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.

Cannabidiol Reduces Leukemic Cell Size – But Is It Important?

“…Low physiological oxygen culture is thought to be important for stem cell culture, possibly due to the amplification of genes involved in metabolic processes (Guo et al, 2013). This mechanism makes sense with respect to the action of CBD, in that mitochondrial respiration changes under different oxidative environments could impact on the ability of CBD to generate ROS thought to be involved in CBD-induced cell death (McKallip et al, 2006).…”

Hypoxia enhances buffalo adipose‐derived mesenchymal stem cells proliferation, stemness, and reprogramming into induced pluripotent stem cells

“…For enhancing the reprogramming process hypoxic culture conditions are more efficient and faster than in normoxic culture conditions (Bae et al, 2012;Shimada, Hashimoto, Nakada, Shigeno, & Nakamura, 2012;Yoshida, Takahashi, Okita, Ichisaka, & Yamanaka, 2009). Culture under hypoxic conditions improves the stemness and differentiation capacity of iPSCs (Bobis-Wozowicz, Kmiotek-Wasylewska, Madeja, & Zuba-Surma, 2017; Guo et al, 2013), and stabilizes X chromosomes of ESCs in XaXa state (Lengner et al, 2010).…”

Endogenous Factors Causative of Spontaneous DNA Damage that Leads to Random Integration in Human Cells

“…It should be noted that the fact that the low oxygen culture condition is effective in reducing genomic DNA damage as well as unwanted random integration of foreign DNA might have implications for future gene/cell therapy. For example, iPS cells have been shown to be more stably maintained under low oxygen culture conditions ( [37] and our unpublished observations). Even more importantly, as random integration is a major obstacle in gene targeting via homologous recombination, a decreased random integration frequency should be preferable to increasing the frequency of targeted gene inactivation/ correction [7].…”