title: Endothelial cell-derived pentraxin 3 limits the vasoreparative therapeutic potential of circulating angiogenic cells.
abstract: Circulating angiogenic cells (CACs) promote revascularization of ischaemic tissues although their underlying mechanism of action and the consequences of delivering varying number of these cells for therapy remain unknown. This study investigates molecular mechanisms underpinning CAC modulation of blood vessel formation.
  
  
  
  CACs at low (2 × 105cells/mL) and mid (2 × 106cells/mL) cellular densities significantly enhanced endothelial cell tube formation in vitro, while high density (HD) CACs (2 × 107cells/mL) significantly inhibited this angiogenic process. In vivo, Matrigel-based angiogenesis assays confirmed mid-density CACs as pro-angiogenic and HD CACs as anti-angiogenic. Secretome characterization of CAC-EC conditioned media identified pentraxin 3 (PTX3) as only present in the HD CAC-EC co-culture. Recombinant PTX3 inhibited endothelial tube formation in vitro and in vivo. Importantly, our data revealed that the anti-angiogenic effect observed in HD CAC-EC co-cultures was significantly abrogated when PTX3 bioactivity was blocked using neutralizing antibodies or PTX3 siRNA in endothelial cells. We show evidence for an endothelial source of PTX3, triggered by exposure to HD CACs. In addition, we confirmed that PTX3 inhibits fibroblast growth factor (FGF) 2-mediated angiogenesis, and that the PTX3 N-terminus, containing the FGF-binding site, is responsible for such anti-angiogenic effects.
  
  
  
  Endothelium, when exposed to HD CACs, releases PTX3 which markedly impairs the vascular regenerative response in an autocrine manner. Therefore, CAC density and accompanying release of angiocrine PTX3 are critical considerations when using these cells as a cell therapy for ischaemic disease.
authors.affiliation: Centre for Experimental Medicine, School of Medicine, Dentistry, and Biomedical Science, Queen's University Belfast, Belfast BT12 6BA, UK.
authors.forename: Christina L
authors.initials: CL
authors.lastname: O'Neill
authors.affiliation: Centre for Experimental Medicine, School of Medicine, Dentistry, and Biomedical Science, Queen's University Belfast, Belfast BT12 6BA, UK.
authors.forename: Jasenka
authors.initials: J
authors.lastname: Guduric-Fuchs
authors.affiliation: Centre for Experimental Medicine, School of Medicine, Dentistry, and Biomedical Science, Queen's University Belfast, Belfast BT12 6BA, UK.
authors.forename: Sarah E J
authors.initials: SE
authors.lastname: Chambers
authors.affiliation: Centre for Experimental Medicine, School of Medicine, Dentistry, and Biomedical Science, Queen's University Belfast, Belfast BT12 6BA, UK.
authors.forename: Michelle
authors.initials: M
authors.lastname: O'Doherty
authors.affiliation: Humanitas Clinical and Research Centre, Rozzano 20089 Milan, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Bottazzi
authors.affiliation: Centre for Experimental Medicine, School of Medicine, Dentistry, and Biomedical Science, Queen's University Belfast, Belfast BT12 6BA, UK.
authors.forename: Alan W
authors.initials: AW
authors.lastname: Stitt
authors.affiliation: Centre for Experimental Medicine, School of Medicine, Dentistry, and Biomedical Science, Queen's University Belfast, Belfast BT12 6BA, UK r.medina@qub.ac.uk.
authors.forename: Reinhold J
authors.initials: RJ
authors.lastname: Medina
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D019898:Autocrine Communication; D002097:C-Reactive Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D018920:Coculture Techniques; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000378:metabolism*; D066026:Endothelial Progenitor Cells / Q000378:metabolism* / Q000637:transplantation; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D008875:Middle Aged; D018919:Neovascularization, Physiologic; D010100:Oxygen; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D034622:RNA Interference; D015861:Retinal Neovascularization; D012178:Retinopathy of Prematurity / Q000378:metabolism / Q000503:physiopathology / Q000601:surgery; D000683:Serum Amyloid P-Component / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection; D055815:Young Adult; D000099153:Pentraxins
chemical_list: D002097:C-Reactive Protein; D016207:Cytokines; D016222:Fibroblast Growth Factor 2; D018836:Inflammation Mediators; D010100:Oxygen; D000683:Serum Amyloid P-Component; D000099153:Pentraxins
keywords: Cell therapy; Circulating angiogenic cell; Ischaemia; PTX3; Vascular repair