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Dynamic alterations in the unique brain extracellular matrix (ECM) are involved in malignant brain tumors. Yet studies of brain ECM roles in tumor cell behavior have been difficult due to lack of access to the human brain. We present a tunable 3D bioengineered brain tissue platform by integrating microenvironmental cues of native brain-derived ECMs and live imaging to systematically evaluate patient-derived brain tumor responses. Using pediatric ependymoma and adult glioblastoma as examples, the 3D brain ECM-containing microenvironment with a balance of cell-cell and cell-matrix interactions supports distinctive phenotypes associated with tumor type-specific and ECM-dependent patterns in the tumor cells’ transcriptomic and release profiles. Label-free metabolic imaging of the composite model structure identifies metabolically distinct sub-populations within a tumor type and captures extracellular lipid-containing droplets with potential implications in drug response. The versatile bioengineered 3D tumor tissue system sets the stage for mechanistic studies deciphering microenvironmental role in brain tumor progression., The brain extracellular matrix (ECM) is altered in brain tumors, but its role in cancer progression and drug sensitivity are difficult to study. Here the authors develop a 3D bioengineered brain tissue model using patient-derived samples and tunable brain-derived ECM to examine the interplay between cells and the ECM.

Adult human neural progenitor and stem cells have been implicated as a potential source of brain cancer causing cells, but specific events that might cause cells to progress towards a transformed phenotype remain unclear. The L1CAM (L1) cell adhesion/recognition molecule is expressed abnormally by human glioma cancer cells and is released as a large extracellular ectodomain fragment, which stimulates cell motility and proliferation. This study investigates the effects of ectopic overexpression of the L1 long ectodomain (L1LE; ˜180 kDa) on the motility, proliferation, and differentiation of human neural progenitor cells (HNPs). L1LE was ectopically expressed in HNPs using a lentiviral vector. Surprisingly, overexpression of L1LE resulted in reduced HNP motility in vitro, in stark contrast to the effects on glioma and other cancer cell types. L1LE overexpression resulted in a variable degree of maintenance of HNP proliferation in media without added growth factors but did not increase proliferation. In monolayer culture, HNPs expressed a variety of differentiation markers. L1LE overexpression resulted in loss of glutamine synthetase (GS) and β3-tubulin expression in normal HNP media, and reduced vimentin and increased GS expression in the absence of added growth factors. When co-cultured with chick embryonic brain cell aggregates, HNPs show increased differentiation potential. Some HNPs expressed p-neurofilaments and oligodendrocytic O4, indicating differentiation beyond that in monolayer culture. Most HNP-L1LE cells lost their vimentin and GFAP (glial fibrillary acidic protein) staining, and many cells were positive for astrocytic GS. However, these cells rarely were positive for neuronal markers β3-tubulin or p-neurofilaments, and few HNP oligodendrocyte progenitors were found. These results suggest that unlike for glioma cells, L1LE does not increase HNP cell motility, but rather decreases motility and influences the differentiation of normal brain progenitor cells. Therefore, the effect of L1LE on increasing motility and proliferation appears to be limited to already transformed cells.

Huntington disease (HD) is an autosomal dominant neurodegenerative disorder caused by expanded CAG repeats in the huntingtin gene (HIT). Although mutant HTT is expressed during embryonic development and throughout life, clinical HD usually manifests later in adulthood. A number of studies document neurodevelopmental changes associated with mutant HIT, but whether these are reversible under therapy remains unclear. Here, we identify very early behavioral, molecular, and cellular changes in preweaning transgenic HD rats and mice. Reduced ultrasonic vocalization, loss of prepulse inhibition, and increased risk taking are accompanied by disturbances of dopaminergic regulation in vivo, reduced neuronal differentiation capacity in subventricular zone stem/progenitor cells, and impaired neuronal and oligodendrocyte differentiation of mouse embryo-derived neural stem cells in vitro. Interventional treatment of this early phenotype with the histone deacetylase inhibitor (HDACi) LBH589 led to significant improvement in behavioral changes and markers of dopaminergic neurotransmission and complete reversal of aberrant neuronal differentiation in vitro and in vivo. Our data support the notion that neurodevelopmental changes contribute to the prodromal phase of HD and that early, presymptomatic intervention using HDACi may represent a promising novel treatment approach for HD.

One third of humans are infected lifelong with the brain-dwelling, protozoan parasite, Toxoplasma gondii. Approximately fifteen million of these have congenital toxoplasmosis. Although neurobehavioral disease is associated with seropositivity, causality is unproven. To better understand what this parasite does to human brains, we performed a comprehensive systems analysis of the infected brain: We identified susceptibility genes for congenital toxoplasmosis in our cohort of infected humans and found these genes are expressed in human brain. Transcriptomic and quantitative proteomic analyses of infected human, primary, neuronal stem and monocytic cells revealed effects on neurodevelopment and plasticity in neural, immune, and endocrine networks. These findings were supported by identification of protein and miRNA biomarkers in sera of ill children reflecting brain damage and T. gondii infection. These data were deconvoluted using three systems biology approaches: “Orbital-deconvolution” elucidated upstream, regulatory pathways interconnecting human susceptibility genes, biomarkers, proteomes, and transcriptomes. “Cluster-deconvolution” revealed visual protein-protein interaction clusters involved in processes affecting brain functions and circuitry, including lipid metabolism, leukocyte migration and olfaction. Finally, “disease-deconvolution” identified associations between the parasite-brain interactions and epilepsy, movement disorders, Alzheimer’s disease, and cancer. This “reconstruction-deconvolution” logic provides templates of progenitor cells’ potentiating effects, and components affecting human brain parasitism and diseases.

Glioma stem cells (GSC) and epithelial–mesenchymal transition (EMT) are strongly associated with therapy resistance and tumor recurrence, but the underlying mechanisms are incompletely understood. Here, we show that S100A4 is a novel biomarker of GSCs. S100A4+ cells in gliomas are enriched with cancer cells that have tumor-initiating and sphere-forming abilities, with the majority located in perivascular niches where GSCs are found. Selective ablation of S100A4-expressing cells was sufficient to block tumor growth in vitro and in vivo. We also identified S100A4 as a critical regulator of GSC self-renewal in mouse and patient-derived glioma tumorspheres. In contrast with previous reports of S100A4 as a reporter of EMT, we discovered that S100A4 is an upstream regulator of the master EMT regulators SNAIL2 and ZEB along with other mesenchymal transition regulators in glioblastoma. Overall, our results establish S100A4 as a central node in a molecular network that controls stemness and EMT in glioblastoma, suggesting S100A4 as a candidate therapeutic target. Cancer Res; 77(19); 5360–73. ©2017 AACR.

Extracellular vesicles (EVs) are released from many cell types, including normal and pathological cells, and range from 30 to 1000 nm in size. Once thought to be a mechanism for discarding unwanted cellular material, EVs are now thought to play a role in intercellular communication. Evidence is accruing that EVs are capable of carrying mRNAs, miRNAs, noncoding RNAs, and proteins, including those associated with neurodegenerative diseases and cancer, which may be exchanged between cells. For this reason, neurodegenerative diseases and cancers may share a common mechanism of disease spread via EVs. Understanding the role EVs play in disease initiation and progression will aid in the discovery of new clinically relevant biomarkers and the development of better targeted molecular and biological therapies.

Identifying novel, effective therapeutics for Alzheimer's disease (AD) is one of the major unmet medical needs for the coming decade. Because the current paradigm for developing and testing disease modifying AD therapies is protracted and likely to be even longer with the shift towards earlier intervention in pre-clinical AD, it is an open question whether we can develop, test, and widely deploy a novel therapy in time to help the current at-risk generation if we continue to follow the standard paradigms of discovery and drug development. There is an imperative need to find safe and effective preventative measures that can be rapidly deployed to stem the coming wave of AD that will potentially engulf the next generation. We can broadly define regenerative medicine as approaches that use stem-cell-based therapies or approaches that seek to modulate inherent neurogenesis. Neurogenesis, though most active during pre-natal development has been shown to continue in several small parts of the brain, which includes the hippocampus and the subventricular zone, suggesting its potential to reverse cognitive deficits. If AD pathology impacts neurogenesis then it follows that conditions that stimulate endogenous neurogenesis (e.g., environmental stimuli, physical activity, trophic factors, cytokines, and drugs) may help to promote the regenerative and recovery process. Herein, we review the complex logistics of potentially implementing neurogenesis-based therapeutic strategies for the treatment of AD.

Neural progenitor cells (NPCs) in the subventricular zone (SVZ) hold promise for future therapy for neurodegenerative disorders, because the stimulation of adult neurogenesis could potentially restore the function of degenerating neurons and glia. To obtain more knowledge on these NPCs, we developed a method to specifically isolate NPCs from postmortem adult human brains based on the expression of the specific human adult neural stem/progenitor cell marker glial fibrillary acidic protein δ (GFAPδ). An extensive immunophenotyping analysis for cell surface markers resulted in the observation that CD271 was limited to the SVZ-derived GFAPδ-positive cells. CD271+ cells developed into neurospheres and could be differentiated into astrocytes, neurons, and oligodendrocytes. We are the first to show that a pure population of NPCs can be isolated from the adult human SVZ, which is highly instrumental for developing future therapies based on stimulating endogenous SVZ neurogenesis.

One third of humans are infected lifelong with the brain-dwelling, protozoan parasite, Toxoplasma gondii. Approximately fifteen million of these have congenital toxoplasmosis. Although neurobehavioral disease is associated with seropositivity, causality is unproven. To better understand what this parasite does to human brains, we performed a comprehensive systems analysis of the infected brain: We identified susceptibility genes for congenital toxoplasmosis in our cohort of infected humans and found these genes are expressed in human brain. Transcriptomic and quantitative proteomic analyses of infected human, primary, neuronal stem and monocytic cells revealed effects on neurodevelopment and plasticity in neural, immune, and endocrine networks. These findings were supported by identification of protein and miRNA biomarkers in sera of ill children reflecting brain damage and T. gondii infection. These data were deconvoluted using three systems biology approaches: "Orbital-deconvolution" elucidated upstream, regulatory pathways interconnecting human susceptibility genes, biomarkers, proteomes, and transcriptomes. "Cluster-deconvolution" revealed visual protein-protein interaction clusters involved in processes affecting brain functions and circuitry, including lipid metabolism, leukocyte migration and olfaction. Finally, "disease-deconvolution" identified associations between the parasite-brain interactions and epilepsy, movement disorders, Alzheimer's disease, and cancer. This "reconstruction-deconvolution" logic provides templates of progenitor cells' potentiating effects, and components affecting human brain parasitism and diseases.

Glioblastoma remains one of the most lethal types of cancer, and is the most common brain tumour in adults. In particular, tumour recurrence after surgical resection and radiation invariably occurs regardless of aggressive chemotherapy. Here, we provide evidence that the transcription factor ZEB1 (zinc finger E-box binding homeobox 1) exerts simultaneous influence over invasion, chemoresistance and tumourigenesis in glioblastoma. ZEB1 is preferentially expressed in invasive glioblastoma cells, where the ZEB1-miR-200 feedback loop interconnects these processes through the downstream effectors ROBO1, c-MYB and MGMT. Moreover, ZEB1 expression in glioblastoma patients is predictive of shorter survival and poor Temozolomide response. Our findings indicate that this regulator of epithelial-mesenchymal transition orchestrates key features of cancer stem cells in malignant glioma and identify ROBO1, OLIG2, CD133 and MGMT as novel targets of the ZEB1 pathway. Thus, ZEB1 is an important candidate molecule for glioblastoma recurrence, a marker of invasive tumour cells and a potential therapeutic target, along with its downstream effectors. Glioblastoma have a poor prognosis, mainly due to infiltrating and therapy resistant cells leading to cancer recurrence. Here, tumor formation, invasion and resistance are not independent but intertwined processes regulated by the EMT activator ZEB1.

The presence of stem and progenitor cells in the adult human brain suggests a putative and persistent role in reparative behaviors following neurological injury and neurological disease. Too few stem/progenitor cells (as in the case of Parkinson's disease) or too many of these cells (as in the case of Huntington's disease and glioma) could contribute to and even signal brain pathology. We address here critical issues faced by the field of stem cell biology and regenerative medicine, arguing from well-documented as well as speculative perspectives for a potential role for stem cells in the pathology of many human neurological diseases. Although stem cell responses may result in regenerative failure, in many cases they may help in the establishment or re-establishment of a functional neural circuitry (eg, after stroke). Therefore, we would argue that stem cells have a crucial-either positive or negative-role in the pathology of many neurological diseases.

Cerebellar Purkinje neurons (PNs) possess a well characterized propensity to fuse with bone marrow-derived cells (BMDCs), producing heterokaryons with Purkinje cell identities. This offers the potential to rescue/repair at risk or degenerating PNs in the inherited ataxias, including Spinocerebellar Ataxia 1 (SCA1), by introducing therapeutic factors through BMDCs to potentially halt or reverse disease progression. In this study, we combined gene therapy and a stem cell-based treatment to attempt repair of at-risk PNs through cell-cell fusion in a Sca1(154Q/2Q) knock-in mouse model. BMDCs enriched for the hematopoietic stem cell (HSC) population were genetically modified using adeno-associated viral vector 7 (AAV7) to carry SCA1 modifier genes and transplanted into irradiated Sca1(154Q/2Q) mice. Binucleated Purkinje heterokaryons with sex-mismatched donor Y chromosomes were detected and successfully expressed the modifier genes in vivo. Potential effects of the new genome within Purkinje heterokaryons were evaluated using nuclear inclusions (NIs) as a biological marker to reflect possible modifications of the SCA1 disease process. An overall decrease in number of NIs and an increase in the number of surviving PNs were observed in treated Sca1(154Q/2Q). Furthermore, Bergmann glia were found to have fusogenic potential with the donor population and reveal another potential route of therapeutic entry into at-risk cells of the SCA1 cerebellum. This study presents a first step towards a proof-of-principle that combines somatic cellular fusion events with a neuroprotective gene therapy approach for providing potential neuronal protection/repair in a variety of neurodegenerative disorders.

Over 70,000 DBS devices have been implanted worldwide; however, there remains a paucity of well-characterized post-mortem DBS brains available to researchers. We propose that the overall understanding of DBS can be improved through the establishment of a Deep Brain Stimulation-Brain Tissue Network (DBS-BTN), which will further our understanding of DBS and brain function. The objectives of the tissue bank are twofold: (a) to provide a complete (clinical, imaging and pathological) database for DBS brain tissue samples, and (b) to make available DBS tissue samples to researchers, which will help our understanding of disease and underlying brain circuitry. Standard operating procedures for processing DBS brains were developed as part of the pilot project. Complete data files were created for individual patients and included demographic information, clinical information, imaging data, pathology, and DBS lead locations/settings. 19 DBS brains were collected from 11 geographically dispersed centers from across the U.S. The average age at the time of death was 69.3 years (51-92, with a standard deviation or SD of 10.13). The male:female ratio was almost 3:1. Average post-mortem interval from death to brain collection was 10.6 h (SD of 7.17). The DBS targets included: subthalamic nucleus, globus pallidus interna, and ventralis intermedius nucleus of the thalamus. In 16.7% of cases the clinical diagnosis failed to match the pathological diagnosis. We provide neuropathological findings from the cohort, and perilead responses to DBS. One of the most important observations made in this pilot study was the missing data, which was approximately 25% of all available data fields. Preliminary results demonstrated the feasibility and utility of creating a National DBS-BTN resource for the scientific community. We plan to improve our techniques to remedy omitted clinical/research data, and expand the Network to include a larger donor pool. We will enhance sample preparation to facilitate advanced molecular studies and progenitor cell retrieval.

We explored the nature of the tumor-initiating cell in osteosarcoma, a bone malignancy that predominately occurs in children. Previously, we observed expression of Oct-4, an embryonal transcriptional regulator, in osteosarcoma cell cultures and tissues. To examine the relationship between Oct-4 and tumorigenesis, cells from an osteosarcoma biopsy (OS521) were stably transfected with a plasmid containing the human Oct-4 promoter driving a green fluorescent protein (GFP) reporter to generate the transgenic line OS521Oct-4p. In culture, only ∼24% of the OS521Oct-4p cells were capable of activating the transgenic Oct-4 promoter; yet, xenograft tumors generated in NOD/SCID mice contained ∼67% GFP+ cells, which selectively expressed the mesenchymal stem cell–associated surface antigens CD105 and ICAM-1. Comparison of the tumor-forming capacity of GFP-enriched and GFP-depleted cell fractions revealed that the GFP-enriched fractions were at least 100-fold more tumorigenic, capable of forming tumors at doses of

Microglia, the resident immune cells of the brain, have recently been hypothesized to play a role both in neuronal diseases and age related neurogenic decline, and are theorized to be modulators of adult neurogenesis. Current methods for the isolation of microglia from cultured primary brain tissue result in relatively poor yield, requiring a large tissue sample or multiple specimens in order to obtain a sufficient number of microglia for cell and molecular analysis. We report here a method for the repetitive isolation of microglia from established glial monolayer cultures from which it is possible to expand the initial population of microglia roughly 10,000 fold. The expanded population expresses appropriate microglial morphology and phenotype markers, and demonstrates functionally normal phagocytosis, thus providing a high-yield assay for the investigation and analysis of microglia from a single initial dissection of primary tissue. Furthermore, this massive expansion is limited to microglia derived from the subventricular zone as the fold expansion of isolatable microglia was found to be up to 20 times greater than cultures from other brain regions, indicating unique properties for this persistently neurogenic region.

Purpose: Investigation of clonal heterogeneity may be key to understanding mechanisms of therapeutic failure in human cancer. However, little is known on the consequences of therapeutic intervention on the clonal composition of solid tumors. Experimental Design: Here, we used 33 single cell–derived subclones generated from five clinical glioblastoma specimens for exploring intra- and interindividual spectra of drug resistance profiles in vitro. In a personalized setting, we explored whether differences in pharmacologic sensitivity among subclones could be employed to predict drug-dependent changes to the clonal composition of tumors. Results: Subclones from individual tumors exhibited a remarkable heterogeneity of drug resistance to a library of potential antiglioblastoma compounds. A more comprehensive intratumoral analysis revealed that stable genetic and phenotypic characteristics of coexisting subclones could be correlated with distinct drug sensitivity profiles. The data obtained from differential drug response analysis could be employed to predict clonal population shifts within the naïve parental tumor in vitro and in orthotopic xenografts. Furthermore, the value of pharmacologic profiles could be shown for establishing rational strategies for individualized secondary lines of treatment. Conclusions: Our data provide a previously unrecognized strategy for revealing functional consequences of intratumor heterogeneity by enabling predictive modeling of treatment-related subclone dynamics in human glioblastoma. Clin Cancer Res; 23(2); 562–74. ©2016 AACR.

Slice culture model systems provide a unique opportunity to monitor and lesion brain circuits in a dish. Using a novel approach, we have generated parasagittal slices from mouse brains that preserve, throughout the culture process, the nigrostriatal circuit. These slices can be cultured for approximately 4 weeks with maintenance of normal neuronal cytoarchitecture. Application of the dopamine specific toxin 6-hydroxy dopamine (6-OHDA) induces a significant decline in tyrosine hydroxylase positive cell bodies and fibers. Using a transgenic mouse with green fluorescent protein (GFP) under the control of the tyrosine hydroxylase promoter, we have been able to visualize in real time the loss of GFP expression in the striatum of slices as a result of 6-OHDA exposure. Using these cultures we have demonstrated the feasibility of modeling cellular replacement strategies. GFP-positive embryonic stem cell-derived neuronal precursors can be tracked in real time throughout the experiment and are amenable to patch clamp recording within the slice environment. In addition, cell differentiation can be observed within these slices and the effects of morphogenetic proteins, like the extracellular matrix molecule laminin, drugs or small molecules can be observed. This unique culture system presents a new approach for modeling Parkinson's disease in vitro, and provides a potentially useful new method for screening cell and molecular therapies for neurodegenerative diseases.

Hypoxic-ischemic encephalopathy (HIE) in neonates results in long-term disabilities. Stem cell therapy may offer an attractive treatment for HIE. Multipotent astrocytic stem cells (MASCs) from mice transplanted into a rat model of hypoxia-ischemia (HI) survived the transplantation and showed signs of migration towards the injured cortex. Some MASCs around the injured cortex differentiated into neuronal and astrocytic phenotypes. MASCs transplanted into non-ischemic pups survived but retained their astrocytic phenotype. These data suggest that transplanted MASCs can survive and differentiate into neurons and astrocytes in the post-injury milieu of the neonatal brain injured by HI.

Brain slices provide a useful nervous tissue model to investigate the relationships between magnetic resonance imaging (MRI) contrast mechanisms and tissue microstructure; yet, these acutely isolated tissues remain viable for only 10–12 h. To study slower biological processes, this work describes the first MRI microscopy characterization of organotypic rat hippocampal slice cultures that can be maintained for several weeks. Diffusion-weighted images of slice cultures acquired with a 14.1-T magnet demonstrated the laminar anatomy of the hippocampus with relatively high signal-to-noise ratios. Diffusion data analyzed using a two-compartment model with exchange indicated that cultured slices had a comparable microstructure to acute brain slices and to in vivo brain. Immunohistochemistry indicated that slice cultures tolerated the conditions required for MRI study well. MRI of cultured tissue slices is highly amenable to correlative microscopy techniques and offers great promise for future MRI investigations of pathological tissue reorganization, molecular imaging and stem cell therapies.

The subependymal zone (SEZ) is a region of persistent neurogenesis in the adult mammalian brain containing a neural stem cell (NSC) pool that continuously generates migratory neuroblasts that travel in chains through the rostral migratory stream (RMS) to the olfactory bulb (OB), where they differentiate and functionally integrate into existing neural circuitry. NSCs can be isolated from the SEZ and cultured to generate either neurospheres (NSs) or multipotent astrocytic stem cells (MASCs), with both possessing the stem cell characteristics of multipotency and self-renewal. NSs and MASCs home to the SEZ after transplantation into the lateral ventricle (LV) and contribute to neuroblast migration, with minimal engraftment into the OB observed in the adult mouse. Recent studies have compared the relatively uncharacterized NSC with the more established hematopoietic stem cell (HSC) in an effort to determine the level of stemness possessed by the NSC. Depletion of native HSCs in the bone marrow by lethal irradiation (LI) is necessary to maximize functional engraftment of donor HSCs. Our data show that the NSC pool and neuroblasts in the SEZ can be significantly and permanently depleted by exposure to LI. Attenuation of donor-derived migratory neuroblast engraftment into the OB is observed after transplantation of gfp+ MASCs into the LV of LI animals, whereas engraftment is significantly enhanced after transplantation into animals exposed to sublethal levels of ionizing radiation. By increasing receptiveness of the NSC niche through depletion of indigenous cells, the adult SEZ-RMS-OB can be used as a model to further characterize the NSC.

GM1-ganglioside (GM1) is a major sialoglycolipid of neuronal membranes that, among other functions, modulates calcium homeostasis. Excessive accumulation of GM1 due to deficiency of lysosomal beta-galactosidase (beta-gal) characterizes the neurodegenerative disease GM1-gangliosidosis, but whether the accumulation of GM1 is directly responsible for CNS pathogenesis was unknown. Here we demonstrate that activation of an unfolded protein response (UPR) associated with the upregulation of BiP and CHOP and the activation of JNK2 and caspase-12 leads to neuronal apoptosis in the mouse model of GM1-gangliosidosis. GM1 loading of wild-type neurospheres recapitulated the phenotype of beta-gal-/- cells and activated this pathway by depleting ER calcium stores, which ultimately culminated in apoptosis. Activation of UPR pathways did not occur in mice double deficient for beta-gal and ganglioside synthase, beta-gal-/-/GalNAcT-/-, which do not accumulate GM1. These findings suggest that the UPR can be induced by accumulation of the sialoglycolipid GM1 and this causes a novel mechanism of neuronal apoptosis.

Summary Background End-organ repair by adult haemopoietic stem cells is under great scrutiny with investigators challenging the notion of these cells' plasticity. Some investigations of animals and short-term human bone marrow transplants suggest that bone marrow can repair brain. We looked for evidence of clinically relevant marrow-derived restorative neurogenesis: long-term, multilineage, neural engraftment that is not the result of cell-fusion events. Methods We examined autopsy brain specimens from three sex-mismatched female bone-marrow-transplantation patients, a female control, and a male control. We did immunohistochemistry, fluorescence in-situ hybridisation, and tissue analysis to look for multilineage, donor-derived neurogenesis. Findings Hippocampal cells containing a Y chromosome were present up to 6 years post-transplant in all three patients. Transgender neurons accounted for 1% of all neurons; there was no evidence of fusion events since only one X chromosome was present. Moreover, transgender astrocytes and microglia made up 1–2% of all glial cells. Interpretation Postnatal human neuropoiesis happens, and human haemopoietic cells can transdifferentiate into neurons, astrocytes, and microglia in a long-term setting without fusing. Transplantable human haemopoietic cells could serve as a therapeutic source for long-term regenerative neuropoiesis.

An important milestone in brain development is the transition of neuroprogenitor cells to postmitotic neurons. We report that the bZIP transcription factor ATF5 plays a major regulatory role in this process. In developing brain ATF5 expression is high within ventricular zones containing neural stem and progenitor cells and is undetectable in postmitotic neurons. In attached clonal neurosphere cultures ATF5 is expressed by neural stem/progenitor cells and is undetectable in tau-positive neurons. In PC12 cell cultures nerve growth factor (NGF) dramatically downregulates endogenous ATF5 protein and transcripts, whereas exogenous ATF5 suppresses NGF-promoted neurite outgrowth. Such inhibition requires the repression of CRE sites. In contrast, loss of function conferred by dominant-negative ATF5 accelerates NGF-promoted neuritogenesis. Exogenous ATF5 also suppresses, and dominant-negative ATF5 and a small-interfering RNA targeted to ATF5 promote, neurogenesis by cultured nestin-positive telencephalic cells. These findings indicate that ATF5 blocks the differentiation of neuroprogenitor cells into neurons and must be downregulated to permit this process to occur.

Neural stem cells from neurogenic regions of mammalian CNS are clonogenic in an in vitro culture system exploiting serum and anchorage withdrawal in medium supplemented with methyl cellulose and the pleiotropic growth factors EGF, FGF2, and insulin. The aim of this study was to test whether cortical glial tumors contain stem-like cells capable, under this culture system, of forming clones showing intraclonal heterogeneity in the expression of neural lineage-specific proteins. The high frequencies of clone-forming cells (about 0.1-10 x 10(-3)) in clinical tumor specimens with mutated p53, and in neurogenic regions of normal human CNS, suggest that the ability to form clones in this culture system is induced epigenetically. RT-PCR analyses of populations of normal brain- and tumor-derived sister clones revealed transcripts for nestin, neuron-specific enolase, and glial fibrillary acidic protein (GFAP). However, the tumor-derived clones were different from clones derived from neurogenic regions of normal brain in the expression of transcripts specific for genes associated with neural cell fate determination via the Notch-signaling pathway (Delta and Jagged), and cell survival at G2 or mitotic phases (Survivin). Moreover, the individual glioma-derived clones contain cells immunopositive separately for GFAP or neuronal beta-III tubulin, as well as single cells coexpressing both glial and neuronal markers. The data suggest that the latent critical stem cell characteristics can be epigenetically induced by growth conditions not only in cells from neurogenic regions of normal CNS but also in cells from cortical glial tumors. Moreover, tumor stem-like cells with genetically defective responses to epigenetic stimuli may contribute to gliomagenesis and the developmental pathological heterogeneity of glial tumors.

Stem cells in adult tissues have attracted a great deal of interest. These cells are self-renewing and can give rise to diverse progeny. An extraordinary finding was the presence of stem cells in the mature human brain. This tissue was previously believed incapable of generating new neurons, but neuropoiesis is now an established phenomenon in the adult brains of mammals, including human beings. This persistent neurogenesis has potential therapeutic applications for various neurological disorders as a source for tissue engraftment and as self-repair by a person's own indigenous population of pluripotent cells or biogenic by-products of their proliferation and differentiation.

Glioblastoma, the most frequent primary malignancy of the central nervous system, is almost universally fatal despite aggressive therapies, such as surgical resection, adjuvant radiation and chemotherapy, which remain largely palliative. With increasing evidence showing that glioblastoma cancer stem cells play an important role in tumor escape from conventional therapies and disease recurrence, the targeting of cancer stem cells with different therapeutic strategies provides new avenues of research and confidence for better outcomes. We have previously shown that isolating slow-dividing cells from glioblastoma enriches for a population with cancer stem cell properties. Here, we demonstrate that these slow-dividing cancer stem cells are more invasive and more tolerant to chemotherapy than the rest of the tumor population. Surprisingly, slow-proliferating cells are initially more sensitive to radiation damage. We find a significant overlap between the slow-proliferating compartment and expression of the transcription factor ZEB1, which we have recently identified as a master regulator of stemness and chemoresistance in glioblastoma. Consequently, ZEB1-positive cells also exhibit greater radiosensitivity. Slow proliferating, ZEB1-positive cells accumulate genomic aberrations correlated with retention in the G2/M phase of the cell cycle, rendering these cells more sensitive to radiation damage. However, from this specific subpopulation, a fraction of cells that survive irradiation rebound with a proliferative burst that may contribute to recurrence of more aggressive tumors. This distinct effect of radiation on cancer stem cells points to a previously underappreciated heterogeneity within the cancer stem cell compartment and may open up new avenues of studying and targeting specific cancer stem cell sub-populations.

Microglia isolated from the neurogenic subependymal zone (SEZ) and hippocampus (HC) are capable of massive in vitro population expansion that is not possible with microglia isolated from non-neurogenic regions. We asked if this regional heterogeneity in microglial proliferative capacity is cell intrinsic, or is conferred by interaction with respective neurogenic or non-neurogenic niches. By combining SEZ and cerebral cortex (CTX) primary tissue dissociates to generate heterospatial cultures, we find that exposure to the SEZ environment does not enhance CTX microglia expansion; however, the CTX environment exerts a suppressive effect on SEZ microglia expansion. Furthermore, addition of purified donor SEZ microglia to either CTX- or SEZ-derived cultures suppresses the expansion of host microglia, while the addition of donor CTX microglia enhances the over-all microglia yield. These data suggest that SEZ and CTX microglia possess intrinsic, spatially restricted characteristics that are independent of their in vitro environment, and that they represent unique and functionally distinct populations. Finally, we determined that the repeated supplementation of neurogenic SEZ cultures with expanded SEZ microglia allows for sustained levels of inducible neurogenesis, provided that the ratio of microglia to total cells remains within a fairly narrow range.

Objective\ud Deep brain stimulation (DBS) has been used for more than a decade to treat Parkinson's disease (PD); however, its mechanism of action remains unknown. Given the close proximity of the electrode trajectory to areas of the brain known as the “germinal niches,” we sought to explore the possibility that DBS influences neural stem cell proliferation locally, as well as more distantly.\ud \ud Methods\ud We studied the brains of a total of 12 idiopathic Parkinson's disease patients that were treated with DBS (the electrode placement occurred 0.5–6 years before death), and who subsequently died of unrelated illnesses. These were compared to the brains of 10 control individuals without CNS disease, and those of 5 PD patients with no DBS.\ud \ud Results\ud Immunohistochemical analyses of the subventricular zone (SVZ) of the lateral ventricles, the third ventricle lining, and the tissue surrounding the DBS lead revealed significantly greater numbers of proliferating cells expressing markers of the cell cycle, plasticity, and neural precursor cells in PD-DBS tissue compared with both normal brain tissue and tissue from PD patients not treated with DBS. The level of cell proliferation in the SVZ in PD-DBS brains was 2–6 fold greater than that in normal and untreated PD brains.\ud \ud Conclusions\ud Our data suggest that DBS is capable of increasing cellular plasticity in the brain, and we hypothesize that it may have more widespread effects beyond the electrode location. It is unclear whether these effects of DBS have any symptomatic or other beneficial influences on PD.

A transgenic mouse containing the first exon of the human Huntington's disease (HD) gene has revealed a variety of behavioral and pathophysiological anomalies reminiscent of certain aspects of human Huntington's disease (HD). The present study has found that expression of the extracellular matrix glycoprotein tenascin-C appears to be unaffected in astroglial cells in wild-type and R6/2 transgenic mice that express the mutant huntingtin protein but that it is conspicuously absent in two neuronal populations within the cerebral cortex and thalamus of the R6/2 mice. Loss of tenascin-C expression begins between the fourth and eighth postnatal weeks, coincidental with the onset of abnormal behavioral phenotype and the appearance of intranuclear inclusion bodies and neuropil aggregates. By 12 weeks, R6/2 mice exhibit a complete absence of tenascin-C neuronal immunolabeling, a disappearance of cRNA probe-positive neurons across discrete cytoarchitectonic regions of the dorsal thalamus (e.g., the ventromedial, parafascicular, lateral posterior, and posterior thalamic groups) and frontal cortex, and an accompanying thalamic astrogliosis. The loss of neuronal tenascin-C expression includes structures that are known to send converging excitatory axonal projections to the caudate-putamen, the structure that is most at risk for neurodegeneration in HD. Altered neuronal expression of tenascin-C in R6/2 mice implicates altered transcriptional activities of the mutant huntingtin protein. The abnormal biochemistry and possibly abnormal activity of thalamostriate and corticostriate projection neurons may also affect abnormal neuronal activities in their primary connectional target, the neostriatum, which is severely compromised in HD. J. Comp. Neurol. 430:485–500, 2001. © 2001 Wiley-Liss, Inc.

The mammalian brain contains a population of neural stem cells (NSC) that can both self-renew and generate progeny along the three lineage pathways of the central nervous system (CNS), but the in vivo identification and localization of NSC in the postnatal CNS has proved elusive. Recently, separate studies have implicated ciliated ependymal (CE) cells, and special subependymal zone (SEZ) astrocytes as candidates for NSC in the adult brain. In the present study, we have examined the potential of these two NSC candidates to form multipotent spherical clones—neurospheres— in vitro . We conclude that CE cells are unipotent and give rise only to cells within the glia cell lineage, although they are capable of forming spherical clones when cultured in isolation. In contrast, astrocyte monolayers from the cerebral cortex, cerebellum, spinal cord, and SEZ can form neurospheres that give rise both to neurons and glia. However, the ability to form neurospheres is restricted to astrocyte monolayers derived during the first 2 postnatal wk, except for SEZ astrocytes, which retain this capacity in the mature forebrain. We conclude that environmental factors, simulated by certain in vitro conditions, transiently confer NSC-like attributes on astrocytes during a critical period in CNS development.

The adult mammalian CNS harbors a population of multipotent stem/progenitor cells that can be induced to grow as proliferative neurospheresin vitro.We demonstrate here that neurosphere-generating cells can be isolated from adult mouse spinal cord and forebrain subependymal zone after postmortem intervals of up to 140 h, when kept at 4°C, and up to 30 h when kept at room temperature. Although there was an inverse relationship between postmortem interval and the number of neurospheres generated, neurospheres derived under these conditions were proliferative and could give rise to both neurons and glia.

Glioblastoma (GBM) is the most common malignant adult brain tumor and carries a poor prognosis due to primary and acquired resistance. While many cellular features of GBM have been documented, it is unclear if cells within these tumors extend a primary cilium, an organelle whose associated signaling pathways may regulate proliferation, migration, and survival of neural precursor and tumor cells. Using immunohistochemical and electron microscopy (EM) techniques, we screened human GBM tumor biopsies and primary cell lines for cilia. Immunocytochemical staining of five primary GBM cell lines revealed that between 8 and 25 % of the cells in each line possessed gamma tubulin-positive basal bodies from which extended acetylated, alpha-tubulin-positive axonemes. EM analyses confirmed the presence of cilia at the cell surface and revealed that their axonemes contained organized networks of microtubules, a structural feature consistent with our detection of IFT88 and Arl13b, two trafficked cilia proteins, along the lengths of the axonemes. Notably, cilia were detected in each of 23 tumor biopsies (22 primary and 1 recurrent) examined. These cilia were distributed across the tumor landscape including regions proximal to the vasculature and within necrotic areas. Moreover, ciliated cells within these tumors co-stained with Ki67, a marker for actively dividing cells, and ZEB1, a transcription factor that is upregulated in GBM and linked to tumor initiation, invasion, and chemoresistance. Collectively, our data show that subpopulations of cells within human GBM tumors are ciliated. In view of mounting evidence supporting roles of primary cilia in tumor initiation and propagation, it is likely that further study of the effects of cilia on GBM tumor cell function will improve our understanding of GBM pathogenesis and may provide new directions for GBM treatment strategies.

Using a novel suspension culture approach, previously undescribed populations of neural precursor cells have been isolated from the adult mouse brain. Recent studies have shown that neuronal and glial precursor cells proliferate within the subependymal zone of the lateral ventricle throughout life, and a persistent expression of developmentally regulated surface and extracellular matrix molecules implicates cell-cell and cell-substrate interactions in the proliferation, migration, and differentiation of these cells. By using reagents that may affect cell-cell interactions, dissociated adult brain yields two types of cell aggregates, type I and type II spheres. Both sphere types are proliferative, and type I spheres evolve into type II spheres. Neurons and glia arise from presumptive stem cells of type II spheres, and they can survive transplantation to the adult brain.

A recent study by Mitrovic and Schachner (J Neurosci Res 42:710-717, 1995) reported the detection of a small amount of truncated tensacin-C (TN-C) in the nervous system of the TN-C knockout mice created by Saga et al. (Genes Dev 6:1821-1831, 1992). The authors suggested that the truncated protein might be responsible for the failure to detect any phenotypic abnormalities in the knockout mice. We have reexamined the knockout mice in our laboratories by Western blot and immunocytochemistry, and have not detected any full-length or truncated TN-C protein. In addition, we note that the construction of the knockout gene deleted the signal sequence, so if any residual truncated protein were produced it would be trapped in the cytoplasm, and therefore inaccessible to extracellular ligands or receptors. We therefore conclude that the TN-C knockout created by Saga et al. is a valid TN-C null.

Glioblastoma (GBM) remains the most pervasive and lethal of all brain malignancies. One factor that contributes to this poor prognosis is the highly invasive character of the tumor. GBM is characterized by microscopic infiltration of tumor cells throughout the brain, whereas non-neural metastases, as well as select lower grade gliomas, develop as self-contained and clearly delineated lesions. Illustrated by rodent xenograft tumor models as well as pathological human patient specimens, we present evidence that one fundamental switch between these two distinct pathologies–invasion and noninvasion–is mediated through the tumor extracellular matrix. Specifically, noninvasive lesions are associated with a rich matrix containing substantial amounts of glycosylated chondroitin sulfate proteoglycans (CSPGs), whereas glycosylated CSPGs are essentially absent from diffusely infiltrating tumors. CSPGs, acting as central organizers of the tumor microenvironment, dramatically influence resident reactive astrocytes, inducing their exodus from the tumor mass and the resultant encapsulation of noninvasive lesions. Additionally, CSPGs induce activation of tumor-associated microglia. We demonstrate that the astrogliotic capsule can directly inhibit tumor invasion, and its absence from GBM presents an environment favorable to diffuse infiltration. We also identify the leukocyte common antigen-related phosphatase receptor (PTPRF) as a putative intermediary between extracellular glycosylated CSPGs and noninvasive tumor cells. In all, we present CSPGs as critical regulators of brain tumor histopathology and help to clarify the role of the tumor microenvironment in brain tumor invasion.

Purpose: Glioblastoma is a highly malignant, invariably fatal brain tumor for which effective pharmacotherapy remains an unmet medical need. Experimental Design: Screening of a compound library of 160 synthetic and natural toxic substances identified the antihelmintic niclosamide as a previously unrecognized candidate for clinical development. Considering the cellular and interindividual heterogeneity of glioblastoma, a portfolio of short-term expanded primary human glioblastoma cells (pGBM; n = 21), common glioma lines (n = 5), and noncancer human control cells (n = 3) was applied as a discovery platform and for preclinical validation. Pharmacodynamic analysis, study of cell-cycle progression, apoptosis, cell migration, proliferation, and on the frequency of multipotent/self-renewing pGBM cells were conducted in vitro, and orthotopic xenotransplantation was used to confirm anticancer effects in vivo. Results: Niclosamide led to cytostatic, cytotoxic, and antimigratory effects, strongly reduced the frequencies of multipotent/self-renewing cells in vitro, and after exposure significantly diminished the pGBMs' malignant potential in vivo. Mechanism of action analysis revealed that niclosamide simultaneously inhibited intracellular WNT/CTNNB1-, NOTCH-, mTOR-, and NF-κB signaling cascades. Furthermore, combinatorial drug testing established that a heterozygous deletion of the NFKBIA locus in glioblastoma samples could serve as a genomic biomarker for predicting a synergistic activity of niclosamide with temozolomide, the current standard in glioblastoma therapy. Conclusions: Together, our data advocate the use of pGBMs for exploration of compound libraries to reveal unexpected leads, for example, niclosamide that might be suited for further development toward personalized clinical application. Clin Cancer Res; 19(15); 4124–36. ©2013 AACR.

Previous studies describing the use of cryoculture methods have focused on the efficacy of the method for studying neuron attachment and neurite outgrowth on intact sections of nerve, and rodent and even human brain. The cryoculture method has shown promise for determining the presence of cell attachment- and neurite-growth-inhibiting molecules in such specimens, and some studies have also attempted to neutralize such molecules with antibodies to myelin inhibitory proteins, nerve growth factor, or factors present in conditioned media that may counteract the repulsiveness of some of these molecules preserved in sections of, for example, myelinated nerves or adult brain white matter. The present study describes the novel use of lesioned central nervous system cryocultures as substrates for investigating the attachment of embryonic neurons and PC12 cells. In addition to demonstrating the use of this novel scar substrate to extend previous ‘scar-in-a-dish’ models (David et al. (1990) Neuron, 5: 463–469; Rudge and Silver (1990) J. Neurosci., 10: 3594–3603; Rudge et al. (1989) Exp. Neurol., 103: 1–16), the present study also describes antibody and lectin perturbations of putative inhibitory molecules that result in an enhanced attachment of cells to cryosection cultures of brain and spinal cord wounds.

The subependymal zone (SEZ) of the lateral ventricle of adult rodents has long been known to be mitotically active. There has been increased interest in the SEZ, since it has been demonstrated that neuroepithelial stem cells residing there generate neurons in addition to glia in vitro. In the present study, we have examined parasagittal sections of the adult mouse brain using immunocytochemistry for extracellular matrix (ECM) molecules (tenascin and chondroitin sulfate-containing proteoglycans), glial fibrillary acidic protein (GFAP, a cytoskeletal protein prominently expressed by immature and reactive astrocytes), RC-2 (a radial glial and immature astrocyte cytoskeletal marker), TuJ1 (a class III beta-tubulin isoform expressed solely by postmitotic and adult neurons), nestin (a cytoskeletal protein associated with stem cells), neuron-specific enolase, and bromodeoxyuridine (BrdU, which is taken up by dividing cells). Our results demonstrate that a population of young neurons reside within an ECM-rich, GFAP-positive astrocyte pathway from the rostral SEZ all the way into the olfactory bulb. Furthermore, BrdU labeling studies indicate that there is a high level of cell division along the entire length of this path, and double-labeling studies indicate that neurons committed to a neuronal lineage (i.e., TuJ1+) take up BrdU (suggesting they are in the DNA synthesis phase of the cell cycle), again along the entire length of the SEZ "migratory pathway." Thus, the SEZ appears to retain the ability to produce neurons and glia throughout the life of the animal, functioning as a type of "brain marrow." The implications of these findings are discussed in relation to the role that such a glial/ ECM-rich boundary (as seen in the embryonic cortical subplate and other developing areas) may play in: confining the migratory populations and maintaining them in a persistent state of immaturity; facilitating their migration to the olfactory bulb, where they are incorporated into established adult circuitries; and potentially altering SEZ cell cycle dynamics that eventually lead to cell death.

Adult neural precursor cells are an essential part of the brain, and a focus of two decades of intense research (Ming and Song, Neuron 70:687-702, 2011). Even though adult human stem/progenitor cells have been identified early on (Kirschenbaum et al., Cereb Cortex 4:576-589, 1994; Eriksson et al., Nat Med 4:1313-1317, 1998), progress in the field of adult human neurogenesis has been slow. The reasons for this may be more advanced neighboring fields of pluripotent stem cell research, and lacking study material as well as well-established and standardized protocols. Furthermore, adult precursor cells in humans seem to have greater potential than in rodents (Walton et al., Development 133:3671-3681, 2006). This may be attributed to species differences in astrocyte development and diversity (Oberheim et al., Neurosci 29:3276-3287, 2009).In this chapter, we provide a guideline for adult human brain tissue dissociation, be it from biopsy or autopsy specimens. This is by no means the only way of culturing adult neural precursor cells, but it may help in streamlining research on this fascinating topic, as well as help introducing others into this field. We describe our methodology for establishing and maintaining long-term cultures from white and grey matter, as well as a simple protocol for differentiating these cells.

The subventricular zone (SVZ) of the lateral ventricle remains mitotically active in the adult mammalian central nervous system (CNS). Recent studies have suggested that this region may contain neuronal precursors (neural stem cells) in adult rodents. A variety of neuronal and glial markers as well as three extracellular matrix (ECM) markers were examined with the hope of understanding factors that may affect the growth and migration of neurons from this region throughout development and in the adult. This study has characterized the subventricular zone of late embryonic, postnatal, and adult mice using several neuronal markers [TuJ1, nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d), neuron- specific enolase (NSE)], glial markers [RC-2, vimentin, glial fibrillary acidic protein (GFAP), galactocerebroside (Gal-C)], ECM markers [tenascin-C (TN-C), chondroitin sulfate, a chondroi tin sulfate proteoglycan termed dermatan sulfate-dependent proteoglycan-1 (DSD-1-PG)], stem-cell marker (nestin), and proliferation-specific marker [bromodeoxyuridine (BrdU)]. TuJ1+ and nestin+ cells (neurons and stem cells, respectively) persist in the region into adulthood, although the numbers of these cells become more sparse as the animal develops, and they appear to be immature compared to the cells in surrounding forebrain structures (e. g., not expressing NSE and having few, if any, processes). Likewise, NADPH-d+ cells are found in and around the SVZ during early postnatal development but become more sparse in the prolifera tive zone through maturity, and, by adulthood, only a few labeled cells can be found at the border between the SVZ and surrounding forebrain structures (e. g., the striatum), and even smaller numbers of positive cells can be found within the adult SVZ proper. BrdU labeling also seems to decrease significantly after the first postnatal week, but it still persists in the SVZ of adult animals. The disappearance of RC-2+ (radial) glia during postnatal development and the persistence of glial-derived ECM molecules such as tenascin and chondroitin sulfate proteoglycans (as well as other “boundary” molecules) in the adult SVZ may be associated with a persistence of immaturity, cell death, and a lack of cell emigration from the SVZ in the adult. © 1995 Wiley-Liss, Inc.

Deoxyribonucleic acid of cells undergoing apoptosis is cleaved by a calcium-dependent endonuclease into oligonucleosomal-sized fragments. These fragments can be labeled using the enzyme terminal deoxynucleotidyl transferase so that the cells can be visualized immunohistochemically. Few investigators have evaluated this method in disease processes of the human central nervous system. The Tdt-mediated dUTP-biotin nick end labeling (TUNEL) technique has been investigated in preliminary studies of a variety of pathologic conditions of the human brain (e.g., gliomas, traumatic brain injury, Parkinson's disease, Parkinson's-Alzheimer's complex, multisystem atrophy, striatonigral degeneration). We focus, however, on Huntington's disease (HD) because of the availability of well-characterized pathological stages for study, and also because of the neurodegenerative diseases studied to date, only Huntington's disease revealed significant and consistent labeling with this method. This implies a possibly unique nature to the mechanism of cell death in Huntington's disease compared to the other neurodegenerative diseases studied. TUNEL+ neurons were found in Grade 1-4 HD neostriatum, while labeled astrocytes were found predominantly in the Grade 1 and 2 cases studied to date. TUNEL+ cells were also found in glioblastoma multiforme and traumatic brain injury. We conclude that while there appear to be several limitations associated with this technique, it may be useful for identifying both apoptosis and necrosis in certain neuropathological conditions.

Early studies of glial boundaries, which are composed of immature astrocytes and extracellular matrix mol ecules (which they express), initially offered insight into the partitioning that occurs in the developing nervous system. More recently, however, it has been suggested that similar "boundaries" may have important roles in other processes occurring in the brain, including repair after traumatic brain injury. As more is understood about the expression and function of boundary molecules and glia, their potential importance is becoming apparent in numerous neuropathological conditions, including neurodegeneration and neuroregeneration in Alzheimer's and Huntington's diseases as well as in brain neoplasms. Furthermore, before we can hope to fully understand and facilitate regeneration in the compromised brain, our knowledge of the glial boundary, both during development and in the adult, must be more complete. The Neuroscientist 1:142-154, 1995

✓ Tenascin is an extracellular matrix glycoprotein expressed during both normal development and neoplastic growth in both neural and nonneural tissues. During development of the central nervous system (CNS), tenascin is synthesized by glial cells, in particular by immature astrocytes, and is concentrated in transient boundaries around emerging groups of functionally distinct neurons. In the mature CNS, only low levels of the glycoprotein can be detected. The present study demonstrates that following trauma to the adult human cerebral cortex, discrete populations of reactive astrocytes upregulate their expression of tenascin and dramatically increase their transcription of the tenascin gene. The enhanced expression of tenascin may be involved in CNS wound healing, and may also affect neurite growth within and around a brain lesion.

Despite remarkable effectiveness of reperfusion and drug therapies to reduce morbidity and mortality following myocardial infarction (MI), many patients have debilitating symptoms and impaired left ventricular (LV) function highlighting the need for improved post-MI therapies. A promising concept currently under investigation is intramyocardial injection of high-water content, polymeric biomaterial gels (e.g., hydrogels) to modulate myocardial scar formation and LV adverse remodeling. We propose a degradable, bioactive hydrogel that forms a unique microstructure of continuous, parallel capillary-like channels (Capgel). We hypothesize that the innovative architecture and composition of Capgel can serve as a platform for endogenous cell recruitment and drug/cell delivery, therefore facilitating myocardial repair after MI.

Hypoxic ischemic encephalopathy (HIE) affects 2–3 per 1000 full-term neonates. Up to 75% of newborns with severe HIE die or have severe neurological handicaps. Stem cell therapy offers the potential to replace HIE-damaged cells and enhances the autoregeneration process. Our laboratory implanted Multipotent Astrocytic Stem Cells (MASCs) into a neonatal rat model of hypoxia-ischemia (HI) and demonstrated that MASCs move to areas of injury in the cortex and hippocampus. However, only a small proportion of the implanted MASCs differentiated into neurons. MASCs injected into control pups did not move into the cortex or differentiate into neurons. We do not know the mechanism by which the MASCs moved from the site of injection to the injured cortex. We found neurotrophins present after the hypoxic-ischemic milieu and hypothesized that neurotrophins could enhance the migration and differentiation of MASCs. Using a Boyden chamber device, we demonstrated that neurotrophins potentiate the in vitro migration of stem cells. NGF, GDNF, BDNF and NT-3 increased stem cell migration when compared to a chemokinesis control. Also, MASCs had increased differentiation toward neuronal phenotypes when these neurotrophins were added to MASC culture tissue. Due to this finding, we believed neurotrophins could guide migration and differentiation of stem cell transplants after brain injury.

Numerous studies have revealed abnormal cytoarchitectonics in the reeler mouse brain. In the present study, acetylcholinesterase (AChE) histochemistry has revealed a distinctive mosaic within the occipital cortex of the reeler mouse. The mosaic does not appear until after the second postnatal week, perhaps in association with eye opening. AChE staining in the visual cortex of normal littermates does not exhibit a mosaic pattern, but rather, is present within bands or laminae. The AChE mosaic in reeler persists into adulthood. Immunocytochemical staining of the tenascin glycoprotein, an astrocyte-derived extracellular matrix molecule that is concentrated in boundaries around emerging functional patterns in the CNS, reveals a boundary-mosaic pattern in the first postnatal week. Dil axonal tracing in normal versus reeler mice indicates that the thalamocortical projections may also be associated with the AChE mosaic. The observation that a mosaic is unique to the occipital cortex of reeler mice suggests that it may evolve through abnormal cell and molecular interactions in the mutant cortex that normally lead to the development of functional visual representations.

Neural stem cells and neural progenitors (NSC/NPs) hold great promise in neuro-restorative therapy due to their remarkable capacity for self-renewal, plasticity, and ability to integrate into host brain circuitry. Some types of epilepsy would appear to be excellent targets for this type of therapy due to known alterations in local circuitry based on loss or malfunction of specific types of neurons in specific brain structures. Potential sources for NSC/NPs include the embryonic blastocyst, the fetal brain, and adult brain and non-neural tissues. Each of these cell types has potential strengths and weaknesses as candidates for clinical therapeutic agents. This article reviews some of the major types of NSC/NPs and how they have been studied with regard to synaptic integration into host brain circuits. It also reviews how these transplanted cells develop and interact with host brain cells in animal models of epilepsy. The field is still wide open with a number of very promising results but there are also some major challenges that will need to be addressed prior to considering clinical applications for epilepsy.

Malignant glioma is among of the most devastating, and least curable, types of cancer. Since the re-emergence of the cancer stem cell hypothesis, much progress has been made towards elucidating the cellular origin of these tumors. The hypothesis that tumors are hierarchically organized, with a cancer stem cell at the top that shares defining features with somatic stem cells and provides therapeutic refractoriness properties, has put adult stem cells into the limelight as prime suspect for malignant glioma. Much confusion still exists, though, as to the particular cell type and processes that lead to oncogenic transformation. In this review, we will discuss recent developments and novel hypotheses regarding the origin of malignant gliomas, especially glioblastoma. In particular, we argue that glioblastoma is the result of different pathways originating in multiple sources that all ultimately converge in the same disease. Further attention is devoted to potential scenarios leading to transformation of different stem/progenitor cell types of the brain, and the probability and relevance of these scenarios for malignant tumorigenesis. © 2011 Wiley-Liss, Inc.