Patients with beta-thalassaemia major frequently suffer from hypersiderosis which leads to hemochromatosis of major organs such as the heart and liver. Little information exists about the ultrastructural pathology of the human heart in beta-thalassaemia patients. Five Cypriot patients with elevated blood ferritin and intractable heart failure were investigated. Cardiac biopsies from these patients were studied by light and electron microscopy, as well as by X-ray microanalysis. Ultrastructural examination revealed the presence of disrupted myocytes showing loss of myofibers, dense nuclei, and a variable number of pleomorphic electron dense granules. These cytoplasmic granules or siderosomes consisted of iron-containing particles as confirmed by X-ray microanalysis. It is likely that the ultrastructural changes observed in myocytes of patients with beta-thalassaemia are largely due to iron deposition.
Cardiac damage caused by iron overload toxicity is the main cause of death in thalassemia patients. Biopsy samples of poorly chelated thalassemia patients who suffered congestive cardiac failure (CCF) show extensive iron deposition in the myocardium. In one patient who survived CCF, a cardiac biopsy was performed during the removal of a thrombus caused by a port-a-cath, which was used for the administration of intravenous (iv) deferoxamine (DFO). Ultrastructural pathology studies of the cardiac biopsy indicated extensive iron deposition in myocytes with accumulation of iron mainly in lysosomes, leading in some cases to their disruption. Damage to other intracellular components of the myocytes and loss of myofibers was also observed. The patient became intolerant to iv and subcutaneous (sc) DFO 2 years after the CCF, and was then treated with deferiprone (L1) for 7 years. Within 1 year of L1 treatment at 75-80 mg/kg/day, serum ferritin levels were reduced to <0.45 mg/L and she became asymptomatic, needing no further drugs for her cardiomyopathy. Lowering the L1 dose to 50-70 mg/kg/day caused an increase in serum ferritin levels. Maintenance of normal iron stores during the last 3 years as detected by cardiac and liver magnetic resonance imaging (MRI) T2 and T2* and normalization of serum ferritin levels (<0.15 mg/L) was observed following L1 therapy at 80-85 mg/kg/day. Deferiprone (>80 mg/kg/day) appears to be effective in the rapid clearance of cardiac iron, in the reversal of iron overload related cardiomyopathy, in the maintenance of normal iron stores and the overall long-term survival of thalassemia patients.
The importance of spleen, spleen iron and splenectomy has been investigated in 28 male and 19 female β-thalassemia major (β-ΤΜ), adult patients. In one study, an increase from about five (615 g; 19.5 × 11.0 × 6.0 cm) to twenty (2030 g; 25.0 × 17.5 × 12.0 cm) times higher than the normal size and weight of spleen has been observed in twenty patients following splenectomy. In a second study, the mean size for the liver (19.4 cm, range 13.5-26.0 cm) and spleen (15.6 cm, range 7.0-21.0 cm) measured by magnetic resonance imaging (MRI) and by ultrasound imaging for spleen (15.1 cm, range 9.0-21.0 cm) of 16 patients indicated that on average the spleen is about 80% of the size of the liver. In the third study, comparison of the iron load using MRI T(2)* and iron grading of stained biopsies indicated that substantial but variable amounts of excess iron are stored in the spleen (0-40%) in addition to that in the liver. Following splenectomy, total body iron storage capacity is reduced, whereas serum ferritin (p = 0.0085) and iron concentration in other organs appears to increase despite the reduction in the rate of transfusions (p = 0.0001) and maintenance of hemoglobin levels (p = 0.1748). Spleen iron seems to be cleared faster than liver iron using effective chelation protocols. Spleen iron is a major constituent of the total body iron load in β-ΤΜ patients and should be regularly monitored and targeted for chelation. Normalization of the body iron stores at an early age could maintain the spleen in near normal capacity and secondary effects such as cardiac and other complications could be avoided.
Tissue damage caused by oxidative stress is a common characteristic of many conditions involving different major organs such as the brain, heart, liver and kidneys. The treatment of such conditions using classical antioxidants is not in most cases sufficient or effective because it lacks specificity and has a low therapeutic index. Increased evidence from in vitro, in vivo and clinical studies suggest that deferiprone (L1) can be used as a potent pharmaceutical antioxidant by mobilizing labile iron and copper and/or inhibiting their catalytic activity in the formation of free radicals and oxidative stress in tissue damage. The high therapeutic index, tissue penetration, rapid iron binding and clearance of the iron complex, and the low toxicity of L1, support its application as an antioxidant pharmaceutical for adjuvant, alternative or main therapy, especially in conditions where other treatments have failed. Substantial clinical improvement and reversal in most cases of the tissue damage has been observed in cardiomyopathy in thalassemia, diabetic nephropathy and glomerulonephritis in kidney disease, Friedreich's Ataxia and Fanconi Anemia patients. In contrast to L1, both deferoxamine (DFO) and deferasirox (DFRA) have major disadvantages in their use in non iron loading conditions due to toxicity implications. Further studies in the above and other conditions and optimization of the L1 therapy in each individual will increase the prospects of the application and role of L1 as a universal antioxidant pharmaceutical.
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