Diethylenetriaminopentaacetic acid is unsuitable for long-term preservation of RBCs

BACKGROUND: The addition of an appropriate metal chelator, such as diethyle netriaminopentaacetic acid (DTPA) to stored blood has been shown to be effe ctive in a short-term (0-12 days) prevention of lipid peroxidation of store d RBCs. However, its long-term effectiveness has not been carefully evaluat ed. STUDY DESIGN AND METHODS: Blood was preserved in simulated blood bank condi tions 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 custom-built laser viscodiffractometer. Malondialdeh yde (MDA), an index of lipid peroxidation, and the extent of vesiculation o f the stored blood were quantified concurrently. RESULTS: It was found that MDA values for DTPA-supplemented blood at the en d of a 28-day storage period were significantly elevated compared with the DTPA-free counterpart (23.50 +/- 3.2 vs. 16.10 +/- 2.5 muM; p <0.05). In ad dition, DTPA-supplemented blood was more susceptible to vesiculation than i ts DTPA-free counterpart (31.26 +/- 4.1 vs. 10.26 +/- 1.5% of acetyl cholin esterase release, p <0.001). These data are also in accordance with the fin ding of the deformability profile result, indicating that DTPA-supplemented blood exhibits not only a decrease in deformability index, but also a tend ency to shift the profile to a lower osmolality compared with that of contr ols (a dehydration phenomenon). CONCLUSION: Long-term (0-28 days) preservation of human RBCs with DTPA caus ed a gradual increase in MDA production, a progressive enhancement of the s everity of vesiculation, and an alteration in the deformability profile. Fr ee-radical-mediated oxidative damage is likely to be the culprit for this o bserved phenomenon. In addition, the direct effect of DTPA on RBC structura l integrity must be considered.