Deformability of red blood cells (RBCs) is an essential feature that enables RBCs to access and transit the capillary bed, thereby ensuring oxygen supply to the muscle. The influence of long-time blood storage on RBC deformability has already been investigated, but without a consensus regarding the results. Therefore, the aim of the present study was to elucidate changes in RBC deformability during long-term storage with different storage conditions tested.

Blood of ten male subjects was anticoagulated and cooled to 4°C prior to separation of RBCs from other blood constituents. RBCs were split into (I) packed RBCs and (II) RBCs adjusted to a physiological hematocrit using a stabilizing solution. All samples were stored at 4°C. RBCs deformability of stored and fresh blood (FB) samples was examined at twelve time points during an eight-week storage period. A blood count was prepared on each examination day.

The results reveal that RBC deformability of FB was stable during the entire study period. RBC deformability of (I) and (II) were stable until days 17 and 21, respectively. Deformability then dropped by 39.58 ± 1.76% (I;P< 0.001) and 18.33 ± 2.38% (II;P< 0.001), respectively.

In conclusion, the storage condition mainly influences RBC deformability. A gradual increase in MCV during storage may in part be responsible for the observed deformability reduction because the cell volume becomes a limiting factor for the ability of RBCs to deform. Future studies must now reveal other factors affecting RBC deformability during storage, and how RBC deformability can be preserved.