Cold-stored platelets: revisiting assumptions and addressing variability to support implementation

Platelets are transfused to patients to prevent and stop bleeding. Conventionally, platelets are stored at room temperature (RT; 20-24 °C), however, this limits their shelf life to 5-7 days, due to an increased risk of bacterial proliferation at RT. In recent years, cold storage (2-6 °C) of platelets has regained interest, largely due to the potential to extend the shelf life up to 21 days. The historical use of cold-stored platelets and decades of foundational research has made their (re)implementation possible, with cold-stored platelets already being transfused in several countries, including the United States and Norway. However, as efforts continue to expand implementation, it is becoming increasingly evident that variations in processing methods from collection to transfusion, including the collection platform, storage solution and additional component modifications, may alter platelet characteristics during cold storage. This variability is largely overlooked and there is a need to recognize how these differences may affect clinical outcomes post-transfusion. This review outlines the assumptions that have been made regarding cold-stored platelets and discusses areas that require further consideration in an effort to inform future research and best practice.