title: Mild hypoxia enhances proliferation and multipotency of human neural stem cells.
abstract: BACKGROUND
  Neural stem cells (NSCs) represent an optimal tool for studies and therapy of neurodegenerative diseases. We recently established a v-myc immortalized human NSC (IhNSC) line, which retains stem properties comparable to parental cells. Oxygen concentration is one of the most crucial environmental conditions for cell proliferation and differentiation both in vitro and in vivo. In the central nervous system, physiological concentrations of oxygen range from 0.55 to 8% oxygen. In particular, in the in the subventricular zone niche area, it's estimated to be 2.5 to 3%.
  
  
  RESULTS
  We investigated in vitro the effects of 1, 2.5, 5, and 20% oxygen concentrations on IhNSCs both during proliferation and differentiation. The highest proliferation rate, evaluated through neurosphere formation assay, was obtained at 2.5 and 5% oxygen, while 1% oxygen was most noxious for cell survival. The differentiation assays showed that the percentages of beta-tubIII+ or MAP2+ neuronal cells and of GalC+ oligodendrocytes were significantly higher at 2.5% compared with 1, 5, or 20% oxygen at 17 days in vitro. Mild hypoxia (2.5 to 5% oxygen) promoted differentiation into neuro-oligodendroglial progenitors as revealed by the higher percentage of MAP2+/Ki67+ and GalC+/Ki67+ residual proliferating progenitors, and enhanced the yield of GABAergic and slightly of glutamatergic neurons compared to 1% and 20% oxygen where a significant percentage of GFAP+/nestin+ cells were still present at 17 days of differentiation.
  
  
  CONCLUSIONS
  These findings raise the possibility that reduced oxygen levels occurring in neuronal disorders like cerebral ischemia transiently lead to NSC remaining in a state of quiescence. Conversely, mild hypoxia favors NSC proliferation and neuronal and oligodendroglial differentiation, thus providing an important advance and a useful tool for NSC-mediated therapy of ischemic stroke and neurodegenerative diseases like Parkinson's disease, multiple sclerosis, and Alzheimer's disease.
authors.affiliation: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy.
authors.forename: Guido
authors.initials: G
authors.lastname: Santilli
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Lamorte
authors.forename: Luigi
authors.initials: L
authors.lastname: Carlessi
authors.forename: Daniela
authors.initials: D
authors.lastname: Ferrari
authors.forename: Laura
authors.initials: L
authors.lastname: Rota Nodari
authors.forename: Elena
authors.initials: E
authors.lastname: Binda
authors.forename: Domenico
authors.initials: D
authors.lastname: Delia
authors.forename: Angelo L
authors.initials: AL
authors.lastname: Vescovi
authors.forename: Lidia
authors.initials: L
authors.lastname: De Filippis
mesh_terms: D015153:Blotting, Western; D002453:Cell Cycle; D002454:Cell Differentiation; D049109:Cell Proliferation; D002470:Cell Survival; D006801:Humans; D000860:Hypoxia / Q000473:pathology*; D008564:Membrane Potentials; D008856:Microscopy, Fluorescence; D039902:Multipotent Stem Cells / Q000473:pathology*; D009474:Neurons / Q000473:pathology*; D010100:Oxygen / Q000378:metabolism
chemical_list: D010100:Oxygen