Neurosphere

About: Neurosphere is a research topic. Over the lifetime, 5145 publications have been published within this topic receiving 321088 citations.

Hypoxia Increases the Expression of Stem-Cell Markers and Promotes Clonogenicity in Glioblastoma Neurospheres

Abstract: Hypoxia promotes the expansion of non-neoplastic stem and precursor cell populations in the normal brain, and is common in malignant brain tumors. We examined the effects of hypoxia on stem-like cells in glioblastoma (GBM). When GBM-derived neurosphere cultures are grown in 1% oxygen, hypoxia-inducible factor 1α (HIF1α) protein levels increase dramatically, and mRNA encoding other hypoxic response genes, such as those encoding hypoxia-inducible gene-2, lysyl oxidase, and vascular endothelial growth factor, are induced over 10-fold. Hypoxia increases the stem-like side population over fivefold, and the percentage of cells expressing CD133 threefold or more. Notch pathway ligands and targets are also induced. The rise in the stem-like fraction in GBM following hypoxia is paralleled by a twofold increase in clonogenicity. We believe HIF1α plays a causal role in these changes, as when oxygen-stable HIF1α is expressed in normoxic glioma cells CD133 is induced. We used digoxin, which has been shown to lower HIF protein levels in vitro and in vivo, to inhibit the hypoxic response. Digoxin suppressed HIF1α protein expression, HIF1α downstream targets, and slowed tumor growth in vivo. In addition, pretreatment with digoxin reduced GBM flank xenograft engraftment of hypoxic GBM cells, and daily intraperitoneal injections of digoxin were able to significantly inhibit the growth of established subcutaneous glioblastoma xenografts, and suppressed expression of vascular endothelial growth factor.

N-CoR controls differentiation of neural stem cells into astrocytes.

Abstract: Understanding the gene programmes that regulate maintenance and differentiation of neural stem cells is a central question in stem cell biology. Virtually all neural stem cells maintain an undifferentiated state and the capacity to self-renew in response to fibroblast growth factor-2 (FGF2)1,2,3,4,5. Here we report that a repressor of transcription, the nuclear receptor co-repressor (N-CoR), is a principal regulator in neural stem cells, as FGF2-treated embryonic cortical progenitors from N-CoR gene-disrupted mice display impaired self-renewal and spontaneous differentiation into astroglia-like cells. Stimulation of wild-type neural stem cells with ciliary neurotrophic factor (CNTF), a differentiation-inducing cytokine3, results in phosphatidylinositol-3-OH kinase/Akt1 kinase-dependent phosphorylation of N-CoR, and causes a temporally correlated redistribution of N-CoR to the cytoplasm. We find that this is a critical strategy for cytokine-induced astroglia differentiation and lineage-characteristic gene expression. Recruitment of protein phosphatase-1 to a specific binding site on N-CoR exerts a reciprocal effect on the cellular localization of N-CoR. We propose that repression by N-CoR, modulated by opposing enzymatic activities, is a critical mechanism in neural stem cells that underlies the inhibition of glial differentiation.

A detailed mammosphere assay protocol for the quantification of breast stem cell activity.

Abstract: Since the discovery that neural tissue contains a population of stem cells that form neurospheres in vitro, sphere-forming assays have been adapted for use with a number of different tissue types for the quantification of stem cell activity and self-renewal. One tissue type widely used for stem cell investigations is mammary tissue, and the mammosphere assay has been used in both normal tissue and cancer. Although it is a relatively simple assay to learn, it can be difficult to master. There are methodological and analytical aspects to the assay which require careful consideration when interpreting the results. We describe here a detailed mammosphere assay protocol for the assessment of stem cell activity and self-renewal, and discuss how data generated by the assay can be analysed and interpreted.

Human Glioblastoma–Derived Cancer Stem Cells: Establishment of Invasive Glioma Models and Treatment with Oncolytic Herpes Simplex Virus Vectors

Abstract: Glioblastoma, the most malignant type of primary brain tumor, is one of the solid cancers where cancer stem cells have been isolated, and studies have suggested resistance of those cells to chemotherapy and radiotherapy. Here, we report the establishment of CSC-enriched cultures derived from human glioblastoma specimens. They grew as neurospheres in serum-free medium with epidermal growth factor and fibroblast growth factor 2, varied in the level of CD133 expression and very efficiently formed highly invasive and/or vascular tumors upon intracerebral implantation into immunodeficient mice. As a novel therapeutic strategy for glioblastoma-derived cancer stem–like cells (GBM-SC), we have tested oncolytic herpes simplex virus (oHSV) vectors. We show that although ICP6 (UL39)–deleted mutants kill GBM-SCs as efficiently as wild-type HSV, the deletion of γ34.5 significantly attenuated the vectors due to poor replication. However, this was significantly reversed by the additional deletion of α47. Infection with oHSV G47Δ (ICP6−, γ34.5−, α47−) not only killed GBM-SCs but also inhibited their self-renewal as evidenced by the inability of viable cells to form secondary tumor spheres. Importantly, despite the highly invasive nature of the intracerebral tumors generated by GBM-SCs, intratumoral injection of G47Δ significantly prolonged survival. These results for the first time show the efficacy of oHSV against human GBM-SCs, and correlate this cytotoxic property with specific oHSV mutations. This is important for designing new oHSV vectors and clinical trials. Moreover, the new glioma models described in this study provide powerful tools for testing experimental therapeutics and studying invasion and angiogenesis. [Cancer Res 2009;69(8):3472–81]

Cardiac neural crest cells contribute to the dormant multipotent stem cell in the mammalian heart

Abstract: Arodent cardiac side population cell fraction formed clonal spheroids in serum-free medium, which expressed nestin, Musashi-1, and multi-drug resistance transporter gene 1, markers of undifferentiated neural precursor cells. These markers were lost following differentiation, and were replaced by the expression of neuron-, glial-, smooth muscle cell–, or cardiomyocyte-specific proteins. Cardiosphere-derived cells transplanted into chick embryos migrated to the truncus arteriosus and cardiac outflow tract and contributed to dorsal root ganglia, spinal nerves, and aortic smooth muscle cells. Lineage studies using double transgenic mice encoding protein 0–Cre/Floxed-EGFP revealed undifferentiated and differentiated neural crest-derived cells in the fetal myocardium. Undifferentiated cells expressed GATA-binding protein 4 and nestin, but not actinin, whereas the differentiated cells were identified as cardiomyocytes. These results suggest that cardiac neural crest-derived cells migrate into the heart, remain there as dormant multipotent stem cells—and under the right conditions—differentiate into cardiomyocytes and typical neural crest-derived cells, including neurons, glia, and smooth muscle.