title: PAR1-stimulated platelet releasate promotes angiogenic activities of endothelial progenitor cells more potently than PAR4-stimulated platelet releasate.
abstract: BACKGROUND
  Endothelial progenitor cells (EPCs) are important for endothelial regeneration and angiogenesis. Thrombin protease-activated receptor 1 (PAR1) PAR1 and PAR4 stimulation induces selective release of platelet proangiogenic and antiangiogenic regulators.
  
  
  OBJECTIVE
  To investigate if PAR1-stimulated platelet releasate (PAR1-PR) and PAR4-PR regulate angiogenic properties of EPCs in different manners.
  
  
  RESULTS
  EPCs were generated from peripheral mononuclear cell culture. Washed platelets (2 × 10(9) mL(-1)) were stimulated by PAR1-activating peptide (PAR1-AP; 10 μmol L(-1)) or PAR4-AP (100 μmol L(-1)) to prepare PAR1-PR and PAR4-PR, respectively. PAR1-PR or PAR4-PR had little influence on EPC proliferation. EPC migration experiments using a modified Boyden chamber showed that both platelet releasates facilitated EPC migration. As for in vitro tube formation on Matrigel, PAR1-PR and PAR4-PR similarly enhanced capillary-like network formation of EPCs in the complete EPC medium containing 10% FBS and a cocktail of growth factors, while PAR1-PR more profoundly increased EPC tube formation in basal culture medium supplemented with only 0.5% FBS than did PAR4-PR. The latter was confirmed in the murine angiogenesis model of subcutaneous Matrigel implantation. Moreover, blockade of vascular endothelial growth factor, stromal cell-derived factor 1α, or matrix metalloproteinases attenuated EPC migration and tube formation, suggesting a cooperation of these factors in the enhancements.
  
  
  CONCLUSIONS
  PAR1-PR enhances vasculogenesis more potently than PAR4-PR, and the enhancements require a cooperation of multiple platelet-derived angiogenic regulators.
authors.affiliation: Clinical Pharmacology Unit, Department of Medicine-Solna, Karolinska Institutet, Karolinska University Hospital-Solna, Stockholm, Sweden.
authors.forename: Z
authors.initials: Z
authors.lastname: Huang
authors.forename: X
authors.initials: X
authors.lastname: Miao
authors.forename: Y
authors.initials: Y
authors.lastname: Luan
authors.forename: L
authors.initials: L
authors.lastname: Zhu
authors.forename: F
authors.initials: F
authors.lastname: Kong
authors.forename: Q
authors.initials: Q
authors.lastname: Lu
authors.forename: J
authors.initials: J
authors.lastname: Pernow
authors.forename: G
authors.initials: G
authors.lastname: Nilsson
authors.forename: N
authors.initials: N
authors.lastname: Li
mesh_terms: D000328:Adult; D020533:Angiogenesis Inhibitors / Q000494:pharmacology; D042501:Angiogenic Proteins / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002465:Cell Movement; D049109:Cell Proliferation; D002478:Cells, Cultured; D054377:Chemokine CXCL12 / Q000378:metabolism; D066026:Endothelial Progenitor Cells / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D020782:Matrix Metalloproteinases / Q000378:metabolism; D008810:Mice, Inbred C57BL; D008875:Middle Aged; D023421:Models, Animal; D018919:Neovascularization, Physiologic / Q000187:drug effects; D019899:Paracrine Communication / Q000187:drug effects; D010455:Peptides / Q000494:pharmacology; D044463:Receptor, PAR-1 / Q000819:agonists / Q000378:metabolism*; D018179:Receptors, Thrombin / Q000819:agonists / Q000378:metabolism*; D015398:Signal Transduction; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D055815:Young Adult
chemical_list: D020533:Angiogenesis Inhibitors; D042501:Angiogenic Proteins; C515255:CXCL12 protein, human; D054377:Chemokine CXCL12; D010455:Peptides; D044463:Receptor, PAR-1; D018179:Receptors, Thrombin; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D020782:Matrix Metalloproteinases; C112908:protease-activated receptor 4
keywords: angiogenesis modulators; endothelial progenitor cells; platelets; stem cells; thrombin