 An aliquot of the platelet concentrate separated from each unit of stored Mirasol-treated whole blood will be radiolabeled with either 111Indium Oxine or 51Chromium, and autologously infused. An intra-subject control will be utilized as per the BEST guidelines for platelet radiolabeling procedures. On the day of infusion, the subject will donate a fresh sample of whole blood. Platelets will be separated from this fresh sample and labeled with the radio-isotope that was not used to label the subjects Mirasol-treated platelet sample. The two radiolabeled platelet aliquots Mirasol-treated and fresh control will be infused simultaneously, and the recovery and survival of the two types of platelets will be measured according to standard institutional practice. 