抄録
To examine the cryoprotective role of glycerol in preserving frozen red blood cells, we used a differential scanning calorimeter to study the thermal behavior of three kinds of glycerol-base cryoprotectants: a) the glycerol-water (binary) system, b) the glycerol-phosphate buffered saline (complex system), and c) the clinically used glycerol-based cryoprotective solutions. The results were as follows; (i) thermal characteristics for the binary system were the same as those previously reported, (ii) both the complex system and clinical-use cryoprotectants had the same characteristics as the binary system, (iii) a red cell suspension in the complex system showed the same tendency in hemolysis after freezing and thawing as that in the clinical-use cryoprotectants. (iv) the critical final glycerol concentration where hemolysis drops abruptly was 14% and 29% for rapid and slow freezing methods, respectively, (v) the final glycerol concentration where hemolysis becomes small was lower than that at which the glass transition occurs. This indicates that we must consider the microscopic cell behavior during freezing.
