Low Oxygen Tension Enhances Proliferation and Maintains Stemness of Adipose Tissue–Derived Stromal Cells

Abstract

Recent evidence indicates that low oxygen tension or hypoxia alters the characteristics of stem cells. The actions of hypoxia are mediated through the hypoxia-inducible factor, a critical mediator of the cellular response to hypoxia. Adipose tissue–derived stromal cells (ASCs) are one of the most promising cell sources for tissue engineering applications. This study investigated the effect of hypoxia on ASCs in terms of the ability to proliferate and differentiate. ASCs were extracted from mice and maintained under hypoxic atmosphere (2% O2) for up to eight in vitro passages. The proliferation rate was examined as a growth curve, and the potency of differentiation was evaluated. To investigate the cell characteristics, we checked several stem-cell markers and growth factors. Compared with the normoxic state (20% O2), hypoxia enhances proliferation with an approximately six- to sevenfold higher ASC expansion over 6 weeks. The expression of Oct3/4 and Nanog (stem-cell marker) and the amount of secreted growth factors were increased under the hypoxic condition. These results suggest that low oxygen tension enhances proliferation and maintains stemness of ASCs. Thus, this study emphasizes the profitability of hypoxic culture for expansion of ASCs and maintenance of their undifferentiated state for further therapeutic use.

Response of Adipose Tissue-Derived Stromal Cells in Tissue-Related O₂ Microenvironment to Short-Term Hypoxic Stress

“…We have shown that the permanent expansion of ASCs at 5% O 2 lowered the cellular ATP level in these cells, diminishing mitochondrial ATP production and stimulating glycolytic ATP production compared to ASCs at standard 20% O 2 [Buravkova et al, 2013]. These data have been confirmed by others [Yamamoto et al, 2013;Choi et al, 2014;Fotia et al, 2014]. The up-regulation of key 'stemness' genes (Oct3/4, Sox2 and Nanog) in ASCs under tissue-related O 2 was demonstrated [Fotia et al, 2014], indicating that in such conditions ASCs possess the phenotype of uncommitted progenitor cells, which is correlated with less pronounced osteo-and adipogenic induction under low O 2 , as mentioned above [Yamamoto et al, 2013;Fotia et al, 2014].…”

Molecular Validation of Chondrogenic Differentiation and Hypoxia Responsiveness of Platelet-Lysate Expanded Adipose Tissue–Derived Human Mesenchymal Stromal Cells

“…The avascularity of the cartilage tissue provides a low oxygen environment for the chondrocytes, whereas oxygen measurements of tissues known to harbor stem cells revealed lower oxygen tension to maintain the stemness of the niche. [38][39][40] In our experiments, we observed an increased expression of HIF1A mRNA levels even in normoxic conditions at early time points in AMSCs. The main regulation of HIF1A occurs at the level of protein stability, and its protein levels are strongly stimulated by low oxygen conditions.…”

Effect of Hypoxia on Stemness and Differentiation of Dental Pulp Derived Stem Cells

“…Densitometry analysis of PCR amplified cDNA of osterix from two groups revealed marginally lower expression of this osteogenic marker gene in induced hypoxic culture [7,31]. Similar observation has been recently reported in case of Adipose Stem Cells, where hypoxia was found to inhibit osteogenic differentiation [32,33]. Similarly, Chondrocytes differentiation was confirmed by Alcian blue staining and RT-PCR for Collagen-II.…”