title: Platelet microparticles enhance the vasoregenerative potential of angiogenic early outgrowth cells after vascular injury.
abstract: BACKGROUND
  Angiogenic early outgrowth cells (EOCs) have been reported to contribute to endothelial regeneration and to limit neointima formation after vascular injury. Vascular pathologies comprise platelet activation and concomitant generation of platelet microparticles (PMPs). We hypothesized that PMPs may interact with EOCs in the context of vascular injury and modulate their regenerative potential.
  
  
  RESULTS
  Using flow cytometry, confocal microscopy, and scanning electron microscopy, we demonstrated the binding of thrombin/collagen-induced PMPs to EOCs with subsequent membrane assimilation and incorporation. This interaction promoted phenotypic alterations of EOCs with increased expression of endothelial cell markers and transfer of the chemokine receptor CXCR4 to EOCs with enhanced responsiveness to its ligand CXCL12/SDF-1alpha. In addition, PMPs augmented the adhesion of EOCs to extracellular matrix components and to the injured vessel wall and accelerated cytoskeletal reorganization and migration of EOCs. PMPs induced changes in the EOC secretome toward a more proangiogenic profile and amplified the EOC-mediated induction of proliferation, migration, and capillary tube formation by mature endothelial cells. Compared with untreated EOCs, the injection of PMP-treated EOCs resulted in accelerated reendothelialization after arterial denudation injury in athymic nude mice, whereas the EOC-mediated reduction of neointima formation remained unchanged.
  
  
  CONCLUSIONS
  Our data provide evidence that PMPs can boost the potential of EOCs to restore endothelial integrity after vascular injury. Major mechanisms involve the enhancement of EOC recruitment, migration, differentiation, and release of proangiogenic factors.
authors.affiliation: Medical Faculty, Institute for Molecular Cardiovascular Research, RWTH Aachen University, Aachen, Germany.
authors.forename: Sebastian F
authors.initials: SF
authors.lastname: Mause
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Ritzel
authors.forename: Elisa A
authors.initials: EA
authors.lastname: Liehn
authors.forename: Mihail
authors.initials: M
authors.lastname: Hristov
authors.forename: Kiril
authors.initials: K
authors.lastname: Bidzhekov
authors.forename: Gerhard
authors.initials: G
authors.lastname: Müller-Newen
authors.forename: Oliver
authors.initials: O
authors.lastname: Soehnlein
authors.forename: Christian
authors.initials: C
authors.lastname: Weber
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001792:Blood Platelets / Q000166:cytology / Q000502:physiology*; D002339:Carotid Arteries / Q000473:pathology / Q000502:physiology; D020212:Carotid Artery Injuries / Q000473:pathology / Q000503:physiopathology*; D002450:Cell Communication / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D055252:Cell-Derived Microparticles / Q000502:physiology*; D002478:Cells, Cultured; D054377:Chemokine CXCL12 / Q000378:metabolism; D003599:Cytoskeleton / Q000502:physiology; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000166:cytology / Q000502:physiology*; D005434:Flow Cytometry; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D018919:Neovascularization, Physiologic / Q000502:physiology*; D019718:Receptors, CXCR4 / Q000378:metabolism; D012038:Regeneration / Q000502:physiology; D014471:Umbilical Veins / Q000166:cytology
chemical_list: D015415:Biomarkers; C515255:CXCL12 protein, human; C527276:CXCR4 protein, human; D054377:Chemokine CXCL12; D019718:Receptors, CXCR4