title: Decline in platelet microparticles contributes to reduced hemostatic potential of stored plasma.
abstract: BACKGROUND
  In an effort to administer life-saving transfusions quickly, some trauma centers maintain thawed plasma (TP). According to AABB, TP is approved for transfusion for up to five days when stored at 1-6° C. However, the alterations in microparticles (MP) contained in the plasma, which are an integral component of plasma's hemostatic capacity, are not well characterized. We report on MP changes in TP between its initial thaw (FFP-0) and five days (FFP-5) of storage.
  
  
  METHODS
  FFP units (n=30) were thawed at 37° C and kept refrigerated for five days. Phenotypes of residual cells, which include platelets, erythrocytes, leukocytes, monocytes, endothelial cells, and MP counterparts of each cell type, were analyzed by flow cytometry. Functional assays were used for MP procoagulant activity, plasma thrombin generation, and clotting properties (thromboelastography).
  
  
  RESULTS
  In FFP-0 the majority (94%) of residual cells were platelets, along with significant levels of platelet MPs (4408 × 10(3)/L). FFP-5 showed a decline in MP count by 50% (p<0.0001), and procoagulant activity by 29% (p<0.0001). FFP-5 exhibited only 54% (p<0.0001) of the potential for thrombin generation as FFP-0, while thromboelastography indicated a slower clotting response (p<0.0001) and a longer delay in reaching maximum clot (p<0.01). Removal of MP by filtration resulted in reduced thrombin generation, while the MP replacement restored it.
  
  
  CONCLUSIONS
  Decline in MP with storage contributes to FFP-5's reduced ability to provide the hemostatic potential exhibited by FFP-0, suggesting the presence of platelet MPs in freshly TP may be beneficial and protective in the initial treatment of hemorrhage.
authors.affiliation: Center for Translational Injury Research and Department of Surgery, University of Texas Health Science Center at Houston, Houston, TX 77030, USA. nevenka.matijevic-aleksic@uth.tmc.edu
authors.forename: Nena
authors.initials: N
authors.lastname: Matijevic
authors.forename: Yao-Wei W
authors.initials: YW
authors.lastname: Wang
authors.forename: Vadim
authors.initials: V
authors.lastname: Kostousov
authors.forename: Charles E
authors.initials: CE
authors.lastname: Wade
authors.forename: K Vinod
authors.initials: KV
authors.lastname: Vijayan
authors.forename: John B
authors.initials: JB
authors.lastname: Holcomb
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001792:Blood Platelets; D001793:Blood Preservation; D055252:Cell-Derived Microparticles; D015925:Cryopreservation; D006487:Hemostasis; D006801:Humans; D008875:Middle Aged; D010314:Partial Thromboplastin Time; D010949:Plasma; D013916:Thrombelastography; D055815:Young Adult