Midbrain-like Organoids from Human Pluripotent Stem Cells Contain Functional Dopaminergic and Neuromelanin-Producing Neurons

Design of neural organoids engineered by mechanical forces

Neural organoids consist of three-dimensional tissue derived from pluripotent stem cells that could recapitulate key features of the human brain. During the past decade, organoid technology has evolved in the field of human brain science by increasing the quality and applicability of its products. Among them, a novel approach involving the design of neural organoids engineered by mechanical forces has emerged. This review describes previous approaches for the generation of neural organoids, the engineering of neural organoids by mechanical forces, and future challenges for the application of mechanical forces in the design of neural organoids.

Construction of human 3D striato-nigral assembloids to recapitulate medium spiny neuronal projection defects in Huntington's disease

The striato-nigral (Str-SN) circuit is composed of medium spiny neuronal projections that are mainly sent from the striatum to the midbrain substantial nigra (SN), which is essential for regulating motor behaviors. Dysfunction of the Str-SN circuitry may cause a series of motor disabilities that are associated with neurodegenerative disorders, such as Huntington's disease (HD). Although the etiology of HD is known as abnormally expanded CAG repeats of the huntingtin gene, treatment of HD remains tremendously challenging. One possible reason is the lack of effective HD model that resembles Str-SN circuitry deficits for pharmacological studies. Here, we first differentiated striatum-like organoids from human pluripotent stem cells (hPSCs), containing functional medium spiny neurons (MSNs). We then generated 3D Str-SN assembloids by assembling striatum-like organoids with midbrain SN-like organoids. With AAV-hSYN-GFP-mediated viral tracing, extensive MSN projections from the striatum to the SN are established, which formed synaptic connection with GABAergic neurons in SN organoids and showed the optically evoked inhibitory postsynaptic currents and electronic field potentials by labeling the striatum-like organoids with optogenetic virus. Furthermore, these Str-SN assembloids exhibited enhanced calcium activity compared to that of individual striatal organoids. Importantly, we further demonstrated the reciprocal projection defects in HD iPSC-derived assembloids, which could be ameliorated by treatment of brain-derived neurotrophic factor. Taken together, these findings suggest that Str-SN assembloids could be used for identifying MSN projection defects and could be applied as potential drug test platforms for HD.

Multiscale engineering of brain organoids for disease modeling

Brain organoids hold great potential for modeling human brain development and pathogenesis. They recapitulate certain aspects of the transcriptional trajectory, cellular diversity, tissue architecture and functions of the developing brain. In this review, we explore the engineering strategies to control the molecular-, cellular- and tissue-level inputs to achieve high-fidelity brain organoids. We review the application of brain organoids in neural disorder modeling and emerging bioengineering methods to improve data collection and feature extraction at multiscale. The integration of multiscale engineering strategies and analytical methods has significant potential to advance insight into neurological disorders and accelerate drug development.

Midbrain organoids for Parkinson's disease (PD) - A powerful tool to understand the disease pathogenesis

Brain Organiods (BOs) are a promising technique for researching disease progression in the human brain. These organoids, which are produced from human induced pluripotent stem cells (HiPSCs), can construct themselves into structured frameworks. In the context of Parkinson's disease (PD), recent advancements have been made in the development of Midbrain organoids (MBOs) models that consider key pathophysiological mechanisms such as alpha-synuclein (α-Syn), Lewy bodies, dopamine loss, and microglia activation. However, there are limitations to the current use of BOs in disease modelling and drug discovery, such as the lack of vascularization, long-term differentiation, and absence of glial cells. To address these limitations, researchers have proposed the use of spinning bioreactors to improve oxygen and nutrient perfusion. Modelling PD utilising modern experimental in vitro models is a valuable tool for studying disease mechanisms and elucidating previously unknown features of PD. In this paper, we exclusively review the unique methods available for cultivating MBOs using a pumping system that mimics the circulatory system. This mechanism may aid in delivering the required amount of oxygen and nutrients to all areas of the organoids, preventing cell death, and allowing for long-term culture and using co-culturing techniques for developing glial cell in BOs. Furthermore, we emphasise some of the significant discoveries about the BOs and the potential challenges of using BOs will be discussed.

Investigating the neurobiology of maternal opioid use disorder and prenatal opioid exposure using brain organoid technology

Over the past two decades, Opioid Use Disorder (OUD) among pregnant women has become a major global public health concern. OUD has been characterized as a problematic pattern of opioid use despite adverse physical, psychological, behavioral, and or social consequences. Due to the relapsing-remitting nature of this disorder, pregnant mothers are chronically exposed to exogenous opioids, resulting in adverse neurological and neuropsychiatric outcomes. Collateral fetal exposure to opioids also precipitates severe neurodevelopmental and neurocognitive sequelae. At present, much of what is known regarding the neurobiological consequences of OUD and prenatal opioid exposure (POE) has been derived from preclinical studies in animal models and postnatal or postmortem investigations in humans. However, species-specific differences in brain development, variations in subject age/health/background, and disparities in sample collection or storage have complicated the interpretation of findings produced by these explorations. The ethical or logistical inaccessibility of human fetal brain tissue has also limited direct examinations of prenatal drug effects. To circumvent these confounding factors, recent groups have begun employing induced pluripotent stem cell (iPSC)-derived brain organoid technology, which provides access to key aspects of cellular and molecular brain development, structure, and function in vitro. In this review, we endeavor to encapsulate the advancements in brain organoid culture that have enabled scientists to model and dissect the neural underpinnings and effects of OUD and POE. We hope not only to emphasize the utility of brain organoids for investigating these conditions, but also to highlight opportunities for further technical and conceptual progress. Although the application of brain organoids to this critical field of research is still in its nascent stages, understanding the neurobiology of OUD and POE via this modality will provide critical insights for improving maternal and fetal outcomes.

Development of Midbrain Dopaminergic Neurons and the Advantage of Using hiPSCs as a Model System to Study Parkinson's Disease

Midbrain dopaminergic (mDA) neurons are significantly impaired in patients inflicted with Parkinson's disease (PD), subsequently affecting a variety of motor functions. There are four pathways through which dopamine elicits its function, namely, nigrostriatal, mesolimbic, mesocortical and tuberoinfundibular dopamine pathways. SHH and Wnt signalling pathways in association with favourable expression of a variety of genes, promotes the development and differentiation of mDA neurons in the brain. However, there is a knowledge gap regarding the complex signalling pathways involved in development of mDA neurons. hiPSC models have been acclaimed to be effective in generating complex disease phenotypes. These models mimic the microenvironment found in vivo thus ensuring maximum reliability. Further, a variety of therapeutic compounds can be screened using hiPSCs since they can be used to generate neurons that could carry an array of mutations associated with both familial and sporadic PD. Thus, culturing hiPSCs to study gene expression and dysregulation of cellular processes associated with PD can be useful in developing targeted therapies that will be a step towards halting disease progression.

RosetteArray Platform for Quantitative High-Throughput Screening of Human Neurodevelopmental Risk

Neural organoids have revolutionized how human neurodevelopmental disorders (NDDs) are studied. Yet, their utility for screening complex NDD etiologies and in drug discovery is limited by a lack of scalable and quantifiable derivation formats. Here, we describe the RosetteArray ® platform's ability to be used as an off-the-shelf, 96-well plate assay that standardizes incipient forebrain and spinal cord organoid morphogenesis as micropatterned, 3-D, singularly polarized neural rosette tissues (>9000 per plate). RosetteArrays are seeded from cryopreserved human pluripotent stem cells, cultured over 6-8 days, and immunostained images can be quantified using artificial intelligence-based software. We demonstrate the platform's suitability for screening developmental neurotoxicity and genetic and environmental factors known to cause neural tube defect risk. Given the presence of rosette morphogenesis perturbation in neural organoid models of NDDs and neurodegenerative disorders, the RosetteArray platform could enable quantitative high-throughput screening (qHTS) of human neurodevelopmental risk across regulatory and precision medicine applications.

Rigor and reproducibility in human brain organoid research: Where we are and where we need to go

Human brain organoid models have emerged as a promising tool for studying human brain development and function. These models preserve human genetics and recapitulate some aspects of human brain development, while facilitating manipulation in an in vitro setting. Despite their potential to transform biology and medicine, concerns persist about their fidelity. To fully harness their potential, it is imperative to establish reliable analytic methods, ensuring rigor and reproducibility. Here, we review current analytical platforms used to characterize human forebrain cortical organoids, highlight challenges, and propose recommendations for future studies to achieve greater precision and uniformity across laboratories.

Laminin-associated integrins mediate Diffuse Intrinsic Pontine Glioma infiltration and therapy response within a neural assembloid model

Diffuse Intrinsic Pontine Glioma (DIPG) is a highly aggressive and fatal pediatric brain cancer. One pre-requisite for tumor cells to infiltrate is adhesion to extracellular matrix (ECM) components. However, it remains largely unknown which ECM proteins are critical in enabling DIPG adhesion and migration and which integrin receptors mediate these processes. Here, we identify laminin as a key ECM protein that supports robust DIPG cell adhesion and migration. To study DIPG infiltration, we developed a DIPG-neural assembloid model, which is composed of a DIPG spheroid fused to a human induced pluripotent stem cell-derived neural organoid. Using this assembloid model, we demonstrate that knockdown of laminin-associated integrins significantly impedes DIPG infiltration. Moreover, laminin-associated integrin knockdown improves DIPG response to radiation and HDAC inhibitor treatment within the DIPG-neural assembloids. These findings reveal the critical role of laminin-associated integrins in mediating DIPG progression and drug response. The results also provide evidence that disrupting integrin receptors may offer a novel therapeutic strategy to enhance DIPG treatment outcomes. Finally, these results establish DIPG-neural assembloid models as a powerful tool to study DIPG disease progression and enable drug discovery.

The application of brain organoid for drug discovery in mitochondrial diseases

Mitochondrial diseases are difficult to treat due to the complexity and multifaceted nature of mitochondrial dysfunction. Brain organoids are three-dimensional (3D) structures derived from human pluripotent stem cells designed to mimic brain-like development and function. Brain organoids have received a lot of attention in recent years as powerful tools for modeling human diseases, brain development, and drug screening. Screening compounds for mitochondrial diseases using brain organoids could provide a more physiologically relevant platform for drug discovery. Brain organoids offer the possibility of personalized medicine because they can be derived from patient-specific cells, allowing testing of drugs tailored to specific genetic mutations. In this article, we highlight how brain organoids offer a promising avenue for screening compounds for mitochondrial diseases and address the challenges and limitations associated with their use. We hope this review will provide new insights into the further progress of brain organoids for mitochondrial screening studies.

In vitro human cell culture models in a bench-to-bedside approach to epilepsy

Epilepsy is the most common chronic neurological disease, affecting nearly 1%-2% of the world's population. Current pharmacological treatment and regimen adjustments are aimed at controlling seizures; however, they are ineffective in one-third of the patients. Although neuronal hyperexcitability was previously thought to be mainly due to ion channel alterations, current research has revealed other contributing molecular pathways, including processes involved in cellular signaling, energy metabolism, protein synthesis, axon guidance, inflammation, and others. Some forms of drug-resistant epilepsy are caused by genetic defects that constitute potential targets for precision therapy. Although such approaches are increasingly important, they are still in the early stages of development. This review aims to provide a summary of practical aspects of the employment of in vitro human cell culture models in epilepsy diagnosis, treatment, and research. First, we briefly summarize the genetic testing that may result in the detection of candidate pathogenic variants in genes involved in epilepsy pathogenesis. Consequently, we review existing in vitro cell models, including induced pluripotent stem cells and differentiated neuronal cells, providing their specific properties, validity, and employment in research pipelines. We cover two methodological approaches. The first approach involves the utilization of somatic cells directly obtained from individual patients, while the second approach entails the utilization of characterized cell lines. The models are evaluated in terms of their research and clinical benefits, relevance to the in vivo conditions, legal and ethical aspects, time and cost demands, and available published data. Despite the methodological, temporal, and financial demands of the reviewed models they possess high potential to be used as robust systems in routine testing of pathogenicity of detected variants in the near future and provide a solid experimental background for personalized therapy of genetic epilepsies. PLAIN LANGUAGE SUMMARY: Epilepsy affects millions worldwide, but current treatments fail for many patients. Beyond traditional ion channel alterations, various genetic factors contribute to the disorder's complexity. This review explores how in vitro human cell models, either from patients or from cell lines, can aid in understanding epilepsy's genetic roots and developing personalized therapies. While these models require further investigation, they offer hope for improved diagnosis and treatment of genetic forms of epilepsy.

Organoids Modeling Stroke in a Petri Dish

Stroke is a common neurological disorder, the second leading cause of death, and the third leading cause of disability. Unfortunately, the only approved drug for it is tissue plasminogen, but the therapeutic window is limited. In this context, preclinical studies are relevant to better dissect the underlying mechanisms of stroke and for the drug screening of potential therapies. Brain organoids could be relevant in this setting. They are derived from pluripotent stem cells or isolated organ progenitors that differentiate to form an organ-like tissue, exhibiting multiple cell types that self-organize to form a structure not unlike the organ in vivo. Brain organoids mimic many key features of early human brain development at molecular, cellular, structural, and functional levels and have emerged as novel model systems that can be used to investigate human brain diseases including stroke. Brain organoids are a promising and powerful tool for ischemic stroke studies; however, there are a few concerns that need to be addressed, including the lack of vascularization and the many cell types that are typically present in the human brain. The aim of this review is to discuss the potential of brain organoids as a novel model system for studying ischemic stroke, highlighting both the advantages and disadvantages in the use of this technology.

Organoids as preclinical models of human disease: progress and applications

In the field of biomedical research, organoids represent a remarkable advancement that has the potential to revolutionize our approach to studying human diseases even before clinical trials. Organoids are essentially miniature 3D models of specific organs or tissues, enabling scientists to investigate the causes of diseases, test new drugs, and explore personalized medicine within a controlled laboratory setting. Over the past decade, organoid technology has made substantial progress, allowing researchers to create highly detailed environments that closely mimic the human body. These organoids can be generated from various sources, including pluripotent stem cells, specialized tissue cells, and tumor tissue cells. This versatility enables scientists to replicate a wide range of diseases affecting different organ systems, effectively creating disease replicas in a laboratory dish. This exciting capability has provided us with unprecedented insights into the progression of diseases and how we can develop improved treatments. In this paper, we will provide an overview of the progress made in utilizing organoids as preclinical models, aiding our understanding and providing a more effective approach to addressing various human diseases.

Bibliometric analysis of global research on human organoids

The emergence and rapid development of human organoids have provided the possibility to replace animal models in treating human diseases. Intelligence studies help focus on research hotspots and address key mechanistic issues. Currently, few comprehensive studies describe the characteristics of human organoid research. In this study, we extracted 8,591 original articles on organoids from the Web of Science core collection database over the past two decades and conducted intelligence analysis using CiteSpace. The number of publications in this field has experienced rapid growth in the last ten years (almost 70-fold increase since 2009). The United States, China, Germany, Netherlands, and UK have strong collaborations in publishing articles. Clevers Hans, Van Der Laan, Jason R Spence, and Sato Toshiro have made significant contributions to advancing progress in this field. Clustering and burst analysis categorized research hotspots into tissue model and functional construction, intercellular signaling, immune mechanisms, and tumor metastasis. Organoid research in highly cited articles covers four major areas: basic research (38%), involving stem cell developmental processes and cell-cell interactions; biobanking (10%), with a focus on organoid cultivation; precision medicine (16%), emphasizing cell therapy and drug development; and disease modeling (36%), including pathogen analysis and screening for disease-related genetic variations. The main obstacles currently faced in organoid research include cost and technology, vascularization of cells, immune system establishment, international standard protocols, and limited availability of high-quality clinical trial data. Future research will focus on cost-saving measures, technology sharing, development of international standards, and conducting high-level clinical trials.

Brain Organoids: A Game-Changer for Drug Testing

Neurological disorders are the second cause of death and the leading cause of disability worldwide. Unfortunately, no cure exists for these disorders, but the actual therapies are only able to ameliorate people's quality of life. Thus, there is an urgent need to test potential therapeutic approaches. Brain organoids are a possible valuable tool in the study of the brain, due to their ability to reproduce different brain regions and maturation stages; they can be used also as a tool for disease modelling and target identification of neurological disorders. Recently, brain organoids have been used in drug-screening processes, even if there are several limitations to overcome. This review focuses on the description of brain organoid development and drug-screening processes, discussing the advantages, challenges, and limitations of the use of organoids in modeling neurological diseases. We also highlighted the potential of testing novel therapeutic approaches. Finally, we examine the challenges and future directions to improve the drug-screening process.

Dynamic culture of cerebral organoids using a pillar/perfusion plate for the assessment of developmental neurotoxicity

Despite the potential toxicity of commercial chemicals to the development of the nervous system (known as developmental neurotoxicity or DNT), conventional in vitro cell models have primarily been employed for the assessment of acute neuronal toxicity. On the other hand, animal models used for the assessment of DNT are not physiologically relevant due to the heterogenic difference between humans and animals. In addition, animal models are low-throughput, time-consuming, expensive, and ethically questionable. Recently, human brain organoids have emerged as a promising alternative to assess the detrimental effects of chemicals on the developing brain. However, conventional organoid culture systems have several technical limitations including low throughput, lack of reproducibility, insufficient maturity of organoids, and the formation of the necrotic core due to limited diffusion of nutrients and oxygen. To address these issues and establish predictive DNT models, cerebral organoids were differentiated in a dynamic condition in a unique pillar/perfusion plate, which were exposed to test compounds to evaluate DNT potential. The pillar/perfusion plate facilitated uniform, dynamic culture of cerebral organoids with improved proliferation and maturity by rapid, bidirectional flow generated on a digital rocker. Day 9 cerebral organoids in the pillar/perfusion plate were exposed to ascorbic acid (DNT negative) and methylmercury (DNT positive) in a dynamic condition for 1 and 3 weeks, and changes in organoid morphology and neural gene expression were measured to determine DNT potential. As expected, ascorbic acid didn't induce any changes in organoid morphology and neural gene expression. However, exposure of day 9 cerebral organoids to methylmercury resulted in significant changes in organoid morphology and neural gene expression. Interestingly, methylmercury did not induce adverse changes in cerebral organoids in a static condition, thus highlighting the importance of dynamic organoid culture in DNT assessment.

Neuropathogenesis-on-chips for neurodegenerative diseases

Developing diagnostics and treatments for neurodegenerative diseases (NDs) is challenging due to multifactorial pathogenesis that progresses gradually. Advanced in vitro systems that recapitulate patient-like pathophysiology are emerging as alternatives to conventional animal-based models. In this review, we explore the interconnected pathogenic features of different types of ND, discuss the general strategy to modelling NDs using a microfluidic chip, and introduce the organoid-on-a-chip as the next advanced relevant model. Lastly, we overview how these models are being applied in academic and industrial drug development. The integration of microfluidic chips, stem cells, and biotechnological devices promises to provide valuable insights for biomedical research and developing diagnostic and therapeutic solutions for NDs.

Synaptic plasticity in human thalamocortical assembloids

Synaptic plasticities, such as long-term potentiation (LTP) and depression (LTD), tune synaptic efficacy and are essential for learning and memory. Current studies of synaptic plasticity in humans are limited by a lack of adequate human models. Here, we modeled the thalamocortical system by fusing human induced pluripotent stem cell-derived thalamic and cortical organoids. Single-nucleus RNA-sequencing revealed that most cells in mature thalamic organoids were glutamatergic neurons. When fused to form thalamocortical assembloids, thalamic and cortical organoids formed reciprocal long-range axonal projections and reciprocal synapses detectable by light and electron microscopy, respectively. Using whole-cell patch-clamp electrophysiology and two-photon imaging, we characterized glutamatergic synaptic transmission. Thalamocortical and corticothalamic synapses displayed short-term plasticity analogous to that in animal models. LTP and LTD were reliably induced at both synapses; however, their mechanisms differed from those previously described in rodents. Thus, thalamocortical assembloids provide a model system for exploring synaptic plasticity in human circuits.

Alpha-synuclein pathology is associated with astrocyte senescence in a midbrain organoid model of familial Parkinson's disease

Parkinson's disease (PD) is a complex, progressive neurodegenerative disease characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta in the midbrain. Despite extensive research efforts, the molecular and cellular changes that precede neurodegeneration in PD are poorly understood. To address this, here we describe the use of patient specific human midbrain organoids harboring the SNCA triplication to investigate mechanisms underlying dopaminergic degeneration. Our midbrain organoid model recapitulates key pathological hallmarks of PD, including the aggregation of α-synuclein and the progressive loss of dopaminergic neurons. We found that these pathological hallmarks are associated with an increase in senescence associated cellular phenotypes in astrocytes including nuclear lamina defects, the presence of senescence associated heterochromatin foci, and the upregulation of cell cycle arrest genes. These results suggest a role of pathological α-synuclein in inducing astrosenescence which may, in turn, increase the vulnerability of dopaminergic neurons to degeneration.

Models for evaluating glioblastoma invasion along white matter tracts

White matter tracts (WMs) are one of the main invasion paths of glioblastoma multiforme (GBM). The lack of ideal research models hinders our understanding of the details and mechanisms of GBM invasion along WMs. To date, many potential in vitro models have been reported; nerve fiber culture models and nanomaterial models are biocompatible, and the former have electrically active neurons. Brain slice culture models, organoid models, and microfluidic chip models can simulate the real brain and tumor microenvironment (TME), which contains a variety of cell types. These models are closer to the real in vivo environment and are helpful for further studying not only invasion along WMs by GBM, but also perineural invasion and brain metastasis by solid tumors.

Exploiting spatiotemporal regulation of FZD5 during neural patterning for efficient ventral midbrain specification

The Wnt/β-catenin signaling governs anterior-posterior neural patterning during development. Current human pluripotent stem cell (hPSC) differentiation protocols use a GSK3 inhibitor to activate Wnt signaling to promote posterior neural fate specification. However, GSK3 is a pleiotropic kinase involved in multiple signaling pathways and, as GSK3 inhibition occurs downstream in the signaling cascade, it bypasses potential opportunities for achieving specificity or regulation at the receptor level. Additionally, the specific roles of individual FZD receptors in anterior-posterior patterning are poorly understood. Here, we have characterized the cell surface expression of FZD receptors in neural progenitor cells with different regional identity. Our data reveal unique upregulation of FZD5 expression in anterior neural progenitors, and this expression is downregulated as cells adopt a posterior fate. This spatial regulation of FZD expression constitutes a previously unreported regulatory mechanism that adjusts the levels of β-catenin signaling along the anterior-posterior axis and possibly contributes to midbrain-hindbrain boundary formation. Stimulation of Wnt/β-catenin signaling in hPSCs, using a tetravalent antibody that selectively triggers FZD5 and LRP6 clustering, leads to midbrain progenitor differentiation and gives rise to functional dopaminergic neurons in vitro and in vivo.

Recent approaches in regenerative medicine in the fight against neurodegenerative disease

Neurodegenerative diseases arise due to slow and gradual loss of structure and/or function of neurons and glial cells and cause different degrees of loss of cognition abilities and sensation. The little success in developing effective treatments imposes a high and regressive economic impact on society, patients and their families. In recent years, regenerative medicine has provided a great opportunity to research new innovative strategies with strong potential to treatleva these diseases. These effects are due to the ability of suitable cells and biomaterials to regenerate damaged nerves with differentiated cells, creating an appropriate environment for recovering or preserving existing healthy neurons and glial cells from destruction and damage. Ultimately, a better understanding and thus a further investigation of stem cell technology, tissue engineering, gene therapy, and exosomes allows progress towards practical and effective treatments for neurodegenerative diseases. Therefore, in this review, advances currently being developed in regenerative medicine using animal models and human clinical trials in neurological disorders are summarized.

Shaping the Neurovascular Unit Exploiting Human Brain Organoids

Brain organoids, three-dimensional cell structures derived from pluripotent stem cells, closely mimic key aspects of the human brain in vitro, providing a powerful tool for studying neurodevelopment and disease. The neuroectodermal induction protocol employed for brain organoid generation primarily gives rise to the neural cellular component but lacks the vital vascular system, which is crucial for the brain functions by regulating differentiation, migration, and circuit formation, as well as delivering oxygen and nutrients. Many neurological diseases are caused by dysfunctions of cerebral microcirculation, making vascularization of human brain organoids an important tool for pathogenetic and translational research. Experimentally, the creation of vascularized brain organoids has primarily focused on the fusion of vascular and brain organoids, on organoid transplantation in vivo, and on the use of microfluidic devices to replicate the intricate microenvironment of the human brain in vitro. This review summarizes these efforts and highlights the importance of studying the neurovascular unit in a forward-looking perspective of leveraging their use for understanding and treating neurological disorders.

Gliomas: a reflection of temporal gliogenic principles

The hijacking of early developmental programs is a canonical feature of gliomas where neoplastic cells resemble neurodevelopmental lineages and possess mechanisms of stem cell resilience. Given these parallels, uncovering how and when in developmental time gliomagenesis intersects with normal trajectories can greatly inform our understanding of tumor biology. Here, we review how elapsing time impacts the developmental principles of astrocyte (AS) and oligodendrocyte (OL) lineages, and how these same temporal programs are replicated, distorted, or circumvented in pathological settings such as gliomas. Additionally, we discuss how normal gliogenic processes can inform our understanding of the temporal progression of gliomagenesis, including when in developmental time gliomas originate, thrive, and can be pushed towards upon therapeutic coercion.

Brain organoids: A revolutionary tool for modeling neurological disorders and development of therapeutics

Brain organoids are self-organized, three-dimensional (3D) aggregates derived from pluripotent stem cells that have cell types and cellular architectures resembling those of the developing human brain. The current understanding of human brain developmental processes and neurological disorders has advanced significantly with the introduction of this in vitro model. Brain organoids serve as a translational link between two-dimensional (2D) cultures and in vivo models which imitate the neural tube formation at the early and late stages and the differentiation of neuroepithelium with whole-brain regionalization. In addition, the generation of region-specific brain organoids made it possible to investigate the pathogenic and etiological aspects of acquired and inherited brain disease along with drug discovery and drug toxicity testing. In this review article, we first summarize an overview of the existing methods and platforms used for generating brain organoids and their limitations and then discuss the recent advancement in brain organoid technology. In addition, we discuss how brain organoids have been used to model aspects of neurodevelopmental and neurodegenerative diseases, including autism spectrum disorder (ASD), Rett syndrome, Zika virus-related microcephaly, Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD).

Can pluripotent/multipotent stem cells reverse Parkinson's disease progression?

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by continuous and selective degeneration or death of dopamine neurons in the midbrain, leading to dysfunction of the nigrostriatal neural circuits. Current clinical treatments for PD include drug treatment and surgery, which provide short-term relief of symptoms but are associated with many side effects and cannot reverse the progression of PD. Pluripotent/multipotent stem cells possess a self-renewal capacity and the potential to differentiate into dopaminergic neurons. Transplantation of pluripotent/multipotent stem cells or dopaminergic neurons derived from these cells is a promising strategy for the complete repair of damaged neural circuits in PD. This article reviews and summarizes the current preclinical/clinical treatments for PD, their efficacies, and the advantages/disadvantages of various stem cells, including pluripotent and multipotent stem cells, to provide a detailed overview of how these cells can be applied in the treatment of PD, as well as the challenges and bottlenecks that need to be overcome in future translational studies.

A cell therapy approach based on iPSC-derived midbrain organoids for the restoration of motor function in a Parkinson's disease mouse model

Parkinson's disease (PD) is a neurodegenerative disease characterized by the degeneration of dopaminergic (DA) neurons in the substantia nigra and loss of DA transmission in the striatum, thus making cell transplantation an effective treatment strategy. Here, we develop a cellular therapy based on induced pluripotent stem cell (iPSC)-derived midbrain organoids. By transplanting midbrain organoid cells into the striatum region of a 6-OHDA-lesioned PD mouse model, we found that the transplanted cells survived and highly efficiently differentiated into DA neurons. Further, using a dopamine sensor, we observed that the differentiated human DA neurons could efficiently release dopamine and were integrated into the neural network of the PD mice. Moreover, starting from four weeks after transplantation, the motor function of the transplanted mice could be significantly improved. Therefore, cell therapy based on iPSC-derived midbrain organoids can be a potential strategy for the clinical treatment of PD.

Patterning ganglionic eminences in developing human brain organoids using a morphogen-gradient-inducing device

In early neurodevelopment, the central nervous system is established through the coordination of various neural organizers directing tissue patterning and cell differentiation. Better recapitulation of morphogen gradient production and signaling will be crucial for establishing improved developmental models of the brain in vitro. Here, we developed a method by assembling polydimethylsiloxane devices capable of generating a sustained chemical gradient to produce patterned brain organoids, which we termed morphogen-gradient-induced brain organoids (MIBOs). At 3.5 weeks, MIBOs replicated dorsal-ventral patterning observed in the ganglionic eminences (GE). Analysis of mature MIBOs through single-cell RNA sequencing revealed distinct dorsal GE-derived CALB2+ interneurons, medium spiny neurons, and medial GE-derived cell types. Finally, we demonstrate long-term culturing capabilities with MIBOs maintaining stable neural activity in cultures grown up to 5.5 months. MIBOs demonstrate a versatile approach for generating spatially patterned brain organoids for embryonic development and disease modeling.

Uniform cerebral organoid culture on a pillar plate by simple and reproducible spheroid transfer from an ultralow attachment well plate

Human induced pluripotent stem cell (iPSC)-derived brain organoids have potential to recapitulate the earliest stages of brain development, serving as an effectivein vitromodel for studying both normal brain development and disorders. However, current brain organoid culture methods face several challenges, including low throughput, high variability in organoid generation, and time-consuming, multiple transfer and encapsulation of cells in hydrogels throughout the culture. These limitations hinder the widespread application of brain organoids including high-throughput assessment of compounds in clinical and industrial lab settings. In this study, we demonstrate a straightforward approach of generating multiple cerebral organoids from iPSCs on a pillar plate platform, eliminating the need for labor-intensive, multiple transfer and encapsulation steps to ensure the reproducible generation of cerebral organoids. We formed embryoid bodies in an ultra-low attachment 384-well plate and subsequently transferred them to the pillar plate containing Matrigel, using a straightforward sandwiching and inverting method. Each pillar on the pillar plate contains a single spheroid, and the success rate of spheroid transfer was in a range of 95%-100%. Using this approach, we robustly generated cerebral organoids on the pillar plate and demonstrated an intra-batch coefficient of variation below 9%-19% based on ATP-based cell viability and compound treatment. Notably, our spheroid transfer method in combination with the pillar plate allows miniaturized culture of cerebral organoids, alleviates the issue of organoid variability, and has potential to significantly enhance assay throughput by allowingin situorganoid assessment as compared to conventional organoid culture in 6-/24-well plates, petri dishes, and spinner flasks.

Graphene Oxide Nanoparticles and Organoids: A Prospective Advanced Model for Pancreatic Cancer Research

Pancreatic cancer, notorious for its grim 10% five-year survival rate, poses significant clinical challenges, largely due to late-stage diagnosis and limited therapeutic options. This review delves into the generation of organoids, including those derived from resected tissues, biopsies, pluripotent stem cells, and adult stem cells, as well as the advancements in 3D printing. It explores the complexities of the tumor microenvironment, emphasizing culture media, the integration of non-neoplastic cells, and angiogenesis. Additionally, the review examines the multifaceted properties of graphene oxide (GO), such as its mechanical, thermal, electrical, chemical, and optical attributes, and their implications in cancer diagnostics and therapeutics. GO's unique properties facilitate its interaction with tumors, allowing targeted drug delivery and enhanced imaging for early detection and treatment. The integration of GO with 3D cultured organoid systems, particularly in pancreatic cancer research, is critically analyzed, highlighting current limitations and future potential. This innovative approach has the promise to transform personalized medicine, improve drug screening efficiency, and aid biomarker discovery in this aggressive disease. Through this review, we offer a balanced perspective on the advancements and future prospects in pancreatic cancer research, harnessing the potential of organoids and GO.

Disruption of lysosomal proteolysis in astrocytes facilitates midbrain organoid proteostasis failure in an early-onset Parkinson's disease model

Accumulation of advanced glycation end products (AGEs) on biopolymers accompanies cellular aging and drives poorly understood disease processes. Here, we studied how AGEs contribute to development of early onset Parkinson's Disease (PD) caused by loss-of-function of DJ1, a protein deglycase. In induced pluripotent stem cell (iPSC)-derived midbrain organoid models deficient for DJ1 activity, we find that lysosomal proteolysis is impaired, causing AGEs to accumulate, α-synuclein (α-syn) phosphorylation to increase, and proteins to aggregate. We demonstrated these processes are at least partly driven by astrocytes, as DJ1 loss reduces their capacity to provide metabolic support and triggers acquisition of a pro-inflammatory phenotype. Consistently, in co-cultures, we find that DJ1-expressing astrocytes are able to reverse the proteolysis deficits of DJ1 knockout midbrain neurons. In conclusion, astrocytes' capacity to clear toxic damaged proteins is critical to preserve neuronal function and their dysfunction contributes to the neurodegeneration observed in a DJ1 loss-of-function PD model.

Human cerebellar organoids with functional Purkinje cells

Research on human cerebellar development and disease has been hampered by the need for a human cell-based system that recapitulates the human cerebellum's cellular diversity and functional features. Here, we report a human organoid model (human cerebellar organoids [hCerOs]) capable of developing the complex cellular diversity of the fetal cerebellum, including a human-specific rhombic lip progenitor population that have never been generated in vitro prior to this study. 2-month-old hCerOs form distinct cytoarchitectural features, including laminar organized layering, and create functional connections between inhibitory and excitatory neurons that display coordinated network activity. Long-term culture of hCerOs allows healthy survival and maturation of Purkinje cells that display molecular and electrophysiological hallmarks of their in vivo counterparts, addressing a long-standing challenge in the field. This study therefore provides a physiologically relevant, all-human model system to elucidate the cell-type-specific mechanisms governing cerebellar development and disease.

Towards improved screening of toxins for Parkinson's risk

Parkinson's disease (PD) is a chronic, progressive and disabling neurodegenerative disorder. The prevalence of PD has risen considerably over the past decades. A growing body of evidence suggest that exposure to environmental toxins, including pesticides, solvents and heavy metals (collectively called toxins), is at least in part responsible for this rapid growth. It is worrying that the current screening procedures being applied internationally to test for possible neurotoxicity of specific compounds offer inadequate insights into the risk of developing PD in humans. Improved screening procedures are therefore urgently needed. Our review first substantiates current evidence on the relation between exposure to environmental toxins and the risk of developing PD. We subsequently propose to replace the current standard toxin screening by a well-controlled multi-tier toxin screening involving the following steps: in silico studies (tier 1) followed by in vitro tests (tier 2), aiming to prioritize agents with human relevant routes of exposure. More in depth studies can be undertaken in tier 3, with whole-organism (in)vertebrate models. Tier 4 has a dedicated focus on cell loss in the substantia nigra and on the presumed mechanisms of neurotoxicity in rodent models, which are required to confirm or refute the possible neurotoxicity of any individual compound. This improved screening procedure should not only evaluate new pesticides that seek access to the market, but also critically assess all pesticides that are being used today, acknowledging that none of these has ever been proven to be safe from a perspective of PD. Importantly, the improved screening procedures should not just assess the neurotoxic risk of isolated compounds, but should also specifically look at the cumulative risk conveyed by exposure to commonly used combinations of pesticides (cocktails). The worldwide implementation of such an improved screening procedure, would be an essential step for policy makers and governments to recognize PD-related environmental risk factors.

Diencephalic organoids - A key to unraveling development, connectivity, and pathology of the human diencephalon

The diencephalon, an integral component of the forebrain, governs a spectrum of crucial functions, ranging from sensory processing to emotional regulation. Yet, unraveling its unique development, intricate connectivity, and its role in neurodevelopmental disorders has long been hampered by the scarcity of human brain tissue and ethical constraints. Recent advancements in stem cell technology, particularly the emergence of brain organoids, have heralded a new era in neuroscience research. Although most brain organoid methodologies have hitherto concentrated on directing stem cells toward telencephalic fates, novel techniques now permit the generation of region-specific brain organoids that faithfully replicate precise diencephalic identities. These models mirror the complexity of the human diencephalon, providing unprecedented opportunities for investigating diencephalic development, functionality, connectivity, and pathophysiology in vitro. This review summarizes the development, function, and connectivity of diencephalic structures and touches upon developmental brain disorders linked to diencephalic abnormalities. Furthermore, it presents current diencephalic organoid models and their applications in unraveling the intricacies of diencephalic development, function, and pathology in humans. Lastly, it highlights thalamocortical assembloid models, adept at capturing human-specific aspects of thalamocortical connections, along with their relevance in neurodevelopmental disorders.

An AI-based segmentation and analysis pipeline for high-field MR monitoring of cerebral organoids

Cerebral organoids recapitulate the structure and function of the developing human brain in vitro, offering a large potential for personalized therapeutic strategies. The enormous growth of this research area over the past decade with its capability for clinical translation makes a non-invasive, automated analysis pipeline of organoids highly desirable. This work presents a novel non-invasive approach to monitor and analyze cerebral organoids over time using high-field magnetic resonance imaging and state-of-the-art tools for automated image analysis. Three specific objectives are addressed, (I) organoid segmentation to investigate organoid development over time, (II) global cysticity classification and (III) local cyst segmentation for organoid quality assessment. We show that organoid growth can be monitored reliably over time and cystic and non-cystic organoids can be separated with high accuracy, with on par or better performance compared to state-of-the-art tools applied to brightfield imaging. Local cyst segmentation is feasible but could be further improved in the future. Overall, these results highlight the potential of the pipeline for clinical application to larger-scale comparative organoid analysis.

Microfluidic Brain-on-a-Chip: From Key Technology to System Integration and Application

As an ideal in vitro model, brain-on-chip (BoC) is an important tool to comprehensively elucidate brain characteristics. However, the in vitro model for the definition scope of BoC has not been universally recognized. In this review, BoC is divided into brain cells-on-a- chip, brain slices-on-a-chip, and brain organoids-on-a-chip according to the type of culture on the chip. Although these three microfluidic BoCs are constructed in different ways, they all use microfluidic chips as carrier tools. This method can better meet the needs of maintaining high culture activity on a chip for a long time. Moreover, BoC has successfully integrated cell biology, the biological material platform technology of microenvironment on a chip, manufacturing technology, online detection technology on a chip, and so on, enabling the chip to present structural diversity and high compatibility to meet different experimental needs and expand the scope of applications. Here, the relevant core technologies, challenges, and future development trends of BoC are summarized.

Efficient generation of brain organoids using magnetized gold nanoparticles

Brain organoids, which are three-dimensional cell culture models, have the ability to mimic certain structural and functional aspects of the human brain. However, creating these organoids can be a complicated and difficult process due to various technological hurdles. This study presents a method for effectively generating cerebral organoids from human induced pluripotent stem cells (hiPSCs) using electromagnetic gold nanoparticles (AuNPs). By exposing mature cerebral organoids to magnetized AuNPs, we were able to cultivate them in less than 3 weeks. The initial differentiation and neural induction of the neurosphere occurred within the first week, followed by maturation, including regional patterning and the formation of complex networks, during the subsequent 2 weeks under the influence of magnetized AuNPs. Furthermore, we observed a significant enhancement in neurogenic maturation in the brain organoids, as evidenced by increased histone acetylation in the presence of electromagnetic AuNPs. Consequently, electromagnetic AuNPs offer a promising in vitro system for efficiently generating more advanced human brain organoids that closely resemble the complexity of the human brain.

In vitro modeling of the human dopaminergic system using spatially arranged ventral midbrain-striatum-cortex assembloids

Ventral midbrain dopaminergic neurons project to the striatum as well as the cortex and are involved in movement control and reward-related cognition. In Parkinson's disease, nigrostriatal midbrain dopaminergic neurons degenerate and cause typical Parkinson's disease motor-related impairments, while the dysfunction of mesocorticolimbic midbrain dopaminergic neurons is implicated in addiction and neuropsychiatric disorders. Study of the development and selective neurodegeneration of the human dopaminergic system, however, has been limited due to the lack of an appropriate model and access to human material. Here, we have developed a human in vitro model that recapitulates key aspects of dopaminergic innervation of the striatum and cortex. These spatially arranged ventral midbrain-striatum-cortical organoids (MISCOs) can be used to study dopaminergic neuron maturation, innervation and function with implications for cell therapy and addiction research. We detail protocols for growing ventral midbrain, striatal and cortical organoids and describe how they fuse in a linear manner when placed in custom embedding molds. We report the formation of functional long-range dopaminergic connections to striatal and cortical tissues in MISCOs, and show that injected, ventral midbrain-patterned progenitors can mature and innervate the tissue. Using these assembloids, we examine dopaminergic circuit perturbations and show that chronic cocaine treatment causes long-lasting morphological, functional and transcriptional changes that persist upon drug withdrawal. Thus, our method opens new avenues to investigate human dopaminergic cell transplantation and circuitry reconstruction as well as the effect of drugs on the human dopaminergic system.

Bibliometric analysis of cerebral organoids and diseases in the last 10 years

Cerebral organoids have emerged as a powerful tool for mirroring the brain developmental processes and replicating its unique physiology. This bibliometric analysis aims to delineate the burgeoning trends in the application of cerebral organoids in disease research and offer insights for future investigations. We screened all relevant literature from the Web of Science on cerebral organoids in disease research during the period 2013-2022 and analyzed the research trends in the field using VOSviewer, CiteSpace, and Scimago Graphica software. According to the search strategy, 592 articles were screened out. The United States of America (USA) was the most productive, followed by China and Germany. The top nine institutions in terms of the number of publications include Canada and the United States, with the University of California, San Diego (USA), having the highest number of publications. The International Journal of Molecular Sciences was the most productive journal. Knoblich, Juergen A., and Lancaster, Madeline A. published the highest number of articles. Keyword cluster analysis showed that current research trends focused more on induced pluripotent stem cells to construct organoid models of cerebral diseases and the exploration of their mechanisms and therapeutic modalities. This study provides a comprehensive summary and analysis of global research trends in the field of cerebral organoids in diseases. In the past decade, the number of high-quality papers in this field has increased significantly, and cerebral organoids provide hope for simulating nervous system diseases (such as Alzheimer's disease).

Cell Replacement Therapy for Brain Repair: Recent Progress and Remaining Challenges for Treating Parkinson's Disease and Cortical Injury

Neural transplantation represents a promising approach to repairing damaged brain circuitry. Cellular grafts have been shown to promote functional recovery through "bystander effects" and other indirect mechanisms. However, extensive brain lesions may require direct neuronal replacement to achieve meaningful restoration of function. While fetal cortical grafts have been shown to integrate with the host brain and appear to develop appropriate functional attributes, the significant ethical concerns and limited availability of this tissue severely hamper clinical translation. Induced pluripotent stem cell-derived cells and tissues represent a more readily scalable alternative. Significant progress has recently been made in developing protocols for generating a wide range of neural cell types in vitro. Here, we discuss recent progress in neural transplantation approaches for two conditions with distinct design needs: Parkinson's disease and cortical injury. We discuss the current status and future application of injections of dopaminergic cells for the treatment of Parkinson's disease as well as the use of structured grafts such as brain organoids for cortical repair.

Modeling early human cortical development and evaluating neurotoxicity with a forebrain organoid system

The complexity and subtlety of brain development renders it challenging to examine effects of environmental toxicants on human fetal brain development. Advances in pluripotent cell-derived organoid systems open up novel avenues for human development, disease and toxicity modeling. Here, we have established a forebrain organoid system and recapitulated early human cortical development spatiotemporally including neuroepithelium induction, apical-basal axis formation, neural progenitor proliferation and maintenance, neuronal differentiation and layer/region patterning. To explore whether this forebrain organoid system is suitable for neurotoxicity modeling, we subjected the organoids to bisphenol A (BPA), a common environmental toxicant of global presence and high epidemic significance. BPA exposure caused substantial abnormalities in key cortical developmental events, inhibited progenitor cell proliferation and promoted precocious neuronal differentiation, leading premature progenitor cell depletion and aberrant cortical layer patterning and structural organization. Consistent with an antagonistic mechanism between thyroid hormone and BPA, T3 supplementation attenuated BPA-mediated cortical developmental abnormalities. Altogether, our in vitro recapitulation of cortical development with forebrain organoids provides a paradigm for efficient neural development and toxicity modeling and related remedy testing/screening.

Alveolar Type 2 Epithelial Cell Organoids: Focus on Culture Methods

Lung diseases rank third in terms of mortality and represent a significant economic burden globally. Scientists have been conducting research to better understand respiratory diseases and find treatments for them. An ideal in vitro model must mimic the in vivo organ structure, physiology, and pathology. Organoids are self-organizing, three-dimensional (3D) structures originating from adult stem cells, embryonic lung bud progenitors, embryonic stem cells (ESCs), and induced pluripotent stem cells (iPSCs). These 3D organoid cultures may provide a platform for exploring tissue development, the regulatory mechanisms related to the repair of lung epithelia, pathophysiological and immunomodulatory responses to different respiratory conditions, and screening compounds for new drugs. To create 3D lung organoids in vitro, both co-culture and feeder-free methods have been used. However, there exists substantial heterogeneity in the organoid culture methods, including the sources of AT2 cells, media composition, and feeder cell origins. This article highlights the currently available methods for growing AT2 organoids and prospective improvements to improve the available culture techniques/conditions. Further, we discuss various applications, particularly those aimed at modeling human distal lung diseases and cell therapy.

Parkinson's disease: an update on preclinical studies of induced pluripotent stem cells

Parkinson's disease (PD) is the second most prevalent neurodegenerative disease among adults worldwide. It is characterised by the death of dopaminergic neurons in the substantia nigra pars compacta and, in some cases, presence of intracytoplasmic inclusions of α-synuclein, called Lewy bodies, a pathognomonic sign of the disease. Clinical diagnosis of PD is based on the presence of motor alterations. The treatments currently available have no neuroprotective effect. The exact causes of PD are poorly understood. Therefore, more precise preclinical models have been developed in recent years that use induced pluripotent stem cells (iPSC). In vitro studies can provide new information on PD pathogenesis and may help to identify new therapeutic targets or to develop new drugs.

Uniform cerebral organoid culture on a pillar plate by simple and reproducible spheroid transfer from an ultralow attachment well plate

Human induced pluripotent stem cell (iPSCs)-derived brain organoids have potential to recapitulate the earliest stages of brain development, serving as an effective in vitro model for studying both normal brain development and disorders. However, current brain organoid culture methods face several challenges, including low throughput, high variability in organoid generation, and time-consuming, multiple transfer and encapsulation of cells in hydrogels throughout the culture. These limitations hinder the widespread application of brain organoids including high-throughput assessment of compounds in clinical and industrial lab settings. In this study, we demonstrate a straightforward approach of generating multiple cerebral organoids from iPSCs on a pillar plate platform, eliminating the need for labor-intensive, multiple transfer and encapsulation steps to ensure the reproducible generation of cerebral organoids. We formed embryoid bodies (EBs) in an ultra-low attachment (ULA) 384-well plate and subsequently transferred them to the pillar plate containing Matrigel, using a straightforward sandwiching and inverting method. Each pillar on the pillar plate contains a single spheroid, and the success rate of spheroid transfer was in a range of 95 - 100%. By differentiating the EBs on the pillar plate, we achieved robust generation of cerebral organoids with a coefficient of variation (CV) below 19%. Notably, our spheroid transfer method in combination with the pillar plate allows miniaturized culture of cerebral organoids, alleviates the issue of organoid variability, and has potential to significantly enhance assay throughput by allowing in situ organoid assessment as compared to conventional organoid culture in 6-/24-well plates, petri dishes, and spinner flasks.

In depth characterization of midbrain organoids derived from wild type iPSC lines

The ability to model human neurological tissues in vitro has been a major hurdle to effective drug development for neurological disorders. iPSC-derived brain organoids have emerged as a compelling solution to this problem as they have the potential to relevantly model the protein expression pattern and physiology of specific brain regions. Although many protocols now exist for the production of brain organoids, few attempts have been made to do an in-depth kinetic evaluation of expression of mature regiospecific markers of brain organoids. To address this, we differentiated midbrain-specific brain organoids from iPSC-lines derived from three apparently healthy individuals using a matrix-free, bioreactor method. We monitored the expression of midbrain-specific neuronal markers from 7 to 90-days using immunofluorescence and immunohistology. The organoids were further characterized using electron microscopy and RNA-seq. In addition to serving as a potential benchmark for the future evaluation of other differentiation protocols, the markers observed in this study can be useful as control parameters to identify and evaluate the disease phenotypes in midbrain organoid derived from patient iPSC-lines with genetic neurological disorders.

The NLRP3 Inflammasome in Neurodegenerative Disorders: Insights from Epileptic Models

Neuroinflammation represents a dynamic process of defense and protection against the harmful action of infectious agents or other detrimental stimuli in the central nervous system (CNS). However, the uncontrolled regulation of this physiological process is strongly associated with serious dysfunctional neuronal issues linked to the progression of CNS disorders. Moreover, it has been widely demonstrated that neuroinflammation is linked to epilepsy, one of the most prevalent and serious brain disorders worldwide. Indeed, NLRP3, one of the most well-studied inflammasomes, is involved in the generation of epileptic seizures, events that characterize this pathological condition. In this context, several pieces of evidence have shown that the NLRP3 inflammasome plays a central role in the pathophysiology of mesial temporal lobe epilepsy (mTLE). Based on an extensive review of the literature on the role of NLRP3-dependent inflammation in epilepsy, in this review we discuss our current understanding of the connection between NLRP3 inflammasome activation and progressive neurodegeneration in epilepsy. The goal of the review is to cover as many of the various known epilepsy models as possible, providing a broad overview of the current literature. Lastly, we also propose some of the present therapeutic strategies targeting NLRP3, aiming to provide potential insights for future studies.

Volumetric compression by heterogeneous scaffold embedding promotes cerebral organoid maturation and does not impede growth

Although biochemical regulation has been extensively studied in organoid modeling protocols, the role of mechanoregulation in directing stem cell fate and organoid development has been relatively unexplored. To accurately replicate the dynamic organoid development observed in nature, in this study, we present a method of heterogeneous embedding using an alginate-shell-Matrigel-core system. This approach allows for cell-Matrigel remodeling by the inner layer and provides short-term moderate-normal compression through the soft alginate outer layer. Our results show that the time-limited confinement contributes to increased expression of neuronal markers such as neurofilament (NF) and microtubule-associated protein 2 (MAP2). Compared with non-alginate embedding and alginate compression groups, volume growth remains unimpeded. Our findings demonstrate the temporary mechanical regulation of cerebral organoid growth, which exhibits a regular growth profile with enhanced maturation. These results highlight the importance and potential practical applications of mechanoregulation in the establishment of brain organoids. A record of this paper's transparent peer review process is included in the supplemental information.

Single-cell transcriptomics identifies perturbed molecular pathways in midbrain organoids using α-synuclein triplication Parkinson's disease patient-derived iPSCs

Three-dimensional (3D) brain organoids provide a platform to study brain development, cellular coordination, and disease using human tissue. Here, we generate midbrain dopaminergic (mDA) organoids from induced pluripotent stem cells (iPSC) from healthy and Parkinson's Disease (PD) donors and assess them as a human PD model using single-cell RNAseq. We characterize cell types in our organoid cultures and analyze our model's Dopamine (DA) neurons using cytotoxic and genetic stressors. Our study provides the first in-depth, single-cell analysis of SNCA triplication and shows evidence for molecular dysfunction in oxidative phosphorylation, translation, and ER protein-folding in DA neurons. We perform an in-silico identification of rotenone-sensitive DA neurons and characterization of corresponding transcriptomic profiles associated with synaptic signalling and cholesterol biosynthesis. Finally, we show a novel chimera organoid model from healthy and PD iPSCs allowing the study of DA neurons from different individuals within the same tissue.

Production of Highly Uniform Midbrain Organoids from Human Pluripotent Stem Cells

Brain organoids have been considered as an advanced platform for in vitro disease modeling and drug screening, but numerous roadblocks exist, such as lack of large-scale production technology and lengthy protocols with multiple manipulation steps, impeding the industrial translation of brain organoid technology. Here, we describe the high-speed and large-scale production of midbrain organoids using a high-throughput screening-compatible platform within 30 days. Micro midbrain organoids (µMOs) exhibit a highly uniform morphology and gene expression pattern with minimal variability. Notably, µMOs show dramatically accelerated maturation, resulting in the generation of functional µMOs within only 30 days of differentiation. Furthermore, individual µMOs display highly consistent responsiveness to neurotoxin, suggesting their usefulness as an in vitro high-throughput drug toxicity screening platform. Collectively, our data indicate that µMO technology could represent an advanced and robust platform for in vitro disease modeling and drug screening for human neuronal diseases.

The dopamine hypothesis of autism spectrum disorder: A comprehensive analysis of the evidence

Despite intensive research into the etiopathogenesis of autism spectrum disorder (ASD), limited progress has been achieved so far. Among the plethora of models seeking to clarify how ASD arises, a coherent dopaminergic model was lacking until recently. In 2017, we provided a theoretical framework that we designated "the dopamine hypothesis of ASD". In the meantime, numerous studies yielded empirical evidence for this model. 4 years later, we provided a second version encompassing a refined and reconceptualized framework that accounted for these novel findings. In this chapter, we will review the evidence backing the previous versions of our model and add the most recent developments to the picture. Along these lines, we intend to lay out a comprehensive analysis of the supporting evidence for the dopamine hypothesis of ASD.