In vivo tracking of transfused platelets for recovery and survival studies: An appraisal of labeling methods

The measurement of recovery and survival of platelets is an important decisive factor when ‘new’ platelet products have been developed. Recovery and survival measurements are mostly performed with radioactive-labeled platelets in healthy volunteers. This approach is required by the FDA for acceptance of platelet products that differ substantially in production or storage conditions from standard methods. However, due to regulatory obstacles, such radiolabeling studies are only carried out in designated institutes. Many countries do not require radioactive labeling studies in volunteers prior to accepting new products, and rather rely on surrogate tests. Also, the European guide to the preparation of blood components does not require this step. This paper reviews alternative, non-radioactive methods, which includes biotinylation of platelets, and discrimination of transfused platelets based on HLA discrepancy. The benefits and disadvantages of these methods will be discussed.