Placentation in different mammalian species

HtrA4 is well conserved only in higher primates and functionally important for EVT differentiation

INTRODUCTION

The placenta differs greatly among species, and deep extra-villous trophoblast (EVT) invasion is a unique feature of placentation of higher primates including humans. We reported serine protease HtrA4 being found predominantly in human placentas with aberrant expression linked to preeclampsia. However, it remains unclear where HtrA4 is produced in the placenta, how it is expressed in other species, and whether it is essential for human placentation.

METHODS

We first compared HtrA4 protein sequences of over 100 species, then scrutinized the key characteristics of HtrA4 in the human, rhesus macaque and mouse, and determined cellular localization in the placenta. We next investigated functional significance of HtrA4 in EVT differentiation using human trophoblast stem cells (TSCs).

RESULTS

Across broader species HtrA4 is well conserved only in higher primates. In humans, only the placenta expressed HtrA4, localising to trophoblasts of villous as well as extra-villous lineages. Rhesus macaques produced HtrA4 but again only in placentas, whereas mice showed no abundant HtrA4 expression anywhere including the placenta, yet it was an active protease if produced. The functional importance of HtrA4 in human EVT was demonstrated using TSCs, which expressed low levels of HtrA4 but significantly up-regulated it during EVT differentiation, and knockdown of HtrA4 severely inhibited the differentiation process.

DISCUSSION

HtrA4 is expressed in placentas of humans and macaques but not mice; it is critical for human EVT differentiation. Together with previous reports showing HtrA4 is also indispensable for syncytialization, this study further revealed HtrA4 as a functionally important protease for human placentation.

Distinct properties of putative trophoblast stem cells established from somatic cell nuclear-transferred pig blastocysts

BACKGROUND

Genetically modified pigs are considered ideal models for studying human diseases and potential sources for xenotransplantation research. However, the somatic cell nuclear transfer (SCNT) technique utilized to generate these cloned pig models has low efficiency, and fetal development is limited due to placental abnormalities.

RESULTS

In this study, we unprecedentedly established putative porcine trophoblast stem cells (TSCs) using SCNT and in vitro-fertilized (IVF) blastocysts through the activation of Wing-less/Integrated (Wnt) and epidermal growth factor (EGF) pathways, inhibition of transforming growth factor-β (TGFβ) and Rho-associated protein kinase (ROCK) pathways, and supplementation with ascorbic acid. We also compared the transcripts of putative TSCs originating from SCNT and IVF embryos and their differentiated lineages. A total of 19 porcine TSCs exhibiting typical characteristics were established from SCNT and IVF blastocysts (TSCsNT and TSCsIVF). Compared with the TSCsIVF, TSCsNT showed distinct expression patterns suggesting unique TSCsNT characteristics, including decreased mRNA expression of genes related to apposition, steroid hormone biosynthesis, angiopoiesis, and RNA stability.

CONCLUSION

This study provides valuable information and a powerful model for studying the abnormal development and dysfunction of trophoblasts and placentas in cloned pigs.

Adipokines in pregnancy

Reproductive success consists of a sequential events chronology, starting with the ovum fertilization, implantation of the embryo, placentation, and cellular processes like proliferation, apoptosis, angiogenesis, endocrinology, or metabolic changes, which taken together finally conduct the birth of healthy offspring. Currently, many factors are known that affect the regulation and proper maintenance of pregnancy in humans, domestic animals, or rodents. Among the determinants of reproductive success should be distinguished: the maternal microenvironment, genes, and proteins as well as numerous pregnancy hormones that regulate the most important processes and ensure organism homeostasis. It is well known that white adipose tissue, as the largest endocrine gland in our body, participates in the synthesis and secretion of numerous hormones belonging to the adipokine family, which also may regulate the course of pregnancy. Unfortunately, overweight and obesity lead to the expansion of adipose tissue in the body, and its excess in both women and animals contributes to changes in the synthesis and release of adipokines, which in turn translates into dramatic changes during pregnancy, including those taking place in the organ that is crucial for the proper progress of pregnancy, i.e. the placenta. In this chapter, we are summarizing the current knowledge about levels of adipokines and their role in the placenta, taking into account the physiological and pathological conditions of pregnancy, e.g. gestational diabetes mellitus, preeclampsia, or intrauterine growth restriction in humans, domestic animals, and rodents.

Derivation of human trophoblast stem cells from placentas at birth

Human trophoblast stem cells (hTSCs) have emerged as a powerful tool for modeling the placental cytotrophoblast (CTB) in vitro. hTSCs were originally derived from CTBs of the first trimester placenta or blastocyst-stage embryos in trophoblast stem cell medium (TSCM) that contains epidermal growth factor (EGF), the glycogen synthase kinase-beta (GSK3β) inhibitor CHIR99021, the transforming growth factor-beta (TGFβ) inhibitors A83-01 and SB431542, valproic acid (VPA), and the Rho-associated protein kinase (ROCK) inhibitor Y-27632. Here we show that hTSCs can be derived from CTBs isolated from the term placenta, using TSCM supplemented with a low concentration of mitochondrial pyruvate uptake inhibitor UK5099 and lipid-rich albumin (TUA medium). Notably, hTSCs could not be derived from term CTBs using TSCM alone, or in the absence of either UK5099 or lipid-rich albumin. Strikingly, hTSCs cultured in TUA medium for a few passages could be transitioned into TSCM and cultured thereafter in TSCM. hTSCs from term CTBs cultured in TUA medium as well as those transitioned into and cultured in TSCM thereafter could be differentiated to the extravillous trophoblast and syncytiotrophoblast lineages and exhibited high transcriptome similarity with hTSCs derived from first trimester CTBs. We anticipate that these results will enable facile derivation of hTSCs from normal and pathological placentas at birth with diverse genetic backgrounds and facilitate in vitro mechanistic studies in trophoblast biology.

Livestock species as emerging models for genomic imprinting

Genomic imprinting is an epigenetically-regulated process of central importance in mammalian development and evolution. It involves multiple levels of regulation, with spatio-temporal heterogeneity, leading to the context-dependent and parent-of-origin specific expression of a small fraction of the genome. Genomic imprinting studies have therefore been essential to increase basic knowledge in functional genomics, evolution biology and developmental biology, as well as with regard to potential clinical and agrigenomic perspectives. Here we offer an overview on the contribution of livestock research, which features attractive resources in several respects, for better understanding genomic imprinting and its functional impacts. Given the related broad implications and complexity, we promote the use of such resources for studying genomic imprinting in a holistic and integrative view. We hope this mini-review will draw attention to the relevance of livestock genomic imprinting studies and stimulate research in this area.

Placental-fetal distribution of carbon particles in a pregnant rabbit model after repeated exposure to diluted diesel engine exhaust

BACKGROUND

Airborne pollution particles have been shown to translocate from the mother's lung to the fetal circulation, but their distribution and internal placental-fetal tissue load remain poorly explored. Here, we investigated the placental-fetal load and distribution of diesel engine exhaust particles during gestation under controlled exposure conditions using a pregnant rabbit model. Pregnant dams were exposed by nose-only inhalation to either clean air (controls) or diluted and filtered diesel engine exhaust (1 mg/m³) for 2 h/day, 5 days/week, from gestational day (GD) 3 to GD27. At GD28, placental and fetal tissues (i.e., heart, kidney, liver, lung and gonads) were collected for biometry and to study the presence of carbon particles (CPs) using white light generation by carbonaceous particles under femtosecond pulsed laser illumination.

RESULTS

CPs were detected in the placenta, fetal heart, kidney, liver, lung and gonads in significantly higher amounts in exposed rabbits compared with controls. Through multiple factor analysis, we were able to discriminate the diesel engine exposed pregnant rabbits from the control group taking all variables related to fetoplacental biometry and CP load into consideration. Our findings did not reveal a sex effect, yet a potential interaction effect might be present between exposure and fetal sex.

CONCLUSIONS

The results confirmed the translocation of maternally inhaled CPs from diesel engine exhaust to the placenta which could be detected in fetal organs during late-stage pregnancy. The exposed can be clearly discriminated from the control group with respect to fetoplacental biometry and CP load. The differential particle load in the fetal organs may contribute to the effects on fetoplacental biometry and to the malprogramming of the fetal phenotype with long-term effects later in life.

Correlative multiscale microCT-SBF-SEM imaging of resin-embedded tissue

Three-dimensional biological microscopy presents a trade-off between spatial resolution and field of view. Correlative approaches applying multiple imaging techniques to the same sample can therefore mitigate against these trade-offs. Here, we present a workflow for correlative microscopic X-ray microfocus computed tomography (microCT) and serial block face scanning electron microscopy (SBF-SEM) imaging of resin-embedded tissue, using mammalian placental tissue samples as an example. This correlative X-ray and electron microscopy (CXEM) workflow allows users to image the same sample at multiple resolutions, and target the region of interest (ROI) for SBF-SEM based on microCT. We detail the protocols associated with this workflow and demonstrate its application in multiscale imaging of horse placental villi and ROI selection in the labyrinthine zone of a mouse placenta. These examples demonstrate how the protocol may need to be adapted for tissues with different densities.

Integrated Placental Modelling of Histology with Gene Expression to Identify Functional Impact on Fetal Growth

Fetal growth restriction (FGR) is a leading cause of perinatal morbidity and mortality. Altered placental formation and functional capacity are major contributors to FGR pathogenesis. Relating placental structure to function across the placenta in healthy and FGR pregnancies remains largely unexplored but could improve understanding of placental diseases. We investigated integration of these parameters spatially in the term human placenta using predictive modelling. Systematic sampling was able to overcome heterogeneity in placental morphological and molecular features. Defects in villous development, elevated fibrosis, and reduced expression of growth and functional marker genes (IGF2, VEGA, SLC38A1, and SLC2A3) were seen in age-matched term FGR versus healthy control placentas. Characteristic histopathological changes with specific accompanying molecular signatures could be integrated through computational modelling to predict if the placenta came from a healthy or FGR pregnancy. Our findings yield new insights into the spatial relationship between placental structure and function and the etiology of FGR.

Omics insights into extracellular vesicles in embryo implantation and their therapeutic utility

Implantation success relies on intricate interplay between the developing embryo and the maternal endometrium. Extracellular vesicles (EVs) represent an important player of this intercellular signalling through delivery of functional cargo (proteins and RNAs) that reprogram the target cells protein and RNA landscape. Functionally, the signalling reciprocity of endometrial and embryo EVs regulates the site of implantation, preimplantation embryo development and hatching, antioxidative activity, embryo attachment, trophoblast invasion, arterial remodelling, and immune tolerance. Omics technologies including mass spectrometry have been instrumental in dissecting EV cargo that regulate these processes as well as molecular changes in embryo and endometrium to facilitate implantation. This has also led to discovery of potential cargo in EVs in human uterine fluid (UF) and embryo spent media (ESM) of diagnostic and therapeutic value in implantation success, fertility, and pregnancy outcome. This review discusses the contribution of EVs in functional hallmarks of embryo implantation, and how the integration of various omics technologies is enabling design of EV-based diagnostic and therapeutic platforms in reproductive medicine.

Comparative stereological evaluation of the term allantochorion membrane in the mare pregnant with mule foals and equine foals

Mules are derived from crossing horse mares with a donkey, in which the interest is due to gentleness and ability to work and equestrian sports. As the placenta is responsible for fetal development and maturation, knowing its typical microstructure allows us to understand how fetomaternal interactions occur in this interspecific pregnancy. Thus, the study performed a comparative stereological evaluation of volumetric composition and fetomaternal contact surface in the uterine body (UB), gravid uterine horn (GUH), and nongravid uterine horn (NGUH) of Mangalarga Paulista mare's term allantochorion membrane in mule and equine pregnancies. In equine gestation, the UB microcotyledon surface density was negatively correlated with the NGUH absolute area and the total volume of microvilli. In mule gestation, the base width and the number of microcotyledon were negatively correlated with the height and number of microcotyledons in the NGUH. Mule also showed a negative correlation between (1) the UB microcotyledon surface density and the GUH microcotyledons number per unit of membrane length, (2) the GUH total volume and the NGUH microcotyledon number. Such differences demonstrate a compensatory mechanism in conversion capacity among macrocompartments. A trend toward a greater total volume of allantoid vessels and total volume of allantoid mesoderm in UB microvilli was found in the equine and mule groups, respectively. There was a significant increase in the base width of microcotyledons in the NGUH of mules versus horses. These finds possibly influence the exchange capacity of each placental microregion and suggest a difference between mule versus horse term allantochorion membrane.

Placental glycotype of the caviomorph rodent Lagostomus maximus and its evolution within Eutheria

The main evolutionary milestone in the oviparity-viviparity transition is placentation. The placenta is an organ with great morphological diversity among eutherians. The expression of different glycosidic residues (Gr) in the near-term placenta constitutes its glycotype. In this study, the expression of different Gr was determined by lectin histochemistry in early, midterm, and near-term placentas of the plains viscacha (Lagostomus maximus), a caviomorph rodent with the highest poliovulatory rate and embryonic resorption rate among eutherians. Besides, a matrix with the expression of each Gr in the exchange trophoblast of viscacha and other eutherians was constructed to map and infer phylogenetic and evolutionary relationships. Between early, midterm, and near-term placentas, variations in the pattern expression of Gr were observed. The glycotype of the near-term placenta is composed of a high diversity of Gr. Reconstruction of the ancestral state for each Gr present in the near-term placenta showed a diverse scenario: some sugars were common to the species of Placentalia included in this study. In the analyzed species with synepitheliochorial and epitheliochorial placentas, no differential glycosylation patterns between them were observed. In species with invasive placentas, such as the endotheliochorial placentas of Carnivora, some common Gr were detected among them, while others were species-specific. In species with hemochorial placenta, the same Gr are shared. Particularly, in the viscacha greater differences with species of the Hominidae and even Muridae families were observed. Nevertheless, greater similarities with other caviomorph rodents were detected. Placental glycotype of each species constitutes an excellent tool to achieve phylogenetic and evolutionary inferences among eutherians.

Endometrial extracellular matrix components do not change over the course of embryonic diapause and reactivation in the roe deer (Capreolus capreolus)

The modification of the endometrial extracellular matrix (ECM) is a crucial step for embryo implantation in many mammalian species. The embryo of the European roe deer (Capreolus capreolus) displays a 4-5 months long temporary reduction of developmental pace termed embryonic diapause. A reduction of epithelial cell height during diapause has previously been described. Co-occurring ECM modifications may contribute to the changes of the intra-uterine milieu during reactivation at which the embryo regains developmental velocity. We assessed the localization of five ECM proteins (collagen I and IV, fibronectin, laminin, and extracellular matrix protein 1) using immunohistochemistry in animals with early, late, and post-diapause (elongating) embryos. While our results confirmed the reduction of epithelial height during diapause, we only detected marginal differences in localization and staining intensities of the selected ECM proteins. Major ECM remodelling events in the roe deer endometrium are thus likely to occur only at implantation.

Progesterone Induces Apoptosis and Steroidogenesis in Porcine Placental Trophoblasts

Placentation and placental steroidogenesis are important for pregnancy and maternal−fetal health. As pregnancy progresses, the main site of progesterone (P4) synthesis changes from the corpus luteum to the placenta, in which placental trophoblasts are the main cell type for P4 synthesis. Therefore, this study investigated the effects of P4 on apoptosis and steroidogenesis in porcine placental trophoblasts and the underlying molecular mechanisms. Porcine placental trophoblasts were treated with different concentrations of P4 for 48 h in a serum-free medium in vitro. Cell number, steroidogenesis, and relevant gene and protein expression levels were detected. A high dose of P4 (10.0 μM) significantly increased P4 (p < 0.01), androstenedione (p < 0.05), testosterone (p < 0.05), and estradiol (p < 0.05) production in porcine placental trophoblasts compared with that in control cells, while a low dose of P4 (1 × 10−3 μΜ) had no marked impact on steroid production. The mRNA expression of apoptosis-related genes (CASP3, CASP8, and Bax) (p < 0.05) and steroidogenesis-related genes (CYP11A1, CYP19A1, and StAR) (p < 0.01) was upregulated, and the expression of HSD3B and HSD17B4 was inhibited (p < 0.05) in the porcine placental trophoblasts treated with high doses of P4. Low doses of P4 had a lighter effect on gene expression than high doses. The expression of apoptosis-related proteins CASP3 (p < 0.05), and Bax (p < 0.01) and steroidogenesis-related proteins CYP19A1 (p < 0.05) and StAR (p < 0.01) was raised, but the proliferation-related protein CCND2 (p < 0.01) was downregulated in the pTr cells treated with high dose of P4. In comparison, a low dose of P4 inhibited the expression of Bax, CYP11A1 (all p < 0.01), and CCND2 (p < 0.05), but the expression of CASP3 (p < 0.05) and StAR (p < 0.01) was upregulated. In summary, excessive P4 can induce the apoptosis of porcine placental trophoblasts and lead to abnormal steroidogenesis in the placenta and hormone imbalance.

Reference gene selection in bovine caruncular epithelial cells under pregnancy-associated hormones exposure

Examination of transcriptional regulation occurring during pregnancy establishment and maintenance requires the identification of endogenous reference genes characterized by high expression stability. Since the expression of some reference genes may be modulated by pregnancy-associated hormones, the goal of our study was to identify suitable reference genes unaffected by hormonal treatment. In our study bovine caruncular epithelial cells were subjected to progesterone, estrogen and prostaglandin F_2α treatment. Ten candidate reference genes (ACTR1A, CNOT11, HDAC1, HPRT1, RPL19, RPS9, SDHA, SUZ12, UXT and ZNF131) were evaluated with the use of four approaches (geNorm, NormFinder, BestKeeper, delta Ct). We found that RPS9 and SUZ12 displayed the highest expression stability in the tested material. Moreover, HPRT1 and SDHA were found inappropriate for RT-qPCR data normalization as they demonstrated the highest expression variability out of all candidates analysed. Hence geNorm calculations shown that the use of just two best-performing genes would be sufficient for obtaining reliable results, we propose that RPS9 and SUZ12 be used as suitable endogenous controls in future studies investigating gene expression in normal and compromised pregnancies.

Pregnancy and placental development in horses: an update

Horses have been domesticated by man and historical information mostly associates horses with men. Nowadays, however, horse riding is essentially by women. Women are also very much involved in equine sciences, with a large contribution to the understanding of fetoplacental development. While highlighting the work of female scientists, this review describes the recent advances in equine fetoplacental studies, focusing on data obtained by new generation sequencing and progress on the understanding of the role of placental progesterone metabolites throughout gestation. A second emphasis is made on fetal programming, a currently very active field, where the importance of maternal nutrition, mare management or the use of embryo technologies has been shown to induce long term effects in the offspring that might affect progeny's performance. Finally, new perspectives for the study of equine pregnancy are drawn, that will rely on new methodologies applied to molecular explorations and imaging.

Clinical Trial on the Usefulness of On-Site Evaluation of Canine Fetal Fluids by Reagent Test Strip in Puppies at Elective Caesarean Section

Simple Summary

In veterinary medicine, the availability of an easy tool for the immediate evaluation of biological fluids’ composition on site is desirable and beneficial as a first-line diagnostic instrument in many instances and in several animal species. The aim of the present study was to assess the usefulness of reagent urinary test strips marketed for urines for the on-field evaluation of fetal fluids’ composition in newborn dogs at elective caesarean section. From surviving newborns, a collection of 113 amniotic and 107 allantoic samples was performed, and 8 amniotic and allantoic fluids were collected from non-surviving newborns. All the fetal fluids were assessed by urinary test strips within 5 min from collection. Significant differences were found for both types of fluid between surviving and non-surviving puppies, and between medium/large and small-sized puppies. Differences were also depicted between amniotic and allantoic fluids within the surviving group. These results seem to suggest that the on-site analysis of fetal fluids’ composition by reagent test strips could represent a first-line tool for the evaluation of puppies and for the quick identification of puppies requiring special monitoring and assistance.

Abstract

The reagent urinary test strips (TS) marketed for urines represent the first-line diagnostic tool in many instances. Therefore, the aim of the study was to assess the usefulness of TS for the on-field evaluation of fetal fluids’ composition in newborn dogs at elective caesarean section. Of a total of 137 puppies born at term, 127 survived and 10 did not survive. One hundred and thirteen amniotic and 107 allantoic samples from surviving newborns were collected, and 8 amniotic and allantoic fluids were collected from the non-surviving newborns and assessed by strips. Significantly lower amounts of amniotic glucose and higher amounts of amniotic and allantoic nitrites, amniotic protein, allantoic urobilinogen, and amniotic bilirubin concentrations were found in non-surviving when compared to surviving newborns. In the surviving ones, higher specific gravity and bilirubin concentrations, and lower pH, were found in allantoic than in amniotic fluids. Higher amniotic and allantoic glucose concentrations, higher amniotic and allantoic pH, and lower amniotic and allantoic protein concentrations were found in medium/large- than in small-sized puppies. The TS allowed the quick evaluation of fetal fluids in puppies at birth. The differences between surviving and non-surviving puppies seem to suggest that the on-site analysis of fetal fluids’ composition by TS could represent a first-line diagnostic tool in the field of canine neonatology, allowing the quick recognition of puppies needing assistance as a complementary tool for clinical evaluation.

Insight on Polyunsaturated Fatty Acids in Endometrial Receptivity

Endometrial receptivity plays a crucial role in fertilization as well as pregnancy outcome in patients faced with fertility challenges. The optimization of endometrial receptivity may help with normal implantation of the embryo, and endometrial receptivity may be affected by numerous factors. Recently, the role of lipids in pregnancy has been increasingly recognized. Fatty acids and their metabolites may be involved in all stages of pregnancy and play a role in supporting cell proliferation and development, participating in cell signaling and regulating cell function. Polyunsaturated fatty acids, in particular, are essential fatty acids for the human body that can affect the receptivity of the endometrium through in a variety of methods, such as producing prostaglandins, estrogen and progesterone, among others. Additionally, polyunsaturated fatty acids are also involved in immunity and the regulation of endometrial decidualization. Fatty acids are essential for fetal placental growth and development. The interrelationship of polyunsaturated fatty acids with these substances and how they may affect endometrial receptivity will be reviewed in this article.

Effects of Melatonin Supplementation during Pregnancy on Reproductive Performance, Maternal-Placental-Fetal Redox Status, and Placental Mitochondrial Function in a Sow Model

Melatonin (MT) is a bio-antioxidant that has been widely used to prevent pregnancy complications, such as pre-eclampsia and IUGR during gestation. This experiment evaluated the impacts of dietary MT supplementation during pregnancy on reproductive performance, maternal-placental-fetal redox status, placental inflammatory response, and mitochondrial function, and sought a possible underlying mechanism in the placenta. Sixteen fifth parity sows were divided into two groups and fed each day of the gestation period either a control diet or a diet that was the same but for 36 mg of MT. The results showed that dietary supplementation with MT increased placental weight, while the percentage of piglets born with weight < 900 g decreased. Meanwhile, serum and placental MT levels, maternal-placental-fetal redox status, and placental inflammatory response were increased by MT. In addition, dietary MT markedly increased the mRNA levels of nutrient transporters and antioxidant-related genes involved in the Nrf2/ARE pathway in the placenta. Furthermore, dietary MT significantly increased ATP and NAD+ levels, relative mtDNA content, and the protein expression of Sirt1 in the placenta. These results suggested that MT supplementation during gestation could improve maternal-placental-fetal redox status and reproductive performance by ameliorating placental antioxidant status, inflammatory response, and mitochondrial dysfunction.

The road (not) taken - Placental transfer and interspecies differences

Species differences are among the main reasons for the high failure rate of preclinical studies. A better awareness and understanding of these differences might help to improve the outcome of preclinical research. In reproduction, the placenta is the central organ regulating fetal exposure to a substance circulating in the maternal organism. Exact information about placental transfer can help to better estimate the toxic potential of a substance. From an evolutionary point of view, the chorioallantoic placenta is the organ with the highest anatomical diversity among species. Moreover, frequently used animal models in reproduction belong to rodents and lagomorphs, two groups that are characterized by the generation of an additional type of placenta, which is crucial for fetal development, but absent from humans: the inverted yolk sac placenta. Taken together, the translatability of placental transfer studies from laboratory animals to humans is challenging, which is supported by the fact that numerous species-dependent toxic effects are described in literature. Thus, reliable human-relevant data are frequently lacking and the toxic potential of chemicals and pharmaceuticals for humans can hardly be estimated, often resulting in recommendations that medical treatments or exposure to chemicals should be avoided for safety reasons. Although species differences of placental anatomy have been described frequently and the need for human-relevant research models has been emphasized, analyses of substances with species-dependent placental transfer have been performed only sporadically. Here, we present examples for species-specific placental transfer, including that of nanoparticles and pharmaceuticals, and discuss potential underlying mechanisms. With respect to the COVID 19-pandemic it might be of interest that some antiviral drugs are reported to feature species-specific placental transfer. Further, differences in placental structure and antibody transfer may affect placental transfer of ZIKA virus.

A Potential Role and Contribution of Androgens in Placental Development and Pregnancy

Successful pregnancy requires the establishment of a highly regulated maternal-fetal environment. This is achieved through the harmonious regulation of steroid hormones, which modulate both maternal and fetal physiology, and are critical for pregnancy maintenance. Defects in steroidogenesis and steroid signaling can lead to pregnancy disorders or even fetal loss. The placenta is a multifunctional, transitory organ which develops at the maternal-fetal interface, and supports fetal development through endocrine signaling, the transport of nutrients and gas exchange. The placenta has the ability to adapt to adverse environments, including hormonal variations, trying to support fetal development. However, if placental function is impaired, or its capacity to adapt is exceeded, fetal development will be compromised. The goal of this review is to explore the relevance of androgens and androgen signaling during pregnancy, specifically in placental development and function. Often considered a mere precursor to placental estrogen synthesis, the placenta in fact secretes androgens throughout pregnancy, and not only contains the androgen steroid nuclear receptor, but also non-genomic membrane receptors for androgens, suggesting a role of androgen signaling in placental function. Moreover, a number of pregnancy disorders, including pre-eclampsia, gestational diabetes, intrauterine growth restriction, and polycystic ovarian syndrome, are associated with abnormal androgen levels and androgen signaling. Understanding the role of androgens in the placenta will provide a greater understanding of the pathophysiology of pregnancy disorders associated with androgen elevation and its consequences.

Dopaminergic and serotonergic changes in rabbit fetal brain upon repeated gestational exposure to diesel engine exhaust

Limited studies in humans and in animal models have investigated the neurotoxic risks related to a gestational exposure to diesel exhaust particles (DEP) on the embryonic brain, especially those regarding monoaminergic systems linked to neurocognitive disorders. We previously showed that exposure to DEP alters monoaminergic neurotransmission in fetal olfactory bulbs and modifies tissue morphology along with behavioral consequences at birth in a rabbit model. Given the anatomical and functional connections between olfactory and central brain structures, we further characterized their impacts in brain regions associated with monoaminergic neurotransmission. At gestational day 28 (GD28), fetal rabbit brains were collected from dams exposed by nose-only to either a clean air or filtered DEP for 2 h/day, 5 days/week, from GD3 to GD27. HPLC dosage and histochemical analyses of the main monoaminergic systems, i.e., dopamine (DA), noradrenaline (NA), and serotonin (5-HT) and their metabolites were conducted in microdissected fetal brain regions. DEP exposure increased the level of DA and decreased the dopaminergic metabolites ratios in the prefrontal cortex (PFC), together with sex-specific alterations in the hippocampus (Hp). In addition, HVA level was increased in the temporal cortex (TCx). Serotonin and 5-HIAA levels were decreased in the fetal Hp. However, DEP exposure did not significantly modify NA levels, tyrosine hydroxylase, tryptophan hydroxylase or AChE enzymatic activity in fetal brain. Exposure to DEP during fetal life results in dopaminergic and serotonergic changes in critical brain regions that might lead to detrimental potential short-term neural disturbances as precursors of long-term neurocognitive consequences.

Label-free detection of uptake, accumulation, and translocation of diesel exhaust particles in ex vivo perfused human placenta

Background

Pregnant 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.

Results

Here, 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.

Conclusions

Overall, 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.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-00886-5.

Toxoplasma Effectors that Affect Pregnancy Outcome

As an immune-privileged organ, the placenta can tolerate the introduction of antigens without inducing a strong inflammatory response that would lead to abortion. However, for the control of intracellular pathogens, a strong Th1 response characterized by the production of interferon-γ is needed. Thus, invasion of the placenta by intracellular parasites puts the maternal immune system in a quandary: The proinflammatory response needed to eliminate the pathogen can also lead to abortion. Toxoplasma is a highly successful parasite that causes lifelong chronic infections and is a major cause of abortions in humans and livestock. Here, we discuss how Toxoplasma strain type and parasite effectors influence host cell signaling pathways, and we speculate about how this might affect the outcome of gestation.

A comprehensive review on non-clinical methods to study transfer of medication into breast milk - A contribution from the ConcePTION project

Breastfeeding plays a major role in the health and wellbeing of mother and infant. However, information on the safety of maternal medication during breastfeeding is lacking for most medications. This leads to discontinuation of either breastfeeding or maternal therapy, although many medications are likely to be safe. Since human lactation studies are costly and challenging, validated non-clinical methods would offer an attractive alternative. This review gives an extensive overview of the non-clinical methods (in vitro, in vivo and in silico) to study the transfer of maternal medication into the human breast milk, and subsequent neonatal systemic exposure. Several in vitro models are available, but model characterization, including quantitative medication transport data across the in vitro blood-milk barrier, remains rather limited. Furthermore, animal in vivo models have been used successfully in the past. However, these models don't always mimic human physiology due to species-specific differences. Several efforts have been made to predict medication transfer into the milk based on physicochemical characteristics. However, the role of transporter proteins and several physiological factors (e.g., variable milk lipid content) are not accounted for by these methods. Physiologically-based pharmacokinetic (PBPK) modelling offers a mechanism-oriented strategy with bio-relevance. Recently, lactation PBPK models have been reported for some medications, showing at least the feasibility and value of PBPK modelling to predict transfer of medication into the human milk. However, reliable data as input for PBPK models is often missing. The iterative development of in vitro, animal in vivo and PBPK modelling methods seems to be a promising approach. Human in vitro models will deliver essential data on the transepithelial transport of medication, whereas the combination of animal in vitro and in vivo methods will deliver information to establish accurate in vitro/in vivo extrapolation (IVIVE) algorithms and mechanistic insights. Such a non-clinical platform will be developed and thoroughly evaluated by the Innovative Medicines Initiative ConcePTION.

Evaluation of short-term safety of ultrasound-guided foetal fluid sampling in the dog (Canis lupus familiaris)

BACKGROUND

In humans, analysis of amniotic fluid is widely used for diagnostic and prognostic purposes. Amniocentesis has scarcely been used in veterinary medicine to date, despite a tremendous potential for clinical and research applications in dogs. Our study aimed to establish a safe method for foetal fluid sampling in female dogs.

METHODS

Two transabdominal ultrasound-guided methods were assessed: the "free hand" and the needle-guided bracket sampling. In addition, through a subsequent routinely scheduled ovariohysterectomy, fluid was directly collected. Samples from 98 conceptuses were collected at day 46.7 ± 7.5 of pregnancy.

RESULTS

The amount of fluid retrieved varied between 0.5 and 5.0 ml per collection. Macroscopic examination of the uterus and conceptuses identified 53% of the puncture sites. Neither fluid leakage nor foetal injury was detected, and six hematomas (5.8%) were visible. Ultrasound-guided foetal fluid collection was found to be potentially safe, and it can be performed by using either transabdominal method.

CONCLUSION

Foetal fluid collection is possible with relative ease and low short-term risk, and may open paths for diagnostic, therapeutic and research purposes in dogs. The procedure can provide new insights into prenatal clinical medicine, including diagnostics of foetal deaths, early identification of heritable diseases and so on.

Reproductive immunology in viviparous mammals: evolutionary paradox of interactions among immune mechanisms and autologous or allogeneic gametes and semiallogeneic foetuses

Literally, reproductive immunology was born in bovine on-farm reproduction where seminal experiments intended for developing methods for embryo transfer in cattle were performed. Actually, these experiments led to two of major concepts and fundamental principles of reproductive immunology using the bovine species as a model for biomedical research, namely the concept of acquired immunological tolerance and the paradox of the semiallogeneic bovine foetus whereby such organism can develop within an immunologically competent host. Peter Medawar, a scientist who together with Frank Macfarlande Burnet shared the 1960 Nobel Prize in physiology or medicine for discovery of acquired immunological tolerance, while studying dizygotic cattle twins, thereby giving birth to reproductive immunology. Also, these findings significantly influenced development of organ transplants and showed that using farm animals as models for studying transplantation immunology had general relevance for mammalian biology and health including those of humans. However, the interest for further research of the fascinating maternal immune influences on pregnancy and perinatal outcomes and of the prevention and treatment of immunologically mediated reproductive disorders in viviparous mammals of veterinary relevance by veterinary immunologists and reproductive clinicians have been very scarce regarding the application of nonspecific immunomodulatory agents for prevention and treatment of subfertility and infertility in pigs and cattle, but still broadening knowledge in this area and hold great potential for improving such therapy in the future. The aim of the current overview is to provide up-to-date information and explaining/translating relevant immunology phenomena into veterinary practice for specialists and scientists/clinicians in reproduction of animals.

Influence of N-acetylcysteine on steroidogenesis and gene expression in porcine placental trophoblast cells

N-acetylcysteine (NAC) is a widely used anti-inflammatory agent and antioxidant in vivo and in vitro. As a nutritional supplement, NAC can improve production and reproductive performances in animals through enhancing placental function and regulating hormone production. Trophoblast proliferation and steroid hormone production are two major functions in the placenta. We hypothesized that the effects of NAC on placental function is due to its direct and indirect effects on gene expression in placental trophoblast cells (pTr). To evaluate this hypothesis, we investigated the effects of NAC on steroidogenesis, gene expression, and cell proliferation in porcine pTr in vitro. pTr were treated with NAC in serum-free medium for 24 h with different concentrations (0, 0.1 μM, 1.0 μM, 10.0 μM, 0.1 mM, 1.0 mM, and 10.0 mM). Low-dose NAC (1 μM) stimulated pTr proliferation and decreased progesterone production, while increasing estradiol production (P < 0.05). High-dose NAC (10 mM) suppressed cell proliferation (P < 0.05), but had no effect on steroidogenesis. Low-dose NAC increased CCDN1 and decreased CASP3 and CASP8 mRNA levels (P < 0.05), whereas high-dose NAC decreased CDK4 and CCDN1 and increased CASP3 mRNA levels (P < 0.05). NAC had no effect on the mRNA abundance of StAR and HSD3B. Low-dose NAC upregulated CYP19A1 mRNA expression, and high-dose NAC downregulated CYP11A1 mRNA abundance (P < 0.05). Only low-dose NAC increased NOS3 mRNA abundance and tetrahydrobiopterin reduction (BH4/BH2 ratio). We conclude that NAC may act directly and indirectly on pTr with a dose-dependent manner and may regulate placental function by affecting pTr differentiation via regulating pTr steroid synthesis, cell proliferation, and apoptosis in sows.

Small RNA (sRNA) expression in the chorioallantois, endometrium and serum of mares following experimental induction of placentitis

Intrauterine infection and inflammation remain a major cause of preterm labour in women and mares, with little known about small RNA (sRNA) expression in tissue or circulation. To better characterise placental inflammation (placentitis), we examined sRNA expression in the endometrium, chorioallantois and serum of mares with and without placentitis. Disease was induced in 10 mares via intracervical inoculation of Streptococcus equi ssp. zooepidemicus, either with moderate or high levels of inoculum; three uninoculated gestationally matched mares were used as controls. Matched chorioallantois and endometrium were sampled in two locations: Region 1, gross inflammation near cervical star with placental separation and Region 2, gross inflammation without placental separation. In Region 1, 26 sRNAs were altered in chorioallantois, while 20 were altered in endometrium. Within Region 2, changes were more subdued in both chorioallantois (10 sRNAs) and endometrium (two sRNAs). Within serum, we identified nine significantly altered sRNAs. In summary, we have characterised the expression of sRNA in the chorioallantois, the endometrium and the serum of mares with experimentally induced placentitis using next-generation sequencing, identifying significant changes within each tissue examined. These data should provide valuable information about the physiology of placental inflammation to clinicians and researchers alike.

Effects of N-carbamylglutamate on steroidogenesis and relative abundances of mRNA transcripts in pig placental trophoblasts

Supplementation of N-carbamylglutamate (NCG) improves gestation outcomes, with increased piglet within-litter uniformity of birth weight and reduced peripheral steroid concentrations in pregnant sows and ewes. It was hypothesized that the effect of NCG on placental function results from direct effects on the placental trophoblasts. There, therefore, was investigation of the effects of NCG on pig placental trophoblast (pTr) steroidogenesis, mRNA transcript abundance, and cell proliferation in vitro. The pTr were treated with NCG in serum-free medium for 24-48 h. Treatment with NCG inhibited pTr progesterone, androstenedione, testosterone (all P <  0.01), and estradiol (P <  0.05) production, whereas it promoted (P <  0.05) pTr proliferation. Treatment with NCG suppressed (P <  0.05) the relative abundances of CYP11A1, CYP19A1, and CASP3 and increased abundances of CCDN1 (P <  0.01) and CDK4 (P <  0.05) mRNA transcripts in pTr, whereas NCG treatment had no effect (P >  0.10) on relative abundances of StAR, HSD17B4, or HSD3B mRNA transcripts. Treatments with NCG can increase pTr cell numbers of sows through upregulating CCND1 and CDK4 and suppressing CASP3 mRNA transcript abundances, while modulating steroidogenesis through effects on CYP11A1 and CYP19A1 mRNA transcript abundances. It is concluded that NCG may have a direct action on pTr and may regulate placental function by suppressing pTr differentiation as a consequence of lesser steroid synthesis while promoting pTr proliferation and inhibiting apoptosis in sows.

Placenta specific gene targeting to study histone lysine demethylase and androgen signaling in ruminant placenta

Reproductive efficiency is critically dependent on embryo survival, establishment of a successful pregnancy and placental development. Recent advances in gene editing technology have enabled investigators to use gene knockdown and knockout approaches to better understand the role of hormone signaling in placental function and fetal growth and development. In this review, an overview of ruminant placentation will be provided, including recent data highlighting the role of histone lysine demethylase 1A and androgen signaling in ruminant placenta and pregnancy. Studies in ruminant placenta establish a role for histone lysine demethylase 1A in controlling genetic networks necessary for important cellular events such as cell proliferation and angiogenesis, as well as androgen receptor signaling during early placentation.

Tropism, pathology, and transmission of equine parvovirus-hepatitis

Equine parvovirus-hepatitis (EqPV-H) has recently been associated with cases of Theiler's disease, a form of fulminant hepatic necrosis in horses. To assess whether EqPV-H is the cause of Theiler's disease, we first demonstrated hepatotropism by PCR on tissues from acutely infected horses. We then experimentally inoculated horses with EqPV-H and 8 of 10 horses developed hepatitis. One horse showed clinical signs of liver failure. The onset of hepatitis was temporally associated with seroconversion and a decline in viremia. Liver histology and in situ hybridization showed lymphocytic infiltrates and necrotic EqPV-H-infected hepatocytes. We next investigated potential modes of transmission. Iatrogenic transmission via allogeneic stem cell therapy for orthopedic injuries was previously suggested in a case series of Theiler's disease, and was demonstrated here for the first time. Vertical transmission and mechanical vectoring by horse fly bites could not be demonstrated in this study, potentially due to limited sample size. We found EqPV-H shedding in oral and nasal secretions, and in feces. Importantly, we could demonstrate EqPV-H transmission via oral inoculation with viremic serum. Together, our findings provide additional information that EqPV-H is the likely cause of Theiler's disease and that transmission of EqPV-H occurs via both iatrogenic and natural routes.

Placenta as a target of trichloroethylene toxicity

Trichloroethylene (TCE) is an industrial solvent and a common environmental contaminant detected in thousands of hazardous waste sites. Risk of exposure is a concern for workers in occupations that use TCE as well as for residents who live near industries that use TCE or who live near TCE-contaminated sites. Although renal, hepatic and carcinogenic effects of TCE have been documented, less is known about TCE impacts on reproductive functions despite epidemiology reports associating maternal TCE exposure with adverse pregnancy outcomes. Toxicological evidence suggests that the placenta mediates at least some of the adverse pregnancy outcomes associated with TCE exposure. Toxicology studies show that the TCE metabolite, S-(1,2-dichlorovinyl)-l-cysteine (DCVC) generates toxic effects such as mitochondrial dysfunction, apoptosis, oxidative stress, and release of prostaglandins and pro-inflammatory cytokines in placental cell lines. Each of these mechanisms of toxicity have significant implications for placental functions and, thus, ultimately the health of mother and developing child. Despite these findings there remain significant gaps in our knowledge about effects of TCE on the placenta, including effects on specific placental cell types and functions as well as sex differences in response to TCE exposure. Due to the critical role that the placenta plays in pregnancy, future research addressing some of these knowledge gaps could lead to significant gains in public health.

Non-clinical Models to Determine Drug Passage into Human Breast Milk

BACKGROUND

Successful practice of clinical perinatal pharmacology requires a thorough understanding of the pronounced physiological changes during lactation and how these changes affect various drug disposition processes. In addition, pharmacokinetic processes unique to lactation have remained understudied. Hence, determination of drug disposition mechanisms in lactating women and their babies remains a domain with important knowledge gaps. Indeed, lack of data regarding infant risk during breastfeeding far too often results in discontinuation of breastfeeding and subsequent loss of all the associated benefits to the breastfed infant. In the absence of age-specific toxicity data, human lactation data alone are considered insufficient to rapidly generate the required evidence regarding risks associated with medication use during lactation.

METHODS

Systematic review of literature to summarize state-of-the art non-clinical approaches that have been developed to explore the mechanisms underlying drug milk excretion.

RESULTS

Several studies have reported methods to predict (to some extent) milk drug excretion rates based on physicochemical properties of the compounds. In vitro studies with primary mammary epithelial cells appear excellent approaches to determine transepithelial drug transport rates across the mammary epithelium. Several of these in vitro tools have been characterized in terms of transporter expression and activity as compared to the mammary gland tissue. In addition, with the advent of physiology-based pharmacokinetic (PBPK) modelling, these in vitro transport data may prove instrumental in predicting drug milk concentration time profiles prior to the availability of data from clinical lactation studies. In vivo studies in lactating animals have proven their utility in elucidating the mechanisms underlying drug milk excretion.

CONCLUSION

By combining various non-clinical tools (physicochemistry-based, in vitro and PBPK, in vivo animal) for drug milk excretion, valuable and unique information regarding drug milk concentrations during lactation can be obtained. The recently approved IMI project ConcePTION will address several of the challenges outlined in this review.

The brain-placental axis: Therapeutic and pharmacological relevancy to pregnancy

The placenta plays a critical role in mammalian reproduction. Although it is a transient organ, its function is indispensable to communication between the mother and fetus, and supply of nutrients and oxygen to the growing fetus. During pregnancy, the placenta is vulnerable to various intrinsic and extrinsic conditions which can result in increased risk of fetal neurodevelopmental disorders as well as fetal death. The placenta controls the neuroendocrine secretion in the brain as a means of adaptive processes to safeguard the fetus from adverse programs, to optimize fetal development and other physiological changes necessary for reproductive success. Although a wealth of information is available on neuroendocrine functions in pregnancy, they are largely limited to the regulation of hypothalamus-pituitary-adrenal/gonad (HPA/ HPG) axis, particularly the oxytocin and prolactin system. There is a major gap in knowledge on systems-level functional interaction between the brain and placenta. In this review, we aim to outline the current state of knowledge about the brain-placental axis with description of the functional interactions between the placenta and the maternal and fetal brain. While describing the brain-placental interactions, a special emphasis has been given on the therapeutics and pharmacology of the placental receptors to neuroligands expressed in the brain during gestation. As a key feature of this review, we outline the prospects of integrated pharmacogenomics, single-cell sequencing and organ-on-chip systems to foster priority areas in this field of research. Finally, we remark on the application of precision genomics approaches to study the brain-placental axis in order to accelerate personalized medicine and therapeutics to treat placental and fetal brain disorders.

A Narrative Review of Placental Contribution to Adverse Pregnancy Outcomes in Women With Polycystic Ovary Syndrome

CONTEXT

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy of reproductive-aged women. In pregnancy, women with PCOS experience increased risk of miscarriage, gestational diabetes, preeclampsia, and extremes of fetal birth weight, and their offspring are predisposed to reproductive and cardiometabolic dysfunction in adulthood. Pregnancy complications, adverse fetal outcomes, and developmental programming of long-term health risks are known to have placental origins. These findings highlight the plausibility of placental compromise in pregnancies of women with PCOS.

EVIDENCE SYNTHESIS

A comprehensive PubMed search was performed using terms "polycystic ovary syndrome," "placenta," "developmental programming," "hyperandrogenism," "androgen excess," "insulin resistance," "hyperinsulinemia," "pregnancy," and "pregnancy complications" in both human and animal experimental models.

CONCLUSIONS

There is limited human placental research specific to pregnancy of women with PCOS. Gestational androgen excess and insulin resistance are two clinical hallmarks of PCOS that may contribute to placental dysfunction and underlie the higher rates of maternal-fetal complications observed in pregnancies of women with PCOS. Additional research is needed to prevent adverse maternal and developmental outcomes in women with PCOS and their offspring.

Biological interactions between nanomaterials and placental development and function following oral exposure

We summarize the literature involving the deposition of nanomaterials within the placenta following oral exposure and the biological interactions between nanomaterials and placental development and function. The review focuses on the oral exposure of metal and metal oxide engineered nanomaterials (ENMs), carbon-based ENMs, and nanoplastics in animal models, with a minor discussion of intravenous injections. Although the literature suggests that the placenta is an efficient barrier in preventing nanomaterials from reaching the fetus, nanomaterials that accumulate in the placenta may interfere with its development and function. Furthermore, some studies have demonstrated a decrease in placental weight and association with adverse fetal health outcomes following oral exposure to nanomaterials. Since nanomaterials are increasingly used in food, food packaging, and have been discovered in drinking water, the risk for adverse impacts on placental development and functions, with secondary effects on embryo-fetal development, following unintentional maternal ingestion of nanomaterials requires further investigation.

Placental structure in gestational diabetes mellitus

The placenta is a transitory organ, located between the mother and the foetus, which supports intrauterine life. This organ has nutritional, endocrine and immunologic functions to support foetal development. Several factors are related to the correct functioning of the placenta including foetal and maternal blood flow, appropriate nutrients, expression and function of receptors and transporters, and the morphology of the placenta itself. Placental morphology is crucial for understanding the pathophysiology of the organ as represents the physical structure where nutrient exchange occurs. In pathologies of pregnancy such as diabetes mellitus in humans and animal models, several changes in the placental morphology occur, related mainly with placental size, hypervascularization, higher branching capillaries of the villi and increased glycogen deposits among others. Gestational diabetes mellitus is associated with modifications in the structure of the human placenta including changes in the surface area and volume, as well as histological changes including an increased volume of intervillous space and terminal villi, syncytiotrophoblast number, fibrinoid areas, and glycogen deposits. These modifications may result in functional changes in this organ thus limiting the wellbeing of the developing foetus. This review gives an overview of recurrent morphological changes at macroscopic and histological levels seen in the placenta from gestational diabetes in humans and animal models. This article is part of a Special Issue entitled: Membrane Transporters and Receptors in Pregnancy Metabolic Complications edited by Luis Sobrevia.

Differentiation of derived rabbit trophoblast stem cells under fluid shear stress to mimic the trophoblastic barrier

BACKGROUND

The placenta controls exchanges between the mother and the fetus and therefore fetal development and growth. The maternal environment can lead to disturbance of placental functions, with consequences on the health of the offspring. Since the rabbit placenta is very close to that of humans, rabbit models can provide biomedical data to study human placental function. Yet, to limit the use of animal experiments and to investigate the mechanistic aspects of placental function, we developed a new cell culture model in which rabbit trophoblast cells are differentiated from rabbit trophoblast stem cells.

METHODS

Rabbit trophoblast stems cells were derived from blastocysts and differentiated onto a collagen gel and in the presence of a flow of culture medium to mimic maternal blood flow. Transcriptome analysis was performed on the stem and differentiated cells.

RESULTS

Our culture model allows the differentiation of trophoblast stem cells. In particular, the fluid shear stress enhances microvilli formation on the differentiated cell surface, lipid droplets formation and fusion of cytotrophoblasts into syncytiotrophoblasts. In addition, the transcriptome analysis confirms the early trophoblast identity of the derived stem cells and reveals upregulation of signaling pathways involved in trophoblast differentiation.

CONCLUSION

Thereby, the culture model allows mimicking the in vivo conditions in which maternal blood flow exerts a shear stress on trophoblast cells that influences their phenotype.

GENERAL SIGNIFICANCE

Our culture model can be used to study the differentiation of trophoblast stem cells into cytotrophoblasts and syncytiotrophoblasts, as well as the trophoblast function in physiological and pathological conditions.

Galectin 13 (PP13) Facilitates Remodeling and Structural Stabilization of Maternal Vessels during Pregnancy

Galectins regulate cell growth, proliferation, differentiation, apoptosis, signal transduction, mRNA splicing, and interactions with the extracellular matrix. Here we focus on the galectins in the reproductive system, particularly on a group of six galectins that first appears in anthropoid primates in conjunction with the evolution of highly invasive placentation and long gestation. Of these six, placental protein 13 (PP13, galectin 13) interacts with glycoproteins and glycolipids to enable successful pregnancy. PP13 is related to the development of a major obstetric syndrome, preeclampsia, a life-threatening complication of pregnancy which affects ten million pregnant women globally. Preeclampsia is characterized by hypertension, proteinuria, and organ failure, and is often accompanied by fetal loss and major newborn disabilities. PP13 facilitates the expansion of uterine arteries and veins during pregnancy in an endothelial cell-dependent manner, via the eNOS and prostaglandin signaling pathways. PP13 acts through its carbohydrate recognition domain that binds to sugar residues of extracellular and connective tissue molecules, thus inducing structural stabilization of vessel expansion. Further, decidual PP13 aggregates may serve as a decoy that induces white blood cell apoptosis, contributing to the mother's immune tolerance to pregnancy. Lower first trimester PP13 level is one of the biomarkers to predict the subsequent risk to develop preeclampsia, while its molecular mutations/polymorphisms that are associated with reduced PP13 expression are accompanied by higher rates of preeclampsia We propose a targeted PP13 replenishing therapy to fight preeclampsia in carriers of these mutations.

Placental trophoblast transfer of opioids following exposures to individual or mixtures of opioids in vitro

Infants born with neonatal abstinence syndrome increased 5-fold between 2000 and 2012. Prenatal exposure to opioids has been linked to altered brain development, congenital heart defects, neural tube defects, and clubfoot. In the study presented here, placental transfer rate of six opioids; morphine, heroin, fentanyl, methadone, oxycodone, and naloxone was compared in vitro using a human trophoblast cell monolayer model, BeWo b30. The rate and concentration of opioid translocation were investigated individually and in mixtures. The opioid transfer was quantified at 5, 15, 30, 60, and 120 min, using target liquid chromatography-mass spectrometry. The transfer was lowest for heroin (<1.2% of administered dose at 120 min; the permeability across the cells [P]: 0.21 × 10−5 cm/s) and highest for oxycodone (13.2% of administered dose at 120 min; P: 2.46 × 10−5 cm/s). As oxycodone is a preferred drug for both short- and long-term pain treatment, more knowledge is needed to understand the potential adverse impact on fetal development, growth, and well-being. Opioid exposure is likely to happen as mixtures, and we therefore investigated the transfer of selected mixtures. Permeability was significantly decreased for heroin when administered together with fentanyl. This study demonstrates that the transfer rate between individual opioids varies significantly and that some mixtures may impact the transfer of some individual opioids like heroin.

Impact statement

Gaining knowledge about opioid exposure and placental transfer of opioids is an important part of providing clinicians with the necessary information for therapeutic strategies during pregnancy in the rising opioid epidemic. Opioids exposure often includes a mixture rather than an exposure to an individual opioid. We investigated placental trophoblast permeability to opioids in vitro for six individual opioids and selected mixtures. The rate and concentration of opioid translocation across placental trophoblast monolayer varied considerably between the six investigated opioids. Oxycodone had the highest level of translocation. We also found that the transfer of heroin decreased when administered together with fentanyl, while no change was observed for fentanyl transfer in the mixture. This suggests that opioid mixtures may decrease translocation of some opioids while others are unaffected.

Embryo responses to stress induced by assisted reproductive technologies

Assisted reproductive technology (ART) has led to the birth of millions of babies. In cattle, thousands of embryos are produced annually. However, since the introduction and widespread use of ART, negative effects on embryos and offspring are starting to emerge. Knowledge so far, mostly provided by animal models, indicates that suboptimal conditions during ART can affect embryo viability and quality, and may induce embryonic stress responses. These stress responses take the form of severe gene expression alterations or modifications in critical epigenetic marks established during early developmental stages that can persist after birth. Unfortunately, while developmental plasticity allows the embryo to survive these stressful conditions, such insult may lead to adult health problems and to long-term effects on offspring that could be transmitted to subsequent generations. In this review, we describe how in mice, livestock, and humans, besides affecting the development of the embryo itself, ART stressors may also have significant repercussions on offspring health and physiology. Finally, we argue the case that better control of stressors during ART will help improve embryo quality and offspring health.

Extracellular vesicles generated by placental tissues ex vivo: A transport system for immune mediators and growth factors

PROBLEM

To study the mechanisms of placenta function and the role of extracellular vesicles (EVs) in pregnancy, it is necessary to develop an ex vivo system that retains placental cytoarchitecture and the primary metabolic aspects, in particular the release of EVs and soluble factors. Here, we developed such a system and investigated the pattern of secretion of cytokines, growth factors, and extracellular vesicles by placental villous and amnion tissues ex vivo.

METHODS OF STUDY

Placental villous and amnion explants were cultured for 2 weeks at the air/liquid interface and their morphology and the released cytokines and EVs were analyzed. Cytokines were analyzed with multiplexed bead assays, and individual EVs were analyzed with recently developed techniques that involved EV capture with magnetic nanoparticles coupled to anti-EV antibodies and flow cytometry.

RESULTS

Ex vivo tissues (i) remained viable and preserved their cytoarchitecture; (ii) maintained secretion of cytokines and growth factors; (iii) released EVs of syncytiotrophoblast and amnion epithelial cell origins that contain cytokines and growth factors.

CONCLUSION

A system of ex vivo placental villous and amnion tissues can be used as an adequate model to study placenta metabolic activity in normal and complicated pregnancies, in particular to characterize EVs by their surface markers and by encapsulated proteins. Establishment and benchmarking the placenta ex vivo system may provide new insight in the functional status of this organ in various placental disorders, particularly regarding the release of EVs and cytokines. Such EVs may have a prognostic value for pregnancy complications.

Recent advances in understanding evolution of the placenta: insights from transcriptomics

The mammalian placenta shows an extraordinary degree of variation in gross and fine structure, but this has been difficult to interpret in physiological terms. Transcriptomics offers a path to understanding how structure relates to function. This essay examines how studies of gene transcription can inform us about placental evolution in eutherian and marsupial mammals and more broadly about convergent evolution of viviparity and placentation in vertebrates. Thus far, the focus has been on the chorioallantoic placenta of eutherians at term, the reproductive strategies of eutherians and marsupials, and the decidual response of the uterus at implantation. Future work should address gene expression during early stages of placental development and endeavor to cover all major groups of mammals. Comparative studies across oviparous and viviparous vertebrates have centered on the chorioallantoic membrane and yolk sac. They point to the possibility of defining a set of genes that can be recruited to support commonalities in reproductive strategies. Further advances can be anticipated from single-cell transcriptomics if those techniques are applied to a range of placental structures and in species other than humans and mice.

Global hemostasis in healthy bitches during pregnancy and at different estrous cycle stages: Evaluation of routine hemostatic tests and thromboelastometry

This study assessed the global hemostasis (including prothrombin time [PT], activated partial thromboplastin time [aPTT], antithrombin activity [ATA], fibrinogen and d-Dimer concentrations, platelet count, plateletcrit and thromboelastometry) in healthy pregnant bitches, comparing the results with those of healthy bitches at different estrous cycle stages, and assessed whether hemostatic changes during pregnancy are associated with serum progesterone concentration or the presence of fetuses in utero. The results show that pregnant bitches have higher fibrinogen concentration, platelet count and platelatecrit, and that fibrin and global clot formations occur faster than in non-pregnant bitches at different estrous cycle stages. Additionally, clot strength was higher in pregnant bitches than in non-pregnant ones. There were no differences in PT, ATA, and D-dimer concentration between all study groups. The aPTT was significantly shorter in bitches at the fourth and last pregnancy weeks, compared to the anestrus group, and shorter in both the fourth and last pregnancy weeks groups, compared to diestrus group. These results all support a hypercoagulable state in healthy pregnant bitches, unassociated with progesterone concentration.

Non-invasive evaluation of placental blood flow: lessons from animal models

In human obstetrics, placental vascularisation impairment is frequent as well as linked to severe pathological events (preeclampsia and intrauterine growth restriction), and there is a need for reliable methods allowing non-invasive evaluation of placental blood flow. Uteroplacental vascularisation is complex, and animal models are essential for the technical development and safety assessment of these imaging tools for human clinical use; however, these techniques can also be applied in the veterinary context. This paper reviews how ultrasound-based imaging methods such as 2D and 3D Doppler can provide valuable insight for the exploration of placental blood flow both in humans and animals and how new approaches such as the use of ultrasound contrast agents or ultrafast Doppler may allow to discriminate between maternal (non-pulsatile) and foetal (pulsatile) blood flow in the placenta. Finally, functional magnetic resonance imaging could also be used to evaluate placental blood flow, as indicated by studies in animal models, but its safety in human pregnancy still requires to be confirmed.