Project description:Blood and endothelial cells arise from hemangiogenic progenitors that are specified from FLK1-expressing mesoderm by the transcription factor ETV2. FLK1 mesoderm also contributes to other tissues, including vascular smooth muscle (VSM) and cardiomyocytes. However, the developmental process of FLK1 mesoderm generation and its derivatives and the lineage relationship among FLK1 mesoderm derivatives these tissues remain obscure. Recent single cell RNA-sequencing (scRNA-seq) studies of early stages of embryogenesis embryos, or in vitro differentiated human embryonic stem (ES) cells have differentiation provided unprecedented information on the spatiotemporal resolution of cells in embryogenesis. Nonetheless, these snapshots still nonetheless offer insufficient information on dynamic developmental processes due to inadvertently missing intermediate states and unavoidable batch effects. Here we performed scRNA-seq of mouse ES cells in asynchronous embryoid bodies (EBs), in vitro differentiated embryonic stem (ES) cells containing undifferentiated ES cells and its differentiated hemangiogenic progeny, as well as yolk sacs, the first hematopoietic extraembryonic tissue in developing embryo that contains hemangiogenic and VSM lineages. We captured a continuous developmental process from undifferentiated pluripotent cells to FLK1 mesoderm-derived tissues involved in hemangiogenesis. This continuous transcriptome map will benefit both basic and applied studies of mesoderm and its derivatives.
Project description:Investigating the blood, immune and stromal cells present in a human fetal embryo in a world first single cell transcriptomic atlas. The embryo was dissected into 12 coronal sections, yolk sac, and yolk sac stalk. Live single cells sorted, with cell suspension then undergoing 10x chromium 5 prime scRNA-seq. This accession contains the yolk sac and yolk sac stalk data from this embryo. A matched accession contains the coronal section data. Lane "WS_wEMB12142156" (from yolk sac) was excluded from downstream analysis due to low fraction reads in cells post-CellRanger QC. Termination procedure for this embryo was medical. The F158_[features...barcodes...matrix].[tsv...mtx].gz files attached to this accession represent raw count data from all the 10x lanes in this accession combined, and as output from CellRanger filtered matrices (CellRanger version 6.0.1 using human reference genome GRCh38-2020-A). One set of count matrices relates to the yolk sac data, and one set of count matrices relates to the yolk sac stalk data.
Project description:GW182 (Tnrc6a) is a key component of RISC (miRNA-Induced Silencing Complex) that plays a critical role in miRNA-mediated gene silencing. Here, we show that GW182 is expressed in the yolk sac endoderm, and that gene-trap disruption of GW182 leads to growth arrest of yolk sac endoderm, impaired hematopoiesis and embryonic lethality. To investigate roles of GW182 in the yolk sac endoderm, we assessed changes in mRNA expression in the yolk sac of E9.5 GW182gt/gt embryos using microarrays (Affymetrix).
Project description:GW182 (Tnrc6a) is a key component of RISC (miRNA-Induced Silencing Complex) that plays a critical role in miRNA-mediated gene silencing. Here, we show that GW182 is expressed in the yolk sac endoderm, and that gene-trap disruption of GW182 leads to growth arrest of yolk sac endoderm, impaired hematopoiesis and embryonic lethality. To investigate roles of GW182 in the yolk sac endoderm, we assessed changes in mRNA expression in the yolk sac of E9.5 GW182gt/gt embryos using microarrays (Affymetrix). Yolk sac of wild type littermates and GW182gt/gt embryos at E9.5 was collected for total RNA isolation using Trizol (Invitrogen). RNAs were purified according to the manufacturer’s protocol before subjected to Mouse Gene 1.0 ST Whole Genome Array (Affymetrix) for mRNA expression profiling. Experiments were performed in triplicate. Differentially expressed mRNAs were identified using a two-sample t-test (P<0.05 considered significant).
Project description:Genomic imprinting is an epigenetic phenomenon resulting in parent-of-origin mono-allelic expression of a small subset of mammalian genes. Imprinted genes have been categorized into two groups: multi lineage (ML) imprinted genes that can show imprinted expression in both embryonic and extra-embryonic lineages, and genes that show extra-embryonic lineage (EXEL) specific imprinted expression restricted to tissues like the placenta and visceral yolk sac (VYS) endoderm. Many genes showing EXEL imprinted expression are silenced by lncRNAs that act over long distances. Thus the analysis of this form of gene silencing is likely to be pivotal for understanding new mechanisms of long range gene silencing by lncRNAs. It has been reported that ES cells differentiated into cystic embryoid bodies (cystic EBs) contain VYS endoderm and here we investigate if cystic EBs could serve as an in vitro model for the analysis of EXEL imprinted expression. Unexpectedly we found that cystic EBs lack EXEL imprinted expression, while retaining normal imprinted expression of ML genes. This shows that cystic EBs do not model VYS imprinted expression and also argues against previous claims that cystic EBs contain VYS endoderm. We further characterized cystic EBs by performing RNA-seq and whole genome bisulphite sequencing. By comparison to various embryonic tissues we found that cystic EBs more resemble embryonic liver, which contains definitive endoderm, than the extra-embryonic endoderm of the VYS. Examination of gene and retrotranssposone expression and DNA methylation in extraembryonic, embryonic tissues and ES cell diferentiated as cystic EBs
Project description:Genomic imprinting is an epigenetic phenomenon resulting in parent-of-origin mono-allelic expression of a small subset of mammalian genes. Imprinted genes have been categorized into two groups: multi lineage (ML) imprinted genes that can show imprinted expression in both embryonic and extra-embryonic lineages, and genes that show extra-embryonic lineage (EXEL) specific imprinted expression restricted to tissues like the placenta and visceral yolk sac (VYS) endoderm. Many genes showing EXEL imprinted expression are silenced by lncRNAs that act over long distances. Thus the analysis of this form of gene silencing is likely to be pivotal for understanding new mechanisms of long range gene silencing by lncRNAs. It has been reported that ES cells differentiated into cystic embryoid bodies (cystic EBs) contain VYS endoderm and here we investigate if cystic EBs could serve as an in vitro model for the analysis of EXEL imprinted expression. Unexpectedly we found that cystic EBs lack EXEL imprinted expression, while retaining normal imprinted expression of ML genes. This shows that cystic EBs do not model VYS imprinted expression and also argues against previous claims that cystic EBs contain VYS endoderm. We further characterized cystic EBs by performing RNA-seq and whole genome bisulphite sequencing. By comparison to various embryonic tissues we found that cystic EBs more resemble embryonic liver, which contains definitive endoderm, than the extra-embryonic endoderm of the VYS.
Project description:The human yolk sac (YS) is an extra-embryonic tissue critical for early prenatal life development. It is the first site of haematopoiesis where progenitors differentiate from endoderm within blood islands of the yolk sac contributing initially to primitive erythropoiesis and in subsequent waves to erythro-myeloid and lymphoid differentiation.
Project description:Implantation of the human embryo commences a critical developmental stage that comprises profound events including axis formation, gastrulation, and the emergence of yolk sac hematopoietic system. Our mechanistic knowledge of this window of human life remains limited due to restricted access to in vivo samples for both technical and ethical reasons. Stem cell models of human embryo have emerged to help unlock the mysteries of this stage. Here, we present a model of early post-implantation human embryogenesis (embryoid) with an extra-embryonic endoderm and mesoderm niche to support early hematopoiesis. This human embryo model is genetically inducible, and its unanticipated self-organization results in the development of the amniotic cavity, formation of bilaminar disc embryonic morphology, an anterior hypoblast pole and posterior domain. The extra-embryonic layer of iDiscoid presents multilineage yolk sac tissue morphogenesis with extra-embryonic mesoderm and lacks trophoblast. Its development captures distinct waves of yolk sac hematopoiesis including the emergence of erythroid, myeloid and lymphoid cells . iDiscoid offers an easy-to-use, high-throughput, reproducible, and scalable platform to probe multifaceted aspects of human development and blood formation at early post-implantation stage. It will provide a tractable human-based model for drug testing, disease modeling, and a unique cell source for regenerative medicine.
Project description:The human yolk sac (YS) is an extra-embryonic tissue critical for early prenatal life development. It is the first site of haematopoiesis where progenitors differentiate from endoderm within blood islands of the yolk sac contributing initially to primitive erythropoiesis and in subsequent waves to erythro-myeloid and lymphoid differentiation.
Project description:Embryo-like structures generated from stem cells can achieve varying developmental milestones, but none have been shown to progress through gastrulation, neurulation, and organogenesis. Here, we show that "ETiX" mouse embryoids, assembled from embryonic stem cells, trophoblast stem cells and inducible extraembryonic endoderm stem cells, can develop into gastrulating embryoids, and beyond to generate neurulating embryoids, which generate the progenitors needed to create the entire organism. The head-folds of ETiX neurulating embryoids show anterior expression of Otx2, defining forebrain and midbrain regions that resemble those of the natural mouse embryo. Neurulating embryoids also develop beating heart-like structures, trunks comprising a neural tube and somites, tail buds containing neuromesodermal progenitors and primordial germ cells, and gut tubes derived from definitive endoderm. Notably, neurulating embryoids also develop a yolk sac with blood islands. Overall, ETiX neurulating embryoid formation strongly resembles natural embryogenesis, advancing embryo-like development further than any other stem-cell derived model and within extra-embryonic membranes.