Glial Progenitor Cells Research Articles

Direct Conversion of Human Stem Cell-Derived Glial Progenitor Cells into GABAergic Interneurons.

Glial progenitor cells are widely distributed in brain parenchyma and represent a suitable target for future therapeutic interventions that generate new neurons via in situ reprogramming. Previous studies have shown successful reprogramming of mouse glia into neurons whereas the conversion of human glial cells remains challenging due to the limited accessibility of human brain tissue. Here, we have used a recently developed stem cell-based model of human glia progenitor cells (hGPCs) for direct neural reprogramming by overexpressing a set of transcription factors involved in GABAergic interneuron fate specification. GABAergic interneurons play a key role in balancing excitatory and inhibitory neural circuitry in the brain and loss or dysfunction of these have been implicated in several neurological disorders such as epilepsy, schizophrenia, and autism. Our results demonstrate that hGPCs successfully convert into functional induced neurons with postsynaptic activity within a month. The induced neurons have properties of GABAergic neurons, express subtype-specific interneuron markers (e.g. parvalbumin) and exhibit a complex neuronal morphology with extensive dendritic trees. The possibility of inducing GABAergic interneurons from a renewable in vitro hGPC system could provide a foundation for the development of therapies for interneuron pathologies.

Glial restricted precursor cells in central nervous system disorders: Current applications and future perspectives.

The crosstalk between glial cells and neurons represents an exceptional feature for maintaining the normal function of the central nervous system (CNS). Increasing evidence has revealed the importance of glial progenitor cells in adult neurogenesis, reestablishment of cellular pools, neuroregeneration, and axonal (re)myelination. Several types of glial progenitors have been described, as well as their potentialities for recovering the CNS from certain traumas or pathologies. Among these precursors, glial-restricted precursor cells (GRPs) are considered the earliest glial progenitors and exhibit tripotency for both Type I/II astrocytes and oligodendrocytes. GRPs have been derived from embryos and embryonic stem cells in animal models and have maintained their capacity for self-renewal. Despite the relatively limited knowledge regarding the isolation, characterization, and function of these progenitors, GRPs are promising candidates for transplantation therapy and reestablishment/repair of CNS functions in neurodegenerative and neuropsychiatric disorders, as well as in traumatic injuries. Herein, we review the definition, isolation, characterization and potentialities of GRPs as cell-based therapies in different neurological conditions. We briefly discuss the implications of using GRPs in CNS regenerative medicine and their possible application in a clinical setting. MAIN POINTS: GRPs are progenitors present in the CNS with differentiation potential restricted to the glial lineage. These cells have been employed in the treatment of a myriad of neurodegenerative and traumatic pathologies, accompanied by promising results, herein reviewed.

Low-Field Magnetic Stimulation Accelerates the Differentiation of Oligodendrocyte Precursor Cells via Non-canonical TGF-β Signaling Pathways.

Demyelination and oligodendrocyte loss are characteristic changes in demyelinating disorders. Low-field magnetic stimulation (LFMS) is a novel transcranial neuromodulation technology that has shown promising therapeutic potential for a variety of neuropsychiatric conditions. The cellular and molecular mechanisms of magnetic stimulation remain unclear. Previous studies mainly focused on the effects of magnetic stimulation on neuronal cells. Here we aimed to examine the effects of a gamma frequency LFMS on the glial progenitor cells. We used rat central glia-4 (CG4) cell line as an in vitro model. CG4 is a bipotential glial progenitor cell line that can differentiate into either oligodendrocyte or type 2-astrocyte. The cells cultured in a defined differentiation media were exposed to a 40-Hz LFMS 20min daily for five consecutive days. We found that LFMS transiently elevated the level of TGF-β1 in the culture media in the first 24h after the treatment. In correlation with the TGF-β1 levels, the percentage of cells possessing complex branches and expressing the late oligodendrocyte progenitor marker O4 was increased, indicating the accelerated differentiation of CG4 cells towards oligodendrocyte in LFMS-treated cultures. LFMS increased phosphorylation of Akt and Erk1/2 proteins, but not SMAD2/3. TGF-β1 receptor I specific inhibitor LY 364947 partially suppressed the effects of LFMS on differentiation and on levels of pAkt and pErk1/2, indicating that LFMS enhances the differentiation of oligodendrocyte progenitor cells via activation of non-canonical TGF-β-Akt and TGF-β-Erk1/2 pathways but not the canonical SMAD pathway. The data from this study reveal a novel mechanism of magnetic stimulation as a potential therapy for demyelination disorders.

Direct Reprogramming of Human Fetal- and Stem Cell-Derived Glial Progenitor Cells into Midbrain Dopaminergic Neurons.

SummaryHuman glial progenitor cells (hGPCs) are promising cellular substrates to explore for the in situ production of new neurons for brain repair. Proof of concept for direct neuronal reprogramming of glial progenitors has been obtained in mouse models in vivo, but conversion using human cells has not yet been demonstrated. Such studies have been difficult to perform since hGPCs are born late during human fetal development, with limited accessibility for in vitro culture. In this study, we show proof of concept of hGPC conversion using fetal cells and also establish a renewable and reproducible stem cell-based hGPC system for direct neural conversion in vitro. Using this system, we have identified optimal combinations of fate determinants for the efficient dopaminergic (DA) conversion of hGPCs, thereby yielding a therapeutically relevant cell type that selectively degenerates in Parkinson's disease. The induced DA neurons show a progressive, subtype-specific phenotypic maturation and acquire functional electrophysiological properties indicative of DA phenotype.

Therapeutic effects of intra-arterial administration of glial progenitor cells-conditioned medium in acute experimental ishemic stroke in rats

Transplantation of various types of stem cells as a possible therapy for stroke has been tested for years and the results are promising. Recently, most researchers are inclined to assume that the therapeutic effect of stem cell therapy is based on the mechanism of paracrine action associated with the secretion wide set of regulatory proteins. The aim of this study was to evaluate therapeutic effects of iPSC-derived glial progenitor cells conditioned medium in the rat middle cerebral artery occlusion model of the ischemic stroke. We showed that intra-arterial administration of glial progenitor cells conditioned medium promoted faster decrease of neurological deficit compared to the control group. Moreover, expression of gap43, bax, and tnfa genes involved in neuritogenesis, apoptosis and neuroinflammation was altered. However, no significant enhanced reduction of the infarct volume was registered. Our results demonstrated that administration of glial progenitor cells conditioned medium induced functional recovery after experimental stroke and may affect brain plasticity.

Inositol monophosphatase 1 (IMPA1) mutation in intellectual disability patients impairs neurogenesis but not gliogenesis.

A homozygous mutation in the inositol monophosphatase 1 (IMPA1) gene was recently identified in nine individuals with severe intellectual disability (ID) and disruptive behavior. These individuals belong to the same family from Northeastern Brazil, which has 28 consanguineous marriages and 59 genotyped family members. IMPA1 is responsible for the generation of free inositol from de novo biosynthesis and recycling from inositol polyphosphates and participates in the phosphatidylinositol signaling pathway. To understand the role of IMPA1 deficiency in ID, we generated induced pluripotent stem cells (iPSCs) from patients and neurotypical controls and differentiated these into hippocampal dentate gyrus-like neurons and astrocytes. IMPA1-deficient neuronal progenitor cells (NPCs) revealed substantial deficits in proliferation and neurogenic potential. At low passage NPCs (P1 to P3), we observed cell cycle arrest, apoptosis, progressive change to a glial morphology and reduction in neuronal differentiation. These observations were validated by rescuing the phenotype with myo-inositol supplemented media during differentiation of patient-derived iPSCs into neurons and by the reduction of neurogenic potential in control NPCs-expressing shIMPA1. Transcriptome analysis showed that NPCs and neurons derived from ID patients have extensive deregulation of gene expression affecting pathways necessary for neurogenesis and upregulation of gliogenic genes. IMPA1 deficiency did not affect cell cycle progression or survival in iPSCs and glial progenitor cells or astrocyte differentiation. Therefore, this study shows that the IMPA1 mutation specifically affects NPC survival and neuronal differentiation.

Therapeutic approach of stem cell transplantation for neonatal white matter injury

: The white matter in brain are mainly composed of oligodendrocytes and myelinated axons, and are important for the transmission of neural signals in central nervous system. White matter injury (WMI) is a leading cause of neurocognitive deficits in premature infants as the oligodendrocytes progenitors are easily attacked by hypoxia-ischemia (HI). Various clinical methods are used to treat this disease, while none of them could reverse the sequelae of WMI completely. With the development of stem cell technology, stem cell therapy has attracted huge interest as a novel treatment for WMI. A number of investigations have demonstrated the potential therapeutic effects of stem cell transplantation on WMI. Different types of stem cells have also been used by many researchers to test the therapeutic effect on WMI animal models, such as neural stem cells (NSCs), glial progenitor cells, mesenchymal stem cells (MSCs). In addition, some clinical trials have been conducted. Evidence suggests that transplantation of these stem cells into animals contributes to functional recovery after experimental WMI. The mechanisms of stem cells therapy may include differentiation into neurons and glial cells to replace lost cells, activation of endogenous NSC regeneration, and promotion of the release of neurotrophins. In this review, we summarized effects of different types of stem cells transplantation, the underlying mechanisms, the unsolved problems and concerns before clinical trials and transformation of stem cell therapy for WMI.

Human Progenitor Glial Cells Remyelinate Mice Models of MS, Resulting in Better Motor Function

Human Progenitor Glial Cells Remyelinate Mice Models of MS, Resulting in Better Motor Function

Abstract A35: From map to model: Genetic evolution of diffuse intrinsic pontine glioma provides the framework for accurate tumor modeling

Abstract Diffuse intrinsic pontine glioma (DIPG) is a devastating pediatric high-grade glioma (HGG) that diffusely penetrates the brainstem and is the leading cause of pediatric brain tumor death. Around 80% of DIPGs harbor lysine 27-methionine (K27M) substitutions in histone H3. H3K27M inhibits the activity of Polycomb repressive complex 2 (PRC2) that deposits H3K27me3, leading to widespread H3K27me3 loss, but how this leads to cancer is unclear. Further, despite clonal analysis indicating that H3K27M is the tumor-initiating mutation in DIPG, in vivo models of H3K27M-driven cancer have failed to generate tumors without additional oncogenic drivers. Thus, the early events driven by H3K27M alone remain obscure as does the most relevant cell of origin. To address the role of H3K27M in tumor initiation we generated a transgenic murine model with a tetracycline-repressible, Cre-inducible H3F3A-K27M transgene within the ROSA26 locus. This allows for both spatial and temporal control of K27M expression, via the cre-inducible LSL cassette and tetracycline treatment, respectively. These mice were crossed with the brain specific -cre drivers Nestin-, Olig2-, or GFAP-, targeting neural stem cells, oligodendrocyte progenitor cells, and glial progenitor cells, respectively. H3F3A K27M/-cre double-positive mice were born significantly below mendelian ratios, the most severe being those crossed with Olig2-cre (Nestin- 18/100; 0.18, GFAP- 15/114; 0.132, Olig2- 9/106; 0.08). All mice displayed a degree of ataxia and a smaller overall stature compared to littermate controls, with the most severe phenotype being particularly evident in Olig2-cre mice. Additionally, both Nestin- and GFAP-cre crosses experienced decreased survival post-weaning age (p21) (Nestin- 13/18 alive, GFAP- 10/15 alive); however, this decrease was greatly exaggerated in Olig2-cre (1/9 alive). Together, these data suggest that the displayed phenotypes are dependent upon the cell population in which H3F3A K27M is expressed. We also found that in addition to spatial control, temporal control of H3F3A K27M expression is critical to survival. Doxycycline (dox) was administered to breeding pairs for each H3F3A K27M/-cre line to repress transgene expression. Dox-H3F3A K27M/-cre double-positive mice were born at higher mendelian ratios than their no-dox counterparts (Nestin- 26/79; 0.33, GFAP- 14/50; 0.28, Olig2- 17/52; 0.327). Litters remained on dox treatment until either p0 or p21. Delayed H3F3A K27M expression led to an increase in overall survival in both treatment groups across all -cre lines, particularly Olig2-cre (Nestin- p0: 11/11, p21: 14/15, GFAP- p0: 4/4, p21: 9/10, Olig2- p0: 8/8, p21: 7/9), as well as an absence of ataxia and an increase in stature. This suggests that H3F3A K27M expression during a developmental window before p0 is critical to the onset of the observed phenotypes, in addition to the progenitor population being afflicted. Overall these data give insight into the spatial-temporal effects of H3K27M in early tumor development. Citation Format: Evan Lubanszky, Scott Ryall, Robert Siddaway, Byunjin Kim, Taylor Bridge, Sanja Pajovic, Cynthia Hawkins. From map to model: Genetic evolution of diffuse intrinsic pontine glioma provides the framework for accurate tumor modeling [abstract]. In: Proceedings of the AACR Special Conference on the Evolving Landscape of Cancer Modeling; 2020 Mar 2-5; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2020;80(11 Suppl):Abstract nr A35.

Identity and lineage fate of proteolipid protein 1 gene (Plp1)-expressing cells in the embryonic murine spinal cord.

The proteolipid protein (PLP) is the most abundant protein in the myelin sheath of the central nervous system (CNS). The gene coding PLP, proteolipid protein 1 (Plp1) is highly expressed in oligodendrocytes, the myelin-forming cells in the CNS. Previous studies demonstrate that Plp1 gene is expressed in the embryonic CNS much earlier before the generation of oligodendrocytes. However, the progenitor identity and the fate of Plp1-expressing cells are still elusive. We employed genetic approaches to permanently label Plp1-expressing cells with the reporter enhanced yellow fluorescence protein (EYFP) and used multicolored immunohistochemistry to characterize their identity and lineage fate. We found that Plp1-expressing cells were initially present without spatial restrictions and later confined to the ventral progenitor domains of the embryonic spinal cord. Our fate-mapping results showed that Plp1-expressing cells during early embryogenesis were multipotent neural progenitor cells that gave rise to not only neurons but also glial progenitor cells whereas they were bipotent glial progenitor cells during later neural development stages and generated oligodendroglial and astroglial lineage cells but not neurons. Intriguingly, postnatal astrocytes generated from embryonic Plp1-expressing glial progenitor cells were present only in the ventral spinal cord. Our study reveals that Plp1-expressing cells during embryonic neural development display dynamic cellular identities and have a broader lineage fate than oligodendroglial lineage.

Targeting Subventricular Zone Progenitor Cells with Intraventricular Liposomal Encapsulated Cytarabine in Patients with Secondary Glioblastoma : A Report of Two Cases.

Current treatments for glioblastoma (GB), the most common and malignant primary brain tumor are inadequate and as such, the median survival for most patients with GB is on the order of months, even after cytoreductive surgery, radiation and chemotherapy. Current study reports two cases of glioblastoma (GB) with subventricular zone (SVZ) involvement. SVZ biopsies demonstrated the presence of hypercellularity, nestin immunoreactivity, and a Ki-67 labeling index (LI) of 1-2%. Interestingly, tumor morphology and proliferative indices are different in the SVZ specimens than the hemispheric recurrences, which displayed similar nestin immunoreactivity, but a greater LI of 10%. Biopsy specimens demonstrated both intense nestin immunoreactivity and GFAP immunoreactivity in and around the GB recurrence. Nestin positive cells were more abundant closer to the SVZ nearest to the dorsolateral horn of the left lateral ventricle, while GFAP immunoreactivity was more intense closer to the center of the tumor recurrence. Additionally, co-labeling of cells with Ki67 and several different progenitor markers (CD133, CD140, TUJ-1, and nestin) demonstrated that these cells found in and around the GB recurrence were actively dividing. Having failed standard therapy with evidence of bi-hemispheric spread and progression to GB, we report a novel approach of using intraventricular liposomal encapsulated cytarabine (DepoCyt) for the treatment for GB by suppressing glial progenitor cells that surround the ventricular system in patients with GB. MRI and immunohistochemistry demonstrated that the SVZ is the incubator for future recurrences of GB and propose targeting SVZ progenitor cells with intraventricular liposomal encapsulated Ara-C. Two patients treated using this novel regimen have demonstrated partial radiographic responses warranting further studies looking at targeting the subventricular zone.

Embryonic microglia influence developing hypothalamic glial populations

BackgroundAlthough historically microglia were thought to be immature in the fetal brain, evidence of purposeful interactions between these immune cells and nearby neural progenitors is becoming established. Here, we examined the influence of embryonic microglia on gliogenesis within the developing tuberal hypothalamus, a region later important for energy balance, reproduction, and thermoregulation.MethodsWe used immunohistochemistry to quantify the location and numbers of glial cells in the embryonic brain (E13.5–E17.5), as well as a pharmacological approach (i.e., PLX5622) to knock down fetal microglia. We also conducted cytokine and chemokine analyses on embryonic brains in the presence or absence of microglia, and a neurosphere assay to test the effects of the altered cytokines on hypothalamic progenitor behaviors.ResultsWe identified a subpopulation of activated microglia that congregated adjacent to the third ventricle alongside embryonic Olig2+ neural progenitor cells (NPCs) that are destined to give rise to oligodendrocyte and astrocyte populations. In the absence of microglia, we observed an increase in Olig2+ glial progenitor cells that remained at the ventricle by E17.5 and a concomitant decrease of these Olig2+ cells in the mantle zone, indicative of a delay in migration of these precursor cells. A further examination of maturing oligodendrocytes in the hypothalamic grey and white matter area in the absence of microglia revealed migrating oligodendrocyte progenitor cells (OPCs) within the grey matter at E17.5, a time point when OPCs begin to slow their migration. Finally, quantification of cytokine and chemokine signaling in ex vivo E15.5 hypothalamic cultures +/− microglia revealed decreases in the protein levels of several cytokines in the absence of microglia. We assayed the influence of two downregulated cytokines (CCL2 and CXCL10) on neurosphere-forming capacity and lineage commitment of hypothalamic NPCs in culture and showed an increase in NPC proliferation as well as neuronal and oligodendrocyte differentiation.ConclusionThese data demonstrate that microglia influence gliogenesis in the developing tuberal hypothalamus.

Human Glial Progenitor Cells Effectively Remyelinate the Demyelinated Adult Brain

Neonatally transplanted human glial progenitor cells (hGPCs) can myelinate the brains of myelin-deficient shiverer mice, rescuing their phenotype and survival. Yet, it has been unclear whether implanted hGPCs are similarly able to remyelinate the diffusely demyelinated adult CNS. We, therefore, ask if hGPCs could remyelinate both congenitally hypomyelinated adult shiverers and normal adult mice after cuprizone demyelination. In adult shiverers, hGPCs broadly disperse and differentiate as myelinating oligodendrocytes after subcortical injection, improving both host callosal conduction and ambulation. Implanted hGPCs similarly remyelinate denuded axons after cuprizone demyelination, whether delivered before or after demyelination. RNA sequencing (RNA-seq) of hGPCs back from cuprizone-demyelinated brains reveals their transcriptional activation of oligodendrocyte differentiation programs, while distinguishing them from hGPCs not previously exposed to demyelination. These data indicate the ability of transplanted hGPCs to disperse throughout the adult CNS, to broadly myelinate regions of dysmyelination, and also to be recruited as myelinogenic oligodendrocytes later in life, upon demyelination-associated demand.

Centrosome anchoring regulates progenitor properties and cortical formation.

SUMMARYRadial glial progenitors (RGPs) represent the major neural progenitors for generating neurons and glia in the developing mammalian cerebral cortex 1-3. They position their centrosomes away from the nucleus at the ventricular zone surface 4-7. However, the molecular basis and precise function of this highly unique and characteristic subcellular organization of the centrosome remain largely unknown. Here we show that apical membrane anchoring of the centrosome controls the mechanical properties of mouse cortical RGPs and consequently their mitotic behaviour and cortical size and formation. Mother centriole in RGPs specifically develops distal appendages to anchor to the apical membrane. Selective removal of Centrosomal protein 83 (CEP83) eliminates mother centriole distal appendages and disrupts centrosome apical membrane anchorage, resulting in microtubule disorganization and apical membrane stretching and stiffening. It activates mechanically-sensitive Yes-associated protein (YAP) and promotes excessive RGP proliferation and subsequent intermediate progenitor overproduction, leading to the formation of an enlarged cortex with abnormal folding. Simultaneous elimination of YAP suppresses cortical enlargement and folding caused by CEP83 removal. Together, these results uncover a previously unknown role of the centrosome in regulating the mechanical features of neural progenitors, and the size and configuration of the mammalian cerebral cortex.

Imprinted Cdkn1c genomic locus cell-autonomously promotes cell survival in cerebral cortex development

The cyclin-dependent kinase inhibitor p57KIP2 is encoded by the imprinted Cdkn1c locus, exhibits maternal expression, and is essential for cerebral cortex development. How Cdkn1c regulates corticogenesis is however not clear. To this end we employ Mosaic Analysis with Double Markers (MADM) technology to genetically dissect Cdkn1c gene function in corticogenesis at single cell resolution. We find that the previously described growth-inhibitory Cdkn1c function is a non-cell-autonomous one, acting on the whole organism. In contrast we reveal a growth-promoting cell-autonomous Cdkn1c function which at the mechanistic level mediates radial glial progenitor cell and nascent projection neuron survival. Strikingly, the growth-promoting function of Cdkn1c is highly dosage sensitive but not subject to genomic imprinting. Collectively, our results suggest that the Cdkn1c locus regulates cortical development through distinct cell-autonomous and non-cell-autonomous mechanisms. More generally, our study highlights the importance to probe the relative contributions of cell intrinsic gene function and tissue-wide mechanisms to the overall phenotype.

TCTP is Essential for Cell Proliferation and Survival during CNS Development.

Translationally controlled tumor-associated protein (TCTP) has been implicated in cell growth, proliferation, and apoptosis through interacting proteins. Although TCTP is expressed abundantly in the mouse brain, little is known regarding its role in the neurogenesis of the nervous system. We used Nestin-cre-driven gene-mutated mice to investigate the function of TCTP in the nervous system. The mice carrying disrupted TCTP in neuronal and glial progenitor cells died at the perinatal stage. The NestinCre/+; TCTPf/f pups displayed reduced body size at postnatal day 0.5 (P0.5) and a lack of milk in the stomach compared with littermate controls. In addition to decreased cell proliferation, terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) and caspase assay revealed that apoptosis was increased in newly committed TCTP-disrupted cells as they migrated away from the ventricular zone. The mechanism may be that the phenotype from specific deletion of TCTP in neural progenitor cells is correlated with the decreased expression of cyclins D2, E2, Mcl-1, Bcl-xL, hax-1, and Octamer-binding transcription factor 4 (Oct4) in conditional knockout mice. Our results demonstrate that TCTP is a critical protein for cell survival during early neuronal and glial differentiation. Thus, enhanced neuronal loss and functional defect in Tuj1 and doublecortin-positive neurons mediated through increased apoptosis and decreased proliferation during central nervous system (CNS) development may contribute to the perinatal death of TCTP mutant mice.

Neural cells and their progenitors in regenerating zebrafish spinal cord.

The zebrafish (Danio rerio), among all amniotes is emerging as a powerful model to study vertebrate organogenesis and regeneration. In contrast to mammals, the adult zebrafish is capable of regenerating damaged axonal tracts; it can replace neurons and glia lost after spinal cord injury (SCI) and functionally recover. In the present paper, we report ultrastructural and cell biological analyses of regeneration processes after SCI. We have focused on event specific analyses of spinal cord regeneration involving different neuronal and glial cell progenitors, such as radial glia, oligodendrocyte progenitors (OPC), and Schwann cells. While comparing the different events, we frequently refer to previous ultrastructural analyses of central nervous system (CNS) injury in higher vertebrates. Our data show (a) the cellular events following injury, such as cell death and proliferation; (b) demyelination and remyelination followed by target innervation and regeneration of synaptic junctions and c) the existence of different progenitors and their roles during regeneration. The present ultrastructural analysis corroborates the cellular basis of regeneration in the zebrafish spinal cord and confirms the presence of both neuronal and different glial progenitors.

Comparative impact analysis of neuronal and glial progenitors conditioned medium on cerebellar neurons under glutamate exitotoxicity

One of the main causes of cell death in neurodegenerative diseases is excitotoxicity. Today the potential directions of treatment neurodegenerative diseases are including cell therapy, the purpose of which is to replace lost nerve tissue with donor cells. Transplanted cells along with replaced lost tissues have a paracrine effect, which requires careful study. The aim of this work was to study the effect of conditioned media, obtaining from neuronal and glial progenitor cells, on a primary culture of cerebellar neurons in a model of glutamate excitotoxicity. The cell viability, expression of marker genes for apoptosis and neuritogenesis, and the number of necrotic and apoptotic cells were determined in the culture of cerebellar neurons. The composition of the studied conditioned media was analyzed for the content of neurotrophins. A comparative analysis was revealed differences in the secretion of neurotrophins between the obtained cultures: the amount of brain-derived neurotrophic factor, nerve growth factor, ciliary neurotrophic factor and glial neurotrophic factor was higher in the secretion of glial progenitors. It was shown that the addition of conditioned media from neuronal cells does not significantly affect the viability of cerebellar neurons, whereas preincubation with media from glial progenitors has a neuroprotective effect by increasing the viability of cerebellar neurons, and during long-term cultivation promotes the growth of neurites by increasing the expression level of MAP2 and GAP43 genes.

Reconstruction of Cell-type-Specific Interactomes at Single-Cell Resolution.

The human interactome is instrumental in the systems-level study of the cell and the contextualization of disease-associated gene perturbations. However, reference organismal interactomes do not capture the cell-type-specific context in which proteins and modules preferentially act. Here, we introduce SCINET, a computational framework that reconstructs an ensemble of cell-type-specific interactomes by integrating a global, context-independent reference interactome with a single-cell gene-expression profile. SCINET addresses technical challenges of single-cell data by robustly imputing, transforming, and normalizing the initially noisy and sparse expression of data. Inferred cell-level gene interaction probabilities and group-level interaction strengths define cell-type-specific interactomes. We use SCINET to reconstruct and analyze interactomes of the major human brain and immune cell types, revealing specificity and modularity of perturbations associated with neurodegenerative, neuropsychiatric, and autoimmune disorders. We report cell-type interactomes for brain and immune cell types, together with the SCINET package.

GENE-08. SECONDARY GLIOBLASTOMA, IDH-WILDTYPE ARISING IN DIFFUSE ASTROCYTOMA, IDH-MUTANT: A CASE REPORT

Abstract Primary glioblastoma develops de novo without clinical or histological evidence of a low-grade precursor lesion, while secondary glioblastoma develops from a low-grade glioma. The same IDH mutation is observed in almost secondary glioblastomas that occurs in low-grade gliomas with IDH mutation. Present report is an extraordinary case of secondary glioblastoma, IDH-wildtype arising in diffuse astrocytoma, IDH-mutant. A 31-year-old female presented with seizure 3 months ago, who had a history of operation for diffuse astrocytoma, IDH-mutant on the left frontal lobe 6 years ago. Magnetic resonance imaging test revealed new infiltrative lesions (6.5cm) in left frontal lobe and corpus callosum, in addition to the non-enhancing mass (3.4cm). New infiltrative lesion suspected anaplastic change and the patient underwent tumorectomy. Microscopically, non-enhancing lesion showed high cellularity, moderate nuclear atypia and brisk mitosis. Microvascular proliferation and necrosis were absent that can be diagnosis as anaplastic astrocytoma. However, new infiltrative lesion showed microvascular proliferation and necrosis that acceptable for diagnosis as glioblastoma. IDH-1 immunohistochemistry (IHC) was positive in anaplastic astrocytoma but negative in glioblastoma. In addition, we assessed NGS based on the SNUBH Brain v1.0 (Macrogen, Seoul, South Korea) panel. Similar to IHC result, IDH-1 (p.Arg132His) mutation was found in anaplastic astrocytoma but not in glioblastoma. Interestingly, ATRX (p.Gln1670Ter) and TP53 (p.His193Arg) mutations were found in both lesions. Additionally, PTEN (p.His296Pro) mutation was identified in glioblastoma component only. Until now, it is well-known hypothesis that the IDH mutation initiated in glial progenitor cell and the other genetic mutations occur sequentially in pathogenesis of secondary glioblastoma. Notably, this is the first case report that other genetic alterations can be initiated before IDH mutation contrary to previous hypothesis. In our case, mutation of ATRX and TP53 might be initiated, and PTEN and IDH-1 mutations were sequentially occurred in glioblastoma and anaplastic astrocytoma, respectively.