Synergistic effects of liposomes, trehalose, and hydroxyethyl starch for cryopreservation of human erythrocytes.

Red blood cells (RBCs) can be cryopreserved using glycerol as a cryoprotective agent, but one of the main disadvantages is the time-consuming deglycerolization step. Novel cryopreservation strategies for RBCs using nontoxic cryoprotective agents are urgently needed. The effect of DMPC, DOPC, and DPPC liposomes on survival of RBCs cryopreserved with trehalose and HES has been evaluated. DMPC caused hemolysis before freezing and affected RBC deformability parameters. DMPC treated RBCs displayed a strong increase in trehalose uptake compared to control cells, whereas DOPC treated liposomes only displayed a slight increase in trehalose uptake. High intracellular trehalose contents were observed after cryopreservation. The recovery of cells incubated with trehalose and liposomes, frozen in HES ranged between 92.6 and 97.4% immediately after freezing. Recovery values of RBCs frozen in HES, however, decreased to 66.5% after 96 h at 4°C compared to 77.5% for DOPC treated RBCs. The recovery of RBCs incubated and frozen in trehalose medium was 77.8%. After 96 hours post-thaw storage recovery of these cells was 81.6%. DOPC and DPPC treated RBCs displayed higher recovery rates (up to 89.7%) after cryopreservation in trehalose compared to control RBCs. Highest survival rates were obtained using a combination of trehalose and HES: 97.8% directly after thawing and 81.8% 96-h post-thaw. DOPC liposomes, trehalose and HES protect RBCs during cryopreservation in a synergistic manner. The advantage is that the protective compounds do not need to be removed before transfusion.