The oxidative status of cells is determined by the balance between pro-oxidants and antioxidants. Pro-oxidants, referred to as reactive oxygen species (ROS), are classified into radicals and nonradicals. The radicals are highly reactive due to their tendency to accept or donate an electron and attain stability. When cells experience oxidative stress, ROS, which are generated in excess, may oxidize proteins, lipids and DNA - leading to cell death and organ damage. Oxidative stress is believed to aggravate the symptoms of many diseases, including hemolytic anemias. Oxidative stress was found in the beta-hemoglobinopathies (sickle cell anemia and thalassemia), glucose-6-phosphate dehydrogenase deficiency, hereditary spherocytosis, congenital dyserythropoietic anaemias and Paroxysmal Nocturnal Hemoglobinuria. Although oxidative stress is not the primary etiology of these diseases, oxidative damage to their erythroid cells plays a crucial role in hemolysis due to ineffective erythropoiesis in the bone marrow and short survival of red blood cells (RBC) in the circulation. Moreover, platelets and polymorphonuclear (PMN) white cells are also exposed to oxidative stress. As a result some patients develop thromboembolic phenomena and recurrent bacterial infections in addition to the chronic anemia. In this review we describe the role of oxidative stress and the potential therapeutic potential of anti-oxidants in various hemolytic anemias.

We report in this paper that the DNAbinding drug mithramycin is a potent inducer of ␥-globin mRNA accumulation and fetal hemoglobin (HbF) production in erythroid cells from healthy human subjects and ␤-thalassemia patients. Erythroid precursors derived from peripheral blood were grown in 2-phase liquid culture. In this procedure, early erythroid progenitors proliferate and differentiate during phase 1 (in the absence of erythropoietin) into late progenitors. In phase 2, in the presence of erythropoietin, the latter cells continue their proliferation and mature into Hb-containing orthochromatic normoblasts. Compounds were added on days 4 to 5 of phase 2 (when cells started to synthesize Hb), and cells were harvested on day 12. Accumulation of mRNAs for ␥-globin, ␤-globin, ␣-globin, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and ␤-actin were measured by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR); induction of HbF was analyzed by high-performance liquid chromatography (HPLC) and, at cellular level, by flow cytometry. We demonstrated that mithramycin was able to up-regulate preferentially ␥-globin mRNA production and to increase HbF accumulation, the percentage of HbF-containing cells, and their IntroductionPharmacologically mediated regulation of the expression of the human ␥-globin genes could be of interest as a potential therapeutic approach for hematologic disorders, including ␤-thalassemia and sickle cell anemia. [1][2][3][4][5][6][7][8] It is well established, indeed, that increase of fetal hemoglobin (HbF) to 30% of the total hemoglobin (Hb) leads to a significant improvement of the clinical status of patients affected by these hematologic disorders. 1-3 Therefore, current research has been focused on screening of various agents, such as hormones, cytotoxic drugs, hemopoietic cytokines, and short fatty acids as agents capable of augmenting HbF levels in humans. [8][9][10][11][12][13] In this respect, DNA-binding drugs appear to be of great interest. 14,15 These agents are known to modify the formation of DNA/nuclear protein complexes and thereby control gene expression. [16][17][18][19][20][21][22] Our research group has recently demonstrated that tallimustine 16 and some cisplatin analogs, 15 as well as the guanosinecytosine (GC)-rich binders chromomycin and mithramycin (MTH), 14 are powerful inducers of erythroid differentiation of the human leukemic K562 cell line, suggesting that the pattern of erythroid differentiation and of ␥-globin gene expression could be influenced by treatment with DNA-binding drugs. Interestingly, while chromomycin binding to DNA generates stable complexes, MTH-DNA complexes are highly unstable. 23 This could explain the low toxicity of MTH as compared with chromomycin. 24 For this reason, MTH was proposed as a therapeutic agent in several neoplastic diseases (such as chronic myelogenous leukemia and testicular cancer), 25 in Paget disease, 26 and in pathologies associated with hypercalcemia. 27,28 The main issue of the present paper w...

In this review we summarize the achievements of medicinal chemistry in the field of pharmacological approaches to the therapy of beta-thalassemia using molecules able to stimulate the production of fetal hemoglobin (HbF). We first describe the molecular basis of the pathology and the biochemical rational of using HbF inducers for therapy; we then outlined the in vitro and in vivo experimental systems suitable for screening of such potential drugs, and finally we describe the different classes of compounds with emphasis on their advantages and disadvantages in the treatment. The results of these reviewed studies indicate that: (a) HbF inducers can be grouped in several classes based on their chemical structure and mechanism of action; (b) clinical trials with some of these inducers demonstrate that they are effective in ameliorating the symptoms of beta-thalassemia; (c) a good correlation was found between HbF stimulation in vivo and in vitro indicating that in vitro testing might be predictive of the in vivo response; (d) combined use of different inducers might maximize the effect, both in vitro and in vivo. However, (e) the response to HbF inducers, evaluated in vitro and in vivo, is variable, and some patients might be refractory to HbF induction by certain inducers; in addition, (f) several considerations call for caution, including the fact that most of the inducers exhibit in vitro cytotoxicity, predicting side effects in vivo following prolonged treatments.

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Background/aims Erythropoiesis in long‐term hemodialyzed (LTH) patients is supported by erythropoietin (rHuEpo) and intravenous (IV) iron. This treatment may end up in iron overload (IO) in major organs. We studied such patients for the parameters of IO in the serum and in major organs. Methods Patients were treated with rHuEpo (6–8 x 103 units × 1–3/wk) and IV 100 mg ferric saccharate. Results Of 115 patients, 21 had serum ferritin (SF) > 1000 ng/mL. This group was further analyzed. Their SF and transferrin saturation (TSAT) were 2688 ± 1489 ng/mL and 54.2 ± 32.7%, respectively (vs. 125–360 ng/mL and 20–50% in normal controls). Serum hepcidin was 60.1 ± 29.5 nm (vs. 10.61 ± 6.44 nm in controls) (P < 0.001). Nineteen patients had increased malonyldialdehyde, a product of lipid peroxidation, indicating oxidative stress. T2* MRI disclosed in 19 of 21 patients moderate to severe IO in the liver and spleen, in three of eight patients in the pancreas, but in no patient in the heart. After stopping IV iron for a mean of 12 months, while continuing rHuEpo, the mean SF decreased in 11 patients to 1682 ng/mL and the mean TSAT decreased to 28%, whereas hemoglobin did not change indicating that tissue iron was utilized. Conclusion High SF correlates with IO in the liver and spleen, but not in the heart.