Towards blood on demand: Rapid post-thaw isolation of red blood cells from multicomponent cryoprotectants.

Severe blood loss due to trauma, anaemia, or chemotherapy necessitates immediate red blood cell (RBC) transfusions. The short shelf-life of RBCs at 4 °C complicates emergency supply management. Glycerol is the state-of-the-art cryopreservative for RBCs but the time from thawing to transfusion is more than 1 hour, due to the slow, extensive washing process. This presents a major barrier to blood on demand in emergency or military situations. Here we demonstrate that polyampholytes combined with DMSO and trehalose can cryopreserve human RBCs and allow rapid washout in under 30 minutes. Post wash-out, preserved RBCs exhibit comparable viability, morphological integrity, and function to glycerol-preserved RBCs. This method enhances processing and handling, facilitating the use of frozen RBCs in healthcare, military, and other fields reliant on constant donation. Rapid-washout solutions could unlock blood-on-demand from cryopreserved stocks, improving cold-chain management and reducing reliance on walking donors.