Clot contraction of whole blood diminishes during storage and can be restored by adding platelets

BACKGROUND: The contraction of blood clots is a dramatic platelet-dependent process that minimizes the impact of thrombosis and supports the closure of lacerations. Whole blood (WB) stored up to 35 days is increasingly used to treat hemorrhagic shock, but the clot contractibility of this stored blood is unknown. We hypothesized that clot contractibility decreases during storage but can be restored by adding platelets. STUDY DESIGN AND METHODS: WB units from 6 donors were stored at 4°C for 35 days. Apheresis platelet units from 11 donors were stored for 5 days at 22°C with gentle oscillation. Clot contraction of WB and WB supplemented with platelets was measured daily in vitro using optical tracking. Platelets were added at a concentration of 30,000/μL. RESULTS: Clot contraction of 6 WB samples diminished over 35 days of storage. The initial contraction rate and final contraction extent began declining at week 3. By week 5, the initial contraction rate was 67% slower, and the final contraction extent was 49% lower compared to week 1. Adding platelets at week 5 improved the initial contraction rate by 22% and the final contraction extent by 16%. CONCLUSION: WB stored at 4°C loses a portion of its clot contractility as early as 3 weeks of storage, which may affect patients receiving stored blood. The addition of room-temperature (RT) stored platelets can improve clot contraction, offering a potential strategy to enhance the effectiveness and safety of stored WB for hemorrhagic shock when fresh blood is unavailable.