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:The mechanisms controlling trophoblast proliferation and differentiation during embryo implantation are fundamentally important in defining a successful pregnancy, yet poorly understood. Human trophoblast stem cells (TSC) and BMP4/A83-01/PD17034-treated pluripotent stem cell derived trophoblast cells (BAP) are two widely employed, contemporary models to study trophoblast development and function but how faithfully they mimic the identity of early stage trophoblast cells has not been fully examined. Here, we evaluate the transcriptomic profiles of trophoblast cells from these two widely used cell models and directly compare them with trophoblast cells from peri-implantation stage human embryos during extended embryo culture (EEC) between embryonic d 8 to d 12. Cells from BAP and TSC models all grouped closely with trophoblast cells from EEC, with the trophoblast sublineages, including cytotrophoblast (CTB), syncytiotrophoblast (STB), and extravillous-like migratory trophoblast (MTB), clustered together following dimensional analysis and unsupervised hierarchical clustering. However, subtle differences amongst models exist for each trophoblast sublineages. TSC-CTB is more similar to EEC-CTB from d 8 embryos with transcripts associated with increased Wnt signaling activities important for trophoblast stemness. BAP-CTB are more similar to EEC-CTB from d 10 and 12 embryos and upregulate transcripts important for trophoblast differentiation and invasion. For STB, EEC-STB showed enriched GO terms related to oxygen-dependent metabolism, while BAP and TSC-derived STB both prioritize lipid and membrane synthesis as well as actin reorganization and cell spreading. EEC-MTB transcripts indicate an increased level of invasiveness and motility compared to TSC-MTB with increased proliferative capacity. We also provide a pool of novel lineage markers in early trophoblast that were upregulated (>4-fold) across all three models and validate the presence of 11 proteins prominent in peri-implantation human embryos. Together, our comprehensive analysis revealed that both commonly used BAP and TSC models resemble features of peri-implantation trophoblasts, while still maintaining subtle transcriptomic differences in sublineages.

Project description:Invasion of cytotrophoblasts into uterine tissues is essential for placental development. To identify molecules regulating trophoblast invasion, mRNA signatures of purified villous (CTB, poor invasiveness) and extravillous (EVT, high invasiveness) trophoblasts isolated from first trimester human placentae and villous explant cultures, respectively, were compared using GeneChip analyses yielding 991 invasion/migration related transcripts. Several genes involved in physiological and pathologic cell invasion, including ADAM-12,-19,-28 as well as Spondin-2, were upregulated in EVT. Pathway prediction analyses identified several functional modules associated with either the invasive or the non-invasive trophoblast phenotype. One of the genes which were downregulated in the invasive mRNA pool, heme oxygenase-1 (HO-1), was selected for functional analyses. Real-time PCR analyses, Western blottting, and immunofluorescene of first trimester placentae and differentiating villous explant cultures demonstrated downregulation of HO-1 in invasive EVT as compared to CTB. Modulation of HO-1 expression in loss-of as well as gain-of function cell models (BeWo and HTR8/SVneo, respectively) demonstrated an inverse relationship of HO-1 expression with trophoblast migration in transwell and wound healing assays. Importantly, HO-1 expression led to an increase in protein levels and activity of the nuclear hormone receptor PPARgamma. Pharmacological inhibition of PPARgamma abrogated the inhibitory effects of HO-1 on trophoblast migration. Collectively, our results demonstrate that gene expression profiling of EVT and CTB can be used to unravel novel regulators of cell invasion. Accordingly, we identify heme oxygenase-1 as a negative regulator of trophoblast motility acting via upregulation of PPARgamma. Experiment Overall Design: To identify genes potentially regulating cell invasion trophoblast cells of early human gestation with distinct invasive properties were profiled. Experiment Overall Design: Distinct gene expression signatures of highly invasive EVT (n = 6) and poorly invasive CTB (n = 5) of different first trimester placentae using Affymetrix U133A GeneChips interrogating >20,000 genes were determined.

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Human pluripotent stem cells as a model of trophoblast differentiation in both normal development and disease

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