title: Analysis of platelet-derived extracellular vesicles in plateletpheresis concentrates: a multicenter study.
abstract: Routine quantification of platelet-derived extracellular vesicles (PL-EVs) may be useful in the quality control (QC) of platelet concentrates (PCs). The aim of this multicenter study was to establish and validate a consensus protocol for the standardized PL-EV quantification using conventional flow cytometers.
  
  
  
  Eighty-six PCs were investigated in five blood transfusion centers (A-E) on Days 0 and 5. The centers used different apheresis instruments: Trima Accel (n = 56) and/or Amicus (n = 30). PCs were prepared using standard methods (sd-PCs; n = 73; A-D) or with pathogen inactivation (PI [PI-PCs]; n = 13; E). Platelet (PLT) count was determined using conventional hematology analyzers. PLT degranulation (P-selectin expression in response to thrombin receptor PAR1 activation) and PL-EVs were analyzed by flow cytometry.
  
  
  
  During storage, PLT count remained stable in 58 PCs (A, C, E), whereas a decrease was observed in 12 PCs (B). PLT degranulation declined in all PCs (p < 0.001) and PL-EVs increased in 74 PCs (A, C-E; p < 0.001). Certain donor variables (e.g., plasma cholesterol, immature PLT fraction) were associated with lower PL-EVs. In Trima-produced PCs, PL-EVs were significantly lower (D) and PLT degranulation was superior compared to PCs prepared with the Amicus (A, D). PL-EVs were 10-fold lower in PI-PCs, compared to sd-PCs. However, similar QC trends were demonstrated for both PC groups during storage.
  
  
  
  PL-EV analysis in a QC program of PCs was successfully performed with results comparable among the different centers. PLT degranulation and vesiculation were primarily affected by preparation techniques.
authors.affiliation: Institute for Clinical Chemistry and Laboratory Medicine, University Hospital of Regensburg, Regensburg, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Black
authors.affiliation: Institute for Clinical Chemistry and Laboratory Medicine, University Hospital of Regensburg, Regensburg, Germany.
authors.forename: Evelyn
authors.initials: E
authors.lastname: Orsó
authors.affiliation: Institute of Transfusion Medicine and Transplantation Immunology, University Hospital Muenster, Muenster, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Kelsch
authors.affiliation: Institute of Transfusion Medicine, Charité University Medical Centre, Berlin, Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: Pereira
authors.affiliation: Institute of Transfusion Medicine, Charité University Medical Centre, Berlin, Germany.
authors.forename: Julian
authors.initials: J
authors.lastname: Kamhieh-Milz
authors.affiliation: Institute of Transfusion Medicine, Charité University Medical Centre, Berlin, Germany.
authors.forename: Abdulgabar
authors.initials: A
authors.lastname: Salama
authors.affiliation: Department for Health Sciences and Biomedicine, Danube University Krems, Krems, Austria.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Fischer
authors.affiliation: Regional Blood Transfusion Service Zurich SRK, Zurich, Switzerland.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Meyer
authors.affiliation: Regional Blood Transfusion Service Zurich SRK, Zurich, Switzerland.
authors.forename: Beat M
authors.initials: BM
authors.lastname: Frey
authors.affiliation: Institute for Clinical Chemistry and Laboratory Medicine, University Hospital of Regensburg, Regensburg, Germany.
authors.forename: Gerd
authors.initials: G
authors.lastname: Schmitz
mesh_terms: D001792:Blood Platelets / Q000378:metabolism*; D000067128:Extracellular Vesicles / Q000378:metabolism*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D008297:Male; D010983:Plateletpheresis; D011786:Quality Control