Ex Utero Development of Post-Gastrulation Synthetic-Embryos Generated Solely from Mouse Naïve Pluripotent Stem Cells [scRNA-seq]
Ontology highlight
ABSTRACT: Different types of in vitro expanded stem cells can contribute to embryonic or extra-embryonic compartments after microinjection into blastocysts. However, whether stem cells could give rise to advanced gastrulating whole embryo-like structures with both embryonic and extra-embryonic compartments, without relying on a micro-injected host embryo, remains to be achieved. Thus far, in vitro aggregated stem cells have failed to generate post-gastrulation embryos ex utero or in utero, which partially resulted from the lack of methods for prolonged expansion of embryos until advanced developmental stages ex utero. Here we adapt recently optimized platform and conditions for ex utero growth of natural embryos, to generate complete mouse synthetic embryos, with both embryonic and extra-embryonic compartments, and by starting solely from naïve ESCs. The latter is achieved following co-aggregating non-transduced naïve ESCs, with Cdx2- and Gata4- transiently pulsed naïve ESCs, to promote their trophoblast and primitive endoderm lineage induction, respectively. The obtained synthetic embryos adequately advance in this platform through developmental milestones and accomplish gastrulation and develop organs progenitors within normally developed extra-embryonic compartments. Our findings highlight the plastic developmental potential of the naïve pluripotent state to functionally self-organize and reconstitute the entire early mammalian embryo.
Project description:Different types of in vitro expanded stem cells can contribute to embryonic or extra-embryonic compartments after microinjection into blastocysts. However, whether stem cells could give rise to advanced gastrulating whole embryo-like structures with both embryonic and extra-embryonic compartments, without relying on a micro-injected host embryo, remains to be achieved. Thus far, in vitro aggregated stem cells have failed to generate post-gastrulation embryos ex utero or in utero, which partially resulted from the lack of methods for prolonged expansion of embryos until advanced developmental stages ex utero. Here we adapt recently optimized platform and conditions for ex utero growth of natural embryos, to generate complete mouse synthetic embryos, with both embryonic and extra-embryonic compartments, and by starting solely from naïve ESCs. The latter is achieved following co-aggregating non-transduced naïve ESCs, with Cdx2- and Gata4- transiently pulsed naïve ESCs, to promote their trophoblast and primitive endoderm lineage induction, respectively. The obtained synthetic embryos adequately advance in this platform through developmental milestones and accomplish gastrulation and develop organs progenitors within normally developed extra-embryonic compartments. Our findings highlight the plastic developmental potential of the naïve pluripotent state to functionally self-organize and reconstitute the entire early mammalian embryo.
Project description:Establishment of the mammalian body plan occurs shortly after the embryo implants into the maternal uterus, and our understanding of post-implantation developmental processes remains limited. While methods for in vitro culture of pre- and peri-implantation mouse embryos are routinely utilized, approaches for robust culture of post-implantation embryos from egg cylinder stages until advanced organogenesis remain to be established. We develop herein highly stable ex utero post-implantation mouse embryo culture platforms, that enable appropriate development of embryos before gastrulation (E5.5) until the hind limb formation stage (E11). Late gastrulating embryos (E7.5) are grown in 3D rotating bottles settings, while extended culture from pre-gastrulation stages (E5.5 or E6.5) requires a combination of novel static and rotating bottle culture protocols. Histological, molecular, and single cell RNA-seq analysis validate that the ex utero developed embryos recapitulate precisely in utero development. This culture system is amenable to introducing a variety of embryonic perturbations and micro-manipulations that can be followed ex utero for up to 6 days. Establishment of a system to robustly grow normal mouse embryos ex utero from pre-gastrulation to advanced organogenesis represents a valuable tool to investigate post-implantation embryogenesis, eliminating the uterine barrier to mechanistically interrogate morphogenesis and tissue specification in mammals.
Project description:Our ability to study early human post-implantation development remains highly limited due to the ethical and technical challenges associated with intrauterine development of the human embryo after implantation. Despite the great progress made on human blastoids or gastruloids, such elegant models do not constitute an integrated synthetic stem cell-derived embryoid models (SEMs) that includes all the key extra-embryonic tissues of the early pre-gastrulating implanted human conceptus (e.g. hypoblast, yolk-sac, trophoblasts, amnion and extraembryonic mesoderm), and thus, do not recapitulate post-implantation epiblast development within the context of these extra-embryonic compartments. Mouse naïve pluripotent stem cells (PSCs) have recently been shown to give rise to embryonic and extra-embryonic stem cells capable of self-assembling into post-gastrulation mouse SEMs, while bypassing the blastocyst-like stage, and eventually initiating organogenesis ex utero. Here, we implement critical adaptations to extend these finding in humans, using only genetically unmodified human naïve PSCs, circumventing the need for ectopic expression of lineage promoting transgenes. Such integrated human SEMs recapitulate all known compartments of early post-implantation stage human embryos, including epiblast, hypoblast, extra-embryonic mesoderm, and trophoblast surrounding the latter layers. The organized human SEMs recapitulate key hallmarks of post-implantation stage embryogenesis up to 13-14 days post-fertilization (dpf, Carnegie stage 6a), such as bilaminar disk formation, epiblast lumenogenesis, amniogenesis, anterior-posterior symmetry breaking, PGC specification, primary and secondary yolk sac formation, and extra-embryonic mesoderm expansion that defines a chorionic cavity and a connective stalk. This new platform constitutes a tractable stem cell-based model for experimentally interrogating previously inaccessible windows of human early peri- and post-implantation development.
Project description:Our ability to study early human post-implantation development remains highly limited due to the ethical and technical challenges associated with intrauterine development of the human embryo after implantation. Despite the great progress made on human blastoids or gastruloids, such elegant models do not constitute an integrated synthetic stem cell-derived embryoid models (SEMs) that includes all the key extra-embryonic tissues of the early pre-gastrulating implanted human conceptus (e.g. hypoblast, yolk-sac, trophoblasts, amnion and extraembryonic mesoderm), and thus, do not recapitulate post-implantation epiblast development within the context of these extra-embryonic compartments. Mouse naïve pluripotent stem cells (PSCs) have recently been shown to give rise to embryonic and extra-embryonic stem cells capable of self-assembling into post-gastrulation mouse SEMs, while bypassing the blastocyst-like stage, and eventually initiating organogenesis ex utero. Here, we implement critical adaptations to extend these finding in humans, using only genetically unmodified human naïve PSCs, circumventing the need for ectopic expression of lineage promoting transgenes. Such integrated human SEMs recapitulate all known compartments of early post-implantation stage human embryos, including epiblast, hypoblast, extra-embryonic mesoderm, and trophoblast surrounding the latter layers. The organized human SEMs recapitulate key hallmarks of post-implantation stage embryogenesis up to 13-14 days post-fertilization (dpf, Carnegie stage 6a), such as bilaminar disk formation, epiblast lumenogenesis, amniogenesis, anterior-posterior symmetry breaking, PGC specification, primary and secondary yolk sac formation, and extra-embryonic mesoderm expansion that defines a chorionic cavity and a connective stalk. This new platform constitutes a tractable stem cell-based model for experimentally interrogating previously inaccessible windows of human early peri- and post-implantation development.
Project description:Our ability to study early human post-implantation development remains highly limited due to the ethical and technical challenges associated with intrauterine development of the human embryo after implantation. Despite the great progress made on human blastoids or gastruloids, such elegant models do not constitute an integrated synthetic stem cell-derived embryoid models (SEMs) that includes all the key extra-embryonic tissues of the early pre-gastrulating implanted human conceptus (e.g. hypoblast, yolk-sac, trophoblasts, amnion and extraembryonic mesoderm), and thus, do not recapitulate post-implantation epiblast development within the context of these extra-embryonic compartments. Mouse naïve pluripotent stem cells (PSCs) have recently been shown to give rise to embryonic and extra-embryonic stem cells capable of self-assembling into post-gastrulation mouse SEMs, while bypassing the blastocyst-like stage, and eventually initiating organogenesis ex utero. Here, we implement critical adaptations to extend these finding in humans, using only genetically unmodified human naïve PSCs, circumventing the need for ectopic expression of lineage promoting transgenes. Such integrated human SEMs recapitulate all known compartments of early post-implantation stage human embryos, including epiblast, hypoblast, extra-embryonic mesoderm, and trophoblast surrounding the latter layers. The organized human SEMs recapitulate key hallmarks of post-implantation stage embryogenesis up to 13-14 days post-fertilization (dpf, Carnegie stage 6a), such as bilaminar disk formation, epiblast lumenogenesis, amniogenesis, anterior-posterior symmetry breaking, PGC specification, primary and secondary yolk sac formation, and extra-embryonic mesoderm expansion that defines a chorionic cavity and a connective stalk. This new platform constitutes a tractable stem cell-based model for experimentally interrogating previously inaccessible windows of human early peri- and post-implantation development.
Project description:Our ability to study early human post-implantation development remains highly limited due to the ethical and technical challenges associated with intrauterine development of the human embryo after implantation. Despite the great progress made on human blastoids or gastruloids, such elegant models do not constitute an integrated synthetic stem cell-derived embryoid models (SEMs) that includes all the key extra-embryonic tissues of the early pre-gastrulating implanted human conceptus (e.g. hypoblast, yolk-sac, trophoblasts, amnion and extraembryonic mesoderm), and thus, do not recapitulate post-implantation epiblast development within the context of these extra-embryonic compartments. Mouse naïve pluripotent stem cells (PSCs) have recently been shown to give rise to embryonic and extra-embryonic stem cells capable of self-assembling into post-gastrulation mouse SEMs, while bypassing the blastocyst-like stage, and eventually initiating organogenesis ex utero. Here, we implement critical adaptations to extend these finding in humans, using only genetically unmodified human naïve PSCs, circumventing the need for ectopic expression of lineage promoting transgenes. Such integrated human SEMs recapitulate all known compartments of early post-implantation stage human embryos, including epiblast, hypoblast, extra-embryonic mesoderm, and trophoblast surrounding the latter layers. The organized human SEMs recapitulate key hallmarks of post-implantation stage embryogenesis up to 13-14 days post-fertilization (dpf, Carnegie stage 6a), such as bilaminar disk formation, epiblast lumenogenesis, amniogenesis, anterior-posterior symmetry breaking, PGC specification, primary and secondary yolk sac formation, and extra-embryonic mesoderm expansion that defines a chorionic cavity and a connective stalk. This new platform constitutes a tractable stem cell-based model for experimentally interrogating previously inaccessible windows of human early peri- and post-implantation development.
Project description:Epiblast cells in the early post-implantation stage mammalian embryo undergo a transition described as lineage priming before cell fate allocation, but signaling pathways acting upstream remain ill defined. Genetic studies demonstrate that Smad2/3 double-mutant mouse embryos die shortly after implantation. To learn more about the molecular disturbances underlying this abrupt failure, here we characterised Smad2/3-deificient embryonic stem cells (ESCs). We found that Smad2/3 double-knockout ESCs induced to form epiblast-like cells (EpiLCs) display changes in naïve and primed pluripotency marker gene expression, associated with the disruption of Oct4-bound distal regulatory element. In the absence of Smad2/3, we observed enhanced Bmp target gene expression and de-repression of extra-embryonic gene expression. Cell fate allocation into all three embryonic germ lakers is disrupted. Collectively, these experiments demonstrate that combinatorial Smad2/3 functional activities are required to maintain distinct embryonic and/or extra-embryonic cell identity during lineage priming in the epiblast before gastrulation.
Project description:Epiblast cells in the early post-implantation stage mammalian embryo undergo a transition described as lineage priming before cell fate allocation, but signaling pathways acting upstream remain ill defined. Genetic studies demonstrate that Smad2/3 double-mutant mouse embryos die shortly after implantation. To learn more about the molecular disturbances underlying this abrupt failure, here we characterised Smad2/3-deificient embryonic stem cells (ESCs). We found that Smad2/3 double-knockout ESCs induced to form epiblast-like cells (EpiLCs) display changes in naïve and primed pluripotency marker gene expression, associated with the disruption of Oct4-bound distal regulatory element. In the absence of Smad2/3, we observed enhanced Bmp target gene expression and de-repression of extra-embryonic gene expression. Cell fate allocation into all three embryonic germ lakers is disrupted. Collectively, these experiments demonstrate that combinatorial Smad2/3 functional activities are required to maintain distinct embryonic and/or extra-embryonic cell identity during lineage priming in the epiblast before gastrulation.
Project description:Epiblast cells in the early post-implantation stage mammalian embryo undergo a transition described as lineage priming before cell fate allocation, but signaling pathways acting upstream remain ill defined. Genetic studies demonstrate that Smad2/3 double-mutant mouse embryos die shortly after implantation. To learn more about the molecular disturbances underlying this abrupt failure, here we characterised Smad2/3-deificient embryonic stem cells (ESCs). We found that Smad2/3 double-knockout ESCs induced to form epiblast-like cells (EpiLCs) display changes in naïve and primed pluripotency marker gene expression, associated with the disruption of Oct4-bound distal regulatory element. In the absence of Smad2/3, we observed enhanced Bmp target gene expression and de-repression of extra-embryonic gene expression. Cell fate allocation into all three embryonic germ lakers is disrupted. Collectively, these experiments demonstrate that combinatorial Smad2/3 functional activities are required to maintain distinct embryonic and/or extra-embryonic cell identity during lineage priming in the epiblast before gastrulation.
Project description:Embryonic stem cells (ESCs) can exist in at least two states that transcriptionally resemble different stages of embryonic development. Naïve ESCs resemble peri-implantation stages and primed ESCs the pre-gastrulation epiblast. In mouse, primed ESCs give rise to definitive endoderm in response to pathways downstream of Nodal and Wnt signalling. However, when these cytokines are applied to naïve ESCs, they differentiate to a cell type that approximates early primitive endoderm (PrE), the blastocyst stage progenitor layer that gives rise to the extra-embryonic endoderm. Here, we apply this context dependency to human ESCs, showing that these cytokines drive the differentiation of naïve pluripotent cells to generate extra-embryonic PrE, or hypoblast, and, as in mouse, expanded as an in vitro model for naïve extra-embryonic endoderm (nEnd) in defined conditions. Consistent with observations made in mouse, human PrE differentiation is dependent on FGF signalling in vitro, and we show, that by inhibiting FGF receptor signalling, we could simplify naïve pluripotent culture such that inhibitor requirements closer resembled those used in mouse. These nEnd cultures represent stable extra-embryonic endoderm, or human hypoblast, cell lines.