Your browser does not allow saving data (e.g. private mode): bookmarks will be lost when the tab closes.
Search PubMed
Keywords, author, journal, years — results from PubMed, abstracts with Russian translation, bookmarks in your browser.
Found: 5 450
Page 84 of 545-
Chimeric brain models: Unlocking insights into human neural development, aging, diseases, and cell therapies.
Human-rodent chimeric brain models serve as a unique platform for investigating the pathophysiology of human cells within a living brain environment. These models are established by transplanting human tissue- or human pluripotent stem cell (hPSC)-derived macroglial, microglial, or neuronal lineage cells, as well as cerebral organoids, into the brains of host animals. This approach has opened new avenues for exploring human brain development, disease mechanisms, and regenerative processes. Here, we highlight recent advancements in using chimeric models to study human neural development, aging, and disease. Additionally, we explore the potential applications of these models for studying human glial cell-replacement therapies, studying in vivo human glial-to-neuron reprogramming, and harnessing single-cell omics and advanced functional assays to uncover detailed insights into human neurobiology. Finally, we discuss strategies to enhance the precision and translational relevance of these models, expanding their impact in stem cell and neuroscience research.
-
2D and 3D Stem Cell Models of Primate Cortical Development Identify Species-Specific Differences in Progenitor Behavior Contributing to Brain Size.
Variation in cerebral cortex size and complexity is thought to contribute to differences in cognitive ability between humans and other animals. Here we compare cortical progenitor cell output in humans and three nonhuman primates using directed differentiation of pluripotent stem cells (PSCs) in adherent two-dimensional (2D) and organoid three-dimensional (3D) culture systems. Clonal lineage analysis showed that primate cortical progenitors proliferate for a protracted period of time, during which they generate early-born neurons, in contrast to rodents, where this expansion phase largely ceases before neurogenesis begins. The extent of this additional cortical progenitor expansion differs among primates, leading to differences in the number of neurons generated by each progenitor cell. We found that this mechanism for controlling cortical size is regulated cell autonomously in culture, suggesting that primate cerebral cortex size is regulated at least in part at the level of individual cortical progenitor cell clonal output.
-
Amyloid precursor protein elevates fusion of promyelocytic leukemia nuclear bodies in human hippocampal areas with high plaque load.
The amyloid precursor protein (APP) is a type I transmembrane protein with unknown physiological function but potential impact in neurodegeneration. The current study demonstrates that APP signals to the nucleus causing the generation of aggregates consisting of its adapter protein FE65, the histone acetyltransferase TIP60 and the tumour suppressor proteins p53 and PML. APP C-terminal (APP-CT50) complexes co-localize and co-precipitate with p53 and PML. The PML nuclear body generation is induced and fusion occurs over time depending on APP signalling and STED imaging revealed active gene expression within the complex. We further show that the nuclear aggregates of APP-CT50 fragments together with PML and FE65 are present in the aged human brain but not in cerebral organoids differentiated from iPS cells. Notably, human Alzheimer's disease brains reveal a highly significant reduction of these nuclear aggregates in areas with high plaque load compared to plaque-free areas of the same individual. Based on these results we conclude that APP-CT50 signalling to the nucleus takes place in the aged human brain and is involved in the pathophysiology of AD.
-
Corticothalamic assembloids recapitulate human fetal brain morphologies and enhance neuronal complexity.
Neuronal morphology governs how neurons connect, integrate, and process information, offering critical insights into the functional architecture of the brain. Characterizing the three-dimensional (3D) morphology of individual neurons is key not only for mapping circuit connectivity but also for understanding the cellular diversity that emerges during development. Neural organoids are valuable models of human brain development and disease, yet their morphological complexity remains poorly characterized despite advances in single-cell transcriptomics. Here, we use 3D confocal imaging and manual reconstruction of 735 neurons to analyze forebrain (dorsal and ventral) and thalamic (dorsal and ventral) organoids, as well as forebrain, thalamic, and corticothalamic assembloids. We find that organoids and assembloids exhibit distinct morphologies resembling fetal brain neurons, including immature pyramidal-like, double-bouquet, and bushy-like neurons. Interregional assembloids show greater neuronal morphological complexity than individual organoids, with more extensive dendritic branching, longer projections, and diverse soma shapes. Corticothalamic assembloids further display features of emerging connectivity. Complementary transcriptomic profiling supports regional identity and reveals expression of genes involved in projection guidance. We observe dendritic spines with excitatory and inhibitory profiles and varicosities, indicative of maturing synaptic architecture. Together, our work makes an initial effort in describing the diversity of neuronal morphology in human neural organoids and assembloids. It further establishes structural phenotyping as a critical dimension for validating human neural models and underscores their value for modeling morphofunctional disorders.
-
Embryonic origin of two ASD subtypes of social symptom severity: the larger the brain cortical organoid size, the more severe the social symptoms.
BACKGROUND: Social affective and communication symptoms are central to autism spectrum disorder (ASD), yet their severity differs across toddlers: Some toddlers with ASD display improving abilities across early ages and develop good social and language skills, while others with "profound" autism have persistently low social, language and cognitive skills and require lifelong care. The biological origins of these opposite ASD social severity subtypes and developmental trajectories are not known. METHODS: Because ASD involves early brain overgrowth and excess neurons, we measured size and growth in 4910 embryonic-stage brain cortical organoids (BCOs) from a total of 10 toddlers with ASD and 6 controls (averaging 196 individual BCOs measured/subject). In a 2021 batch, we measured BCOs from 10 ASD and 5 controls. In a 2022 batch, we tested replicability of BCO size and growth effects by generating and measuring an independent batch of BCOs from 6 ASD and 4 control subjects. BCO size was analyzed within the context of our large, one-of-a-kind social symptom, social attention, social brain and social and language psychometric normative datasets ranging from N = 266 to N = 1902 toddlers. BCO growth rates were examined by measuring size changes between 1- and 2-months of organoid development. Neurogenesis markers at 2-months were examined at the cellular level. At the molecular level, we measured activity and expression of Ndel1; Ndel1 is a prime target for cell cycle-activated kinases; known to regulate cell cycle, proliferation, neurogenesis, and growth; and known to be involved in neuropsychiatric conditions. RESULTS: At the BCO level, analyses showed BCO size was significantly enlarged by 39% and 41% in ASD in the 2021 and 2022 batches. The larger the embryonic BCO size, the more severe the ASD social symptoms. Correlations between BCO size and social symptoms were r = 0.719 in the 2021 batch and r = 0. 873 in the replication 2022 batch. ASD BCOs grew at an accelerated rate nearly 3 times faster than controls. At the cell level, the two largest ASD BCOs had accelerated neurogenesis. At the molecular level, Ndel1 activity was highly correlated with the growth rate and size of BCOs. Two BCO subtypes were found in ASD toddlers: Those in one subtype had very enlarged BCO size with accelerated rate of growth and neurogenesis; a profound autism clinical phenotype displaying severe social symptoms, reduced social attention, reduced cognitive, very low language and social IQ; and substantially altered growth in specific cortical social, language and sensory regions. Those in a second subtype had milder BCO enlargement and milder social, attention, cognitive, language and cortical differences. LIMITATIONS: Larger samples of ASD toddler-derived BCO and clinical phenotypes may reveal additional ASD embryonic subtypes. CONCLUSIONS: By embryogenesis, the biological bases of two subtypes of ASD social and brain development-profound autism and mild autism-are already present and measurable and involve dysregulated cell proliferation and accelerated neurogenesis and growth. The larger the embryonic BCO size in ASD, the more severe the toddler's social symptoms and the more reduced the social attention, language ability, and IQ, and the more atypical the growth of social and language brain regions.
-
ASD mutations in the ciliary gene CEP41 impact development of projection neurons and interneurons in a human cortical organoid model.
Primary cilia control cell-cell signalling and their dysfunction has been implicated in Autism Spectrum Disorders (ASD) but their roles in the ASD aetiology remain largely unexplored. Here, we analysed the impact of ASD mutations in CEP41 using human cortical organoids. CEP41 encodes a centrosomal protein located at the basal body and the ciliary axoneme and is mutated in ASD individuals and in Joubert syndrome, a ciliopathy with high incidence of ASD. To gain insights into CEP41's role in ASD aetiology, we characterised human cortical organoids carrying the CEP41 R242H point mutations found in ASD individuals. This mutation did not interfere with CEP41's ciliary localisation but cilia were shorter and had lower levels of tubulin polyglutamylation, which is indicative of altered cilia stability and signalling. Moreover, scRNAseq analyses revealed that the expression of several transcription factors with critical roles in interneuron development was altered in mutant interneurons and their progenitors. The CEP41 mutation also caused an augmented formation of upper layer cortical neurons. Taken together, these findings indicate that CEP41 controls excitatory and inhibitory neuron differentiation, alterations in which might lead to an excitation/inhibition imbalance that is widely recognized as a convergent mechanism underlying neurodevelopmental disorders.
-
A polarized FGF8 source specifies frontotemporal signatures in spatially oriented cell populations of cortical assembloids.
Organoids generating major cortical cell types in distinct compartments are used to study cortical development, evolution and disorders. However, the lack of morphogen gradients imparting cortical positional information and topography in current systems hinders the investigation of complex phenotypes. Here, we engineer human cortical assembloids by fusing an organizer-like structure expressing fibroblast growth factor 8 (FGF8) with an elongated organoid to enable the controlled modulation of FGF8 signaling along the longitudinal organoid axis. These polarized cortical assembloids mount a position-dependent transcriptional program that in part matches the in vivo rostrocaudal gene expression patterns and that is lost upon mutation in the FGFR3 gene associated with temporal lobe malformations and intellectual disability. By producing spatially oriented cell populations with signatures related to frontal and temporal area identity within individual assembloids, this model recapitulates in part the early transcriptional divergence embedded in the protomap and enables the study of cortical area-relevant alterations underlying human disorders.
-
The pathogenesis of transmissible spongiform encephalopathy: an ultrastructural study.
The brains of 9 spider monkeys, inoculated intracerebrally with brain suspension from kuru patients and of 3 normal control monkeys have been studied. All the animals were killed by perfusion with fixative, 8 during early incubation (ranging from 2 to 40 weeks) when healthy and free from neurological signs, one after 122 weeks when the disease was fully established. The most striking feature seen in every brain between the incubation times of 4 and 40 weeks was the formation of multilaminated membranes (ACPMs). These affected stretches of two apposed, mostly neuronal, plasma membranes over variable distances and created the impression of complex ribbon-or cord-like junctions. Their number varied with the length of incubation, reaching a peak at 13 weeks and declining thereafter. ACPMs were found throughout the grey matter, but they were most numerous in phylogenetically older regions of the brain, regions which also show the severest lesions in human kuru. It is suggested that ACPMs are initially due to an excessive synthesis of some membrane constituent by the perikaryon and various possibilities for their genesis are discussed. The hypothesis is advanced that they may be due to the reactivation of embryonic growth mechanisms and represent abortive junctions which, being formed in mature neurons, take a rather bizarre shape. Other changes such as the formation of somatic spines, an excessive number of dendritic spines including a high proportion with long tortuous necks, and the presence of binucleated neurons and numerous growth cones, point to the similarly immature pattern and would support this hypothesis. The material provided ample evidence that ACPMs, which can occupy as much as 26 per cent of a dendritic surface, give rise to intracytoplasmic vacuoles, which may therefore be regarded as secondary to a primary change in the permeability of the plasma membrane at the site of ACPMs. Individual single vacuoles could often build up into complex soap-bubble-like arrays, which were interpreted as the ultrastructural equivalent of histological status spongiosus. There is some evidence that the development of status spongiosus in other transmissible spongiform encephalopathies follows the same pattern.
-
Use of induced pluripotent stem cells (iPSCs) and cerebral organoids in modeling the congenital infection and neuropathogenesis induced by Zika virus.
Infection with Zika virus (ZIKV) was recently demonstrated to be associated with damage to the central nervous system, especially microcephaly and the Guillain-Barré syndrome. This finding had alarmed public health agencies and mobilized institutions around the world to search for more information about the virus, its effects, pathophysiological mechanisms, and potential immunizations and treatments. Given the increasing interest in using iPSCs and cerebral organoids to model the congenital infection and neuropathogenesis induced by ZIKV, the aim of this review was to present an up-to-date summary of the publications on the association of ZIKV with microcephaly, using iPSCs and organoids. According to our review, the number of studies has decreased concomitantly with a decrease in the number of cases. The presence of subclinical lesions at birth, which may eventually present cognitive or behavioral problems in the future, suggests that persistent research efforts on the virus should be undertaken by the global health community till the threat is completely wiped out.
-
Patient-derived organoid model of olfactory ensheathing cell tumor.
We developed a culture model of a human olfactory ensheathing cell tumor. Cultured organoids resemble normal ensheathing cells. Assays suggest that this model provides a tool for studying the roles of these glial cells in the maintenance of the peripheral olfactory system.