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Nature Nov 2021Understanding human organ formation is a scientific challenge with far-reaching medical implications. Three-dimensional stem-cell cultures have provided insights into...
Understanding human organ formation is a scientific challenge with far-reaching medical implications. Three-dimensional stem-cell cultures have provided insights into human cell differentiation. However, current approaches use scaffold-free stem-cell aggregates, which develop non-reproducible tissue shapes and variable cell-fate patterns. This limits their capacity to recapitulate organ formation. Here we present a chip-based culture system that enables self-organization of micropatterned stem cells into precise three-dimensional cell-fate patterns and organ shapes. We use this system to recreate neural tube folding from human stem cells in a dish. Upon neural induction, neural ectoderm folds into a millimetre-long neural tube covered with non-neural ectoderm. Folding occurs at 90% fidelity, and anatomically resembles the developing human neural tube. We find that neural and non-neural ectoderm are necessary and sufficient for folding morphogenesis. We identify two mechanisms drive folding: (1) apical contraction of neural ectoderm, and (2) basal adhesion mediated via extracellular matrix synthesis by non-neural ectoderm. Targeting these two mechanisms using drugs leads to morphological defects similar to neural tube defects. Finally, we show that neural tissue width determines neural tube shape, suggesting that morphology along the anterior-posterior axis depends on neural ectoderm geometry in addition to molecular gradients. Our approach provides a new route to the study of human organ morphogenesis in health and disease.
Topics: Ectoderm; Humans; Models, Biological; Morphogenesis; Neural Plate; Neural Tube; Neural Tube Defects; Organ Culture Techniques; Regeneration; Stem Cells
PubMed: 34707290
DOI: 10.1038/s41586-021-04026-9 -
Cell Stem Cell Sep 2017Directing the fate of human pluripotent stem cells (hPSCs) into different lineages requires variable starting conditions and components with undefined activities,...
Directing the fate of human pluripotent stem cells (hPSCs) into different lineages requires variable starting conditions and components with undefined activities, introducing inconsistencies that confound reproducibility and assessment of specific perturbations. Here we introduce a simple, modular protocol for deriving the four main ectodermal lineages from hPSCs. By precisely varying FGF, BMP, WNT, and TGFβ pathway activity in a minimal, chemically defined medium, we show parallel, robust, and reproducible derivation of neuroectoderm, neural crest (NC), cranial placode (CP), and non-neural ectoderm in multiple hPSC lines, on different substrates independently of cell density. We highlight the utility of this system by interrogating the role of TFAP2 transcription factors in ectodermal differentiation, revealing the importance of TFAP2A in NC and CP specification, and performing a small-molecule screen that identified compounds that further enhance CP differentiation. This platform provides a simple stage for systematic derivation of the entire range of ectodermal cell types.
Topics: Bone Morphogenetic Proteins; Cell Differentiation; Cell Lineage; Ectoderm; Gene Expression Regulation, Developmental; Humans; Neural Crest; Neural Plate; Neural Stem Cells; Phenanthrolines; Pluripotent Stem Cells; Signal Transduction; Small Molecule Libraries; Transcription Factor AP-2
PubMed: 28886367
DOI: 10.1016/j.stem.2017.08.015 -
The EMBO Journal Nov 2017Microglia are resident macrophages of the central nervous system that contribute to homeostasis and neuroinflammation. Although known to play an important role in brain...
Microglia are resident macrophages of the central nervous system that contribute to homeostasis and neuroinflammation. Although known to play an important role in brain development, their exact function has not been fully described. Here, we show that in contrast to healthy adult and inflammation-activated cells, neonatal microglia show a unique myelinogenic and neurogenic phenotype. A CD11c microglial subset that predominates in primary myelinating areas of the developing brain expresses genes for neuronal and glial survival, migration, and differentiation. These cells are the major source of insulin-like growth factor 1, and its selective depletion from CD11c microglia leads to impairment of primary myelination. CD11c-targeted toxin regimens induced a selective transcriptional response in neonates, distinct from adult microglia. CD11c microglia are also found in clusters of repopulating microglia after experimental ablation and in neuroinflammation in adult mice, but despite some similarities, they do not recapitulate neonatal microglial characteristics. We therefore identify a unique phenotype of neonatal microglia that deliver signals necessary for myelination and neurogenesis.
Topics: Aging; Animals; Animals, Newborn; Biomarkers; Brain; CD11c Antigen; Cell Aggregation; Encephalomyelitis, Autoimmune, Experimental; Female; Gene Expression Profiling; Gene Expression Regulation, Developmental; Insulin-Like Growth Factor I; Mice, Inbred C57BL; Microglia; Myelin Sheath; Neural Plate; Neurogenesis; Up-Regulation
PubMed: 28963396
DOI: 10.15252/embj.201696056 -
The International Journal of... 2021The internalization of multi-cellular tissues is a key morphogenetic process during animal development and organ formation. A good example of this is the initial stages... (Review)
Review
The internalization of multi-cellular tissues is a key morphogenetic process during animal development and organ formation. A good example of this is the initial stages of vertebrate central nervous system formation whereby a transient embryonic structure called the neural plate is able to undergo collective cell rearrangements within the dorsal midline. Despite the fact that defects in neural plate midline internalization may result in a series of severe clinical conditions, such as spina bifida and anencephaly, the biochemical and biomechanical details of this process remain only partially characterized. Here we review the main cellular and molecular mechanisms underlying midline cell and tissue internalization during vertebrate neural tube formation. We discuss the contribution of collective cell mechanisms including convergence and extension, as well as apical constriction facilitating midline neural plate shaping. Furthermore, we summarize recent studies that shed light on how the interplay of signaling pathways and cell biomechanics modulate neural plate internalization. In addition, we discuss how adhesion-dependent cell-cell contact appears to be a critical component during midline cell convergence and surface cell contraction via cell-cell mechanical coupling. We envision that more detailed high-resolution quantitative data at both cell and tissue levels will be required to properly model the mechanisms of vertebrate neural plate internalization with the hope of preventing human neural tube defects.
Topics: Animals; Morphogenesis; Neural Plate; Neural Tube; Neurulation; Vertebrates
PubMed: 32930349
DOI: 10.1387/ijdb.200122ca -
Developmental Biology Dec 2018The neural crest has been the main object of my investigations during my career in science, up to now. It is a fascinating topic for an embryologist because of its two... (Review)
Review
The neural crest has been the main object of my investigations during my career in science, up to now. It is a fascinating topic for an embryologist because of its two unique characteristics: its large degree of multipotency and the fact that its development involves a phase during which its component cells migrate all over the embryo and settle in elected sites where they differentiate into a large variety of cell types. Thus, neural crest development raises several specific questions that are at the same time, of general interest: what are the mechanisms controlling the migratory behavior of the cells that detach from the neural plate borders? What are the migration routes taken by the neural crest cells and the environmental factors that make these cells stop in elected sites where they differentiate into a definite series of cell types? When I started to be interested in the neural crest, in the late 1960s, this embryonic structure was the subject of investigations of only a small number of developmental biologists. Fifty years later, it has become the center of interest of many laboratories over the world. The 150 anniversary of its discovery is a relevant opportunity to consider the progress that has been accomplished in our knowledge on the development of this ubiquitous structure, the roles it plays in the physiology of the organism through its numerous and widespread derivatives and its relationships with its environment, as well as the evolutionary advantages it has conferred to the vertebrate phylum. I wish to thank Pr Marianne Bronner, Chief Editor of Developmental Biology and Special Issue Guest Editor, for dedicating a special issue of this journal to this particular structure of the vertebrate embryo. In the following pages, Elisabeth Dupin and I will report some of the highlights of our own acquaintance with the neural crest of the avian embryo, after retracing the main trends of the discoveries of the historical pioneers.
Topics: Animals; Biological Evolution; Body Patterning; Cell Differentiation; Cell Movement; Chick Embryo; Melanocytes; Neural Crest; Neural Plate; Neurogenesis; Quail; Vertebrates
PubMed: 30048640
DOI: 10.1016/j.ydbio.2018.07.019 -
Neurogenesis (Austin, Tex.) 2017The neural crest is a transient cell population that gives rise to various cell types of multiple tissues and organs in the vertebrate embryo. Neural crest cells arise... (Review)
Review
The neural crest is a transient cell population that gives rise to various cell types of multiple tissues and organs in the vertebrate embryo. Neural crest cells arise from the neural plate border, a region localized at the lateral borders of the prospective neural plate. Temporally and spatially coordinated interaction with the adjacent tissues, the non-neural ectoderm, the neural plate and the prospective dorsolateral mesoderm, is required for neural plate border specification. Signaling molecules, namely BMP, Wnt and FGF ligands and corresponding antagonists are derived from these tissues and interact to induce the expression of neural plate border specific genes. The present mini-review focuses on the current understanding of how the NPB territory is formed and accentuates the need for coordinated interaction of BMP and Wnt signaling pathways and precise tissue communication that are required for the definition of the prospective NC in the competent ectoderm.
PubMed: 28352644
DOI: 10.1080/23262133.2017.1292783 -
Development, Growth & Differentiation Jan 2013During development, a flat neural plate rolls up and closes to form a neural tube. This process, called neural tube closure, is complex and requires morphogenetic events... (Review)
Review
During development, a flat neural plate rolls up and closes to form a neural tube. This process, called neural tube closure, is complex and requires morphogenetic events to occur along multiple axes of the neural plate. Recent studies suggest that cell and tissue polarity play a major role in neural tube morphogenesis. While the planar cell polarity pathway is known to be involved in this process, a role for the apicobasal polarity pathway has only recently begun to be elucidated. These studies show that bone morphogenetic proteins can regulate the apicobasal polarity pathway in the neural plate in a cell cycle dependent manner. This dynamically modulates apical junctions in the neural plate, resulting in cell and tissue shape changes that help bend, shape and close the neural tube.
Topics: Animals; Biomechanical Phenomena; Body Patterning; Bone Morphogenetic Proteins; Cell Cycle; Cell Movement; Cell Nucleus; Cell Polarity; Chickens; Epithelium; Neural Plate; Neural Tube; Organogenesis
PubMed: 23277919
DOI: 10.1111/dgd.12030 -
Developmental Biology Dec 2018The neural crest is induced at the edge between the neural plate and the nonneural ectoderm, in an area called the neural (plate) border, during gastrulation and... (Review)
Review
The neural crest is induced at the edge between the neural plate and the nonneural ectoderm, in an area called the neural (plate) border, during gastrulation and neurulation. In recent years, many studies have explored how this domain is patterned, and how the neural crest is induced within this territory, that also participates to the prospective dorsal neural tube, the dorsalmost nonneural ectoderm, as well as placode derivatives in the anterior area. This review highlights the tissue interactions, the cell-cell signaling and the molecular mechanisms involved in this dynamic spatiotemporal patterning, resulting in the induction of the premigratory neural crest. Collectively, these studies allow building a complex neural border and early neural crest gene regulatory network, mostly composed by transcriptional regulations but also, more recently, including novel signaling interactions.
Topics: Animals; Biological Evolution; Body Patterning; Bone Morphogenetic Proteins; Cell Differentiation; Cell Movement; Chick Embryo; Ectoderm; Fibroblast Growth Factors; Gastrulation; Gene Expression Regulation, Developmental; Humans; Melanocytes; Nervous System; Neural Crest; Neural Plate; Neurogenesis; Neurulation; Signal Transduction; Wnt Signaling Pathway; Xenopus Proteins; Xenopus laevis; Zebrafish; Zebrafish Proteins
PubMed: 29852131
DOI: 10.1016/j.ydbio.2018.05.018