Hypoxia preconditioned human adipose derived mesenchymal stem cells enhance angiogenic potential via secretion of increased VEGF and bFGF

Abstract

Mesenchymal stem cells (MSCs) are adult multipotent cells found in bone marrow, adipose tissue, and other adult tissues. MSCs improve regeneration of injured tissues in vivo, but the mechanisms remain unclear. Typically, MSCs are cultured under ambient or normoxic conditions (21% O2 ). However, the physiological niches of MSCs have much lower oxygen tension. When used as a therapeutic tool to repair tissue injuries, MSCs cultured in standard conditions must adapt from 21% O2 in culture to <1% O2 in ischemic tissue. We have examined the effects of hypoxia preconditioning (1% O2 ) in human adipose derived mesenchymal stem cells (AD-MSCs) to discover the conditions that best enhance their tissue regenerative potential. We demonstrate that AD-MSCs respond positively to hypoxia compared with normoxia preconditioning, show decreased apoptosis even in severe microenvironmental conditions (such as a low-serum medium), and an increased expression of the angiogenic factors, vascular endothelial growth factor and basic fibroblast growth factor. Human umbilical vein endothelial cells have higher vitality and lower apoptosis when cultured in medium taken from hypoxia-preconditioned AD-MSCs, as well as significantly increased capillary-like structures with this medium on Matrigel. The data suggest that hypoxia preconditioned AD-MSCs can improve tissue regeneration.

Hypoxic and ischemic effects on gene and protein expression levels of paracrine factors by human olfactory mucosa mesenchymal-like stem cells

“…Other investigators have demonstrated an increase in VEGF gene expression and secretion by MSCs in hypoxia. 14,15 Our results generally did demonstrate an increase in VEGF after hypoxia in 20% serum supplement, while the results are the opposite in 5% serum supplement. The serum levels may influence the gene expression for VEGF, so the secretion of VEGF in hypoxia was different between the 20% serum supplement and the 5% serum supplement.…”

“…[9][10][11] There is only 3%-14% oxygen in brain. 12 Hypoxia 13 can affect the secretion of paracrine factors, 14 alter gene expression of MSCs 15,16 and enhance proliferation of MSCs. [17][18][19][20][21] The amount of serum present in the culture media also affects stem cell behavior.…”

“…In addition, hypoxia increased gene expression for trophic/growth factors in MSCs, including BDNF, GDNF and VEGF and its receptor FIK-1; erythropoietin (EPO) and its receptor EPOR; stromal derived factor-1 and its CXC chemokine receptor 4; placental growth factor; heparin-binding epidermal growth factor; MMP-9, and basic fibroblast growth factor (bFGF). 14,15,32 Hypoxia caused an increase in the secretion of transforming growth factor-β2; insulin-like growth factor (IGF) binding proteins 2, 3, 4 and 6; IGF-II and interleukin-7, 33,34 and reduced the secretion of stromal cell derived factor-1, macrophage colony stimulating factor, interleukin-1 receptor antagonist, RANTES, chemokine (C-X-C motif) ligand 1, lactate dehydrogenase and chemokine (C-X-C motif) ligand 10 by MSCs. 16,35 In short, hypoxia changes the paracrine secretions of MSCs, which would have implications for the role they play in reducing the loss of function in the brain after cerebral ischemia.…”

Identifying the Cellular Mechanisms Leading to Heterotopic Ossification

“…Furthermore, when the angiogenic potential of MSCs was investigated in older subjects the resulting data demonstrated a reduced capacity for adipose-derived stem cells (ADSCs) to form capillary-like networks when compared with ADSCs isolated from younger subjects [40]. A MSCs capacity for vascularisation can be improved following hypoxic preconditioning [41]. This is significant given that low oxygen tension can result as a consequence of soft-tissue injury, and may implicate MSCs in ectopic bone formation (see Diagram 1).…”

Hypoxic Preconditioning Increases the Neuroprotective Effects of Mesenchymal Stem Cells in a Rat Model of Spinal Cord Injury

“…In addition, VEGF has neurotrophic and neuroprotective effects in vitro and in vivo [23,24]. Although several studies have demonstrated that VEGF mRNA or protein expression is upregulated in hypoxia-preconditioned MSCs [25][26][27], few reports have demonstrated the neuroprotective effects of hypoxia-preconditioned MSCs transplantation to treat SCI. Therefore, the present study aimed to determine whether hypoxia-preconditioned MSCs have a neuroprotective effect in vitro and in vivo and improve functional defects in a rat model of SCI.…”