Dietary Supplementation with Ipriflavone Decreases Liver Iron Loading in Wild Type Mice

Abstract Hepcidin, a peptide hormone produced in the liver, decreases intestinal iron absorption and macrophage iron release by causing internalization and degradation of the iron exporter ferroportin. Because its levels are inappropriately low in patients with iron overload syndromes, Hepcidin is a potential drug target. We previously conducted a chemical screen in human hepatocytes (HepG2 cells) to identify small molecules that upregulate Hepcidin transcript levels. One of the small molecules that we identified was ipriflavone, a synthetic isoflavone, which has been used to treat osteoporosis in postmenopausal women. To evaluate ipriflavone’s effect on iron homeostasis in a mammalian model, we placed groups of 5-week old C57BL/6 male mice on a soy-free, iron-sufficient diet, AIN-93G containing 220 mg/kg iron and 0, 250, 500 or 750 mg ipriflavone per kg of food (n=4 or 5 per group) for 50 days, then sacrificed the animals for analysis of changes in gene expression by quantitative realtime RT-PCR, liver and spleen iron content, blood indices, and intestinal ferroportin expression. While producing less than a two-fold increase in liver hepcidin transcript levels, ipriflavone supplementation was associated with a significant decrease in liver iron content (mean±SE): 39.22±2.06 µg iron/g tissue, p=0.0033, and 44.10±2.58 µg iron/g tissue, p=0.0124, at 500 and 750 mg ipriflavone per kg of food, respectively, vs 57.77±3.39 µg iron/g tissue in mice that did not receive ipriflavone. Ferroportin expression detected in intestinal epithelial cells by immunohistochemistry was notably decreased in mice receiving ipriflavone: 66.6% and 80% of the animals receiving 500 and 750 mg/kg groups, respectively, exhibited decreased ferroportin staining versus 40% of the group not receiving ipriflavone. There was no significant difference in hemoglobin, hematocrit, or spleen iron among the groups. In conclusion, we have shown that orally administered ipriflavone is effective in decreasing liver iron content and intestinal ferroportin expression in vivo. Future experiments will evaluate ipriflavone’s effects on iron homeostasis and hematopoiesis in genetic models of iron overload disorders. Disclosures No relevant conflicts of interest to declare.

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Dietary Supplementation with Genistein Increases Hepcidin Expression in Wild Type Mice

Blood ◽

10.1182/blood.v120.21.3208.3208 ◽

2012 ◽

Vol 120 (21) ◽

pp. 3208-3208

Author(s):

Aileen W. Zhen ◽

Josephine Volovetz ◽

Paula G. Fraenkel

Keyword(s):

Iron Overload ◽

Iron Content ◽

Iron Absorption ◽

Small Scale ◽

Iron Release ◽

Liver Iron ◽

Transcript Levels ◽

Intestinal Iron Absorption ◽

Hepcidin Expression ◽

Liver Iron Content

Abstract Abstract 3208 Iron overload is an important cause of morbidity and death in patients with hemoglobinopathies, transfusion-dependent anemias, and hereditary hemochromatosis. As humans have no means of excreting iron, regulation of iron homeostasis depends on limiting intestinal iron absorption and optimizing iron release from macrophages to developing erythrocytes. Hepcidin, a peptide hormone produced in the liver, modulates intestinal iron absorption and macrophage iron release via effects on ferroportin. Hepcidin is a potential drug target for patients with iron overload syndromes because its levels are inappropriately low in these individuals. We conducted a small-scale chemical screen and found that the isoflavone genistein, a major dietary component of soybeans, enhanced Hepcidin transcript levels in zebrafish embryos. Furthermore genistein treatment increased Hepcidin transcript levels and Hepcidin promoter activity in human hepatocytes (HepG2 cells) in a Stat3 and Smad4-dependent manner. To evaluate genistein's effect in a mammalian model, we placed groups of 4 four-week old male C57BL/6 mice on an iron-sufficient, low soy diet (AIN93G containing 35 mg of iron/kg) supplemented with 0, 250, or 500 mg of genistein per kg of food for 7 weeks, and then sacrificed the animals for analysis. Plasma genistein levels (mean±SE) at the time of sacrifice were 0.015±0.015, 0.52±0.173, and 2.07±0.65 micromolar, respectively. Compared to mice not treated with genistein, the 250 mg/kg dose produced a significant increase in hepatic Hepcidin (HAMP1) transcript levels (1.49±0.10 vs 0.93±0.10, p=0.01), while the 500 mg/kg dose did not. Although liver iron content, spleen iron content, and weight gain were not significantly different among the groups, the ratio of Hepcidin expression to liver iron content was significantly increased in the animals treated with genistein 250 mg/kg compared to controls (0.013±0.0009 vs 0.0074±0.00068, p=0.0068). In conclusion, genistein is the first orally administered small molecule experimental drug shown to increase Hepcidin transcript levels in vivo. Future experiments will evaluate the effects of genistein on genetic models of iron overload syndromes. Disclosures: No relevant conflicts of interest to declare.

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Faculty Opinions recommendation of Association of iron overload with allogeneic hematopoietic cell transplantation outcomes: a prospective cohort study using R2-MRI-measured liver iron content.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.718095216.793482981 ◽

2013 ◽

Author(s):

André Tichelli

Keyword(s):

Cohort Study ◽

Iron Overload ◽

Cell Transplantation ◽

Prospective Cohort Study ◽

Iron Content ◽

Prospective Cohort ◽

Hematopoietic Cell Transplantation ◽

Liver Iron ◽

Liver Iron Content ◽

Transplantation Outcomes

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Magnetic Ressonance Imaging (MRI) in the Evaluation of Iron Overload in Patients with Beta Thalassaemia. The Brazilian National Program Preliminary Results.

Blood ◽

10.1182/blood.v106.11.3825.3825 ◽

2005 ◽

Vol 106 (11) ◽

pp. 3825-3825

Author(s):

Nelson Hamerschlak ◽

Laercio Rosemberg ◽

Alexandre Parma ◽

Fernanda F. Assir ◽

Frederico R. Moreira ◽

...

Keyword(s):

Iron Overload ◽

Ventricular Function ◽

Iron Content ◽

Chelation Therapy ◽

Iron Concentration ◽

Iron Chelation ◽

Inverse Correlation ◽

Liver Iron ◽

Liver Iron Content ◽

Cooperative Program

Abstract Magnetic Ressonance Imaging (MRI) using T2 star (T2*) tecnique appears to be a very useful method for monitoring iron overload and iron chelation therapy in thalassaemia. In Brazil, we have around 400 thalassaemic major patients all over the country. They were treated with hipertransfusion protocols and desferroxamine and/or deferiprone chelation. We developed a cooperative program with the Brazilian Thalassaemic Patients Association (ABRASTA) in order to developT2* tecnique in Brazil to submit brazilian patients to an annual iron overload monitoring process with MRI.. We performed the magnetic ressonance T2* using GE equipment (GE, Milwaukee USA), with validation to chemical estimation of iron in patients undergoing liver biopsy. Until now, 60 patients were scanned, median age=23,2 (12–54); gender: 18 male (30%) and 42 female (70%). The median ferritin levels were 2030 ng/ml (Q1=1466; Q3=3296). As other authors described before, there was a curvilinear inverse correlation between iron concentration by biopsy, liver T2*(r=0,92) and also there were a correlation with ferritin levels. We also correlated myocardial iron measured by T2* with ventricular function.. As miocardial iron increased, there was a progressive decline in ejection fraction and no significant correlation was found between miocardial T2* and the ferritin levels. Liver iron content can be predicted by ferritin levels. On the other hand, cardiac disfunction is the most important cause of mortality among thalassaemic patients. Since Miocardio iron content cannot be predicted from serum ferritin or liver iron, and ventricular function can only detect those with advance disease, intensification and combination of chelation therapy, guided by T2* MRI tecnique should reduce mortality from the reversible cardiomyopathy among thalassaemic patients.

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Comparing the Value of Serum Ferritin, Transfusion History and Magnetic Resonance Imaging for the Prediction of Iron Overload In MDS and AML Patients Undergoing Allogeneic Stem Cell Transplantation.

Blood ◽

10.1182/blood.v116.21.3493.3493 ◽

2010 ◽

Vol 116 (21) ◽

pp. 3493-3493

Author(s):

Martin Wermke ◽

Jan Moritz Middeke ◽

Nona Shayegi ◽

Verena Plodeck ◽

Michael Laniado ◽

...

Keyword(s):

Iron Overload ◽

Serum Ferritin ◽

Iron Content ◽

Iron Concentration ◽

Transferrin Saturation ◽

Resonance Imaging ◽

Liver Iron Concentration ◽

Liver Iron ◽

Liver Iron Content ◽

Transfusion History

Abstract Abstract 3493 An increased risk for GvHD, infections and liver toxicity after transplant has been attributed to iron overload (defined by serum ferritin) of MDS and AML patients prior to allogeneic hematopoietic stem cell transplantation (allo-HSCT). Nevertheless, the reason for this observation is not very well defined. Consequently, there is a debate whether to use iron chelators in these patients prior to allo-HSCT. In fact, serum ferritin levels and transfusion history are commonly used to guide iron depletion strategies. Both parameters may inadequately reflect body iron stores in MDS and AML patients prior to allo-HSCT. Recently, quantitative magnetic resonance imaging (MRI) was introduced as a tool for direct measurement of liver iron. We therefore aimed at evaluating the accurateness of different strategies for determining iron overload in MDS and AML patients prior to allo-HSCT. Serologic parameters of iron overload (ferritin, iron, transferrin, transferrin saturation, soluble transferrin receptor) and transfusion history were obtained prospectively in MDS or AML patients prior to allo-SCT. In parallel, liver iron content was measured by MRI according to the method described by Gandon (Lancet 2004) and Rose (Eur J Haematol 2006), respectively. A total of 20 AML and 9 MDS patients (median age 59 years, range: 23–74 years) undergoing allo-HSCT have been evaluated so far. The median ferritin concentration was 2237 μg/l (range 572–6594 μg/l) and patients had received a median of 20 transfusions (range 6–127) before transplantation. Serum ferritin was not significantly correlated with transfusion burden (t = 0.207, p = 0.119) but as expected with the concentration of C-reactive protein (t = 0.385, p = 0.003). Median liver iron concentration measured by MRI was 150 μmol/g (range 40–300 μmol/g, normal: < 36 μmol/g). A weak but significant correlation was found between liver iron concentration and ferritin (t = 0.354; p = 0.008). The strength of the correlation was diminished by the influence of 5 outliers with high ferritin concentrations but rather low liver iron content (Figure 1). The same applied to transfusion history which was also only weakly associated with liver iron content (t = 0.365; p = 0.007). Levels of transferrin, transferrin saturation, total iron and soluble transferrin receptor did not predict for liver iron concentration. Our data suggest that serum ferritin or transfusion history cannot be regarded as robust surrogates for the actual iron overload in MDS or AML patients. Therefore we advocate caution when using one of these parameters as the only trigger for chelation therapy or as a risk-factor to predict outcome after allo-HSCT. Figure 1. Correlation of Liver iron content with Ferritin. Figure 1. Correlation of Liver iron content with Ferritin. Disclosures: No relevant conflicts of interest to declare.

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Association of Iron Overload with Survival and Complications in Allogeneic Hematopoietic Cell Transplant Recipients: Prospective Cohort Study Using R2-MRI Measured Liver Iron Content

Blood ◽

10.1182/blood.v120.21.1961.1961 ◽

2012 ◽

Vol 120 (21) ◽

pp. 1961-1961

Author(s):

Bryan J Trottier ◽

Todd E. Defor ◽

Linda J Burns ◽

Sarah Cooley ◽

Navneet S. Majhail

Keyword(s):

Iron Overload ◽

Research Funding ◽

Immune Reconstitution ◽

Cell Transplant ◽

Hematopoietic Cell Transplant ◽

Liver Iron ◽

Allogeneic Hct ◽

Liver Iron Content ◽

Significant Difference ◽

The Impact

Abstract Abstract 1961 Elevated pre-transplant ferritin levels have been associated with increased mortality and transplant-related complications in hematopoietic cell transplant (HCT) recipients. However, attempts to define the impact of iron overload on transplant outcomes using ferritin are confounded by its lack of specificity. Using liver magnetic resonance imaging (R2-MRI) to quantify liver iron content (LIC), we designed a prospective cohort study to determine the impact of iron overload on outcomes following allogeneic HCT. Our primary study objective was to determine the impact of pre-transplant iron overload on overall survival (OS); secondary objectives included cumulative incidence of non-relapse mortality (NRM) and post-HCT complications. Adult patients with hematologic malignancies being considered for allogeneic HCT were recruited for this study. Enrolled patients underwent baseline, pre-transplant ferritin measurements; patients with ferritin levels > 500 ng/ml had LIC quantified using liver R2-MRI. Patients were defined as no-iron overload (ferritin ≤ 500 or LIC ≤ 1.8 mg/gdw) and iron overload (LIC > 1.8). Of the 112 patients recruited for the study, 24 were excluded (disease progression=12, unable to complete MRI=9, transplant delays due to pre-HCT complications=3) and 88 were included in the final analysis (no-iron overload=28, iron overload=60). Four patients had ferritin >500, but on MRI had LIC ≤ 1.8 and were included in the no-iron overload group. Median ferritin in the two groups was 290 (range, 52–2023) and 1732 (range, 510–7137), respectively. The median LIC in the iron overload group was 4.3 (range, 1.9–25.4). Baseline ferritin moderately correlated with LIC (Spearman's R=0.58). There was no significant difference in recipient age, conditioning intensity, graft source, or HCT comorbidity index scores between the two groups. Patients with iron overload were more likely to have acute leukemia (55% vs 15%) and less likely to have high risk disease (40 vs 75%). We observed no significant difference in OS, NRM, relapse, acute or chronic graft-versus-host disease, organ failure, bacterial infections, viral infections, or fungal infections among patients without and with iron overload (see Table). We also found no difference in the composite endpoint of NRM, any infection, organ failure or hepatic veno-occlusive disease (1 yr cumulative incidence 71% vs 80%, P=0.44). In multivariate analyses that adjusted for other important prognostic variables, iron overload status did not impact risks of overall mortality (relative risk 2.3 (0.9–5.9) for iron overload vs. no-iron overload). We also evaluated outcomes based on an LIC threshold of ≤ 5 vs > 5 and observed similar results (see Table). Immune reconstitution studies were done in 55 patients at 3, 6 and/or 12 months post-HCT (no-iron overload=19, iron overload=36). On generalized linear mixed modeling, presence of iron overload was not associated with delay in recovery of absolute lymphocyte count, total NK cells, total T cells, CD4 cells, CD8 cells, or regulatory T cells. In conclusion, we did not find an association between pre-transplant iron-overload defined by R2-MRI measured LIC and OS, NRM, complications or immune reconstitution after allogeneic HCT in adults. Pre-transplant ferritin levels only moderately correlated with LIC. Future studies of iron overload in HCT should consider LIC to define iron overload instead of ferritin. Table. Outcomes by Iron-Overload Status Prob (95% CI) Prob (95% CI) P-value Ferritin ≤ 500 or LIC ≤ 1.8 LIC > 1.8 N 28 60 2 yr OS 78% (57–90) 58% (44–70) 0.12 2 yr NRM 18% (4–33) 21% (10–32) 0.91 1 yr Bacterial Infection 11% (0–22) 13% (5–22) 0.72 1 yr Fungal Infection 7% (0–17) 12% (4–20) 0.49 LIC ≤ 5.0 LIC > 5.0 N 65 23 2 yr OS 62% (49–73) 73% (49–87) 0.42 2 yr NRM 20% (10–30) 19% (3–35) 0.82 1 yr Bacterial Infection 12% (4–20) 13% (0–27) 0.98 1 yr Fungal Infection 12% (4–20) 4% (0–12) 0.28 Disclosures: Burns: Novartis Pharmaceuticals: Research Funding. Majhail:Novartis Pharmaceuticals: Research Funding.

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A Screen for Small Molecules That Regulate Hepcidin Expression

Blood ◽

10.1182/blood.v120.21.611.611 ◽

2012 ◽

Vol 120 (21) ◽

pp. 611-611

Author(s):

Josephine Volovetz ◽

Aileen W. Zhen ◽

Vera Gaun ◽

Bonnie Patchen ◽

Paula G. Fraenkel

Keyword(s):

Iron Overload ◽

Cell Viability ◽

Small Molecules ◽

Unknown Function ◽

Cell Biology ◽

Kinase Inhibitor ◽

Conflicts Of Interest ◽

Iron Release ◽

Hepcidin Expression ◽

Standard Deviations

Abstract Abstract 611 Hepcidin, a peptide hormone produced in the liver, decreases intestinal iron absorption and macrophage iron release via effects on ferroportin. Hepcidin is a potential drug target for patients with iron overload syndromes because its levels are inappropriately low in these individuals. To generate a tool for identifying small molecules that modulate Hepcidin expression, we stably transfected human hepatocytes (HepG2) cells with a reporter construct containing 3 kilobases of the human Hepcidin promoter upstream of a firefly reporter gene. We then used high throughput methods to screen 10,360 chemicals in duplicate from the Harvard Institute of Chemistry and Cell Biology library for their effect on Hepcidin expression and cell viability. Regulators were identified as chemicals that caused a change >3 standard deviations above or >1.5 standard deviations below the mean of the other chemicals (z-score >3 or <-1.5), while not adversely affecting cell viability, quantified by a nonlytic fluorescence assay. Using these criteria, we identified 32 small molecules that upregulated and 3 that downregulated Hepcidin expression. Functional classification of the positive regulators indicated: 4 anti-inflammatory agents, 4 antimicrobials, 6 antineoplastic drugs, 6 kinase inhibitors, and 12 with other or unknown function. Of the positive modulators, two were flavones, consistent with our prior discovery that the isoflavone genistein upregulates Hepcidin expression. Of the negative regulators, one was a kinase inhibitor and two were of unknown function. Experiments are underway to characterize the mechanism of action of these regulators. The best candidates will subsequently be tested in mouse models of iron overload syndromes with the intention of developing new therapies for diseases in which Hepcidin is inappropriately regulated. Disclosures: No relevant conflicts of interest to declare.

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Serum Ferritin Predicts Liver but Not Cardiac Iron Burden by Noninvasive MRI in Sickle Cell Disease (SCD.

Blood ◽

10.1182/blood.v112.11.1421.1421 ◽

2008 ◽

Vol 112 (11) ◽

pp. 1421-1421 ◽

Cited By ~ 1

Author(s):

Robert I. Liem ◽

Cynthia Rigsby ◽

Richard J. Labotka ◽

Andrew DeFreitas ◽

Alexis A. Thompson

Keyword(s):

Iron Overload ◽

Serum Ferritin ◽

Iron Content ◽

Iron Loading ◽

Cell Disease ◽

Liver Iron ◽

Cardiac Iron ◽

Liver Iron Content ◽

The Mean

Abstract BACKGROUND: Assumptions about iron loading as well as the utility of ferritin to predict transfusional iron overload among individuals with sickle cell disease (SCD) are largely based on extrapolation from data generated in patients with thalassemia major (TM). Yet recent studies suggest the natural history of iron overload in patients with SCD differs significantly from chronically transfused patients with TM. We sought to evaluate the extent of myocardial and hepatic siderosis using noninvasive imaging in chronically transfused patients with SCD and examine its clinical associations, including relationship to long-term trends in serum ferritin, transfusion history, chelation status and markers of hemolysis and inflammation. METHODS: We evaluated 17 subjects (mean age 15±3.6 yrs, range 9 to 20). The mean transfusion duration was 7.3±3.6 yrs (range 2 to 15). Thirteen (76%) patients were on chelation with deferasirox at the time of screening; 4 were not on chelation Rx. MRI T2*/R2* of the heart and liver using a multiple gradient echo sequence was performed on a single 1.5T GE scanner. Hepatic iron concentration (HIC) values were predicted from liver R2* values. RESULTS: Mean HIC in subjects was 9.9±6.7 mg/gm liver dry weight (range 2.5 to 20.8) and was ≥15 mg/gm in 6/17 (35%) subjects. The mean long-term serum ferritin (past 5 yrs, or duration of transfusion if < 5yrs) was 2318±1122 ng/mL (range 541 to 4225). Using Pearson’s correlation coefficient, we observed a significant relationship between HIC and ferritin (r=0.765, p=<0.001). We generated a receiver operator characteristic (ROC) curve to assess the utility of ferritin as a predictor of elevated HIC, using a threshold HIC thought to predict serious iron-related complications. A ferritin cut-off value ≥2164 ng/mL correctly identified 80% of cases of HIC ≥15 mg/gm (AUC 0.96, p=0.003) in our subjects with 83% sensitivity and 73% specificity. Despite markedly elevated HIC and ferritin values in some subjects, none had myocardial siderosis. All 17 subjects had cardiac MRI T2* values in the normal range > 25 ms. Cardiac iron load measured by T2* did not correlate with HIC or serum ferritin. We examined C-reactive protein (CRP) and B-type natriuretic peptide (BNP) as markers for inflammation and myocardial strain, respectively, in our subjects but neither demonstrated a significant relationship to ferritin or MRI findings. BNP, however, did correlate modestly with both age (r=−0.574, p=0.013) and left ventricular ejection fraction on cardiac MRI (r=0.510, p=0.036). A subset of subjects (n=8) had histologic iron measurements by percutaneous liver biopsy (LBx) within 6 months of MRI. While liver iron content by LBx correlated significantly with HIC by MRI (r=0.759, p=0.03), liver iron content by LBx did not correlate with ferritin (r=0.312, p=0.452). CONCLUSION: We found that serum ferritin is a good predictor of liver iron by MRI R2*, and that long term ferritin values ≥2164 ng/mL predict significant hepatic iron overload as assessed by this noninvasive method. We did not observe appreciable cardiac iron loading in our subjects with SCD, which otherwise might have been predicted by elevated HIC alone, as in individuals with TM. These data suggest that reliable, long term surveillance of transfusion-induced iron overload in SCD may be achieved using serum ferritin and HIC by MRI R2* as surrogate markers of hepatic siderosis rather than relying on liver iron content measured invasively by LBx. Also, previously determined thresholds for significant cardiac iron loading in TM, based on degree of hepatic siderosis, may not be applicable in SCD. Further investigation into alternative mechanisms of iron loading or distribution in these related but distinct disorders is warranted.

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The Effect of Supplemental Ascorbate on Defersirox Iron Chelation In the Iron-Loaded Gerbil

Blood ◽

10.1182/blood.v116.21.2059.2059 ◽

2010 ◽

Vol 116 (21) ◽

pp. 2059-2059

Author(s):

Maya Otto-Duessel ◽

Casey Brewer ◽

Aleya Hyderi ◽

Jens Lykkesfeldt ◽

Ignacio Gonzalez-Gomez ◽

...

Keyword(s):

Iron Overload ◽

Iron Content ◽

Iron Concentration ◽

Iron Chelation ◽

Iron Dextran ◽

Iron Loading ◽

Liver Iron ◽

Cardiac Iron ◽

Liver Iron Content ◽

Wet Weight

Abstract Abstract 2059 Introduction: Iron dextran injections are often used to induce iron overload in rodents, for the purposes of assessing iron chelation therapy. In gerbils, we have previously described that deferasirox therapy preferentially clears hepatocellular iron when compared with reticuloendothelial stores. Ascorbate deficiency, which is common in humans with iron overload, produces similar profound disparities between reticuloendothelial and parenchymal iron stores. We postulated that iron-induced ascorbate deficiency might be exaggerating reticuloendothelial iron retention in gerbils receiving deferasirox therapy. This study examined the effect of supplemental ascorbate on spontaneous iron loss and deferasirox chelation efficiency in the iron-dextran loaded gerbil. Methods: 48 female gerbils underwent iron dextran loading at 200 mg/kg/week for 10 weeks. Sixteen animals were sacrificed at 11 weeks to characterize iron loading; eight were on standard rodent chow and eight had chow supplemented with 2250 ppm of ascorbate. 32 additional animals that were not ascorbate supplemented during iron loading transitioned into the chelation phase. Half were subsequently placed on ascorbate supplemented chow and both groups were assigned to receive either deferasirox 100 mg/kg/day five days per week or sham chelation. Animals received iron chelation for twelve weeks. Liver histology was assessed using H & E and Prussian blue stains. Iron loading was ranked and graded on a five-point scale by an experienced pathologist screened to the treatment arm. Iron quantitation in liver and heart was performed by atomic absorption. Results: Table 1 one summarizes the findings. During iron dextran loading, ascorbate supplementation lowered wet weight liver iron concentration but not liver iron content suggesting primarily changes in tissue water content. Spontaneous iron losses were insignificant, regardless of ascorbate therapy. Deferasirox lowered liver iron content 56% (4.7% per week) in animals without ascorbate supplementation and 48.3% (4.0% per week) with ascorbate supplementation (p=NS). Cardiac iron loading, unloading and redistribution were completely unaffected by ascorbate supplementation. Spontaneous iron redistribution was large (1.9% – 2.3% per week). Deferasirox chelation did not lower cardiac iron to a greater degree than spontaneous cardiac iron redistribution. Histologic grading paralleled tissue wet weight iron concentrations. Ascorbate treatment lowered the rank and absolute iron score in liver during iron loading (p=0.003) and there was a trend toward lower iron scoring in sham treated animals (p=0.13). Ascorbate had no effect on histological score or relative compartment distributions of iron in deferasirox chelated animals (p=0.5). Ascorbate supplementation was sufficient to increase total plasma ascorbate levels from 25 ± 12.2 uM to 38.4 ± 11 uM at 10 weeks (p=0.03). In the liver, ascorbate increased from 1203 ± 212 nmol/g of tissue to 1515 ± 194 nmol/g of tissue (p=0.01) with supplementation. No significant change in total ascorbate was observed in the heart. Discussion: We hypothesized that ascorbate supplementation might improve reticuloendothelial iron accessibility to deferasirox by facilitating redox cycling. Although gerbils synthesize their own ascorbate, supplementation was able to raise both serum and hepatic total ascorbate levels. However, increasing ascorbate did not change either the amount or distribution of tissue iron in deferasirox-treated animals. Disclosures: Nick: Novartis: Employment. Wood:Novartis: Research Funding; Ferrokin Biosciences: Consultancy.

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