Dissection of the Biphasic Nature of Hypoxia-Induced Motogenic Action in Bone Marrow-Derived Human Mesenchymal Stem Cells

Abstract

Hypoxic conditions have been reported to facilitate preservation of undifferentiated mesenchymal stem cell (MSC) phenotype and positively affect their colony-forming potential, proliferation, and migration/mobilization. In this study, designed to dissect mechanisms underlying hypoxia-dependent migration of bone marrow-derived human MSC (hMSC), signal transduction, and molecular mechanisms were evaluated by integrating morphological, molecular, and cell biology techniques, including the wound healing assay (WHA) and modified Boyden's chamber assay (BCA) to monitor migration. Exposure of hMSCs to moderate hypoxia resulted in a significant increase of migration of hMSCs in both WHA (from 6 to 20 hours) and BCA (within 6 hours). Mechanistic experiments outlined the following sequence of hypoxia-dependent events: (a) very early (15 minutes) increased generation of intracellular reactive oxygen species (ROS), which (b) was sufficient to switch on activation of extracellular regulated kinase 1/2 and c-Jun N-terminal protein kinase 1/2, found to be relevant for the early phase of hMSC migration; (c) hypoxia inducible factor-1 (HIF-1)-dependent increased expression of vascular endothelial growth factor (VEGF) (facilitated by ROS) and its progressive release that was responsible for (d) a delayed and sustained migration of hMSCs. These results suggest that hypoxia-dependent migration relies on a previously unrecognized biphasic scenario involving an early phase, requiring generation of ROS, and a delayed phase sustained by HIF-1-dependent expression and release of VEGF. STEM CELLS 2011;29:952-963 Disclosure of potential conflicts of interest is found at the end of this article.

Dopamine Regulates Mobilization of Mesenchymal Stem Cells during Wound Angiogenesis

“…4A). This result corroborates well with the critical role of VEGF in regulating chemotaxis of MSCs into wound bed as reported by several other studies [15], [31], [34]–[37]. Therefore, further experiments were designed in vitro to evaluate the role of DA on VEGF induced migration of murine MSCs.…”

“…Several recent reports have indicated that VEGF is the predominant growth factor, which regulates wound angiogenesis [30]–[33] and chemotactic migration of MSCs both in vitro and in vivo [14], [15], [31], [34]–[37], therefore further experiments were designed in vitro to determine the direct effect of VEGF on the migration of murine MSCs.…”

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

“…Some authors consider short-term hypoxic exposure of MSCs to be permanently maintained under ambient O 2 (20%) as oxidative stress, which may cause functional impairment due to increased ROS production [Guzy and Schumacker, 2006;Zhang et al, 2009;Busletta et al, 2011;Peterson et al, 2011] in part triggered by a significant increase in prooxidants, such as the ROS producer NAD(P)H oxidase subunits p67phox and p47phox [Peterson et al, 2011]. A decrease in activity of the antioxidant enzyme catalase, a major metaboliser of ROS, without changes in SOD and SOD subunit levels confirmed that the metabolism of ROS was also impaired (or at least not sufficient) [Peterson et al, 2011].…”

Potential benefits of allogeneic bone marrow mesenchymal stem cells for wound healing

“…Under hypoxic conditions, MSC’s are rapidly mobilized 83,84 and are stimulated to secret increased levels of cytokines involved in tissue growth and angiogenesis 32,85 . In fact preconditioning MSC’s in hypoxia has been shown to enhance their tissue regenerative properties 84,86 .…”