Cerebral organoids model human brain development and microcephaly
TL;DR: A human pluripotent stem cell-derived three-dimensional organoid culture system that develops various discrete, although interdependent, brain regions that include a cerebral cortex containing progenitor populations that organize and produce mature cortical neuron subtypes is developed.
Abstract: The complexity of the human brain has made it difficult to study many brain disorders in model organisms, highlighting the need for an in vitro model of human brain development Here we have developed a human pluripotent stem cell-derived three-dimensional organoid culture system, termed cerebral organoids, that develop various discrete, although interdependent, brain regions These include a cerebral cortex containing progenitor populations that organize and produce mature cortical neuron subtypes Furthermore, cerebral organoids are shown to recapitulate features of human cortical development, namely characteristic progenitor zone organization with abundant outer radial glial stem cells Finally, we use RNA interference and patient-specific induced pluripotent stem cells to model microcephaly, a disorder that has been difficult to recapitulate in mice We demonstrate premature neuronal differentiation in patient organoids, a defect that could help to explain the disease phenotype Together, these data show that three-dimensional organoids can recapitulate development and disease even in this most complex human tissue
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TL;DR: It is demonstrated that the intrinsic tendency of stem cells to make patterns can be harnessed by controlling colony geometries and provide a quantitative assay for studying paracrine signaling in early development.
Abstract: Embryos allocate cells to the three germ layers in a spatially ordered sequence. Human embryonic stem cells (hESCs) can generate the three germ layers in culture; however, differentiation is typically heterogeneous and spatially disordered. We show that geometric confinement is sufficient to trigger self-organized patterning in hESCs. In response to BMP4, colonies reproducibly differentiated to an outer trophectoderm-like ring, an inner ectodermal circle and a ring of mesendoderm expressing primitive-streak markers in between. Fates were defined relative to the boundary with a fixed length scale: small colonies corresponded to the outer layers of larger ones. Inhibitory signals limited the range of BMP4 signaling to the colony edge and induced a gradient of Activin-Nodal signaling that patterned mesendodermal fates. These results demonstrate that the intrinsic tendency of stem cells to make patterns can be harnessed by controlling colony geometries and provide a quantitative assay for studying paracrine signaling in early development.
651 citations
TL;DR: Current understanding of the genetic architecture of ASD is reviewed and genetic evidence, neuropathology and studies in model systems with how they inform mechanistic models of ASD pathophysiology are integrated.
Abstract: Progress in understanding the genetic etiology of autism spectrum disorders (ASD) has fueled remarkable advances in our understanding of its potential neurobiological mechanisms. Yet, at the same time, these findings highlight extraordinary causal diversity and complexity at many levels ranging from molecules to circuits and emphasize the gaps in our current knowledge. Here we review current understanding of the genetic architecture of ASD and integrate genetic evidence, neuropathology and studies in model systems with how they inform mechanistic models of ASD pathophysiology. Despite the challenges, these advances provide a solid foundation for the development of rational, targeted molecular therapies.
650 citations
TL;DR: This Review examines how tissue barrier properties, parenchymal tissue function and multi-organ interactions can be recreated in organ-on-a-chip systems and applied for drug screening.
Abstract: Predicting the effects of drugs before human clinical trials is at the heart of drug screening and discovery processes. The cost of drug discovery is steadily increasing owing to the limited predictability of 2D cell culture and animal models. The convergence of microfabrication and tissue engineering gave rise to organ-on-a-chip technologies, which offer an alternative to conventional preclinical models for drug screening. Organ-on-a-chip devices can replicate key aspects of human physiology crucial for the understanding of drug effects, improving preclinical safety and efficacy testing. In this Review, we discuss how organ-on-a-chip technologies can recreate functions of organs, focusing on tissue barrier properties, parenchymal tissue function and multi-organ interactions, which are three key aspects of human physiology. Specific organ-on-a-chip systems are examined in terms of cell sources, functional hallmarks and available disease models. Finally, we highlight the challenges that need to be overcome for the clinical translation of organ-on-a-chip devices regarding materials, cellular fidelity, multiplexing, sensing, scalability and validation. Organ-on-a-chip devices can recreate key aspects of human physiology in vitro, offering an alternative to animal models for preclinical drug testing. This Review examines how tissue barrier properties, parenchymal tissue function and multi-organ interactions can be recreated in organ-on-a-chip systems and applied for drug screening.
624 citations
TL;DR: It is shown that HLOs are remarkably similar to human fetal lung based on global transcriptional profiles, suggesting that HL Os are an excellent model to study human lung development, maturation and disease.
Abstract: Cell behavior has traditionally been studied in the lab in two-dimensional situations, where cells are grown in thin layers on cell-culture dishes. However, most cells in the body exist in a three-dimensional environment as part of complex tissues and organs, and so researchers have been attempting to re-create these environments in the lab. To date, several such ‘organoids’ have been successfully generated, including models of the human intestine, stomach, brain and liver. These organoids can mimic the responses of real tissues and can be used to investigate how organs form, change with disease, and how they might respond to potential therapies. Here, Dye et al. developed a new three-dimensional model of the human lung by coaxing human stem cells to become specific types of cells that then formed complex tissues in a petri dish. To make these lung organoids, Dye et al. manipulated several of the signaling pathways that control the formation of organs during the development of animal embryos. First, the stem cells were instructed to form a type of tissue called endoderm, which is found in early embryos and gives rise to the lung, liver and other several other internal organs. Then, Dye et al. activated two important developmental pathways that are known to make endoderm form three-dimensional intestinal tissue. However, by inhibiting two other key developmental pathways at the same time, the endoderm became tissue that resembles the early lung found in embryos instead. This early lung-like tissue formed three-dimensional spherical structures as it developed. The next challenge was to make these structures develop into lung tissue. Dye et al. worked out a method to do this, which involved exposing the cells to additional proteins that are involved in lung development. The resulting lung organoids survived in laboratory cultures for over 100 days and developed into well-organized structures that contain many of the types of cells found in the lung. Further analysis revealed the gene activity in the lung organoids resembles that of the lung of a developing human fetus, suggesting that lung organoids grown in the dish are not fully mature. Dye et al.'s findings provide a new approach for creating human lung organoids in culture that may open up new avenues for investigating lung development and diseases.
619 citations
Cites background from "Cerebral organoids model human brai..."
...Several recent advances in generating 3-dimensional (3D) organ-like tissues, called ‘organoids’, have been reported (Meyer et al., 2011; Spence et al., 2011; Nakano et al., 2012; Takebe et al., 2013; Lancaster et al., 2013; McCracken et al., 2014)....
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TL;DR: Basic approaches to generate stem cell-based organoids, their advantages and limitations, and how bioengineering strategies can be used to steer the cell composition and their 3D organization within organoids to further enhance their utility in research and therapies are discussed.
606 citations
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TL;DR: Induction of pluripotent stem cells from mouse embryonic or adult fibroblasts by introducing four factors, Oct3/4, Sox2, c-Myc, and Klf4, under ES cell culture conditions is demonstrated and iPS cells, designated iPS, exhibit the morphology and growth properties of ES cells and express ES cell marker genes.
23,959 citations
TL;DR: It is concluded that intestinal cryptvillus units are self-organizing structures, which can be built from a single stem cell in the absence of a non-epithelial cellular niche.
Abstract: The intestinal epithelium is the most rapidly self-renewing tissue in adult mammals. We have recently demonstrated the presence of about six cycling Lgr5(+) stem cells at the bottoms of small-intestinal crypts. Here we describe the establishment of long-term culture conditions under which single crypts undergo multiple crypt fission events, while simultanously generating villus-like epithelial domains in which all differentiated cell types are present. Single sorted Lgr5(+) stem cells can also initiate these cryptvillus organoids. Tracing experiments indicate that the Lgr5(+) stem-cell hierarchy is maintained in organoids. We conclude that intestinal cryptvillus units are self-organizing structures, which can be built from a single stem cell in the absence of a non-epithelial cellular niche.
5,193 citations
TL;DR: iPS cells competent for germline chimaeras can be obtained from fibroblasts, but retroviral introduction of c-Myc should be avoided for clinical application.
Abstract: We have previously shown that pluripotent stem cells can be induced from mouse fibroblasts by retroviral introduction of Oct3/4 (also called Pou5f1), Sox2, c-Myc and Klf4, and subsequent selection for Fbx15 (also called Fbxo15) expression These induced pluripotent stem (iPS) cells (hereafter called Fbx15 iPS cells) are similar to embryonic stem (ES) cells in morphology, proliferation and teratoma formation; however, they are different with regards to gene expression and DNA methylation patterns, and fail to produce adult chimaeras Here we show that selection for Nanog expression results in germline-competent iPS cells with increased ES-cell-like gene expression and DNA methylation patterns compared with Fbx15 iPS cells The four transgenes (Oct3/4, Sox2, c-myc and Klf4) were strongly silenced in Nanog iPS cells We obtained adult chimaeras from seven Nanog iPS cell clones, with one clone being transmitted through the germ line to the next generation Approximately 20% of the offspring developed tumours attributable to reactivation of the c-myc transgene Thus, iPS cells competent for germline chimaeras can be obtained from fibroblasts, but retroviral introduction of c-Myc should be avoided for clinical application
4,371 citations
TL;DR: Application of a selective Rho-associated kinase (ROCK) inhibitor, Y-27632, to hES cells markedly diminishes dissociation-induced apoptosis, increases cloning efficiency and facilitates subcloning after gene transfer, and enables SFEB-cultured hES Cells to survive and differentiate into Bf1+ cortical and basal telencephalic progenitors.
Abstract: Poor survival of human embryonic stem (hES) cells after cell dissociation is an obstacle to research, hindering manipulations such as subcloning. Here we show that application of a selective Rho-associated kinase (ROCK) inhibitor1,2, Y-27632, to hES cells markedly diminishes dissociation-induced apoptosis, increases cloning efficiency (from ∼1% to ∼27%) and facilitates subcloning after gene transfer. Furthermore, dissociated hES cells treated with Y-27632 are protected from apoptosis even in serum-free suspension (SFEB) culture3 and form floating aggregates. We demonstrate that the protective ability of Y-27632 enables SFEB-cultured hES cells to survive and differentiate into Bf1+ cortical and basal telencephalic progenitors, as do SFEB-cultured mouse ES cells.
2,094 citations
TL;DR: In this paper, the authors discuss how these features change during development from neuroepithelial to radial glial cells, and how this transition affects cell fate and neurogenesis.
Abstract: During the development of the mammalian central nervous system, neural stem cells and their derivative progenitor cells generate neurons by asymmetric and symmetric divisions. The proliferation versus differentiation of these cells and the type of division are closely linked to their epithelial characteristics, notably, their apical-basal polarity and cell-cycle length. Here, we discuss how these features change during development from neuroepithelial to radial glial cells, and how this transition affects cell fate and neurogenesis.
1,743 citations