COMP-Ang1 stimulates HIF-1α-mediated SDF-1 overexpression and recovers ischemic injury through BM-derived progenitor cell recruitment

Blood. 2011 Apr 21;117(16):4376-86. doi: 10.1182/blood-2010-07-295964. Epub 2011 Jan 3.

Abstract

Recruitment and adhesion of bone marrow (BM)-derived circulating progenitor cells to ischemic tissue are important for vasculogenesis and tissue repair. Recently, we found cartilage oligomeric matrix protein (COMP)-Ang1 is a useful cell-priming agent to improve the therapeutic efficacy of progenitor cells. However, the effect and the underlying mechanisms of COMP-Ang1 on recruitment of BM-derived progenitor cells (BMPCs) to foci of vascular injury have not been well defined. Here, we found that COMP-Ang1 is a critical stimulator of stromal cell-derived factor 1 (SDF-1), the principal regulator of BM-cell trafficking. Furthermore, SDF-1 stimulation by COMP-Ang1 was blocked by small-interfering RNA (siRNA) against hypoxia-inducible factor-1α (HIF-1α). COMP-Ang1 increased the synthesis of HIF-1α by activating mammalian target of rapamycin (mTOR) in hypoxic endothelium. The intermediate mechanism transmitting the COMP-Ang1 signal to the downstream mTOR/HIF-1α/SDF-1 pathway was the enhanced binding of the Tie2 receptor with integrin-linked kinase (ILK), an upstream activator of mTOR. In the mouse ischemic model, local injection of COMP-Ang1 stimulated the incorporation of BMPCs into ischemic limb, thereby enhancing neovasculogenesis and limb salvage. Collectively, our findings identify the COMP-Ang1/HIF-1α/SDF-1 pathway as a novel inducer of BMPC recruitment and neovasculogenesis in ischemic disease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bone Marrow Cells / cytology*
  • Bone Marrow Cells / metabolism
  • Cell Hypoxia / drug effects*
  • Cell Movement
  • Cells, Cultured
  • Chemokine CXCL12 / genetics*
  • Chemokine CXCL12 / metabolism
  • Female
  • Humans
  • Hypoxia / drug therapy*
  • Hypoxia / metabolism*
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism*
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Recombinant Fusion Proteins / metabolism
  • Recombinant Fusion Proteins / therapeutic use*
  • Stem Cells / cytology*
  • Stem Cells / metabolism
  • TOR Serine-Threonine Kinases / metabolism
  • Up-Regulation

Substances

  • COMP-Ang1 fusion protein
  • Chemokine CXCL12
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Recombinant Fusion Proteins
  • TOR Serine-Threonine Kinases