title: Pathogen reduction treatment using riboflavin and ultraviolet light impairs platelet reactivity toward specific agonists in vitro.
abstract: BACKGROUND
  Recent studies showed that Mirasol pathogen reduction treatment (PRT) leads to increased P-selectin expression and increased oxygen and glucose consumption in resting platelets (PLTs). This study investigates the effect of PRT on PLT activation.
  
  
  METHODS
  Untreated or Mirasol-treated PLTs were analyzed at different time points during storage. Microaggregation upon stimulation with phorbol myristate acetate (PMA), convulxin, and ristocetin was measured. Alpha granule contents and release upon thrombin stimulation were assessed by flow cytometry and Western blotting. PLT spreading was determined on collagen-coated glass slides.
  
  
  RESULTS
  Mirasol PRT led to spontaneous aggregation (hyperreactivity), as measured by flow cytometry in the absence of agonist throughout storage time. PMA-induced aggregation was significantly higher in Mirasol PRT PLTs compared to controls. Aggregation in response to convulxin and ristocetin was significantly lower and directly influenced by storage time after Mirasol PRT, compared to untreated stored PLT concentrates. Despite the reported hyperreactivity of resting PLTs, PLT activation with thrombin on Day 8 after Mirasol PRT resulted in less P-selectin-positive PLTs. Furthermore, platelet factor 4 (PF4) secretion was reduced upon thrombin stimulation on Day 8 after PRT compared to controls. Significantly decreased spreading of Mirasol PRT PLTs over collagen-coated slides was observed directly after PRT and persisted throughout storage.
  
  
  CONCLUSIONS
  Mirasol PRT leads to hyperreactive PLTs, probably caused by continuous basal degranulation through storage time. This results in a reduction in the degranulation capacity upon acute stimulation, which influences PLT spreading, but not overtly microaggregation. The clinical relevance needs to be investigated.
authors.affiliation: Department of Hematopoiesis, University of Amsterdam, Amsterdam, the Netherlands.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Zeddies
authors.forename: Iris M
authors.initials: IM
authors.lastname: De Cuyper
authors.forename: Pieter F
authors.initials: PF
authors.lastname: van der Meer
authors.forename: Brunette B
authors.initials: BB
authors.lastname: Daal
authors.forename: Dirk
authors.initials: D
authors.lastname: de Korte
authors.forename: Laura
authors.initials: L
authors.lastname: Gutiérrez
authors.forename: Daphne C
authors.initials: DC
authors.lastname: Thijssen-Timmer
mesh_terms: D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects*; D001793:Blood Preservation / Q000379:methods; D003094:Collagen / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D015539:Platelet Activation / Q000187:drug effects / Q000528:radiation effects; D017713:Platelet Transfusion; D012256:Riboflavin / Q000494:pharmacology*; D014466:Ultraviolet Rays
chemical_list: D003094:Collagen; D012256:Riboflavin