Project description:Cytotrophoblast (CTB) are bipotent progenitor epithelial cells of the human placenta, which can differentiate into invasive extravillous trophoblast (EVT) and multinucleated syncytiotrophoblast (STB). Trophoblast stem cells (TSC) have also been shown to be bipotential. In this study, we set out to probe the transcriptional diversity of first trimester CTB and compare TSC to various subgroups of CTB. We performed single-cell RNA sequencing on six normal placentae, four 6-week placentae, two of which were separated into basal and chorionic fractions prior to sequencing, and two 13-week placentae. We also sequenced three TSC lines, derived from 6-8 week placentae, to evaluate similarities and differences between primary CTB and TSC. CTB clusters displayed notable distinctions based on gestational age, with 6-week placentae showing enrichment for specific CTB subtypes, further influenced by origin from the basal or chorionic plate. Differential expression analysis of CTB from basal versus chorionic plate highlighted pathways associated with proliferation, unfolded protein response, and oxidative phosphorylation. We identified trophoblast states representing initial progenitor CTB, precursor STB, precursor and mature EVT, and multiple CTB subtypes. CTB progenitors were enriched at 6-weeks, with basal plate cells biased toward EVT, and chorionic plate cells toward STB, precursors. Clustering and trajectory inference analysis indicated that TSC were most like EVT precursor cells, with only a small percentage of TSC on the pre-STB differentiation trajectory. This was confirmed by flow cytometric analysis of 6 different TSC lines, which showed uniform expression of proximal column markers ITGA2 and ITGA5. Additionally, we found that only ITGA5+ CTB could be plated in 2D, and these cells formed only EVT upon spontaneous differentiation. Our findings suggest that distinct CTB states exist in different regions of the placenta as early as six weeks gestation and that current TSC lines most closely resemble ITGA5+ CTB, biased toward the EVT lineage.

Project description:Trophoblast is the primary epithelial cell type in the placenta, a transient organ required for proper fetal growth and development. We have identified a CDX2+/p63+ cytotrophoblast (CTB) subpopulation in the early post-implantation human placenta, which is significantly reduced later in gestation. CTB differentiate into different trophoblast subtypes, which are responsible for gas/nutrient exchange (syncytiotrophoblast/STB) and invasion and maternal vascular remodeling (extravillous trophoblast/EVT). Study of early human placental development is severely hampered by lack of a representative trophoblast stem cell (TSC) model, with the capacity for self-renewal and the ability to differentiate into both STB and EVT. We describe a reproducible protocol, using defined media containing BMP4, by which human embryonic stem cells (hESC) can be differentiated into CDX2+/p63+ CTB-like cells. These cells can be replated to further differentiate into STB- and EVT-like cells, based on marker expression, hormone secretion and invasive ability. Differentiation of hPSC-derived CTB in hypoxia leads to reduced hCG secretion and STB-associated gene expression, instead inducing EVT differentiation in a hypoxia-inducible factor-dependent manner. Human embryonic stem cells (hESC) (WA09/H9) were maintained on Geltrex-coated plates (BD Biosciences ) in StemPro (Thermo Fisher) + bFGF (12 ng/ml). Undifferentiated hESC (D-2) were switched to minimal media (EMIM (Erb et al., 2011) containing KO DMEM/F12 (Gibco), 1% Insulin-Transferrin-Selenium Mix (Sigma-Aldrich), 1% NEAA (Gibco), 2mM L-Glutamine (Corning), 0.1mM 2-mercaptoethanol (Gibo), and 2% BSA (Gemini Bio Products)) for 2 days then treated with BMP4 (StemRD, 10ng/ml) for 3 days in minimal media+BMP4 (D3). At D3, cells were replated onto Geltrex in Feeder Conditioned Media +BMP4 and cultured in normoxia (20% O2) or hypoxia (2% O2) for 2 days (D3+2) to assess the effect of hypoxia. Cells were infected with lentiviral shRNA for shScramble (control) or shARNT, the beta subunit of the Hypoxia Inducible Factor (HIF) complex to assess the effect of ARNT knockdown. Each sample includes biological triplicates.

Project description:Purpose: Syncytiotrophoblast (STB) is a multi-nucleated, terminally differentiated syncytium that covers the surface of the villous placenta and forms the major interface with maternal blood. It releases placental hormones and plays a primary role in exchange of gases, nutrients and waste products. Alterations in STB development and turnover have been implicated in placental diseases, including preeclampsia (PE). In vitro cell models are badly needed to study STB development and physiology due to inaccessibility to placental tissues during gestation. To establish in vitro STB model system, we generate STB and its mononucleated precursors from human embryonic stem cells (hESC) and profile for RNA content by RNAseq. Methods: H1 Human ESC (WA01) were treated with BMP4, the ALK4/5/7 inhibitor (A83-01), and the FGF2 signaling inhibitor (PD173074) (BAP) to direct them to the trophoblast lineage and provided both STB and extravillous trophoblast. Syncytial areas emerged at day 8 BAP treatment ranged in diameter from ~40 Âµm to > 100 Âµm. The intact syncytial areas were isolated by sieving successively through 70 Î¼m and 40 Î¼m mesh cell strainers. The captured cells are recovered by inverting the strainer and rinsing with culture medium to separate large (>70 Î¼m) and middle size cell sheets (40-70 Î¼m). The fraction that passes through both sieves represents cells of smallest diameter (< 40 Î¼m), presumably cytotrophoblast. Total 12 RNA samples from triplicate three size-fractioned BAP treated and three untreated hESC cultured in a FGF2 supplemented medium in parallel were analyzed. Results: The larger > 70 Î¼m areas stained positively for STB markers while ultrastructural analysis clearly revealed multi-nuclear cells with an extensive cytoplasm containing many prominent secretion granules. The larger STB areas also had a larger DNA content that > 70 Î¼m fraction contained 37 times more nuclear content and 40-70 Âµm fraction did 16 times more. Compared to the < 40 Î¼m cell fraction, these larger cells over-expressed a full repertoire of genes characteristic of STB, e.g. CGA, CGB, PGF, ERVW1, GCM1. The smallest cell fraction had a DNA content consistent with mononuclear diploid cells, contained few secretory granules, and were only weakly positive for STB markers. Conclusion: The data are consistent with the > 70 Î¼m cells being mature STB, while the intermediate fraction may represent a precursor population. Human ESC directed along the trophoblast lineage by BAP treatment offers a useful model for following STB formation in vitro and suggest that this protocol may have utility in studying the basis of certain placental diseases, especially preeclampsia, where placental tissue isolated at term or after pregnancy terminations can only offer limited information. Three size fraction mRNA profiles of syncytial areas emerged at day 8 BAP treatment of hESC were generated by deep sequencing along with untreated hESC, in triplicate, using Illumina HiSeq 2500.

Project description:Purpose: Syncytiotrophoblast (STB) is a multi-nucleated, terminally differentiated syncytium that covers the surface of the villous placenta and forms the major interface with maternal blood. It releases placental hormones and plays a primary role in exchange of gases, nutrients and waste products. Alterations in STB development and turnover have been implicated in placental diseases, including preeclampsia (PE). In vitro cell models are badly needed to study STB development and physiology due to inaccessibility to placental tissues during gestation. To establish in vitro STB model system, we generate STB and its mononucleated precursors from human embryonic stem cells (hESC) and profile for RNA content by RNAseq. Methods: H1 Human ESC (WA01) were treated with BMP4, the ALK4/5/7 inhibitor (A83-01), and the FGF2 signaling inhibitor (PD173074) (BAP) to direct them to the trophoblast lineage and provided both STB and extravillous trophoblast. Syncytial areas emerged at day 8 BAP treatment ranged in diameter from ~40 µm to > 100 µm. The intact syncytial areas were isolated by sieving successively through 70 μm and 40 μm mesh cell strainers. The captured cells are recovered by inverting the strainer and rinsing with culture medium to separate large (>70 μm) and middle size cell sheets (40-70 μm). The fraction that passes through both sieves represents cells of smallest diameter (< 40 μm), presumably cytotrophoblast. Total 12 RNA samples from triplicate three size-fractioned BAP treated and three untreated hESC cultured in a FGF2 supplemented medium in parallel were analyzed. Results: The larger > 70 μm areas stained positively for STB markers while ultrastructural analysis clearly revealed multi-nuclear cells with an extensive cytoplasm containing many prominent secretion granules. The larger STB areas also had a larger DNA content that > 70 μm fraction contained 37 times more nuclear content and 40-70 µm fraction did 16 times more. Compared to the < 40 μm cell fraction, these larger cells over-expressed a full repertoire of genes characteristic of STB, e.g. CGA, CGB, PGF, ERVW1, GCM1. The smallest cell fraction had a DNA content consistent with mononuclear diploid cells, contained few secretory granules, and were only weakly positive for STB markers. Conclusion: The data are consistent with the > 70 μm cells being mature STB, while the intermediate fraction may represent a precursor population. Human ESC directed along the trophoblast lineage by BAP treatment offers a useful model for following STB formation in vitro and suggest that this protocol may have utility in studying the basis of certain placental diseases, especially preeclampsia, where placental tissue isolated at term or after pregnancy terminations can only offer limited information.

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Regenerative trophoblast models are largely in concordance with trophoblasts from peri-implantation human embryos while maintaining subtle differences

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