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Validation of non-destructive morphology-based selection of cerebral cortical organoids by paired morphological and single-cell RNA-seq analyses.
Organoids, self-organized cell aggregates, contribute significantly to developing disease models and cell-based therapies. Organoid-to-organoid variations, however, are inevitable despite the use of the latest differentiation protocols. Here, we focused on the morphology of organoids formed in a cerebral organoid differentiation culture and assessed their cellular compositions by single-cell RNA sequencing analysis. The data revealed that organoids primarily composed of non-neuronal cells, such as those from the neural crest and choroid plexus, showed unique morphological features. Moreover, we demonstrate that non-destructive morphological analysis can accurately distinguish organoids composed of cerebral cortical tissues from other cerebral tissues, thus enhancing experimental accuracy and reliability to ensure the safety of cell-based therapies.
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Prediction of the hypothalamus-pituitary organoid formation using machine learning.
Multi-cellular organoids are self-assembly aggregates that mimic biological functions and developmental processes of many tissue types in vitro. They are widely employed for disease modeling and functional studies. Hypothalamus-pituitary organoids can be generated through differentiation induction from pluripotent stem cells. However, their maturation is time consuming and labor intensive, and the quality of the resulting organoids can vary. Here, we developed a machine learning model capable of accurately predicting the successful generation of high-quality hypothalamus-pituitary organoids based solely on phase-contrast images captured during the early stage of differentiation. The model achieved an accuracy of 79% using images from organoids on day 9 to predict pituitary cell differentiation at day 40. Moreover, the computational approach identified the shape of the organoid surface as a critical determining factor that significantly affected the prediction. This model can help to enhance the efficiency of organoid induction experiments and illuminate the molecular mechanisms involved in hypothalamus-pituitary differentiation.
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Generation and utility of endocrine functional testicular organoids.
Male infertility is increasing in prevalence due to cancer treatment, environmental exposures, and patient-specific syndromes. Traditional two-dimensional culture systems inadequately recapitulate the complex three-dimensional architecture, microenvironment, and endocrine milieu essential for spermatogenesis. Testicular organoid models aim to circumvent the challenges of two-dimensional culture, mimicking key aspects of the testicular microenvironment, while enabling controlled experimental manipulation and patient-specific disease modeling. Current testicular organoids demonstrate remarkable preservation of endocrine function, including sustained testosterone and inhibin B production over as great as 12-week culture periods, while maintaining gonadotropin responsiveness that mirrors the pituitary-gonadal axis regulation a testis would experience in vivo. Testicular organoids have recently been used for drug and toxicity screening, and patient-specific organoids from men with nonobstructive azoospermia and Klinefelter syndrome have been explored for disease-relevant characteristics, providing a platform for personalized medicine approaches. Despite these significant advances, achieving complete functional spermatogenesis remains challenging. Limitations include high variability in tubular morphogenesis, with significant methodologic differences across research groups, constraining reproducibility. The primary cellular actor(s) driving this phenomenon is still under investigation. Emerging opportunities at the convergence of bioengineering fabrication techniques and stem cell biology may bridge these challenges, improving microtissue vascularization, advancing scalability, and adding options for patient-personalized experiments. In this review, recent progress in testicular organoid generation, utility for endocrine investigation, remaining technical challenges, and future scientific opportunities are specifically explored. Testicular organoids provide a promising in vitro model for the study of testicular morphogenesis and spermatogenesis, testicular endocrine signaling, and male factor infertility.
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Neural stem cells derived from human midbrain organoids as a stable source for treating Parkinson's disease: Midbrain organoid-NSCs (Og-NSC) as a stable source for PD treatment.
Successful clinical translation of stem cell-based therapy largely relies on the scalable and reproducible preparation of donor cells with potent therapeutic capacities. In this study, midbrain organoids were yielded from human pluripotent stem cells (hPSCs) to prepare cells for Parkinson's disease (PD) therapy. Neural stem/precursor cells (NSCs) isolated from midbrain organoids (Og-NSCs) expanded stably and differentiated into midbrain-type dopamine(mDA) neurons, and an unprecedentedly high proportion expressed midbrain-specific factors, with relatively low cell line and batch-to-batch variations. Single cell transcriptome analysis followed by in vitro assays indicated that the majority of cells in the Og-NSC cultures are ventral midbrain (VM)-patterned with low levels of cellular senescence/aging and mitochondrial stress, compared to those derived from 2D-culture environments. Notably, in contrast to current methods yielding mDA neurons without astrocyte differentiation, mDA neurons that differentiated from Og-NSCs were interspersed with astrocytes as in the physiologic brain environment. Thus, the Og-NSC-derived mDA neurons exhibited improved synaptic maturity, functionality, resistance to toxic insults, and faithful expressions of the midbrain-specific factors, in vitro and in vivo long after transplantation. Consequently, Og-NSC transplantation yielded potent therapeutic outcomes that are reproducible in PD model animals. Collectively, our observations demonstrate that the organoid-based method may satisfy the demands needed in the clinical setting of PD cell therapy.
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Human fetal brain self-organizes into long-term expanding organoids.
Human brain development involves an orchestrated, massive neural progenitor expansion while a multi-cellular tissue architecture is established. Continuously expanding organoids can be grown directly from multiple somatic tissues, yet to date, brain organoids can solely be established from pluripotent stem cells. Here, we show that healthy human fetal brain in vitro self-organizes into organoids (FeBOs), phenocopying aspects of in vivo cellular heterogeneity and complex organization. FeBOs can be expanded over long time periods. FeBO growth requires maintenance of tissue integrity, which ensures production of a tissue-like extracellular matrix (ECM) niche, ultimately endowing FeBO expansion. FeBO lines derived from different areas of the central nervous system (CNS), including dorsal and ventral forebrain, preserve their regional identity and allow to probe aspects of positional identity. Using CRISPR-Cas9, we showcase the generation of syngeneic mutant FeBO lines for the study of brain cancer. Taken together, FeBOs constitute a complementary CNS organoid platform.
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An Organoid-Based Model of Cortical Development Identifies Non-Cell-Autonomous Defects in Wnt Signaling Contributing to Miller-Dieker Syndrome.
Miller-Dieker syndrome (MDS) is caused by a heterozygous deletion of chromosome 17p13.3 involving the genes LIS1 and YWHAE (coding for 14.3.3ε) and leads to malformations during cortical development. Here, we used patient-specific forebrain-type organoids to investigate pathological changes associated with MDS. Patient-derived organoids are significantly reduced in size, a change accompanied by a switch from symmetric to asymmetric cell division of ventricular zone radial glia cells (vRGCs). Alterations in microtubule network organization in vRGCs and a disruption of cortical niche architecture, including altered expression of cell adhesion molecules, are also observed. These phenotypic changes lead to a non-cell-autonomous disturbance of the N-cadherin/β-catenin signaling axis. Reinstalling active β-catenin signaling rescues division modes and ameliorates growth defects. Our data define the role of LIS1 and 14.3.3ε in maintaining the cortical niche and highlight the utility of organoid-based systems for modeling complex cell-cell interactions in vitro.
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Blood-brain-barrier organoids for investigating the permeability of CNS therapeutics.
In vitro models of the blood-brain barrier (BBB) are critical tools for the study of BBB transport and the development of drugs that can reach the CNS. Brain endothelial cells grown in culture are often used to model the BBB; however, it is challenging to maintain reproducible BBB properties and function. 'BBB organoids' are obtained following coculture of endothelial cells, pericytes and astrocytes under low-adhesion conditions. These organoids reproduce many features of the BBB, including the expression of tight junctions, molecular transporters and drug efflux pumps, and hence can be used to model drug transport across the BBB. This protocol provides a comprehensive description of the techniques required to culture and maintain BBB organoids. We also describe two separate detection approaches that can be used to analyze drug penetration into the organoids: confocal fluorescence microscopy and mass spectrometry imaging. Using our protocol, BBB organoids can be established within 2-3 d. An additional day is required to analyze drug permeability. The BBB organoid platform represents an accurate, versatile and cost-effective in vitro tool. It can easily be scaled to a high-throughput format, offering a tool for BBB modeling that could accelerate therapeutic discovery for the treatment of various neuropathologies.
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Brain organoids for hypoxic-ischemic studies: from bench to bedside.
Our current knowledge regarding the development of the human brain mostly derives from experimental studies on non-human primates, sheep, and rodents. However, these studies may not completely simulate all the features of human brain development as a result of species differences and variations in pre- and postnatal brain maturation. Therefore, it is important to supplement the in vivo animal models to increase the possibility that preclinical studies have appropriate relevance for potential future human trials. Three-dimensional brain organoid culture technology could complement in vivo animal studies to enhance the translatability of the preclinical animal studies and the understanding of brain-related disorders. In this review, we focus on the development of a model of hypoxic-ischemic (HI) brain injury using human brain organoids to complement the translation from animal experiments to human pathophysiology. We also discuss how the development of these tools provides potential opportunities to study fundamental aspects of the pathophysiology of HI-related brain injury including differences in the responses between males and females.
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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.
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A Survey of the Metabolic Landscape of the Developing Cerebellum at Single-Cell Resolution.
The use of cell-culture models to investigate development and disease of the cerebellum is a recent advance, facilitated by the discovery that patterning of precursors is capable of giving rise to cells with specific neuronal identity. Pluripotent stem cell-derived organoids, which exhibit self-organisational characteristics reminiscent of early cerebellar tissue, present a number of challenges including recapitulation of conditions resembling the mature brain. An understanding of the processes driving fetal and postnatal maturation is required to reproduce these conditions in vitro and advance the capability of the system to model adult-onset disease. A key tool for achieving this is single-cell RNA sequencing, which enables visualisation of key transcriptional features of subpopulations comprising tissues. Here, we explore and compare available single-cell RNA sequencing data derived from the developing human cerebellum and its synthetic, in vitro counterpart (stem cell-derived cerebellar organoids). We focus on performing a qualitative assessment of the expression of key metabolic pathway genes, given recent findings exemplifying tissue-specific metabolic activity, including hypoxia and metabolic shifts associated with neuronal expansion. Signatures indicative of known cell type-specific metabolic differences, such as the astrocyte-neuron lactate shuttle and glutamate-glutamine cycle were evident at a transcriptional level. Cerebellar tissue and cerebellar organoids showed a number of behavioural similarities, including HIF1 signalling, which may serve to drive expansion of granule cell progenitors in both settings. We further highlight numerous differences between cultured organoids and native tissue which may provide clarity on the state of metabolic state following differentiation of organoids, providing the future framework to test and further hypotheses regarding promoting maturation. Overall, this analysis provides insight into understanding the state of in vitro models of the cerebellum, a critical factor required for modelling susceptibility of various cell types to cerebellar disease.