title: Novel method to leukoreduce murine blood for transfusion: how to reduce animal usage.
abstract: BACKGROUND
  Basic research on the pathomechanisms of transfusion-related adverse events depends on murine transfusion models, in which leukoreduction (LR) is a prevalent standard. The commonly used neonatal LR filter (LRF) is associated with considerable animal numbers. A more efficient method would help support the guiding principles of "replacement, reduction, refinement" (3Rs).
  
  
  METHODS
  Blood from C57BL/6 and C57BL/6-Tg(UBC-GFP)30Scha/J mice was leukoreduced using (1) a neonatal LRF, (2) a syringe LRF, or (3) CD45 microbeads. Product quality was assessed according to US Food and Drug Administration (FDA) standards. White blood cell numbers were analyzed by flow cytometry; hemoglobin concentrations and hematocrit were measured and in vivo posttransfusion recoveries were determined after 2 weeks of storage.
  
  
  RESULTS
  Using the neonatal filter, a LR of 99.56% was achieved with wastage of 12.4 mL in comparison to 99.68% and 1-mL hold-up volume with the syringe filter and 99.11 ± 0.24% LR and 0.1-mL wastage using microbeads. All techniques achieved FDA quality standards, apart from posttransfusion recovery rate, which was only reached by the microbeads-based technique.
  
  
  CONCLUSIONS
  LR with CD45 microbeads not only reduces animal usage but also provides a more efficacious method regarding posttransfusion red blood cell recovery and, hence, provides a promising alternative to commonly used methods.
authors.affiliation: Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Frankfurt/Main, Germany.
authors.forename: Dania
authors.identifier: http://orcid.org/0000-0003-2086-0107
authors.initials: D
authors.lastname: Fischer
authors.affiliation: Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Frankfurt/Main, Germany.
authors.forename: Julian
authors.initials: J
authors.lastname: Büssow
authors.affiliation: Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Frankfurt/Main, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Meybohm
authors.affiliation: Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Frankfurt/Main, Germany.
authors.forename: Kai
authors.initials: K
authors.lastname: Zacharowski
authors.affiliation: Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Frankfurt/Main, Germany.
authors.forename: Carla
authors.initials: C
authors.lastname: Jennewein
mesh_terms: D000818:Animals; D017707:Erythrocyte Transfusion; D005434:Flow Cytometry; D007958:Leukocyte Count; D047589:Leukocyte Reduction Procedures / Q000295:instrumentation / Q000379:methods*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL