title: Enhanced proliferation, survival, and dopaminergic differentiation of CNS precursors in lowered oxygen.
abstract: Standard cell culture systems impose environmental oxygen (O(2)) levels of 20%, whereas actual tissue O(2) levels in both developing and adult brain are an order of magnitude lower. To address whether proliferation and differentiation of CNS precursors in vitro are influenced by the O(2) environment, we analyzed embryonic day 12 rat mesencephalic precursor cells in traditional cultures with 20% O(2) and in lowered O(2) (3 +/- 2%). Proliferation was promoted and apoptosis was reduced when cells were grown in lowered O(2), yielding greater numbers of precursors. The differentiation of precursor cells into neurons with specific neurotransmitter phenotypes was also significantly altered. The percentage of neurons of dopaminergic phenotype increased to 56% in lowered O(2) compared with 18% in 20% O(2). Together, the increases in total cell number and percentage of dopaminergic neurons resulted in a ninefold net increase in dopamine neuron yield. Differential gene expression analysis revealed more abundant messages for FGF8, engrailed-1, and erythropoietin in lowered O(2). Erythropoietin supplementation of 20% O(2) cultures partially mimicked increased dopaminergic differentiation characteristic of CNS precursors cultured in lowered O(2). These data demonstrate increased proliferation, reduced cell death, and enhanced dopamine neuron generation in lowered O(2), making this method an important advance in the ex vivo generation of specific neurons for brain repair.
authors.affiliation: Laboratory of Molecular Biology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: L
authors.initials: L
authors.lastname: Studer
authors.forename: M
authors.initials: M
authors.lastname: Csete
authors.forename: S H
authors.initials: SH
authors.lastname: Lee
authors.forename: N
authors.initials: N
authors.lastname: Kabbani
authors.forename: J
authors.initials: J
authors.lastname: Walikonis
authors.forename: B
authors.initials: B
authors.lastname: Wold
authors.forename: R
authors.initials: R
authors.lastname: McKay
mesh_terms: D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D001973:Bromodeoxyuridine; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D015687:Cell Hypoxia / Q000502:physiology*; D019070:Cell Lineage / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002490:Central Nervous System / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D004921:Erythropoietin / Q000378:metabolism / Q000494:pharmacology; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism / Q000494:pharmacology; D020287:In Situ Nick-End Labeling; D010100:Oxygen / Q000378:metabolism*; D051381:Rats; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000943:Antigens, Differentiation; D016222:Fibroblast Growth Factor 2; D004921:Erythropoietin; D001973:Bromodeoxyuridine; D010100:Oxygen; D004298:Dopamine