Alternative treatment paradigm for thalassemia using iron chelators.
OBJECTIVE
beta-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.


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 beta-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 beta-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.


CONCLUSIONS
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.
Szuber
Natasha
N
Department of Physiology, Medicine, and Experimental Medicine, McGill University, Montreal, Quebec, Canada.
Buss
Joan L
JL
Soe-Lin
Shan
S
Felfly
Hady
H
Trudel
Marie
M
Ponka
Prem
P
D000818:Animals; D004195:Disease Models, Animal; D004353:Drug Evaluation, Preclinical; D004910:Erythrocyte Membrane / Q000378:metabolism* / Q000473:pathology; D017707:Erythrocyte Transfusion; D006801:Humans; D007501:Iron / Q000378:metabolism*; D007502:Iron Chelating Agents / Q000494:pharmacology* / Q000627:therapeutic use; D008706:Methemoglobin / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects*; D012156:Reticulocytes / Q000378:metabolism / Q000473:pathology; D017086:beta-Thalassemia / Q000378:metabolism / Q000473:pathology / Q000628:therapy*
D007502:Iron Chelating Agents; D008706:Methemoglobin; D007501:Iron