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Biology of Reproduction Feb 2020During pregnancy, there is increased expression of some cytokines at the fetal-maternal interface; and the clarification of their roles in trophoblast-endometrium... (Review)
Review
During pregnancy, there is increased expression of some cytokines at the fetal-maternal interface; and the clarification of their roles in trophoblast-endometrium interactions is crucial to understanding the mechanism of placentation. This review addresses the up-to-date reported mechanisms by which the members of the transforming growth factor beta superfamily regulate trophoblast proliferation, differentiation, and invasion of the decidua, which are the main phases of placentation. The available information shows that these cytokines regulate placentation in somehow a synergistic and an antagonistic manner; and that dysregulation of their levels can lead to aberrant placentation. Nevertheless, prospective studies are needed to reconcile some conflicting reports; and identify some unknown mediators involved in the actions of these cytokines before their detailed mechanistic regulation of human placentation could be fully characterized. The TGF beta superfamily are expressed in the placenta, and regulate the process of placentation through the activation of several signaling pathways.
Topics: Animals; Cytokines; Endometrium; Female; Humans; Placenta; Placentation; Pregnancy; Transforming Growth Factor beta; Trophoblasts
PubMed: 31566220
DOI: 10.1093/biolre/ioz186 -
Placenta Sep 2019The placenta is a complex and poorly understood organ, which serves as the connection between the mother and the developing fetus. Genomic imprinting, defined as a... (Review)
Review
The placenta is a complex and poorly understood organ, which serves as the connection between the mother and the developing fetus. Genomic imprinting, defined as a regulatory process resulting in the expression of a gene in a parent-of-origin-specific manner, plays an important role in fetal development and placental function. Disturbances that occur during the establishment and maintenance of imprinting could compromise the placenta and fetus, and ultimately, offspring health. Assisted Reproductive Technologies (ART) have been widely used to overcome infertility, however experimental studies have shown that ART procedures affect placentation and the expression of imprinted genes. Here we briefly review the role of imprinted genes in placental development and the evidence from mouse and human studies suggesting ART disrupts imprinted gene regulation in the placenta.
Topics: Animals; Epigenesis, Genetic; Female; Fetal Development; Gene Expression Regulation; Genomic Imprinting; Humans; Placenta; Placentation; Pregnancy; Reproductive Techniques, Assisted
PubMed: 30871810
DOI: 10.1016/j.placenta.2019.02.013 -
Reproduction (Cambridge, England) Nov 2019In humans, pregnancy maintenance depends on normal placental formation following trophoblast invasion into the endometrium and vascular remodeling. In the early stages... (Review)
Review
In humans, pregnancy maintenance depends on normal placental formation following trophoblast invasion into the endometrium and vascular remodeling. In the early stages of pregnancy, immune tolerance, inflammatory response and adaptation to hypoxia need to be precisely regulated in the placental microenvironment. Various types of cells, such as trophoblasts, endothelial cells, immune cells, mesenchymal stem cells (MSCs) and adipocytes, induce normal placental development via intercellular interactions through soluble factors. Extracellular vesicles (EVs) are used to diagnose various diseases because their constituents vary depending on the type of cell of origin and pathological characteristics. EV-derived microRNAs (miRNAs) and proteins in the placenta regulate inflammatory responses and the invasion of trophoblasts through intercellular delivery in the placental microenvironment. If the placenta does not adapt to the changed environment during early pregnancy, pregnancy disorders such as pre-eclampsia, preterm birth and gestational diabetes mellitus can occur. Thus, the important roles of EVs during pregnancy and development is fast emerging. This review describes the physiological role of EVs during placentation and their composition in the human placenta. It also suggests the possibility of finding EV markers that can diagnose pregnancy disorders. Furthermore, it describes the properties of EVs that affect pregnancy in livestock.
Topics: Cellular Microenvironment; Endothelial Cells; Extracellular Vesicles; Female; Humans; Immunomodulation; Inflammation; MicroRNAs; Placenta; Placentation; Pre-Eclampsia; Pregnancy; Pregnancy Complications
PubMed: 31247586
DOI: 10.1530/REP-19-0147 -
Biology of Reproduction May 2023With the development of the embryo, the totipotent blastomere undergoes the first lineage decision to the inner cell mass (ICM) and the trophectoderm (TE). The ICM forms... (Review)
Review
With the development of the embryo, the totipotent blastomere undergoes the first lineage decision to the inner cell mass (ICM) and the trophectoderm (TE). The ICM forms the fetus while the TE forms the placenta, which is one of the unique organs in mammals serving as the interface between maternal and fetal bloodstreams. Proper trophoblast lineage differentiation is crucial for correct placental and fetal development, including the TE progenitor self-renewal and its differentiation toward mononuclear cytotrophoblast, which later either develops into invasive extravillous trophoblast, remodeling the uterine vascular, or fuses into multinuclear syncytiotrophoblast, secreting pregnancy-sustaining hormone. Aberrant differentiation and gene expression of trophoblast lineage is associated with severe pregnancy disorders and fetal growth restriction. This review focuses on the early differentiation and key regulatory factors of trophoblast lineage, which have been poorly elucidated. Meanwhile, the recent development of trophoblast stem cells, trophectoderm stem cells, and blastoids derived from pluripotent stem cells bring the accessible model to investigate the profound mystery of embryo implantation and placentation and were also summarized.
Topics: Animals; Pregnancy; Female; Humans; Trophoblasts; Placenta; Placentation; Cell Differentiation; Pluripotent Stem Cells; Gene Expression; Mammals
PubMed: 36892411
DOI: 10.1093/biolre/ioad027 -
Placenta Apr 2015Hormones have an important role in regulating fetal development. They act as environmental signals and integrate tissue growth and differentiation with relation to... (Review)
Review
Hormones have an important role in regulating fetal development. They act as environmental signals and integrate tissue growth and differentiation with relation to nutrient availability. While hormones control the developmental fate of resources available to the fetus, the actual supply of nutrients and oxygen to the fetus depends on the placenta. However, much less is known about the role of hormones in regulating placental development, even though the placenta has a wide range of hormone receptors and produces hormones itself from early in gestation. The placenta is, therefore, exposed to hormones by autocrine, paracrine and endocrine mechanisms throughout its lifespan. It is known to adapt its phenotype in response to environmental cues and fetal demand signals, particularly when there is a disparity between the fetal genetic drive for growth and the nutrient supply. These adaptive responses help to maintain fetal growth during adverse conditions and are likely to depend, at least in part, on the hormonal milieu. This review examines the endocrine regulation of placental phenotype with particular emphasis on the glucocorticoid hormones. It focuses on the availability of placental hormone receptors and on the effects of hormones on the morphology, transport capacity and endocrine function of the placenta.
Topics: Animals; Female; Fetal Development; Hormones; Humans; Maternal-Fetal Exchange; Phenotype; Placenta; Placental Hormones; Placentation; Pregnancy; Receptors, Cytoplasmic and Nuclear
PubMed: 25524059
DOI: 10.1016/j.placenta.2014.11.018 -
Frontiers in Immunology 2024The transition from oviparity to viviparity and the establishment of feto-maternal communications introduced the placenta as the major anatomical site to provide... (Review)
Review
The transition from oviparity to viviparity and the establishment of feto-maternal communications introduced the placenta as the major anatomical site to provide nutrients, gases, and hormones to the developing fetus. The placenta has endocrine functions, orchestrates maternal adaptations to pregnancy at different periods of pregnancy, and acts as a selective barrier to minimize exposure of developing fetus to xenobiotics, pathogens, and parasites. Despite the fact that this ancient organ is central for establishment of a normal pregnancy in eutherians, the placenta remains one of the least studied organs. The first step of pregnancy, embryo implantation, is finely regulated by the trophoectoderm, the precursor of all trophoblast cells. There is a bidirectional communication between placenta and endometrium leading to decidualization, a critical step for maintenance of pregnancy. There are three-direction interactions between the placenta, maternal immune cells, and the endometrium for adaptation of endometrial immune system to the allogeneic fetus. While 65% of all systemically expressed human proteins have been found in the placenta tissues, it expresses numerous placenta-specific proteins, whose expression are dramatically changed in gestational diseases and could serve as biomarkers for early detection of gestational diseases. Surprisingly, placentation and carcinogenesis exhibit numerous shared features in metabolism and cell behavior, proteins and molecular signatures, signaling pathways, and tissue microenvironment, which proposes the concept of "cancer as ectopic trophoblastic cells". By extensive researches in this novel field, a handful of cancer biomarkers has been discovered. This review paper, which has been inspired in part by our extensive experiences during the past couple of years, highlights new aspects of placental functions with emphasis on its immunomodulatory role in establishment of a successful pregnancy and on a potential link between placentation and carcinogenesis.
Topics: Humans; Pregnancy; Female; Placenta; Animals; Placentation; Endometrium; Neoplasms; Embryo Implantation
PubMed: 38707901
DOI: 10.3389/fimmu.2024.1385762 -
Frontiers in Endocrinology 2022Human placenta secretes a variety of hormones, some of them in large amounts. Their effects on maternal physiology, including the immune system, are poorly understood.... (Review)
Review
Human placenta secretes a variety of hormones, some of them in large amounts. Their effects on maternal physiology, including the immune system, are poorly understood. Not one of the protein hormones specific to human placenta occurs outside primates. Instead, laboratory and domesticated species have their own sets of placental hormones. There are nonetheless several examples of convergent evolution. Thus, horse and human have chorionic gonadotrophins with similar functions whilst pregnancy-specific glycoproteins have evolved in primates, rodents, horses, and some bats, perhaps to support invasive placentation. Placental lactogens occur in rodents and ruminants as well as primates though evolved through duplication of different genes and with functions that only partially overlap. There are also placental hormones, such as the pregnancy-associated glycoproteins of ruminants, that have no equivalent in human gestation. This review focusses on the evolution of placental hormones involved in recognition and maintenance of pregnancy, in maternal adaptations to pregnancy and lactation, and in facilitating immune tolerance of the fetal semiallograft. The contention is that knowledge gained from laboratory and domesticated mammals can translate to a better understanding of human placental endocrinology, but only if viewed in an evolutionary context.
Topics: Animals; Female; Glycoproteins; Horses; Humans; Models, Animal; Placenta; Placental Hormones; Placentation; Pregnancy; Rodentia
PubMed: 35692413
DOI: 10.3389/fendo.2022.891927 -
Theriogenology Jul 2016The gross anatomic features (cotyledonary type) and histologic classification (synepitheliochorial) of the bovine placenta have been known for many years. Thorough... (Review)
Review
The gross anatomic features (cotyledonary type) and histologic classification (synepitheliochorial) of the bovine placenta have been known for many years. Thorough ultrastructural analysis as well as a variety of descriptive studies dealing with the localization of cytoskeletal filaments, extracellular matrix, growth factor systems, steroid hormone receptors, and major histocompatibility complex have contributed further significant knowledge. However, this knowledge was not sufficient to solve clinical placenta-based problems, such as retained fetal membranes. Owing to the complexity of the fetomaternal interface in vitro, culture systems have been developed. As trophoblast giant cells (TGC) are thought to be key players in the cattle placenta, most cell culture models attempt to overcome the pitfall of losing the entire TGC population in vitro. Nevertheless, distinct cell line-based in vitro systems such as cell monolayers or 3-dimensional (co-culture) spheroids were generated for the fetal (trophoblast) and maternal (uterine epithelium) placental compartments. Monolayers have been used to study for example, growth factor or hormonal signaling and TGC formation, whereas spheroids served as models for, for example, trophoblast attachment, uterine epithelium depolarization, and also TGC formation. In the future, the use of more improved culture models might lead to better treatments of retained fetal membranes and increased prevention of embryonic loss. In addition, the in vitro models could shed more light on the mechanisms of the differentiation of uninucleate trophoblast into TGC.
Topics: Animals; Cattle; Female; Placenta; Placentation; Pregnancy; Pregnancy, Animal
PubMed: 27155733
DOI: 10.1016/j.theriogenology.2016.04.043 -
Clinical Obstetrics and Gynecology Sep 2017Abnormalities in placental location or adherence can have important consequences on pregnancy outcome for both mother and fetus. Accurate antenatal detection is crucial... (Review)
Review
Abnormalities in placental location or adherence can have important consequences on pregnancy outcome for both mother and fetus. Accurate antenatal detection is crucial for delivery timing and planning to help reduce perinatal risks for adverse events. We review the relevant literature and present a practical approach for the prenatal detection of abnormal placentation.
Topics: Female; Fetus; Humans; Placenta; Placentation; Pregnancy; Pregnancy Outcome; Prenatal Diagnosis
PubMed: 28742593
DOI: 10.1097/GRF.0000000000000297 -
Reproduction (Cambridge, England) Feb 2022Pregnancy-specific glycoproteins (PSGs) are members of the immunoglobulin superfamily and are closely related to the predominantly membrane-bound CEACAM proteins. PSGs... (Review)
Review
Pregnancy-specific glycoproteins (PSGs) are members of the immunoglobulin superfamily and are closely related to the predominantly membrane-bound CEACAM proteins. PSGs are produced by placental trophoblasts and secreted into the maternal bloodstream at high levels where they may regulate maternal immune and vascular functions through receptor binding and modulation of cytokine and chemokine expression and activity. PSGs may have autocrine and paracrine functions in the placental bed, and PSGs can activate soluble and extracellular matrix bound TGF-β, with potentially diverse effects on multiple cell types. PSGs are also found at high levels in the maternal circulation, at least in human, where they may have endocrine functions. In a non-reproductive context, PSGs are expressed in the gastrointestinal tract and their deregulation may be associated with colorectal cancer and other diseases. Like many placental hormones, PSGs are encoded by multigene families and they have an unusual phylogenetic distribution, being found predominantly in species with hemochorial placentation, with the notable exception of the horse in which PSG-like proteins are expressed in the endometrial cups of the epitheliochorial placenta. The evolution and expansion of PSG gene families appear to be a highly active process, with significant changes in gene numbers and protein domain structures in different mammalian lineages and reports of extensive copy number variation at the human locus. Against this apparent diversification, the available evidence indicates extensive conservation of PSG functions in multiple species. These observations are consistent with maternal-fetal conflict underpinning the evolution of PSGs.
Topics: Animals; DNA Copy Number Variations; Female; Glycoproteins; Horses; Mammals; Phylogeny; Placenta; Placentation; Pregnancy; Trophoblasts
PubMed: 35007205
DOI: 10.1530/REP-21-0390