ABSTRACT
Blood cells can be regarded as a classical field of application of low-temperature biology. Cryopreservation methods have been developed for all different categories of blood cells (including blood stem cells) and blood corpuscles. For granulocytes, however, no clinically applicable method has been found until today. However, frozen red blood cells (also known as RBC or erythrocytes), platelets (also known as thrombocytes), lymphocytes, monocytes, and hematopoietic progenitor cells (from peripheral blood as well as from bone marrow) are currently being used for various diagnostic and clinical purposes. When Polge et al. (1949) discovered rather accidentally that glycerol was able to protect spermatozoa from damage during freezing and thawing, a rapid
development of deep-freezing preservation of biological cells set in. This has led to a variety of cell-specific cryopreservation protocols. The methods differ with regard to cell concentrations, protective solutions used (cryoprotectants and their concentrations), temperature-time-histories during cooling and rewarming, and storage temperature. In addition, some of the cryoprotectants are not well tolerated in the concentrations required (e.g., dimethyl sulfoxide [Me2SO] for platelets) or lead to an osmotically induced lysis of the cryoprotectant-loaded cells when transfused into an isotonic organism (e.g., glycerol for red blood cells). In these cases, a washing procedure is required after thawing before the application.
