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Page 40 of 545-
Public Engagement With Brain Organoid Research and Application: Lessons From Genome Editing.
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3D Organoid Assay of the Impact of Infected Erythrocyte Adhesion on the Blood-Brain Barrier.
Mass sequestration of Plasmodium falciparum parasites in the brain microvasculature can lead to cerebral malaria (CM), characterized by inflammation, vessel occlusion, and brain swelling. To date, only single-cell-type, monolayer assays have been used to investigate the effect of infected erythrocytes (IEs) on the human blood-brain barrier (BBB) and the underlying parenchyma. Here we present a human-derived 3D model of the BBB comprised of endothelial cells, pericytes, and astrocytes in direct contact with each other. The organoids readily self-assemble and can easily be grown in 96-well plates, allowing for high-throughput analysis. These organoids allow for the assessment of parasite adhesion, and analysis of barrier function, and gross morphological changes in response to parasite exposure.
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Resolving organoid brain region identities by mapping single-cell genomic data to reference atlases.
Self-organizing tissues resembling brain structures generated from human stem cells offer exciting possibilities to study human brain development, disease, and evolution. These 3D models are complex and can contain cells at various stages of differentiation from different brain regions. Single-cell genomic methods provide powerful approaches to explore cell composition, differentiation trajectories, and genetic perturbations in brain organoid systems. However, it remains a major challenge to understand the heterogeneity observed within and between individual organoids. Here, we develop a set of computational tools (VoxHunt) to assess brain organoid patterning, developmental state, and cell identity through comparisons to spatial and single-cell transcriptome reference datasets. We use VoxHunt to characterize and visualize cell compositions using single-cell and bulk genomic data from multiple organoid protocols modeling different brain structures. VoxHunt will be useful to assess organoid engineering protocols and to annotate cell fates that emerge in organoids during genetic and environmental perturbation experiments.
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Generation of Blood Vascular Endothelial-Neural 3D Organoids by Serial Induction of Differentiation on Human iPSC-Derived Embryoid Bodies.
The 3D brain organoids have been widely used as a tool to study human brain development and disorders. Although angiogenesis and blood vascular endothelial cells play important roles in brain development and pathogenesis in neurological disorders, most 3D brain organoids lack inherent endothelial cells and need either the addition of differentiated endothelial cells or to be transplanted to animals to reconstitute such vascular structures. However, these approaches could miss the developmental interactions between angiogenesis and neurogenesis in the human brain. To reconstitute a 3D organoid mimicking the in vivo development of neural and vascular endothelial cells, we cultured iPSC-derived embryoid bodies and sequentially applied endothelial and neuronal induction media along with Matrigel embedding. The resulting 3D organoid consists of both neural cells and endothelial cells with vascular-like structures, as determined by immunostaining. With scRNA-Seq analysis, the organoid was confirmed to contain neural cell types similar to human brains, including a variety of excitatory and inhibitory neurons and glia. Furthermore, when compared with conventionally generated cerebral organoids without endothelial cells using RNA-Seq analysis, the vascular endothelial-containing neural organoids (EC-neural organoids) showed different gene profiles and favored angiogenesis and vasculogenesis. Of the differentially expressed genes, KRBA2 expression was found to be higher in neural cells and its inhibition by siRNA treatment resulted in decreased transcriptions of a variety of genes specific to neuronal differentiation but not genes specific to pluripotent stem cells such as OCT4. The EC-neural organoids also expressed receptors to SARS-CoV-2 at levels similar to human brains. This 3D EC-neural model provides a useful tool to study the interactions between vascular endothelial cells and neural cells in brain development and potentially for the study of neural infectious disorders where vascular endothelial cells are targets for infection and mediators for neural damage.
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A brain organoid/ALL coculture model reveals the AP-1 pathway as critically associated with CNS involvement of BCP-ALL.
Central nervous system (CNS) involvement remains a clinical hurdle in treating childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL). The disease mechanisms of CNS leukemia are primarily investigated using 2-dimensional cell culture and mouse models. Given the variations in cellular identity and architecture between the human and murine CNS, it becomes imperative to seek complementary models to study CNS leukemia. Here, we present a first-of-its-kind 3-dimensional coculture model combining human brain organoids and BCP-ALL cells. We noticed significantly higher engraftment of BCP-ALL cell lines and patient-derived xenograft (PDX) cells in cerebral organoids than non-ALL cells. To validate translatability between organoid coculture and in vivo murine models, we confirmed that targeting CNS leukemia-relevant pathways such as CD79a/Igα or C-X-C motif chemokine receptor 4-stromal cell-derived factor 1 reduced the invasion of BCP-ALL cells into organoids. RNA sequencing and functional validations of organoid-invading leukemia cells compared with the noninvaded fraction revealed significant upregulation of activator protein 1 (AP-1) transcription factor-complex members in organoid-invading cells. Moreover, we detected a significant enrichment of AP-1 pathway genes in PDX ALL cells recovered from the CNS compared with spleen blasts of mice that had received transplantation with TCF3::PBX1+ PDX cells, substantiating the role of AP-1 signaling in CNS disease. Accordingly, we found significantly higher levels of the AP-1 gene, jun proto-oncogene, in patients initially diagnosed as CNS-positive BCP-ALL compared with CNS-negative cases as well as CNS-relapse vs non-CNS-relapse cases in a cohort of 100 patients with BCP-ALL. Our results suggest CNS organoids as a novel model to investigate CNS involvement and identify the AP-1 pathway as a critical driver of CNS disease in BCP-ALL.
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Drug discovery in psychopharmacology: from 2D models to cerebral organoids .
Psychiatric disorders are a heterogeneous group of mental illnesses associated with a high social and economic burden on patients and society. The complex symptomatology of these disorders, coupled with our limited understanding of the structural and functional abnormalities affecting the brains of neuropsychiatric patients, has made it difficult to develop effective medical treatment strategies. With the advent of reprogramming technologies and recent developments in induced pluripotent stem (iPS) cell-based protocols for differentiation into defined neuronal cultures and 3-dimensional cerebral organoids, a new era of preclinical disease modeling has begun which could revolutionize drug discovery in psychiatry. This review provides an overview of iPS cell-based disease models in psychiatry and how these models contribute to our understanding of pharmacological drug action. We also propose a refined iPSC-based drug discovery pipeline, ranging from cell-based stratification of patients through improved screening and validation steps to more precise psychopharmacology. .
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Derivation of Functional Human Astrocytes from Cerebral Organoids.
Astrocytes play a critical role in the development and homeostasis of the central nervous system (CNS). Astrocyte dysfunction results in several neurological and degenerative diseases. However, a major challenge to our understanding of astrocyte physiology and pathology is the restriction of studies to animal models, human post-mortem brain tissues, or samples obtained from invasive surgical procedures. Here, we report a protocol to generate human functional astrocytes from cerebral organoids derived from human pluripotent stem cells. The cellular isolation of cerebral organoids yielded cells that were morphologically and functionally like astrocytes. Immunolabelling and proteomic assays revealed that human organoid-derived astrocytes express the main astrocytic molecular markers, including glutamate transporters, specific enzymes and cytoskeletal proteins. We found that organoid-derived astrocytes strongly supported neuronal survival and neurite outgrowth and responded to ATP through transient calcium wave elevations, which are hallmarks of astrocyte physiology. Additionally, these astrocytes presented similar functional pathways to those isolated from adult human cortex by surgical procedures. This is the first study to provide proteomic and functional analyses of astrocytes isolated from human cerebral organoids. The isolation of these astrocytes holds great potential for the investigation of developmental and evolutionary features of the human brain and provides a useful approach to drug screening and neurodegenerative disease modelling.
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Multiscale Comparative Analyses of OVB-Organoids and Cerebral Organoids.
Organoid technology is critical for studying human brain development, but existing single-organoid culture systems fail to simulate inter-organ interactions (e.g., optic vesicle-brain) in embryogenesis. This study aimed to establish a more comprehensive in vitro model for early neurodevelopment. We established standardized protocols for cerebral organoids and optic vesicle-containing brain organoids (OVB-organoids), and performed multiscale analyses using immunofluorescence and transcriptomics to compare the two models. Key differences in cellular composition, structure, function and development were found; OVB-organoids better simulated early retinal development, visual-related structures/functions, with specific VSX2 expression and consistent transcriptomic profiles. OVB-organoids are an improved model for early neurodevelopment, providing a reliable basis for exploring eye-brain coordinated development mechanisms and having broad applications in developmental biology, disease research and personalized healthcare.
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The Evolving Role of Induced Pluripotent Stem Cells and Cerebral Organoids in Treating and Modeling Neurosurgical Diseases.
Over the past decade, the use of induced pluripotent stem cells (IPSCs), as both direct therapeutics and building blocks for 3D in vitro models, has exhibited exciting potential in both helping to elucidate pathogenic mechanisms and treating diseases relevant to neurosurgery. Transplantation of IPSCs is being studied in neurological injuries and diseases, such as spinal cord injury and Parkinson's disease, whose clinical manifestations stem from underlying neuronal and/or axonal degeneration. Both animal models and clinical trials have shown that IPSCs have the ability to regenerate damaged neural tissue. Such evidence makes IPSCs a potentially promising therapeutic modality for patients who suffer from these neurological injuries/diseases. In addition, the cerebral organoid, a 3D assembly of IPSC aggregates that develops heterogeneous brain regions, has become the first in vitro model to closely recapitulate the complexity of the brain extracellular matrix, a 3-dimensional network of molecules that structurally and biochemically support neighboring cells. Cerebral organoids have become an exciting prospect for modeling and testing drug susceptibility of brain tumors, such as glioblastoma and metastatic brain cancer. As patient-derived organoid models are becoming more faithful to the brain, they are becoming an increasingly accurate substitute for patient clinical trials; such patient-less trials would protect the patient from potentially ineffective drugs, and speed up trial results and optimize cost. In this review, we aim to describe the role of IPSCs and cerebral organoids in treating and modeling diseases that are relevant to neurosurgery.
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Structural Analysis of Cerebral Organoids Using Confocal Microscopy and Transmission/Scanning Electron Microscopy.
Cerebral organoid cultures from human-induced pluripotent stem cells are widely used to study complex human brain development; however, there is still limited ultrastructural information regarding the development. In this study, we examined the structural details of cerebral organoids using various microscopy techniques. Two protocols were chosen as representative methods for the development of brain organoids: the classic whole-cerebral organoid (Whole-CO) culture technique, and the air-liquid interface-cerebral organoid (ALI-CO) culture technique. Immunostained confocal laser scanning microscopy (CLSM) revealed the formation of the CTIP2- and TBR1-positive cortical deep layer on days 90 and 150, depending on the developmental progress of both methods. Furthermore, the presence of astrocytes and oligodendrocytes was verified through immunostained CLSM utilizing two-dimensional and three-dimensional reconstruction images after a 150-day period. Transmission electron microscopy analysis revealed nanometer-resolution details of the cellular organelles and neuron-specific structures including synapses and myelin. Large-area scanning electron microscopy confirmed the well-developed neuronal connectivity from each culture method on day 150. Using those microscopy techniques, we clearly showed significant details within two representative culture protocols, the Whole-CO and ALI-CO culture methods. These multi-level images provide ultrastructural insight into the features of cerebral organoids depending on the developmental stage.