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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 -
Science (New York, N.Y.) Aug 2023The extraembryonic yolk sac (YS) ensures delivery of nutritional support and oxygen to the developing embryo but remains ill-defined in humans. We therefore assembled a...
The extraembryonic yolk sac (YS) ensures delivery of nutritional support and oxygen to the developing embryo but remains ill-defined in humans. We therefore assembled a comprehensive multiomic reference of the human YS from 3 to 8 postconception weeks by integrating single-cell protein and gene expression data. Beyond its recognized role as a site of hematopoiesis, we highlight roles in metabolism, coagulation, vascular development, and hematopoietic regulation. We reconstructed the emergence and decline of YS hematopoietic stem and progenitor cells from hemogenic endothelium and revealed a YS-specific accelerated route to macrophage production that seeds developing organs. The multiorgan functions of the YS are superseded as intraembryonic organs develop, effecting a multifaceted relay of vital functions as pregnancy proceeds.
Topics: Female; Humans; Pregnancy; Blood Coagulation; Macrophages; Yolk Sac; Embryonic Development; Atlases as Topic; Gene Expression; Gene Expression Profiling; Hematopoiesis; Liver
PubMed: 37590359
DOI: 10.1126/science.add7564 -
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 -
Cell Reports Methods Apr 2023Although the differentiation of human induced pluripotent stem cells (hiPSCs) into various types of blood cells has been well established, approaches for clinical-scale...
Although the differentiation of human induced pluripotent stem cells (hiPSCs) into various types of blood cells has been well established, approaches for clinical-scale production of multipotent hematopoietic progenitor cells (HPCs) remain challenging. We found that hiPSCs cocultured with stromal cells as spheroids (hematopoietic spheroids [Hp-spheroids]) can grow in a stirred bioreactor and develop into yolk sac-like organoids without the addition of exogenous factors. Hp-spheroid-induced organoids recapitulated a yolk sac-characteristic cellular complement and structures as well as the functional ability to generate HPCs with lympho-myeloid potential. Moreover, sequential hemato-vascular ontogenesis could also be observed during organoid formation. We demonstrated that organoid-induced HPCs can be differentiated into erythroid cells, macrophages, and T lymphocytes with current maturation protocols. Notably, the Hp-spheroid system can be performed in an autologous and xeno-free manner, thereby improving the feasibility of bulk production of hiPSC-derived HPCs in clinical, therapeutic contexts.
Topics: Humans; Induced Pluripotent Stem Cells; Yolk Sac; Hematopoietic Stem Cells; Organoids; Activities of Daily Living
PubMed: 37159663
DOI: 10.1016/j.crmeth.2023.100460 -
Nature Oct 2023Investigating human development is a substantial scientific challenge due to the technical and ethical limitations of working with embryonic samples. In the face of...
Investigating human development is a substantial scientific challenge due to the technical and ethical limitations of working with embryonic samples. In the face of these difficulties, stem cells have provided an alternative to experimentally model inaccessible stages of human development in vitro. Here we show that human pluripotent stem cells can be triggered to self-organize into three-dimensional structures that recapitulate some key spatiotemporal events of early human post-implantation embryonic development. Our system reproducibly captures spontaneous differentiation and co-development of embryonic epiblast-like and extra-embryonic hypoblast-like lineages, establishes key signalling hubs with secreted modulators and undergoes symmetry breaking-like events. Single-cell transcriptomics confirms differentiation into diverse cell states of the perigastrulating human embryo without establishing placental cell types, including signatures of post-implantation epiblast, amniotic ectoderm, primitive streak, mesoderm, early extra-embryonic endoderm, as well as initial yolk sac induction. Collectively, our system captures key features of human embryonic development spanning from Carnegie stage 4-7, offering a reproducible, tractable and scalable experimental platform to understand the basic cellular and molecular mechanisms that underlie human development, including new opportunities to dissect congenital pathologies with high throughput.
Topics: Female; Humans; Pregnancy; Cell Differentiation; Cell Lineage; Embryo Implantation; Embryonic Development; Germ Layers; Human Embryonic Stem Cells; Placenta; Pluripotent Stem Cells; Primitive Streak; Yolk Sac
PubMed: 37369348
DOI: 10.1038/s41586-023-06354-4 -
Nature Communications Jul 2020Human embryogenesis is hallmarked by two phases of yolk sac development. The primate hypoblast gives rise to a transient primary yolk sac, which is rapidly superseded by... (Review)
Review
Human embryogenesis is hallmarked by two phases of yolk sac development. The primate hypoblast gives rise to a transient primary yolk sac, which is rapidly superseded by a secondary yolk sac during gastrulation. Moreover, primate embryos form extraembryonic mesoderm prior to gastrulation, in contrast to mouse. The function of the primary yolk sac and the origin of extraembryonic mesoderm remain unclear. Here, we hypothesise that the hypoblast-derived primary yolk sac serves as a source for early extraembryonic mesoderm, which is supplemented with mesoderm from the gastrulating embryo. We discuss the intricate relationship between the yolk sac and the primate embryo and highlight the pivotal role of the yolk sac as a multifunctional hub for haematopoiesis, germ cell development and nutritional supply.
Topics: Animals; Cell Differentiation; Embryonic Development; Embryonic Germ Cells; Hematopoiesis; Mesoderm; Primates; Yolk Sac
PubMed: 32724077
DOI: 10.1038/s41467-020-17575-w -
Science Immunology Mar 2020Tissue-resident macrophages are a diverse population of cells that perform specialized functions including sustaining tissue homeostasis and tissue surveillance. Here,...
Tissue-resident macrophages are a diverse population of cells that perform specialized functions including sustaining tissue homeostasis and tissue surveillance. Here, we report an interstitial subset of CD169 lung-resident macrophages that are transcriptionally and developmentally distinct from alveolar macrophages (AMs). They are primarily localized around the airways and are found in close proximity to the sympathetic nerves in the bronchovascular bundle. These nerve- and airway-associated macrophages (NAMs) are tissue resident, yolk sac derived, self-renewing, and do not require CCR2 monocytes for development or maintenance. Unlike AMs, the development of NAMs requires CSF1 but not GM-CSF. Bulk population and single-cell transcriptome analysis indicated that NAMs are distinct from other lung-resident macrophage subsets and highly express immunoregulatory genes under steady-state and inflammatory conditions. NAMs proliferated robustly after influenza infection and activation with the TLR3 ligand poly(I:C), and in their absence, the inflammatory response was augmented, resulting in excessive production of inflammatory cytokines and innate immune cell infiltration. Overall, our study provides insights into a distinct subset of airway-associated pulmonary macrophages that function to maintain immune and tissue homeostasis.
Topics: Animals; Homeostasis; Macrophage Colony-Stimulating Factor; Macrophages, Alveolar; Mice; Mice, Inbred C57BL; Mice, Transgenic; Neurons; Yolk Sac
PubMed: 32220976
DOI: 10.1126/sciimmunol.aax8756 -
Developmental Biology Aug 2022Macrophages are vital inhabitants of the developing heart. Nonetheless, their key role is not limited to prenatal processes, as embryo-derived macrophages govern the... (Review)
Review
Macrophages are vital inhabitants of the developing heart. Nonetheless, their key role is not limited to prenatal processes, as embryo-derived macrophages govern the pool of cardiac macrophages also postnatally. Namely, embryonic cardiac macrophages are of yolk sac-, embryonic monocyte-, and heart-tissue origin. They persist, self-renew and/or are gradually replaced by blood monocytes and assume microenvironment-dependent macrophage phenotypes both in the pre- and postnatal heart. Still, it is during embryonic development that cardiac macrophages gain tissue-specific phenotypes and multifunctional diverse properties. Currently, with the emergence of newer research methods, novel facts about embryonic macrophage ontogeny, lifecycle, and repertoire of functions have been revealed. Meeting the high interest in cardiac macrophages, we present this up-to-date overview of embryonic cardiac macrophages, emphasizing the fundamental concepts and discrepancies related to macrophage characteristics, current research gaps, and potential future developments in this field.
Topics: Embryo, Mammalian; Heart; Macrophages; Monocytes; Yolk Sac
PubMed: 35533717
DOI: 10.1016/j.ydbio.2022.05.003 -
Philosophical Transactions of the Royal... Dec 2022Embryonic development and growth in placental mammals proceeds with the support of exchanges of gases, nutrients and waste products between maternal tissues and... (Review)
Review
Embryonic development and growth in placental mammals proceeds with the support of exchanges of gases, nutrients and waste products between maternal tissues and offspring. Murine embryos are surrounded by several extraembryonic membranes, parietal and visceral yolk sacs, and amnion in the uterus. Notably, the parietal yolk sac is the most outer membrane, consists of three layers, trophoblasts and parietal endoderm (PaE) cells, and is separated by a thick basal lamina termed Reichert's membrane (RM). RM is composed of extracellular matrix (ECM) initially formed as the basement membrane of the trophectoderm of pre-implanted embryos and followed by the heavy deposition of ECM mainly produced in PaE cells of post-implanted embryos. In addition to the physiological roles of RM, such as gas and nutrient exchange, it also plays a crucial role in cushioning and dispersing intrauterine pressures exerted on embryos for normal egg-cylinder morphogenesis. Mechanistically, such intrauterine pressures generated by uterine smooth muscle contractions appear to be involved in the elongation of the egg-cylinder shape, along with primary axis formation, as an important biomechanical element . This review focuses on our current views of the roles of RM in properly buffering intrauterine mechanical forces for mouse egg-cylinder morphogenesis. This article is part of the theme issue 'Extraembryonic tissues: exploring concepts, definitions and functions across the animal kingdom'.
Topics: Animals; Basement Membrane; Endoderm; Female; Gases; Mammals; Mice; Placenta; Pregnancy; Waste Products; Yolk Sac
PubMed: 36252218
DOI: 10.1098/rstb.2021.0257 -
The Journal of Experimental Medicine Mar 2022Atkins et al. (2022. J. Exp. Med.https://doi.org/10.1084/jem.20211924) create a PSC differentiation model for human yolk sac hematopoiesis and discover multipotent...
Atkins et al. (2022. J. Exp. Med.https://doi.org/10.1084/jem.20211924) create a PSC differentiation model for human yolk sac hematopoiesis and discover multipotent progenitors with erythro-myeloid and T lymphoid potential. The multipotent progenitors emerge via hemogenic endothelium and share origin with primitive erythroid wave in KDR+CD235a/b+ mesoderm.
Topics: Hematopoiesis; Humans; Mesoderm; Yolk Sac
PubMed: 35201267
DOI: 10.1084/jem.20212315