the most common infections were urinary tract infections (24 patients [40.7%]) and pulmonary infections (22 patients [37.3%]). Among patients with sepsis, 5 individuals (8.5%) were admitted to the intensive care unit, the mean (SD) gestational age at infection was 24.6 (9.0) weeks, and the median (interquartile range) time from infection to delivery was 82 (42-147) days. Antepartum sepsis was associated with higher odds of placental dysfunction (21 patients [35.6%] vs 3450 patients [23.8%]; odds ratio, 1.77; 95% CI, 1.04-3.02; P = .04). On multivariable logistic regression analysis, antepartum sepsis was an independent factor associated with placental dysfunction (adjusted odds ratio, 1.88; 95% CI, 1.10-3.23; P = .02) after adjusting for possible confounders.

CONCLUSIONS AND RELEVANCE

This study found that pregnancies complicated by antepartum sepsis were associated with higher odds of placental dysfunction. These findings suggest that increased antenatal surveillance should be considered for these patients.

Mesenchymal Stem/Stromal Cells from the Placentae of Growth Restricted Pregnancies Are Poor Stimulators of Angiogenesis

The extensively branched vascular network within the placenta is vital for materno-fetal exchange, and inadequate development of this network is implicated in the pregnancy disorder fetal growth restriction (FGR), where babies are born pathologically small. Placental mesenchymal stem/stromal cells (pMSCs) and placental macrophages both reside in close proximity to blood vessels within the placenta, where they are thought to promote angiogenesis via paracrine mechanisms. However, the relationship between pMSCs, macrophages and placental vascular development has not yet been examined. We aimed to determine if inadequate paracrine stimulation of placental vascular development by pMSCs and macrophages during pregnancy may contribute to the inadequate vascularisation seen in FGR. Media conditioned by MSCs from FGR placentae significantly inhibited endothelial tube formation, compared to conditioned media derived from normal pMSCs. Similarly, macrophages exposed to media conditioned by FGR pMSCs were less able to stimulate endothelial tube formation in comparison to macrophages exposed to media conditioned by normal pMSCs. While MSCs from normal placentae produce a combination of angiogenic and anti-angiogenic cytokines, there were no significant differences in the secretion of the anti-angiogenic cytokines thrombospondin-1, insulin growth factor binding protein-4, or decorin between normal and FGR pMSCs that could explain how FGR pMSCs inhibited endothelial tube formation. Together, these data suggest a dysregulation in the secretion of paracrine factors by pMSCs in FGR placentae. These findings illustrate how cross talk between pro-angiogenic cell types in the placenta may be crucial for adequate angiogenesis.

DNA Methylation and gene expression patterns are widely altered in fetal growth restriction and associated with FGR development

Fetal growth restriction (FGR) is the failure of the fetus toachieve its genetically determined growth potential, which increasesrisks for a variety of genetic diseases, such as type 2 diabetes mellitus, coronary artery disease, and stroke, during the lifetime. The dysregulation of DNA methylationis known to interact with environmental fluctuations, affect gene expressions comprehensively, and be fatal to fetus development in specific cases. Therefore, we set out to find out epigenetic and transcriptomic alterations associated with FGR development. We found a set of differentially expressed genes associated with differentially methylated regions in placentae and cord blood samples. Using dimensional reduction analysis, the expression and methylation variables of the epigenetically altered genes classified the FGR samples from the controls. These genes were also enriched in the biological pathways such as metabolism and developmental processes related to FGR. Furthermore, three genes of INS, MEG3, and ZFP36L2 are implicated in epigenetic imprinting, which has been associated with FGR. These results strongly suggest that DNA methylation is highly dysregulated during FGR development, and abnormal DNA methylation patterns are likely to alter gene expression.

The Emerging Role of the Prokineticins and Homeobox Genes in the Vascularization of the Placenta: Physiological and Pathological Aspects

Vasculogenesis and angiogenesis are key processes of placental development, which occur throughout pregnancy. Placental vasculogenesis occurs during the first trimester of pregnancy culminating in the formation of hemangioblasts from intra-villous stem cells. Placental angiogenesis occurs subsequently, forming new blood vessels from existing ones. Angiogenesis also takes place at the fetomaternal interface, allowing essential spiral arteriole remodeling to establish the fetomaternal circulation. Vasculogenesis and angiogenesis in animal models and in humans have been studied in a wide variety of in vitro, physiological and pathological conditions, with a focus on the pro- and anti-angiogenic factors that control these processes. Recent studies revealed roles for new families of proteins, including direct participants such as the prokineticin family, and regulators of these processes such as the homeobox genes. This review summarizes recent advances in understanding the molecular mechanisms of actions of these families of proteins. Over the past decade, evidence suggests increased production of placental anti-angiogenic factors, as well as angiogenic factors are associated with fetal growth restriction (FGR) and preeclampsia (PE): the most threatening pathologies of human pregnancy with systemic vascular dysfunction. This review also reports novel clinical strategies targeting members of these family of proteins to treat PE and its consequent effects on the maternal vascular system.

Perivascular Stem Cell-Derived Cyclophilin A Improves Uterine Environment with Asherman's Syndrome via HIF1α-Dependent Angiogenesis

Asherman's syndrome (AS) is characterized by intrauterine adhesions or fibrosis resulting from scarring inside the endometrium. AS is associated with infertility, recurrent miscarriage, and placental abnormalities. Although mesenchymal stem cells show therapeutic promise for the treatment of AS, the molecular mechanisms underlying its pathophysiology remain unclear. We ascertained that mice with AS, like human patients with AS, suffer from extensive fibrosis, oligo/amenorrhea, and infertility. Human perivascular stem cells (hPVSCs) from umbilical cords repaired uterine damage in mice with AS, regardless of their delivery routes. In mice with AS, embryo implantation is aberrantly deferred, which leads to intrauterine growth restriction followed by no delivery at term. hPVSC administration significantly improved implantation defects and subsequent poor pregnancy outcomes via hypoxia inducible factor 1α (HIF1α)-dependent angiogenesis in a dose-dependent manner. Pharmacologic inhibition of HIF1α activity hindered hPVSC actions on pregnancy outcomes, whereas stabilization of HIF1α activity facilitated such actions. Furthermore, therapeutic effects of hPVSCs were not observed in uterine-specific HIF1α-knockout mice with AS. Secretome analyses of hPVSCs identified cyclophilin-A as the major paracrine factor for hPVSC therapy via HIF1α-dependent angiogenesis. Collectively, we demonstrate that hPVSCs-derived cyclophilin-A facilitates HIF1α-dependent angiogenesis to ameliorate compromised uterine environments in mice with AS, representing the major pathophysiologic features of humans with AS.

A bibliometric analysis of Intrauterine Growth Restriction research

Intrauterine growth restriction (IUGR) is not a new subject in pregnancy. Nevertheless, this concept has newly begun to be integrated into pregnancy studies. We recognized articles that were published in English from 1977 to 2019 through electronic searches of the Web of Science™ database. The WoS database was searched for all published articles that compared preeclampsia from 1977 to January 2020. About 1469 documents in obstetrics and gynecology areas were analyzed in WoS database. VOSviewer software was employed to visualize the networks. The survey resulted in a 1469 published documents from 1977 to 2020. 'Gratacos' from Spain and 'Cetin' from Italy contributed the most publications. The greatest contribution came from the 'USA' (n = 498), 'Italy' (n = 155), and 'England' (n = 147). Furthermore, our results found that among these journals, the 'AJOG' (n = 318) and the 'Reproductive Sciences' (n = 209) published the largest number of papers. The top 100 most cited papers showed that 30% were reported in the 'AJOG'. About half the articles were published in the last decade and the most common studies were research paper (77%). The co-occurrence and co-citation analysis showed that the study formed four clusters. Finally, the strategic map was designed. We found that there existed an increasing trend in the large amount of publication on IUGR from 1977 to 2020. The number of studies in IUGR has substantially improved in the last decade. Authors from the 'USA' appeared the most proactive in addressing the IUGR area. By studying these articles, we propose important to support not only for grinding the IUGR challenges field but also for designing a new trend in this area.

Differential Secretion of Angiopoietic Factors and Expression of MicroRNA in Umbilical Cord Blood from Healthy Appropriate-For-Gestational-Age Preterm and Term Newborns-in Search of Biomarkers of Angiogenesis-Related Processes in Preterm Birth

Objectives: Premature birth, defined as less than 37 weeks gestation, affects approximately 12% of all live births around the world. Advances in neonatal care have resulted in the increased survival of infants born prematurely. Although prematurity is a known risk factor for different cardiovascular diseases, little is known about the pathophysiology of vasculature during premature gestation and angiopoietic factors network during premature birth. Aims: The objective of this study was to determine whether the profile of several pro-angiogenic and anti-angiogenic factors in umbilical cord blood (UCB) is different in healthy appropriate-for-gestational-age preterm newborns and normal term babies. The second aim of this study was to investigate the microRNA (miRNAs) expression profile in UCB from preterm labor and to detect miRNAs potentially taking part in control of angogenesis-related processes (Angio-MiRs). Methods: Using an immunobead Luminex assay, we simultaneously measured the concentration of Angiogenin, Angiopoietin-1, FGF-acidic, FGF-basic, PDGF-aa, PlGF, VEGF, VEGF-D, Endostatin, Thrombospondin-2, NGF, BDNF, GDNF, and NT-4 in UCB samples collected from the preterm (n = 27) and term (n = 52) delivery. In addition, the global microRNA expression in peripheral blood mononuclear cells (PBMCs) circulating in such UCB samples was examined in this study using microarray MiRNA technique. Results: The concentrations of five from eight measured pro-angiogenic factors (VEGF, Angiopoietin-1, PDGF-AA, FGF-a, and FGF-b) were significantly lower in UCB from preterm newborns. On the contrary, two angiostatic factors (Endostatin and Thrombospondin-2) were significantly up-regulated in preterm UCB. Among analyzed neurotrophins in preterm newborns, the elevated UCB concentration was found only in the case of GDNF, whereas BDNF was significantly reduced. Moreover, two angiopoietic factors, VEGF-D and PlGF, and two neurotrophins, NT4 and NGF, did not differ in concentration in preterm and term babies. We also discovered that among the significantly down-regulated miRNAs, there were several classical Angio-MiRs (inter alia MiR-125, MiR-126, MiR-145, MiR-150, or MiR155), which are involved in angiogenesis regulation in newborn after preterm delivery. Conclusions: This is the first report of simultaneous measurements of several angiopoietic factors in UCB collected from infants during preterm and term labor. Here, we observed that several pro-angiogenic factors were at lower concentration in UCB collected from preterm newborns than term babies. In contrast, the two measured angiostatic factors, Endostatin and Thrombospondin-2, were significantly higher in UCB from preterm babies. This can suggest that distinct pathophysiological contributions from differentially expressed various angiopoietic factors may determine the clinical outcomes after preterm birth. Especially, our angiogenesis-related molecules analysis indicates that preterm birth of healthy, appropriate-for-gestational-age newborns is an “anti-angiogenic state” that may provide an increased risk for improper development and function of cardiovascular system in the adulthood. This work also contributes to a better understanding of the role of miRNAs potentially involved in angiogenesis control in preterm newborns.

Perspective: L-arginine and L-citrulline Supplementation in Pregnancy: A Potential Strategy to Improve Birth Outcomes in Low-Resource Settings

The available data support the hypothesis that L-arginine or L-citrulline supplementation would be suitable for implementation in resource-constrained settings and will enhance placental vascular development and improve birth outcomes. In resource-constrained settings, the rates of adverse birth outcomes, including fetal growth restriction, preterm birth, and low birth weight, are disproportionately high. Complications resulting from preterm birth are now the leading cause of mortality in children <5 y of age worldwide. Despite the global health burden of adverse birth outcomes, few effective interventions are currently available and new strategies are urgently needed, especially for low-resource settings. L-arginine is a nutritionally essential amino acid in pregnancy and an immediate precursor of nitric oxide. During pregnancy, placental and embryonic growth increases the demand for L-arginine, which can exceed endogenous synthesis of L-arginine from L-citrulline, necessitating increased dietary intake. In many low-resource settings, dietary intake of L-arginine in pregnancy is inadequate owing to widespread protein malnutrition and depletion of endogenous L-arginine due to maternal infections, in particular malaria. Here we examine the role of the L-arginine-nitric oxide biosynthetic pathway in pregnancy including placental vascular development and fetal growth. We review the evidence for the relations between altered L-arginine bioavailability and pregnancy outcomes, and strategies for arginine supplementation in pregnancy. Existing studies of L-arginine supplementation in pregnancy in high-resource settings have shown improved maternal and fetal hemodynamics, prevention of pre-eclampsia, and improved birth outcomes including higher birth weight and longer gestation. Arginine supplementation studies now need to be extended to pregnant women in low-resource settings, especially those at risk of malaria.

The Impact of Infection in Pregnancy on Placental Vascular Development and Adverse Birth Outcomes

Healthy fetal development is dependent on nutrient and oxygen transfer via the placenta. Optimal growth and function of placental vasculature is therefore essential to support in utero development. Vasculogenesis, the de novo formation of blood vessels, and angiogenesis, the branching and remodeling of existing vasculature, mediate the development and maturation of placental villi, which form the materno-fetal interface. Several lines of evidence indicate that systemic maternal infection and consequent inflammation can disrupt placental vasculogenesis and angiogenesis. The resulting alterations in placental hemodynamics impact fetal growth and contribute to poor birth outcomes including preterm delivery, small-for-gestational age (SGA), stillbirth, and low birth weight (LBW). Furthermore, pathways involved in maternal immune activation and placental vascularization parallel those involved in normal fetal development, notably neurovascular development. Therefore, immune-mediated disruption of angiogenic pathways at the materno-fetal interface may also have long-term neurological consequences for offspring. Here, we review current literature evaluating the influence of maternal infection and immune activation at the materno-fetal interface and the subsequent impact on placental vascular function and birth outcome. Immunomodulatory pathways, including chemokines and cytokines released in response to maternal infection, interact closely with the principal pathways regulating placental vascular development, including the angiopoietin-Tie-2, vascular endothelial growth factor (VEGF), and placental growth factor (PlGF) pathways. A detailed mechanistic understanding of how maternal infections impact placental and fetal development is critical to the design of effective interventions to promote placental growth and function and thereby reduce adverse birth outcomes.

CXCR4 signaling at the ovine fetal-maternal interface regulates vascularization, CD34+ cell presence, and autophagy in the endometrium†

Placenta development is characterized by extensive angiogenesis and vascularization but if these processes are compromised placental dysfunction occurs, which is the underlying cause of pregnancy complications such as preeclampsia and intrauterine growth restriction. Dysregulation of placental angiogenesis has emerged as one of the main pathophysiological features in the development of placental insufficiency and its clinical consequences. The signaling axis initiated by chemokine ligand 12 (CXCL12) and its receptor CXCR4 stimulates angiogenesis in other tissues, and may be central to placental vascularization. We hypothesized that CXCL12-CXCR4 signaling governs the pro-angiogenic placental microenvironment by coordinating production of central angiogenic factors and receptors and regulates endometrial cell survival essential for placental function and subsequent fetal longevity. The CXCR4 antagonist, AMD3100, was used to elucidate the role of CXCL12-CXCR4 signaling regarding uteroplacental vascular remodeling at the fetal-maternal interface. On day 12 postbreeding, osmotic pumps were surgically installed and delivered either AMD3100 or PBS into the uterine lumen ipsilateral to the corpus luteum. On day 20, endometrial tissues were collected, snap-frozen in liquid nitrogen, and uterine horn cross sections preserved for immunofluorescent analysis. In endometrium from ewes receiving AMD3100 infusion, the abundance of select angiogenic factors was diminished, while presence of CD34+ cells increased compared to control ewes. Ewes receiving AMD3100 infusion also exhibited less activation of Akt/mTOR signaling, and elevated LC3B-II, a marker of cellular autophagy in endometrium. This study suggests that CXCL12-CXCR4 signaling governs placental homeostasis by serving as a critical upstream mediator of vascularization and cell viability, thereby ensuring appropriate placental development.

Secondary Placental Defects in Cxadr Mutant Mice

The Coxsackie virus and adenovirus receptor (CXADR) is an adhesion molecule known for its role in virus-cell interactions, epithelial integrity, and organogenesis. Loss of Cxadr causes numerous embryonic defects in mice, notably abnormal development of the cardiovascular system, and embryonic lethality. While CXADR expression has been reported in the placenta, the precise cellular localization and function within this tissue are unknown. Since impairments in placental development and function can cause secondary cardiovascular abnormalities, a phenomenon referred to as the placenta-heart axis, it is possible placental phenotypes in Cxadr mutant embryos may underlie the reported cardiovascular defects and embryonic lethality. In the current study, we determine the cellular localization of placental Cxadr expression and whether there are placental abnormalities in the absence of Cxadr. In the placenta, CXADR is expressed specifically by trophoblast labyrinth progenitors as well as cells of the visceral yolk sac (YS). In the absence of Cxadr, we observed altered expression of angiogenic factors coupled with poor expansion of trophoblast and fetal endothelial cell subpopulations, plus diminished placental transport. Unexpectedly, preserving endogenous trophoblast Cxadr expression revealed the placental defects to be secondary to primary embryonic and/or YS phenotypes. Moreover, further tissue-restricted deletions of Cxadr suggest that the secondary placental defects are likely influenced by embryonic lineages such as the fetal endothelium or those within the extraembryonic YS vascular plexus.

Maternal total cell-free DNA in preeclampsia and fetal growth restriction: Evidence of differences in maternal response to abnormal implantation

Objectives

Preeclampsia and fetal growth restriction are obstetrical syndromes associated with abnormal placental implantation and changes in the activation status of maternal leukocytes. This study is aimed to determine by a simple, rapid fluorescent assay the changes in maternal serum total cell-free DNA (t-cfDNA) concentrations in women with preeclampsia and those with fetal growth restriction (FGR).

Study design

A cross-sectional study was conducted measuring maternal serum t-cfDNA concentrations. Women were classified into the following groups: 1) patients with preeclampsia (n = 21); 2) FGR-estimated fetal weight below the 10^thpercentile (n = 28); and 3) normal pregnancy (n = 39). Serum samples were directly assayed for t-cfDNA using a rapid fluorescent SYBR Gold assay. Elevated maternal serum t-cfDNA concentrations were defined as a cutoff>850ng/ml. Nonparametric statistics were used for analysis.

Results

Women with preeclampsia had a higher median maternal serum concentration (802 ng/ml, 400–2272 ng/ml) than women with a normal pregnancy (499 ng/ml, 0–1892 ng/ml, p = 0.004) and those with FGR (484 ng/ml, 72–2187 ng/ml, p = 0.012). Moreover, even patients with FGR <5^th percentile and abnormal Doppler had a lower median maternal serum t-cfDNA than those with preeclampsia (median 487 ng/ml, 144–1971 ng/ml, p = 0.022). The median concentration of t-cfDNA did not differ between women with a normal pregnancy and those with FGR (p = 0.54), as well as those with fetuses <5th percentile and abnormal Doppler (p = 0.7). Women with preeclampsia had a higher proportion of elevated t-cfDNA than those with a normal pregnancy (p = 0.015) and patients with FGR (p = 0.025).

Conclusions

Preeclampsia is associated with higher maternal serum t-cfDNA concentration than normal pregnancy or FGR. This observation may reflect an increased systemic activation of the maternal inflammation, rather than placental; this assumption is supported by the fact that we did not observe a significant change in the maternal serum t-cfDNA in patients with placental-mediated FGR.

The role of angiogenic markers in adverse perinatal outcomes: fresh versus frozen embryo transfers

PURPOSE

We aimed to investigate the angiogenic balance in fresh compared to frozen embryo transfers, and among neonates with adverse perinatal outcomes.

METHODS

This was a retrospective cohort study. All IVF cycles resulting in a singleton live birth at a university academic fertility center from January 1, 2011, to December 31, 2013, were examined. Concentrations of sFLT-1 and PlGF were measured in previously frozen serum specimens collected during early gestation at approximately 5 weeks gestation. Patients completed an electronic survey to detail perinatal outcome.

RESULTS

We identified 152 singleton live births (103 fresh, 49 frozen). Demographic characteristics were similar between the two groups. Ratios of sFlt-1:PlGF were not different between fresh and frozen transfers. Neonates from fresh cycles had a mean birth weight 202 g lighter (p = 0.01) than frozen cycles, after adjusting for gestational age. Among babies born with poor perinatal outcomes, there was a difference in sFlt-1:PlGF ratios after adjusting for race. In non-Asians, infants born small for gestational age (SGA) (< 10th percentile) had significantly higher sFLT-1:PLGF ratio, median ratio (0.21 vs 0.12, p = 0.016).

CONCLUSIONS

Fresh transfers were associated with lower birth weight infants compared to frozen transfers. While there was no difference in sFlt-1:PlGF ratios between fresh and frozen transfers, these ratios were significantly lower in SGA infants, suggesting an imbalance in angiogenic markers during placentation.

Genome-wide microRNA expression profiling in placentae from frozen-thawed blastocyst transfer

Background

Frozen-thawed embryo transfer (FET) is increasingly available for the improvement of the success rate of assisted reproductive technologies other than fresh embryo transfer (ET). There have been numerous findings that FET provides better obstetric and perinatal outcomes. However, the birth weight of infants conceived using FET is heavier than that of those conceived via ET. In addition, some reports have suggested that FET is associated with perinatal diseases such as placenta accreta and pregnancy-induced hypertension (PIH).

Results

In this study, we compared the microRNA (miRNA) expression profiles in term placentae derived from FET, ET, and spontaneous pregnancy (SP). We identified four miRNAs, miR-130a-3p, miR-149-5p, miR-423-5p, and miR-487b-3p, that were significantly downregulated in FET placentae compared with those from SP and ET. We found that DNA methylation of MEG3-DMR, not but IG-DMR, was associated with miRNA expression of the DLK1-DIO3 imprinted domain in the human placenta. In functional analyses, GO terms and signaling pathways related to positive regulation of gene expression, growth, development, cell migration, and type II diabetes mellitus (T2DM) were enriched.

Conclusions

This study supports the hypothesis that the process of FET may increase exposure of epigenome to external influences.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-017-0379-6) contains supplementary material, which is available to authorized users.

Expression of Biglycan in First Trimester Chorionic Villous Sampling Placental Samples and Altered Function in Telomerase-Immortalized Microvascular Endothelial Cells

OBJECTIVE

Biglycan (BGN) has reduced expression in placentae from pregnancies complicated by fetal growth restriction (FGR). We used first trimester placental samples from pregnancies with later small for gestational age (SGA) infants as a surrogate for FGR. The functional consequences of reduced BGN and the downstream targets of BGN were determined. Furthermore, the expression of targets was validated in primary placental endothelial cells isolated from FGR or control pregnancies. APPROACH AND RESULTS: BGN expression was determined using real-time polymerase chain reaction in placental tissues collected during chorionic villous sampling performed at 10 to 12 weeks' gestation from pregnancies that had known clinical outcomes, including SGA. Short-interference RNA reduced BGN expression in telomerase-immortalized microvascular endothelial cells, and the effect on proliferation, angiogenesis, and thrombin generation was determined. An angiogenesis array identified downstream targets of BGN, and their expression in control and FGR primary placental endothelial cells was validated using real-time polymerase chain reaction. Reduced BGN expression was observed in SGA placental tissues. BGN reduction decreased network formation of telomerase-immortalized microvascular endothelial cells but did not affect thrombin generation or cellular proliferation. The array identified target genes, which were further validated: angiopoetin 4 (ANGPT4), platelet-derived growth factor receptor α (PDGFRA), tumor necrosis factor superfamily member 15 (TNFSF15), angiogenin (ANG), serpin family C member 1 (SERPIN1), angiopoietin 2 (ANGPT2), and CXC motif chemokine 12 (CXCL12) in telomerase-immortalized microvascular endothelial cells and primary placental endothelial cells obtained from control and FGR pregnancies.

CONCLUSIONS

This study reports a temporal relationship between altered placental BGN expression and subsequent development of SGA. Reduction of BGN in vascular endothelial cells leads to disrupted network formation and alterations in the expression of genes involved in angiogenesis. Therefore, differential expression of these may contribute to aberrant angiogenesis in SGA pregnancies.

Angiopoietin 2 in placentation and tumor biology: The yin and yang of vascular biology

There are several parallels between placental and tumor biology. Both require rapid acquisition of a blood supply to supply oxygen and nutrients, the placenta through neoangiogenesis and tumors by co-opting the existing vasculature. In addition, successful pregnancy also requires remodeling of the maternal uterine spiral arteries. Angiopoietins (Angs) are a family of angiogenic growth factors, the best studied being Ang-1 and Ang-2, which signal through the membrane tyrosine kinase receptor Tie2, and in simple terms have opposite effects with Ang-1 acting to stabilize newly formed blood vessels and Ang-2 having a destabilizing effect. The roles of Ang-1, and in particular Ang-2 in placental and tumor biology are discussed in this review.

Oxidative stress, placental ageing-related pathologies and adverse pregnancy outcomes

Oxidative stress (OS), an imbalance between free radical generation and antioxidant defence, is recognized as a key factor in the pathogenesis of adverse pregnancy outcomes. Although OS is a common future of normal pregnancy, persistent, overwhelming OS leads to consumption and decline of antioxidants, affecting placental antioxidant capacity and reducing systems. The accumulation of OS causes damage to lipids, proteins and DNA in the placental tissue that induces a form of accelerated ageing. Premature ageing of the placenta is associated with placental insufficiency that prevents the organ meeting the needs of the foetus, and as a consequence, the viability of the foetus is compromised. This review summarizes the literature regarding the role of OS and premature placental ageing in the pathophysiology of pregnancy complications.

The role of aberrant methylation of trophoblastic stem cell origin in the pathogenesis and diagnosis of placental disorders

OBJECTIVES

The objective of the study is to investigate the role of methylation levels at promoter regions of placental vascularization genes (VEGF, EGFR, and c-jun) in pathogenesis and diagnosis of placental disorders.

METHODS

We analyzed DNA and histone methylation at promoters of VEGF, EGFR, and c-jun via methylation-sensitive high-resolution melting and chromatin immunoprecipitation assay in pregnant women with normal pregnancy in first, second, and third trimesters (n = 30 in each group) and pregnant women with pregnancy complicated with preeclampsia (n = 30) and hydatidiform mole (n = 15).

RESULTS

The higher expression of VEGF, EGFR, and c-jun in early pregnancy was observed to be independent of DNA methylation, while it was associated with H3 K9/K27 trimethylations. Also, abnormally higher expression of c-jun in GTDs was associated with lower H3K9me3 level at its promoter. Under preeclampsia conditions, we observed dysregulation of both DNA methylation and H3 trimethylation and subsequent low expression of VEGF, EGFR, and c-jun. Importantly, our promoter methylation data indicated that VEGF may act as novel fetal DNA diagnostic marker for preeclampsia and molar pregnancies in maternal plasma.

CONCLUSION

These findings emphasize the importance of dysregulated epigenetic phenomenon behind the pathologies of placental disorders and use of promoter region DNA methylation as an epigenetic marker for these pathological pregnancies. © 2016 John Wiley & Sons, Ltd.

Phenotypic and molecular characterization of intrauterine fetal growth restriction in interspecies sheep pregnancy

Interspecies pregnancies between closely related species are usually performed in livestock to obtain improved and enriched offspring. Indeed, different hybrids have been obtained for research purposes since many years ago, and the maternal-fetal interactions have been studied as a possible strategy for species preservation. The aim of this study was to characterize by physiological and molecular approaches the interspecies pregnancy between bighorn sheep () and domestic sheep (). Hybrids were obtained by artificial insemination; the blood pressure and protein urine levels were measured during the last two-thirds of gestation. After parturition, offspring and placentas were weighed and measured and cotyledons were counted and weighed and their surface area determined. Plasma samples were obtained between wk 8 and 21 of gestation to assess progesterone (P4), vascular endothelial growth factor (VEGF), and placental growth factor (PlGF) levels and cell-free RNA was isolated during the same period to assess hypoxia-inducible factor-1 α (α) gene expression. Hybrid and normal pregnancies were analyzed using physiological and molecular parameters during the last two-thirds of gestation (wk 8-21). The results show that during the measurement period, ewes with a hybrid pregnancy presented normal blood pressure and no alteration in urinary protein content. However, compared with sheep with a normal pregnancy, those with a hybrid pregnancy had a decrease in fetal and placental growth as well as in the cotyledonary surface area. Furthermore, in the hybrid group, there was placental insufficiency, characterized by a decrease in P4 production, as well as indications of endothelial dysfunction, characterized an increase in plasma levels of VEGF and PlGF as well as in plasma gene expression of α. Overall, the results indicate that hybrids of and presented intrauterine growth restriction, essentially due to altered endothelial function and chronic placental insufficiency. Further studies are necessary to overcome this primary placental dysfunction and thus obtain improved offspring for future molecular and genomic evaluations.

Inhibition of human placental endothelial cell proliferation and angiogenesis by netrin-4

INTRODUCTION

Netrin-4 is a secreted member of the laminin-related protein family, known to be involved in axonal guidance and endothelial cell survival, proliferation, and migration. We have recently reported the cellular localization of netrin-4 and its receptor neogenin in human first trimester and term placenta. A strong expression of netrin-4 was observed in trophoblast and in endothelial cells, suggesting a potential role of this protein in placental angiogenesis. In relation to human pregnancy, it has been reported that circulating netrin-4 were increased in fetal umbilical cord blood of intrauterine growth restriction IUGR compared to normal pregnancy suggesting an adverse effect of this protein on placental and fetal development. The aim of this study was to determine the role of netrin-4 in placental angiogenesis.

METHODS

The effects of netrin-4 on proliferation, migration, tube-like organization, and spheroid sprouting of human placental microvascular endothelial cells (HPEC) were studied.

RESULTS

We demonstrated that netrin-4 inhibits HPEC proliferation, tube-like formation, migration and spheroid sprouting, suggesting a direct role of netrin-4 in the regulation of intra-villus angiogenesis.

DISCUSSION

This is the first report of an anti-angiogenic activity of netrin-4 in human placenta. This study brings new insights into netrin-4 roles in placental angiogenesis and suggests possible involvements of netrin-4 in angiogenesis-related pathologies such as IUGR.

Rac1 Regulates Endometrial Secretory Function to Control Placental Development

During placenta development, a succession of complex molecular and cellular interactions between the maternal endometrium and the developing embryo ensures reproductive success. The precise mechanisms regulating this maternal-fetal crosstalk remain unknown. Our study revealed that the expression of Rac1, a member of the Rho family of GTPases, is markedly elevated in mouse decidua on days 7 and 8 of gestation. To investigate its function in the uterus, we created mice bearing a conditional deletion of the Rac1 gene in uterine stromal cells. Ablation of Rac1 did not affect the formation of the decidua but led to fetal loss in mid gestation accompanied by extensive hemorrhage. To gain insights into the molecular pathways affected by the loss of Rac1, we performed gene expression profiling which revealed that Rac1 signaling regulates the expression of Rab27b, another GTPase that plays a key role in targeting vesicular trafficking. Consequently, the Rac1-null decidual cells failed to secrete vascular endothelial growth factor A, which is a critical regulator of decidual angiogenesis, and insulin-like growth factor binding protein 4, which regulates the bioavailability of insulin-like growth factors that promote proliferation and differentiation of trophoblast cell lineages in the ectoplacental cone. The lack of secretion of these key factors by Rac1-null decidua gave rise to impaired angiogenesis and dysregulated proliferation of trophoblast cells, which in turn results in overexpansion of the trophoblast giant cell lineage and disorganized placenta development. Further experiments revealed that RAC1, the human ortholog of Rac1, regulates the secretory activity of human endometrial stromal cells during decidualization, supporting the concept that this signaling G protein plays a central and conserved role in controlling endometrial secretory function. This study provides unique insights into the molecular mechanisms regulating endometrial secretions that mediate stromal-endothelial and stromal-trophoblast crosstalk critical for placenta development and establishment of pregnancy.

During early pregnancy, a succession of molecular interactions between the uterus and the developing embryo ensures reproductive success. Although it is conceivable that signaling cues originating in the uterus impact on the developing embryo at the time of placenta establishment, the precise mechanisms regulating the maternal-fetal crosstalk remain unknown. Impaired uterine functions during early pregnancy are likely to contribute to abnormal embryo development and various diseases of pregnancy, such as recurrent miscarriage, preeclampsia, and intrauterine growth restriction. This study provides insights into the molecular mechanisms by which Rac1, a signaling molecule expressed in the decidua, controls uterine secretions that mediate maternal-fetal communication critical for placental development and establishment of pregnancy.

Idiopathic Fetal Growth Restriction: Repercussion of Modulation in Oxidative Stress

Oxidative stress has been proposed as one of the causes involved in idiopathic fetal growth restriction (IFGR). However, the exact relationship between oxidative stress and IFGR is not understood. This study aimed at understanding the role of oxidative stress and antioxidant status in IFGR materno-fetal dyads and matched controls. 75 materno-fetal dyads with IFGR were enrolled with equal number of normal low risk controls. Malondialdehyde (MDA) levels were measured as marker of oxidative stress, while paraoxonase-1 (PON1) activity and total antioxidant capacity (TAC) of serum were measured as markers of antioxidant status. MDA levels were increased in both maternal and cord blood of IFGR neonates as compared to controls (p < 0.001). TAC of serum were found to be decreased in IFGR (both maternal and cord blood) as compared to controls (p < 0.001; p < 0.05, respectively). PON1 activity was found to be decreased in the IFGR mothers while it was found increased in IFGR cord blood (p < 0.01; p < 0.001)). IFGR is a state of increased oxidative stress. Decreased PON1 enzymatic activity in mothers is also associated with IFGR.

Placental adaptations in growth restriction

The placenta is the primary interface between the fetus and mother and plays an important role in maintaining fetal development and growth by facilitating the transfer of substrates and participating in modulating the maternal immune response to prevent immunological rejection of the conceptus. The major substrates required for fetal growth include oxygen, glucose, amino acids and fatty acids, and their transport processes depend on morphological characteristics of the placenta, such as placental size, morphology, blood flow and vascularity. Other factors including insulin-like growth factors, apoptosis, autophagy and glucocorticoid exposure also affect placental growth and substrate transport capacity. Intrauterine growth restriction (IUGR) is often a consequence of insufficiency, and is associated with a high incidence of perinatal morbidity and mortality, as well as increased risk of cardiovascular and metabolic diseases in later life. Several different experimental methods have been used to induce placental insufficiency and IUGR in animal models and a range of factors that regulate placental growth and substrate transport capacity have been demonstrated. While no model system completely recapitulates human IUGR, these animal models allow us to carefully dissect cellular and molecular mechanisms to improve our understanding and facilitate development of therapeutic interventions.

FSH receptor (FSHR) expression in human extragonadal reproductive tissues and the developing placenta, and the impact of its deletion on pregnancy in mice

Expression and function of the follicle-stimulating hormone receptor (FSHR) in females were long thought to be limited to the ovary. Here, however, we identify extragonadal FSHR in both the human female reproductive tract and the placenta, and test its physiological relevance in mice. We show that in nonpregnant women FSHR is present on: endothelial cells of blood vessels in the endometrium, myometrium, and cervix; endometrial glands of the proliferative and secretory endometrium; cervical glands and the cervical stroma; and (at low levels) stromal cells and muscle fibers of the myometrium. In pregnant women, placental FSHR was detected as early as 8-10 wk of gestation and continued through term. It was expressed on: endothelial cells in fetal portions of the placenta and the umbilical cord; epithelial cells of the amnion; decidualized cells surrounding the maternal arteries in the maternal decidua; and the stromal cells and muscle fibers of the myometrium, with particularly strong expression at term. These findings suggest that FSHR expression is upregulated during decidualization and upregulated in myometrium as a function of pregnancy. The presence of FSHR in the placental vasculature suggests a role in placental angiogenesis. Analysis of genetically modified mice in which Fshr is lacking in fetal portions of the placenta revealed adverse effects on fetoplacental development. Our data further demonstrate FSHB and CGA mRNAs in placenta and uterus, consistent with potential local sources of FSH. Collectively, our data suggest heretofore unappreciated roles of extragonadal FSHR in female reproductive physiology.

Analysis of homeobox gene action may reveal novel angiogenic pathways in normal placental vasculature and in clinical pregnancy disorders associated with abnormal placental angiogenesis

Homeobox genes are essential for both the development of the blood and lymphatic vascular systems, as well as for their maintenance in the adult. Homeobox genes comprise an important family of transcription factors, which are characterized by a well conserved DNA binding motif; the homeodomain. The specificity of the homeodomain allows the transcription factor to bind to the promoter regions of batteries of target genes and thereby regulates their expression. Target genes identified for homeodomain proteins have been shown to control fundamental cell processes such as proliferation, differentiation, and apoptosis. We and others have reported that homeobox genes are expressed in the placental vasculature, but our knowledge of their downstream target genes is limited. This review highlights the importance of studying the cellular and molecular mechanisms by which homeobox genes and their downstream targets may regulate important vascular cellular processes such as proliferation, migration, and endothelial tube formation, which are essential for placental vasculogenesis and angiogenesis. A better understanding of the molecular targets of homeobox genes may lead to new therapies for aberrant angiogenesis associated with clinically important pregnancy pathologies, including fetal growth restriction and preeclampsia.

Population-based placental weight ratio distributions

The placental weight ratio (PWR) is a health indicator that reflects the balance between fetal and placental growth. The PWR is defined as the placental weight divided by the birth weight, and it changes across gestation. Its ranges are not well established. We aimed to establish PWR distributions by gestational age and to investigate whether the PWR distributions vary by fetal growth adequacy, small, average, and large for gestational age (SGA, AGA, and LGA). The data came from a hospital based retrospective cohort, using all births at two London, Ontario hospitals in the past 10 years. All women who delivered a live singleton infant between 22 and 42 weeks of gestation were included (n = 41441). Nonparametric quantile regression was used to fit the curves. The results demonstrate decreasing PWR and dispersion, with increasing gestational age. A higher proportion of SGA infants have extreme PWRs than AGA and LGA, especially at lower gestational ages. On average, SGA infants had higher PWRs than AGA and LGA infants. The overall curves offer population standards for use in research studies. The curves stratified by fetal growth adequacy are the first of their kind, and they demonstrate that PWR differs for SGA and LGA infants.

Placental development during early pregnancy in sheep: effects of embryo origin on vascularization

Utero-placental growth and vascular development are critical for pregnancy establishment that may be altered by various factors including assisted reproductive technologies (ART), nutrition, or others, leading to compromised pregnancy. We hypothesized that placental vascularization and expression of angiogenic factors are altered early in pregnancies after transfer of embryos created using selected ART methods. Pregnancies were achieved through natural mating (NAT), or transfer of embryos from NAT (NAT-ET), or IVF or in vitro activation (IVA). Placental tissues were collected on day 22 of pregnancy. In maternal caruncles (CAR), vascular cell proliferation was less (P<0.05) for IVA than other groups. Compared with NAT, density of blood vessels was less (P<0.05) for IVF and IVA in fetal membranes (FM) and for NAT-ET, IVF, and IVA in CAR. In FM, mRNA expression was decreased (P<0.01-0.08) in NAT-ET, IVF, and IVA compared with NAT for vascular endothelial growth factor (VEGF) and its receptor FLT1, placental growth factor (PGF), neuropilin 1 (NP1) and NP2, angiopoietin 1 (ANGPT1) and ANGPT2, endothelial nitric oxide synthase 3 (NOS3), hypoxia-inducible factor 1A (HIF1A), fibroblast growth factor 2 (FGF2), and its receptor FGFR2. In CAR, mRNA expression was decreased (P<0.01-0.05) in NAT-ET, IVF, and IVA compared with NAT for VEGF, FLT1, PGF, ANGPT1, and TEK. Decreased mRNA expression for 12 of 14 angiogenic factors across FM and CAR in NAT-ET, IVF, and IVA pregnancies was associated with reduced placental vascular development, which would lead to poor placental function and compromised fetal and placental growth and development.

Interaction between human placental microvascular endothelial cells and a model of human trophoblasts: effects on growth cycle and angiogenic profile

Abstract Intrauterine growth restriction (IUGR) is a leading cause of perinatal complications, and is commonly associated with reduced placental vasculature. Recent studies demonstrated over-expression of IGF-1 in IUGR animal models maintains placental vasculature. However, the cellular environment of the placental chorionic villous is unknown. The close proximity of trophoblasts and microvascular endothelial cells in vivo alludes to autocrine/paracrine regulation following Ad-HuIGF-1 treatment. We investigated the co-culturing of BeWo Choriocarcinoma and Human Placental Microvascular Endothelial Cells (HPMVECs) on the endothelial angiogenic profile and the effect Ad-HuIGF-1 treatment of one cell has on the other. HPMVECs were isolated from human term placentas and cultured in EGM-2 at 37°C with 5% CO2. BeWo cells were maintained in Ham's F12 nutrient mix with 10% FBS and 1% pen/strep. Co-cultured HPMVECS+BeWo cells were incubated in serum-free control media, Ad-HuIGF-1, or Ad-LacZ at MOI 0 and MOI 100:1 for 48 h. Non-treated cells and mono-cultured cells were compared to co-cultured cells. Angiogenic gene expression and proliferative and apoptotic protein expression were analysed by RT-qPCR and immunocytochemistry, respectively. Statistical analyses was performed using student's t-test with P < 0.05 considered significant. Direct Ad-HuIGF-1 treatment increased HPMVEC proliferation (n = 4) and reduced apoptosis (n = 3). Co-culturing HPMVECs+BeWo cells significantly altered RNA expression of the angiogenic profile compared to mono-cultured HPMVECs (n = 8). Direct Ad-HuIGF-1 treatment significantly increased Ang-1 (n = 4) in BeWo cells. Ad-HuIGF-1 treatment of HPMVECs did not alter the RNA expression of angiogenic factors. Trophoblastic factors may play a key role in placental vascular development and IGF-1 may have an important role in HPMVEC growth.

Placental gene expression patterns of endoglin (CD105) in intrauterine growth restriction

OBJECTIVE

In this study, we describe placental gene expression patterns of endoglin in pregnancies with intrauterine growth restriction (IUGR) compared to normal pregnancies.

METHODS

Placental samples were obtained from 101 pregnancies with IUGR using 140 normal pregnancy cases as control. Gene expression patterns and protein levels of the endoglin were compared between the two groups. For the gene expression analysis real-time PCR was applied, while for the estimation of placental protein level we performed Western analysis.

RESULTS

The placental endoglin gene was significantly overexpressed in the IUGR group versus the control group (Ln2(α): 1.69). The placental endoglin protein level proved to be significantly higher in case of IUGR (endoglin/β-actin ratio: 13.8 ± 2.3) versus the control cases (5.3 ± 1.1). The placental gene expression as well as the protein levels of endoglin showed no significant difference between female and male newborns. Concerning the placental gene expression and protein level, no significant difference was justified between the more (0-5 percentile) and less (5-10 percentile) severe cases of IUGR.

CONCLUSION

Increased placental gene expression of endoglin may result in vascular dysfunction leading to chronic fetal hypoxia, which may induce VEGF-A to stimulate angiogenesis. This can be explained as feed back response to restore fetal placental circulation.

Testosterone alters maternal vascular adaptations: role of the endothelial NO system

Sex steroid hormones estradiol and progesterone play an important role in vascular adaptations during pregnancy. However, little is known about the role of androgens. Plasma testosterone (T) levels are elevated in preeclampsia, mothers with polycystic ovary, and pregnant African American women, who have endothelial dysfunction and develop gestational hypertension. We tested whether increased T alters vascular adaptations during pregnancy and whether these alterations depend on endothelium-derived factors, such as prostacyclin, endothelium-derived hyperpolarizing factor, and NO. Pregnant Sprague Dawley rats were injected with vehicle (n=12) or T propionate [0.5 mg/Kg per day from gestation day 15-19; n=12] to increase plasma T levels 2-fold, similar to that observed in preeclampsia. Telemetric blood pressures and endothelium-dependent vascular reactivity were assessed with wire-myograph system. Phospho-endothelial NO synthase and total endothelial NO synthase were examined in mesenteric arteries. Mean arterial pressures were significantly higher starting from gestation day19 until delivery in T-treated dams. Endothelium-dependent relaxation responses to acetylcholine were significantly lower in mesenteric arteries of T-treated dams (pD(2) [-log EC(50)]=7.05±0.06; E(max)=89.4±1.89) compared with controls (pD(2)=7.38±0.04; E(max)=99.9±0.97). Further assessment of endothelial factors showed NO-mediated relaxations were blunted in T-treated mesenteric arteries (E(max)=42.26±5.95) compared with controls (E(max)=76.49±5.06); however, prostacyclin- and endothelium-derived hyperpolarizing factor-mediated relaxations were unaffected. Relaxation to sodium nitroprusside was unaffected with T-treatment. Phosphorylations of endothelial NO synthase at Ser(1177) were decreased and at Thr(495) increased in T-treated mesenteric arteries without changes in total endothelial NO synthase levels. In conclusion, increased maternal T, at concentrations relevant to abnormal clinical conditions, cause hypertension associated with blunting of NO-mediated vasodilation. T may induce the increased vascular resistance associated with pregnancy-induced hypertension.

The role of homeobox genes in the development of placental insufficiency

Intrauterine growth restriction (IUGR) is an adverse pregnancy outcome associated with significant perinatal and pediatric morbidity and mortality, and an increased risk of chronic disease later in adult life. While a number of maternal, fetal and environmental factors are known causes of IUGR, the majority of IUGR cases are of unknown cause. These IUGR cases are frequently associated with placental insufficiency, possibly as a result of placental maldevelopment. Understanding the molecular mechanisms of abnormal placental development in IUGR associated with placental insufficiency is therefore of increasing importance. Here, we review our understanding of transcriptional control of normal placental development as well as human IUGR associated with placental insufficiency. We also assess the potential for understanding transcriptional control as a means for revealing new molecular targets for the detection, diagnosis and clinical management of IUGR associated with placental insufficiency.