Deferasirox reduces oxidative DNA damage in bone marrow cells from myelodysplastic patients and improves their differentiation capacity

Abstract

Patients with low-risk myelodysplastic syndromes (MDS) usually develop iron overload. This leads to a high level of oxidative stress in the bone marrow (BM) and increases haematopoietic cell dysfunction. Our objective was to analyse whether chelation with deferasirox (DFX) alleviates the consequences of oxidative stress and improves BM cell functionality. We analysed 13 iron-overloaded MDS patients' samples before and 4-10 months after treatment with DFX. Using multiparametric flow cytometry analysis, we measured intracellular reactive oxygen species (ROS), DNA oxidation and double strand breaks. Haematopoietic differentiation capacity was analysed by colony-forming unit (CFU) assays. Compared to healthy donors, MDS showed a higher level of intracellular ROS and DNA oxidative damage in BM cells. DNA oxidative damage decreased following DFX treatment. Furthermore, the clonogenic assays carried out before treatment suggest an impaired haematopoietic differentiation. DFX seems to improve this capacity, as illustrated by a decreased cluster/CFU ratio, which reached values similar to controls. We conclude that BM cells from MDS are subject to higher oxidative stress conditions and show an impaired haematopoietic differentiation. These adverse features seem to be partially rectified after DFX treatment.The myelodysplastic syndromes (MDS) comprise a heterogeneous group of malignant haematopoietic stem cell disorders that result in clonal haematopoiesis. This disorder occurs with cytopenia and dysplastic features as a consequence of ineffective haematopoiesis. Clinical presentation and evolution of MDS is heterogeneous. Anaemic syndrome, increased risk of infections and haemorrhagic manifestations are often present. These clinical aspects vary depending on the predominant cytopenia in each case, with anaemia being the most prevalent (up to 80-90% of patients) and the major

Protein Carbonylation in Patients with Myelodysplastic Syndrome: An Opportunity for Deferasirox Therapy

“…Proteomic analysis also revealed an increase in protein carbonylation in erythroid precursors, which could be related to the increased DNA damage in MDS CD34+ cells [4,41]. Indeed, a recent study demonstrated an increase in DNA damage in MDS patients, which was reverted by treatment with an iron chelator [6].…”

“…Previous assessments of oxidative stress in BM of patients with MDS using antioxidant biomarkers showed that all BM cell types have an imbalance in ROS levels that is related to lower overall survival [6,10,42]. This phenotype was also reverted by iron chelation [6,42], suggesting that amelioration of the oxidative stress effects by DFX treatment is beneficial for these patients. Indeed, an improvement in the pathogenesis of MDS has previously been reported after DFX therapy [20,33].…”

“…A current “hot” topic in MDS research is oxidative stress and its potential effects on cell biology, DNA damage and carcinogenesis [1,2]. Whereas the origin of MDS disease is now better understood, high levels of reactive oxygen species (ROS) and consequent oxidative damage in hematopoietic cells have been reported in patients with this disease [3,4,5,6], but the consequences are less clear. Regulation of intracellular ROS levels is known to be key for maintaining the balance between self-renewal, proliferation, and differentiation of progenitor cells and a loss of this control can lead to diseases characterized by BM failure [7,8].…”

Inhibition of Xanthine Oxidoreductase Enhances the Potential of Tyrosine Kinase Inhibitors against Chronic Myeloid Leukemia

“…Cell clonogenic capacity was analyzed by colony-forming unit (or CFU) assays in semisolid methylcellulose medium as previously described [30]. K562 and KCL22 cells or primary bone marrow mononuclear cells (BM-MNC) from CML patients were treated with two different TKIs (either imatinib or nilotinib), allopurinol, and their combinations in RPMI medium for 48 h. Cells were then washed with PBS and 500 K562 and KCL22 cells, or 12500 BM-MNC cells were resuspended in 500 µL of "HSC-CFU-basic" or "HSC-CFU-complete w/o Epo," respectively (Miltenyi Biotec; Madrid, Spain) and seeded on a culture plate.…”

Less iron improves MDS haematopoiesis

“…In the work published in this issue of the British Journal of Haematology, Jiménez‐Solas et al () explored this question in an elegant work on primary samples from MDS patients.…”