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

Abstract

A microenvironment low in O₂ (‘physiological' hypoxia) governs the functions of perivascular multipotent mesenchymal stromal cells, defining their involvement in tissue physiological homeostasis and regenerative remodelling. Acute hypoxic stress is considered as one of the important factors inducing tissue damage. Here, we evaluate the influence of short-term hypoxia (1% O₂ for 24 h) on perivascular adipose tissue-derived cells (ASCs) permanently expanded in tissue-related O₂ (5%) microenvironment. After hypoxic exposure, ASCs retained high viability, stromal cell morphology and mesenchymal phenotype (CD73+, CD90+, CD105+ and CD45-). Mild oxidative damage was unveiled as elevation of reactive oxygen species and thiobarbituric acid-active products, while no reduction in the activity of the antioxidant enzymes catalase and glutathione peroxidase and a 20% statistically significant increase in superoxide dismutase activity was detected. Expression of hypoxia-inducible factor (HIF)-1α and HIF-3α isoforms was differently regulated. HIF-1α displayed transient up-regulation, with maximum levels 30 min after acute hypoxic exposure, while HIF-3α was significantly up-regulated after 24 h. Up-regulation of ERK7, MEK1 and c-fos, and down-regulation of MKK6, p53, CCNA2, CCNB1 and CCNB2 were observed after 24 h of oxygen deprivation. Acute hypoxic exposure did not affect the gene expression of other mitogen-activated protein kinases (MAPKs) and MAPK kinases, MAPK/ERK kinase-interacting proteins, MAPK-activated transcription factors and scaffolding proteins. Significant stimulation of vascular endothelial growth factor α and interleukin-6 production was detected in ASC-conditioned medium. Thus, tissue O₂-adapted ASCs are resistant to hypoxic stress, which can ensure their effective involvement in the regeneration of tissue damage under significant oxygen deprivation.

Acute Hypoxic Stress Affects Migration Machinery of Tissue O2‐Adapted Adipose Stromal Cells

“…Firstly, the increased level of intracellular ROS at 0.1% O 2 may enhance the activity of ASC antioxidant systems. Previously, we demonstrated mild oxidative stress followed by an increase in superoxide dismutase activity in ASCs cultured continuously under 5% O 2 [38, 45]. Secondly, the downregulation of TP53 (p53), FASLG (Fas ligand), and APC gene expression and upregulation of SFN (14-3-3 sigma) expression found in this study should prevent apoptotic events.…”

“…Numerous studies of various cell types have shown that HIF-1 α stabilisation has a considerable effect on RhoA activity, which is followed by changes in migration activity [22, 23, 60]. We have previously demonstrated changes in the expression of HIF family transcription factors in tissue O 2 -adapted ASCs after hypoxic stress [45]. Particularly, statistically significant downregulation of HIF-1α and upregulation of HIF-3α expression in ASCs were found 24 h after hypoxic (1% O 2 ) exposure.…”

“…This suggestion is indirectly confirmed by our previous data on the paracrine activity of tissue-adapted O 2 ASCs under acute hypoxia. In addition, we have demonstrated that hypoxic stress stimulates the secretion of proangiogenic factors (VEGF, IL-8) from tissue O 2 -adapted ASCs [45], which should promote angiogenesis. The above results correlate with the findings of other studies, confirming that hypoxic preconditioning promotes MSC angiogenic activity [41, 73].…”

IFN‐gamma priming of adipose‐derived stromal cells at “physiological” hypoxia

“…Further study revealed an attenuation of targeted and non-targeted migration of ASCs after O 2 deprivation (Udartseva et al, 2016). These data appeared to be quite surprising as earlier acute hypoxic exposure of ambient (20%) O 2 -adapted MSCs was shown to enhance migration rate (Buravkova et al, 2014).…”

“…Nevertheless, we were the first to describe ASC “on site” response on acute hypoxic stress. We successfully demonstrated that tissue O 2 ‐adapted ASCs are resistant to short‐term hypoxia, which can ensure their effective involvement in the regeneration of tissue damage under significant oxygen deprivation (Andreeva, Lobanova, Udartseva, & Buravkova, ). Further study revealed an attenuation of targeted and non‐targeted migration of ASCs after O 2 deprivation (Udartseva et al, ).…”