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In the search for ways to combat degenerative neurological disorders,neurogenesis-stimulating factors are proving to be a promising area of research. In this study,we show that the hormonal factor prolactin (PRL) can activate a pool of latent precursor cells in the adult mouse hippocampus. Using an in vitro neurosphere assay,we found that the addition of exogenous PRL to primary adult hippocampal cells resulted in an approximate 50% increase in neurosphere number. In addition,direct infusion of PRL into the adult dentate gyrus also resulted in a significant increase in neurosphere number. Together these data indicate that exogenous PRL can increase hippocampal precursor numbers both in vitro and in vivo. Conversely,PRL null mice showed a significant reduction (approximately 80%) in the number of hippocampal-derived neurospheres. Interestingly,no deficit in precursor proliferation was observed in vivo,indicating that in this situation other niche factors can compensate for a loss in PRL. The PRL loss resulted in learning and memory deficits in the PRL null mice,as indicated by significant deficits in the standard behavioral tests requiring input from the hippocampus. This behavioral deficit was rescued by direct infusion of recombinant PRL into the hippocampus,indicating that a lack of PRL in the adult mouse hippocampus can be correlated with impaired learning and memory. View Publication

Prion diseases are irreversible progressive neurodegenerative diseases,leading to severe incapacity and death. They are characterized in the brain by prion amyloid deposits,vacuolisation,astrocytosis,neuronal degeneration,and by cognitive,behavioural and physical impairments. There is no treatment for these disorders and stem cell therapy therefore represents an interesting new approach. Gains could not only result from the cell transplantation,but also from the stimulation of endogenous neural stem cells (NSC) or by the combination of both approaches. However,the development of such strategies requires a detailed knowledge of the pathology,particularly concerning the status of the adult neurogenesis and endogenous NSC during the development of the disease. During the past decade,several studies have consistently shown that NSC reside in the adult mammalian central nervous system (CNS) and that adult neurogenesis occurs throughout the adulthood in the subventricular zone of the lateral ventricle or the Dentate Gyrus of the hippocampus. Adult NSC are believed to constitute a reservoir for neuronal replacement during normal cell turnover or after brain injury. However,the activation of this system does not fully compensate the neuronal loss that occurs during neurodegenerative diseases and could even contribute to the disease progression. We investigated here the status of these cells during the development of prion disorders. We were able to show that NSC accumulate and replicate prions. Importantly,this resulted in the alteration of their neuronal fate which then represents a new pathologic event that might underlie the rapid progression of the disease. View Publication

X-linked dystonia-parkinsonism (XDP) is a hereditary neurodegenerative disorder involving a progressive loss of striatal medium spiny neurons. The mechanisms underlying neurodegeneration are not known,in part because there have been few cellular models available for studying the disease. The XDP haplotype consists of multiple sequence variations in a region of the X chromosome containingTAF1,a large gene with at least 38 exons,and a multiple transcript system (MTS) composed of five unconventional exons. A previous study identified an XDP-specific insertion of a SINE-VNTR-Alu (SVA)-type retrotransposon in intron 32 ofTAF1,as well as a neural-specific TAF1 isoform,N-TAF1,which showed decreased expression in post-mortem XDP brain compared with control tissue. Here,we generated XDP patient and control fibroblasts and induced pluripotent stem cells (iPSCs) in order to further probe cellular defects associated with this disease. As initial validation of the model,we compared expression ofTAF1and MTS transcripts in XDP versus control fibroblasts and iPSC-derived neural stem cells (NSCs). Compared with control cells,XDP fibroblasts exhibited decreased expression ofTAF1transcript fragments derived from exons 32-36,a region spanning the SVA insertion site. N-TAF1,which incorporates an alternative exon (exon 34'),was not expressed in fibroblasts,but was detectable in iPSC-differentiated NSCs at levels that were ∼threefold lower in XDP cells than in controls. These results support the previous findings that N-TAF1 expression is impaired in XDP,but additionally indicate that this aberrant transcription might occur in neural cells at relatively early stages of development that precede neurodegeneration. View Publication

Mitochondria are a major target for aging and are instrumental in the age-dependent deterioration of the human brain,but studying mitochondria in aging human neurons has been challenging. Direct fibroblast-to-induced neuron (iN) conversion yields functional neurons that retain important signs of aging,in contrast to iPSC differentiation. Here,we analyzed mitochondrial features in iNs from individuals of different ages. iNs from old donors display decreased oxidative phosphorylation (OXPHOS)-related gene expression,impaired axonal mitochondrial morphologies,lower mitochondrial membrane potentials,reduced energy production,and increased oxidized proteins levels. In contrast,the fibroblasts from which iNs were generated show only mild age-dependent changes,consistent with a metabolic shift from glycolysis-dependent fibroblasts to OXPHOS-dependent iNs. Indeed,OXPHOS-induced old fibroblasts show increased mitochondrial aging features similar to iNs. Our data indicate that iNs are a valuable tool for studying mitochondrial aging and support a bioenergetic explanation for the high susceptibility of the brain to aging. View Publication

Adipose tissue stem cells (ADSCs) would be an attractive autologous cell source. However,ADSCs require invasive procedures,and has potential complications. Recently,urine stem cells (USCs) have been proposed as an alternative stem cell source. In this study,we compared USCs and ADSCs collected from the same patients on stem cell characteristics and capacity to differentiate into various cell lineages to provide a useful guideline for selecting the appropriate type of cell source for use in clinical application. The urine samples were collected via urethral catheterization,and adipose tissue was obtained from subcutaneous fat tissue during elective laparoscopic kidney surgery from the same patient (n = 10). Both cells were plated for primary culture. Cell proliferation,colony formation,cell surface markers,immune modulation,chromosome stability and multi-lineage differentiation were analyzed for each USCs and ADSCs at cell passage 3,5,and 7. USCs showed high cell proliferation rate,enhanced colony forming ability,strong positive for stem cell markers expression,high efficiency for inhibition of immune cell activation compared to ADSCs at cell passage 3,5,and 7. In chromosome stability analysis,both cells showed normal karyotype through all passages. In analysis of multi-lineage capability,USCs showed higher myogenic,neurogenic,and endogenic differentiation rate,and lower osteogenic,adipogenic,and chondrogenic differentiation rate compared to ADSCs. Therefore,we expect that USC can be an alternative autologous stem cell source for muscle,neuron and endothelial tissue reconstruction instead of ADSCs. View Publication

Schizophrenia has been considered a devastating clinical syndrome rather than a single disease. Nevertheless,the mechanisms behind the onset of schizophrenia have been only partially elucidated. Several studies propose that levels of trace elements are abnormal in schizophrenia; however,conflicting data generated from different biological sources prevent conclusions being drawn. In this work,we used synchrotron radiation X-ray microfluorescence spectroscopy to compare trace element levels in neural progenitor cells (NPCs) derived from two clones of induced pluripotent stem cell lines of a clozapine-resistant schizophrenic patient and two controls. Our data reveal the presence of elevated levels of potassium and zinc in schizophrenic NPCs. Neural cells treated with valproate,an adjunctive medication for schizophrenia,brought potassium and zinc content back to control levels. These results expand the understanding of atomic element imbalance related to schizophrenia and may provide novel insights for the screening of drugs to treat mental disorders. ?? 2014 Elsevier B.V. View Publication

Several transcription factors (TFs) have been implicated in neuroectoderm (NE) development,and recently,the TF PAX6 was shown to be critical for human NE specification. However,microRNA networks regulating human NE development have been poorly documented. We hypothesized that microRNAs activated by PAX6 should promote NE development. Using a genomics approach,we identified PAX6 binding sites and active enhancers genome-wide in an in vitro model of human NE development that was based on neural differentiation of human embryonic stem cells (hESC). PAX6 binding to active enhancers was found in the proximity of several microRNAs,including hsa-miR-135b. MiR-135b was activated during NE development,and ectopic expression of miR-135b in hESC promoted differentiation toward NE. MiR-135b promotes neural conversion by targeting components of the TGF-β and BMP signaling pathways,thereby inhibiting differentiation into alternate developmental lineages. Our results demonstrate a novel TF-miRNA module that is activated during human neuroectoderm development and promotes the irreversible fate specification of human pluripotent cells toward the neural lineage. View Publication