Glial Precursor Cells Research Articles

Autologous Transplantation of Skin-Derived Precursor Cells in a Porcine Model

BackgroundHirschprung's disease is characterized by aganglionic bowel and often requires surgical resection. Cell-based therapies have been investigated as potential alternatives to restore functioning neurons. Skin-derived precursor cells (SKPs) differentiate into neural and glial cells in vitro and generate ganglion-like structures in rodents. In this report, we aimed to translate this approach into a large animal model of aganglionosis using autologous transplantation of SKPs. MethodsJuvenile pigs underwent skin procurement from the shoulder and simultaneous chemical denervation of an isolated colonic segment. Skin cells were cultured in neuroglial-selective medium and labeled with fluorescent dye for later identification. The cultured SKPs were then injected into the aganglionic segments of colon, and the specimens were retrieved within seven days after transplantation. SKPs in vitro and in vivo were assessed with histologic samples for various immunofluorescent markers of multipotency and differentiation. SKPs from the time of harvest were compared to those at the time of injection using PCR. ResultsPrior to transplantation, 72% of SKPs stained positive for nestin and S100b, markers of neural and glial precursor cells of neural crest origin, respectively. Markers of differentiated neurons and gliocytes, TUJ1 and GFAP, were detected in 47% of cultured SKPs. After transplantation, SKPs were identified in both myenteric and submucosal plexuses of the treated colon. Nestin co-expression was detected in the SKPs within the aganglionic colon in vivo. Injected SKPs appeared to migrate and express early neuroglial differentiation markers. ConclusionsAutologous SKPs implanted into aganglionic bowel demonstrated immunophenotypes of neuroglial progenitors. Our results suggest that autologous SKPs may be potentially useful for cell-based therapy for patients with enteric nervous system disorders. Type of StudyBasic science.

Translating neural stem cells to neurons in the mammalian brain.

The mammalian neocortex underlies our perception of sensory information, performance of motor activities, and higher-order cognition. During mammalian embryogenesis, radial glial precursor cells sequentially give rise to diverse populations of excitatory cortical neurons, followed by astrocytes and oligodendrocytes. A subpopulation of these embryonic neural precursors persists into adulthood as neural stem cells, which give rise to inhibitory interneurons and glia. Although the intrinsic mechanisms instructing the genesis of these distinct progeny have been well-studied, most work to date has focused on transcriptional, epigenetic, and cell-cycle control. Recent studies, however, have shown that posttranscriptional mechanisms also regulate the cell fate choices of transcriptionally primed neural precursors during cortical development. These mechanisms are mediated primarily by RNA-binding proteins and microRNAs that coordinately regulate mRNA translation, stability, splicing, and localization. Together, these findings point to an extensive network of posttranscriptional control and provide insight into both normal cortical development and disease. They also add another layer of complexity to brain development and raise important biological questions for future investigation.

Dendropanax morbiferus leaf extract facilitates oligodendrocyte development.

Treatment of multiple sclerosis is effective when anti-inflammatory, neuroprotective and regenerative strategies are combined. Dendropanax morbiferus (DM) has anti-inflammatory, anti-oxidative properties, which may be beneficial for multiple sclerosis. However, there have been no reports on the effects of DM on myelination, which is critical for regenerative processes. To know whether DM benefits myelination, we checked differentiation and myelination of oligodendrocytes (OLs) in various primary culture systems treated with DM leaf EtOH extracts or control. DM extracts increased the OL membrane size in the mixed glial and pure OL precursor cell (OPC) cultures and changed OL-lineage gene expression patterns in the OPC cultures. Western blot analysis of DM-treated OPC cultures showed upregulation of MBP and phosphorylation of ERK1/2. In myelinating cocultures, DM extracts enhanced OL differentiation, followed by increased axonal contacts and myelin gene upregulations such as Myrf, CNP and PLP. Phytochemical analysis by LC-MS/MS identified multiple components from DM extracts, containing bioactive molecules such as quercetin, cannabidiol, etc. Our results suggest DM extracts enhance OL differentiation, followed by an increase in membrane size and axonal contacts, thereby indicating enhanced myelination. In addition, we found that DM extracts contain multiple bioactive components, warranting further studies in relation to finding effective components for enhancing myelination.

Patient with Refractory Epilepsy Associated with Oligondendroglioma

Oligodendroglioma is a rare form of primary brain tumor, accounting for about 2-5% of intracranial tumors, being more common in adult males but rare in children, accounting for about 1-2% of all primary brain tumors in children. It originates from oligodendrocytes or glial precursor cells and exhibits infiltrative and slow growth. They can be classified in two grades (Grade II and Grade III), where Grade II are low grade tumors and have tumor cells that grow slowly and invade nearby normal tissue, and Grade III are malignant and have rapidly growing tumors. It has low growth and 50-80% of cases first symptom is seizures. A seizure is a symptom that requires a rapid solution usually requiring empirical treatment at the initial time to cease seizures and promote some well-being for the patient's routine. Seizures can cause a lot of damage to the patient's life, especially if the patient is a child who does not know what to do and what to do. Depending on the intensity and frequency of seizure episodes, the patient may experience fractures with falls, may suffer discrimination and prejudice at school. The causes behind refractory epilepsy are diverse, so whenever a patient is found to be refractory to drug treatment, the origin of seizures should be investigated early, it is not enough to stop at empirical treatment.

Pparα deficiency inhibits the proliferation of neuronal and glial precursors in the zebrafish central nervous system.

Many molecules and signaling pathways involved in neural development play a role in neurodegenerative diseases and brain tumor progression. Peroxisome proliferator-activated receptor (PPAR) proteins regulate the differentiation of tissues and the progression of many diseases. However, the role of these proteins in neural development is unclear. We examined the function of Pparα in the neural development of zebrafish. Two duplicate paralogs for mammalian PPARA/Ppara, namely pparaa and pparab, are present in the zebrafish genome. Both pparaa and pparab are expressed in the developing central nervous system in zebrafish embryos. Inhibiting the function of Pparα by using either the PPARα/Pparα antagonist GW6471 or pparaa or pparab truncated constructs produced identical phenotypes, which were sufficient to reduce the proliferation of neuronal and glial precursor cells without affecting the formation of neural progenitors. We demonstrated that both Pparαa and Pparαb proteins are essential regulators of the proliferation of neuronal and glial precursors. This study provides a better understanding of the functions of PPARα/Pparα in neural development and further expands our knowledge of the potential role of PPARα/Pparα in neurological disorders and brain tumors. Developmental Dynamics 247:1264-1275, 2018. © 2018 Wiley Periodicals, Inc.

Malignant gliomas can be converted to non‑proliferating glial cells by treatment with a combination of small molecules.

Gliomas, the most highly malignant central nervous system tumors, are associated with an extremely poor patient survival rate. Given that gliomas are derived from mutations in glial precursor cells, a considerable number of them strongly react with glial precursor cell‑specific markers. Thus, we investigated whether malignant gliomas can be converted to glial cells through the regulation of endogenous gene expression implicated in glial precursor cells. In the present study, we used three small‑molecule compounds, [cyclic adenosine monophosphate (cAMP) enhancer, a mammalian target of rapamycin (mTOR) inhibitor, and a bromodomain and extra‑terminal motif (BET) inhibitor] for glial reprogramming. Small‑molecule‑induced gliomas (SMiGs) were not only transformed into exhibiting a glial‑specific morphology, but also showed positive reactions with glial‑specific markers such as glial fibrillary acidic protein (GFAP), 2',3'‑cyclic nucleotide3'‑phosphohydrolase (CNP) and anti‑oligodendrocyte (RIP). A microarray analysis indicated that SMiGs exhibited a marked increase in specific gene levels, whereas that of a malignant cancer‑specific gene was greatly decreased. Moreover, proliferation of the cells was markedly suppressed after the conversion of malignant glioma cells into glial cells. Our findings confirmed that malignant gliomas can be reprogrammed to non‑proliferating glial cells, using a combination of small molecules, and their proliferation can be regulated by their differentiation. We suggest that our small‑molecule combination (with forskolin, rapamycin and I‑BET151) may be the next generation of anticancer agents that act by reprogramming malignant gliomas to differentiate into glial cells.

Sequentially acting SOX proteins orchestrate astrocyte- and oligodendrocyte-specific gene expression.

SOX transcription factors have important roles during astrocyte and oligodendrocyte development, but how glial genes are specified and activated in a sub-lineage-specific fashion remains unknown. Here, we define glial-specific gene expression in the developing spinal cord using single-cell RNA-sequencing. Moreover, by ChIP-seq analyses we show that these glial gene sets are extensively preselected already in multipotent neural precursor cells through prebinding by SOX3. In the subsequent lineage-restricted glial precursor cells, astrocyte genes become additionally targeted by SOX9 at DNA regions strongly enriched for Nfi binding motifs. Oligodendrocyte genes instead are prebound by SOX9 only, at sites which during oligodendrocyte maturation are targeted by SOX10. Interestingly, reporter gene assays and functional studies in the spinal cord reveal that SOX3 binding represses the synergistic activation of astrocyte genes by SOX9 and NFIA, whereas oligodendrocyte genes are activated in a combinatorial manner by SOX9 and SOX10. These genome-wide studies demonstrate how sequentially expressed SOX proteins act on lineage-specific regulatory DNA elements to coordinate glial gene expression both in a temporal and in a sub-lineage-specific fashion.

Early Postnatal Valproic Acid Exposure Increase the Protein Level of Astrocyte Markers in Frontal Cortex of Rat.

ObjectiveIn our previous study, it has been reported that valproic acid (VPA) effects gliogenesis and increases the number of glial precursor cells during the early postnatal period. However there is no specific report that whether this process is going on up to the age of mature brain development and the consequence effect of this ongoing gliogenesis process.MethodsAs an ongoing study, using Immunoblotting analysis, we checked the level of glial protein and glial-derived factor markers in the frontal cortex of a rat brain at postnatal day (PND) 21.ResultsThe finding of the study suggests that, in the VPA group (p<0.05), early exposure elicited significantly to increase the expression level of glial protein cells at PND 21 in the frontal cortex of rat brain.ConclusionTherefore we suggest that, alter gliogenesis and abnormal number of glial cells modulate the neurobiological dysfunction and induces the risk of neurodevelopmental disorders.

IDH2 mutations are commonly associated with 1p/19q codeletion in diffuse adult gliomas.

716 IDH2 mutations are commonly associated with 1p/19q codeletion in diffuse adult gliomas Diffuse gliomas are classified according to the 2016 World Health Organization (WHO) Classification of Tumors of the Central Nervous System, 1 which combines histological and molecular features. Diagnosis requires the assessment of mutations in the isocitrate dehydrogenase genes (IDH1 and IDH2), key genetic alterations characterizing gliomas with favorable outcome. 2 Because IDH1 and IDH2 are highly similar enzymes, the WHO classification, as most of the current studies, combines these mutations into the same molecular group; however, it is unclear whether these tumors share the same characteristics. We analyzed data from 1517 patients included in the French POLA Network to investigate differences between IDH1-and IDH2-mutant gliomas. Inclusion criteria were the written consent of the patient for clinical data collection and genetic analysis and sufficient material for molecular studies allowing classification according to the 2016 WHO classification. IDH1-R132H mutational status was evaluated using automated immunohistochemistry in all cases (n = 1517). Direct sequencing 3 was performed in 978 cases and demonstrated IDH mutation in 573 cases (this includes confirmation of IDH1-R132H mutation in 468 cases, other IDH1 mutations in 61 cases, and IDH2 mutation in 44 cases). The 1p/19q codeletion status was determined based on single nucleotide polymor-phism arrays, comparative genomic hybridization arrays, and/ or microsatellite marker analysis. 3 The following data were recorded: age, sex, follow-up, and MRI features (tumor location , extension, contrast enhancement, edema). All statistical analysis was done using IBM SPSS statistics software version 23. Chi-square test was used to compare qualitative variables. Continuous variables were compared using the Mann– Whitney U-test, and the Kaplan–Meier method was used to estimate survival distributions. Among the 1517 patients, 1025 had an IDH-mutant tumor: 96% were IDH1-mutant and 4% IDH2-mutant. Integrated diagnoses are summarized in Fig. 1. The frequency of 1p/19q code-letion was higher in the IDH2-mutant group compared with the IDH1-mutant group (91% vs 48%, P < 0.001). Wang and coworkers previously reported higher frequency of 1p/19q codeletion in IDH2-mutant gliomas (9/18 samples) compared with IDH1-mutant. 4 The percentage of each category in our study does not reflect the normal distribution of glioma because of the inclusion criteria in the POLA Network (ie, high-grade glioma with oligodendroglial component). However, the higher proportion of 1p/19q codeleted glioma in the IDH2-mutant group cannot be attributed to the inclusion criteria. Because the main population of glioma associated with IDH2 mutation was 1p/19q codeleted anaplastic oligodendroglioma, we focused on this subgroup to search for differences compared with IDH1 mutation. Among these patients (n = 474), we did not observe any difference in terms of age, sex, progression free survival, or overall survival between IDH1-and IDH2-mutant tumors. However, IDH2-mutant anaplastic oli-godendrogliomas presented more frequently with multilobar extension (56% of the IDH2-mutant vs 35% of the IDH1-mutant, P = 0.015) and edema (79% vs 57%, P = 0.02). Furthermore, bifrontal location with corpus callosum involvement was more frequent in IDH2-mutant compared with IDH1-mutant tumors (41% vs 16%, P < 0.001). IDH mutation is supposed to be one of the first hits of gliomagenesis, 5 resulting in production of an oncome-tabolite, D-2-hydroxyglutarate (D-2HG), which impacts the α-ketoglutarate–dependent dioxygenase functions. Previous studies demonstrated that the potential for IDH-mutant enzymes to produce D-2HG depends on the mutation type. 6 Based on our observations, we could hypothesize that the higher D-2HG accumulation induced by IDH2 mutation may lead to a phenotype that is favorable to 1p/19q chromosomal loss. It may also impact distinct cellular pathways that promote a more invasive phenotype. Whether IDH1 or IDH2 mutations impact distinct glial precursor cells with differential invasive properties remains to be elucidated. In conclusion, our results illustrate that IDH2-mutant glio-mas are commonly associated with 1p/19q codeletion. Most of IDH2-mutant anaplastic oligodendroglioma 1p/19q codeleted are multilobar. Understanding the genomic events involved in these specificities may represent a step forward for therapeutic development.

New aspects of glioblastoma multiforme revealed by similarities between neural and glioblastoma stem cells.

Neural stem cells (NSCs) undergo self-renewal and generate neurons and glial cells under the influence of specific signals from surrounding environments. Glioblastoma multiforme (GBM) is a highly lethal brain tumor arising from NSCs or glial precursor cells owing to dysregulation of transcriptional and epigenetic networks that control self-renewal and differentiation of NSCs. Highly tumorigenic glioblastoma stem cells (GSCs) constitute a small subpopulation of GBM cells, which share several characteristic similarities with NSCs. GSCs exist atop a stem cell hierarchy and generate heterogeneous populations that participate in tumor propagation, drug resistance, and relapse. During multimodal treatment, GSCs de-differentiate and convert into cells with malignant characteristics, and thus play critical roles in tumor propagation. In contrast, differentiation therapy that induces GBM cells or GSCs to differentiate into a neuronal or glial lineage is expected to inhibit their proliferation. Since stem cell differentiation is specified by the cells' epigenetic status, understanding their stemness and the epigenomic situation in the ancestor, NSCs, is important and expected to be helpful for developing treatment modalities for GBM. Here, we review the current findings regarding the epigenetic regulatory mechanisms of NSC fate in the developing brain, as well as those of GBM and GSCs. Furthermore, considering the similarities between NSCs and GSCs, we also discuss potential new strategies for GBM treatment.

MicroRNA-219 Reduces Viral Load and Pathologic Changes in Theiler's Virus-Induced Demyelinating Disease.

Analysis of microRNA (miR) expression in the central nervous system white matter of SJL mice infected with the BeAn strain of Theiler's murine encephalomyelitis virus (TMEV) revealed a significant reduction of miR-219, a critical regulator of myelin assembly and repair. Restoration of miR-219 expression by intranasal administration of a synthetic miR-219 mimic before disease onset ameliorates clinical disease, reduces neurogliosis, and partially recovers motor and sensorimotor function by negatively regulating proinflammatory cytokines and virus RNA replication. Moreover, RNA sequencing of host lesions showed that miR-219 significantly downregulated two genes essential for the biosynthetic cholesterol pathway, Cyp51 (lanosterol 14-α-demethylase) and Srebf1 (sterol regulatory element-binding protein-1), and reduced cholesterol biosynthesis in infected mice and rat CG-4 glial precursor cells in culture. The change in cholesterol biosynthesis had both anti-inflammatoryand anti-viral effects. Because RNA viruses hijack endoplasmic reticulum double-layered membranes to provide a platform for RNA virus replication and are dependent on endogenous pools of cholesterol, miR-219 interference with cholesterol biosynthesis interfered virus RNA replication. These findings demonstrate that miR-219 inhibits TMEV-induced demyelinating disease through its anti-inflammatory and anti-viral properties.

Glial cell responses in a murine multifactorial perinatal brain injury model

The impact of traumatic brain injury during the perinatal period, which coincides with glial cell (astrocyte and oligodendrocyte) maturation was assessed to determine whether a second insult, e.g., increased inflammation due to remote bacterial exposure, exacerbates the initial injury’s effects, possibly eliciting longer-term brain damage. Thus, a murine multifactorial injury model incorporating both mechanisms consisting of perinatal penetrating traumatic brain injury, with or without intraperitoneal injection of lipopolysaccharide (LPS), an analog of remote pathogen exposure has been developed. Four days after injury, gene expression changes for different cell markers were assessed using mRNA in situ hybridization (ISH) and qPCR. Astrocytic marker mRNA levels increased in the stab-alone and stab-plus-LPS treated animals indicating reactive gliosis. Activated microglial/macrophage marker levels, increased in the ipsilateral sides of stab and stab-plus LPS animals by P10, but the differences resolved by P15. Ectopic expression of glial precursor and neural stem cell markers within the cortical injury site was observed by ISH, suggesting that existing precursors and neural stem cells migrate into the injured areas to replace the cells lost in the injury process. Furthermore, single exposure to LPS concomitant with acute stab injury affected the oligodendrocyte population in both the injured and contralateral uninjured side, indicating that after compromise of the blood-brain barrier integrity, oligodendrocytes become even more susceptible to inflammatory injury. This multifactorial approach should lead to a better understanding of the pathogenic sequelae observed as a consequence of perinatal brain insult/injury, caused by combinations of trauma, intrauterine infection, hypoxia and/or ischemia in humans.

EGF Enhances Oligodendrogenesis from Glial Progenitor Cells.

Emerging evidence indicates that epidermal growth factor (EGF) signaling plays a positive role in myelin development and repair, but little is known about its biological effects on the early generation and differentiation of oligodendrocyte (OL) lineage cells. In this study, we investigated the role of EGF in early OL development with isolated glial restricted precursor (GRP) cells. It was found that EGF collaborated with Platelet Derived Growth Factor-AA (PDGFaa) to promote the survival and self-renewal of GRP cells, but predisposed GRP cells to develop into O4− early-stage oligodendrocyte precursor cells (OPCs) in the absence of or PDGFaa. In OPCs, EGF synergized with PDGFaa to maintain their O4 negative antigenic phenotype. Upon PDGFaa withdrawal, EGF promoted the terminal differentiation of OPCs by reducing apoptosis and increasing the number of mature OLs. Together, these data revealed that EGF is an important mitogen to enhance oligodendroglial development.

A giant solid cystic inferior fourth ventricle subependymoma – Case report and literature review

Abstract Subependymomas are a rare subtype of ependymomas, slow growing WHO grade I tumors that develop either intracranial from the subependymal glial precursor cells layer of the ventricles or intramedullary. These tumors originate in the undifferentiated Subependymal layer of cells that can become either ependymocytes or astrocytes. Most of the subependymomas are located inside the fourth ventricle (50-60%). We reviewed the case of a 40 years old woman with a giant solid cystic fourth ventricle ependymoma. The patient underwent total resection of the tumor through a subociipital transvermian approach. We discussed the characteristics of these benign tumors and reviewed the literature on this subject and concluded that total resection is the treatment of choice for symptomatic Subependymomas localized in posterior fossa.

Immune infiltration, glioma stratification, and therapeutic implications

By definition, gliomas are brain tumors emanating from glial precursor cells. Gliomas include glioblastoma (GBM), astrocytoma, oligodendroglioma, and ependymoma. The World Health Organization (WHO) traditionally classifies brain tumors according to their pathological features, with GBM having the highest grade (IV), while lower grades (mostly II, III) are typically assigned to various types of astrocytic, oligodendroglial, and ependymal tumors (1), which collectively are referred to as lower grade gliomas (LGG). In the latest NCI SEER (Surveillance, Epidemiology, and End Results) report and projection, the estimated 2016 incidence and deaths for brain and other CNS tumors is 23,770 and 16,050, respectively (2). According to CBTRUS (Central Brain Tumor Registry of the United States), glioma represents about 27% of all, and 80% of malignant brain and CNS tumors (3). The majority (55.1%) of gliomas are classified as GBMs. For GBMs, the current standard of care consists of surgical resection, radiotherapy with chemotherapy (temozolomide or TMZ). The median survival rate, which ranges from 14.5 to 16.6 months [see (4,5) for review], remains dismally poor despite decades of research and discoveries, leading up to the current era of genomics, targeted therapeutics, and immunotherapeutics. LGGs on the other hand have more favorable clinical outcome, especially cases possessing IDH mutation and co-deletion of 1p and 19q chromosomal arms.

Down-Regulated Expression of Liver X Receptor beta in Cortical Lesions of Patients with Focal Cortical Dysplasia.

Focal cortical dysplasia (FCD) is strongly associated with medically intractable epilepsy. Studies suggest that liver X receptor beta (LXRβ) may participate in the pathogenesis of FCD. The present study investigated the expression pattern of LXRβ in FCD and the distribution of LXRβ in different neural precursor cells. Twenty-five surgical specimens from FCD patients and 11 age-matched control samples from autopsies were included in our study. Protein levels and distribution were detected by western blot, immunohistochemistry, and immunofluorescence staining. We found that (1) the level of LXRβ protein was markedly reduced in FCD. (2) LXRβ staining was weaker in the dysplastic cortices of FCD and was mainly observed in neuronal microcolumns, and malformed cells. (3) LXRβ was co-localized with radial glial cells (RGCs) markers and oligodendrocyte precursor cells (OPCs) markers in malformed cells. (4) RGCs marker and OPCs marker were down-regulated while LXRβ downstream factors were up-regulated in FCD specimens. Taken together, our results indicate that LXRβ may interact with β-catenin to regulate the generation of OPCs and the transformation of RGCs. LXRβ therefore potentially contributes to the pathogenesis of FCD.

Wnt Signaling Specifies Anteroposterior Progenitor Zone Identity in the Drosophila Visual Center.

During brain development, various types of neuronal populations are produced from different progenitor pools to produce neuronal diversity that is sufficient to establish functional neuronal circuits. However, the molecular mechanisms that specify the identity of each progenitor pool remain obscure. Here, we show that Wnt signaling is essential for the specification of the identity of posterior progenitor pools in the Drosophila visual center. In the medulla, the largest component of the visual center, different types of neurons are produced from two progenitor pools: the outer proliferation center (OPC) and glial precursor cells (GPCs; also known as tips of the OPC). We found that OPC-type neurons are produced from the GPCs at the expense of GPC-type neurons when Wnt signaling is suppressed in the GPCs. In contrast, GPC-type neurons are ectopically induced when Wnt signaling is ectopically activated in the OPC. These results suggest that Wnt signaling is necessary and sufficient for the specification of the progenitor pool identity. We also found that Homothorax (Hth), which is temporally expressed in the OPC, is ectopically induced in the GPCs by suppression of Wnt signaling and that ectopic induction of Hth phenocopies the suppression of Wnt signaling in the GPCs. Thus, Wnt signaling is involved in regionalization of the fly visual center through the specification of the progenitor pool located posterior to the medulla by suppressing Hth expression. Brain consists of considerably diverse neurons of different origins. In mammalian brain, excitatory and inhibitory neurons derive from the dorsal and ventral telencephalon, respectively. Multiple progenitor pools also contribute to the neuronal diversity in fly brain. However, it has been unclear how differences between these progenitor pools are established. Here, we show that Wnt signaling, an evolutionarily conserved signaling, is involved in the process that establishes the differences between these progenitor pools. Because β-catenin signaling, which is under the control of Wnt ligands, specifies progenitor pool identity in the developing mammalian thalamus, Wnt signaling-mediated specification of progenitor pool identity may be conserved in insect and mammalian brains.

Inhibition of Epidermal Growth Factor Receptor Improves Myelination and Attenuates Tissue Damage of Spinal Cord Injury.

Preventing demyelination and promoting remyelination of denuded axons are promising therapeutic strategies for spinal cord injury (SCI). Epidermal growth factor receptor (EGFR) inhibition was reported to benefit the neural functional recovery and the axon regeneration after SCI. However, its role in de- and remyelination of axons in injured spinal cord is unclear. In the present study, we evaluated the effects of EGFR inhibitor, PD168393 (PD), on the myelination in mouse contusive SCI model. We found that expression of myelin basic protein (MBP) in the injured spinal cords of PD treated mice was remarkably elevated. The density of glial precursor cells and oligodendrocytes (OLs) was increased and the cell apoptosis in lesions was attenuated after PD168393 treatment. Moreover, PD168393 treatment reduced both the numbers of OX42+microglial cells and glial fibrillary acidic protein+astrocytes in damaged area of spinal cords. We thus conclude that the therapeutic effects of EGFR inhibition after SCI involves facilitating remyelination of the injured spinal cord, increasing of oligodendrocyte precursor cells and OLs, as well as suppressing the activation of astrocytes and microglia/macrophages.

Glial progenitor cell migration promotes CNS axon growth on functionalized electroconducting microfibers

Electroactive systems that promote directional axonal growth and migration of glial progenitor cells (GPC) are needed for the treatment of neurological injuries. We report the functionalization of electroconducting microfibers with multiple biomolecules that synergistically stimulate the proliferation and migration of GPC, which in turn induce axonal elongation from embryonic cerebral cortex neurons. PEDOT doped with poly[(4-styrenesulfonic acid)-co-(maleic acid)] was synthesized on carbon microfibers and used for covalent attachment of molecules to the electroactive surface. The molecular complexes that promoted GPC proliferation and migration, followed by axonal extension, were composed of polylysine, heparin, basic fibroblast growth factor (bFGF), and matricellular proteins; the combination of bFGF with vitronectin or fibronectin being indispensable for sustained glial and axonal growth. The rate of glial-induced axonal elongation was about threefold that of axons growing directly on microfibers functionalized with polylysine alone. Electrical stimuli applied through the microfibers released bFGF and fibronectin from the polymer surface, consequently reducing GPC proliferation and promoting their differentiation into astrocytes, without causing cell detachment or toxicity. These results suggest that functionalized electroactive microfibers may provide a multifunctional tool for controlling neuron-glia interactions and enhancing neural repair. Statement of SignificanceWe report a multiple surface functionalization strategy for electroconducting microfibers (MFs), in order to promote proliferation and guided migration of glial precursor cells (GPC) and consequently create a permissive substrate for elongation of central nervous system (CNS) axons. GPC divided and migrated extensively on the functionalized MFs, leading to fast elongation of embryonic cerebral cortex axons. The application of electric pulses thorough the MFs controlled glial cell division and differentiation. The functionalized MFs provide an advanced tool for neural tissue engineering and for controlling neuron-glial interactions. CNS axonal growth associated to migratory glial precursors, together with the possibility of directing glial differentiation by electrical stimuli applied through the MFs, open a new research avenue to explore for CNS repair.

Abstract B01: Biological consequences of histone mutations in the mammalian brain

Abstract Pediatric high-grade gliomas (HGGs) are devastating diseases with poor prognosis. The two-year survival for pediatric HGG ranges from 30%, for tumors arising in the cerebral cortex, to less than 10% for diffuse intrinsic pontine gliomas (DIPGs), which arise in the brainstem. Recurrent somatic mutations in histone H3 found in pediatric HGGs are rare in adult HGGs and may represent genetic drivers of disease. Mutually exclusive somatic heterozygous H3F3A or HIST1H3B mutations encoding a K27M variant of histone H3.3 or H3.1, respectively, are found in nearly 80 percent of DIPGs and 22 percent of non-brainstem HGG, where they occur predominantly in thalamic and other midline tumors. Strikingly, heterozygous H3F3A mutations encoding histone H3.3 G34R or G34V occur in approximately 14 percent of non-brainstem HGG, and are associated predominantly with cortical tumors arising in older children through young adulthood, suggesting a distinct developmental origin compared to the majority of tumors harboring K27M mutations. DNA methylation signatures and gene expression patterns distinguish G34R/V and K27M tumors, but the oncogenic mechanisms and brain region selectivity of these mutations are still uncertain. To study these mutations in the developing mammalian brain, we generated conditionally activated, epitope tagged H3f3a knock-in mice to express K27M, G34R or non-mutated H3.3 proteins. When activated in neural and glial precursor cells, extensive H3f3a expression was observed throughout the embryonic brain, and H3.3-K27M induced loss of H3K27me3, consistent with observations in K27M mutant DIPG tumor samples. Moreover, neural stem cells expressing H3.3-K27M demonstrated an in vitro growth advantage compared to H3.3-G34R or H3.3-WT expressing neural stem cells. We will present an analysis of the epigenetic landscape and gene expression signatures associated with the histone H3 K27M and G34R mutations in different brain regions as well as phenotypic analysis of the mutant mice. Citation Format: Jon D. Larson, Lawryn H. Kasper, Helen R. Russell, Chunxu Qu, Xiaoyan Zhu, Peter J. McKinnon, Suzanne J. Baker. Biological consequences of histone mutations in the mammalian brain. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Sep 24-27, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2016;76(2 Suppl):Abstract nr B01.