Diethylenetriaminopentaacetic acid is unsuitable for long-term preservation of RBCs

BACKGROUND: The addition of an appropriate metal chelator, such as diethylenetriamnopentaacetic acid (DTPA) to stored blood has been shown to be effective in a short-term (0-12 days) prevention of lipid peroxidation of stored RBCs. However, its long-term effectiveness has not been carefully evaluated. STUDY DESIGN AND METHODS: Blood was preserved in simulated blood bank conditions with or without the addition of DTPA for 4 weeks. Aliquots of stored blood were taken weekly from the storage bag and the deformability profile was determined using a custombuilt laser viscodiffractometer. Malondialdehyde (MDA), an index of lipid peroxidation, and the extent of veslculation of the stored blood were quantified concurrently. RESULTS: It was found that MDA values for DTPA-supplemented blood at the end of a 28-day storage period were significantly elevated compared with the DTPA-free counterpart (23.50 ± 3.2 vs. 16.10 ± 2.5 μM; p<0.05). In addition, DTPA-supplemented blood was more susceptible to vesiculation than its DTPA-free counterpart (31.26 ± 4.1 vs. 10.26 ± 1.5% of acetyl cholinesterase release, p<0.001). These data are also in accordance with the finding of the deformability profile result, indicating that DTPA-supplemented blood exhibits not only a decrease in deformability index, but also a tendency to shift the profile to a lower osmolality compared with that of controls (a dehydration phenomenon). CONCLUSION: Long-term (0-28 days) preservation of human RBCs with DTPA caused a gradual increase in MDA production, a progressive enhancement of the severity of vesiculation, and an alteration in the deformability profile. Free-radical-mediated oxidative damage is likely to be the culprit for this observed phenomenon. In addition, the direct effect of DTPA on RBC structural integrity must be considered.