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Page 82 of 545-
Preclinical Studies with Glioblastoma Brain Organoid Co-Cultures Show Efficient 5-ALA Photodynamic Therapy.
BACKGROUND: The high recurrence of glioblastoma (GB) that occurs adjacent to the resection cavity within two years of diagnosis urges an improvement of therapies oriented to GB local control. Photodynamic therapy (PDT) has been proposed to cleanse infiltrating tumor cells from parenchyma to ameliorate short long-term progression-free survival. We examined 5-aminolevulinic acid (5-ALA)-mediated PDT effects as therapeutical treatment and determined optimal conditions for PDT efficacy without causing phototoxic injury to the normal brain tissue. METHODS: We used a platform of Glioma Initiation Cells (GICs) infiltrating cerebral organoids with two different glioblastoma cells, GIC7 and PG88. We measured GICs-5-ALA uptake and PDT/5-ALA activity in dose-response curves and the efficacy of the treatment by measuring proliferative activity and apoptosis. RESULTS: 5-ALA (50 and 100 µg/mL) was applied, and the release of protoporphyrin IX (PpIX) fluorescence measures demonstrated that the emission of PpIX increases progressively until its stabilization at 24 h. Moreover, decreased proliferation and increased apoptosis corroborated the effect of 5-ALA/PDT on cancer cells without altering normal cells. CONCLUSIONS: We provide evidence about the effectiveness of PDT to treat high proliferative GB cells in a complex in vitro system, which combines normal and cancer cells and is a useful tool to standardize new strategic therapies.
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De novo H3.3K27M-altered diffuse midline glioma in human brainstem organoids to dissect GD2 CAR T cell function.
Diffuse midline glioma (DMG) is a highly aggressive and untreatable pediatric cancer primarily arising in the pontine brainstem region, necessitating the development of representative models for treatment advance. Here we developed an FGF4-driven human brainstem organoid model, which we used to genetically engineer H3.3K27M-altered DMG. We demonstrated that brainstem pontine glial specification is critical for DMG tumorigenesis, yielding infiltrative tumors that recapitulate patient-representative intratumoral heterogeneity. Prolonged GD2 chimeric antigen receptor (CAR) T cell treatment mirrored clinical outcomes and revealed extensive transcriptional heterogeneity, from which both potent effector and dysfunctional CAR T cell populations could be identified. Furthermore, incorporation of myeloid cells generated DMG-specific microglia that reduced treatment efficacy and revealed CAR T cell functional states most vulnerable to microglia-mediated immunosuppression. Thus, we present a representative DMG model offering a months-long experimental window in vitro, which we leveraged to delineate CAR T cell functionality and microglial impact, aiding therapy development for this devastating disease.
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Human prefrontal cortex gene regulatory dynamics from gestation to adulthood at single-cell resolution.
Human brain development is underpinned by cellular and molecular reconfigurations continuing into the third decade of life. To reveal cell dynamics orchestrating neural maturation, we profiled human prefrontal cortex gene expression and chromatin accessibility at single-cell resolution from gestation to adulthood. Integrative analyses define the dynamic trajectories of each cell type, revealing major gene expression reconfiguration at the prenatal-to-postnatal transition in all cell types followed by continuous reconfiguration into adulthood and identifying regulatory networks guiding cellular developmental programs, states, and functions. We uncover links between expression dynamics and developmental milestones, characterize the diverse timing of when cells acquire adult-like states, and identify molecular convergence from distinct developmental origins. We further reveal cellular dynamics and their regulators implicated in neurological disorders. Finally, using this reference, we benchmark cell identities and maturation states in organoid models. Together, this captures the dynamic regulatory landscape of human cortical development.
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CTCF mutation at R567 causes developmental disorders via 3D genome rearrangement and abnormal neurodevelopment.
The three-dimensional genome structure organized by CTCF is required for development. Clinically identified mutations in CTCF have been linked to adverse developmental outcomes. Nevertheless, the underlying mechanism remains elusive. In this investigation, we explore the regulatory roles of a clinically relevant R567W point mutation, located within the 11th zinc finger of CTCF, by introducing this mutation into both murine models and human embryonic stem cell-derived cortical organoid models. Mice with homozygous CTCFR567W mutation exhibit growth impediments, resulting in postnatal mortality, and deviations in brain, heart, and lung development at the pathological and single-cell transcriptome levels. This mutation induces premature stem-like cell exhaustion, accelerates the maturation of GABAergic neurons, and disrupts neurodevelopmental and synaptic pathways. Additionally, it specifically hinders CTCF binding to peripheral motifs upstream to the core consensus site, causing alterations in local chromatin structure and gene expression, particularly at the clustered protocadherin locus. Comparative analysis using human cortical organoids mirrors the consequences induced by this mutation. In summary, this study elucidates the influence of the CTCFR567W mutation on human neurodevelopmental disorders, paving the way for potential therapeutic interventions.
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Pituitary Lineage Differentiation from Human Induced Pluripotent Stem Cells in 2D and 3D Cultures.
Despite its small size, the pituitary gland plays a central role in the maintenance of normal homeostasis of most physiological systems through its regulation of the function of other endocrine glands. The complexity of the anterior pituitary gland, due to its composition of several different hormone-secreting cell types, begets a plethora of disorders and pathologies due primarily to hyposecretion or hypersecretion of hormones. The gonadotrophs, which make up less than 5% of the total number of cells in the anterior pituitary, serve to regulate gonad development and sexual reproduction in males and females. Despite the increased research on the development of models to study pituitary function within the last decade, a model specifically designed to study the gonadotrophs is still lacking. The development of organoid technology has facilitated research in the field of personalized medicine and physiological testing using patient-derived cells. The ability to produce pituitary organoids would allow researchers to construct an in vitro model of the human hypothalamic-pituitary-gonadal or hypothalamic-pituitary-adrenal axis to use in further fertility or endocrine research. The application of this technology in patients could revolutionize the treatment of infertility and a variety of neuroendocrine disorders. The impetus behind this study was to develop a pituitary-like organoid consisting only of gonadotrophs. Despite the lack of success in differentiating gonadotrophs, pituitary-like organoids were differentiated from human-induced pluripotent stem cells. In addition, two-dimensional and three-dimensional differentiated cultures were characterized and compared to human adult cadaveric pituitary tissue.
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Improving cellular diversity in human cerebellar organoids.
The developing human cerebellum has a greater diversity of progenitor types than that of the mouse, necessitating a human-based model for studying cerebellar development and disease. Atamian et al.1 developed a 3D organoid model of cerebellar development, which recapitulates many cell types found in the developing human cerebellum, including Purkinje-neuron-like cells.
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Monosodium glutamate-induced lesions in the rat cingulate cortex.
The brains of neonate albino rats were examined with the light and electron microscope following subcutaneous administration of monosodium glutamate (MSG). In addition to lesions in areas known to be vulnerable to glutamate, such as the arcuate nucleus of the hypothalamus, distinct areas of necrotic tissue were detected in the granular portion of the retrosplenial cingulate cortex. The affected cells display the cytological features characteristic of MSG-lesioned brain tissue, including vacuolization of the endoplasmic reticulum and clumping of chromatin. Numerous pyknotic nuclei can be detected as early as 3 h following treatment. The possible causes of the lesion, particularly the role that may be played by astrocytes, are discussed.
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[Origin and formation of different types of vacuoles induced by the multiplication of the alphavirus Sindbis virus in various cell systems].
Spherule-containing vacuoles and nucleocapsid-bearing vacuoles (cytopathic vacuoles types 1 and 2 respectively of Grimley et al. 1968) induced by Alphavirus Sindbis were studied in brains from newborn mice, chicken embryo fibroblasts, and two lines of tumoral glial cells from muridae. Endoplasmic reticulum (ER) elements and finely granular electron-dense material also seen in contact with nucleocapsids seemed to be involved in the formation of the classical single-membrane spherule-containing vacuoles. A second type of spherule-containing vacuoles were characterized by their double membrane and an amorphous electron-dense content and were probably derived from mitochondria. Nucleocapsid-bearing vacuoles were formed from modified ER elements and seemed to be linked to excessive synthesis of viral material. Such ER alterations were not observed in RG6 cells. In these cells, there were only spherule-containing vacuoles, while nucleocapsids were seen associated with the cytoplasmic membrane only.
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Treating Parkinson's Disease with Human Bone Marrow Mesenchymal Stem Cell Secretome: A Translational Investigation Using Human Brain Organoids and Different Routes of In Vivo Administration.
Parkinson's disease (PD) is the most common movement disorder, characterized by the progressive loss of dopaminergic neurons from the nigrostriatal system. Currently, there is no treatment that retards disease progression or reverses damage prior to the time of clinical diagnosis. Mesenchymal stem cells (MSCs) are one of the most extensively studied cell sources for regenerative medicine applications, particularly due to the release of soluble factors and vesicles, known as secretome. The main goal of this work was to address the therapeutic potential of the secretome collected from bone-marrow-derived MSCs (BM-MSCs) using different models of the disease. Firstly, we took advantage of an optimized human midbrain-specific organoid system to model PD in vitro using a neurotoxin-induced model through 6-hydroxydopamine (6-OHDA) exposure. In vivo, we evaluated the effects of BM-MSC secretome comparing two different routes of secretome administration: intracerebral injections (a two-site single administration) against multiple systemic administration. The secretome of BM-MSCs was able to protect from dopaminergic neuronal loss, these effects being more evident in vivo. The BM-MSC secretome led to motor function recovery and dopaminergic loss protection; however, multiple systemic administrations resulted in larger therapeutic effects, making this result extremely relevant for potential future clinical applications.
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Neuronal defects in a human cellular model of 22q11.2 deletion syndrome.
22q11.2 deletion syndrome (22q11DS) is a highly penetrant and common genetic cause of neuropsychiatric disease. Here we generated induced pluripotent stem cells from 15 individuals with 22q11DS and 15 control individuals and differentiated them into three-dimensional (3D) cerebral cortical organoids. Transcriptional profiling across 100 days showed high reliability of differentiation and revealed changes in neuronal excitability-related genes. Using electrophysiology and live imaging, we identified defects in spontaneous neuronal activity and calcium signaling in both organoid- and 2D-derived cortical neurons. The calcium deficit was related to resting membrane potential changes that led to abnormal inactivation of voltage-gated calcium channels. Heterozygous loss of DGCR8 recapitulated the excitability and calcium phenotypes and its overexpression rescued these defects. Moreover, the 22q11DS calcium abnormality could also be restored by application of antipsychotics. Taken together, our study illustrates how stem cell derived models can be used to uncover and rescue cellular phenotypes associated with genetic forms of neuropsychiatric disease.