Assessment of Whole Blood Cold Stored Platelets (Brrr)

Subjects will be enrolled for evaluation of platelet recovery and survival. Healthy subjects will be consented and enrolled into the study until 8 subjects have completed the recovery and survival evaluations at 4, 8, 12, 16, and 20 days storage. The order in which storage intervals are evaluated will be randomized. Eight subjects will then be evaluated at the mid-range interval between longest storage period that meets acceptances criteria and shortest storage period that does not meet acceptance criteria. For instance, if at 12 days of storage the 95% lower confidence limits for recoveries are NOT ≥50% of fresh and survivals are LESS than one day, but at 8 days of storage recoveries are ≥50% of fresh and survivals are at least than one day, we will then evaluate 10 days of storage. If the 10 day storage does not meet acceptance criteria we will evaluate 9 days. If the 10 day storage does meet acceptance criteria we will evaluate 11 days. Eight subjects will be evaluated at each storage interval.

Subjects will donate one unit of whole blood. This unit will be maintained as whole blood in CPD (Citrate Phosphate Dextrose anticoagulant) not leukoreduced and not separated into components. These WB units will be stored under refrigerated conditions (4°C) for between 4 and 20 days after collection. Prior to refrigeration samples from the unit will be obtained for various in vitro tests.

In vivo Measurements:

At the end of each subject's storage period a ~200 mL aliquot of whole blood will be withdrawn from the unit. This aliquot will be centrifuged and the platelets extracted. The platelets will be radiolabeled with 51-Cr or 111-In. On that day, the subject will return to the Blood Center and provide a 43 mL fresh blood sample. Platelets from that sample will be harvested and labeled with the other isotope. Radiolabeling will be done by the BEST method. These aliquots will be sequentially infused into the subject. The estimated amount of the isotope is ≤15 μCi of indium and ≤20 μCi of chromium will be infused. The total radiation dose is approximately 40 μCi for a total body absorbed dose of 0.0273 rad (0.273 mSv) and a splenic absorbed dose of 3.2 rad (32 mSv). Venous samples (10 mls/draw) will be taken within 2 hours after reinfusion and on days 1, 2, 3, 5, 7 ± 1, and 10 ± 2. After these visits, the subject's participation will end and they will exit the study. Stored and fresh platelet recoveries and survivals will be determined and comparisons will be made between each subject's fresh and stored platelet recoveries.

In vitro Assays:

The following assays will be performed using a 50 ml sample obtained from the whole blood pre and post storage:

• platelet count
• platelet function assays (mean platelet volume, morphology score, hypotonic shock response, extent of shape change, pH, PO2, PC02, HC03, glucose and lactate. Platelet aggregation response to standard agonists (ADP, collagen, arachidonic acid) will also be measured.
• platelet activation and apoptotic markers (p-selectin antigen, annexin V, platelet microparticles)
• thrombelastograph
• thrombin generation test
• plasma analysis of coagulation, complement, microparticles and fibrinolytic potential (thrombin-antithrombin complex (TAT), plasmin-antiplasmin complex (PAP), soluble cd 40l, plasminogen activator inhibitor (PAI-1 ), complement (C3a, C4d, C5b-9)
• sterility - bacterial cultures will be submitted after collection and the results evaluated 14 days later, or sooner if blood is stored for a shorter time period. A gram stain will be performed on the isolated 4° C platelets before reinfusion at the end of storage. All sterility tests must be negative before test platelets will be reinfused.