title: Small-size circulating microparticles in acute coronary syndromes: relevance to fibrinolytic status, reparative markers and outcomes.
abstract: BACKGROUND
  Recent evidence suggests that circulating microparticles (MPs) contribute to inflammation, coagulation and vascular injury. Majority of MPs have usually not been included into prior analyses due their small size and limited resolution of conventional equipment. Our aim was to assess levels of MPs of different cellular origin sized below 0.5 μm polystyrene beads, denoted as small-size microparticles (sMP), their relation to markers of cardiovascular repair and their impact on prognosis in patients with acute coronary syndromes (ACS).
  
  
  METHODS
  In a cross-sectional study, we initially compared levels of sMP between patients with ST-segment elevation myocardial infarction (STEMI, n = 50), non-STEMI (n = 47), stable coronary artery disease (CAD, n = 40) and healthy individuals (HC, n = 40). In a separate study, the prognostic value of sMP was assessed in patients with non-STEMI (n = 160). Annexin V-binding sMP (sAMP), platelet CD42b(+) sMPs (sPMP), endothelial CD144(+) sMP (sEMP) and monocyte CD14(+) sMP (sMMP) were quantified using high resolution flow cytometry. Endothelial progenitor cells (EPCs) and monocyte expression of scavenger receptors was quantified by flow cytometry. Fibrinolytic factors were measured by ELISA.
  
  
  RESULTS
  Counts of sAMP and sEMP were lower in STEMI after PCI (p < 0.001 and p = 0.025, respectively) but not in non-STEMI vs. CAD. sAMP was positively correlated with EPCs in non-STEMI (p < 0.001). Likewise, plasminogen activators negatively correlated with sAMP in non-STEMI and STEMI (p = 0.02 and p = 0.002, respectively). In non-STEMI patients, sEMP and sMMP were independently predictive for future admissions related to heart failure (p = 0.034 and 0.013, respectively) and sPMP for major bleedings (p = 0.002). The sAMP/EPCs ratio was higher in patients (before PCI) compared to STEMI patients.
  
  
  CONCLUSIONS
  Small-size MPs could be potentially implicated in the modulation of the post-ACS reparative response to injury, with prognostic implications. Besides, the sAMP/EPCs ratio could reflect a change in the apoptotic/reparative potential, being a putative indicator for vascular repair.
authors: University of Birmingham Centre for Cardiovascular Sciences, City Hospital, Birmingham B18 7QH, UK.
authors: Silvia
authors: S
authors: Montoro-García
authors: Eduard
authors: E
authors: Shantsila
authors: Luke D
authors: LD
authors: Tapp
authors: Angel
authors: A
authors: López-Cuenca
authors: Ana Isabel
authors: AI
authors: Romero
authors: Diana
authors: D
authors: Hernández-Romero
authors: Esteban
authors: E
authors: Orenes-Piñero
authors: Sergio
authors: S
authors: Manzano-Fernández
authors: Mariano
authors: M
authors: Valdés
authors: Francisco
authors: F
authors: Marín
authors: Gregory Y H
authors: GY
authors: Lip
mesh_terms: D054058:Acute Coronary Syndrome / Q000097:blood* / Q000175:diagnosis; D000368:Aged; D017304:Annexin A5 / Q000494:pharmacology; D015703:Antigens, CD / Q000378:metabolism; D001792:Blood Platelets / Q000166:cytology; D015820:Cadherins / Q000378:metabolism; D055252:Cell-Derived Microparticles / Q000473:pathology*; D003324:Coronary Artery Disease / Q000097:blood / Q000175:diagnosis; D003430:Cross-Sectional Studies; D005260:Female; D005342:Fibrinolysis; D006801:Humans; D007249:Inflammation; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000166:cytology; D009203:Myocardial Infarction / Q000097:blood / Q000175:diagnosis; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000378:metabolism; D011379:Prognosis; D013234:Stem Cells / Q000166:cytology; D016896:Treatment Outcome; D000099152:Cadherin 5
chemical_list: D017304:Annexin A5; D015703:Antigens, CD; D015820:Cadherins; D019038:Platelet Glycoprotein GPIb-IX Complex; D000099152:Cadherin 5