Changes in membrane asymmetry upon cryopreservation of red blood cells with different cryoprotectants

Objectives: Red blood cell (RBC) stability during cryopreservation is depending on the modification of structure membrane by cryoprotectant agents (CPAs) and low temperature. Design and methods: The aim of this work was the investigation of asymmetrical distribution changes of phosphatidylserine (PS) during RBC cryopreservation with CPAs glycerol and polyethylene glycol (PEG-1500) by flow cytometry. Results: The PS exposure of RBCs has been investigated after incubation with CPAs before freezing. Glycerol didn't affect significantly the PS distribution up to 24 h of incubation. The number of annexin-V labelled cells reached 10% and 40% after 1 h and 24 h of PEG incubation, respectively. After freeze-thawing of RBC suspensions the number of cells which bind annexin-V was 15% and 32% in the presence of glycerol and PEG, respectively. Following RBC incubation into Ringerglucose medium, the difference of PS exposure in the membrane of cells cryopreserved in the presence of glycerol and PEG has been detected.