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Nature Oct 2022Embryonic stem (ES) cells can undergo many aspects of mammalian embryogenesis in vitro, but their developmental potential is substantially extended by interactions with...
Embryonic stem (ES) cells can undergo many aspects of mammalian embryogenesis in vitro, but their developmental potential is substantially extended by interactions with extraembryonic stem cells, including trophoblast stem (TS) cells, extraembryonic endoderm stem (XEN) cells and inducible XEN (iXEN) cells. Here we assembled stem cell-derived embryos in vitro from mouse ES cells, TS cells and iXEN cells and showed that they recapitulate the development of whole natural mouse embryo in utero up to day 8.5 post-fertilization. Our embryo model displays headfolds with defined forebrain and midbrain regions and develops a beating heart-like structure, a trunk comprising a neural tube and somites, a tail bud containing neuromesodermal progenitors, a gut tube, and primordial germ cells. This complete embryo model develops within an extraembryonic yolk sac that initiates blood island development. Notably, we demonstrate that the neurulating embryo model assembled from Pax6-knockout ES cells aggregated with wild-type TS cells and iXEN cells recapitulates the ventral domain expansion of the neural tube that occurs in natural, ubiquitous Pax6-knockout embryos. Thus, these complete embryoids are a powerful in vitro model for dissecting the roles of diverse cell lineages and genes in development. Our results demonstrate the self-organization ability of ES cells and two types of extraembryonic stem cells to reconstitute mammalian development through and beyond gastrulation to neurulation and early organogenesis.
Topics: Animals; Cell Lineage; Embryo, Mammalian; Embryonic Stem Cells; Endoderm; Gastrulation; Heart; Mesencephalon; Mice; Models, Biological; Neural Tube; Neurulation; Organogenesis; PAX6 Transcription Factor; Prosencephalon; Somites
PubMed: 36007540
DOI: 10.1038/s41586-022-05246-3 -
Nature Feb 2023The segmented body plan of vertebrates is established during somitogenesis, a well-studied process in model organisms; however, the details of this process in humans...
The segmented body plan of vertebrates is established during somitogenesis, a well-studied process in model organisms; however, the details of this process in humans remain largely unknown owing to ethical and technical limitations. Despite recent advances with pluripotent stem cell-based approaches, models that robustly recapitulate human somitogenesis in both space and time remain scarce. Here we introduce a pluripotent stem cell-derived mesoderm-based 3D model of human segmentation and somitogenesis-which we termed 'axioloid'-that captures accurately the oscillatory dynamics of the segmentation clock and the morphological and molecular characteristics of sequential somite formation in vitro. Axioloids show proper rostrocaudal patterning of forming segments and robust anterior-posterior FGF-WNT signalling gradients and retinoic acid signalling components. We identify an unexpected critical role of retinoic acid signalling in the stabilization of forming segments, indicating distinct, but also synergistic effects of retinoic acid and extracellular matrix on the formation and epithelialization of somites. Comparative analysis demonstrates marked similarities of axioloids to the human embryo, further validated by the presence of a Hox code in axioloids. Finally, we demonstrate the utility of axioloids for studying the pathogenesis of human congenital spine diseases using induced pluripotent stem cells with mutations in HES7 and MESP2. Our results indicate that axioloids represent a promising platform for the study of axial development and disease in humans.
Topics: Humans; Body Patterning; Cell Culture Techniques, Three Dimensional; Extracellular Matrix; Fibroblast Growth Factors; In Vitro Techniques; Induced Pluripotent Stem Cells; Models, Biological; Mutation; Somites; Spinal Diseases; Tretinoin; Wnt Signaling Pathway
PubMed: 36543322
DOI: 10.1038/s41586-022-05649-2 -
Biomedicine & Pharmacotherapy =... Jun 2023Skeletal muscle is the most extensive tissue in mammals, and they perform several functions; it is derived from paraxial mesodermal somites and undergoes hyperplasia and... (Review)
Review
Skeletal muscle is the most extensive tissue in mammals, and they perform several functions; it is derived from paraxial mesodermal somites and undergoes hyperplasia and hypertrophy to form multinucleated, contractile, and functional muscle fibers. Skeletal muscle is a complex heterogeneous tissue composed of various cell types that establish communication strategies to exchange biological information; therefore, characterizing the cellular heterogeneity and transcriptional signatures of skeletal muscle is central to understanding its ontogeny's details. Studies of skeletal myogenesis have focused primarily on myogenic cells' proliferation, differentiation, migration, and fusion and ignored the intricate network of cells with specific biological functions. The rapid development of single-cell sequencing technology has recently enabled the exploration of skeletal muscle cell types and molecular events during development. This review summarizes the progress in single-cell RNA sequencing and its applications in skeletal myogenesis, which will provide insights into skeletal muscle pathophysiology.
Topics: Animals; Muscle, Skeletal; Muscle Fibers, Skeletal; Cell Differentiation; Mammals; Muscle Development; Developmental Biology; Sequence Analysis, RNA
PubMed: 37003036
DOI: 10.1016/j.biopha.2023.114631 -
The Journal of the American Academy of... Nov 2021Klippel-Feil syndrome (KFS), or congenital fusion of the cervical vertebrae, has been thought to be an extremely rare diagnosis. However, recent literature suggests an...
Klippel-Feil syndrome (KFS), or congenital fusion of the cervical vertebrae, has been thought to be an extremely rare diagnosis. However, recent literature suggests an increased prevalence, with a high proportion of asymptomatic individuals. Occurring as a sporadic mutation or associated with several genes, the pathogenesis involves failure of cervical somite segmentation and differentiation during embryogenesis. Most commonly, the C2-C3 and C5-C6 levels are involved. KFS is associated with other orthopaedic conditions including Sprengel deformity, congenital scoliosis, and cervical spine abnormalities, as well as several visceral pathologies. There are several classification systems, some based on the anatomic levels of fusion and others on its genetic inheritance. Management of patients with KFS primarily involves observation for asymptomatic individuals. Surgical treatment may be for neurologic complaints, correction of deformity, concomitant spinal anomalies, or for associated conditions and varies significantly. Participation in sports is an important consideration. Recommendations for contact sports or activities depend on both the level and the number of vertebrae involved in the fusion. A multidisciplinary team should be involved in the treatment plan and recommendations for complex presentations.
Topics: Cervical Vertebrae; Humans; Klippel-Feil Syndrome; Scapula; Scoliosis; Shoulder Joint
PubMed: 34288888
DOI: 10.5435/JAAOS-D-21-00190 -
Nature Feb 2023The vertebrate body displays a segmental organization that is most conspicuous in the periodic organization of the vertebral column and peripheral nerves. This metameric...
The vertebrate body displays a segmental organization that is most conspicuous in the periodic organization of the vertebral column and peripheral nerves. This metameric organization is first implemented when somites, which contain the precursors of skeletal muscles and vertebrae, are rhythmically generated from the presomitic mesoderm. Somites then become subdivided into anterior and posterior compartments that are essential for vertebral formation and segmental patterning of the peripheral nervous system. How this key somitic subdivision is established remains poorly understood. Here we introduce three-dimensional culture systems of human pluripotent stem cells called somitoids and segmentoids, which recapitulate the formation of somite-like structures with anteroposterior identity. We identify a key function of the segmentation clock in converting temporal rhythmicity into the spatial regularity of anterior and posterior somitic compartments. We show that an initial 'salt and pepper' expression of the segmentation gene MESP2 in the newly formed segment is transformed into compartments of anterior and posterior identity through an active cell-sorting mechanism. Our research demonstrates that the major patterning modules that are involved in somitogenesis, including the clock and wavefront, anteroposterior polarity patterning and somite epithelialization, can be dissociated and operate independently in our in vitro systems. Together, we define a framework for the symmetry-breaking process that initiates somite polarity patterning. Our work provides a platform for decoding general principles of somitogenesis and advancing knowledge of human development.
Topics: Humans; Body Patterning; Cell Culture Techniques, Three Dimensional; In Vitro Techniques; Somites; Spine; Biological Clocks; Epithelium
PubMed: 36543321
DOI: 10.1038/s41586-022-05655-4 -
BMC Biology Feb 2023Skeletal muscle development is a multistep process whose understanding is central in a broad range of fields and applications, from the potential medical value to human...
BACKGROUND
Skeletal muscle development is a multistep process whose understanding is central in a broad range of fields and applications, from the potential medical value to human society, to its economic value associated with improvement of agricultural animals. Skeletal muscle initiates in the somites, with muscle precursor cells generated in the dermomyotome and dermomyotome-derived myotome before muscle differentiation ensues, a developmentally regulated process that is well characterized in model organisms. However, the regulation of skeletal muscle ontogeny during embryonic development remains poorly defined in farm animals, for instance in pig. Here, we profiled gene expression and chromatin accessibility in developing pig somites and myotomes at single-cell resolution.
RESULTS
We identified myogenic cells and other cell types and constructed a differentiation trajectory of pig skeletal muscle ontogeny. Along this trajectory, the dynamic changes in gene expression and chromatin accessibility coincided with the activities of distinct cell type-specific transcription factors. Some novel genes upregulated along the differentiation trajectory showed higher expression levels in muscular dystrophy mice than that in healthy mice, suggesting their involvement in myogenesis. Integrative analysis of chromatin accessibility, gene expression data, and in vitro experiments identified EGR1 and RHOB as critical regulators of pig embryonic myogenesis.
CONCLUSIONS
Collectively, our results enhance our understanding of the molecular and cellular dynamics in pig embryonic myogenesis and offer a high-quality resource for the further study of pig skeletal muscle development and human muscle disease.
Topics: Animals; Mice; Cell Differentiation; Chromatin; Chromatin Immunoprecipitation Sequencing; Gene Expression Regulation, Developmental; Muscle Development; Muscle, Skeletal; Single-Cell Analysis; Single-Cell Gene Expression Analysis; Swine
PubMed: 36726129
DOI: 10.1186/s12915-023-01519-z -
Nature Jun 2020Gastruloids are three-dimensional aggregates of embryonic stem cells that display key features of mammalian development after implantation, including germ-layer...
Gastruloids are three-dimensional aggregates of embryonic stem cells that display key features of mammalian development after implantation, including germ-layer specification and axial organization. To date, the expression pattern of only a small number of genes in gastruloids has been explored with microscopy, and the extent to which genome-wide expression patterns in gastruloids mimic those in embryos is unclear. Here we compare mouse gastruloids with mouse embryos using single-cell RNA sequencing and spatial transcriptomics. We identify various embryonic cell types that were not previously known to be present in gastruloids, and show that key regulators of somitogenesis are expressed similarly between embryos and gastruloids. Using live imaging, we show that the somitogenesis clock is active in gastruloids and has dynamics that resemble those in vivo. Because gastruloids can be grown in large quantities, we performed a small screen that revealed how reduced FGF signalling induces a short-tail phenotype in embryos. Finally, we demonstrate that embedding in Matrigel induces gastruloids to generate somites with the correct rostral-caudal patterning, which appear sequentially in an anterior-to-posterior direction over time. This study thus shows the power of gastruloids as a model system for exploring development and somitogenesis in vitro in a high-throughput manner.
Topics: Animals; Collagen; Drug Combinations; Embryo, Mammalian; Embryonic Development; Female; Gastrula; Gene Expression Regulation, Developmental; Laminin; Male; Mice; Mouse Embryonic Stem Cells; Organoids; Proteoglycans; RNA-Seq; Single-Cell Analysis; Somites; Time Factors; Transcriptome
PubMed: 32076263
DOI: 10.1038/s41586-020-2024-3 -
Cell Feb 2023Axial development of mammals involves coordinated morphogenetic events, including axial elongation, somitogenesis, and neural tube formation. To gain insight into the...
Axial development of mammals involves coordinated morphogenetic events, including axial elongation, somitogenesis, and neural tube formation. To gain insight into the signals controlling the dynamics of human axial morphogenesis, we generated axially elongating organoids by inducing anteroposterior symmetry breaking of spatially coupled epithelial cysts derived from human pluripotent stem cells. Each organoid was composed of a neural tube flanked by presomitic mesoderm sequentially segmented into somites. Periodic activation of the somite differentiation gene MESP2 coincided in space and time with anteriorly traveling segmentation clock waves in the presomitic mesoderm of the organoids, recapitulating critical aspects of somitogenesis. Timed perturbations demonstrated that FGF and WNT signaling play distinct roles in axial elongation and somitogenesis, and that FGF signaling gradients drive segmentation clock waves. By generating and perturbing organoids that robustly recapitulate the architecture of multiple axial tissues in human embryos, this work offers a means to dissect mechanisms underlying human embryogenesis.
Topics: Animals; Humans; Body Patterning; Embryonic Development; Gene Expression Regulation, Developmental; Mammals; Mesoderm; Morphogenesis; Somites; Wnt Signaling Pathway; Organoids
PubMed: 36657441
DOI: 10.1016/j.cell.2022.12.042 -
Journal of Cachexia, Sarcopenia and... Dec 2022Human pluripotent stem cell-derived muscle models show great potential for translational research. Here, we describe developmentally inspired methods for the derivation...
BACKGROUND
Human pluripotent stem cell-derived muscle models show great potential for translational research. Here, we describe developmentally inspired methods for the derivation of skeletal muscle cells and their utility in skeletal muscle tissue engineering with the aim to model skeletal muscle regeneration and dystrophy in vitro.
METHODS
Key steps include the directed differentiation of human pluripotent stem cells to embryonic muscle progenitors followed by primary and secondary foetal myogenesis into three-dimensional muscle. To simulate Duchenne muscular dystrophy (DMD), a patient-specific induced pluripotent stem cell line was compared to a CRISPR/Cas9-edited isogenic control line.
RESULTS
The established skeletal muscle differentiation protocol robustly and faithfully recapitulates critical steps of embryonic myogenesis in two-dimensional and three-dimensional cultures, resulting in functional human skeletal muscle organoids (SMOs) and engineered skeletal muscles (ESMs) with a regeneration-competent satellite-like cell pool. Tissue-engineered muscle exhibits organotypic maturation and function (up to 5.7 ± 0.5 mN tetanic twitch tension at 100 Hz in ESM). Contractile performance could be further enhanced by timed thyroid hormone treatment, increasing the speed of contraction (time to peak contraction) as well as relaxation (time to 50% relaxation) of single twitches from 107 ± 2 to 75 ± 4 ms (P < 0.05) and from 146 ± 6 to 100 ± 6 ms (P < 0.05), respectively. Satellite-like cells could be documented as largely quiescent PAX7 cells (75 ± 6% Ki67 ) located adjacent to muscle fibres confined under a laminin-containing basal membrane. Activation of the engineered satellite-like cell niche was documented in a cardiotoxin injury model with marked recovery of contractility to 57 ± 8% of the pre-injury force 21 days post-injury (P < 0.05 compared to Day 2 post-injury), which was completely blocked by preceding irradiation. Absence of dystrophin in DMD ESM caused a marked reduction of contractile force (-35 ± 7%, P < 0.05) and impaired expression of fast myosin isoforms resulting in prolonged contraction (175 ± 14 ms, P < 0.05 vs. gene-edited control) and relaxation (238 ± 22 ms, P < 0.05 vs. gene-edited control) times. Restoration of dystrophin levels by gene editing rescued the DMD phenotype in ESM.
CONCLUSIONS
We introduce human muscle models with canonical properties of bona fide skeletal muscle in vivo to study muscle development, maturation, disease and repair.
Topics: Humans; Muscular Dystrophy, Duchenne; Muscle, Skeletal; Muscle Development; Satellite Cells, Skeletal Muscle; Muscle Fibers, Skeletal
PubMed: 36254806
DOI: 10.1002/jcsm.13094 -
Science (New York, N.Y.) Dec 2020Post-implantation embryogenesis is a highly dynamic process comprising multiple lineage decisions and morphogenetic changes that are inaccessible to deep analysis in...
Post-implantation embryogenesis is a highly dynamic process comprising multiple lineage decisions and morphogenetic changes that are inaccessible to deep analysis in vivo. We found that pluripotent mouse embryonic stem cells (mESCs) form aggregates that upon embedding in an extracellular matrix compound induce the formation of highly organized "trunk-like structures" (TLSs) comprising the neural tube and somites. Comparative single-cell RNA sequencing analysis confirmed that this process is highly analogous to mouse development and follows the same stepwise gene-regulatory program. knockout TLSs developed additional neural tubes mirroring the embryonic mutant phenotype, and chemical modulation could induce excess somite formation. TLSs thus reveal an advanced level of self-organization and provide a powerful platform for investigating post-implantation embryogenesis in a dish.
Topics: Animals; Embryonic Development; Gene Expression Regulation, Developmental; Mice; Mice, Knockout; Mouse Embryonic Stem Cells; Neural Tube; Pyridines; Pyrimidines; Somites; T-Box Domain Proteins; Wnt Proteins
PubMed: 33303587
DOI: 10.1126/science.aba4937