The widely used erythrocyte preservation methods involve obtainment of erythrocytes from donors (e.g., using the apheresis method, or by separation from donated whole blood) in the form of packed red blood cells (erythrocyte concentrate) with reduced content of white blood cells and subsequent storage of obtained erythrocyte concentrate in plastic bags at a temperature within the range from 1° C. to 6° C. for a period of 42 days. For instance, this method is currently implemented through the use of apheresis apparatuses produced by Haemonetics Corp (Baintree, Mass., USA) and Terumo BCT, Inc. (Lakewood, Colo., USA) and assemblies of bags for blood components (also supplied together with apheresis apparatuses) manufactured of polyvinylchloride with plasticizer his (2-ethylhexyl) phthalate (DEHP, CAS No. 117-81-7). Only about 20 percent of RBC collected using this method, the majority is separated from donated whole blood). For platelets it is opposite.
The red blood cells (RBC) for transfusion are collected from donors into CPD or CP2D anticoagulant preservative solution. The RBC are separated by centrifugation method, and a solution for long term storage is added (e.g., AS-3). White blood cells are removed by filtration, and the RBC/AS-3 is stored in DEHP plasticized PVC bags at 1-6° C. for up to 42 days prior to transfusion. It is well know that the DEHP plasticizer has an important protective effect on the RBC, reducing the amount of hemolysis over the course of storage. It is desirable to minimize this storage hemolysis and other storage damage to provide the maximum therapeutic benefit to the transfusion recipient as well as minimize the potential adverse sequelae associated with RBC transfusion. The DEHP plasticizer (used for manufacturing such bags) dissolves partially in the erythrocyte concentrate in the course of storage of the RBCs, thereby diffusing from bag material and exerting additional preserving action upon the erythrocytes. It was shown (Dumont Larry J. et al. Exploratory in vitro study of red blood cell storage containers formulated with an alternative plasticizer. Transfusion, 2012 July 52(7):1439-1445) that the presence of DEHP plasticizer reduces the number of erythrocytes that lysed during the storage of the erythrocyte concentrate.
DEHP plasticizer in the erythrocyte concentrate decomposes into toxic components, one of which—namely, is mono-ethylhexyl phthalate (MEHP). Thus, a disadvantage of preserving erythrocytes in bags manufactured of material containing DEHP plasticizer is the danger of intoxication of patients after transfusion of a erythrocyte concentrate unit. The indicated negative consequence may increase quite significantly in the case of multiple transfusions. Taking this circumstance into account, it is preferable to store erythrocyte concentrate in bags made of materials that do not contain DEHP plasticizer. Because of theoretical adverse effects in certain high risk patient populations, it is desirable to find an alternative to DEHP as a component in RBC storage bags. However, in this case, the preserving effect (caused by the presence of DEHP plasticizer) is missing, and hence, the number of erythrocytes that lyse during storage increases.
A method for platelet preservation described in US 2010/0009334, published on Jan. 14, 2010, is known. This method involves obtaining a platelet concentrate from blood obtained from an individual, keeping the platelet plasma in a gas medium containing from 65% to 100% of xenon under pressure from 3.5 to 5 atm, subsequent cooling down of platelet concentrate to a temperature within the range from approximately 1° C. to 6° C., and storage under the conditions of the above-indicated temperature and pressure of gas medium. Platelets were obtained by apheresis. This method results in an increase in the storage period for platelets.
However, as practical experience shows, the application of this method for preserving other blood cells (e.g., erythrocytes) is characterized by a number of disadvantages. First, this method presumes the use of a gas mixture, which includes oxygen or atmospheric air in addition to xenon. However, the presence of oxygen during storage of erythrocytes stimulates erythrocytolysis (hemolysis). Hemolysis of erythrocytes during storage leads to unsatisfactory quality of final product—namely, low number of intact cells in the erythrocyte concentrate, which impairs the efficiency of the latter after transfusion to patients. Even more important are adverse effects of transfusion because of the high hemolysis in the transfused RBC. In the US, if more than 1% of the erythrocyte concentrate experiences hemolysis, the erythrocyte concentrate is considered unacceptable for blood transfusion. In other countries, the amount of hemolysis must be as low as 0.8% for the erythrocyte concentrate for the erythrocyte concentrate to acceptable for blood transfusion.
In view of the current state of the art, there is a need to develop a method for the preservation of erythrocyte concentrate that ensures storage of the latter for a period of no less than 42 days without considerable degradation of erythrocytes quality and that enables the use of plastic bags manufactured without using DEHP plasticizer.