title: Culture under low physiological oxygen conditions improves the stemness and quality of induced pluripotent stem cells.
abstract: The ex vivo expansion of stem cells under low physiological oxygen (O2 ) conditions has been demonstrated to improve the stemness and genomic stability of the cells. We investigated whether low-oxygen culture would be beneficial for the culture of induced pluripotent stem (iPS) cells. Two human iPS cell lines (201B7 and 253G1) were used for the experiments. Cells expanded from a single colony of each cell line were initiated for culture in 2.5% O2 , 5% O2 , or 20% O2 and maintained for 2 months in parallel. The levels of intracellular and mitochondrial reactive oxygen species did not differ between the cells cultured under different conditions. More colonies of uniformly smaller size were observed at 2.5% and 5% O2 than at 20% O2 . All of these iPS colonies that expanded under the various oxygen conditions stained positively for Oct3/4, Nanog, SSEA-4, and ALP. However, Western blot analysis showed that the iPS cells cultured at 2.5% and 5% O2 expressed significantly more Nanog but less 53BP1 than those cultured at 20% O2 . Data from an array CGH showed no significant chromosomal abnormalities, although some genes involved in cellular and metabolic processes were amplified in the low oxygen culture, particularly at 2.5% O2 . Our data suggest that low physiological oxygen culture could improve the stemness and quality of iPS cells, a result that might be associated with the amplification of genes involved in metabolic and cellular processes. Long-term culture will be necessary to confirm whether low physiological oxygen levels also improve genomic stability.
authors.affiliation: Department of Stem Cell Biology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Chao-Wan
authors.initials: CW
authors.lastname: Guo
authors.forename: Miho
authors.initials: M
authors.lastname: Kawakatsu
authors.forename: Marie
authors.initials: M
authors.lastname: Idemitsu
authors.forename: Yoshishige
authors.initials: Y
authors.lastname: Urata
authors.forename: Shinji
authors.initials: S
authors.lastname: Goto
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Ono
authors.forename: Kimikazu
authors.initials: K
authors.lastname: Hamano
authors.forename: Tao-Sheng
authors.initials: TS
authors.lastname: Li
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D002452:Cell Count; D018929:Cell Culture Techniques / Q000379:methods*; D018797:Cell Cycle Proteins / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D048429:Cell Size; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D055028:Comparative Genomic Hybridization; D004249:DNA Damage; D004260:DNA Repair / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000378:metabolism; D015894:Genome, Human / Q000235:genetics; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D010100:Oxygen / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D000071857:Tumor Suppressor p53-Binding Protein 1
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D017382:Reactive Oxygen Species; C498301:TP53BP1 protein, human; D025521:Tumor Suppressor Proteins; D000071857:Tumor Suppressor p53-Binding Protein 1; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; D010100:Oxygen