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Human adherent cortical organoids in a multi-well format.
In the growing diversity of human induced pluripotent stem cell (iPSC)-derived models of brain development, we present here a novel method that exhibits 3D cortical layer formation in a reproducible topography of minimal dimensions. The resulting adherent cortical organoids (ACOs) develop by self-organization after seeding frontal cortex-patterned iPSC-derived neural progenitor cells in 384-well plates during 8 weeks of differentiation. The organoids have stereotypical dimensions of 3 × 3 × 0.2 mm, contain multiple subtypes of neurons, astrocytes, and oligodendrocyte lineage cells, and are amenable to extended culture for at least 10 months. Longitudinal imaging revealed morphologically mature dendritic spines, axonal myelination, and robust neuronal activity. Moreover, ACOs compare favorably to existing free-floating brain organoid models on the basis of robust reproducibility in obtaining topographically standardized radial cortical structures and circumventing internal necrosis. Adherent human cortical organoids hold considerable potential for high-throughput drug discovery applications, neurotoxicological screening, and mechanistic pathophysiological studies of brain disorders.
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Micro-vacuolation in rat brains after long term administration of GABA-transaminase inhibitors. Comparison of effects of ethanolamine-O-sulphate and vigabatrin.
Two "suicide" inhibitors of GABA-aminotransferase which are known to raise the concentration of GABA in vivo and to have anti-convulsant properties, have been compared for the extent to which they produce micro-vacuoles in the brains of rats. The compounds gamma-vinyl-GABA (Vigabatrin) and ethanolamine-O-sulphate were administered orally for six months to rats at doses that produced the same increase in brain GABA levels. Micro-vacuolation was found to be present in the brains of animals treated with either compound but to be more severe in those treated with Vigabatrin. A quantitative assessment using computerised image analysis revealed that both the number of vacuoles, and the area occupied by them, was twice as high in the Vigabatrin treated animals as in those treated with ethanolamine-O-sulphate. This quantitative difference could be seen to be due to the fact that in the Vigabatrin treated animals the vacuoles extended into the white matter tracts between the cerebellar folia whereas in those animals treated with ethanolamine-O-sulphate it was confined to the roof nucleus.
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Role of immature choroid plexus in the pathology of model mice and human iPSC-derived organoids with autism spectrum disorder.
During gestation, the choroid plexus (ChP) produces protein-rich cerebrospinal fluid and matures prior to brain development. It is assumed that ChP dysfunction has a profound effect on developmental neuropsychiatric disorders, such as autism spectrum disorder (ASD). However, the mechanisms linking immature ChP to the onset of ASD remain unclear. Here, we find that ChP-specific CAMDI-knockout mice develop an immature ChP alongside decreased multiciliogenesis and expression of differentiation marker genes following disruption of the cerebrospinal fluid barrier. These mice exhibit ASD-like behaviors, including anxiety and impaired socialization. Additionally, the administration of metformin, an FDA-approved drug, before the social critical period achieves ChP maturation and restores social behaviors. Furthermore, both the ASD model mice and organoids derived from patients with ASD developed an immature ChP. These results propose the involvement of an immature ChP in the pathogenesis of ASD and suggest the targeting of functional maturation of the ChP as a therapeutic strategy for ASD.
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Altered ECM deposition and cell adhesion signaling in a human cortical organoid model of fragile X syndrome.
Fragile X Syndrome (FXS) is the most common inherited intellectual disability, and the most common monogenic cause of autism spectrum disorder (ASD). It is caused by epigenetic silencing of the FMR1 gene leading to the loss of FMRP, an RNA-binding protein that regulates local mRNA translation in neuronal dendrites, crucial for synapse development. Three-dimensional (3D) brain organoid models derived through in vitro differentiation of pluripotent stem cells offer a powerful tool to dissect the underlying mechanisms of neurodevelopmental disorders. Here, we generated human FXS and control organoids using isogenic human embryonic stem cell clones with and without the FXS mutation. Our results show that mature FXS cortical brain organoids can be derived by inhibiting the TGFβ and Wnt pathways. Moreover, expression analyses including immunofluorescence, qRT-PCR, proteomics and western blotting reveal altered levels of neuronal markers and ECM deposition along with modulated downstream signaling molecules. Interestingly, in silico analysis of proteomics revealed several altered pathways, such as cell adhesion, regulation of neurogenesis and cell cycle that are implicated in FXS. Collectively, our unique FXS-organoids derived from isogenic hESC lines may serve as a model for studying the pathology of FXS disorder and for developing therapeutical intervention.
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APOE deficiency impacts neural differentiation and cholesterol biosynthesis in human iPSC-derived cerebral organoids.
BACKGROUND: The apolipoprotein E (APOE) gene is the strongest genetic risk factor for Alzheimer's disease (AD); however, how it modulates brain homeostasis is not clear. The apoE protein is a major lipid carrier in the brain transporting lipids such as cholesterol among different brain cell types. METHODS: We generated three-dimensional (3-D) cerebral organoids from human parental iPSC lines and its isogenic APOE-deficient (APOE-/-) iPSC line. To elucidate the cell-type-specific effects of APOE deficiency in the cerebral organoids, we performed scRNA-seq in the parental and APOE-/- cerebral organoids at Day 90. RESULTS: We show that APOE deficiency in human iPSC-derived cerebral organoids impacts brain lipid homeostasis by modulating multiple cellular and molecular pathways. Molecular profiling through single-cell RNA sequencing revealed that APOE deficiency leads to changes in cellular composition of isogenic cerebral organoids likely by modulating the eukaryotic initiation factor 2 (EIF2) signaling pathway as these events were alleviated by the treatment of an integrated stress response inhibitor (ISRIB). APOE deletion also leads to activation of the Wnt/β-catenin signaling pathway with concomitant decrease of secreted frizzled-related protein 1 (SFRP1) expression in glia cells. Importantly, the critical role of apoE in cell-type-specific lipid homeostasis was observed upon APOE deletion in cerebral organoids with a specific upregulation of cholesterol biosynthesis in excitatory neurons and excessive lipid accumulation in astrocytes. Relevant to human AD, APOE4 cerebral organoids show altered neurogenesis and cholesterol metabolism compared to those with APOE3. CONCLUSIONS: Our work demonstrates critical roles of apoE in brain homeostasis and offers critical insights into the APOE4-related pathogenic mechanisms.
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Hallmark Molecular and Pathological Features of POLG Disease are Recapitulated in Cerebral Organoids.
In this research, a 3D brain organoid model is developed to study POLG-related encephalopathy, a mitochondrial disease stemming from POLG mutations. Induced pluripotent stem cells (iPSCs) derived from patients with these mutations is utilized to generate cortical organoids, which exhibited typical features of the diseases with POLG mutations, such as altered morphology, neuronal loss, and mitochondiral DNA (mtDNA) depletion. Significant dysregulation is also identified in pathways crucial for neuronal development and function, alongside upregulated NOTCH and JAK-STAT signaling pathways. Metformin treatment ameliorated many of these abnormalities, except for the persistent affliction of inhibitory dopamine-glutamate (DA GLU) neurons. This novel model effectively mirrors both the molecular and pathological attributes of diseases with POLG mutations, providing a valuable tool for mechanistic understanding and therapeutic screening for POLG-related disorders and other conditions characterized by compromised neuronal mtDNA maintenance and complex I deficiency.
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Generation of iPSC-derived human forebrain organoids assembling bilateral eye primordia.
Induced pluripotent stem cell-derived brain organoids enable the developmental complexities of the human brain to be deconstructed. During embryogenesis, optic vesicles (OVs), the eye primordium attached to the forebrain, develop from diencephalon. However, most 3D culturing methods generate either brain or retinal organoids individually. Here we describe a protocol to generate organoids with both forebrain entities, which we call OV-containing brain organoids (OVB organoids). In this protocol, we first induce neural differentiation (days 0-5) and collect neurospheres, which we culture in a neurosphere medium to initiate their patterning and further self-assembly (days 5-10). Then, upon transfer to spinner flasks containing OVB medium (days 10-30), neurospheres develop into forebrain organoids with one or two pigmented dots restricted to one pole, displaying forebrain entities of ventral and dorsal cortical progenitors and preoptic areas. Further long-term culture results in photosensitive OVB organoids constituting complementary cell types of OVs, including primitive corneal epithelial and lens-like cells, retinal pigment epithelia, retinal progenitor cells, axon-like projections and electrically active neuronal networks. OVB organoids provide a system to help dissect interorgan interactions between the OVs as sensory organs and the brain as a processing unit, and can help model early eye patterning defects, including congenital retinal dystrophy. To conduct the protocol, experience in sterile cell culture and maintenance of human induced pluripotent stem cells is essential; theoretical knowledge of brain development is advantageous. Furthermore, specialized expertise in 3D organoid culture and imaging for the analysis is needed.
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Human brain organoids to explore SARS-CoV-2-induced effects on the central nervous system.
Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019 (COVID-19). In less than three years, an estimated 600 million infections with SARS-CoV-2 occurred worldwide, resulting in a pandemic with tremendous impact especially on economic and health sectors. Initially considered a respiratory disease, COVID-19, along with its long-term sequelae (long-COVID) rather is a systemic disease. Neurological symptoms like dementia or encephalopathy were reported early during the pandemic as concomitants of the acute phase and as characteristics of long-COVID. An excessive inflammatory immune response is hypothesized to play a major role in this context. However, direct infection of neural cells may also contribute to the neurological aspects of (long)-COVID-19. To mainly explore such direct effects of SARS-CoV-2 on the central nervous system, human brain organoids provide a useful platform. Infecting these three-dimensional tissue cultures allows the study of viral neurotropism as well as of virus-induced effects on single cells or even the complex cellular network within the organoid. In this review, we summarize the experimental studies that used SARS-CoV-2-infected human brain organoids to unravel the complex nature of (long)-COVID-19-related neurological manifestations.
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Targeting PGC-1α axis rescues aberrant development from thyroid hormone defect in brain organoids.
Thyroid hormone (T3) deficiency during central nervous system development leads to severe and often incurable human pathologies, including intellectual disability and motor dysfunction. Using murine dorsal forebrain organoids, we showed that T3 is required to activate mitochondrial β-oxidation and OXPHOS biogenesis to sustain neuronal development, while its absence caused profound neurodevelopmental defects such as defective maturation, astrogliosis, and reduced spontaneous activity. Mechanistically, we identified the transcriptional coactivator PGC-1α as a central mediator of the T3 effect. Pharmacological inhibition of β-oxidation in T3-supplemented organoids recapitulated the T3-deficient phenotype, whereas Ppargc1a gene augmentation rescued neuronal development under T3-deprived conditions. Most importantly, pharmacological stimulation of the PGC-1α axis with Nicotinamide Riboside or Bezafibrate rescues mitochondrial bioenergetics and neuronal development, effectively correcting aberrant brain organoid maturation despite T3 deficiency. These findings reveal for the first time the role of T3 in supporting neurodevelopment via activation of mitochondrial β-oxidation and OXPHOS biogenesis, and identify the PGC-1α axis as a promising therapeutic avenue for otherwise intractable disorders linked to thyroid hormone deficiency.
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Modeling neuropsychiatric disorders using human induced pluripotent stem cells.
Neuropsychiatric disorders are complex disorders characterized by heterogeneous genetic variations, variable symptoms, and widespread changes in anatomical pathology. In the context of neuropsychiatric disorders, limited access to relevant tissue types presents challenges for understanding disease etiology and developing effective treatments. Induced pluripotent stem cells (iPSCs) reprogrammed from patient somatic cells offer an opportunity to recapitulate disease development in relevant cell types, and they provide novel approaches for understanding disease mechanisms and for development of effective treatments. Here we review recent progress and challenges in differentiation paradigms for generating disease-relevant cells and recent studies of neuropsychiatric disorders using human pluripotent stem cell (hPSC) models where cellular phenotypes linked to disease have been reported. The use of iPSC-based disease models holds great promise for understanding disease mechanisms and supporting discovery of effective treatments.