Браузер не даёт сохранять данные (например, приватный режим): закладки пропадут после закрытия вкладки.
Поиск статей PubMed
Ключевые слова, автор, журнал, годы — результаты из PubMed, аннотации с переводом на русский, закладки в браузере.
Найдено: 5 450
Страница 72 из 545-
Benchmarking brain organoid recapitulation of fetal corticogenesis.
Brain organoids are becoming increasingly relevant to dissect the molecular mechanisms underlying psychiatric and neurological conditions. The in vitro recapitulation of key features of human brain development affords the unique opportunity of investigating the developmental antecedents of neuropsychiatric conditions in the context of the actual patients' genetic backgrounds. Specifically, multiple strategies of brain organoid (BO) differentiation have enabled the investigation of human cerebral corticogenesis in vitro with increasing accuracy. However, the field lacks a systematic investigation of how closely the gene co-expression patterns seen in cultured BO from different protocols match those observed in fetal cortex, a paramount information for ensuring the sensitivity and accuracy of modeling disease trajectories. Here we benchmark BO against fetal corticogenesis by integrating transcriptomes from in-house differentiated cortical BO (CBO), other BO systems, human fetal brain samples processed in-house, and prenatal cortices from the BrainSpan Atlas. We identified co-expression patterns and prioritized hubs of human corticogenesis and CBO differentiation, highlighting both well-preserved and discordant trends across BO protocols. We evaluated the relevance of identified gene modules for neurodevelopmental disorders and psychiatric conditions finding significant enrichment of disease risk genes especially in modules related to neuronal maturation and synapsis development. The longitudinal transcriptomic analysis of CBO revealed a two-step differentiation composed of a fast-evolving phase, corresponding to the appearance of the main cell populations of the cortex, followed by a slow-evolving one characterized by milder transcriptional changes. Finally, we observed heterochronicity of differentiation across BO models compared to fetal cortex. Our approach provides a framework to directly compare the extent of in vivo/in vitro alignment of neurodevelopmentally relevant processes and their attending temporalities, structured as a resource to query for modeling human corticogenesis and the neuropsychiatric outcomes of its alterations.
-
Brain organoids, consciousness, ethics and moral status.
Advances in the field of human stem cells are often a source of public and ethical controversy. Researchers must frequently balance diverse societal perspectives on questions of morality with the pursuit of medical therapeutics and innovation. Recent developments in brain organoids make this challenge even more acute. Brain organoids are a new class of brain surrogate generated from human pluripotent stem cells (hPSCs). They have gained traction as a model for studying the intricacies of the human brain by using advancements in stem cell biology to recapitulate aspects of the developing human brain in vitro. However, recent observation of neural oscillations spontaneously emerging from these organoids raises the question of whether brain organoids are or could become conscious. At the same time, brain organoids offer a potentially unique opportunity to scientifically understand consciousness. To address these issues, experimental biologists, philosophers, and ethicists united to discuss the possibility of consciousness in human brain organoids and the consequent ethical and moral implications.
-
A robust protocol for the generation of human midbrain organoids.
The lack of advanced in vitro models recapitulating the human brain complexity is still a major obstacle in brain development and neurological disease research. Here, we describe a robust protocol to derive human midbrain organoids from neuroepithelial stem cells. These complex 3D models are characterized by the presence of functional neurons, including dopaminergic neurons and glial cells, making them particularly attractive for the study of Parkinson disease. For complete details on the use and execution of this protocol, please refer to Monzel et al. (2017).
-
Generation of Individualized, Standardized, and Electrically Synchronized Human Midbrain Organoids.
Organoids allow to model healthy and diseased human tissues. and have applications in developmental biology, drug discovery, and cell therapy. Traditionally cultured in immersion/suspension, organoids face issues like lack of standardization, fusion, hypoxia-induced necrosis, continuous agitation, and high media volume requirements. To address these issues, we developed an air-liquid interface (ALi) technology for culturing organoids, termed AirLiwell. It uses non-adhesive microwells for generating and maintaining individualized organoids on an air-liquid interface. This method ensures high standardization, prevents organoid fusion, eliminates the need for agitation, simplifies media changes, reduces media volume, and is compatible with Good Manufacturing Practices. We compared the ALi method to standard immersion culture for midbrain organoids, detailing the process from human pluripotent stem cell (hPSC) culture to organoid maturation and analysis. Air-liquid interface organoids (3D-ALi) showed optimized size and shape standardization. RNA sequencing and immunostaining confirmed neural/dopaminergic specification. Single-cell RNA sequencing revealed that immersion organoids (3D-i) contained 16% fibroblast-like, 23% myeloid-like, and 61% neural cells (49% neurons), whereas 3D-ALi organoids comprised 99% neural cells (86% neurons). Functionally, 3D-ALi organoids showed a striking electrophysiological synchronization, unlike the heterogeneous activity of 3D-i organoids. This standardized organoid platform improves reproducibility and scalability, demonstrated here with midbrain organoids. The use of midbrain organoids is particularly relevant for neuroscience and neurodegenerative diseases, such as Parkinson's disease, due to their high incidence, opening new perspectives in disease modeling and cell therapy. In addition to hPSC-derived organoids, the method's versatility extends to cancer organoids and 3D cultures from primary human cells.
-
Synergistic stress-relieving and cognitive-enhancing effects of walnut peptide and theanine in human brain organoid and mouse stress models.
BACKGROUND: Stress is a prevalent mental health concern that often emerges in late adolescence or early adulthood. Since 2007, the Food and Drug Administration (FDA) has not approved any novel anxiolytic pharmaceuticals, leading to increased interest in nutritional supplements as alternative therapies for stress management. PURPOSE: Building on our previous study, this work aims to investigate the synergistic effects of Theanine (Th) and Walnut Peptide (WP) on stress mitigation and cognitive enhancement. STUDY DESIGN: This study employed both in vitro and in vivo approaches. The former employed the human brain organoid stress (BO-stress) model, while the latter utilized the C57BL/6J mouse-stress model to evaluate the effect of Th and WP. METHODS: In the BO-stress model, the Th and WP combination was assessed for its effects on stress levels and the expression of neurotransmitters (GABA: Gamma-Aminobutyric Acid; 5-HT: serotonin; DA: dopamine; Ach: acetylcholine), as well as brain-derived neurotrophic factor (BDNF) and serotonin transporter (SERT). In the in vivo study, mice were administered Th (85 mg/ml) + WP (200 mg/ml) or with vehicles (e.g., powder, yogurt, milk), and assessed for stress and cognitive performance. Neurotransmitter levels, SERT and BDNF expression levels were also measured. RESULTS: The BO-stress model demonstrated that Th + WP reduced stress and regulated the expression of neurotransmitters and neurotrophic factors. In the mouse-stress model, the treatment improved stress and cognitive performance, partially normalizing neurotransmitter imbalances by modulating SERT and BDNF expression. We also revealed a correlation between SERT levels in the BO-stress model and those in the hippocampus of the mouse-stress model (r = 0.640). Western blot analysis further demonstrated Th + WP upregulated the expression of BDNF, TrkB (Tyrosine kinase B) and phosphorylation of CREB (cAMP response element-binding protein). CONCLUSION: In this study, we demonstrated that combined treatment with Th and WP modulates the BDNF-TrkB-CREB signaling pathway, resulting in downregulation of SERT expression and elevation of BDNF levels in the BO stress model. These molecular changes were accompanied by improved behavioral performance in mice subjected to stress and cognitive assessments. Our findings highlight the potential of Th + WP as non-pharmacological interventions for stress reduction and cognitive enhancement. Additionally, correlation analysis revealed a strong association in SERT expression between the BO and mouse stress models, further supporting cross-model consistency. SIGNIFICANCE STATEMENT: We established the novel human brain organoid-stress model, and coupled with mouse-stress model, we elucidated the synergistic actions of Th and WP in mitigating stress and augmenting cognitive function. Their effects were demonstrated to through the regulation of SERT, BDNF as well as the BDNF-TrkB-CREB pathway. This study presented a promising non-pharmacological avenue for mental health care. In addition, species differences between humans and mice were also examined through correlation analysis involving brain organoid and mouse models.
-
Ascorbic Acid Ameliorates Molecular and Developmental Defects in Human-Induced Pluripotent Stem Cell and Cerebral Organoid Models of Fragile X Syndrome.
Fragile X Syndrome (FX) is the most common form of inherited cognitive impairment and falls under the broader category of Autism Spectrum Disorders (ASD). FX is caused by a CGG trinucleotide repeat expansion in the non-coding region of the X-linked Fragile X Messenger Ribonucleoprotein 1 (FMR1) gene, leading to its hypermethylation and epigenetic silencing. Animal models of FX rely on the deletion of the Fmr1 gene, which fails to replicate the epigenetic silencing mechanism of the FMR1 gene observed in human patients. Human stem cells carrying FX repeat expansions have provided a better understanding of the basis of epigenetic silencing of FMR1. Previous studies have found that 5-Azacytidine (5Azac) can reverse this methylation; however, 5Azac can be toxic, which may limit its therapeutic potential. Here, we show that the dietary factor Ascorbic Acid (AsA) can reduce DNA methylation in the FMR1 locus and lead to an increase in FMR1 gene expression in FX iPSCs and cerebral organoids. In addition, AsA treatment rescued neuronal gene expression and morphological defects observed in FX iPSC-derived cerebral organoids. Hence, we demonstrate that the dietary co-factor AsA can partially revert the molecular and morphological defects seen in human FX models in vitro. Our findings have implications for the development of novel therapies for FX in the future.
-
Midbrain organoids mimic early embryonic neurodevelopment and recapitulate LRRK2-p.Gly2019Ser-associated gene expression.
Human brain organoid models that recapitulate the physiology and complexity of the human brain have a great potential for in vitro disease modeling, in particular for neurodegenerative diseases, such as Parkinson disease. In the present study, we compare single-cell RNA-sequencing data of human midbrain organoids to the developing human embryonic midbrain. We demonstrate that the in vitro model is comparable to its in vivo equivalents in terms of developmental path and cellular composition. Moreover, we investigate the potential of midbrain organoids for modeling early developmental changes in Parkinson disease. Therefore, we compare the single-cell RNA-sequencing data of healthy-individual-derived midbrain organoids to their isogenic LRRK2-p.Gly2019Ser-mutant counterparts. We show that the LRRK2 p.Gly2019Ser variant alters neurodevelopment, resulting in an untimely and incomplete differentiation with reduced cellular variability. Finally, we present four candidate genes, APP, DNAJC6, GATA3, and PTN, that might contribute to the LRRK2-p.Gly2019Ser-associated transcriptome changes that occur during early neurodevelopment.
-
Identifying gene expression programs of cell-type identity and cellular activity with single-cell RNA-Seq.
Identifying gene expression programs underlying both cell-type identity and cellular activities (e.g. life-cycle processes, responses to environmental cues) is crucial for understanding the organization of cells and tissues. Although single-cell RNA-Seq (scRNA-Seq) can quantify transcripts in individual cells, each cell's expression profile may be a mixture of both types of programs, making them difficult to disentangle. Here, we benchmark and enhance the use of matrix factorization to solve this problem. We show with simulations that a method we call consensus non-negative matrix factorization (cNMF) accurately infers identity and activity programs, including their relative contributions in each cell. To illustrate the insights this approach enables, we apply it to published brain organoid and visual cortex scRNA-Seq datasets; cNMF refines cell types and identifies both expected (e.g. cell cycle and hypoxia) and novel activity programs, including programs that may underlie a neurosecretory phenotype and synaptogenesis.
-
The CTNNBIP1-CLSTN1 fusion transcript regulates human neocortical development.
Fusion transcripts or RNAs have been found in both disordered and healthy human tissues and cells; however, their physiological functions in the brain development remain unknown. In the analysis of deposited RNA-sequence libraries covering early to middle embryonic stages, we identify 1,055 fusion transcripts present in the developing neocortex. Interestingly, 98 fusion transcripts exhibit distinct expression patterns in various neural progenitors (NPs) or neurons. We focus on CTNNBIP1-CLSTN1 (CTCL), which is enriched in outer radial glial cells that contribute to cortex expansion during human evolution. Intriguingly, downregulation of CTCL in cultured human cerebral organoids causes marked reduction in NPs and precocious neuronal differentiation, leading to impairment of organoid growth. Furthermore, the expression of CTCL fine-tunes Wnt/β-catenin signaling that controls cortex patterning. Together, this work provides evidence indicating important roles of fusion transcript in human brain development and evolution.
-
Psychiatry in a Dish: Stem Cells and Brain Organoids Modeling Autism Spectrum Disorders.
Autism spectrum disorders are a group of pervasive neurodevelopmental conditions with heterogeneous etiology, characterized by deficits in social cognition, communication, and behavioral flexibility. Despite an increasing scientific effort to find the pathophysiological explanations for the disease, the neurobiological links remain unclear. A large amount of evidence suggests that pathological processes taking place in early embryonic neurodevelopment might be responsible for later manifestation of autistic symptoms. This dysfunctional development includes altered maturation/differentiation processes, disturbances in cell-cell communication, and an unbalanced ratio between certain neuronal populations. All those processes are highly dependent on the interconnectivity and three-dimensional organizations of the brain. Moreover, in order to gain a deeper understanding of the complex neurobiology of autism spectrum disorders, valid disease models are pivotal. Induced pluripotent stem cells could potentially help to elucidate the complex mechanisms of the disease and lead to the development of more effective individualized treatment. The induced pluripotent stem cells approach allows comparison between the development of various cellular phenotypes generated from cell lines of patients and healthy individuals. A newly advanced organoid technology makes it possible to create three-dimensional in vitro models of brain development and structural interconnectivity, based on induced pluripotent stem cells derived from the respective individuals. The biggest challenge for modeling psychiatric diseases in vitro is finding and establishing the link between cellular and molecular findings with the clinical symptoms, and this review aims to give an overview over the feasibility and applicability of this new tissue engineering tool in psychiatry.