Submitted on August 5, 2008
Revised on September 25, 2008
Accepted on November 14, 2008
Hyperbaric oxygen stimulates vasculogenic stem cell growth and differentiation in vivo
Tatyana N Milovanova1, Veena M. Bhopale1, Elena M. Sorokina1, Jonni S. Moore1, Thomas K. Hunt2, Martin Hauer-Jensen3, Omaida C. Velazquez4, and Stephen R. Thom1*
1 University of Pennsylvania
2 University of California
3 University of Arkansas for Medical Sciences
4 University of Miami
* To whom correspondence should be addressed. E-mail: sthom{at}mail.med.upenn.edu.
We hypothesized that oxidative stress from hyperbaric oxygen (HBO2, 2.8 ATA for 90 minutes daily) exerts a trophic effect on vasculogenic stem cells. In a mouse model, circulating stem/progenitor cells (SPCs) recruitment and differentiation in subcutaneous Matrigel were stimulated by HBO2 and by a physiological oxidative stressor, lactate. In combination, HBO2 and lactate had additive effects. Vascular channels lined by CD34+ SPCs were identified. HBO2 and lactate accelerated channel development, cell differentiation based on surface marker expression and cell cycle entry. CD34+ SPCs exhibited increases in thioredoxin 1 (Trx1), Trx reductase (TrxR), hypoxia inducible factors (HIF)-1, -2 and -3, phosphorylated mitogen activated protein kinases, vascular endothelial growth factor (VEGF) and stromal cell derived factor (SDF-1). Cell recruitment to Matrigel and protein synthesis responses were abrogated by N-acetyl cysteine, dithioerythritol, oxamate, apocynin, U0126, neutralizing anti-VEGF or anti-SDF-1 antibodies, and small inhibitory RNA to TrxR, lactate dehydrogenase, gp91[phox], HIF-1 or -2, and in mice conditionally null for HIF-1 in myeloid cells. By causing an oxidative stress, HBO2 activates a physiological redox-active autocrine loop in SPCs that stimulates vasculogenesis. Thioredoxin system activation leads to elevations in HIF-1 and -2 followed by synthesis of HIF-dependent growth factors. HIF-3 has a negative impact on SPCs.
