Erythrocyte Storage Duration Affects Membrane Deformability

Blood banks consider six weeks to be the standard shelf life of blood for use in transfusion, but this timescale may need to be shortened.

Erythrocyte cell membranes undergo morphologic changes during storage, but it is unclear whether these changes are reversible, as after three weeks red cells in stored blood lose their ability to deliver oxygen where it is most needed.

Doctors involved in critical care medicine at Johns Hopkins University School of Medicine (Baltimore MD, USA) examined the blood given to 16 patients undergoing spinal fusion surgery. They assessed erythrocyte cell membrane deformability in patients before and after transfusion to determine the effects of storage duration and whether changes in deformability are reversible after transfusion.

Deformability was measured in samples drawn directly from the blood storage bags before transfusion and in samples drawn from patients before and after three postoperative days post-transfusion. In samples taken from the blood storage bags, they compared deformability of erythrocytes stored for a long duration, equal to or more than 21 days, those stored for a shorter duration, less than 21 days, and cell-salvaged erythrocytes. Deformability was assessed quantitatively using the elongation index (EI) measured by microfluidic slit-flow ektacytometer (Rheo Meditech; Seoul, South Korea), a method that determines the ability for the cell to elongate when exposed to shear stress.

The scientist found that found that after three weeks, red blood cells were not flexible enough to squeeze down through the fine capillaries, as they were more likely to have stiffer cell membranes. They also found that even after transfusion into patients, erythrocytes in blood that has stood on the shelf for more than three weeks fail to regain the flexibility they once had. This was the case even when the blood was in the patient, where the donated red cells would be in the best environment to repair their injury: the correct acidity, oxygen, and electrolyte levels.

The team found that patients who received fewer units of blood had healthier red cells overall, regardless of how old the blood was that they received. This probably means that if the patient does not receive too many damaged cells their loss of flexibility is less of a problem than if the patient receives many of them. Steven M. Frank, MD, the lead author of the study, said, "There's more and more information telling us that the shelf life of blood may not be six weeks, which is what the blood banks consider standard. If I were having surgery tomorrow, I'd want the freshest blood they could find. Once red cells lose their flexibility; red cells probably stay that way for the rest of their lives, which is about 120 days in total." The study was published on February 28, 2013, in the journal Anesthesia & Analgesia.

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Johns Hopkins University School of Medicine
Rheo Meditech