Huntington's disease (HD) is a devastating, autosomal‐dominant neurodegenerative disease, for which there are currently no disease‐modifying therapies. Clinical trials to replace the damaged striatal ...medium spiny neurons (MSNs) have been attempted in the past two decades but have met with only limited success. In this study, we investigated whether a clonal, conditionally immortalized neural stem cell line (CTX0E03), which has already shown safety and signals of efficacy in chronic ischemic stroke patients, could rescue deficits seen in an animal model of HD. After CTX0E03 transplantation into the quinolinic acid‐lesioned rat model of HD, behavioral changes were measured using the rotarod, stepping, and staircase tests. In vivo differentiation and neuronal connections of the transplanted CTX0E03 cells were evaluated with immunohistochemical staining and retrograde tracing with Fluoro‐Gold. We found that transplantation of CTX0E03 gave rise to a significant behavioral improvement compared with the sham‐ or fibroblast‐transplanted group. Transplanted CTX0E03 formed MSNs (DARPP‐32) and GABAergic neurons (GABA, GAD65/67) with BDNF expression in the striatum, while cortically transplanted cells formed Tbr1‐positive neurons. Using a retrograde label, we also found stable engraftment and connection of the transplanted cells with host brain tissues. CTX0E03 transplantation also reduced glial scar formation and inflammation, as well as increasing endogenous neurogenesis and angiogenesis. Overall, our results demonstrate that CTX0E03, a clinical‐grade neural stem cell line, is effective for preclinical test in HD, and, therefore, will be useful for clinical development in the treatment of HD patients.
Implantation of the clinical‐grade human neural stem cell line, CTX0E03, leads to behavioral improvement, as well as neuronal differentiation and tissue repair in the quinolinic acid‐lesioned rodent model of Huntington's disease over the period of 12 weeks following implantation.
Background and Purpose
The discovery of new bromo‐ and extra‐terminal inhibitors presents new drugs to treat osteoarthritis (OA).
Experimental Approach
The new drug, BBC0403, was identified in the ...DNA‐encoded library screening system by searching for compounds that target BRD (bromodomain‐containing) proteins. The binding force with BRD proteins was evaluated using time‐resolved fluorescence energy transfer (TR‐FRET) and binding kinetics assays. Subsequently, in vitro and ex vivo analyses demonstrated the effects of the BRD2 inhibitor, BBC0403, on OA. For animal experiments, medial meniscus destabilization was performed to create a 12‐week‐old male C57BL/6 mouse model, and intra‐articular (i.a.) injections were administered. Histological and immunohistochemical analyses were then performed. The underlying mechanism was confirmed by gene set enrichment analysis (GSEA) using RNA‐seq.
Key Results
TR‐FRET and binding kinetics assays revealed that BBC0403 exhibited higher binding specificity for BRD2 compared to BRD3 and BRD4. The anti‐OA effects of BBC0403 were tested at concentrations of 5, 10 and 20 μM (no cell toxicity in the range tested). The expression of catabolic factors, prostaglandin E2 (PGE2) production and extracellular matrix (ECM) degradation was reduced. Additionally, the i.a. injection of BBC0403 prevented OA cartilage degradation in mice. Finally, BBC0403 was demonstrated to suppress NF‐κB and MAPK signalling pathways.
Conclusion and Implications
This study demonstrated that BBC0403 is a novel BRD2‐specific inhibitor and a potential i.a.‐injectable therapeutic agent to treat OA.
Human brain organoid systems offer unprecedented opportunities to investigate both neurodevelopmental and neurological disease. Single-cell-based transcriptomics or epigenomics have dissected the ...cellular and molecular heterogeneity in the brain organoids, revealing a complex organization. Similar but distinct protocols from different labs have been applied to generate brain organoids, providing a large resource to perform a comparative analysis of brain developmental processes. Here, we take a systematic approach to compare the single-cell transcriptomes of various human cortical brain organoids together with fetal brain to define the identity of specific cell types and differentiation routes in each method. Importantly, we identify unique developmental programs in each protocol compared to fetal brain, which will be a critical benchmark for the utility of human brain organoids in the future.
Display omitted
•Systematic comparison to uncover unique features in each brain organoid protocol•Similar cell compositions across protocols•Distinct preference of differentiation trajectories across protocols•Generation of interneurons from human cortical organoids
Tanaka et al. report integrative analyses of single-cell RNA-seq for human brain organoids derived from different protocols. They find a unique preference of cell differentiation routes across protocols and provide a benchmark for the use and the improvement of human brain organoids.
Microglia play a role in the emergence and preservation of a healthy brain microenvironment. Dysfunction of microglia has been associated with neurodevelopmental and neurodegenerative disorders. ...Investigating the function of human microglia in health and disease has been challenging due to the limited models of the human brain available. Here, we develop a method to generate functional microglia in human cortical organoids (hCOs) from human embryonic stem cells (hESCs). We apply this system to study the role of microglia during inflammation induced by amyloid-β (Aβ). The overexpression of the myeloid-specific transcription factor PU.1 generates microglia-like cells in hCOs, producing mhCOs (microglia-containing hCOs), that we engraft in the mouse brain. Single-cell transcriptomics reveals that mhCOs acquire a microglia cell cluster with an intact complement and chemokine system. Functionally, microglia in mhCOs protect parenchyma from cellular and molecular damage caused by Aβ. Furthermore, in mhCOs, we observed reduced expression of Aβ-induced expression of genes associated with apoptosis, ferroptosis, and Alzheimer's disease (AD) stage III. Finally, we assess the function of AD-associated genes highly expressed in microglia in response to Aβ using pooled CRISPRi coupled with single-cell RNA sequencing in mhCOs. In summary, we provide a protocol to generate mhCOs that can be used in fundamental and translational studies as a model to investigate the role of microglia in neurodevelopmental and neurodegenerative disorders.
Brain organoids, three-dimensional neural cultures recapitulating the spatiotemporal organization and function of the brain in a dish, offer unique opportunities for investigating the human brain ...development and diseases. To model distinct parts of the brain, various region-specific human brain organoids have been developed. In this article, we review current approaches to produce human region-specific brain organoids, developed through the endeavor of many researchers. We highlight the applications of human region-specific brain organoids, especially in reconstructing regional interactions in the brain through organoid fusion. We also outline the existing challenges to drive forward further the brain organoid technology and its applications for future studies.
Along with emergence of the organoids, their application in biomedical research has been currently one of the most fascinating themes. For the past few years, scientists have made significant ...contributions to deriving organoids representing the whole brain and specific brain regions. Coupled with somatic cell reprogramming and CRISPR/Cas9 editing, the organoid technologies were applied for disease modeling and drug screening. The methods to develop organoids further improved for rapid and efficient generation of cerebral organoids. Additionally, refining the methods to develop the regionally specified brain organoids enabled the investigation of development and interaction of the specific brain regions. Recent studies started resolving the issue in the lack of non-neuroectodermal cells in brain organoids, including vascular endothelial cells and microglia, which play fundamental roles in neurodevelopment and are involved in the pathophysiology of acute and chronic neural disorders. In this review, we highlight recent advances of neuronal organoid technologies, focusing on the region-specific brain organoids and complementation with endothelial cells and microglia, and discuss their potential applications to neuronal diseases.
Organoid techniques provide unique platforms to model brain development and neurological disorders. Whereas several methods for recapitulating corticogenesis have been described, a system modeling ...human medial ganglionic eminence (MGE) development, a critical ventral brain domain producing cortical interneurons and related lineages, has been lacking until recently. Here, we describe the generation of MGE and cortex-specific organoids from human pluripotent stem cells that recapitulate the development of MGE and cortex domains, respectively. Population and single-cell RNA sequencing (RNA-seq) profiling combined with bulk assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) analyses revealed transcriptional and chromatin accessibility dynamics and lineage relationships during MGE and cortical organoid development. Furthermore, MGE and cortical organoids generated physiologically functional neurons and neuronal networks. Finally, fusing region-specific organoids followed by live imaging enabled analysis of human interneuron migration and integration. Together, our study provides a platform for generating domain-specific brain organoids and modeling human interneuron migration and offers deeper insight into molecular dynamics during human brain development.
Display omitted
•hMGEOs and hCOs recapitulate human brain organization and fetal brain transcriptomes•Transcriptome and chromatin accessibility distinguish hMGEOs and hCOs•hMGEOs and hCOs display activity-dependent and synchronized calcium oscillations•Interneurons migrate from hMGEOs and functionally integrate in hCOs
Xiang and colleagues report a method for generating human medial ganglionic eminence (MGE)-like organoids (hMGEOs) and cortical-like organoids (hCOs), which resemble the developing human MGE and cortex, respectively. By fusing hMGEOs and hCOs, they establish a 3D model to investigate human interneuron migration.
In this issue of Cell Stem Cell, Jin et al. report that human Down syndrome microglia exhibit enhanced synaptic engulfment and accelerated tau-induced cellular senescence in human-mouse chimeric ...brains. They show that inhibiting interferon signaling rescues both developmental and tau-associated phenotypes, rendering it a potential therapeutic target for Down syndrome.
In this issue of Cell Stem Cell, Jin et al. report that human Down syndrome microglia exhibit enhanced synaptic engulfment and accelerated tau-induced cellular senescence in human-mouse chimeric brains. They show that inhibiting interferon signaling rescues both developmental and tau-associated phenotypes, rendering it a potential therapeutic target for Down syndrome.
PDF
