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Primary hepatic mixed germ cell tumor (GCT) is very rare, and less than 10 cases have been reported. We report a case of mixed GCT composed of a choriocarcinoma and yolk sac tumor, which occurred in the liver of a 40-year-old woman. A large mass was detected by computed tomography solely in the liver. Serum β-human chorionic gonadotropin (hCG) was highly elevated, otherwise, other serum tumor markers were slightly elevated or within normal limits. For hepatic choriocarcinoma, neoadjuvant chemotherapy was administered, followed by right lobectomy. Histologic features of the resected tumor revealed characteristic choriocarcinoma features with diffuse positivity for hCG in the syncytiotrophoblasts and diffuse positivity for α-fetoprotein and Sal-like protein 4 in the yolk sac tumor components. Primary malignant GCT in the liver is associated with a poor prognosis and requires specific treatment. Therefore, GCT should be considered during a differential diagnosis of a rapidly growing mass in the liver.

Objective: 3D optical coherence tomography (OCT) is used for analyses of human placenta organoids in situ without sample preparation. Methods: The trophoblast organoids analyzed were derived from primary human trophoblast. In this study a custom made ultra-high-resolution spectral domain OCT system with uniform spatial and axial resolution of 2.48 μm in organoid tissue was used. The obtained OCT results align to differentiation status tested via quantitative polymerase chain reaction, Western blot analyses, immunohistochemistry, and immunofluorescence of histological sections. Results: 3D OCT enables a more detailed placenta organoid monitoring compared to brightfield microscopy. Inner architecture with light scattering “bridges” surrounding cavities were visualized and quantified in situ for the first time. The formation of these bridges and cavities is congruent to differentiated trophoblast organoids having developed syncytiotrophoblasts. Conclusion: Using 3D OCT in living placenta organoids is a fast tool to assess the differentiation status and resolve internal structures in situ , which is not possible with standard live cell imaging modality. Significance: Only recently human placenta-derived organoids were established, allowing to have a highly reproducible and stable in vitro model to investigate not only developmental but also physiological and pathophysiological processes during early pregnancy. To our knowledge, this work is the first to analyze living human placenta organoids using 3D OCT. Thereby, the rapid and especially non-endpoint OCT qualitative analyses align to the differentiation stage of organoids, which will aid future advancement in this field.

Fragile X-related protein 1 (FXR1) is an RNA-binding protein that can regulate specific mRNA decay in cells. Our previous study showed that FXR1 expression was significantly decreased in trophoblasts from patients with unexplained recurrent spontaneous abortion (RSA); however, the role of FXR1 in trophoblast function during early placenta development has not been fully elucidated. In this study, we found that knockdown of FXR1 using siRNA effectively inhibited the migration of HTR-8 cells and extravillous trophoblast (EVT) outgrowth in an ex vivo extravillous explant culture model. Furthermore, through analysis of a panel of cytokines, we found that the GDF-15 protein was upregulated after knockdown of FXR1 in HTR-8/SVneo cells. This was further confirmed by western blotting and immunofluorescence in HTR-8/SVneo cells and an extravillous explant. Our data also showed that FXR1 expression was downregulated and GDF-15 was upregulated in chorionic villous tissues from RSA patients compared with those from healthy controls (HCs). Further, immunohistochemistry showed a strong expression of GDF-15 in chorionic villous tissue in the RSA group, which was mainly distributed in villous trophoblasts (CTBs) and syncytiotrophoblasts (STBs). Moreover, knockdown of GDF-15 enhanced the migration of HTR-8 cells, while overexpression of GDF-15 using plasmid or treatment with recombinant human GDF-15 protein inhibited trophoblast migration. Importantly, RNA-binding protein immunoprecipitation showed that FXR1 directly bound to the 3′-UTR of GDF-15 mRNA to promote GDF-15 mRNA decay. Together, our data provide new insight into the function of FXR1 in human placenta via regulation of GDF-15 expression in trophoblasts and suggest a possible pathological process involved in RSA.

Cytotrophoblasts differentiate in two directions during early placentation: syncytiotrophoblasts (STBs) and extravillous trophoblasts (EVTs). STBs face maternal immune cells in placentas, and EVTs, which invade the decidua and uterine myometrium, face the cells in the uterus. This situation, in which trophoblasts come into contact with maternal immune cells, is known as the maternal-fetal interface. Despite fetuses and fetus-derived trophoblast cells being of the semi-allogeneic conceptus, fetuses and placentas are not rejected by the maternal immune system because of maternal-fetal tolerance. The acquired tolerance develops during normal placentation, resulting in normal fetal development in humans. In this review, we introduce placental development from the viewpoint of molecular biology. In addition, we discuss how the disruption of placental development could lead to complications in pregnancy, such as hypertensive disorder of pregnancy, fetal growth restriction, or miscarriage.

BackgroundPregnant women and developing fetuses comprise a particularly vulnerable population as multiple studies have shown associations between prenatal air pollution exposure and adverse pregnancy outcomes. However, the mechanisms underlying the observed developmental toxicity are mostly unknown, in particular, if pollution particles can cross the human placenta to reach the fetal circulation.ResultsHere, we investigated the accumulation and translocation of diesel exhaust particles (DEPs), as a model particle for combustion-derived pollution, in human perfused placentae using label-free detection by femtosecond pulsed laser illumination. The results do not reveal a significant particle transfer across term placentae within 6 h of perfusion. However, DEPs accumulate in placental tissue, especially in the syncytiotrophoblast layer that mediates a wealth of essential functions to support and maintain a successful pregnancy. Furthermore, DEPs are found in placental macrophages and fetal endothelial cells, showing that some particles can overcome the syncytiotrophoblasts to reach the fetal capillaries. Few particles are also observed inside fetal microvessels.ConclusionsOverall, we show that DEPs accumulate in key cell types of the placental tissue and can cross the human placenta, although in limited amounts. These findings are crucial for risk assessment and protection of pregnant women and highlight the urgent need for further research on the direct and indirect placenta-mediated developmental toxicity of ambient particulates. This work received fnancial support from the Flemish Scientifc Research Foundation (Grant no 1150920N, G082317N, and 12P6819N) and the Swiss National Science Foundation (Grant no 31003A_179337 and IZSEZ0_193948). The detection equipment was funded by the Interuniversity Attraction Poles Program (P7/05) initiated by the Belgian Science Policy Ofce and the INCALO project (ERC-PoC). Acknowledgements The authors would like to acknowledge all participants of the study. In addition, we owe special thanks to the nurses, midwives, and doctors involved in placenta collection. The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Immune activation at the maternal-fetal interface is a main pathogenic factor of preeclampsia (PE). Neutrophils (PMNs) are activated in PE patients, but the mechanism and consequences of PMN activation need to be further explored. Here, we demonstrated that interleukin-32 (IL-32) expression was significantly upregulated in syncytiotrophoblasts (STBs) and that IL-32β was the major isoform with increased expression in the placenta of severe PE (sPE) patients. Furthermore, the level of IL-32 expression in the placenta was correlated with its level in the serum of sPE patients, indicating that IL-32 in the serum is derived mainly from the placenta. Then, in vitro experiments showed that IL-32β could highly activate PMNs and that these IL-32β-activated PMNs were better able to adhere to endothelial cells (HUVECs) and enhance the expression of vascular cell adhesion molecule-1 (VCAM-1) and intercellular cell adhesion molecule-1 (ICAM-1) in HUVECs, which could be reversed by preincubation with the NADPH oxidase inhibitor VAS 2870. In addition, we showed that IL-32β mainly activated PMNs by binding to proteinase 3. Finally, IL-32β administration induced a PE-like phenotype in a pregnant mouse model. This study provides evidence of the involvement of IL-32β in the pathogenesis of PE.

Depletion of hepatocyte growth factor (HGF) or mesenchymal-epithelial transition factor (c-Met) in mice leads to fetal lethality and placental maldevelopment. However, the dynamic change pattern of HGF/c-Met signaling during placental development and its involvement in the early differentiation of trophoblasts remain to be elucidated. In this study, using in situ hybridization assay, we elaborately demonstrated the spatial-temporal expression of Hgf and c-Met in mouse placenta from E5.5, the very early stage after embryonic implantation, to E12.5, when the placental structure is well developed. The concentration of the soluble form of c-Met (sMet) in maternal circulation peaked at E10.5. By utilizing the induced differentiation model of mouse trophoblast stem cells (mTSCs), we found that HGF significantly promoted mTSC differentiation into syncytiotrophoblasts (STBs) and invasive parietal trophoblast giant cells (PTGCs). Interestingly, sMet efficiently reversed the effect of HGF on mTSC differentiation. These findings indicate that HGF/c-Met signaling participates in regulating placental trophoblast cell fate at the early differentiation stage and that sMet acts as an endogenous antagonist in this aspect.

Introduction Syncytiotrophoblasts are the major components of the human placenta involved in fetal maternal exchange and hormone secretion. The syncytiotrophoblasts arise from the fusion of villous cytotrophoblasts. The cell cycle suppressor p57KIP2 is known to be an essential molecule for proper trophoblast differentiation during placental formation. Methods We generated p57KIP2-expressing BeWo transfectant cells. Proliferation assay and matrigel invasion assay were used to characterize p57KIP2-expressing BeWo transfectant cells. To reveal the role of p57KIP2 in syncytialization, we proceeded syncytium formation analysis and qRT-PCR for detection of the expression levels Syncytin-1, Syncytin-2 and their receptors. Results The human choriocarcinoma cell line, BeWo has undetectable levels of p57KIP2 expression. Expression of p57KIP2 reduced cell proliferation rate and extracellular matrix invasion activity. p57KIP2 expressing cells displayed multinucleated cells associated with syncytiotrophoblast differentiation. In the syncytialization event, p57KIP2 was found to potentiate forskolin-induced upregulation of Syncytin-2 in a cAMP-independent manner. Discussion These results indicate that the expression of p57KIP2 may act on the proliferation/invasion inhibitory factor and enhance the expression of Syncytin-2, which are associated with syncytialization in cytotrophoblasts.

The placenta is a transient but important multifunctional organ crucial for healthy pregnancy for both mother and fetus. Nevertheless, limited access to human placenta samples and the paucity of a proper in vitro model system has hampered our understanding of the mechanisms underlying early human placental development and placenta-associated pregnancy complications. To overcome these constraints, we established a simple procedure with a short-term treatment of bone morphogenetic protein 4 (BMP4) in trophoblast stem cell culture medium (TSCM) to convert human primed pluripotent stem cells (PSCs) to trophoblast stem-like cells (TSLCs). These TSLCs show not only comparable morphology and global gene expression profiles to bona fide human trophoblast stem cells (TSCs) but also long-term self-renewal capacity with bipotency that allows the cells to differentiate into functional extravillous trophoblasts (EVT) and syncytiotrophoblasts (ST). These indicate that TSLCs are equivalent to genuine human TSCs. Our data suggest a straightforward approach to make human TSCs directly from pre-existing primed PSCs and provide a valuable opportunity to study human placenta development and pathology even from patients with placenta-related diseases.HIGHLIGHTSShort-term treatment of BMP4 in TSCM induces human primed PSCs into TSLCsTSLCs possess similar self-renewal and bipotency as bona fide TSCsGlobal gene expression profiling shows high similarity between TSLCs and TSCsTSLC-derived EVT and ST possess characteristics shown in TSC-derived counterparts

Nonhuman primates are excellent models for studying human placentation as experimental manipulations in vitro can be translated to in vivo pregnancy. Our objective was to develop macaque trophoblast stem cells (TSCs) as an in vitro platform for future assessment of primate trophoblast development and function. Macaque TSC lines were generated by isolating first and second trimester placental villous cytotrophoblasts followed by culture in TSC medium to maintain cellular proliferation. TSCs grew as mononuclear colonies, whereas upon induction of syncytiotrophoblast (ST) differentiation multinuclear structures appeared, indicative of syncytium formation. Chorionic gonadotropin secretion was > 4000-fold higher in ST culture media compared to TSC media. The secretion of chorionic gonadotropin by TSC-derived ST reflects a reprogramming of macaque TSCs to an earlier pregnancy phenotype. Characteristic trophoblast hallmarks were defined in TSCs and ST including expression of C19MC miRNAs and the macaque placental nonclassical MHC class I molecule, Mamu-AG. Extravillous trophoblasts (EVTs) were derived that express macaque EVT markers Mamu-AG and CD56, and also secrete high levels of MMP2. Our analyses of macaque TSCs suggests that these cells represent a proliferative, self-renewing population capable of differentiating to STs and EVTs in vitro thereby establishing an experimental model of primate placentation.

Objective The aim of the current review is to present a systematic evaluation of reported human placental findings in cases of zika virus (ZIKV) infection. Data sources We reviewed the EMBASE, PUBMED, and SCIELO databases until June 2019, without language restrictions. Selection of studies The search terms placenta AND zika virus were used. The inclusion criteria of the studies were studies that reported placental findings in humans. Experimental studies, reviews, notes or editorials were excluded. A total of 436 studies were retrieved; after duplicate exclusion, 243 articles had their titles screened, and 128 had their abstract read; of those, 32 were included in the final analysis (18 case reports, 10 case series, and 4 cohorts) Data collection We collected data concerning the author, year of publication, study design, number of participants, number of placental samples, onset of symptoms, perinatal outcomes, and main findings on histological analysis. Data synthesis The placental pathologic findings were described as mild and nonspecific, similar to those of other placental infections, including chronic placentitis, chronic villitis, increased Hofbauer cells, irregular fibrin deposits, increased mononuclear cells in the villus stroma, villous immaturity, edema, hypervascularization, stromal fibrosis, calcification, and focal necrosis of syncytiotrophoblasts. Conclusion Zika infection presents unspecific placental findings, similar to other infections in the toxoplasmosis, other agents, rubella, cytomegalovirus, and herpes (TORCH)group. Characterizing and standardizing placental findings after zika virus infection is key to understanding the mechanisms of congenital diseases. Resumo Objetivo O objetivo desta revisão é apresentar uma avaliação sistemática dos achados relacionados à infecção por zika vírus (ZIKV) na placenta humana. Fontes de dados As bases de dados EMBASE, PUBMED, e SCIELO foram pesquisadas, até junho de 2019, sem qualquer restrição de língua. Seleção dos estudos Os termos placenta E zika virus foram utilizados na busca. Foram incluídos estudos que reportassem achados placentários de infecção em seres humanos, enquanto estudos experimentais, revisões, notas e editoriais foram excluídos. Um total de 436 estudos foram identificados, e 243 tiveram seus títulos lidos após a exclusão de duplicatas. Cento e vinte e oito artigos tiveram seus resumos avaliados, dos quais 32 foram incluídos na análise final (18 relatos de caso, 10 séries de casos, e 4 estudos de coorte). Dados obtidos Foram pesquisados dados relativos ao autor, ano da publicação, desenho do estudo, número de participantes, número de amostras de placenta, início dos sintomas, desfechos perinatais, e principais achados histológicos. Síntese dos dados Os principais achados placentários descritos foram leves e inespecíficos, similares a outras infecções placentárias, incluindo infecção placentária crônica, vilosite crônica, aumento das células de Hofbauer, depósitos irregulares de fibrina, aumento das células mononucleares no estroma viloso, imaturidade vilosa, edema, hipervascularização, fibrose estromal, calcificação, e necrose focal dos sincicitrofoblastos. Conclusão Infecções por ZIKV têm achados placentários inespecíficos, similares aos de outras infecções do grupo toxoplasmose, rubéola, citomegalovírus e herpes (TORCH). Caracterizar e padronizar os achados placentários após infecção por ZIKV é fundamental para entender o mecanismo das infecções congênitas.

Preeclampsia, a major human pregnancy-specific disorder, leads to maternal and fetal morbidity and mortality. Here we reported that 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), an enzyme that degrades active glucocorticoids, is one of the key factors that contributes to preeclampsia development. In the pregnant rat model, we firstly confirmed that administration of 11β-HSD2 inhibitor carbenoxolone (CBX) subcutaneously or by placenta-targeted delivery system could lead to a decrease in placental 11β-HSD2 expression and activity and an increase in corticosterone level in placenta and maternal circulation. Then, we showed that subcutaneous administration and placenta-targeted delivery of CBX resulted in the hallmark of preeclampsia-like features including hypertension, proteinuria, renal damages as well as elevated circulatory soluble fms-like tyrosine kinase 1 (sFlt1) and increased sFlt1/placental growth factor (PlGF) ratio in pregnant rats. These animals displayed decreased trophoblast invasion in uterus, impaired spiral artery remodeling, and reduced placental blood flow. Preeclampsia-like features could also be induced by administration of dexamethasone in pregnant rats. In the cultured human trophoblast models, we found that cortisol only inhibited migration and invasion of the extravillous trophoblasts with 11β-HSD2 knockdown, and promoted sFlt1 release in the cultured syncytiotrophoblasts with 11β-HSD2 knockdown. Furthermore, we elucidated that cortisol stimulated a disintegrin and metalloprotease (ADAM)17 expression in placentas, thereby promoting sFlt1 release in placenta. Collectively, our study provided the evidence that placental 11β-HSD2 dysfunction plays a key role in the development of preeclampsia and immediately identified innovative target to counteract preeclampsia.

Context Crosstalk through receptor ligand interactions at the maternal-fetal interface is impacted by fetal sex. This affects placentation in the first trimester and differences in outcomes. Sexually dimorphic signaling at early stages of placentation are not defined. Objective Investigate the impact of fetal sex on maternal-fetal crosstalk. Design Receptors/ligands at the maternal-fetal surface were identified from sexually dimorphic genes between fetal sexes in the first trimester placenta and defined in each cell type using single-cell RNA-Sequencing (scRNA-Seq). Setting Academic institution. Samples Late first trimester (~10-13 weeks) placenta (fetal) and decidua (maternal) from uncomplicated ongoing pregnancies. Main outcome measures Transcriptomic profiling at tissue and single-cell level; immunohistochemistry of select proteins. Results We identified 91 sexually dimorphic receptor-ligand pairs across the maternal-fetal interface. We examined fetal sex differences in 5 major cell types (trophoblasts, stromal cells, Hofbauer cells, antigen-presenting cells, and endothelial cells). Ligands from the CC family chemokine ligand (CCL) family were most highly representative in females, with their receptors present on the maternal surface. Sexually dimorphic trophoblast transcripts, Mucin-15 (MUC15) and notum, palmitoleoyl-protein carboxylesterase (NOTUM) were also most highly expressed in syncytiotrophoblasts and extra-villous trophoblasts respectively. Gene Ontology (GO) analysis using sexually dimorphic genes in individual cell types identified cytokine mediated signaling pathways to be most representative in female trophoblasts. Upstream analysis demonstrated TGFB1 and estradiol to affect all cell types, but dihydrotestosterone, produced by the male fetus, was an upstream regulator most significant for the trophoblast population. Conclusions Maternal-fetal crosstalk exhibits sexual dimorphism during placentation early in gestation.

Chorionic syncytiotrophoblasts (STB) function as an essential regulator of feto-maternal exchange. Therefore, STB actively differentiate to maintain their continuity for barrier function. However, the placental pathology reported in disorders such as pre-eclampsia (PE) threaten the homeostatic differentiation of STB. Since, HIV-1 requires the expression of co-receptors on STB to undergo vertical transmission, the aim of this study was to determine the effect of PE and HIV infection on the different stages of STB maturation [mature (H2A+) versus differentiating (H2A-)] and to immuno-localize and quantify the expression of histone 2A (H2A) i.e., positive (H2A+) and H2A negative (H2A-) nuclei within placental conducting and exchange villi. We also compared the expression of H2A + and H2A- nuclei between normotensive versus PE groups, HIV status and across the study population.Placental tissue was obtained from pregnant normotensive (n = 30) and pre-eclamptic (n = 30) women after informed written consent. The study groups were further categorized by their HIV status. Immunohistochemistry using the anti-histone 2A (H2A) antibody to identify fully differentiated functional (mature) STB was performed using conventional techniques. Morphometric image analysis was utilized to quantify placental histone H2A immuno-expression in placental exchange and conducting villi. Statistical analysis was performed using GraphPad Prism software.H2A + and H2A- nuclei were immuno-localized within STB of the exchange and conducting villi with H2A- nuclei prominent on the periphery. In the exchange villi, the immuno-expression of H2A + and H2A- nuclei were lower in the PE group compared to the normotensive group (p = 0.0003 and p 0.0001 respectively). A reduced immuno-expression of H2A+ and H2A- nuclei was lower in exchange villi of HIV+ compared to HIV- placentae (p = 0.0002 and p = 0.0276 respectively).PE and HIV reduces the percentage of H2A + and H2A- immuno-expression indicative of mature STB and actively differentiating STB respectively. We speculate that the different maturation states of STB and their orientation resultant of PE pathogenesis may be protective against the process of HIV-1 vertical transmission.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection causing coronavirus disease 2019 (COVID-19) has caused a global health crisis. The primary site of infection is in the respiratory tract but the virus has been associated with a variety of complications involving the gastrointestinal and cardiovascular systems. Since the virus affects a variety of tissue types, there has been interest in understanding SARS-CoV-2 infection in early development and the placenta. ACE2 and TMPRSS2, two genes that are critical for SARS-CoV-2 virus entry are expressed in placenta-specific cell types including extravillous trophoblasts (EVTs) and especially, syncytiotrophoblasts (STs). The potential of SARS-CoV-2 to infect these placental cells and its effect on placental development and function is still unclear. Furthermore, it is crucial to understand the possible mechanism of vertical transmission of SARS-CoV-2 through the placenta. Here, we developed an in vitro model of SARS-CoV-2 infection of placental cell types using induced trophoblast stem cells (iTSCs). This model allowed us to show that STs but not EVTs are infected. Importantly, infected STs lack the expression of key differentiation genes, lack typically observed differentiated morphology and produce significantly lower human chorionic gonadotropin (HCG) compared to non-infected controls. We also show that an anti-ACE2 antibody prevents SARS-CoV-2 infection and restores normal ST differentiation and function. We highlight the establishment of a platform to study SARS-CoV-2 infection in early placental cell types, which will facilitate investigation of antiviral therapy to protect the placenta during early pregnancy and development.

Zika virus (ZIKV) infection at the maternal-placental interface is associated with adverse pregnancy outcomes including fetal demise and pregnancy loss. To determine how infection impacts placental trophoblasts, we utilized rhesus macaque trophoblast stem cells (TSC) that can be differentiated into early gestation syncytiotrophoblasts (ST) and extravillous trophoblasts (EVT). TSCs and STs, but not EVTs, were highly permissive to productive infection with ZIKV strain DAK AR 41524. The impact of ZIKV on the cellular transcriptome showed that infection of TSCs and STs increased expression of immune related genes, including those involved in type I and type III interferon responses. ZIKV exposure altered extracellular vesicle (EV) protein, mRNA, and miRNA cargo, regardless of productive infection. These findings suggest that early gestation macaque TSCs and STs are permissive to ZIKV infection, and that EV analysis may provide a foundation for identifying non-invasive biomarkers of placental infection in a highly translational model.

The human placenta is of vital importance for proper nutrient and waste exchange, immune regulation, and overall fetal health and growth. Specifically, the extracellular matrix (ECM) of placental syncytiotrophoblasts, which extends outward from the placental chorionic villi into maternal blood, acts on a molecular level to regulate and maintain this barrier. Importantly, placental barrier dysfunction has been linked to diseases of pregnancy such as preeclampsia and intrauterine growth restriction. To help facilitate our understanding of the interface and develop therapeutics to repair or prevent dysfunction of the placental barrier, in vitro models of the placental ECM would be of great value. In this study, we aimed to characterize the ECM of an in vitro model of the placental barrier using syncytialized BeWo choriocarcinoma cells. Syncytialization caused a marked change in syndecans, integral proteoglycans of the ECM, which matched observations of in vivo placental ECM. Syndecan-1 expression increased greatly and predominated the other variants. Barrier function of the ECM, as measured by electric cell-substrate impedance sensing (ECIS), increased significantly during and after syncytialization, whereas the ability of THP-1 monocytes to adhere to syncytialized BeWos was greatly reduced compared with nonsyncytialized controls. Furthermore, ECIS measurements indicated that ECM degradation with matrix metalloproteinase-9 (MMP-9), but not heparanase, decreased barrier function. This decrease in ECIS-measured barrier function was not associated with any changes in THP-1 adherence to syncytialized BeWos treated with heparanase or MMP-9. Thus, syncytialization of BeWos provides a physiologically accurate placental ECM with a barrier function matching that seen in vivo.

Oxygen levels in the placental microenvironment throughout gestation are not constant, with severe hypoxic conditions present during the first trimester. This hypoxic phase overlaps with the most critical stages of placental development, i.e., blastocyst implantation, cytotrophoblast invasion, and spiral artery remodeling initiation. Dysregulation of any of these steps in early gestation can result in pregnancy loss and/or adverse pregnancy outcomes. Hypoxia has been shown to regulate not only the self-renewal, proliferation, and differentiation of trophoblast stem cells and progenitor cells, but also the recruitment, phenotype, and function of maternal immune cells. In this review, we will summarize how oxygen levels in early placental development determine the survival, fate, and function of several important cell types, e.g., trophoblast stem cells, extravillous trophoblasts, syncytiotrophoblasts, uterine natural killer cells, Hofbauer cells, and decidual macrophages. We will also discuss the cellular mechanisms used to cope with low oxygen tensions, such as the induction of hypoxia-inducible factor (HIF) or mammalian target of rapamycin (mTOR) signals, regulation of the metabolic pathway, and adaptation to autophagy. Understanding the beneficial roles of hypoxia in early placental development will provide insights into the root cause(s) of some pregnancy disorders, such as spontaneous abortion, preeclampsia, and intrauterine growth restriction.

Background: Fetal growth is determined by the interaction between mother and fetus using the placental interface throughout the pregnancy. Objective: To research apoptosis and appearance of hepatocyte growth factor (HGF) in placentas of different gestational ages and to describe the anthropometrical and clinical indices of mothers and newborns. Materials and Methods: The study material was obtained from 53 human immunodeficiency virus negative pregnant women of legal age without systemic diseases. The staining of placental apoptotic cells was processed by a standard in situ cell death detection kit. The detection of HGF was provided by the ImmunoCruz goat ABC Staining System protocol sc-2023. Relative distribution of positive structures was evaluated using the semiquantitative counting method. Results: The mean rank value of the amount of HGF-containing cells (cytotrophoblasts, syncytiotrophoblasts, extravillous trophoblasts, Höfbauer cells, and cells of extraembryonic mesoderm) was 1.61 ± 0.94. Apoptotic cells (cytotrophoblasts, syncytiotrophoblasts, extravillous trophoblasts, and cells of extraembryonic mesoderm) were found in all placental samples of various gestational ages (term 13.00 ± 13.05 and preterm 27.00 ± 18.25); in general, their amount decreased with advancing gestational age of the placenta (p < 0.01). Conclusion: Weight of a placenta directly depends on the gestational age and correlates with the main fetal anthropometrical parameters (weight, length, and head and chest circumferences). The decrease in HGF-containing and apoptotic cells with advancing gestation depends on the adaptation potential of the placenta, proving the other ways of cellular disposition. Key words: Pregnancy, Placenta, Gestational age, Apoptosis, Immunohistochemistry.

Objective Decorin is a leucine-rich proteoglycan, affects the proliferation, migration, and invasion of extravillous trophoblasts (EVTs). In this study, we aimed to determine the localization of decorin in the implantation site in human tubal ectopic pregnancy, to compare decorin expression levels in ectopic and intrauterine pregnancy, and to investigate the relationship between implantation depth of the tubal wall and expression levels of decorin. Methods 15 patients underwent salpingectomy for tubal ectopic pregnancy and 15 underwent curettage for voluntary interruption of pregnancy were included. All blocks were stained with decorin immunohistochemical staining. Trophoblastic cells of tubal Stage I-III and tubal epithelial and stromal cells were analyzed in terms of presence and intensity of decorin staining. Results Decorin was expressed in both tubal and intrauterine trophoblasts, stroma, and surface epithelium during the first trimester of pregnancy. Decorin staining intensity was significantly lower in the villous cytotrophoblasts and syncytiotrophoblasts in tubal ectopic pregnancies, compared to intrauterine pregnancies (p = 0.001 for both). Decorin staining intensity also significantly lower in the extravillous cytotrophoblasts and syncytiotrophoblasts in the tubal ectopic pregnancies (p = 0.002 and p = 0.001, respectively). There was no significant difference in the staining intensity of the trophoblasts and surface epithelial between Stage II and Stage III tubal invasion; however, the decorin expression was lower in the stroma in Stage III (p = 0.094). Conclusion Decorin expression is significantly lower in trophoblastic cells of tubal ectopic pregnancies than the intrauterine pregnancies. Although it remains limited to explain the underlying cellular mechanisms, decorin seems to play a role in the development of tubal pregnancy.

Study question Does S100P involve in the regulation of lipid metabolism in trophoblast syncytialization during the early stage of pregnancy? Summary answer S100P suppressed lipid droplets overloading in trophoblast syncytialization during the early stage of pregnancy. What is known already S100P is a 95-amino acid protein belongs to the large family of S100 calcium-binding proteins and is exclusively expressed in syncytiotrophoblast layer of placenta, enhancing trophoblast cells proliferation, motility and invasion. Recent studies indicated S100P was aberrantly expressed in various malignant tumors, promoting their proliferation, survival, the formation and invasion of vessels, and has a close relationship with their grade malignancy, hormone dependency and the drug-resistance. Syncytialization is trophoblast cells differentiated from cytotrophoblasts fused into multinucleated cell clusters with cell boundaries deficiency. Study design, size, duration Tissues were collected from elective first trimester pregnancy terminations of healthy people and patients with recurrent spontaneous abortion. Human trophoblast stem cells (hTSCs) were isolated from Week 6 to Week 8 of fresh placental tissues (n = 8) and use forskolin to induce syncytialization. Participants/materials, setting, methods Tissues were collected from elective first trimester surgical pregnancy terminations to determine localization, abundance and function of S100P. The level of S100P protein and gene was measured by Real-time quantitative PCR (RT-qPCR), western blot, ELISA and immunofluorescence in hTSC induced ST(2D)-TSCT. The lipid droplets were assessed by Oil red O stain, BODIPY and electron microscope. Serum S100P concentration in normal and recurrent miscarriage patients were measured by ELISA. Main results and the role of chance S100P was exclusively localized in syncytiotrophoblast layer of the placental villous from gestational weeks 6–8 (n = 4); S100p serum concentration was increased markedly as the gestation progressed (n = 40, p Limitations, reasons for caution The role of S100P on placenta lacks the evidence from animal models. Wider implications of the findings: S100P is an important factor facilitating in trophoblast syncytialization in the first trimester of pregnancy and could be a biomarker of the early pregnancy sustenance. Trial registration number Not applicable

Placental infection by SARS-CoV-2 with various pathologic alterations reported. Inflammatory findings, such as extensive perivillous fibrin deposition and intervillous histiocytosis, have been postulated as risk factors for fetal infection by SARS-CoV-2. We describe the placental findings in a case of a 31-year-old mother with SARS-CoV-2 infection who delivered a preterm female neonate who tested negative for SAR-CoV2 infection. Placental examination demonstrated a small for gestational age placenta with extensive intervillous histiocytosis, syncytiotrophoblast karyorrhexis, and diffuse intervillous fibrin deposition. Immunohistochemical staining demonstrated infection of the syncytiotrophoblasts by SARS-CoV-2 inversely related to the presence of intervillous histiocytes and fibrin deposition. Our case demonstrates that despite extensive placental pathology, no fetal transmission of SARS-CoV-2 occurred, as well as postulates a relationship between placental infection, inflammation, and fibrin deposition.

Supplemental Digital Content is available in the text., The protein p57 is encoded by CDKN1C. This gene is known to be paternally imprinted and maternally expressed in cytotrophoblasts and villous stromal cells. We present a method for evaluating p57 antibodies (Abs) in hydatidiform mole (HM) and demonstrate the results for 4 p57 Abs in various cell types. Five cases of complete HM, diploid with 2 paternal genome sets (CHM;PP), 5 cases of partial HM, triploid with 2 paternal and 1 maternal genome sets (PHM;PPM), and 5 cases of non-HM, with diploid biparental genomes (non-HM;PM) were stained with p57 Abs: 57P06, EP183, KP10, and KP39. Assessment of the fraction of nuclei stained, and the intensity of staining of the nuclei and cytoplasm was performed. For evaluation of the Abs, the observations in cytotrophoblasts, villous stromal cells, maternal decidual cells, and intermediate trophoblasts were scored. The fraction of stained nuclei in cytotrophoblasts and villous stromal cells and the staining of cytoplasm showed to be important parameters in the evaluation of the Abs. 57P06 was evaluated as optimal. KP10 showed moderate cytoplasmatic staining in maternal decidual cells and intermediate trophoblasts, and was evaluated as good. EP183 was evaluated as poor, primarily due to nuclear staining in ≥10% of the villous stromal cells in CHM;PP. KP39 was evaluated as poor, primarily due to strong cytoplasmatic staining in some cytotrophoblasts and villous stromal cells. A structured testing of p57 for diagnosing HM is recommended. No nuclear staining was observed in syncytiotrophoblasts of CHM;PP, indicating that in syncytiotrophoblasts also, CDKN1C is paternally imprinted.

Cell fusion is a hallmark of placental trophoblast cell differentiation and the mature syncytiotrophoblasts play essential roles for fetal-maternal exchange and production of pregnancy-related hormones. Using a well-established in vitro trophoblast differentiation model, we performed a microarray analysis on mRNA expression in trophoblast and syncytiotrophoblast cell cultures. Dramatic changes in gene expression patterns were detected during trophoblast differentiation. Real-time PCR analysis confirmed the reliability of the microarray data. As many as 3524 novel and known genes have been found to be up- or down-regulated for >2-fold. A number of cell cycle regulator including CDC6, CDC20, Cyclins B2, L1 and E2, were down-regulated in the syncytiotrophoblast, providing a mechanism for the loss of mitotic activity during trophoblast differentiation. Further characterization on the identified genes may lead to better understanding of placental patho-physiology in obstetric diseases such as preeclampsia.

Summary Extracellular vesicle (EV) exchange is emerging as a novel method of communication at the maternal–fetal interface. The presence of the EVs has been demonstrated in the preimplantation embryo culture medium from different species, such as bovines, porcines and humans. Preimplantation embryo-derived EVs have been shown to carry molecules potentially able to modulate the local endometrial immune system. The non-classical major histocompatibility complex (MHC) class I molecule human leucocyte antigen (HLA)-G, the immunomodulatory molecule progesterone-induced blocking factor and some regulatory miRNAs species are contained in embryo-derived EV cargo. The implanted syncytiotrophoblasts are also well known to secrete EVs, with microvesicles exerting a mainly proinflammatory effect while exosomes in general mediate local immunotolerance. This review focuses on the current knowledge on the potential role of EVs released by the embryo in the first weeks of pregnancy on the maternal immune cells. Collectively, the data warrant further exploration of the dialogue between the mother and the embryo via EVs.

The placenta plays a role in the pathophysiology of preeclampsia. Preeclampsia is more common in multifetal pregnancies than singleton pregnancies. In this study, we aimed to investigate the histopathology of normotensive and preeclamptic placentas and the localization of alkaline phosphatase activity. In our study, 10 normotensive and 10 preeclamptic, totally 20 placentas were obtained.Paraffin sections were stained with Hematoxylin-Eosin, Masson trichrome and PAS for histopathological examination.Remaining sections were then stained via Gomori’s method and micrographed under light microscope. Sections of the control group observed normal histologically structure.The alkaline phosphatase reaction was evident in the inner and outer membranes of the syncytiotrophoblasts. There was a significant increase in the number of syncytial knots, terminal villi and syncytial bridges in the preeclamptic placenta sections. Marked thickening of the trophoblast basal membranes were observed. Alkaline phosphatase reaction in preeclampsia group: The localization of alkaline phosphatase in the inner and outer membranes of the syncytiotrophoblasts was reduced. In placentas of preeclampsia group, a significant increase in syncytial knot, syncytial bridge were observed. The level of alkaline phosphatase enzyme in preeclamptic placentas was found to be lower compared to normotensive placenta.

We investigated the dynamic expression of calcium transporters, TRPV5 and TRPV6, in placenta and bone to determine their role in maternal and fetal calcium balance during gestation. In placenta, TRPV5 was expressed predominantly in syncytiotrophoblasts of the labyrinthine zone, whereas TRPV6 was expressed in spongiotrophoblasts of the junction zone. In bone, the two transporters were found in osteoblasts, osteoclasts, cartilage and bone matrices. During the first half of gestation, TRPV5 and TRPV6 levels in bone were increased on pregnancy day (P) 0.5, then decreased on P3.5 followed by a slight increase on P6.5. During the second half of pregnancy, both the proteins and their mRNAs gradually increased from P9.5 to P15.5-P17.5 in both bone and placenta, followed at parturition by relatively high amounts in placenta, but markedly decreased amounts in bone. The expression pattern is likely related to the fetal and maternal calcium requirement during gestation, which may be regulated by estrogen and other hormones, because the fetal demand for calcium is greatest during the last few days of gestation for rats; maternal calcium metabolism is designed to meet the calcium needs of the fetus during this period. We found that TRPV5 and TRPV6 are involved in calcium transport in the placenta and bone, and therefore play a role in calcium homeostasis during embryonic and fetal development.

Nongestational choriocarcinoma is a rare malignancy in humans with poor prognosis. Naturally occurring choriocarcinoma is also rare in laboratory mice, and no genetic mouse model accurately recapitulates the features of this cancer. Here we report development of a genetically engineered mouse (GEM) model with alterations in Brca2, Trp53, and RB that develops ovarian tumors. Most of the ovarian tumors displayed histological characteristics of nongestational choriocarcinoma of the ovary (NGCO) (47%) with abundant syncytiotrophoblasts and cytotrophoblasts, positive immunolabeling for human chorionic gonadotropin, and positive periodic acid–Schiff reaction. The rest of the ovarian tumors were serous epithelial ovarian carcinoma (SEOC) (26%) or mixed tumors consisting of NGCO and SEOC (26%). We further established syngeneic orthotopic mouse models for NGCO by in vivo passaging of GEM tumors. These metastatic models provide a platform for evaluating new treatment strategies in preclinical studies aimed at improving outcomes in choriocarcinoma patients.

Placental hypoplasia is associated with the pathophysiology of fetal growth restriction and preeclampsia. The placenta consists of differentiated trophoblasts, including cytotrophoblasts, syncytiotrophoblasts, and extravillous trophoblasts. Cytotrophoblasts are thought to have stem-like characteristics and the ability to differentiate into syncytiotrophoblasts and extravillous trophoblasts. However, it is poorly understood whether isolated cytotrophoblasts derived from hypoplastic placentas have specific features compared with those in normal placentas. This study aimed to determine the features of cytotrophoblasts in hypoplastic placentas. Differentially expressed proteins between isolated cytotrophoblasts from hypoplastic placenta with fetal growth restriction and those from the normal placenta were determined by liquid chromatography-tandem mass spectrometry. Among 6,802 proteins, 1,253 and 2,129 proteins were more than 2-fold upregulated and downregulated, respectively. Among them, ENDOU (endonuclease, poly(U) specific), which has high homology with the coronavirus endoribonuclease nonstructural protein 15 (Nsp15), showed a significantly increased expression in cytotrophoblasts from the placenta with fetal growth restriction related to preeclampsia compared with those in normal control placenta. These results provide insight into the pathological mechanisms of placental hypoplasia and additional information on preeclamptic symptoms in cases of SARS-CoV-2 infected placenta, although further investigation is needed.

Cellular receptors in human cytomegalovirus (HCMV) mother to child transmission play an important role in congenital infection. Placental trophoblast cells are a significant cell type in placental development, placental functional processes, and in HCMV transmission. Different cells within the placental floating and chorionic villi present alternate receptors for HCMV cell entry. Syncytiotrophoblasts present neonatal Fc receptors that bind and transport circulating maternal immunoglobulin G across the placental interface which can also be bound to HCMV virions, facilitating viral entry into the placenta and foetal circulation. Cytotrophoblast express HCMV receptors including integrin-α1β1, integrin-αVβ3, epidermal growth factor receptor and platelet-derived growth factor receptor alpha. The latter interacts with HCMV glycoprotein-H, glycoprotein-L and glycoprotein-O (gH/gL/gO) trimers (predominantly in placental fibroblasts) and the gH/gL/pUL128, UL130-UL131A pentameric complex in other placental cell types. The pentameric complex allows viral tropism of placental trophoblasts, endothelial cells, epithelial cells, leukocytes and monocytes. This review outlines HCMV ligands and target receptor proteins in congenital HCMV infection.

In the human placenta, two trophoblast cell layers separate the maternal blood from the villous basement membrane and fetal capillary endothelial cells. The inner layer, which is complete early in pregnancy and later becomes discontinuous, comprises the proliferative mononuclear cytotrophoblasts, which fuse together and differentiate to form the outer layer of multinucleated syncytiotrophoblasts. Because the syncytiotrophoblasts are responsible for key maternal-fetal exchange functions, tight regulation of this differentiation process is critical for the proper development and the functional role of the placenta. The molecular mechanisms regulating the fusion and differentiation of trophoblasts during human pregnancy remain poorly understood. To decipher the interactions of non-coding RNAs (ncRNAs) in this process, we exposed cultured primary human trophoblasts to standard in vitro differentiation conditions or to conditions known to hinder this differentiation process, namely exposure to hypoxia (O2 < 1%) or to the addition of dimethyl sulfoxide (DMSO, 1.5%) to the culture medium. Using next generation sequencing technology, we analyzed the differential expression of trophoblastic lncRNAs, miRNAs, and mRNAs that are concordantly modulated by both hypoxia and DMSO. Additionally, we developed a model to construct a lncRNA-miRNA-mRNA co-expression network and inferred the functions of lncRNAs and miRNAs via indirect gene ontology analysis. This study improves our knowledge of the interactions between ncRNAs and mRNAs during trophoblast differentiation and identifies key biological processes that may be impaired in common gestational diseases, such as fetal growth restriction or preeclampsia.

The mammalian placenta consists of a set of cells to ensure normal placental functions throughout gestation. Dysfunctional placentae are considered as the origin of a series of pregnancy complications. Therefore, it is urgent for detailed information about the molecular recipes of the cell types within the normal placenta. In the past years, gene expression analysis via single-cell RNA-seq (scRNA-seq) offers opportunities to identify new cell types in a variety of organs and tissues. In this study, scRNA-seq was used to explore the cell heterogeneity within the E10.5 mouse placenta and unravel their discrepancies in cell composition and communications. We identified sixteen cell clusters, including some cell clusters that originated from the maternal tissue. Moreover, we traced the developmental trajectories of trophoblasts and Hofbauer-like cells. Further analysis revealed cell connections between the endothelial cells and pericytes, syncytiotrophoblasts, as well as decidual cells. Besides, we highlighted several signaling pathways, such as the EGF, FGF, canonical, and non-canonical WNT signaling pathways, which mediated the potential crosstalk between different cell types within placenta. Our research provides an in-depth understanding of placental development, cellular composition, and communications at the maternal-fetal interface.

AIM To analyze the differential genetic expression and protein localization of thrombomodulin (THBD) and tissue factor (F3) in the placentas of pregnancies affected by preeclampsia. METHODS We assessed the expression of THBD and F3 by immunohistochemistry and real-time polymerase chain reaction (PCR) in placentas from 20 PE cases: 10 early-onset PE placentas, 10 late-onset PE placentas, and 10 control cases (normal pregnancies). RESULTS In cases, we found higher THBD and F3 RNA levels in placental tissue. Protein expression in controls differed from that in late-onset PE placentas, which had lower THBD levels in syncytiotrophoblasts and amniotic cells. Likewise, late-onset PE placentas exhibited comparatively lower F3 expression in the perivillous fibrin. In contrast, early-onset PE had high F3 expression in the subdecidual fibrin. We found no significant differences in the F3/THBD ratio between the groups. CONCLUSION Our study supports evidence that shows the involvement of F3 and THBD in placental disorders. Furthermore, this finding contributes to a better understanding of the physio-pathological role that these molecules may play in the development of this heterogeneous disease.

Objectives To examine the characteristics and distribution of possible severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) target cells in the human trophectoderm (TE) and placenta. Methods Bioinformatics analysis was performed based on published single-cell transcriptomic datasets of early TE and first- and second-trimester human placentae. We conducted the transcriptomic analysis of 4198 early TE cells, 1260 first-trimester placental cells and 189 extravillous trophoblast cells (EVTs) from 24-week placentae (EVT_24W) using the SMART-Seq2 method. In addition, to confirm the bioinformatic results, we performed immunohistochemical staining of three first-trimester, three second-trimester and three third-trimester placentae from nine women recruited prospectively to this study. We evaluated the expression of the SARS-CoV-2-related molecules angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2). Results Via bioinformatic analysis, we identified the existence of ACE2 and TMPRSS2 expression in human TE as well as in first- and second-trimester placentae. In the human TE, 54.4% of TE1 cells, 9.0% of cytotrophoblasts (CTBs), 3.2% of EVTs and 29.5% of syncytiotrophoblasts (STBs) were ACE2-positive. In addition, 90.7% of TE1 cells, 31.5% of CTBs, 22.1% of EVTs and 70.8% of STBs were TMPRSS2-positive. In placental cells, 20.4% of CTBs, 44.1% of STBs, 3.4% of EVTs from 8-week placentae (EVT_8W) and 63% of EVT_24W were ACE2-positive, while 1.6% of CTBs, 26.5% of STBs, 1.9% of EVT_8W and 20.1% of EVT_24W were TMPRSS2-positive. Pathway analysis revealed that EVT_24W cells that were positive for both ACE2 and TMPRSS2 (ACE2 + TMPRSS2-positive) were associated with morphogenesis of branching structure, extracellular matrix interaction, oxygen binding and antioxidant activity. The ACE2 + TMPRSS2-positive TE1 cells were correlated with an increased capacity for viral invasion, epithelial-cell proliferation and cell adhesion. Expression of ACE2 and TMPRSS2 was observed on immunohistochemical staining in first-, second- and third-trimester placentae. Conclusions ACE2- and TMPRSS2-positive cells are present in the human TE and placenta in all three trimesters of pregnancy, which indicates the possibility that SARS-CoV-2 could spread via the placenta and cause intrauterine fetal infection. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Endogenous retroviruses (ERVs) are proviral phases of exogenous retroviruses, which have coevolved with vertebrate genomes for millions of years. The conservation of ERV genes throughout evolution suggests their beneficial effects on their hosts' survival. An example of such positive selection is demonstrated by the syncytin gene, which encodes a protein with affinity for various mammalian placentas that is involved in the formation of syncytiotrophoblasts. Although the horse has an epitheliochorial placenta, in which the fetal trophoblasts are simply apposed to the intact uterine epithelium, we have previously demonstrated that the equine ERV (EqERV) env RNA is unexpectedly expressed in placental tissue. In the present study, we investigated the mRNA expression pattern of the EqERV env gene in different parts of the equine placenta, to gain more insight into its putative role in the fetal–maternal relationship. To this end, we used reverse transcription–quantitative PCR (RT–qPCR) and in situ hybridization assays to analyze different target areas of the equine placenta. The retroviral env gene is expressed in the equine placenta, even though there is no syncytium or erosion of the uterine endometrium. The gene is also expressed in all the sampled areas, although with some quantitative differences. We suggest that these differences are attributable to variations in the density, height, and degree of morphological complexity of the chorionic villi forming the microcotyledons. The involvement of the EqERV env gene in different functional pathways affecting the fetus–mother relationship can be hypothesized.