title: p38 mitogen-activated protein kinase regulates mitochondrial function and microvesicle release in riboflavin- and ultraviolet light-treated apheresis platelet concentrates.
abstract: Biochemical analyses of mechanisms triggered in platelets (PLTs) upon pathogen inactivation (PI) are crucial to further understand the impact of PI on PLT functionality and, subsequently, quality.
  
  
  
  PLT concentrates (PCs) were split into four small illumination bags: 1) untreated control, 2) treated with riboflavin and ultraviolet light (RF/UV), and spiked with 3) solvent control dimethyl sulfoxide and 4) p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580 before RF/UV treatment. Flow cytometry was used to monitor PLT mitochondrial potential (ΔΨm); generation of intracellular reactive oxygen species (ROS); and release of microvesicles (MVs), mitochondria (MT), and MVs containing MT (MVs/MT). Quantitative polymerase chain reaction (qPCR) was used to quantify extracellular mitochondrial DNA (mtDNA). Translocation of selected mitochondrial proteins was analyzed in subcellular fractions by immunoblot.
  
  
  
  RF/UV treatment triggered an increased mitochondrial translocation of both Bax and Bid (p < 0.05, Day 7) and cytochrome c release (p < 0.01, Day 7), loss of ΔΨm(p < 0.05, Day 5 and Day 7), and ROS generation (p < 0.01, Day 5 and Day 7) in PCs compared to the untreated control during storage. These PI-triggered changes were inhibited by SB203580 (p < 0.05). The release of MVs, MT, and MVs/MT was increased upon the RF/UV treatment during storage (p < 0.05) and, with the exception of MT, the release was decreased by the inhibitor (p < 0.05). qPCR analysis showed that RF/UV does not trigger mtDNA release during storage.
  
  
  
  These findings further our understanding of mechanisms in PLTs initiated by the RF/UV treatment, demonstrating that this treatment induces p38 MAPK-dependent mitochondrial signaling and MV release in apheresis PCs.
authors.affiliation: Centre for Innovation, Canadian Blood Services, Vancouver, British Columbia, Canada.|Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Zhongming
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Centre for Innovation, Canadian Blood Services, Vancouver, British Columbia, Canada.|Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada.|Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Peter
authors.initials: P
authors.lastname: Schubert
authors.affiliation: Blood Systems Research Institute, University of California, San Francisco, California.
authors.forename: Sonia
authors.initials: S
authors.lastname: Bakkour
authors.affiliation: Centre for Innovation, Canadian Blood Services, Vancouver, British Columbia, Canada.|Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Brankica
authors.initials: B
authors.lastname: Culibrk
authors.affiliation: Blood Systems Research Institute, University of California, San Francisco, California.|Department of Laboratory Medicine, University of California, San Francisco, California.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Busch
authors.affiliation: Centre for Innovation, Canadian Blood Services, Vancouver, British Columbia, Canada.|Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada.|Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Dana V
authors.initials: DV
authors.lastname: Devine
mesh_terms: D001792:Blood Platelets / Q000187:drug effects / Q000201:enzymology* / Q000528:radiation effects / Q000648:ultrastructure; D055252:Cell-Derived Microparticles / Q000378:metabolism; D006801:Humans; D020935:MAP Kinase Signaling System; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology / Q000502:physiology* / Q000528:radiation effects; D010983:Plateletpheresis / Q000379:methods*; D017382:Reactive Oxygen Species; D012256:Riboflavin / Q000494:pharmacology*; D014466:Ultraviolet Rays; D048051:p38 Mitogen-Activated Protein Kinases / Q000502:physiology*
chemical_list: D017382:Reactive Oxygen Species; D048051:p38 Mitogen-Activated Protein Kinases; D012256:Riboflavin