Long-term cold storage of platelets for transfusion based on zwitterionic magnetic microgels

Hypothermic preservation of platelets at 22 °C with an agitation process realizes their rapid transfusion to treat hemorrhage and thrombocytopenia in the clinic. However, platelets suffer from activation, aggregation, and bacterial contamination during storage, resulting in a limited shelf life of 5 days. Cold storage in a refrigerator can effectively prevent bacterial growth, but this condition is challenging to preserve platelets, owing to cold-induced reactive oxygen species (ROS) overproduction or platelet desialylation. Here, we design a zwitterionic magnetic microgel assembly to preserve platelets for a long time without agitation at 4 °C. The microgel assembly can scavenge cold-induced ROS and provide a super-hydrophilic 3D environment to isolate platelets, preventing platelet activation, aggregation, and desialylation. Moreover, the antifouling property of microgel assembly at 4 °C can ensure the anti-bacterial environment for platelets. As a result, the cold storage time of platelets significantly extended to 7 days. This work serves as a springboard for the development of platelet-based clinical applications.