Application of phosphoenolpyruvate into the preparation of frozen and thawed red cells

Current standards recommend that red cells (RBCs) should be frozen within 5 days of donation. However, the guideline regarding freezing of RBCs may be cause difficulties in cases that autologous or rare units intended for transfusion may not be used as scheduled. Therefore, we examined how to freeze the RBCs after prolonged liquid storage. Standard units were stored at 4 degrees C for 21 days, incubated with rejuvenant solution containing 50 mM phosphoenolpyruvate (PEP), and then frozen at -80 degrees C for 4 weeks. RBCs recovery after deglycerolization procedure was 80 +/- 4% of the original value, which was similar to the level seen in fresh RBCs and twice that in nontreated units. The incubation of old RBCs with PEP not only increased ATP and 2,3-DPG levels, but also facilitated the transformation of crenated erythrocytes to discocytes. These results indicated that RBCs after maximum liquid storage could be frozen by rejuvenation with PEP solution, which would be expected to give adequate recovery of viable RBCs after processing for FTRC.