title: Angiogenic microvascular endothelial cells release microparticles rich in tissue factor that promotes postischemic collateral vessel formation.
abstract: OBJECTIVE
  Therapeutic angiogenesis is a promising strategy for treating ischemia. Our previous work showed that endogenous endothelial tissue factor (TF) expression induces intracrine signaling and switches-on angiogenesis in microvascular endothelial cells (mECs). We have hypothesized that activated mECs could exert a further paracrine regulation through the release of TF-rich microvascular endothelial microparticles (mEMPs) and induce neovascularization of ischemic tissues.
  
  
  RESULTS
  Here, we describe for the first time that activated mECs are able to induce reparative neovascularization in ischemic zones by releasing TF-rich microparticles. We show in vitro and in vivo that mEMPs released by both wild-type and TF-upregulated-mECs induce angiogenesis and collateral vessel formation, whereas TF-poor mEMPs derived from TF-silenced mECs are not able to trigger angiogenesis. Isolated TF-bearing mEMPs delivered to nonperfused adductor muscles in a murine hindlimb ischemia model enhance collateral flow and capillary formation evidenced by MRI. TF-bearing mEMPs increase angiogenesis operating via paracrine regulation of neighboring endothelial cells, signaling through the β1-integrin pathway Rac1-ERK1/2-ETS1 and triggering CCL2 (chemokine [C-C motif] ligand 2) production to form new and competent mature neovessels.
  
  
  CONCLUSIONS
  These findings demonstrate that TF-rich mEMPs released by microvascular endothelial cells can overcome the consequences of arterial occlusion and tissue ischemia by promoting postischemic neovascularization and tissue reperfusion.
authors.affiliation: From the Cardiovascular Research Center (CSIC-ICCC), IIB-Sant Pau and Hospital de Sant Pau, Barcelona, Spain (G.A., E.P., L.B.); and Cardiovascular Research Chair Universitat Autònoma de Barcelona, Barcelona, Spain (L.B.).
authors.forename: Gemma
authors.initials: G
authors.lastname: Arderiu
authors.affiliation: From the Cardiovascular Research Center (CSIC-ICCC), IIB-Sant Pau and Hospital de Sant Pau, Barcelona, Spain (G.A., E.P., L.B.); and Cardiovascular Research Chair Universitat Autònoma de Barcelona, Barcelona, Spain (L.B.).
authors.forename: Esther
authors.initials: E
authors.lastname: Peña
authors.affiliation: From the Cardiovascular Research Center (CSIC-ICCC), IIB-Sant Pau and Hospital de Sant Pau, Barcelona, Spain (G.A., E.P., L.B.); and Cardiovascular Research Chair Universitat Autònoma de Barcelona, Barcelona, Spain (L.B.). lbadimon@csic-iccc.org.
authors.forename: Lina
authors.initials: L
authors.lastname: Badimon
mesh_terms: D000818:Animals; D002460:Cell Line; D055252:Cell-Derived Microparticles / Q000378:metabolism / Q000473:pathology / Q000637:transplantation*; D003097:Collateral Circulation; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000378:metabolism / Q000473:pathology / Q000637:transplantation*; D006614:Hindlimb; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism; D007511:Ischemia / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D018810:Magnetic Resonance Angiography; D008297:Male; D008819:Mice, Nude; D055806:Microvessels / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000378:metabolism* / Q000473:pathology; D018919:Neovascularization, Physiologic; D019899:Paracrine Communication; D034622:RNA Interference; D015398:Signal Transduction; D013925:Thromboplastin / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D046509:Tissue Culture Techniques; D014162:Transfection
chemical_list: D019012:Integrin beta1; D013925:Thromboplastin
keywords: angiogenesis-inducing agents; cell-derived microparticles; endothelial cells; hindlimb ischemia; thromboplastin