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Extracellular vesicle profiling reveals novel autism signatures in patient-derived forebrain organoids.
Autism Spectrum Disorder (ASD) affects 1 percent of the world's population with an increased prevalence of 178 percent since 2000. Although altered synaptic function putatively accounts for many of the abnormalities seen in ASD, the specific molecular mechanisms underlying this disorder remain poorly defined. A growing body of evidence suggests that extracellular vesicles (EVs), specifically exosomes, play a critical role in cellular communication within the brain. While they have been implicated in various types of diseases from cancer to neurodegeneration, their involvement in ASD remains largely unexplored. In this study, we utilized patient-derived cortical organoid models to characterize EVs secreted by human three-dimensional (3D) tissue and defined their cargo. Our study reports, for the first time, alterations in ASD organoid-derived EVs in comparison to healthy control cortical EVs. By utilizing small RNA sequencing, proteomics, nanoparticle tracking and microscopy, we provide a comprehensive characterization of the cargo carried by EVs secreted from human 3D forebrain models. Our findings reveal substantial differences both in the RNA and protein content of ASD-derived EVs, providing insight into disease mechanisms as well as highlighting the potential of exosome-based diagnostics and therapies for ASD.
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AAV-DJ enables efficient, function-preserving neuronal transduction for circuit interrogation in human cortical and thalamic organoids.
Neural organoids provide tractable models of human brain development, function, and disease, but adeno-associated viral vector (AAV)-based gene delivery is limited by inefficient transduction and insufficient comparative evaluation of the natural and engineered capsids. Here, we evaluated seven AAV capsids (AAV-2, -6, -9, -DJ, -2-retro, -PHP.eB, and -Cap-Mac) for transduction efficiency, cell type tropism, cytotoxicity, and functional integrity in human cortical and thalamic organoids. AAV-Cap-Mac demonstrated the highest transduction efficiency, with broad cellular tropism, but caused cytotoxicity and decreased neuronal activity. By contrast, AAV-DJ yielded efficient neuronal transduction, with preserved calcium dynamics and minimal cytotoxicity, which enabled rabies virus-based circuit tracing and all-optical physiology. Our findings reveal a capsid-dependent trade-off between transduction efficiency and functional integrity and identify AAV-DJ as an optimal serotype for robust gene delivery and physiological interrogation in organoid-based neuroscience. Combining AAV-DJ with emerging molecular and circuit-level technologies in organoids should facilitate mechanistic and translational studies of the human brain.
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Human myelinated brain organoids with integrated microglia as a model for myelin repair and remyelinating therapies.
Oligodendrocytes, the myelinating cells of the central nervous system (CNS), are essential for the formation of myelin sheaths and pivotal for maintaining axonal integrity and conduction. Disruption of these cells and the myelin sheaths they produce is a hallmark of demyelinating conditions like multiple sclerosis or those resulting from certain drug side effects, leading to profound neurological impairments. In this study, we created a human brain organoid comprising neurons, astrocytes, and myelinating oligodendrocytes. By integrating induced pluripotent stem cell-derived microglia, we endowed these myelinated human brain organoids (MHBOs) with immune characteristics. MHBOs with microglia (MHBOs +MG) enabled the investigation of demyelination and remyelination-a process in which myelin sheaths are regenerated-in a human context. After toxin-induced demyelination, we observed a reduction in myelin followed by subsequent self-driven remyelination. Proteomic and transcriptomic analyses provided a molecular signature of demyelination and myelin recovery indicating a central role for microglia in the remyelination process. Furthermore, the application of the pro-remyelinating compounds clemastine, XAV939, and BQ3020 further enhanced remyelination in MHBOs +MG but was ineffective in the absence of microglia. Cross-validation of our findings in mouse cerebellar slice cultures confirmed that the pro-remyelinating compounds were effective ex vivo, suggesting the translational potential of our MHBOs +MG model.
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A Human-specific Protein Regulated by Alternative Polyadenylation Shapes Uniqueness of Human Brain Development.
Although new genes and regulatory events have been linked to the uniqueness of human brain development, it is unknown whether alternative polyadenylation (APA) also contributes to shaping this key feature that differentiates humans from other species. Here, we present an atlas of APAs of the human brain and identified 161 development-related, open-reading-frame-disrupting APAs associated with the dynamic translation of protein products. Among the genes affected by these events, we identified ZNF271P, which encodes a human-specific protein when using the distal polyadenylation site, a site that preferentially occurs during early brain development. The cortical organoids derived from ZNF271P-knockout human embryonic stem cells seemed to exhibit accelerated development and maturation, resulting in a significant decrease in organoid size, implicating that ZNF271P is involved in features unique to human brain development. We thus highlight APAs as new regulators in shaping the unique aspects of human brain development.
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Protocol for generating reproducible miniaturized controlled midbrain organoids.
Here, we present a protocol for generating miniaturized controlled midbrain organoids (MiCOs) of reproducible size and cellular composition, without a necrotic center. We describe steps for maintaining and passaging human pluripotent stem cells, generating MiCOs using AggreWell™400, and maintaining them in an EB-Disk360on an orbital shaker, eliminating the need for Matrigel or a spinner flask and preventing organoid fusion. We then detail organoid collection for different endpoint analysis. This protocol is suitable for compound screening and disease modeling studies.
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Modeling HIV-1 neuropathogenesis using three-dimensional human brain organoids (hBORGs) with HIV-1 infected microglia.
HIV-1 associated neurocognitive disorder (HAND) is characterized by neuroinflammation and glial activation that, together with the release of viral proteins, trigger a pathogenic cascade resulting in synaptodendritic damage and neurodegeneration that lead to cognitive impairment. However, the molecular events underlying HIV neuropathogenesis remain elusive, mainly due to lack of brain-representative experimental systems to study HIV-CNS pathology. To fill this gap, we developed a three-dimensional (3D) human brain organoid (hBORG) model containing major cell types important for HIV-1 neuropathogenesis; neurons and astrocytes along with incorporation of HIV-infected microglia. Both infected and uninfected microglia infiltrated into hBORGs resulting in a triculture system (MG-hBORG) that mirrors the multicellular network observed in HIV-infected human brain. Moreover, the MG-hBORG model supported productive viral infection and exhibited increased inflammatory response by HIV-infected MG-hBORGs, releasing tumor necrosis factor (TNF-α) and interleukin-1 (IL-1β) and thereby mimicking the chronic neuroinflammatory environment observed in HIV-infected individuals. This model offers great promise for basic understanding of how HIV-1 infection alters the CNS compartment and induces pathological changes, paving the way for discovery of biomarkers and new therapeutic targets.
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[Construction and mechanisms of D-galactose-induced blood-brain barrier organoid aging model].
OBJECTIVE: To establish a D-galactose-induced aging model of the blood-brain barrier(BBB) with organoid technology and explore the pathophysiological mechanisms of BBB aging. METHODS: A BBB model was constructed on an organ-on-a-chip using human cerebral microvascular endothelial cells(hCMEC/D3), followed by D-galactose exposure to induce aging. The model was evaluated by measuring transendothelial electrical resistance(TEER), apparent permeability coefficient(Papp) of fluorescein, β-galactosidase staining, live/dead cell staining, lactate dehydrogenase(LDH) activity, and reactive oxygen species(ROS) levels. The expression of tight junction proteins(ZO-1, Occludin), senescence-associated gene(p53), and anti-inflammatory genes(HO-1, Nrf2) was assessed using RT-qPCR to characterize aging features. RESULTS: The optimal concentration for inducing BBB organoid aging was 50 mg/mL D-galactose. The model group significantly reduced TEER((19.46±0.98)Ω·cm~2 vs. (22.07±0.21)Ω·cm~2, P<0.05), increased Papp of fluorescein((1.08±0.02)×10~(-4 )cm/s vs. (4.39±0.01)×10~(-5 )cm/s, P<0.05), elevated β-galactosidase-positive cells, decreased live cells, increased dead cells, and increased LDH release and ROS levels. RT-qPCR analysis showed downregulation of ZO-1 and Occludin, along with upregulation of p53, HO-1, and Nrf2. CONCLUSION: D-galactose induced aging-associated damage in the BBB organoid model, providing a reliable in vitro biomimetic platform for studying BBB aging mechanisms and potential therapeutic interventions for neurodegenerative diseases. This model contributes to the understanding of the pathophysiological processes underlying neurological disorders.
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Human neural organoid microphysiological systems show the building blocks necessary for basic learning and memory.
Brain Microphysiological Systems, including neural organoids derived from human induced pluripotent stem cells, offer a unique lens to study the intricate workings of the human brain. This paper investigates the foundational elements of learning and memory in neural organoids by quantifying immediate early gene expression in response to chemical modulation, input-specific short- and long-term synaptic plasticity, neuronal network dynamics, connectivity, and criticality to demonstrate the utility of these organoids in basic science research. Neural organoids showed synapse formation, glutamatergic and GABAergic receptor expression, immediate early gene expression basally and evoked, functional connectivity, criticality, and synaptic plasticity in response to theta-burst stimulation. In addition, pharmacological interventions on GABAergic and glutamatergic receptors and input-specific theta-burst stimulation further shed light on the capacity of neural organoids to mirror synaptic modulation, specifically short- and long-term potentiation and depression, demonstrating their potential as tools for studying neurophysiological and neurological processes and informing therapeutic strategies for diseases.
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Ataxia Telangiectasia patient-derived neuronal and brain organoid models reveal mitochondrial dysfunction and oxidative stress.
Ataxia Telangiectasia (AT) is a rare disorder caused by mutations in the ATM gene and results in progressive neurodegeneration for reasons that remain poorly understood. In addition to its central role in nuclear DNA repair, ATM operates outside the nucleus to regulate metabolism, redox homeostasis and mitochondrial function. However, a systematic investigation into how and when loss of ATM affects these parameters in relevant human neuronal models of AT was lacking. We therefore used cortical neurons and brain organoids from AT-patient iPSC and gene corrected isogenic controls to reveal levels of mitochondrial dysfunction, oxidative stress, and senescence that vary with developmental maturity. Transcriptome analyses identified disruptions in regulatory networks related to mitochondrial function and maintenance, including alterations in the PARP/SIRT signalling axis and dysregulation of key mitophagy and mitochondrial fission-fusion processes. We further show that antioxidants reduce ROS and restore neurite branching in AT neuronal cultures, and ameliorate impaired neuronal activity in AT brain organoids. We conclude that progressive mitochondrial dysfunction and aberrant ROS production are important contributors to neurodegeneration in AT and are strongly linked to ATM's role in mitochondrial homeostasis regulation.
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Single-cell multi-omic atlas and morphogen screening informs midbrain and hindbrain organoid engineering.
Patterning of the neural tube establishes midbrain and hindbrain structures that coordinate motor movement, process sensory input and integrate cognitive functions. Cellular impairment within these structures underlies diverse neurological disorders, and in vitro organoid models promise inroads to understanding development and modeling disease. Here, we use paired single-cell transcriptome and accessible chromatin sequencing to map cell composition and regulatory mechanisms in organoid models of midbrain and hindbrain. We find that existing midbrain organoid protocols generate ventral and dorsal cell types, covering regions including floor plate, dorsal and ventral midbrain and adjacent hindbrain regions. Gene regulatory network inference and transcription factor perturbation resolve mechanisms underlying neuronal differentiation. A single-cell multiplexed patterning screen identifies morphogen concentrations that expand existing organoid models, including conditions generating medulla glycinergic neurons and cerebellum glutamatergic subtypes. Together, the multi-omic atlas and morphogen screen reveal morphogen-regulon relationships guiding region-specific progenitor differentiation towards diverse neuron types of the posterior brain.