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A novel iPSC model of Bryant-Li-Bhoj neurodevelopmental/neurodegenerative syndrome demonstrates the role of histone H3.3 in chromatin dynamics, neuronal differentiation, and maturation.
BACKGROUND: Bryant-Li-Bhoj neurodevelopmental syndrome (BLBS) is neurogenetic disorder caused by variants in H3-3A and H3-3B, the two genes that encode histone H3.3. Ninety-nine percent of individuals with BLBS show developmental delay/intellectual disability, but the mechanism by which variants in H3.3 result in these phenotypes is not yet understood, limiting the therapeutic interventions available to individuals living with BLBS. METHODS: Here, we investigate how one BLBS-causative variant, H3-3B p.Leu48Arg (L48R), affects neurodevelopment using an induced pluripotent stem cell model differentiated to 2D neural progenitor cells (NPCs), 2D forebrain neurons (FBNs), and 3D dorsal forebrain organoids (DFBOs). We employ a multi-omic approach in the 2D models to quantify the resulting changes in gene expression and chromatin accessibility. We used immunofluorescence (IF) staining to define the identities of cells in the 3D DFBOs and whole-cell patch clamp to investigate the electrophysiological properties of neurons in DFBOs. RESULTS: In the 2D systems, we found dysregulated gene expression and chromatin accessibility affecting neuronal fate, adhesion, neurotransmission, and excitatory/inhibitory balance. Immunofluorescence of DFBOs corroborated altered proportions of radial glia and mature neuronal populations. Patch clamp recordings revealed decreased electrical activity in neurons from L48R DFBOs compared to control DFBOs. CONCLUSIONS: These data provide the first mechanistic insights into the pathogenesis of BLBS from a human-derived model of neurodevelopment, which suggest that H3.3 L48R increases H3-3B expression, resulting in the hyper-deposition of H3.3 into the nucleosome, which underlies changes in gene expression and chromatin accessibility. Functionally, this causes dysregulation of cell adhesion, neurotransmission, and the balance between excitatory and inhibitory signaling. These results are a crucial step towards preclinical development and testing of targeted therapies for this and related disorders.
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Modeling axonal regeneration by changing cytoskeletal dynamics in stem cell-derived motor nerve organoids.
Oxidative stress triggers axon degeneration and cell death, leading to the development of neurodegenerative diseases. Spinal motor nerves project very long axons, increasing the burden on axonal transport and metabolism. As such, spinal motor nerves are expected to be susceptible to oxidative stress, but model systems for visualizing and investigating acutely degenerating motor axons are limited. In this study, we establish motor nerve organoids from human pluripotent stem cells (hPSCs) with properties similar to those of neuromesodermal progenitors (NMPs), a population of progenitor cells that comprise the caudal spinal cord. Three-dimensional differentiation of organoids efficiently gave rise to mature motor neurons within 18 days. Adherent organoids showed robust axon fascicles and active growth cones under normal conditions. In addition, more homogenous and efficient generation of motor neurons were achieved when organoids were dissociated into individual cells. Hydrogen peroxide-induced oxidative stress resulted in a broad range of signs of axon degeneration including the disappearance of growth cones and neurites, axon retraction, axon fragmentation and bleb formation, and apoptotic cell death, whose severity can be reliably quantifiable in our culture system. Remarkably, cytoskeletal drugs modulating actin or microtubule turnover differentially facilitated axon dynamics and increased axon regenerative potential. Taken together, our motor nerve organoid model could be potentially useful for drug screens evaluating the rearrangement of cytoskeletons in regenerating motor axons.
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Organoids: An intermediate modeling platform in precision oncology.
Cancer harbors variable heterogeneity and plasticity. Thus far, our comprehension is greatly based on cell lines, organoids, and patient-derived tumor xenografts (PDTXs). Organoids are a three-dimensional in vitro culture platform constructed from self-organizing stem cells. They can almost accurately recapitulate tumor heterogeneity and microenvironment "in a dish," which surpass established cell lines and are not as expensive and time-consuming as PDTXs. As an intermediate model, tumor organoids are also used to study the fundamental issues of tumorigenesis and metastasis. They are specifically applied for drug testing and stored as "living biobanks." In this review, we highlight the translational applications of organoid technologies in tumor research and precision medicine, discuss the advantages and limitations compared with other mentioned methods, and provide our outlook on its future.
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Induced Pluripotent Stem Cells Derived Cellular Models for Investigating Parkinson's Disease Pathogenesis and Drug Screening.
Parkinson's disease (PD) is the second most common neurodegenerative disorder, affecting millions worldwide. The complexity of PD has hindered the development of accurate disease models. Induced pluripotent stem cells (iPSCs), derived from patient-specific cells, offer a promising platform for modeling PD. This review discusses the development of PD models using iPSCs from different patient sources, focusing on 2D and 3D culture systems. We also explore the integration of iPSCs with advanced technologies like multi-omics, tissue engineering, and gene editing, and their potential to drive breakthroughs in disease modeling. Co-culture systems of iPSC-derived neurons and glial cells provide insights into cell-cell interactions in PD, while 3D brain region-specific organoids enhance understanding of interregional disease processes. Advances in multi-omics and gene editing have further propelled iPSC-based disease modeling, offering new avenues for investigating disease mechanisms and therapeutic screening.
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Cerebral-Organoid-Derived Exosomes Alleviate Oxidative Stress and Promote LMX1A-Dependent Dopaminergic Differentiation.
The remarkable advancements related to cerebral organoids have provided unprecedented opportunities to model human brain development and diseases. However, despite their potential significance in neurodegenerative diseases such as Parkinson's disease (PD), the role of exosomes from cerebral organoids (OExo) has been largely unknown. In this study, we compared the effects of OExo to those of mesenchymal stem cell (MSC)-derived exosomes (CExo) and found that OExo shared similar neuroprotective effects to CExo. Our findings showed that OExo mitigated H2O2-induced oxidative stress and apoptosis in rat midbrain astrocytes by reducing excess ROS production, antioxidant depletion, lipid peroxidation, mitochondrial dysfunction, and the expression of pro-apoptotic genes. Notably, OExo demonstrated superiority over CExo in promoting the differentiation of human-induced pluripotent stem cells (iPSCs) into dopaminergic (DA) neurons. This was attributed to the higher abundance of neurotrophic factors, including neurotrophin-4 (NT-4) and glial-cell-derived neurotrophic factor (GDNF), in OExo, which facilitated the iPSCs' differentiation into DA neurons in an LIM homeobox transcription factor 1 alpha (LMX1A)-dependent manner. Our study provides novel insight into the biological properties of cerebral organoids and highlights the potential of OExo in the treatment of neurodegenerative diseases such as PD.
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Inhibition of the bromodomain and extra-terminal family of epigenetic regulators as a promising therapeutic approach for gastric cancer.
PURPOSE: Epigenetic dysregulation is a common characteristic of cancers, including gastric cancer (GC), and contributes to cancer development and progression. Although the efficacy of BET (an epigenetic regulator) inhibition has been demonstrated in various cancer types, predictive genetic markers of its efficacy in GC are currently lacking. Therefore, we aimed to identify markers that predict the response of BET inhibition in GC and, suggest an effective treatment regimen through combined therapy. METHODS: The effect of BET inhibition was evaluated using iBET-151, a small-molecule inhibitor of BET proteins, in a large panel (n = 49) of GC cell lines and xenograft mouse models. Comprehensive genetic information was used to identify cell lines sensitive to iBET-151. Flow cytometry, Western blotting, and colony-formation and migration assays were used to evaluate the effects of iBET-151 and/or paclitaxel. The synergistic effect of iBET-151 and paclitaxel was evaluated using an organoid model. RESULTS: We found that iBET-151 showed a modest growth-inhibitory effect in GC cells (73%, 36/49). iBET-151 inhibited tumorigenicity in vitro and significantly promoted cell cycle arrest and apoptosis. Based on comprehensive genetic information analysis in relation to BET family expression, we found that BRD4 was highly expressed in the iBET-151-sensitive cell lines. We also identified WNT5B and IRS2 as potential biomarkers that are predictive for sensitivity to iBET-151. In GC xenograft model mice, iBET-151 significantly decreased tumor volumes and Ki-67 and BRD4 expression. Combination treatment showed that iBET-151 increased the sensitivity of GC cells to paclitaxel in approximately 70% of the cell lines (34/49) tested. iBET-151 plus paclitaxel significantly promoted cell cycle arrest and apoptosis and suppressed c-Myc, Bcl-2 and Bcl-xL expression. In GC organoids, iBET-151 and paclitaxel showed a synergistic effect. CONCLUSIONS: Collectively, our data suggest that iBET-151 is a potential therapeutic agent for GC, especially in combination with paclitaxel, and that WNT5B and IRS2 may predict iBET-151 sensitivity.
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Electroacoustic Responsive Cochlea-on-a-Chip.
Organ-on-chips can highly simulate the complex physiological functions of organs, exhibiting broad application prospects in developmental research, disease simulation, as well as new drug research and development. However, there is still less concern about effectively constructing cochlea-on-chips. Here, a novel cochlear organoids-integrated conductive hydrogel biohybrid system with cochlear implant electroacoustic stimulation (EAS) for cochlea-on-a-chip construction and high-throughput drug screening, is presented. Benefiting from the superior biocompatibility and electrical property of conductive hydrogel, together with cochlear implant EAS, the inner ear progenitor cells can proliferate and spontaneously shape into spheres, finally forming cochlear organoids with good cell viability and structurally mature hair cells. By incorporating these progenitor cells-encapsulated hydrogels into a microfluidic-based cochlea-on-a-chip with culture chambers and a concentration gradient generator, a dynamic and high-throughput evaluation of inner ear disease-related drugs is demonstrated. These results indicate that the proposed cochlea-on-a-chip platform has great application potential in organoid cultivation and deafness drug evaluation.
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Organoids: Avatars for Personalized Medicine.
Stem cells are the foundation of all mammalian life. Stem cells build and maintain our bodies throughout life. Two types of stem cells are discerned.1) Embryonic stem cells (ES cells) are briefly present in the early human or mouse embryo, a few days after fertilization. These ES cells can be grown indefinitely in the lab and have the potential to build each and every tissue in our body. Because of this 'pluripotency', ES cells hold great promise for therapeutic application in the field of regenerative medicine. It is also possible to take skin cells (or other cells) from adults and convert these in the lab into cells with ES properties, so called iPS cells. Many of the hurdles that ES cell technology have faced, do not exist for iPS cells.2) Adult stem cells. Every organ in our body is believed to harbor its own dedicated stem cells. These adult stem cells replace tissue that is lost due to wear and tear, trauma and disease. Adult stem cells are highly specialized and can only produce the tissue in which they reside; they are 'multipotent'. Examples are bone marrow stem cells that make all blood cells, skin stem cells and gut stem cells. Even the brain is now known to harbor its specialized stem cells. The adult stem cells allow us to live 80-90 years, but this comes at a cost: they are the cells that most easily transform into cancer cells.Both types of stem cells can be used to establish 'organoids', 3D structures established in a dish, that recapitulate many aspects of the organ they represent. Pluripotent stem cells can be taken through the developmental steps that establish organs during embryogenesis. This has worked particularly well for parts of the the central nervous system, the kidney and GI organs. We have shown that adult epithelial stem cells carrying the generic Lgr5 marker can be cultured under tissue-repair conditions and generate epithelial organoids directly from healthy and diseased organs such as the gut, the liver, the lung and the pancreas. Organoid technology opens a range of avenues for the study of development, physiology and disease, for drug development and for personalized medicine. In the long run, cultured mini-organs may replace transplant organs from donors and hold promise in gene therapy.
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Elucidating Tumorigenesis Mechanisms and Assessing Immunotherapeutic Efficacy in Patient-Derived Medulloblastoma Organoid Models.
Medulloblastoma is one of the most common malignant pediatric brain tumors. There remain significant challenges in investigating oncogenic mechanisms and evaluating therapeutic efficacy due to the limited available models that accurately reflect tumor heterogeneity. To overcome this limitation, we established 10 patient-derived medulloblastoma organoids (MBOs) that retain the histological characteristics, and cellular diversity of the original tumors. These MBOs demonstrate strong infiltration capabilities, both in vitro through co-culture with human embryonic stem cell-derived cerebral organoids and in vivo following orthotopic or subcutaneous transplantation, establishing a potential platform for investigating interactions within the tumor microenvironment. Using integrated RNA sequencing, whole-exome sequencing, and DNA methylation profiling, we demonstrated that MBOs faithfully preserve the transcriptional, genomic, and epigenetic landscapes of their parental tumors. Single-cell transcriptomic analysis revealed conserved cellular subpopulation between MBOs and primary tumors. Our findings suggest that photoreceptor-related pathways may play an unprecedented role in the pathogenesis of Group 4 medulloblastoma and may be associated with interactions within the tumor microenvironment. Furthermore, we developed a prognostic nomogram based on IMPG2, BNC2, PAPPA2, ITGBL1and UNC13C expression levels in tumor cells to predict survival outcomes. Notably, tumor-infiltrating lymphocytes (TILs) expanded from patient specimens exhibited significant cytotoxic activity against autologous MBOs co-cultured in vitro and effectively suppressed the growth of subcutaneous MBO xenografts in vivo. These findings demonstrate the potential of TIL-based immunotherapy for medulloblastoma treatment. Collectively, our MBO system faithfully recapitulates critical tumor characteristics and serves as a valuable platform for investigating tumorigenic mechanisms and assessing therapeutic responses. This study not only promotes fundamental biological research but also accelerates clinical translation in medulloblastoma.
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Tissue-Slice Organ-on-Chip Culture of Hypothalamic and Pituitary of Lambs─The Role of Phoenixin-20 as a Modulator of Gonadotrophic Axis.
This study aimed to reconstruct the hypothalamic-pituitary axis using an organ-on-a-chip (OOC) model and to evaluate the modulatory role of phoenixin-20 (PNX) in the regulation of the gonadotrophic axis in sheep. Sixteen female Polish Merino lambs were used as tissue donors to create microfluidic chips containing paired hypothalamic and pituitary slices connected via perfused channels. This system enabled continuous medium flow and maintenance of functional neuroendocrine interactions under ex vivo conditions. The OOC platform was used to analyze changes in the expression of gonadotropin-releasing hormone (GnRH), kisspeptin (Kiss), neurokinin B (NKB), and prodynorphin (pDYN) in the hypothalamus, as well as luteinizing hormone (LH) and follicle-stimulating hormone (FSH) expression and secretion in the pituitary. PNX treatment significantly increased hypothalamic GnRH expression, while the blockade of neuropeptide Y receptors (NPY1R and NPY5R) diminished this response, suggesting that PNX effects are at least partially mediated through NPY-dependent pathways. Moreover, PNX altered the transcription of Kiss, NKB, and pDYN, key components of the GnRH pulse generator, and modulated LHβ mRNA expression in the pituitary. Changes in the LH and FSH concentrations further supported a receptor-specific mechanism of PNX action. The developed hypothalamo-pituitary OOC model proved valuable for studying neuroendocrine control of reproduction. This system offers a physiologically relevant and ethically sustainable alternative to in vivo experiments, enabling precise investigations of molecular and hormonal mechanisms within the gonadotrophic axis.