Showing papers on "Neurosphere published in 2000"
TL;DR: Before the full potential of neural stem cells can be realized, the authors need to learn what controls their proliferation, as well as the various pathways of differentiation available to their daughter cells.
Abstract: Neural stem cells exist not only in the developing mammalian nervous system but also in the adult nervous system of all mammalian organisms, including humans. Neural stem cells can also be derived from more primitive embryonic stem cells. The location of the adult stem cells and the brain regions to which their progeny migrate in order to differentiate remain unresolved, although the number of viable locations is limited in the adult. The mechanisms that regulate endogenous stem cells are poorly understood. Potential uses of stem cells in repair include transplantation to repair missing cells and the activation of endogenous cells to provide "self-repair. " Before the full potential of neural stem cells can be realized, we need to learn what controls their proliferation, as well as the various pathways of differentiation available to their daughter cells.
4,608 citations
TL;DR: Upon transplantation into brains of immunodeficient neonatal mice, the sorted/expanded hCNS-SC showed potent engraftment, proliferation, migration, and neural differentiation.
Abstract: Stem cells, which are clonogenic cells with self-renewal and multilineage differentiation properties, have the potential to replace or repair damaged tissue. We have directly isolated clonogenic human central nervous system stem cells (hCNS-SC) from fresh human fetal brain tissue, using antibodies to cell surface markers and fluorescence-activated cell sorting. These hCNS-SC are phenotypically 5F3 (CD133)+, 5E12+, CD34−, CD45−, and CD24−/lo. Single CD133+ CD34− CD45− sorted cells initiated neurosphere cultures, and the progeny of clonogenic cells could differentiate into both neurons and glial cells. Single cells from neurosphere cultures initiated from CD133+ CD34− CD45− cells were again replated as single cells and were able to reestablish neurosphere cultures, demonstrating the self-renewal potential of this highly enriched population. Upon transplantation into brains of immunodeficient neonatal mice, the sorted/expanded hCNS-SC showed potent engraftment, proliferation, migration, and neural differentiation.
1,919 citations
TL;DR: It is shown that neural stem cells from the adult mouse brain can contribute to the formation of chimeric chick and mouse embryos and give rise to cells of all germ layers, demonstrating that an adult neural stem cell has a very broad developmental capacity.
Abstract: The differentiation potential of stem cells in tissues of the adult has been thought to be limited to cell lineages present in the organ from which they were derived, but there is evidence that some stem cells may have a broader differentiation repertoire. We show here that neural stem cells from the adult mouse brain can contribute to the formation of chimeric chick and mouse embryos and give rise to cells of all germ layers. This demonstrates that an adult neural stem cell has a very broad developmental capacity and may potentially be used to generate a variety of cell types for transplantation in different diseases.
1,118 citations
TL;DR: It is shown here that certain extracellular signals can induce oligodendrocyte precursor cells to revert to multipotential neural stem cells, which can self-renew and give rise to neurons and astrocytes, as well as to oligodends, which have greater developmental potential than previously thought.
Abstract: During animal development, cells become progressively more restricted in the cell types to which they can give rise. In the central nervous system (CNS), for example, multipotential stem cells produce various kinds of specified precursors that divide a limited number of times before they terminally differentiate into either neurons or glial cells. We show here that certain extracellular signals can induce oligodendrocyte precursor cells to revert to multipotential neural stem cells, which can self-renew and give rise to neurons and astrocytes, as well as to oligodendrocytes. Thus, these precursor cells have greater developmental potential than previously thought.
882 citations
TL;DR: It is suggested that Notch1 promotes radial glial identity during embryogenesis, and that radial glia may be lineally related to stem cells in the adult nervous system.
764 citations
TL;DR: It is concluded that environmental factors, simulated by certain in vitro conditions, transiently confer NSC-like attributes on astrocytes during a critical period in CNS development.
Abstract: 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.
737 citations
TL;DR: Musashi1 was localized to the perikarya of CNS stem-like cells and non-oligodendroglial progenitor cells without shifting to cell processes or endfeet, and is therefore advantageous for identifying each cell and counting cells in situ.
Abstract: In situ detection of neural progenitor cells including stem-like cells is essential for studying the basic mechanisms of the generation of cellular diversity in the CNS, upon which therapeutic treatme
531 citations
TL;DR: It is shown that acutely isolated and clonally derived neural stem cells from mice and humans could produce skeletal myotubes in vitro and in vivo, the latter following transplantation into adult animals and a community effect between neural cells may override such myogenic induction.
Abstract: Distinct cell lineages established early in development are usually maintained throughout adulthood. Thus, adult stem cells have been thought to generate differentiated cells specific to the tissue in which they reside. This view has been challenged; for example, neural stem cells can generate cells that normally originate from a different germ layer. Here we show that acutely isolated and clonally derived neural stem cells from mice and humans could produce skeletal myotubes in vitro and in vivo, the latter following transplantation into adult animals. Myogenic conversion in vitro required direct exposure to myoblasts, and was blocked if neural cells were clustered. Thus, a community effect between neural cells may override such myogenic induction. We conclude that neural stem cells, which generate neurons, glia and blood cells, can also produce skeletal muscle cells, and can undergo various patterns of differentiation depending on exposure to appropriate epigenetic signals in mature tissues.
497 citations
TL;DR: It is demonstrated that hJagged-1 represents a novel growth factor of human stem cells, thereby providing an opportunity for the clinical utility of Notch ligands in the expansion of primitive cells capable of hematopoietic reconstitution.
Abstract: The Notch ligand, Jagged-1, plays an essential role in tissue formation during embryonic development of primitive organisms. However, little is known regarding the role of Jagged-1 in the regulation of tissue-specific stem cells or its function in humans. Here, we show that uncommitted human hematopoietic cells and cells that comprise the putative blood stem cell microenvironment express Jagged-1 and the Notch receptors. Addition of a soluble form of human Jagged-1 to cultures of purified primitive human blood cells had modest effects in augmenting cytokine-induced proliferation of progenitors. However, intravenous transplantation of cultured cells into immunodeficient mice revealed that human (h)Jagged-1 induces the survival and expansion of human stem cells capable of pluripotent repopulating capacity. Our findings demonstrate that hJagged-1 represents a novel growth factor of human stem cells, thereby providing an opportunity for the clinical utility of Notch ligands in the expansion of primitive cells capable of hematopoietic reconstitution.
464 citations
TL;DR: Retrovirus-mediated transfer of the gene for interleukin-4 is an effective treatment for rat brain glioblastomas and a new approach for gene therapy of brain tumors, based on the grafting of neural stem cells producing therapeutic molecules is supported.
Abstract: Glioblastomas, the most frequent and malignant of primary brain tumors, have a very poor prognosis. Gene therapy of glioblastomas is limited by the short survival of viral vectors and by their difficulty in reaching glioblastoma cells infiltrating the brain parenchyma. Neural stem/progenitor cells can be engineered to produce therapeutic molecules and have the potential to overcome these limitations because they may travel along the white matter, like neoplastic cells, and engraft stably into the brain. Retrovirus-mediated transfer of the gene for interleukin-4 is an effective treatment for rat brain glioblastomas. Here, we transferred the gene for interleukin-4 into C57BL6J mouse primary neural progenitor cells and injected those cells into established syngeneic brain glioblastomas. This led to the survival of most tumor-bearing mice. We obtained similar results by implanting immortalized neural progenitor cells derived from Sprague-Dawley rats into C6 glioblastomas. We also documented by magnetic resonance imaging the progressive disappearance of large tumors, and detected 5-bromodeoxyuridine-labeled progenitor cells several weeks after the injection. These findings support a new approach for gene therapy of brain tumors, based on the grafting of neural stem cells producing therapeutic molecules.
461 citations
TL;DR: It is proposed that high Delta1 expression by epidermal stem cells has three effects: a protective effect on stem cells by blocking Notch signalling; enhanced cohesiveness of stem-cell clusters, which may discourage intermingling with neighbouring cells; and signalling to cells at the edges of the clusters to differentiate.
Patent•
10 Mar 2000TL;DR: In this paper, a lipo-derived stem cell and lattice were used to facilitate the growth and differentiation of cells, whether in vivo or in vitro, into anlagen or even mature tissues or structures.
Abstract: The present invention provides adipose-derived stem cells and lattices. In one aspect, the present invention provides a lipo-derived stem cell substantially free of adipocytes and red blood cells and clonal populations of connective tissue stem cells. The cells can be employed, alone or within biologically-compatible compositions, to generate differentiated tissues and structures, both in vivo and in vitro. Additionally, the cells can be expanded and cultured to produce hormones and to provide conditioned culture media for supporting the growth and expansion of other cell populations. In another aspect, the present invention provides a lipo-derived lattice substantially devoid of cells, which includes extracellular matrix material from adipose tissue. The lattice can be used as a substrate to facilitate the growth and differentiation of cells, whether in vivo or in vitro, into anlagen or even mature tissues or structures.
TL;DR: It is demonstrated that murine dorsal keratinocytes characterized by their high levels of alpha(6) integrin and low to undetectable expression of the transferrin receptor (CD71) termed alpha(bri)CD71(dim) cells, are enriched for epithelial stem cells.
Abstract: The identification and physical isolation of epithelial stem cells is critical to our understanding of their growth regulation during homeostasis, wound healing, and carcinogenesis. These stem cells remain poorly characterized because of the absence of specific molecular markers that permit us to distinguish them from their progeny, the transit amplifying (TA) cells, which have a more restricted proliferative potential. Cell kinetic analyses have permitted the identification of murine keratinocyte stem cells (KSCs) as slowly cycling cells that retain [3H]thymidine ([3H]Tdr) label, termed label-retaining cells (LRCs), whereas TA cells are visualized as rapidly cycling cells after a single pulse of [3H]Tdr, termed pulse-labeled cells (PLCs). Here, we report on the successful separation of KSCs from TA cells through the combined use of in vivo cell kinetic analysis and fluorescence-activated cell sorting. Specifically, we demonstrate that murine dorsal keratinocytes characterized by their high levels of α6 integrin and low to undetectable expression of the transferrin receptor (CD71) termed α6briCD71dim cells, are enriched for epithelial stem cells because they represent a minor (≈8%) and quiescent subpopulation of small blast-like cells, with a high nuclear:cytoplasmic ratio, containing ≈70% of label-retaining cells, the latter being a well documented characteristic of stem cells. Conversely, TA cells could be enriched in a phenotypically distinct subpopulation termed α6briCD71bri, representing the majority (≈60%) of basal keratinocytes that are actively cycling, and importantly contain ≈70% of [3H]Tdr pulse-labeled cells. Importantly, immunostaining of dorsal skin revealed the presence of CD71dim cells in the hair follicle bulge region, a well documented location for KSCs.
TL;DR: It is demonstrated that, both in vitro and in vivo, neural stem cells undergoing cell division are immunopositive for cystatin C, and it is proposed that the process of neurogenesis is controlled by the cooperation between trophic factors and autocrine/paracrine cofactors, of which CCg is a prototype.
TL;DR: Evidence is found that neural cell fate is specified in utero, before the generation of the primitive streak or Hensen's node, and FGF signalling appears to be required for the repression of Bmp expression and for the acquisition of neural fate.
TL;DR: Hes1 is important for maintaining the self-renewing ability of progenitors and for repressing the commitment of multipotent progenitor cells to a neuronal fate, which is critical for the correct number of neurons to be produced and for the establishment of normal neuronal function.
Abstract: Hes1 is one of the basic helix-loop-helix transcription factors that regulate mammalian CNS development, and its loss- and gain-of-function phenotypes indicate that it negatively regulates neuronal differentiation.
Here we report that Hes1−/− mice expressed both early (TuJ1 and Hu) and late (MAP2 and Neurofilament) neuronal markers prematurely, and that there were approximately twice the normal number of neurons in the Hes1−/− brain during early neural development. However, immunochemical analyses of sections and dissociated cells using neural progenitor markers, including nestin, failed to detect any changes in Hes1−/− progenitor population. Therefore, further characterization of neural progenitor cells that discriminated between multipotent and monopotent cells was performed using two culture methods, low-density culture, and a neurosphere assay. We demonstrate that the self-renewal activity of multipotent progenitor cells was reduced in the Hes1−/− brain, and that their subsequent commitment to the neuronal lineage was accelerated. The Hes1−/− neuronal progenitor cells were functionally abnormal, in that they divided, on average, only once, and then generated two neurons, (instead of one progenitor cell and one neuron), whereas wild-type progenitor cells divided more. In addition, some Hes1−/− progenitors followed an apoptotic fate. The overproduction of neurons in the early Hes1−/− brains may reflect this premature and immediate generation of neurons as well as a net increase in the number of neuronal progenitor cells.
Taken together, we conclude that Hes1 is important for maintaining the self-renewing ability of progenitors and for repressing the commitment of multipotent progenitor cells to a neuronal fate, which is critical for the correct number of neurons to be produced and for the establishment of normal neuronal function.
TL;DR: V-myc seems to be the most effective gene and a strict requirement for the presence of mitogens in the growth medium is identified, in effect constituting a conditional perpetuality or immortalization of the human neural stem cell line HNSC.100.
TL;DR: In this article, the stem cells derived from the olfactory bulbs of adult patients undergoing particularly invasive neurosurgery were used for transplantation in various neurodegenerative disorders.
Abstract: We have recently isolated stem cells deriving from the olfactory bulbs of adult patients undergoing particularly invasive neurosurgery. After improving our experimental conditions, we have now obtained neural stem cells according to clonal analysis. The cells can be expanded, established in continuous cell lines and differentiated into the three classical neuronal phenotypes (neurons, astrocytes, and oligodendrocytes). Also, after exposition to leukemia inhibitory factor, we are able to improve the number of neurons, an ideal biological source for transplantation in various neurodegenerative disorders.
Journal Article•
TL;DR: By the manipulation of mechanical injury, the incorporation and subsequent differentiation of the grafted stem cells into neuronal and glial lineage, including the formation of synapse-like structures, can be achieved, even in the adult rat retina.
Abstract: Purpose In a previous study it has been shown that adult rat hippocampus-derived neural stem cells can be successfully transplanted into neonatal retinas, where they differentiate into neurons and glia, but they cannot be transplanted into adult retinas. In the current study, the effect of mechanical injury to the adult retina on the survival and differentiation of the grafted hippocampal stem cells was determined. Methods Mechanical injury was induced in the adult rat retina by a hooked needle. A cell suspension (containing 90,000 neural stem cells) was slowly injected into the vitreous space. The specimens were processed for immunohistochemical studies at 1, 2, and 4 weeks after the transplantation. Results In the best case, incorporation of grafted stem cells was seen in 50% of the injured retinas. Most of these cells located from the ganglion cell layer through the inner nuclear layer close to the injury site. Immunohistochemically, at 1 week, more than half of the grafted cells expressed nestin. At 4 weeks, some grafted cells showed immunoreactivity for microtubule-associated protein (MAP) 2ab, MAP5, and glial fibrillary acidic protein (GFAP), suggesting progress in differentiation into cells of neuronal and astroglial lineages. However, they showed no immunoreactivity for HPC-1, calbindin, and rhodopsin, which suggests that they did not differentiate into mature retinal neurons. Immunoelectron microscopy revealed the formation of synapse-like structures between graft and host cells. Conclusions By the manipulation of mechanical injury, the incorporation and subsequent differentiation of the grafted stem cells into neuronal and glial lineage, including the formation of synapse-like structures, can be achieved, even in the adult rat retina.
TL;DR: Gliogenesis, glial stem cells, putative relationships of these cells to each other, factors implicated in gliogenesis, and therapeutic applications of glial precursors are discussed.
Abstract: Multipotential neuroepithelial stem cells are thought to give rise to all the differentiated cells of the central nervous system (CNS). The developmental potential of these multipotent stem cells becomes more restricted as they differentiate into progressively more committed cells and ultimately into mature neurons and glia. In studying gliogenesis, the optic nerve and spinal cord have become invaluable models and the progressive stages of differentiation are being clarified. Multiple classes of glial precursors termed glial restricted precursors (GRP), oligospheres, oligodendrocyte-type2 astrocyte (O-2A) and astrocyte precursor cells (APC) have been identified. Similar classes of precursor cells can be isolated from human neural stem cell cultures and from embryonic stem (ES) cell cultures providing a non-fetal source of such cells. In this review, we discuss gliogenesis, glial stem cells, putative relationships of these cells to each other, factors implicated in gliogenesis, and therapeutic applications of glial precursors.
TL;DR: It is proposed that a balance between antagonistic extrinsic signals regulates temporal changes in an intrinsic property of neural progenitor cells, and FGF2 is a good candidate for such a signal, as it antagonizes the inhibitory effects of younger cortical cells and exogenous BMP4.
Abstract: Temporal changes in progenitor cell responses to extrinsic signals play an important role in development, but little is known about the mechanisms that determine how these changes occur. In the rodent CNS, expression of epidermal growth factor receptors (EGFRs) increases during embryonic development, conferring mitotic responsiveness to EGF among multipotent stem cells. Here we show that cell-cell signaling controls this change. Whereas EGF-responsive stem cells develop on schedule in explant and aggregate cultures of embryonic cortex, co-culture with younger cortical cells delays their development. Exogenous BMP4 mimics the effect of younger cells, reversibly inhibiting changes in EGFR expression and responsiveness. Moreover, blocking endogenous BMP receptors in progenitors with a virus transducing dnBMPR1B accelerates changes in EGFR signaling. This involves a non-cell-autonomous mechanism, suggesting that BMP negatively regulates signal(s) that promote the development of EGF-responsive stem cells. FGF2 is a good candidate for such a signal, as we find that it antagonizes the inhibitory effects of younger cortical cells and exogenous BMP4. These findings suggest that a balance between antagonistic extrinsic signals regulates temporal changes in an intrinsic property of neural progenitor cells.
TL;DR: Spinal cord cells isolated from embryonic day 14 Sprague-Dawley and Fischer 344 rats possess characteristics of precursor cells and are a promising type of transplant for repair of the injured spinal cord.
TL;DR: With increasing embryonic age, the depletions observed in the number of neurospheres generated in vitro in response to FGF2 after exposure to 3H-thy in vivo decreased, suggesting there is an increase in the length of the cell cycle of FGF-responsive neural stem cells through embryonic development.
Abstract: The embryonic forebrain germinal zone contains two separate and additive populations of epidermal growth factor (EGF)- and fibroblast growth factor (FGF)-responsive stem cells that both exhibit self-renewal and multipotentiality. Although cumulative S phase labeling studies have investigated the proliferation kinetics of the overall population of precursor cells within the forebrain germinal zone through brain development, little is known about when and how (symmetrically or asymmetrically) the small subpopulations of stem cells are proliferating in vivo . This has been determined by injecting timed-pregnant mice with high doses of tritiated thymidine ( 3 H-thy) to kill any stem cells proliferating within the striatal germinal zone in vivo and then by assaying for neurosphere formation in vitro . Injections of 0.8 mCi of 3 H-thy given every 2 hr for 12 hr to timed-pregnant mice at E11, E14, and E17 resulted in significant depletions in the number of neurospheres generated by FGF-responsive stem cells at E11 and by EGF-responsive and FGF-responsive stem cells at E14 and E17. With increasing embryonic age, the depletions observed in the number of neurospheres generated in vitro in response to FGF2 after exposure to 3 H-thy in vivo decreased, suggesting there is an increase in the length of the cell cycle of FGF-responsive neural stem cells through embryonic development. The results suggest that the FGF-responsive stem cell population expands between E11 and E14 by dividing symmetrically, but switches to primarily asymmetric division between E14 and E17. The EGF-responsive stem cells arise after E11, and their population expands through symmetric divisions and through asymmetric divisions of FGF-responsive stem cells.
TL;DR: A role for N-CAM and N- CAM ligands in the inhibition of proliferation and the induction of neural differentiation of hippocampal neural progenitor cells is supported.
Abstract: Cell adhesion molecules (CAMs) play important roles during the development of the nervous system On the basis of our previous observations that binding of the neural CAM (N-CAM) inhibits astrocyte proliferation and alters gene expression, we hypothesized that N-CAM may influence the balance between the proliferation and the differentiation of neural progenitor cells Rat and mouse hippocampal progenitor cells were cultured and showed dependence on basic FGF for proliferation, immunoreactivity for nestin, the presence of limited numbers of differentiated cells, and the ability to generate glial cells and neurons under different culture conditions Addition of soluble N-CAM reduced cell proliferation in a dose-dependent manner with no evidence of apoptosis The inhibition of proliferation by N-CAM was accompanied by an induction of differentiation to the neuronal lineage, as indicated by a twofold increase in the percentage of microtubule-associated protein 2-positive cells even in the presence of mitogenic growth factors Experiments using hippocampal cells from N-CAM knock-out mice indicated that N-CAM on the cell surface is not required for these effects, suggesting the existence of heterophilic signaling These results support a role for N-CAM and N-CAM ligands in the inhibition of proliferation and the induction of neural differentiation of hippocampal neural progenitor cells
TL;DR: This work presents a detailed fate map of the chick caudal neural plate (CNP), a cell population that generates the posterior hindbrain and spinal cord and suggests that neural and epidermal cell fates are acquired on a cell-by-cell basis within the CNP in a manner strikingly similar to that in the fly.
TL;DR: This review addresses the contribution that bone marrow-derived stem cells may play during neurogenesis in mice by transplanted male bone marrow into female recipients to track and characterize the Y chromosome containing cells in the CNS of mice.
TL;DR: This article showed that neurosphere cultures contain a relatively high number of cells that stain weakly with Hoechst 33342, which is present when cultured as an entire batch in the presence of epidermal growth factor (EGF).
Abstract: Background
Neural stem cell research regularly utilizes neurosphere cultures as a continuous source of primitive neural cells. Results from current progenitor cell assays show that these cultures contain a low number of neural progenitors. Our goal is to characterize neurosphere cultures and define subpopulations in order to purify neural progenitor cells.
Methods
Cells from embryonic mouse neurosphere cultures were stained with Hoechst 33342 and analyzed by flow cytometry. Subpopulations were sorted based on their relative fluorescence intensity in the blue and red regions of the spectrum. Individual sorted subpopulations were reanalyzed after 7 days in culture.
Results
Neurosphere cultures contain a relatively high number of cells that stain weakly with Hoechst 33342. This subpopulation is present when cultured as an entire batch in the presence of epidermal growth factor (EGF). When cultured separately, this subpopulation gives rise to a neurosphere population with essentially the same characteristics as freshly isolated embryonic mouse brain cells but contains substantially fewer weakly Hoechst-stained cells.
Conclusions
Similar to hemopoietic systems, neurosphere cultures contain a subpopulation that can be characterized by a low emission of Hoechst fluorescence. When cultured separately, this subpopulation gives rise to a phenotype similar to freshly isolated, uncultured neural cells. Cytometry 40:245–250, 2000 © 2000 Wiley-Liss, Inc.
TL;DR: Data suggest that the DA-depleted striatum offers a suitable environment for MS stem (progenitor) cells to differentiate into mature DAergic neurons, andRosette-like cell aggregation and dysfunction of the blood-brain barrier (BBB) were less in and around the grafts in DA- Depleted Striatum, suggesting less proliferation and more differentiation of MS stem cells in DA.
TL;DR: Findings highlight important differences between humans and rodents in regard to the way epigenetic cues regulate the function of neural stem cells.
Abstract: The generation of diverse types of neural cells during development occurs through the progressive restriction of the fate potential of neuroepithelial progenitor cells. This process is controlled by factors intrinsic and extrinsic to the cell. While the effect of extrinsic cues on multipotent stem cells of the murine central nervous system (CNS) is becoming clearer, little is known of neural stem cells of human origin. We sought to establish the roles played by two cytokines, leukemia inhibitory (LIF) and ciliary neurotrophic factor (CNTF), and by nerve growth factor (NGF) and platelet-derived growth factor (PDGF) in regulating neuronal and astroglial differentiation in cultured embryonic diencephalic human stem cells. While NGF did not influence either neuronal or glial formation, PDGF surprisingly decreased the percentage of stem cell-generated neurons, an effect opposite to that observed in murine progenitors. Furthermore, while we confirmed the known ability of LIF and CNTF to support astroglial differentiation, we also observed that, in contrast with their murine counterparts, the fraction of CNS stem cell-generated neurons in human cultures was enhanced twofold in the presence of both cytokines. These findings highlight important differences between humans and rodents in regard to the way epigenetic cues regulate the function of neural stem cells.