Engineered supercooling systems for enhanced long-term preservation of large-volume red blood cells in commercial blood bags

Reducing cell metabolism by lowering the storage temperature is an important method to improve the quality of stored RBCs and prolong the stored shelf life of RBCs. Traditional cryopreservation suffers from limitations such as tedious cytotoxic cryoprotectants (CPA) loading, unloading and ice-induced damage. Storage around 2-6 °C is an alternative method but only works for a short period due to significant storage lesions at this high storage temperature. We developed an improved supercooling preservation system for large-volume (100 ml) RBC suspensions in commercial polyvinylchloride (PVC) blood bags by minimizing favorable sites of ice nucleation and maintaining precise thermal control at -8 °C. This engineered protocol significantly reduces hemolysis, metabolic degradation, and oxidative stress while preserving RBC membrane integrity and functionality for up to 63 days. In vivo transfusion studies in New Zealand white rabbits demonstrate that supercooling-preserved RBCs achieve higher post-transfusion recovery rates, outperforming conventional storage methods. Our scalable and cost-effective supercooling system address critical needs for improving the quality of stored RBCs by achieving ice-free preservation, which representing a significant breakthrough in transfusion medicine.