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: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.

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Activation of the interferon pathway in trophoblast cells infected with SARS-CoV-2

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