A useful relationship between the presence of extramedullary erythropoeisis and the level of the soluble form of the transferrin receptor in a large cohort of adult patients with thalassemia intermedia: a prospective study

Anemia and iron overload as prognostic markers of outcomes in β-thalassemia

INTRODUCTION

Ineffective erythropoiesis and subsequent anemia as well as primary and secondary (transfusional) iron overload are key drivers for morbidity and mortality outcomes in patients with β-thalassemia.

AREAS COVERED

In this review, we highlight evidence from observational studies evaluating the association between measures of anemia and iron overload versus outcomes in both non-transfusion-dependent and transfusion-dependent forms of β-thalassemia.

EXPERT OPINION

Several prognostic thresholds have been identified with implications for patient management. These have also formed the basis for the design of novel therapy clinical trials by informing eligibility and target endpoints. Still, several data gaps persist in view of the challenge of assessing prospective long-term outcomes in a chronic disease. Pooling insights on the prognostic value of different measures of disease mechanism will be key to design future scoring systems that can help optimize patient management.

Impact of genotype on multi-organ iron and complications in patients with non-transfusion-dependent β-thalassemia intermedia

We evaluated the impact of the genotype on clinical and hematochemical features, hepatic and cardiac iron levels, and endocrine, hepatic, and cardiovascular complications in non-transfusion-dependent (NTD) β-thalassemia intermedia (TI) patients. Sixty patients (39.09 ± 11.11 years, 29 females) consecutively enrolled in the Myocardial Iron Overload in Thalassemia project underwent Magnetic Resonance Imaging to quantify iron overload, biventricular function parameters, and atrial areas and to detect replacement myocardial fibrosis. Three groups of patients were identified: homozygous β+ (N = 18), heterozygous β0β+ (N = 22), and homozygous β0 (N = 20). The groups were homogeneous for sex, age, splenectomy, hematochemical parameters, chelation therapy, and iron levels. The homozygous β° genotype was associated with significantly higher biventricular end-diastolic and end-systolic volume indexes and bi-atrial area indexes. No difference was detected in biventricular ejection fractions or myocardial fibrosis. Extramedullary hematopoiesis and leg ulcers were significantly more frequent in the homozygous β° group compared to the homozygous β+ group. No association was detected between genotype and liver cirrhosis, hypogonadism, hypothyroidism, osteoporosis, heart failure, arrhythmias, and pulmonary hypertension. Heart remodelling related to a high cardiac output state cardiomyopathy, extramedullary hematopoiesis, and leg ulcers were more pronounced in patients with the homozygous β° genotype compared to the other genotypes analyzed. The knowledge of the genotype can assist in the clinical management of NTD β-TI patients.

Long-term safety and erythroid response with luspatercept treatment in patients with β-thalassemia

Background

β-thalassemia is a hereditary blood disorder resulting in ineffective erythropoiesis and anemia. Management of anemia with regular blood transfusions is associated with complications including iron overload. Here, we report long-term safety and efficacy results of the first clinical study of luspatercept in β-thalassemia, initiated in 2013, enrolling adults with both nontransfusion-dependent (NTD) and transfusion-dependent (TD) β-thalassemia.

Objectives

The objective was to report long-term safety data, for up to 5 years of treatment, for 64 patients with TD or NTD β-thalassemia, and long-term efficacy data for a subset of 63 patients with β-thalassemia who received high-dose luspatercept (0.6-1.25 mg/kg): 31 NTD and 32 TD patients.

Design

The study was a phase 2, noncontrolled, open-label trial comprising a dose-finding base phase and a 5-year extension phase.

Methods

Endpoints include safety; erythroid response over a continuous 12-week period [NTD: hemoglobin increase from baseline ⩾1.0 or ⩾1.5 g/dl; TD: red blood cell (RBC) transfusion burden reduction, ⩾20%, ⩾33%, or ⩾50%]; and changes in biomarkers of ineffective erythropoiesis, iron metabolism parameters, Functional Assessment of Chronic Illness Therapy - Fatigue (FACIT-F) scores, and 6-min walking distance.

Results

Median duration of luspatercept exposure for NTD and TD patients was 910 days (range, 40-1850) and 433 days (range, 21-1790), respectively. Seventeen of 31 (54.8%) NTD patients achieved a mean hemoglobin increase of ⩾1.5 g/dl and 19 of 32 (59.4%) TD patients achieved ⩾50% reduction in RBC transfusion burden, during any continuous 12-week period. Median cumulative duration of response was 1126 days (range, 127-1790) for NTD patients and 909 days (range, 87-1734) for TD patients. The most common treatment-related adverse events of any grade were bone pain, headache, and myalgia.

Conclusion

Long-term assessment of patients with β-thalassemia showed luspatercept was associated with sustained increases in hemoglobin levels in NTD patients and sustained transfusion burden reductions in TD patients.

Trial registration

(ClinicalTrials.gov Identifiers: NCT01749540 and NCT02268409).

Plain Language Summary

Long-term safety and erythroid response with luspatercept treatment in patients with β-thalassemia Background: β-thalassemia is a genetic blood disorder caused by mutations in the β-globin gene, which encodes one of the proteins that comprise hemoglobin, a key constituent of red blood cells. Patients with β-thalassemia experience anemia, the main treatment for which is blood transfusions. Long-term repeated blood transfusions lower patients' quality of life, use hospital resources, and the resulting accumulation of excess iron can cause organ failure and decrease life expectancy. The severity of the anemia experienced by patients with β-thalassemia varies; patients with transfusion-dependent β-thalassemia require regular blood transfusions, compared with those with nontransfusion-dependent β-thalassemia who require infrequent transfusions, or even none at all, to manage their symptoms. Luspatercept (Reblozyl^®) is an agent that stimulates the production of red blood cells and is used to treat anemia caused by β-thalassemia. However, the long-term effects of luspatercept treatment on patients with β-thalassemia are not known.Objective: In this study, we report the long-term safety of luspatercept in 64 adult patients with either transfusion-dependent or nontransfusion-dependent β-thalassemia, and the long-term efficacy of high-dose luspatercept (0.6-1.25 mg/kg) in a subset of 63 patients.Results: The average time period that patients were treated with luspatercept was 910 days for nontransfusion-dependent β-thalassemia and 433 days for transfusion-dependent β-thalassemia. We report that in patients with nontransfusion-dependent β-thalassemia, luspatercept treatment was associated with sustained increases, just over 3 years, in hemoglobin levels. Likewise, in transfusion-dependent β-thalassemia, luspatercept treatment was associated with a sustained reduction, 2.5 years, in the amount of blood transfusion required to manage their anemia. Long-term treatment with luspatercept was not associated with any new side effects compared with previous short-term treatment studies. The most common side effects were headache (27 patients), bone pain (20 patients), and muscle pain (14 patients) with more than 90% of these patients experiencing these side effects as mild severity.Conclusion: The results of this study show that in patients with either transfusion-dependent or nontransfusion-dependent β-thalassemia, luspatercept provides lasting reduction in anemia with mostly mild and predictable side effects.

The use of hydroxyurea in the real life of MIOT network: an observational study

BACKGROUND

Hydroxyurea (HU) has been widely used in clinical practice to manage patients with non-transfusion dependent thalassemia (NTDT). Few data are available about the effects of its administration in Italian patients. We assessed hematological and non-hematological outcomes following short- and long-term exposure to HU.

RESEARCH DESIGN AND METHODS

We considered 71 NTDT patients (30 females) enrolled in the Myocardial Iron Overload in Thalassemia Network and treated for >12 months with HU.

RESULTS

The mean duration of HU treatment was 8.23±5.79 years, starting at a mean age of 37.02±12.06 years. A significant increase in hemoglobin and mean corpuscular volume values and a down-regulation of all erythropoietic and/or hemolysis indices were detected after at least 12 months of treatment. In 28 patients the hemoglobin increase was ≥1.0 g/dl, associated with a higher HU dose. The hematological response dropped in long-term treatment. A favorable impact of HU treatment in limiting the progression of several complications typical of NTDT syndrome was observed.

CONCLUSION

Our findings seemed to suggest that in several NTDT patients HU could be still a valid option to limit the advance in overall disease clinical burden without carrying significant adverse events and increase in mortality.

Thalassemia and hepatocellular carcinoma: links and risks

The increased survival and lifespan of thalassemia patients, in the setting of better iron overload monitoring and chelation, have also however increased the incidence of diseases and complications, which were less likely to develop. Among these, one of the most worrying in recent years is hepatocellular carcinoma (HCC). Due to blood transfusions, many patients with thalassemia are or have been infected with hepatitis C virus (HCV) or hepatitis B virus (HBV), especially those born before the 1990s or in countries in which universal HBV vaccination and safe blood programs are still not completely implemented. However, HCC has also been described in nontransfused patients and in those who are HCV- and HBV-negative. Therefore, other risk factors are involved in hepatocarcinogenesis in thalassemia. The following review analyzes recent literature on the role of different risk factors in the progression of liver disease in thalassemia as well as the importance of surveillance. Treatment of HCC in thalassemia is still highly debated and requires further studies.

Prevalence of extramedullary hematopoiesis, renal cysts, splenic and hepatic lesions, and vertebral hemangiomas among thalassemic patients: a retrospective study from the Myocardial Iron Overload in Thalassemia (MIOT) network

We determined the prevalence of incidental extracardiac findings (IEF) at Magnetic Resonance Imaging (MRI) potentially related to anemia and hypoxia in age- and sex-matched populations (N = 318) with thalassemia major (TM) and thalassemia intermedia (TI) enrolled in the Myocardial Iron Overload in Thalassemia network. Overall, IEFs were detected in 33.3% and 25.8% of patients with TI and TM, respectively (P = 0.114). TI and TM patients had elevated but comparable prevalence of renal, splenic and liver cysts, and vertebral hemangiomas while TI patients had a significant higher frequency of extramedullary hematopoiesis (EMH) (15.1% vs 4.4%; P = 0.002). The prevalence of total IEFs increased with advancing age. TI non-transfusion-dependent patients had a significantly lower frequency of renal cysts than TI transfusion-dependent patients (8.8% vs 26.4%; P = 0.005). The prevalence of renal cysts in the thalassemic population was significantly higher than that in the general population (19.2% vs 1.9%; P < 0.0001). Our data on renal cysts indicate a significant higher prevalence of these IEFs compared to the general population, suggesting the role of the inappropriate activation of the hypoxia-inducible factor system linked to the chronic hypoxia. The significant prevalence of IEF in thalassemia patients undergoing MRI for iron quantification should prompt the discussion of the inclusion of IEF in the MRI report.

Erythropoiesis and Iron Homeostasis in Non-Transfusion-Dependent Thalassemia Patients with Extramedullary Hematopoiesis

Background

Extramedullary hematopoiesis (EMH) is common in non-transfusion-dependent thalassemia (NTDT) patients. Clinical presentations of EMH vary as MRI screening is not feasible. Hence, serum biomarkers are used to predict the risk of EMH.

Materials and Methods

52 NTDT patients, including 26 EMH (+) and 26 EMH (-), together with 26 healthy controls, were enrolled in this case-control study from 2013 to 2016. EMH was confirmed by computed tomography or MRI. Demographic, transfusion, genetic, laboratory, and liver iron concentration (LIC) data, as well as clinical complications, were analyzed.

Results

EMH (+) patients had significantly higher serum ferritin (SF), growth differentiation factor 15 (GDF15), and erythropoietin (EPO) levels compared with EMH (-) patients and controls. The levels of erythroferrone (ERFE), hepcidin, and sTfR did not differ significantly between EMH (+) and EMH (-) patients (p>0.05). In NTDT patients, serum ERFE was not related to SF, LIC, hepcidin, sTfR, EPO, GDF15, and Hb levels. GDF15, EPO concentrations, and GDF15 to sTfR and GDF15 to EPO ratios are able to determine the presence of EMH with considerable sensitivity and specificity.

Conclusions

GDF15, EPO, and GDF15 to EPO and GDF15 to sTfR ratios are potential biomarkers for the early prediction of NTDT in patients who are at risk for EMH.

Imbalance of erythropoiesis and iron metabolism in patients with thalassemia

Aim: This study aimed to evaluate the imbalance of erythropoiesis and iron metabolism in patients with thalassemia. Methods: 192 patients with non-transfusion-dependent thalassemia (NTDT), 94 patients with transfusion-dependent thalassemia (TDT) and 101 healthy controls were recruited between June 2013 and December 2016 in the Hematology Department, the First Affiliated Hospital of Guangxi Medical University. The groups were compared in terms of levels of erythropoiesis biomarkers [growth differentiation factor 15 (GDF15), erythropoietin (EPO) and soluble transferrin receptor (sTfR)] and of iron overload biomarkers [serum ferritin (SF), liver iron concentration (LIC) and cardiac T2*] and hepcidin. Results: The levels of GDF15, EPO, sTfR, LIC and SF were significantly higher in patients with thalassemia. The levels of GDF15 and EPO were significantly higher in patients with TDT compared to NTDT. Those with iron overload had higher EPO, GDF15, SF and sTfR levels compared with non-iron overload patients. Hepcidin levels and ratios of hepcidin to erythropoietic activity and to iron biomarker levels were lower in patients with β-thalassemia intermedia or hemoglobin (Hb) E/β-thalassemia than in patients with HbH disease. The hepcidin levels were correlated negatively with the levels of EPO, GDF15 and sTfR in patients with NTDT and TDT, but correlated positively with SF and Hb levels only in patients with TDT. Conclusions: Patients with thalassemia showed iron overload, reduced hepcidin levels, and a greater extent of ineffective erythropoiesis. The hepcidin levels were more strongly related to ineffective erythropoiesis compared with iron overload. The imbalance between erythropoiesis and iron metabolism differed across different thalassemia types.

Interaction of Transfusion and Iron Chelation in Thalassemias

The relationship between blood transfusion intensity, chelatable iron pools, and extrahepatic iron distribution is described in thalassemia. Risk factors for cardiosiderosis are discussed with particular reference to the balance of transfusional iron loading rate and transferrin-iron utilization rate as marked by plasma levels of soluble transferrin receptors. Low transfusion regimens increase residual erythropoiesis allowing for apotransferrin-dependent clearance of non-transferrin-bound iron species otherwise destined for myocardium. The impact of transfusion rates on chelation dosing required for iron balance is also shown.

Soluble form of transferrin receptor-1 level is associated with the age at first diagnosis and the risk of therapeutic intervention and iron overloading in patients with non-transfusion-dependent thalassemia

We retrospectively evaluated the relationship between serum transferrin receptor-1 (sTfR1) and some fundamental events in the life and the management (the age at diagnosis, the age at the first red blood cells transfusion, the age at splenectomy, and the overall need of chelation therapy) of 111 patients with non-transfusion-dependent thalassemia (NTDT) subdivided in four genetic entities: patients with homozygous or compound heterozygous state for β-thalassemia, patients with triplicated α genotype associated with β heterozygosity, patients with deletional HbH, and patients with the combination of a β defect plus a β chain variant. We found that the group with homozygous or compound heterozygous state for β-thalassemia had the highest sTfR1 levels and that the presence of increased sTfR1 levels (>5 times normal) was associated with a complex and severe history of disease requiring splenectomy, occasional red blood cells transfusions, and early start and continuous iron chelation therapy.The complexity in the management of NTDT patients is an emerging issue due to the wide heterogeneity of clinical behavior. Our data indicate that the measurement of sTfR1 levels, a common laboratory test, could contribute to correctly stratify disease history and the iron chelation strategy in NTDT patients.

Presence of the IVS-I-6-Mutated Allele in Beta-Thalassemia Major Patients Correlates with Extramedullary Hematopoiesis Incidence

Extramedullary hematopoiesis (EMH) results from the extension of hematopoietic tissue beyond the confines of the bones. Since the initiation of regular transfusion programs from an early age for all thalassemia major (ΤΜ) patients, EMH has not been considered a clinical issue anymore. The present study aims to record the prevalence of EMH in chronically transfused ΤΜ patients followed at our institution and to investigate possible risk factors associated with its occurrence. The project was designed as a retrospective, nonexperimental, descriptive, exploratory study. In total, the study enrolled 104 patients. EMH was revealed in 15/104 (14%) patients. The presence of intravening sequence (IVS)-I-6 was significantly related with the development of EMH (p < 0.05). No other demographic or biological factor studied was found to be related with the presence of EMH. The study stresses a profound incidence of asymptomatic EMH in a solid group of well-transfused ΤΜ patients. Given the high incidence of the IVS-I-6 allele in the Mediterranean and Middle Eastern region, high-quality, prospective, multicenter studies could confirm the association of EMH occurrence with the presence of the IVS-I-6 mutation and further evaluate the exact role of this mutation in the EMH process.

Molecular and clinical analysis of haemoglobin Lepore in Campania, a region of Southern Italy

OBJECTIVE

To date in Italy, there is paucity on data about the prevalence, clinical and haematological features of patients carrying the haemoglobin (Hb) Lepore variant in homozygous or in association with other haemoglobinopathies.

METHODS

Here we report the results of a retrospective analysis on 33 patients from Campania, a region of Southern Italy, historically followed at 'UOSD Malattie Rare del Globulo Rosso' of Cardarelli hospital, Naples, Italy.

RESULTS

We described 33 patients carrying the Hb Lepore variant: 21 compound heterozygotes with a common thalassaemia allele, six patients with homozygous state for Hb Lepore, five patients with Hb Lepore/Hb S and one patient with Hb Lepore/Hb Neapolis were identified. All individuals carried haplotype I or V.

DISCUSSION

These thalassaemic patients showed different phenotypes ranging from severe disease with early blood transfusion dependency to moderate form of thalassaemia intermedia. In most cases, thalassaemia mutation type determined the severity of the disease.

CONCLUSION

A great variability of clinical phenotype among the same genotypes was also observed suggesting the presence of unknown genetic modifiers acting in combination with Hb Lepore.

Iron overload across the spectrum of non-transfusion-dependent thalassaemias: role of erythropoiesis, splenectomy and transfusions

Non-transfusion-dependent thalassaemias (NTDT) encompass a spectrum of anaemias rarely requiring blood transfusions. Increased iron absorption, driven by hepcidin suppression secondary to erythron expansion, initially causes intrahepatic iron overload. We examined iron metabolism biomarkers in 166 NTDT patients with β thalassaemia intermedia (n = 95), haemoglobin (Hb) E/β thalassaemia (n = 49) and Hb H syndromes (n = 22). Liver iron concentration (LIC), serum ferritin (SF), transferrin saturation (TfSat) and non-transferrin-bound iron (NTBI) were elevated and correlated across diagnostic subgroups. NTBI correlated with soluble transferrin receptor (sTfR), labile plasma iron (LPI) and nucleated red blood cells (NRBCs), with elevations generally confined to previously transfused patients. Splenectomised patients had higher NTBI, TfSat, NRBCs and SF relative to LIC, than non-splenectomised patients. LPI elevations were confined to patients with saturated transferrin. Erythron expansion biomarkers (sTfR, growth differentiation factor-15, NRBCs) correlated with each other and with iron overload biomarkers, particularly in Hb H patients. Plasma hepcidin was similar across subgroups, increased with >20 prior transfusions, and correlated inversely with TfSat, NTBI, LPI and NRBCs. Hepcidin/SF ratios were low, consistent with hepcidin suppression relative to iron overload. Increased NTBI and, by implication, risk of extra-hepatic iron distribution are more likely in previously transfused, splenectomised and iron-overloaded NTDT patients with TfSat >70%.

Cortical bone invasion in non-transfusion-dependent thalassemia: tumefactive extramedullary hematopoiesis reviewed

OBJECTIVE OF THE STUDY

To assess the prevalence of cortical bone invasion (CBI) with secondary extramedullary hematopoiesis (EMH) in patients with non-transfusion-dependent thalassemia (NTDT), to determine its predilection sites on thoracic and abdominal imaging, to determine whether there is an association between various clinical and hematological parameters, and to evaluate its various findings mainly on magnetic resonance imaging (MRI), in addition to computed tomography (CT) scans.

MATERIALS AND METHODS

This is a retrospective cohort study of 57 patients with NTDT imaged by CT or MRI. Both clinical and laboratory data were gathered. An imaging scoring system was used to describe the appearance of CBI by MRI.

RESULTS

Twenty-seven patients (47.4 %) were found to have CBI and EMH with the most common location being the thoracic spine. Splenectomy and lower hemoglobin level were found to be independent risk factors for its development. Most lesions were homogenous (70 %), had predominant red marrow signal (67 %), and well-defined margins (89 %).

CONCLUSION

CBI and secondary tumefactive EMH are common findings in patients with NTDT, with distinct imaging and clinical characteristics. An increased risk was seen in patients with splenectomy and lower hemoglobin. The imaging scoring system described is helpful in diagnosing and describing this entity, hence precluding unnecessary biopsies.

Extramedullary hematopoiesis is associated with lower cardiac iron loading in chronically transfused thalassemia patients

The aim of this study was to evaluate, in a large cohort of chronically transfused patients, whether the presence of extramedullary hematopoiesis (EMH) accounts for the typical patterns of cardiac iron distribution and/or cardiac function parameters. We retrospectively selected 1,266 thalassemia major patients who had undergone regular transfusions (611 men and 655 women; mean age: 31.3 ± 8.9 years, range: 4.2-66.6 years) and were consecutively enrolled within the Myocardial Iron Overload in Thalassemia network. The presence of EMH was evaluated based on steady-state free precession sequences; cardiac and liver iron overloads were quantified using a multiecho T2* approach; cardiac function parameters and pulmonary diameter were quantified using the steady-state free precession sequences; and myocardial fibrosis was evaluated using the late gadolinium enhancement technique. EMH was detected in 167 (13.2%) patients. The EMH+ patients had significantly lower cardiac iron overload than that of the EMH- patients (P = 0.003). The patterns of cardiac iron distribution were significantly different in the EMH+ and EMH- patients (P < 0.0001), with a higher prevalence of patients with no myocardial iron overload and heterogeneous myocardial iron overload and no significant global heart iron in the EMH+ group EMH+ patients had a significantly higher left ventricle mass index (P = 0.001) and a significantly higher pulmonary artery diameter (P = 0.002). In conclusion, in regularly transfused thalassemia patients, EMH was common and was associated with a thalassemia intermedia-like pattern of cardiac iron deposition despite regular transfusion therapy.

Study of serum haptoglobin level and its relation to erythropoietic activity in Beta thalassemia children

BACKGROUND

Serum haptoglobin (Hp) is a reliable marker for hemolysis regardless the inflammatory state.

OBJECTIVE

We investigated the possible relation between Hp depletion and hemolysis severity, hepatitis C virus (HCV) infection and iron load in β-thalassemia children.

METHODS

Twenty two β-thalassemia major (TM),20 β-thalassemia intermedia (TI) children with 20 age and sex matched healthy controls were involved. Pre-transfusion hemoglobin level was considered. Serum ferritin, Hp and transferrin receptor levels (sTfR) (by ELISA ), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) (by colorimetric method) were assayed. Markers of hepatitis C virus (HCV) were done by PCR.

RESULTS

The mean Hp levels among the studied groups were as follows; 8.02 ± 0.93 (mg/dl), 8.6 ±0.72 (mg/dl) and 122 ± 18.5(mg/dl) for TM, TI and the controls respectively. Both patient groups had significantly lower Hp level compared to the controls (P<0.0001) with significant lower level in TM compared to TI children ( P= 0.034). Significant inverse correlations were found between serum Hp and sTfR levels ( reflecting the erythropoietic activity) in thalassemia children combined and in each group (TM and TI) as well as among HCV infected children. STfR was the only significant independent predictor for serum Hp level (t= -5.585, P<0.0001). Among HCV infected patients, no significant correlation was found between serum Hp and serum transaminases.

CONCLUSION

Serum Hp depletion in thalassemia had significant relation to disease severity and correlated well with their erythropoietic activity, as assessed by the measurement of sTfR without significant relation to HCV infection. Extensive multicenter studies are recommended.

Increasing prevalence of thalassemia in America: Implications for primary care

Thalassemia, once a rarity in the United States, is increasingly encountered in clinical practice due to shifts in immigration. Early carrier screening in at-risk populations can help clinicians implement genetic counseling and prevent new cases. Chronic transfusions are the mainstay of therapy for patients with severe thalassemia (beta thalassemia major), and are used intermittently in individuals with milder forms of thalassemia (Hb H/H Constant Spring disease and beta thalassemia intermedia). Iron overload is a major source of morbidity and mortality in individuals with transfusion and non-transfusion-dependent thalassemia, necessitating iron chelation therapy. Iron overload contributes to increased risk of cirrhosis, heart failure, and endocrinopathies, while ineffective erythropoiesis and hemolysis contribute to multiple complications, including splenomegaly, extramedullary hematopoiesis, pulmonary hypertension, and thrombosis. An understanding of the importance of carrier screening, complications, monitoring, and management strategies, coupled with collaboration with a hematologist with thalassemia expertise, is essential to reduce the morbidity and mortality in patients with thalassemia.

The importance of spleen, spleen iron, and splenectomy for determining total body iron load, ferrikinetics, and iron toxicity in thalassemia major 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.

Quantitative analysis of murine terminal erythroid differentiation in vivo: novel method to study normal and disordered erythropoiesis

Terminal erythroid differentiation is the process during which proerythroblasts differentiate to produce enucleated reticulocytes. Although it is well established that during murine erythropoiesis in vivo, 1 proerythroblast undergoes 3 mitosis to generate sequentially 2 basophilic, 4 polychromatic, and 8 orthochromatic erythroblasts, currently there is no method to quantitatively monitor this highly regulated process. Here we outline a method that distinguishes each distinct stage of erythroid differentiation in cells from mouse bone marrow and spleen based on expression levels of TER119, CD44, and cell size. Quantitative analysis revealed that the ratio of proerythroblasts:basophilic:polychromatic:orthromatic erythroblasts follows the expected 1:2:4:8 ratio, reflecting the physiologic progression of terminal erythroid differentiation in normal mice. Moreover, in 2 stress erythropoiesis mouse models, phlebotomy-induced acute anemia and chronic hemolytic anemia because of 4.1R deficiency, the ratio of these erythroblast populations remains the same as that of wild-type bone marrow. In contrast, in anemic β-thalassemia intermedia mice, there is altered progression which is restored to normal by transferrin treatment which was previously shown to ameliorate the anemic phenotype. The means to quantitate in vivo murine erythropoiesis using our approach will probably have broad application in the study of altered erythropoiesis in various red cell disorders.