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The ecosystem of brain tumors is considered immunosuppressed, but our current knowledge may be incomplete. Here we analyzed clinical cell and tissue specimens derived from patients presenting with glioblastoma or nonmalignant intracranial disease to report that the cranial bone (CB) marrow, in juxtaposition to treatment-naive glioblastoma tumors, harbors active lymphoid populations at the time of initial diagnosis. Clinical and anatomical imaging, single-cell molecular and immune cell profiling and quantification of tumor reactivity identified CD8 + T cell clonotypes in the CB that were also found in the tumor. These were characterized by acute and durable antitumor response rooted in the entire T cell developmental spectrum. In contrast to distal bone marrow, the CB niche proximal to the tumor showed increased frequencies of tumor-reactive CD8 + effector types expressing the lymphoid egress marker S1PR1. In line with this, cranial enhancement of CXCR4 radiolabel may serve as a surrogate marker indicating focal association with improved progression-free survival. The data of this study advocate preservation and further exploitation of these cranioencephalic units for the clinical care of glioblastoma., (© 2024. The Author(s).)

Transdifferentiation (TD), a somatic cell reprogramming process that eliminates pluripotent intermediates, creates cells that are ideal for personalized anti-cancer therapy. Here, we provide the first evidence that extracellular vesicles (EVs) from TD-derived induced neural stem cells (Exo-iNSCs) are an efficacious treatment strategy for brain cancer. We found that genetically engineered iNSCs generated EVs loaded with the tumoricidal gene product TRAIL at nearly twice the rate of their parental fibroblasts, and TRAIL produced by iNSCs was naturally loaded into the lumen of EVs and arrayed across their outer membrane (Exo-iNSC-TRAIL). Uptake studies in ex vivo organotypic brain slice cultures showed that Exo-iNSC-TRAIL selectively accumulates within tumor foci, and co-culture assays demonstrated that Exo-iNSC-TRAIL killed metastatic and primary brain cancer cells more effectively than free TRAIL. In an orthotopic mouse model of brain cancer, Exo-iNSC-TRAIL reduced breast-to-brain tumor xenografts by approximately 3000-fold compared to treatment with free TRAIL, with all Exo-iNSC-TRAIL treated animals surviving through 90 days post-treatment. In additional in vivo testing against aggressive U87 and invasive GBM8 glioblastoma tumors, Exo-iNSC-TRAIL also induced a statistically significant increase in survival. These studies establish a novel, easily generated, stable, tumor-targeted EV to efficaciously treat multiple forms of brain cancer., Competing Interests: Declaration of competing interest None., (Published by Elsevier B.V.)

Extracellular vesicles, including exosomes/microvesicles (EMVs), have been described as sensitive biomarkers that represent disease states and response to therapies. In light of recent reports of disease-mirroring EMV molecular signatures, the present study profiled two EMVs from different Parkinson's disease (PD) tissue sources: (a) neural progenitor cells derived from an endogenous adult stem/progenitor cell, called adult human neural progenitor (AHNP) cells, that we found to be pathological when isolated from postmortem PD patients' substantia nigra; and (b) leucine-rich repeat kinase 2 (LRRK2) gene identified patient induced pluripotent stem cells (iPSCs), which were used to isolate EMVs and begin to characterize their cargoes. Initial characterization of EMVs derived from idiopathic patients (AHNPs) and mutant LRRK2 patients showed differences between both phenotypes and when compared with a sibling control in EMV size and release based on Nanosight analysis. Furthermore, molecular profiling disclosed that neurodegenerative-related gene pathways altered in PD can be reversed using gene-editing approaches. In fact, the EMV cargo genes exhibited normal expression patterns after gene editing. This study shows that EMVs have the potential to serve as sensitive biomarkers of disease state in both idiopathic and gene-identified PD patients and that following gene-editing, EMVs reflect a corrected state. This is relevant for both prodromal and symptomatic patient populations where potential responses to therapies can be monitored via non-invasive liquid biopsies and EMV characterizations., (© 2019 Wiley Periodicals, Inc.)

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., (Copyright © 2019 ISDN. Published by Elsevier Ltd. All rights reserved.)

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.

Huntington disease (HD) is an autosomal dominant neurodegenerative disorder caused by expanded CAG repeats in the huntingtin gene ( HTT ). 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 HTT , 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., Competing Interests: The authors declare no conflict of interest., (Copyright © 2018 the Author(s). Published by PNAS.)

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 ., (©2017 American Association for Cancer Research.)

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.

Good health while aging depends upon optimal cellular and organ functioning that contribute to the regenerative ability of the body during the lifespan, especially when injuries and diseases occur. Although diet may help in the maintenance of cellular fitness during periods of stability or modest decline in the regenerative function of an organ, this approach is inadequate in an aged system, in which the ability to maintain homeostasis is further challenged by aging and the ensuing suboptimal functioning of the regenerative unit, tissue-specific stem cells. Focused nutritional approaches can be used as an intervention to reduce decline in the body's regenerative capacity. This article brings together nutrition-associated therapeutic approaches with the fields of aging, immunology, neurodegenerative disease, and cancer to propose ways in which diet and nutrition can work with standard-of-care and integrated medicine to help improve the brain's function as it ages. The field of regenerative medicine has exploded during the past 2 decades as a result of the discovery of stem cells in nearly every organ system of the body, including the brain, where neural stem cells persist in discrete areas throughout life. This fact, and the uncovering of the genetic basis of plasticity in somatic cells and cancer stem cells, open a door to a world where maintenance and regeneration of organ systems maintain health and extend life expectancy beyond its present limits. An area that has received little attention in regenerative medicine is the influence on regulatory mechanisms and therapeutic potential of nutrition. We propose that a strong relation exists between brain regenerative medicine and nutrition and that nutritional intervention at key times of life could be used to not only maintain optimal functioning of regenerative units as humans age but also play a primary role in therapeutic treatments to combat injury and diseases (in particular, those that occur in the latter one-third of the lifespan)., Competing Interests: Author disclosures: The authors are affiliated with a new start-up company, Prana Therapeutics, Inc. They have received no financial compensation in relation to this article., (© 2017 American Society for Nutrition.)

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., Competing Interests: The authors declare no conflict of interests, (©2016 American Association for Cancer Research.)

Diverse cell types have unique transcriptional signatures that are best interrogated at single-cell resolution. Here we describe a novel RNA amplification approach that allows for high fidelity gene profiling of individual cells. This technique significantly diminishes the problem of 3' bias, enabling detection of all regions of transcripts, including the recognition of mRNA with short or completely absent poly(A) tails, identification of noncoding RNAs, and discovery of the full array of splice isoforms from any given gene product. We assess this technique using statistical and bioinformatics analyses of microarray data to establish the limitations of the method. To demonstrate applicability, we profiled individual cells isolated from the mouse subventricular zone (SVZ)-a well-characterized, discrete yet highly heterogeneous neural structure involved in persistent neurogenesis. Importantly, this method revealed multiple splice variants of key germinal zone gene products within individual cells, as well as an unexpected coexpression of several mRNAs considered markers of distinct and separate SVZ cell types. These findings were independently confirmed using RNA-fluorescence in situ hybridization (RNA-FISH), contributing to the utility of this new technology that offers genomic and transcriptomic analysis of small numbers of dynamic and clinically relevant cells.

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.

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., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

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.

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 toward earlier intervention in preclinical AD, it is an open issue 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 preventive measures that can be distributed rapidly to stem the coming wave of AD that will potentially engulf the next generation. We can define regenerative medicine broadly as approaches that use stem cell-based therapies or approaches that seek to modulate inherent neurogenesis. Neurogenesis, although most active during prenatal development, has been shown to continue in several small parts of the brain, including the hippocampus and the subventricular zone, suggesting its potential to reverse cognitive deficits. If AD pathology affects neurogenesis, then it follows that conditions that stimulate endogenous neurogenesis (eg, 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., (Copyright © 2014 Mosby, Inc. All rights reserved.)

Objective: 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., Methods: 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., Results: 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., Conclusions: 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.

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.

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.

Glucocorticoids (GCs) secreted after stress reduce adult hippocampal neurogenesis, a process that has been implicated in cognitive aspects of psychopathology, amongst others. Yet, the exact role of the GC receptor (GR), a key mediator of GC action, in regulating adult neurogenesis is largely unknown. Here, we show that GR knockdown, selectively in newborn cells of the hippocampal neurogenic niche, accelerates their neuronal differentiation and migration. Strikingly, GR knockdown induced ectopic positioning of a subset of the new granule cells, altered their dendritic complexity and increased their number of mature dendritic spines and mossy fiber boutons. Consistent with the increase in synaptic contacts, cells with GR knockdown exhibit increased basal excitability parallel to impaired contextual freezing during fear conditioning. Together, our data demonstrate a key role for the GR in newborn hippocampal cells in mediating their synaptic connectivity and structural as well as functional integration into mature hippocampal circuits involved in fear memory consolidation.

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., (©2013 AACR.)

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., (© 2013 The Authors. Published by John Wiley and Sons, Ltd on behalf of EMBO.)

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., (Copyright © 2012 Elsevier Inc. All rights reserved.)

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.

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., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The success of cellular therapies for Parkinson's disease (PD) will depend not only on a conducive growth environment in vivo, but also on the ex vivo amplification and targeted neural differentiation of stem/progenitor cells. Here, we demonstrate the in vitro proliferative and differentiation potential of stem/progenitor cells, adult human neural progenitor cells ("AHNPs") isolated from idiopathic PD postmortem tissue samples and, to a lesser extent, discarded deep brain stimulation electrodes. We demonstrate that these AHNPs can be isolated from numerous structures (e.g. substantia nigra, "SN") and are able to differentiate into both glia and neurons, but only under particular growth conditions including co-culturing with embryonic stem cell-derived neural precursors ("ESNPs"); this suggests that PD multipotent neural stem/progenitor cells do reside within the SN and other areas, but by themselves appear to lack key factors required for neuronal differentiation. AHNPs engraft following ex vivo expansion and transplantation into the rodent brain, demonstrating their regenerative potential. Our data demonstrate the presence and capacity of endogenous stem/progenitor cells in the PD brain., (Copyright © 2012 Elsevier B.V. All rights reserved.)

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.

Transplantation of neural stems cells (NSCs) could be a useful means to deliver biologic therapeutics for late-stage Alzheimer's disease (AD). In this study, we conducted a small preclinical investigation of whether NSCs could be modified to express metalloproteinase 9 (MMP9), a secreted protease reported to degrade aggregated Aβ peptides that are the major constituents of the senile plaques. Our findings illuminated three issues with using NSCs as delivery vehicles for this particular application. First, transplanted NSCs generally failed to migrate to amyloid plaques, instead tending to colonize white matter tracts. Second, the final destination of these cells was highly influenced by how they were delivered. We found that our injection methods led to cells largely distributing to white matter tracts, which are anisotropic conduits for fluids that facilitate rapid distribution within the CNS. Third, with regard to MMP9 as a therapeutic to remove senile plaques, we observed high concentrations of endogenous metalloproteinases around amyloid plaques in the mouse models used for these preclinical tests with no evidence that the NSC-delivered enzymes elevated these activities or had any impact. Interestingly, MMP9-expressing NSCs formed substantially larger grafts. Overall, we observed long-term survival of NSCs in the brains of mice with high amyloid burden. Therefore, we conclude that such cells may have potential in therapeutic applications in AD but improved targeting of these cells to disease-specific lesions may be required to enhance efficacy.

Cells with certain attributes of very immature astroglial cells and their radial precursors can act as stem and/or progenitor cells during developmental and persistent neurogenesis. Neural stem/progenitor cells both express and are affected by a variety of developmentally regulated macromolecules and growth factors, and such signaling or recognition molecules are being uncovered through extensive genomic and proteomic studies, as well as tested using in vitro/in vivo cell growth bioassays. Glycosylated molecules are appreciated as distinct signaling molecules during morphogenesis in a variety of tissues and organs, with glycoconjugates (glycoproteins, glycolipids, and glycosaminoglycans) serving as mediators for the interactions of cells with each other and their substrates, to confer growth and differentiation cues to precursor cells in search of identity. Neurogenic astrocytes and associated glycoconjugates, especially extracellular matrix molecules, are discussed in the context of neurogenesis and stem/progenitor cell growth, fate choice, and differentiation.

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., (Copyright © 2011 Wiley-Liss, Inc.)

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., (Copyright © 2011 Elsevier Inc. All rights reserved.)

In severe hypoxic-ischemic brain injury, cellular components such as neurons and astrocytes are injured or destroyed along with the supporting extracellular matrix. This presents a challenge to the field of regenerative medicine since the lack of extracellular matrix and supporting structures makes the transplant milieu inhospitable to the transplanted cells. A potential solution to this problem is the use of a biomaterial to provide the extracellular components needed to keep cells localized in cystic brain regions, allowing the cells to form connections and repair lost brain tissue. Ideally, this biomaterial would be combined with stem cells, which have been proven to have therapeutic potentials, and could be delivered via an injection. To study this approach, we derived a hydrogel biomaterial tissue scaffold from oligomeric gelatin and copper-capillary alginate gel (GCCAG). We then demonstrated that our multipotent astrocytic stem cells (MASCs) could be maintained in GCCAG scaffolds for up to 2 weeks in vitro and that the cells retained their multipotency. We next performed a pilot transplant study in which GCCAG was mixed with MASCs and injected into the brain of a neonatal rat pup. After a week in vivo, our results showed that: the GCCAG biomaterial did not cause a significant reactive gliosis; viable cells were retained within the injected scaffolds; and some delivered cells migrated into the surrounding brain tissue. Therefore, GCCAG tissue scaffolds are a promising, novel injectable system for transplantation of stem cells to the brain.

Large-scale proliferation and multi-lineage differentiation capabilities make neural stem cells (NSCs) a promising renewable source of cells for therapeutic applications. However, the practical application for neuronal cell replacement is limited by heterogeneity of NSC progeny, relatively low yield of neurons, predominance of astrocytes, poor survival of donor cells following transplantation and the potential for uncontrolled proliferation of precursor cells. To address these impediments, we have developed a method for the generation of highly enriched immature neurons from murine NSC progeny. Adaptation of the standard differentiation procedure in concert with flow cytometry selection, using scattered light and positive fluorescent light selection based on cell surface antibody binding, provided a near pure (97%) immature neuron population. Using the purified neurons, we screened a panel of growth factors and found that bone morphogenetic protein-4 (BMP-4) demonstrated a strong survival effect on the cells in vitro, and enhanced their functional maturity. This effect was maintained following transplantation into the adult mouse striatum where we observed a 2-fold increase in the survival of the implanted cells and a 3-fold increase in NeuN expression. Additionally, based on the neural-colony forming cell assay (N-CFCA), we noted a 64 fold reduction of the bona fide NSC frequency in neuronal cell population and that implanted donor cells showed no signs of excessive or uncontrolled proliferation. The ability to provide defined neural cell populations from renewable sources such as NSC may find application for cell replacement therapies in the central nervous system.

The hippocampal dentate gyrus maintains its capacity to generate new neurons throughout life. In animal models, hippocampal neurogenesis is increased by cognitive tasks, and experimental ablation of neurogenesis disrupts specific modalities of learning and memory. In humans, the impact of neurogenesis on cognition remains unclear. Here, we assessed the neurogenic potential in the human hippocampal dentate gyrus by isolating adult human neural stem cells from 23 surgical en bloc hippocampus resections. After proliferation of the progenitor cell pool in vitro we identified two distinct patterns. Adult human neural stem cells with a high proliferation capacity were obtained in 11 patients. Most of the cells in the high proliferation capacity cultures were capable of neuronal differentiation (53 ± 13% of in vitro cell population). A low proliferation capacity was observed in 12 specimens, and only few cells differentiated into neurons (4 ± 2%). This was reflected by reduced numbers of proliferating cells in vivo as well as granule cells immunoreactive for doublecortin, brain-derived neurotrophic factor and cyclin-dependent kinase 5 in the low proliferation capacity group. High and low proliferation capacity groups differed dramatically in declarative memory tasks. Patients with high proliferation capacity stem cells had a normal memory performance prior to epilepsy surgery, while patients with low proliferation capacity stem cells showed severe learning and memory impairment. Histopathological examination revealed a highly significant correlation between granule cell loss in the dentate gyrus and the same patient's regenerative capacity in vitro (r = 0.813; P < 0.001; linear regression: R²(adjusted) = 0.635), as well as the same patient's ability to store and recall new memories (r = 0.966; P = 0.001; linear regression: R²(adjusted) = 0.9). Our results suggest that encoding new memories is related to the regenerative capacity of the hippocampus in the human brain.

Residual tumor cells remain beyond the margins of every glioblastoma (GBM) resection. Their resistance to postsurgical therapy is considered a major driving force of mortality, but their biology remains largely uncharacterized. In this study, residual tumor cells were derived via experimental biopsy of the resection margin after standard neurosurgery for direct comparison with samples from the routinely resected tumor tissue. In vitro analysis of proliferation, invasion, stem cell qualities, GBM-typical antigens, genotypes, and in vitro drug and irradiation challenge studies revealed these cells as unique entities. Our findings suggest a need for characterization of residual tumor cells to optimize diagnosis and treatment of GBM.

Purpose: We identified a discrete population of stem cell-like tumor cells expressing 5 essential transcription factors required to reprogram pluripotency in prostate tumor cell lines and primary prostate cancer tissue., Materials and Methods: DU145 and PC3 human prostate cancer cell lines (ATCC), tumor tissue from patients with prostate cancer and normal prostate tissue were evaluated for the reprogramming factors OCT3/4 (Cell Signaling Technology), SOX2, Klf4 (Santa Cruz Biotechnology, Santa Cruz, California), Nanog (BioLegend) and c-Myc (Cell Signaling) by semiquantitative reverse transcriptase-polymerase chain reaction, histological and immunohistochemical analysis. Stem cell-like tumor cells were enriched by flow cytometric cell sorting using E-cadherin (R&D Systems) as a surface marker, and soft agar, spheroid and tumorigenicity assays to confirm cancer stem cell-like characteristics., Results: mRNA expression of transcription factors OCT3/4 and SOX2 highly correlated in primary prostate tumor tissue samples. The number of OCT3/4 or SOX2 expressing cells was significantly increased in prostate cancer tissue compared to that in normal prostate or benign prostate hyperplasia tissue (p <0.05). When isolated from the DU145 and PC3 prostate cancer cell lines by flow cytometry, stem cell-like tumor cells expressing high OCT3/4 and SOX2 levels showed high tumorigenicity in immunodeficient mice. In vivo growth of the parental DU145 and PC3 prostate cancer cell lines was inhibited by short hairpin RNA knockdown of OCT3/4 or SOX2., Conclusions: Data suggest that prostate tumor cells expressing pluripotent stem cell transcription factors are highly tumorigenic. Identifying such cells and their importance in prostate cancer growth could provide opportunities for novel targeting strategies for prostate cancer therapy., (2010 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.)

Patients with chronic ulcerative colitis are at increased risk of developing colorectal cancer. Although current hypotheses suggest that sporadic colorectal cancer is due to inability to control cancer stem cells, the cancer stem cell hypothesis has not yet been validated in colitis-associated cancer. Furthermore, the identification of the colitis to cancer transition is challenging. We recently showed that epithelial cells with the increased expression of aldehyde dehydrogenase in sporadic colon cancer correlate closely with tumor-initiating ability. We sought to determine whether ALDH can be used as a marker to isolate tumor-initiating populations from patients with chronic ulcerative colitis. We used fluorescence-activated cell sorting to identify precursor colon cancer stem cells from colitis patients and report both their transition to cancerous stem cells in xenografting studies as well as their ability to generate spheres in vitro. Similar to sporadic colon cancer, these colitis-derived tumors were capable of propagation as sphere cultures. However, unlike the origins of sporadic colon cancer, the primary colitic tissues did not express any histologic evidence of dysplasia. To elucidate a potential mechanism for our findings, we compared the stroma of these different environments and determined that at least one paracrine factor is up-regulated in the inflammatory and malignant stroma compared with resting, normal stroma. These data link colitis and cancer identifying potential tumor-initiating cells from colitic patients, suggesting that sphere and/or xenograft formation will be useful to survey colitic patients at risk of developing cancer.

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 approximately 24% of the OS521Oct-4p cells were capable of activating the transgenic Oct-4 promoter; yet, xenograft tumors generated in NOD/SCID mice contained approximately 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 <300 cells, and formed metastases in the lung. Clonal populations derived from a single Oct-4/GFP(+) cell were capable of forming tumors heterogeneous for Oct-4/GFP expression. These data are consistent with the cancer stem cell model of tumorigenesis in osteosarcoma and implicate a functional link between the capacity to activate an exogenous Oct-4 promoter and tumor formation. This osteosarcoma tumor-initiating cell appears highly prolific and constitutes a majority of the cell population in a primary xenograft tumor, which may provide a biological basis for the particular virulence of this type of cancer.

Numerous studies have explored the potential of different stem and progenitor cells to replace at-risk neuronal populations in a variety of neurodegenerative disease models. This study presents data from a side-by-side approach of engrafting two different stem/progenitor cell populations within the postnatal cerebellum of the weaver neurological mutant mouse--cerebellar-derived multipotent astrocytic stem cells and embryonic stem cell-derived neural precursors--for comparative analysis. We show here that both donor populations survive, migrate, and appear to initiate differentiation into neurons within the granuloprival host environment. Neither of these disparate stem/progenitor cell populations adopted significant region-specific identities, despite earlier studies that suggested the potential of these cells to respond to in vivo cues when placed in a permissive/instructive milieu. However, data presented here suggest that molecular and cellular deficits present within weaver homozygous or heterozygous brains may promote a slightly more positive donor cell response toward acquisition of a neuronal phenotype. Hence, it is likely that a fine balance exists between a compromised host environment that is amenable to cell replacement and that of a degenerating cellular milieu where it is perhaps too deleterious to support extensive neuronal differentiation and functional cellular integration. These findings join a growing list of studies that show successful cell replacement depends largely on the interplay between the potentiality of the donor cells and the specific pathological conditions of the recipient environment, and that emergent therapies for neurological disorders involving the use of neural stem cells still require refinement.

In addition to radial glial cells of neurohistogenesis, immature astrocytes with stem-cell-like properties cordon off emerging functional patterns in the developing brain. Astrocytes also can be stem cells during adult neurogenesis, and a proposed potency of injury-associated reactive astrocytes has recently been substantiated. Astrocytic cells might additionally be involved in cancer stem cell-associated gliomagenesis. Thus, there are distinguishing roles for stem-cell-like astrocytes during brain development, in neurogenic niches in the adult, during attempted reactive neurogenesis after brain injury or disease and during brain tumorigenesis.

An increasing body of evidence suggests that astrocytic gliomas of the central nervous system may be derived from gliotypic neural stem cells. To date, the study of these tumors, particularly the identification of originating cellular population(s), has been frustrated by technical difficulties in accessing the native niche of stem cells. To identify any hallmark signs of cancer in neural stem cells or their progeny, we cultured subventricular zone-derived tissue in a unique in vitro model that temporally and phenotypically recapitulates adult neurogenesis. Contrary to some reports, we found undifferentiated neural stem cells possess few characteristics, suggesting prototumorigenic potential. However, when induced to differentiate, neural stem cells give rise to intermediate progenitors that transiently exhibit multiple glioma characteristics, including aneuploidy, loss of growth-contact inhibition, alterations in cell cycle, and growth factor insensitivity. Further examination of progenitor populations revealed a subset of cells defined by the aberrant expression of (the pathological glioma marker) class III beta-tubulin that exhibit intrinsic parental properties of gliomas, including multilineage differentiation and continued proliferation in the absence of a complex cellular regulatory environment. As tumorigenic characteristics in progenitor cells normally disappear with the generation of mature progeny, this suggests that developmentally intermediate progenitor cells, rather than neural stem cells, may be the origin of so-called "stem cell-derived" tumors.

Bromodeoxyuridine (BrdU) is a halogenated pyrimidine that incorporates into newly synthesized DNA during the S phase. BrdU is used ubiquitously in cell birthdating studies and as a means of measuring the proliferative index of various cell populations. In the absence of secondary stressors, BrdU is thought to incorporate relatively benignly into replicating DNA chains. However, we report here that a single, low-dose pulse of BrdU exerts a profound and sustained antiproliferative effect in cultured murine stem and progenitor cells. This is accompanied by altered terminal differentiation, cell morphology, and protein expression consistent with the induction of senescence. There is no evidence of a significant increase in spontaneous cell death; however, cells are rendered resistant to chemically induced apoptosis. Finally, we show that a brief in vivo BrdU regimen reduces the proliferative potential of subsequently isolated subependymal zone neurosphere-forming cells. We conclude, therefore, that BrdU treatment induces a senescence pathway that causes a progressive decline in the replication of rapidly dividing stem/progenitor cells, suggesting a novel and uncharacterized effect of BrdU. This finding is significant in that BrdU-incorporating neural stem/progenitor cells and their progeny should not be expected to behave normally with respect to proliferative potential and downstream functional parameters. This effect highlights the need for caution when results based on long-term BrdU tracking over multiple rounds of replication are interpreted. Conversely, the reliable induction of senescence in stem/progenitor cells in vitro and in vivo may yield a novel platform for molecular studies designed to address multiple aspects of aging and neurogenesis.

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 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., (Copyright 2008 Wiley-Liss, Inc.)

Generation of new neurons in the adult brain, a process that is likely to be essential for learning, memory, and mood regulation, is impaired by radiation. Therefore, radiation exposure might have not only such previously expected consequences as increased probability of developing cancer, but might also impair cognitive function and emotional stability. Radiation exposure is encountered in settings ranging from cancer therapy to space travel; evaluating the neurogenic risks of radiation requires identifying the at-risk populations of stem and progenitor cells in the adult brain. Here we have used a novel reporter mouse line to find that early neural progenitors are selectively affected by conditions simulating the space radiation environment. This is reflected both in a decrease in the number of these progenitors in the neurogenic regions and in an increase in the number of dying cells in these regions. Unexpectedly, we found that quiescent neural stem cells, rather than their rapidly dividing progeny, are most sensitive to radiation. Since these stem cells are responsible for adult neurogenesis, their death would have a profound impact on the production of new neurons in the irradiated adult brain. Our finding raises an important concern about cognitive and emotional risks associated with radiation exposure.

The relatively recent discovery of persistent adult neurogenesis has led to the experimental isolation and characterization of central nervous system neural stem cell populations. Protocols for in vitro analysis and expansion of neural stem cells are crucial for understanding their properties and defining characteristics. The methods described here allow for cell and molecular analysis of individual clones of cells--neurospheres--derived from neural stem/progenitor cells. Neurospheres can be cultivated from a variety of normal, genetically altered, or pathological tissue specimens, even with protracted postmortem intervals, for studies of mechanisms underlying neurogenesis, cell fate decisions, and cell differentiation. Neurosphere-forming cells hold great promise for the development of cell and molecular therapeutics for a variety of neurological diseases.