NADPH Oxidase 2 Regulates Bone Marrow Microenvironment Following Hindlimb Ischemia: Role in Reparative Mobilization of Progenitor Cells§

Authors

  • Norifumi Urao,

    1. Department of Pharmacology, Center for Lung and Vascular Biology, University of Illinois at Chicago, Chicago, Illinois, USA
    2. Center for Cardiovascular Research, University of Illinois at Chicago, Chicago, Illinois, USA
    Search for more papers by this author
  • Ronald D. McKinney,

    1. Department of Pharmacology, Center for Lung and Vascular Biology, University of Illinois at Chicago, Chicago, Illinois, USA
    2. Center for Cardiovascular Research, University of Illinois at Chicago, Chicago, Illinois, USA
    Search for more papers by this author
  • Tohru Fukai,

    1. Center for Cardiovascular Research, University of Illinois at Chicago, Chicago, Illinois, USA
    2. Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA
    3. Department of Pharmacology, University of Illinois at Chicago, Chicago, Illinois, USA
    Search for more papers by this author
  • Masuko Ushio-Fukai

    Corresponding author
    1. Department of Pharmacology, Center for Lung and Vascular Biology, University of Illinois at Chicago, Chicago, Illinois, USA
    2. Center for Cardiovascular Research, University of Illinois at Chicago, Chicago, Illinois, USA
    • Department of Pharmacology, Center for Lung and Vascular Biology, Center for Cardiovascular Research, University of Illinois at Chicago, 835 S. Wolcott, M/C868, E403 MSB, Chicago, Illinois 60612, USA
    Search for more papers by this author
    • Telephone: 312-996-7665; Fax: 312-996-1225


  • Author contributions: N.U.: conception and design, financial support, collection and/or assembly of data, data analysis and interpretation, manuscript writing, and final approval of manuscript; R.D.M.: administrative support, collection of data, provision of study material, and final approval of manuscript; T.F.: financial support, data analysis and interpretation, and final approval of manuscript; M.U.: financial support, conception and design, data analysis and interpretation, manuscript writing, and final approval of manuscript.

  • Disclosure of potential conflicts of interest is found at the end of this article.

  • §

    First published online in STEM CELLSEXPRESS January 30, 2012.

Abstract

Bone marrow (BM) microenvironment, which is regulated by hypoxia and proteolytic enzymes, is crucial for stem/progenitor cell function and mobilization involved in postnatal neovascularization. We demonstrated that NADPH oxidase 2 (Nox2)-derived reactive oxygen species (ROS) are involved in postischemic mobilization of BM cells and revascularization. However, role of Nox2 in regulating BM microenvironment in response to ischemic injury remains unknown. Here, we show that hindlimb ischemia of mice increases ROS production in both the endosteal and central region of BM tissue in situ, which is almost completely abolished in Nox2 knockout (KO) mice. This Nox2-dependent ROS production is mainly derived from Gr-1+ myeloid cells in BM. In vivo injection of hypoxyprobe reveals that endosteum at the BM is hypoxic with high expression of hypoxia-inducible factor-1α in basal state. Following hindlimb ischemia, hypoxic areas and HIF-1α expression are expanded throughout the BM, which is inhibited in Nox2 KO mice. This ischemia-induced alteration of Nox2-dependent BM microenvironment is associated with an increase in vascular endothelial growth factor expression and Akt phosphorylation in BM tissue, thereby promoting Lin progenitor cell survival and expansion, leading to their mobilization from BM. Furthermore, hindlimb ischemia increases proteolytic enzymes membrane type 1-matrix metalloproteinase (MMP) expression and MMP-9 activity in BM, which is inhibited in Nox2 KO mice. In summary, Nox2-dependent increase in ROS plays a critical role in regulating hypoxia expansion and proteolytic activities in BM microenvironment in response to tissue ischemia. This in turn promotes progenitor cell expansion and reparative mobilization from BM, leading to postischemic neovascularization and tissue repair. STEM CELLS 2012;30:923–934

Ancillary