[Erythrocytes after cryopreservation with HES: molecular, structural and functional characteristics]

The use of hydroxyethylstarch (HES) as an alternative to glycerol for cryopreservation of erythrocytes is presented. Immediately after thawing erythrocytes showed alterations in the membrane skeleton and a lowered rigidity of their membrane. However, a few minutes after resuspension in a physiological salt solution the initial poicilocytosis changed back to normocytotic forms. Intravital microscopy of the dog's mesentery revealed a homogeneous distribution of labeled previously cryopreserved erythrocytes in the capillary bed. The lowering of the ATP-level in the erythrocyte by about 20 to 40% was seen to be harmless, because the ATP-turn over rate was unchanged and the glucose support by the GluT 1 carrier was seen to be guaranteed. There was no decrease in the 2,3-DPG level on one hand, but a shift to the right in the O2-association as well as dissociation functions; the saturation capacity of hemoglobin with O2 on the other hand was constant. Free radical oxygen species, generated as a consequence of the freezing/thawing process, were inactivated by the erythrocyte's own antioxidation system. The 24-hour post-transfusion survival in dog amounted to about 95% and the in vivo-life time was normal. The hemolysis of human erythrocytes after thawing was about 5%. Most methodological and scientific problems concerning erythrocyte cryopreservation are considered to be solved. After official permission for use in humans, major benefits to many fields in surgery are expected: no more short-cuts in blood supply, practically complete exclusion of infectious risks, even unlimited use of autologous blood.