Objective β-thalassemia major, or Cooley's anemia, is a red blood cell disorder requiring lifelong blood transfusions for survival. Erythrocytes accumulate toxic iron at their membranes, triggering ...an oxidative cascade that leads to their premature destruction in high numbers. We hypothesized that removing this proximate iron compartment as a primary treatment, using standard and alternative orally active iron chelators, could prevent hastened red cell removal and, clinically, perhaps alleviate the need for transfusion. Materials and Methods Iron chelators of the pyridoxal isonicotinoyl hydrazone family (pyridoxal isonicotinoyl hydrazone and its analog pyridoxal ortho -chlorobenzoyl hydrazone) were evaluated in addition to the present mainstay, desferrioxamine and deferiprone, in vitro and in vivo. Results Treatment of human β-thalassemic erythrocytes with chelators resulted in significant depletion of membrane-associated iron and reduction of oxidative stress, as evaluated by methemoglobin levels. When administered to β-thalassemic mice, iron chelators mobilized erythrocyte membrane iron, reduced cellular oxidation, and prolonged erythrocyte half-life. The treated thalassemic mice also showed improved hematological abnormalities. Remarkably, a beneficial effect as early as the erythroid precursor stage was manifested by normalized proportions of mature vs immature reticulocytes. All four compounds were also found to mitigate iron accumulation in target organs, a critical determinant for patient survival. In this respect, pyridoxal ortho -chlorobenzoyl hydrazone displayed higher activity relative to other chelators tested, further diminishing iron in liver and spleen by up to approximately fivefold and twofold, respectively. Conclusion Our study demonstrates the ability of iron chelators to improve several of the fundamental pathological disturbances of thalassemia, and reveals their potential for clinical use in diminishing requirement for transfusion when administered early in disease development.
Thalassemia is a blood disorder requiring lifelong transfusions for survival. Erythrocytes accumulate toxic iron at their membranes, triggering an oxidative cascade that leads to their premature ...destruction. We hypothesized that removing this proximate iron compartment as a primary treatment using novel iron chelators, could prevent cell death and alleviate the need for transfusion. Novel, highly cell permeable iron chelators, pyridoxal isonicotinoyl hydrazone and pyridoxal ortho-chlorobenzoyl hydrazone (o-108) were compared to the present mainstay, desferrioxamine and deferiprone, in vitro and in vivo. Treatment of human model b-thalassemic erythrocytes with chelators resulted in significant depletion of membrane-associated iron (P < 0.002) and reduced oxidative stress, as indicated by methemoglobin levels (P < 0.01). When administered to β-thalassemic mice, iron chelators mobilized erythrocyte membrane iron (P < 0.05), reduced cellular oxidation (P < 0.03), and prolonged erythrocyte survival. Consistently, these mice showed substantial correction of hematological abnormalities (P < 0.05). A beneficial effect as early as the erythroid precursor stage, was also determined by normalized proportions of mature versus immature reticulocytes (P < 0.05). Remarkably, all four compounds reduced iron accumulation in target organs (P < 0.05). Most importantly, o-108 revealed superior activity compared to desferrioxamine, further decreasing iron in spleen and liver by ~2-fold and ~5-fold, respectively (P < 0.05). Our study demonstrates that iron chelators ameliorate thalassemia in a human and murine model, and validates their primary use as an alternative to transfusion therapy.
Thalassemia is a blood disorder requiring lifelong transfusions for survival. Erythrocytes accumulate toxic iron at their membranes, triggering an oxidative cascade that leads to their premature ...destruction. We hypothesized that removing this proximate iron compartment as a primary treatment using novel iron chelators, could prevent hastened red cell removal and clinically alleviate the need for transfusion. Novel, highly cell permeable iron chelators, pyridoxal isonicotinoyl hydrazone (PIH) and pyridoxal ortho-chlorobenzoyl hydrazone (o-108) were compared to the present mainstay, desferrioxamine (DFO) and deferiprone (L1), in vitro and in vivo . Treatment of human model β-thalassemic erythrocytes with chelators resulted in significant depletion of membrane-associated iron and reduced oxidative stress as indicated by a decrease in methemoglobin levels. When administered to β-thalassemic mice, iron chelators mobilized erythrocyte membrane iron, reduced cellular oxidation, and prolonged erythrocyte survival. Consistently, these mice showed improved hematological abnormalities. A beneficial effect as early as the erythroid precursor stage was also determined by normalized proportions of mature versus immature reticulocytes. Remarkably, all four chelators reduced iron accumulation in target organs. Most importantly, o-108 revealed superior activity, decreasing iron in liver and spleen by ∼5-fold and ∼2-fold, respectively, compared to DFO. Our study demonstrates that iron chelators ameliorate thalassemia in a human and murine model, and validates their primary use as an alternative to transfusion therapy.
Thalassemia is a blood disorder requiring lifelong transfusions for survival. Erythrocytes accumulate toxic iron at their membranes, triggering an oxidative cascade that leads to their premature ...destruction. We hypothesized that removing this proximate iron compartment as a primary treatment using novel iron chelators, could prevent hastened red cell removal and clinically alleviate the need for transfusion. Novel, highly cell permeable iron chelators, pyridoxal isonicotinoyl hydrazone (PIH) and pyridoxal ortho-chlorobenzoyl hydrazone (o-108) were compared to the present mainstay, desferrioxamine (DFO) and deferiprone (L1), in vitro and in vivo . Treatment of human model beta-thalassemic erythrocytes with chelators resulted in significant depletion of membrane-associated iron and reduced oxidative stress as indicated by a decrease in methemoglobin levels. When administered to beta-thalassemic mice, iron chelators mobilized erythrocyte membrane iron, reduced cellular oxidation, and prolonged erythrocyte survival. Consistently, these mice showed improved hematological abnormalities. A beneficial effect as early as the erythroid precursor stage was also determined by normalized proportions of mature versus immature reticulocytes. Remarkably, all four chelators reduced iron accumulation in target organs. Most importantly, o-108 revealed superior activity, decreasing iron in liver and spleen by ~5-fold and ~2-fold, respectively, compared to DFO. Our study demonstrates that iron chelators ameliorate thalassemia in a human and murine model, and validates their primary use as an alternative to transfusion therapy.
