A Comparative Study of the Effects of Glycerol and Hydroxyethyl Starch in Canine Red Blood Cell Cryopreservation

Abstract

ABSTRACT. Hydroxyethyl starch (HES) is a nonpenetrating extracellular cryoprotectant. In contrast to glycerol, it does not require laborintensive removal from thawed red blood cells (RBCs) prior to transfusion. In this study, we compared glycerol and HES, and assessed HES as a substitute for glycerol in cryopreserved canine RBCs. The RBCs were preserved for 2 months in liquid nitrogen using a 20% (w/v) glycerol solution, and variable concentrations of HES solution. We evaluated the two cryoprotectants by the percentage of postthaw hemolysis from the total free hemoglobin, saline stability, osmotic fragility, and by observing the erythrocyte morphology using a scanning electron microscope after thawing. The optimal concentration of HES was 12.5% (w/v) for the cryopreservation of canine RBCs. The thaw hemolysis, saline stability, and osmotic fragility index were 25.6 ± 4.7%, 87.8 ± 6.9%, and 0.445 ± 0.024% NaCl respectively. These parameters resemble the results of RBCs frozen in a 20% (w/v) glycerol solution, which are 24.7 ± 5.2%, 99.2 ± 0.1%, and 0.485 ± 0.023% NaCl respectively. From a morphological point of view, 12.5% (w/v) HES showed the best cryoprotection of RBCs compared to the other concentrations of HES. These results suggest that HES could be a possible substitute for glycerol for the cryopreservation of canine RBCs.

Frozen Red Blood Cells in Transfusion

“…Non penetrating cryoprotecting agents protect cells by a process called 'vitrification', where they form glassy shell around the cell. HES is one of the promising cryoprotecting agent for cryopreservation of RBC, since its removal from thawed RBC prior to transfusion is not required [4][5][6].…”

“…For cryopreservation of RBC, glycerol is used in either 20% or 40% weight/volume (W/V) concentration; the methods are termed as low glycerol concentration (LGC) or high glycerol concentration (HGC) respectively [4,5]. HGC have advantages of initial slow uncontrolled freezing rate and storage of RBC below -65°C as against initial rapid controlled cooling and storage temperature below -120°C in LGC [4].…”

“…Cryoprotecting agents are classified as penetrating and non-penetrating. Glycerol is a penetrating group of cryoprotecting agent [4,5]. The high concentration of glycerol in RBC prevents formation of The salient features of the NBRL method are described below:…”

The effects of freezing on long-term storage of canine erythrocytes

“…With the advances in veterinary transfusion medicine, researchers have discovered the contraindications of the usage of Whole Blood and thus verged to use the blood components, instead, for the treatment of miscellaneous diseases in order to minimize the risks (Kim et al 2004). The next step was to improve blood storage techniques in an attempt to compensate growing demands for blood transfusion, and therefore, new studies were designed investigating long-term cryopreservation of RBCs (Kim et al 2004, Kim et al 2007, Pallota et al 2012.…”

“…The next step was to improve blood storage techniques in an attempt to compensate growing demands for blood transfusion, and therefore, new studies were designed investigating long-term cryopreservation of RBCs (Kim et al 2004, Kim et al 2007, Pallota et al 2012. The aim was to prolong the shelf life of blood products (Pallota et al 2012) and prevent economic losses.…”