title: Refrigerated storage of platelets initiates changes in platelet surface marker expression and localization of intracellular proteins.
abstract: BACKGROUND
  Platelets (PLTs) are currently stored at room temperature (22°C), which limits their shelf life, primarily due to the risk of bacterial growth. Alternatives to room temperature storage include PLT refrigeration (2-6°C), which inhibits bacterial growth, thus potentially allowing an extension of shelf life. Additionally, refrigerated PLTs appear more hemostatically active than conventional PLTs, which may be beneficial in certain clinical situations. However, the mechanisms responsible for this hemostatic function are not well characterized. The aim of this study was to assess the protein profile of refrigerated PLTs in an effort to understand these functional consequences.
  
  
  METHODS
  Buffy coat PLTs were pooled, split, and stored either at room temperature (20-24°C) or under refrigerated (2-6°C) conditions (n = 8 in each group). PLTs were assessed for changes in external receptor expression and actin filamentation using flow cytometry. Intracellular proteomic changes were assessed using two-dimensional gel electrophoresis and Western blotting.
  
  
  RESULTS
  PLT refrigeration significantly reduced the abundance of glycoproteins (GPIb, GPIX, GPIIb, and GPIV) on the external membrane. However, refrigeration resulted in the increased expression of high-affinity integrins (αIIbβ3 and β1) and activation and apoptosis markers (CD62P, CD63, and phosphatidylserine). PLT refrigeration substantially altered the abundance and localization of several cytoskeletal proteins and resulted in an increase in actin filamentation, as measured by phalloidin staining.
  
  
  CONCLUSIONS
  Refrigerated storage of PLTs induces significant changes in the expression and localization of both surface-expressed and intracellular proteins. Understanding these proteomic changes may help to identify the mechanisms resulting in the refrigeration-associated alterations in PLT function and clearance.
authors.affiliation: Research & Development, Australian Red Cross Blood Service, Alexandria, NSW, Australia.|Proteomics Core Facility, University of Technology Sydney, Sydney, NSW, Australia.
authors.forename: Ben
authors.initials: B
authors.lastname: Wood
authors.affiliation: Proteomics Core Facility, University of Technology Sydney, Sydney, NSW, Australia.
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Padula
authors.affiliation: Research & Development, Australian Red Cross Blood Service, Alexandria, NSW, Australia.
authors.forename: Denese C
authors.initials: DC
authors.lastname: Marks
authors.affiliation: Research & Development, Australian Red Cross Blood Service, Alexandria, NSW, Australia. ljohnson@redcrossblood.org.au.
authors.forename: Lacey
authors.initials: L
authors.lastname: Johnson
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D001792:Blood Platelets / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism; D001793:Blood Preservation / Q000379:methods*; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D040901:Proteomics / Q000379:methods; D011956:Receptors, Cell Surface / Q000378:metabolism; D012034:Refrigeration
chemical_list: D006023:Glycoproteins; D011956:Receptors, Cell Surface