Novel method to leukoreduce murine blood for transfusion: how to reduce animal usage

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). STUDY DESIGN AND 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. CONCLUSION 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.