The Cryopreservation and Thawing of Red Blood Cells Using 25% Hydroxyethyl

Han, Tae Hee; Paik, In Ki

Abstract

BACKGROUND
The method using hydroxyethyl starch (HES) as a cryoprotectant is a simple, quick, and inexpensive way to make frozen red blood cells (RBCs) for an extended period. It needs neither sophisticated equipment nor skilled labor. As HES is a plasma expander, it does not have to be washed out before transfusion. But, it is not yet introduced in Korea to make frozen RBCs with HES. The aim of our study was to establish a method to cryopreserve RBCs using HES in Korea. METHODS: We rejuvenated RBCs (20 units) on the first day after expiration. They were washed three times with saline adenine glucose mannitol phosphate buffer solution (SAGMP), then their hemat-ocrits were adjusted up to 80%. The same weight of 25% HES was added to each RBC, to make a final mixture of 12.5% (wt/wt) HES-40% RBC. The blood bags were placed in a thin metal frame and frozen in liquid nitrogen. After 3 months, the blood bags were thawed in a 37 degrees Cwater bath. To evaluate the qualities of frozen-thawed RBCs, samples of HES-RBC mixtures before freezing and after thawing were tested for ATP, 2, 3-DPG, potassium, plasma hemoglobin, hemolysis %, and 30-minute saline stability (30-min SS). RESULTS: After thawing, the percentage (mean+/-SD) of RBC hemolysis was 1.6+/-0.4% (range, 1.1-2.6) and three units were over 2%; 30-min SS was 92.0+/-0.16% (88.4-93.8). Supernatant potassium and free hemoglobin were 15.6+/-3.5 mmol/L (10.9-23.0) and 215+/-62 mg/dL (139-318), respectively. The ATP and 2, 3-DPG of RBCs were 4.23+/-0.81 (3.31-6.51) micromol/g Hb and 8.46+/-1.62 (5.21-11.00) micromol/g Hb, respectively. CONCLUSIONS: Of the 20 units of RBCs tested, 17 units (85%) were within the criteria for transfusion (hemolysis<2%, 30 min SS>88%, potassium<75 mmol/L) after thawing. We could successfully freeze and thaw RBCs utilizing 25% HES as a cryoprotectant.