Neurosphere

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

Human embryonic stem cell neural differentiation and enhanced cell survival promoted by hypoxic preconditioning

Abstract: Transplantation of neural progenitors derived from human embryonic stem cells (hESCs) provides a potential therapy for ischemic stroke. However, poor graft survival within the host environment has hampered the benefits and applications of cell-based therapies. The present investigation tested a preconditioning strategy to enhance hESC tolerance, thereby improving graft survival and the therapeutic potential of hESC transplantation. UC06 hESCs underwent neural induction and terminal differentiation for up to 30 days, becoming neural lineage cells, exhibiting extensive neurites and axonal projections, generating synapses and action potentials. To induce a cytoprotective phenotype, hESC-derived neurospheres were cultured at 0.1% oxygen for 12 h, dissociated and plated for terminal differentiation under 21% oxygen. Immunocytochemistry and electrophysiology demonstrated the ‘hypoxic preconditioning’ promoted neuronal differentiation. Western blotting revealed significantly upregulated oxygen-sensitive transcription factors hypoxia-inducible factor (HIF)-1α and HIF-2α, while producing a biphasic response within HIF targets, including erythropoietin, vascular endothelial growth factor and Bcl-2 family members, during hypoxia and subsequent reoxygenation. This cytoprotective phenotype resulted in a 50% increase in both total and neural precursor cell survival after either hydrogen peroxide insult or oxygen–glucose deprivation. Cellular protection was maintained for at least 5 days and corresponded to upregulation of neuroprotective proteins. These results suggest that hypoxic preconditioning could be used to improve the effectiveness of human neural precursor transplantation therapies.

Pleiotropic functions of PACAP in the CNS: neuroprotection and neurodevelopment.

Abstract: Pituitary adenylate cyclase-activating polypeptide (PACAP) is a pleiotropic neuropeptide that belongs to the secretin/glucagon/vasoactive intestinal peptide (VIP) family. PACAP prevents ischemic delayed neuronal cell death (apoptosis) in the hippocampus. PACAP inhibits the activity of the mitogen-activated protein kinase (MAPK) family, especially JNK/SAPK and p38, thereby protecting against apoptotic cell death. After the ischemia-reperfusion, both pyramidal cells and astrocytes increased their expression of the PACAP receptor (PAC1-R). Reactive astrocytes increased their expression of PAC1-R, released interleukin-6 (IL-6) that is a proinflammatory cytokine with both differentiation and growth-promoting effects for a variety of target cell types, and thereby protected neurons from apoptosis. These results suggest that PACAP itself and PACAP-stimulated secretion of IL-6 synergistically inhibit apoptotic cell death in the hippocampus. The PAC1-R is expressed in the neuroepithelial cells from early developmental stages and in various brain regions during development. We have recently found that PACAP, at physiological concentrations, induces differentiation of mouse neural stem cells into astrocytes. Neural stem cells were prepared from the telencephalon of mouse embryos and cultured with basic fibroblast growth factor. The PAC1-R immunoreactivity was demonstrated in the neural stem cells. When neural stem cells were exposed to PACAP, about half of these cells showed glial fibrillary acidic protein (GFAP) immunoreactivity. This phenomenon was significantly antagonized by a PAC1-R antagonist (PACAP6-38), indicating that PACAP induces differentiation of neural stem cell into astrocytes. Other our physiological studies have demonstrated that PACAP acts on PAC1-R in mouse neural stem cells and its signal is transmitted to the PAC1-R-coupled G protein Gq but not to Gs. These findings strongly suggest that PACAP plays very important roles in neuroprotection in adult brain as well as astrocyte differentiation during development.

Cells enriched in markers of neural tissue-committed stem cells reside in the bone marrow and are mobilized into the peripheral blood following stroke.

Abstract: The concept that bone marrow (BM)-derived cells participate in neural regeneration remains highly controversial and the identity of the specific cell type(s) involved remains unknown. We recently reported that the BM contains a highly mobile population of CXCR4+ cells that express mRNA for various markers of early tissue-committed stem cells (TCSCs), including neural TCSCs. Here, we report that these cells not only express neural lineage markers (beta-III-tubulin, Nestin, NeuN, and GFAP), but more importantly form neurospheres in vitro. These neural TCSCs are present in significant amounts in BM harvested from young mice but their abundance and responsiveness to gradients of motomorphogens, such as SDF-1, HGF, and LIF, decreases with age. FACS analysis, combined with analysis of neural markers at the mRNA and protein levels, revealed that these cells reside in the nonhematopoietic CXCR4+/Sca-1+/lin-/CD45 BM mononuclear cell fraction. Neural TCSCs are mobilized into the peripheral-blood following stroke and chemoattracted to the damaged neural tissue in an SDF-1-CXCR4-, HGF-c-Met-, and LIF-LIF-R-dependent manner. Based on these data, we hypothesize that the postnatal BM harbors a nonhematopoietic population of cells that express markers of neural TCSCs that may account for the beneficial effects of BM-derived cells in neural regeneration.

Characterisation and transplantation of enteric nervous system progenitor cells

Abstract: Aims: Enteric nervous system (ENS) progenitor cells have been postulated to be an appropriate source of cells for the treatment of Hirschsprung’s disease. In order for this to be successful, the techniques previously used for the isolation of rodent ENS progenitor cells need to be adapted for postnatal human tissue. In this paper, we describe a method suitable for the preparation of both mouse and human postnatal ENS progenitor cells and assess their transplantation potential. Method: Single cell suspensions were isolated from 11.5 days post-coitum embryonic mouse caecum and postnatal human myenteric plexus. These cells were cultured under non-adherent conditions to generate neurospheres which were implanted into aganglionic embryonic mouse hindgut explants. Cell proliferation, migration and differentiation were observed using immunofluorescence microscopy. Results: Neurospheres generated from both mouse and human tissues contained proliferating neural crest-derived cells that could be expanded in tissue culture to generate both glial cells and neurons. When implanted into aganglionic murine gut, cells migrated from the neurospheres using pathways appropriate for cells derived from the neural crest, and differentiated to become glia and neurons expressing neuronal phenotypic markers characteristic of the ENS including nitric oxide synthase and vasoactive intestinal polypeptide. Conclusion: We have developed a technique for the isolation and expansion of ENS progenitor cells from human neonates. These cells have the ability to differentiate into neurons and glia when transplanted into aganglionic gut, this demonstration being a necessary first step for their autologous transplantation in the treatment of Hirschsprung’s disease.

Plasticity of stem cells derived from adult periodontal ligament.

Abstract: Background: The neural crest contains pluripotent cells that can give rise to neurons and glial cells of the peripheral nervous system, endocrine cells, connective tissue cells, muscle cells and pigment cells during embryonic development. Stem cells derived from the neural crest may still reside in neural crest derivatives including the periodontal ligament (PDL). However, the pluripotency of PDL-derived stem cells has not been investigated. Aim: To identify subpopulations of stem cells from the adult PDL and study their pluripotency. Human PDLs were harvested from impacted wisdom teeth (patients aged 19–22 years). Results: This study demonstrated that subpopulations of PDL cells expressed embryonic stem cell markers (Oct4, Sox2, Nanog and Klf4) and a subset of neural crest markers (Nestin, Slug, p75 and Sox10). Such PDL cell subpopulations exhibited the potential to differentiate into neurogenic, cardiomyogenic, chondrogenic and osteogenic lineages. Furthermore, preliminary evidence suggesting insulin pr...