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Skin-derived precursor (SKP) cells are a valuable resource for tissue engineering and regenerative medicine,because they represent multipotent stem cells that differentiate into neural and mesodermal progenies. Previous studies suggest that the stem cell pool decreases with age. Here,we show that human multipotent SKP cells can be efficiently collected from adult cheek/chin skin,even in aged individuals of 70-78years. SKP cells were isolated from 38 skin samples by serum-free sphere culture and examined for the ability to differentiate into neural and mesodermal lineages. The number of spheres obtained from adult facial skin was significantly higher than that of trunk or extremity skin. SKP cells derived from cheek/chin skin exhibited a high ability to differentiate into neural and mesodermal cells relative to those derived from eyelid,trunk,or extremity skin. Furthermore,cheek/chin skin SKP cells were shown to express markers for undifferentiated stem cells,including a high expression level of the Sox9 gene. These results indicate that cheek/chin skin is useful for the recovery of multipotent stem cells for tissue engineering and regenerative therapy. View Publication

Glioblastoma multiforme (GBM) is a grade IV malignant brain tumor with high mortality and has been well known to involve many molecular pathways,including G-protein coupled receptor (GPCR)-mediated signaling (such as epithelial growth factor receptor [EGFR] and platelet derived growth factor receptor [PDGFR]). G protein-coupled receptor kinases (GRK) directly regulate GPCR activity by phosphorylating activated agonist-bound receptors to desensitize signaling and internalize receptors through beta-arrestins. Recent studies in various cancers,including prostate and breast cancer,have highlighted the role of change in GRK expression to oncogenesis and tumor proliferation. In this study,we evaluated the expression of GRK5 in grade II to grade IV glioma specimens using immunohistochemistry and found that GRK5 expression levels are highly correlated with aggressiveness of glioma. We used culture conditions to selectively promote the growth of either glioblastoma cells with stem cell markers (GSC) or differentiated glioblastoma cells (DGC) from fresh GBM specimens. GSC are known to be highly invasive and mobile,and have the capacity to self-renew and are more resistant to chemotherapy and radiation compared to differentiated populations of GBM. We examined the expression of GRK5 in these two sets of culturing conditions for GBM cells and found that GRK5 expression is upregulated in GSC compared to differentiated GBM cells. To better understand the role of GRK5 in GBM-derived stem cells,we created stable GRK5 knockdown and evaluated the proliferation rate. Using an ATP chemiluminescence assay,we show,for the first time,that knocking down the expression of GRK5 decreased the proliferation rate of GSC in contrast to control. View Publication

BACKGROUND Neural stem cells (NSCs) display tissue trophic and immune modulatory therapeutic activities after transplantation in central nervous system disorders. The intercellular interplay between stem cells and target immune cells is increased in NSCs exposed to inflammatory cues. Here,we hypothesize that inflammatory cytokine signalling leads to metabolic reprogramming of NSCs regulating some of their immune modulatory effects. METHODS NSC lines were prepared from the subventricular zone (SVZ) of 7-12-week-old mice. Whole secretome-based screening and analysis of intracellular small metabolites was performed in NSCs exposed to cocktails of either Th1-like (IFN-γ,500 U/ml; TNF-α,200 U/ml; IL-1β,100 U/ml) or Th2-like (IL-4,IL-5 and IL-13; 10 ng/ml) inflammatory cytokines for 16 h in vitro. Isotopologues distribution of arginine and downstream metabolites was assessed by liquid chromatography/mass spectrometry in NSCs incubated with U-(13)C6 L-arginine in the presence or absence of Th1 or Th2 cocktails (Th1 NSCs or Th2 NSCs). The expression of arginase I and II was investigated in vitro in Th1 NSCs and Th2 NSCs and in vivo in the SVZ of mice with experimental autoimmune encephalomyelitis,as prototypical model of Th1 cell-driven brain inflammatory disease. The effects of the inflammatory cytokine signalling were studied in NSC-lymph node cells (LNC) co-cultures by flow cytometry-based analysis of cell proliferation following pan-arginase inhibition with N(ω)-hydroxy-nor-arginine (nor-NOHA). RESULTS Cytokine-primed NSCs showed significantly higher anti-proliferative effect in co-cultures vs. control NSCs. Metabolomic analysis of intracellular metabolites revealed alteration of arginine metabolism and increased extracellular arginase I activity in cytokine-primed NSCs. Arginase inhibition by nor-NOHA partly rescued the anti-proliferative effects of cytokine-primed NSCs. CONCLUSIONS Our work underlines the use of metabolic profiling as hypothesis-generating tools that helps unravelling how stem cell-mediated mechanisms of tissue restoration become affected by local inflammatory responses. Among different therapeutic candidates,we identify arginase signalling as novel metabolic determinant of the NSC-to-immune system communication. View Publication

A commonly activated signaling cascade in many human malignancies,including glioblastoma multiforme,is the Akt pathway. This pathway can be activated via numerous upstream alterations including genomic amplification of epidermal growth factor receptor,PTEN deletion,or PIK3CA mutations. In this study,we screened phosphatidylinositol 3-kinase/Akt small-molecule inhibitors in an isogenic cell culture system with an activated Akt pathway secondary to a PIK3CA mutation. One small molecule,A-443654,showed the greatest selective inhibition of cells with the mutant phenotype. Based on these findings,this inhibitor was screened in vitro against a panel of glioblastoma multiforme cell lines. All cell lines tested were sensitive to A-443654 with a mean IC(50) of approximately 150 nmol/L. An analogue of A-443654,methylated at a region that blocks Akt binding,was on average 36-fold less active. Caspase assays and dual flow cytometric analysis showed an apoptotic mechanism of cell death. A-443654 was further tested in a rat intracranial model of glioblastoma multiforme. Animals treated intracranially with polymers containing A-443654 had significantly extended survival compared with control animals; animals survived 79% and 43% longer than controls when A-443654-containing polymers were implanted simultaneously or in a delayed fashion,respectively. This small molecule also inhibited glioblastoma multiforme stem-like cells with similar efficacy compared with traditionally cultured glioblastoma multiforme cell lines. These results suggest that local delivery of an Akt small-molecule inhibitor is effective against experimental intracranial glioma,with no observed resistance to glioblastoma multiforme cells grown in stem cell conditions. View Publication

The enteric nervous system (ENS) is composed of neural crest-derived neurons (also known as ganglion cells) the cell bodies of which are located in the submucosal and myenteric plexuses of the intestinal wall. Intramucosal ganglion cells are known to exist but are rare and often considered ectopic. Also derived from the neural crest are enteric glial cells that populate the ganglia and the associated nerves,as well as the lamina propria of the intestinal mucosa. In Hirschsprung disease (HSCR),ganglion cells are absent from the distal gut because of a failure of neural crest-derived progenitor cells to complete their rostrocaudal migration during embryogenesis. The fate of intramucosal glial cells in human HSCR is essentially unknown. We demonstrate a network of intramucosal cells that exhibit dendritic morphology typical of neurons and glial cells. These dendritic cells are present throughout the human gut and express Tuj1,S100,glial fibrillary acidic protein,CD56,synaptophysin,and calretinin,consistent with mixed or overlapping neuroglial differentiation. The cells are present in aganglionic colon from patients with HSCR,but with an altered immunophenotype. Coexpression of Tuj1 and HNK1 in this cell population supports a neural crest origin. These findings extend and challenge the current understanding of ENS microanatomy and suggest the existence of an intramucosal population of neural crest-derived cells,present in HSCR,with overlapping immunophenotype of neurons and glia. Intramucosal neuroglial cells have not been previously recognized,and their presence in HSCR poses new questions about ENS development and the pathobiology of HSCR that merit further investigation. View Publication

INTRODUCTION Hirschsprung's disease is characterized by a developmental arrest of neural crest cell migration,causing distal aganglionosis. Transplanted cells derived from the neural crest may regenerate enteric ganglia in this condition. We investigated the potential of skin-derived precursor cells (SKPs) to engraft and to differentiate into enteric ganglia in aganglionic rat intestine in vivo. METHODS Adult Lewis rat jejunal segments were separated from intestinal continuity and treated with benzalkonium chloride to induce aganglionosis. Ganglia were identified via immunohistochemical stains for S100 and β-III tubulin (TUJ1). SKPs were procured from neonatal Lewis rats expressing enhanced green fluorescent protein (GFP) and cultured in neuroglial-selective media. SKP cell line expansion was quantified,and immunophenotypes were assessed by immunocytochemistry. Aganglionic segments underwent SKP transplantation 21-79days after benzalkonium chloride treatment. The presence of GFP+cells,mature neurons,and mature glia was evaluated at posttransplant days 1,6,and 9. RESULTS Benzalkonium chloride-induced aganglionosis persisted for at least 85days. Prior to differentiation,SKPs expressed S100,denoting neural crest lineage,and nestin,a marker of neuronal precursors. Differentiated SKPs in vitro expressed GFAP,a marker of glial differentiation,as well as TUJ1 and several enteric neurotransmitters. After transplantation,GFP+structures resembling ganglia were identified between longitudinal and circular smooth muscle layers. CONCLUSION SKPs are capable of engraftment,migration,and differentiation within aganglionic rodent intestine in vivo. Differentiated SKPs generate structures that resemble enteric ganglia. Our observations suggest that SKPs represent a potential gangliogenic therapeutic agent for Hirschsprung's disease. View Publication

Glioblastoma (GBM) is the most aggressive primary brain tumor and is resistant to all therapeutic regimens. Relapse occurs regularly and might be caused by a poorly characterized tumor stem cell (TSC) subpopulation escaping therapy. We suggest aldehyde dehydrogenase 1 (ALDH1) as a novel stem cell marker in human GBM. Using the neurosphere formation assay as a functional method to identify brain TSCs,we show that high protein levels of ALDH1 facilitate neurosphere formation in established GBM cell lines. Even single ALDH1 positive cells give rise to colonies and neurospheres. Consequently,the inhibition of ALDH1 in vitro decreases both the number of neurospheres and their size. Cell lines without expression of ALDH1 do not form tumor spheroids under the same culturing conditions. High levels of ALDH1 seem to keep tumor cells in an undifferentiated,stem cell-like state indicated by the low expression of beta-III-tubulin. In contrast,ALDH1 inhibition induces premature cellular differentiation and reduces clonogenic capacity. Primary cell cultures obtained from fresh tumor samples approve the established GBM cell line results. View Publication

The derivation of astrocytes from human pluripotent stem cells is currently slow and inefficient. We demonstrate that overexpression of the transcription factors SOX9 and NFIB in human pluripotent stem cells rapidly and efficiently yields homogeneous populations of induced astrocytes. In our study these cells exhibited molecular and functional properties resembling those of adult human astrocytes and were deemed suitable for disease modeling. Our method provides new possibilities for the study of human astrocytes in health and disease. View Publication

Retinal ganglion cells (RGCs) are the projection neurons of the retina and transmit visual information to postsynaptic targets in the brain. While this function is shared among nearly all RGCs,this class of cell is remarkably diverse,comprised of multiple subtypes. Previous efforts have identified numerous RGC subtypes in animal models,but less attention has been paid to human RGCs. Thus,efforts of this study examined the diversity of RGCs differentiated from human pluripotent stem cells (hPSCs) and characterized defined subtypes through the expression of subtype-specific markers. Further investigation of these subtypes was achieved using single-cell transcriptomics,confirming the combinatorial expression of molecular markers associated with these subtypes,and also provided insight into more subtype-specific markers. Thus,the results of this study describe the derivation of RGC subtypes from hPSCs and will support the future exploration of phenotypic and functional diversity within human RGCs. View Publication