Locally born olfactory bulb stem cells proliferate in response to insulin-related factors and require endogenous insulin-like growth factor-I for differentiation into neurons and glia

J Neurosci. 2003 Feb 1;23(3):895-906. doi: 10.1523/JNEUROSCI.23-03-00895.2003.

Abstract

After late embryogenesis, new neurons are continuously added to the olfactory bulb (OB) from stem cells located in the forebrain subventricular zone. Nonetheless, stem cells have not been described within the embryonic olfactory bulb. Here we report the isolation of local olfactory bulb stem cells from the embryonic day 12.5-14.5 mouse embryo. These cells were 99.2% nestin positive and proliferated extensively in culture to at least 150 cell doublings. Clonal analysis demonstrated that neurons (TuJ1(+)), astrocytes (GFAP(+)), and oligodendrocytes (O4(+)) could be generated from single-plated cells, indicating that they are multipotent. At least 90% of proliferating cells expressed insulin-like growth factor-I (IGF-I), (pro)insulin, and their cognate receptors; these growth factors collaborated with fibroblast growth factor-2 plus epidermal growth factor (EGF) to promote stem cell proliferation and sphere formation. Cells from Igf-I(-)/- mice, however, proliferated as extensively as did Igf-I(+/+) cells. Differentiation and survival of stem cell-generated neurons and glia showed strong dependence on exogenous IGF-I, but oligodendrocyte differentiation also required insulin at low concentration. Furthermore, the percentages of stem cell-generated neurons, astrocytes, and oligodendrocytes were markedly lower in the cultures prepared from the Igf-I(-)/- mice compared with those of Igf-I(+/+). Concordantly, lack of IGF-I resulted in abnormal formation of the olfactory bulb mitral cell layer and altered radial glia morphology. These results support the presence within the embryonic mouse olfactory bulb of stem cells with specific requirements for insulin-related growth factors for proliferation or differentiation. They demonstrate that IGF-I is an endogenous factor regulating the differentiation of stem and other precursor cells within the olfactory bulb.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain-Derived Neurotrophic Factor / pharmacology
  • Cell Differentiation / drug effects*
  • Cell Differentiation / genetics
  • Cell Differentiation / physiology
  • Cell Division / drug effects
  • Cell Survival / drug effects
  • Cell Survival / physiology
  • Cells, Cultured
  • Clone Cells / cytology
  • Epidermal Growth Factor / pharmacology
  • Fibroblast Growth Factor 2 / pharmacology
  • Growth Substances / pharmacology*
  • Insulin / biosynthesis
  • Insulin / pharmacology
  • Insulin-Like Growth Factor I / biosynthesis
  • Insulin-Like Growth Factor I / genetics
  • Insulin-Like Growth Factor I / pharmacology*
  • Mice
  • Mice, Knockout
  • Nervous System Malformations / genetics
  • Nervous System Malformations / pathology
  • Neuroglia / cytology
  • Neuroglia / drug effects
  • Neurons / cytology
  • Neurons / drug effects
  • Olfactory Bulb / abnormalities
  • Olfactory Bulb / cytology*
  • Olfactory Bulb / embryology
  • Proinsulin / biosynthesis
  • Proinsulin / pharmacology
  • Receptors, Cell Surface / biosynthesis
  • Stem Cells / cytology*
  • Stem Cells / drug effects
  • Stem Cells / metabolism

Substances

  • Brain-Derived Neurotrophic Factor
  • Growth Substances
  • Insulin
  • Receptors, Cell Surface
  • Fibroblast Growth Factor 2
  • Epidermal Growth Factor
  • Insulin-Like Growth Factor I
  • Proinsulin