Assessment of Whole Blood Cold Stored Platelets

"Subjects will donate one unit of whole blood. This unit will be stored at 4°C for a predefined storage period. A variety of in vitro metabolic and functional platelet assays will be performed on the stored unit.~After the storage period, an aliquot from the whole blood unit will be processed to obtain platelets. The subject will return and donate a fresh sample of whole blood (43 mls) from which a fresh aliquot of platelets will be obtained. The stored and fresh platelets will each be labeled with a different radioisotope (either Chromium-51 or Indium-111) and reinfused into the subject. Using two different radioisotopes enables separate tracking of both the stored and fresh platelets. Follow-up blood samples will be drawn at 2 hours and on days 1, 2, 3, 5, 7±1 and 10±2. Stored and Fresh platelet recoveries and survivals will be calculated."