title: Vesicles generated during storage of red cells are rich in the lipid raft marker stomatin.
abstract: BACKGROUND
  The release of vesicles by red blood cells (RBCs) occurs in vivo and in vitro under various conditions. Vesiculation also takes place during RBC storage and results in the accumulation of vesicles in RBC units. The membrane protein composition of the storage-associated vesicles has not been studied in detail. The characterization of the vesicular membrane might hint at the underlying mechanism of the storage-associated changes in general and the vesiculation process in particular.
  
  
  METHODS
  Vesicles from RBCs that had been stored for various periods were isolated and RBCs of the same RBC units were used to generate calcium-induced microvesicles. These two vesicle types were compared with respect to their size with atomic force microscopy, their raft protein content with detergent-resistant membrane (DRM) analysis, and their thrombogenic potential and activity with annexin V binding and thrombin generation, respectively.
  
  
  RESULTS
  The storage-associated vesicles and the calcium-induced microvesicles are similar in size, in thrombogenic activity, and in membrane protein composition. The major differences were the relative concentrations of the major integral DRM proteins. In storage-associated vesicles, stomatin is twofold enriched and flotillin-2 is threefold depleted.
  
  
  CONCLUSIONS
  These data indicate that a stomatin-specific, raft-based process is involved in storage-associated vesiculation. A model of the vesiculation process in RBCs is proposed considering the raft-stabilizing properties of stomatin, the low storage temperature favoring raft aggregation, and the previously reported storage-associated changes in the cytoskeletal organization.
authors: Department of Vascular Biology and Thrombosis Research, Medical University of Vienna, Vienna, Austria. ulrich.salzer@meduniwien.ac.at
authors: Ulrich
authors: U
authors: Salzer
authors: Rong
authors: R
authors: Zhu
authors: Marleen
authors: M
authors: Luten
authors: Hirotaka
authors: H
authors: Isobe
authors: Vassili
authors: V
authors: Pastushenko
authors: Thomas
authors: T
authors: Perkmann
authors: Peter
authors: P
authors: Hinterdorfer
authors: Giel J C G M
authors: GJ
authors: Bosman
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000465:Algorithms; D001793:Blood Preservation / Q000379:methods; D022162:Cytoplasmic Vesicles / Q000378:metabolism*; D004912:Erythrocytes / Q000166:cytology / Q000378:metabolism*; D005434:Flow Cytometry; D005947:Glucose / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D021962:Membrane Microdomains / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D018625:Microscopy, Atomic Force; D012964:Sodium / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; C036860:STOM protein, human; D000255:Adenosine Triphosphate; D012964:Sodium; D005947:Glucose