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Cell Stem Cell Jun 2023The emergence of the three germ layers and the lineage-specific precursor cells orchestrating organogenesis represent fundamental milestones during early embryonic...
The emergence of the three germ layers and the lineage-specific precursor cells orchestrating organogenesis represent fundamental milestones during early embryonic development. We analyzed the transcriptional profiles of over 400,000 cells from 14 human samples collected from post-conceptional weeks (PCW) 3 to 12 to delineate the dynamic molecular and cellular landscape of early gastrulation and nervous system development. We described the diversification of cell types, the spatial patterning of neural tube cells, and the signaling pathways likely involved in transforming epiblast cells into neuroepithelial cells and then into radial glia. We resolved 24 clusters of radial glial cells along the neural tube and outlined differentiation trajectories for the main classes of neurons. Lastly, we identified conserved and distinctive features across species by comparing early embryonic single-cell transcriptomic profiles between humans and mice. This comprehensive atlas sheds light on the molecular mechanisms underlying gastrulation and early human brain development.
Topics: Humans; Mice; Animals; Gastrulation; Germ Layers; Cell Differentiation; Organogenesis; Brain
PubMed: 37192616
DOI: 10.1016/j.stem.2023.04.016 -
Nature Oct 2023The ability to study human post-implantation development remains limited owing to ethical and technical challenges associated with intrauterine development after...
The ability to study human post-implantation development remains limited owing to ethical and technical challenges associated with intrauterine development after implantation. Embryo-like models with spatially organized morphogenesis and structure of all defining embryonic and extra-embryonic tissues of the post-implantation human conceptus (that is, the embryonic disc, the bilaminar disc, the yolk sac, the chorionic sac and the surrounding trophoblast layer) remain lacking. Mouse naive embryonic stem cells have recently been shown to give rise to embryonic and extra-embryonic stem cells capable of self-assembling into post-gastrulation structured stem-cell-based embryo models with spatially organized morphogenesis (called SEMs). Here we extend those findings to humans using only genetically unmodified human naive embryonic stem cells (cultured in human enhanced naive stem cell medium conditions). Such human fully integrated and complete SEMs recapitulate the organization of nearly all known lineages and compartments of post-implantation human embryos, including the epiblast, the hypoblast, the extra-embryonic mesoderm and the trophoblast layer surrounding the latter compartments. These human complete SEMs demonstrated developmental growth dynamics that resemble key hallmarks of post-implantation stage embryogenesis up to 13-14 days after fertilization (Carnegie stage 6a). These include embryonic disc and bilaminar disc formation, epiblast lumenogenesis, polarized amniogenesis, anterior-posterior symmetry breaking, primordial germ-cell specification, polarized yolk sac with visceral and parietal endoderm formation, extra-embryonic mesoderm expansion that defines a chorionic cavity and a connecting stalk, and a trophoblast-surrounding compartment demonstrating syncytium and lacunae formation. This SEM platform will probably enable the experimental investigation of previously inaccessible windows of human early post implantation up to peri-gastrulation development.
Topics: Humans; Embryo Implantation; Embryo, Mammalian; Embryonic Development; Fertilization; Gastrulation; Germ Layers; Human Embryonic Stem Cells; Trophoblasts; Yolk Sac; Giant Cells
PubMed: 37673118
DOI: 10.1038/s41586-023-06604-5 -
Cell Stem Cell Apr 2023Human stem cell-derived blastoids display similar morphology and cell lineages to normal blastocysts. However, the ability to investigate their developmental potential...
Human stem cell-derived blastoids display similar morphology and cell lineages to normal blastocysts. However, the ability to investigate their developmental potential is limited. Here, we construct cynomolgus monkey blastoids resembling blastocysts in morphology and transcriptomics using naive ESCs. These blastoids develop to embryonic disk with the structures of yolk sac, chorionic cavity, amnion cavity, primitive streak, and connecting stalk along the rostral-caudal axis through prolonged in vitro culture (IVC). Primordial germ cells, gastrulating cells, visceral endoderm/yolk sac endoderm, three germ layers, and hemato-endothelial progenitors in IVC cynomolgus monkey blastoids were observed by single-cell transcriptomics or immunostaining. Moreover, transferring cynomolgus monkey blastoids to surrogates achieves pregnancies, as indicated by progesterone levels and presence of early gestation sacs. Our results reveal the capacity of in vitro gastrulation and in vivo early pregnancy of cynomolgus monkey blastoids, providing a useful system to dissect primate embryonic development without the same ethical concerns and access challenges in human embryo study.
Topics: Pregnancy; Animals; Female; Humans; Gastrulation; Macaca fascicularis; Embryo, Mammalian; Germ Layers; Embryonic Development; Endoderm; Cell Differentiation
PubMed: 37028403
DOI: 10.1016/j.stem.2023.03.009 -
Cell Stem Cell Jun 2009After maternal predetermination gives way to zygotic regulation, a ground state is established within the mammalian embryo. This tabula rasa for embryogenesis is present... (Review)
Review
After maternal predetermination gives way to zygotic regulation, a ground state is established within the mammalian embryo. This tabula rasa for embryogenesis is present only transiently in the preimplantation epiblast. Here, we consider how unrestricted cells are first generated and then prepared for lineage commitment. We propose that two phases of pluripotency can be defined: naive and primed. This distinction extends to pluripotent stem cells derived from embryos or by molecular reprogramming ex vivo.
Topics: Animals; Cell Culture Techniques; Cell Lineage; Embryo, Mammalian; Germ Layers; Humans; Pluripotent Stem Cells; Stem Cells
PubMed: 19497275
DOI: 10.1016/j.stem.2009.05.015 -
Nature Oct 2023The human embryo undergoes morphogenetic transformations following implantation into the uterus, but our knowledge of this crucial stage is limited by the inability to...
The human embryo undergoes morphogenetic transformations following implantation into the uterus, but our knowledge of this crucial stage is limited by the inability to observe the embryo in vivo. Models of the embryo derived from stem cells are important tools for interrogating developmental events and tissue-tissue crosstalk during these stages. Here we establish a model of the human post-implantation embryo, a human embryoid, comprising embryonic and extraembryonic tissues. We combine two types of extraembryonic-like cell generated by overexpression of transcription factors with wild-type embryonic stem cells and promote their self-organization into structures that mimic several aspects of the post-implantation human embryo. These self-organized aggregates contain a pluripotent epiblast-like domain surrounded by extraembryonic-like tissues. Our functional studies demonstrate that the epiblast-like domain robustly differentiates into amnion, extraembryonic mesenchyme and primordial germ cell-like cells in response to bone morphogenetic protein cues. In addition, we identify an inhibitory role for SOX17 in the specification of anterior hypoblast-like cells. Modulation of the subpopulations in the hypoblast-like compartment demonstrates that extraembryonic-like cells influence epiblast-like domain differentiation, highlighting functional tissue-tissue crosstalk. In conclusion, we present a modular, tractable, integrated model of the human embryo that will enable us to probe key questions of human post-implantation development, a critical window during which substantial numbers of pregnancies fail.
Topics: Female; Humans; Pregnancy; Bone Morphogenetic Proteins; Cell Differentiation; Embryo Implantation; Embryo, Mammalian; Embryoid Bodies; Embryonic Development; Germ Layers; Human Embryonic Stem Cells; Models, Biological; Transcription Factors; Pluripotent Stem Cells
PubMed: 37369347
DOI: 10.1038/s41586-023-06368-y -
Cell Stem Cell Sep 2022Despite its clinical and fundamental importance, our understanding of early human development remains limited. Stem cell-derived, embryo-like structures (or embryoids)...
Despite its clinical and fundamental importance, our understanding of early human development remains limited. Stem cell-derived, embryo-like structures (or embryoids) allowing studies of early development without using natural embryos can potentially help fill the knowledge gap of human development. Herein, transcriptome at the single-cell level of a human embryoid model was profiled at different time points. Molecular maps of lineage diversifications from the pluripotent human epiblast toward the amniotic ectoderm, primitive streak/mesoderm, and primordial germ cells were constructed and compared with in vivo primate data. The comparative transcriptome analyses reveal a critical role of NODAL signaling in human mesoderm and primordial germ cell specification, which is further functionally validated. Through comparative transcriptome analyses and validations with human blastocysts and in vitro cultured cynomolgus embryos, we further proposed stringent criteria for distinguishing between human blastocyst trophectoderm and early amniotic ectoderm cells.
Topics: Animals; Blastocyst; Cell Lineage; Ectoderm; Embryo, Mammalian; Germ Layers; Humans; Single-Cell Analysis
PubMed: 36055194
DOI: 10.1016/j.stem.2022.08.009 -
Nature Dec 2019Formation of the three primary germ layers during gastrulation is an essential step in the establishment of the vertebrate body plan and is associated with major...
Formation of the three primary germ layers during gastrulation is an essential step in the establishment of the vertebrate body plan and is associated with major transcriptional changes. Global epigenetic reprogramming accompanies these changes, but the role of the epigenome in regulating early cell-fate choice remains unresolved, and the coordination between different molecular layers is unclear. Here we describe a single-cell multi-omics map of chromatin accessibility, DNA methylation and RNA expression during the onset of gastrulation in mouse embryos. The initial exit from pluripotency coincides with the establishment of a global repressive epigenetic landscape, followed by the emergence of lineage-specific epigenetic patterns during gastrulation. Notably, cells committed to mesoderm and endoderm undergo widespread coordinated epigenetic rearrangements at enhancer marks, driven by ten-eleven translocation (TET)-mediated demethylation and a concomitant increase of accessibility. By contrast, the methylation and accessibility landscape of ectodermal cells is already established in the early epiblast. Hence, regulatory elements associated with each germ layer are either epigenetically primed or remodelled before cell-fate decisions, providing the molecular framework for a hierarchical emergence of the primary germ layers.
Topics: Animals; Cell Differentiation; Cell Lineage; Chromatin; DNA Methylation; Demethylation; Embryoid Bodies; Endoderm; Enhancer Elements, Genetic; Epigenesis, Genetic; Epigenome; Erythropoiesis; Factor Analysis, Statistical; Gastrula; Gastrulation; Gene Expression Regulation, Developmental; Mesoderm; Mice; Pluripotent Stem Cells; RNA; Single-Cell Analysis; Time Factors; Zinc Fingers
PubMed: 31827285
DOI: 10.1038/s41586-019-1825-8 -
Developmental Biology Jun 2021During development, a single cell is transformed into a highly complex organism through progressive cell division, specification and rearrangement. An important... (Review)
Review
During development, a single cell is transformed into a highly complex organism through progressive cell division, specification and rearrangement. An important prerequisite for the emergence of patterns within the developing organism is to establish asymmetries at various scales, ranging from individual cells to the entire embryo, eventually giving rise to the different body structures. This becomes especially apparent during gastrulation, when the earliest major lineage restriction events lead to the formation of the different germ layers. Traditionally, the unfolding of the developmental program from symmetry breaking to germ layer formation has been studied by dissecting the contributions of different signaling pathways and cellular rearrangements in the in vivo context of intact embryos. Recent efforts, using the intrinsic capacity of embryonic stem cells to self-assemble and generate embryo-like structures de novo, have opened new avenues for understanding the many ways by which an embryo can be built and the influence of extrinsic factors therein. Here, we discuss and compare divergent and conserved strategies leading to germ layer formation in embryos as compared to in vitro systems, their upstream molecular cascades and the role of extrinsic factors in this process.
Topics: Animals; Embryonic Stem Cells; Extraembryonic Membranes; Gastrulation; Germ Layers; Humans; Signal Transduction
PubMed: 33352181
DOI: 10.1016/j.ydbio.2020.12.014 -
Nature Sep 2022Gastrulation controls the emergence of cellular diversity and axis patterning in the early embryo. In mammals, this transformation is orchestrated by dynamic signalling...
Gastrulation controls the emergence of cellular diversity and axis patterning in the early embryo. In mammals, this transformation is orchestrated by dynamic signalling centres at the interface of embryonic and extraembryonic tissues. Elucidating the molecular framework of axis formation in vivo is fundamental for our understanding of human development and to advance stem-cell-based regenerative approaches. Here we illuminate early gastrulation of marmoset embryos in utero using spatial transcriptomics and stem-cell-based embryo models. Gaussian process regression-based 3D transcriptomes delineate the emergence of the anterior visceral endoderm, which is hallmarked by conserved (HHEX, LEFTY2, LHX1) and primate-specific (POSTN, SDC4, FZD5) factors. WNT signalling spatially coordinates the formation of the primitive streak in the embryonic disc and is counteracted by SFRP1 and SFRP2 to sustain pluripotency in the anterior domain. Amnion specification occurs at the boundaries of the embryonic disc through ID1, ID2 and ID3 in response to BMP signalling, providing a developmental rationale for amnion differentiation of primate pluripotent stem cells (PSCs). Spatial identity mapping demonstrates that primed marmoset PSCs exhibit the highest similarity to the anterior embryonic disc, whereas naive PSCs resemble the preimplantation epiblast. Our 3D transcriptome models reveal the molecular code of lineage specification in the primate embryo and provide an in vivo reference to decipher human development.
Topics: Animals; Callithrix; Cell Differentiation; Embryo, Mammalian; Endoderm; Female; Gastrulation; Gene Expression Profiling; Germ Layers; Humans; Pluripotent Stem Cells; Uterus
PubMed: 35709828
DOI: 10.1038/s41586-022-04953-1 -
Nature May 2016Implantation of the blastocyst is a developmental milestone in mammalian embryonic development. At this time, a coordinated program of lineage diversification, cell-fate...
Implantation of the blastocyst is a developmental milestone in mammalian embryonic development. At this time, a coordinated program of lineage diversification, cell-fate specification, and morphogenetic movements establishes the generation of extra-embryonic tissues and the embryo proper, and determines the conditions for successful pregnancy and gastrulation. Despite its basic and clinical importance, this process remains mysterious in humans. Here we report the use of a novel in vitro system to study the post-implantation development of the human embryo. We unveil the self-organizing abilities and autonomy of in vitro attached human embryos. We find human-specific molecular signatures of early cell lineage, timing, and architecture. Embryos display key landmarks of normal development, including epiblast expansion, lineage segregation, bi-laminar disc formation, amniotic and yolk sac cavitation, and trophoblast diversification. Our findings highlight the species-specificity of these developmental events and provide a new understanding of early human embryonic development beyond the blastocyst stage. In addition, our study establishes a new model system relevant to early human pregnancy loss. Finally, our work will also assist in the rational design of differentiation protocols of human embryonic stem cells to specific cell types for disease modelling and cell replacement therapy.
Topics: Amnion; Animals; Cell Differentiation; Cell Lineage; Embryo Loss; Embryo, Mammalian; Embryonic Development; Embryonic Stem Cells; Germ Layers; Humans; In Vitro Techniques; Mice; Models, Biological; Species Specificity; Trophoblasts; Yolk Sac
PubMed: 27144363
DOI: 10.1038/nature17948