Intracellular sugars improve survival of human red blood cells cryopreserved at -80 degrees C in the presence of polyvinyl pyrrolidone and human serum albumin.

Cryopreservation with impermeable protectants has great significance on storage of human red blood cells. It has become feasible to use glycerol free cryopreservation for human red blood cells. This study focuses on the effect of intracellular trehalose or glucose on human red blood cells cryopreserved in the presence of polymer. Red blood cells were cryopreserved for 48 h-72 h at -80 degrees C. The data showed that the loading efficiency of glucose was significantly higher than that of trehalose, but trehalose loading process induced more hemolysis than glucose loading process. Compared with the other groups, the combination of intracellular glucose, PVP, and human serum albumin can significantly decrease the percent hemolysis after cryopreservation (P<0.01). However, the percent hemolysis induced by intracellular trehalose was less than that induced by extracellular trehalose, but the difference was not significant (P<0.05). The adenosine 5'-triphosphate (ATP) level and 2,3-diphosphoglycerate (2,3-DPG) level of cryopreserved red blood cells were significantly less than those of fresh red blood cells. However, sugars can provide certain protection for ATP and 2, 3-DPG compared with red blood cells cryopreserved in the absence of sugars. The protection of glucose on the metabolic function was more than that of trehalose. Cryopreservation can increase the percentage of cells with exposed phosphatidylserine (PS), but the ability of trehalose to maintain PS normal distribution is higher than that of glucose. Furthermore, intracellular sugars can protect membrane integrity of cryopreserved red blood cells, although a small portion of cells appeared spherocytic or echinocytic shape. Finally, most membrane proteins of cryopreserved red blood cells were similar to the membrane proteins of fresh red blood cells, but trehalose can result in loss of glyceraldehyde phosphate dehydrogenase (GAPD) and peroxiredoxin 2. In conclusion, it is feasible to cryopreserve red blood cells using polymer, human albumin and sugars as main protectants. The cryoprotective effect of glucose may be better than that of trehalose in the presence of PVP and human serum albumin, because sugar loading process causes more cell injuries in case of trehalose compared to glucose, and these injuries in turn manifest themselves during subsequent cryopreservation and thawing. In the future, finding an approach to decrease the injuries during trehalose loading process still is critical.