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Oxidative stress resulting from hemolysis and formation of catalytically active hemoglobin: protective strategies
O Ziouzenkova1, L Asatryan, A Sevanian
1Department of Molecular Pharmacology and Toxicology, School of Pharmacy, University of Southern California, Los Angeles, USA.
Objectives:
The possible oxidative complications induced by free hemoglobin (Hb) released during the blood storage are discussed together with therapeutic strategies using vitamin E and specific inhibitor haptoglobin. Prooxidative properties of Hb in blood have been examined using LDL as a marker for oxidative stress, which contribute to toxicity observed in a number of pathologies aggravated by hemolysis or hemorrhagic lesions as well as after the transfusion of stored blood.
Materials:
Experiments were performed using fresh blood or stored blood that was obtained from a blood bank on the day corresponding to the identified expiration date.
Methods:
Oxidation of LDL was determined by means of the formation of mildly oxidized LDL (LDL-) using anion exchange chromatography. Concentrations of Hb were determined spectrophotometrically.
Results:
Hb-mediated oxidative processes in cellular membranes have been well documented over the past decade. We showed that catalytic activity of Hb released during blood storage was sufficient to increase the proportion of LDL- fraction in blood after 4 h incubation at 37 degrees C. The intensity of this oxidative process as well as the release of Hb varied in different donors and may depend on the antioxidant capacity of blood. Accumulation of Hb during storage was significantly decreased in range of 15 - 32% in blood supplemented with low concentrations of alpha-, gamma-tocopherols. Similar effects were observed in the presence of low concentrations of haptoglobin, which has been reported as a specific inhibitor of hemoglobin-mediated oxidation.
Conclusions:
The specific inhibition of hemoglobin-mediated oxidation in lipoproteins and cellular membranes may improve the quality of stored blood and help to decrease complications arising from oxidative stress after transfusions or during hemolytic events. Based on growing evidence for a role of oxidatively modified LDL in atherosclerosis, hemolytic pathologies should receive further consideration as risk factors for cardiovascular disease.