Low-dose erythropoietin improves cardiac function in experimental heart failure without increasing haematocrit

Role of Erythropoiesis-Stimulating Agents in Cardiovascular Protection in CKD Patients: Reappraisal of Their Impact and Mechanisms

Erythropoiesis-stimulating agents (ESAs) have markedly reduced the need for blood transfusion for renal anemia and are included in standard therapies for patients with chronic kidney disease (CKD). Various protective effects of ESAs on the cardiovascular system have been discovered through basic research, and the effects have received much attention because the rates of cardiovascular events and mortality are high in CKD patients. However, randomized clinical trials did not provide strong evidence that ESAs exert cardioprotection in humans, including CKD patients. It is difficult to assess the cardioprotective effects of ESAs in CKD patients through the clinical data that has been reported to date because the relationship between hemoglobin level rather than ESA dose and cardiovascular event rates was examined in most studies. Interestingly, recent studies using a rat model of CKD showed that the infarct size-limiting effect of an ESA was lost when its dose was increased to a level that normalized blood hemoglobin levels, suggesting that the optimal dose of an ESA for myocardial protection is less than the dose required to normalize hemoglobin levels. Furthermore, animal models of traditional coronary risk factors or comorbidities were resistant to the cardioprotective effects of ESAs because of interruptions in signal-mediated mechanisms downstream of erythropoietin receptors. In this review, we briefly discuss basic and clinical data on the impact of anemia on coronary and systemic circulation, the effects of CKD on the cardiovascular system, and the multiple pharmacological actions of ESAs to examine whether the ESAs that are prescribed for renal anemia exert any cardioprotection in patients with CKD.

The erythropoietin receptor expressed in skeletal muscle is essential for mitochondrial biogenesis and physiological exercise

Erythropoietin (EPO) is a haematopoietic hormone that regulates erythropoiesis, but the EPO-receptor (EpoR) is also expressed in non-haematopoietic tissues. Stimulation of the EpoR in cardiac and skeletal muscle provides protection from various forms of pathological stress, but its relevance for normal muscle physiology remains unclear. We aimed to determine the contribution of the tissue-specific EpoR to exercise-induced remodelling of cardiac and skeletal muscle. Baseline phenotyping was performed on left ventricle and m. gastrocnemius of mice that only express the EpoR in haematopoietic tissues (EpoR-tKO). Subsequently, mice were caged in the presence or absence of a running wheel for 4 weeks and exercise performance, cardiac function and histological and molecular markers for physiological adaptation were assessed. While gross morphology of both muscles was normal in EpoR-tKO mice, mitochondrial content in skeletal muscle was decreased by 50%, associated with similar reductions in mitochondrial biogenesis, while mitophagy was unaltered. When subjected to exercise, EpoR-tKO mice ran slower and covered less distance than wild-type (WT) mice (5.5 ± 0.6 vs. 8.0 ± 0.4 km/day, p < 0.01). The impaired exercise performance was paralleled by reductions in myocyte growth and angiogenesis in both muscle types. Our findings indicate that the endogenous EPO-EpoR system controls mitochondrial biogenesis in skeletal muscle. The reductions in mitochondrial content were associated with reduced exercise capacity in response to voluntary exercise, supporting a critical role for the extra-haematopoietic EpoR in exercise performance.

Application of Erythropoietin in Chronic Heart Failure Treatment

Heart Failure (HF) is recognized as an important public health concern worldwide, especially in developed countries, due to its high rate of morbidity and mortality. Although new pharmacological and non-pharmacological agents have improved the clinical sequelae of HF in patients, its mortality remains high, especially among the elderly. Erythropoietin (EPO), a glycoprotein, besides its traditional role in promoting erythropoiesis and production of erythroid progenitors, its beneficial role in reducing infarct area and improving heart function through EPO-induced antiapoptotic and antioxidant effects have been increasingly recognized. This review gathers the evidence to date about the effectiveness of EPO in HF patients. In addition to the growing evidence of EPO in the treatment of HF in the animal studies for improving cardiac function and infarct size, more clinical studies are needed to assess the role of EPO treatment in the management of HF.

Erythropoietin improves cardiovascular function in adult rats after acute hemorrhage

Erythropoietin (EPO) has been linked to cardioprotective effects. However, its effects during the aging process are little known. We investigated the effect of EPO administration on hemodynamic parameters, cardiac function, oxidative damage, and erythropoietin receptor (EPOR) expression pattern in the hypovolemic state. EPO was administered (1000 IU/kg/3 days) and then acute hemorrhage (20% blood loss) was induced in young and adult rats. There was no difference in plasmatic EPO in either age group. The hemodynamic basal condition was similar, without alterations in renal function and hematocrit, in both age groups. After bleeding, both EPO-treated age groups had increased blood pressure at the end of the experimental protocol, being greater in adult animals. EPO attenuated the tachycardic effect. Ejection fraction and fractional shortening were higher in adult EPO-treated rats subjected to hemorrhage. In the left ventricle, young and adult EPO-treated rats subjected to bleeding showed an increased EPOR expression. A different EPOR expression pattern was observed in the adult right atrial tissue, compared with young animals. EPO treatment decreased oxidative damage to lipids in both age groups. EPO treatment before acute hemorrhage improves cardiovascular function during the aging process, which is mediated by different EPOR pattern expression in the heart tissue.

Phosphorylation of signal transducer and activator of transcription 3 induced by hyperglycemia is different with that induced by lipopolysaccharide or erythropoietin via receptor‑coupled signaling in cardiac cells

The signal transducer and activator of transcription 3 (STAT3) is known to be involved in hypertrophy and fibrosis in cardiac dysfunction. The activation of STAT3 via the phosphorylation of STAT3 is required for the production of functional activity. It has been established that lipopolysaccharide (LPS)‑induced phosphorylation of STAT3 in cardiomyocytes primarily occurs through a direct receptor‑mediated action. This effect is demonstrated to be produced rapidly. STAT3 in cardiac fibrosis of diabetes is induced by high glucose through promotion of the STAT3‑associated signaling pathway. However, the time schedule for STAT3 activation between LPS and high glucose appears to be different. Therefore, the difference in STAT3 activation between LPS and hyperglycemia in cardiomyocytes requires elucidation. The present study investigated the phosphorylation of STAT3 induced by LPS and hyperglycemia in the rat cardiac cell line H9c2. Additionally, phosphorylation of STAT3 induced by erythropoietin (EPO) via receptor activation was compared. Then, the downstream signals for fibrosis, including the connective tissue growth factor (CTGF) and matrix metalloproteinase (MMP)‑9, were determined using western blotting, while the mRNA levels were quantified. LPS induced a rapid elevation of STAT3 phosphorylation in H9c2 cells within 30 min, similar to that produced by EPO. However, LPS or EPO failed to modify the mRNA level of STAT3, and/or the downstream signals for fibrosis. High glucose increased STAT3 phosphorylation to be stable after a long period of incubation. Glucose incubation for 24 h may augment the STAT3 expression in a dose‑dependent manner. Consequently, fibrosis‑associated signals, including CTGF and MMP‑9 protein, were raised in parallel. In the presence of tiron, an antioxidant, these changes by hyperglycemia were markedly reduced, demonstrating the mediation of oxidative stress. Therefore, LPS‑ or EPO‑induced STAT3 phosphorylation is different compared with that caused by high glucose in H9c2 cells. Sustained activation of STAT3 by hyperglycemia may promote the expression of fibrosis‑associated signals, including CTGF and MMP‑9, in H9c2 cells. Therefore, regarding the cardiac dysfunctions associated with diabetes and/or hyperglycemia, the identification of nuclear STAT3 may be more reliable compared with the assay of phosphorylated STAT3 in cardiac cells.

Cardiovascular Protection by Sodium Glucose Cotransporter 2 Inhibitors: Potential Mechanisms

The mechanism of action of empagliflozin in reducing the risk of adverse cardiovascular outcomes vs placebo in patients with type 2 diabetes mellitus and a high risk of cardiovascular disease in the Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients-Removing Excess Glucose (EMPA-REG OUTCOME) trial is currently unknown. An antiatherosclerotic effect is considered unlikely given the speed of the observed decrease in cardiovascular mortality. Hemodynamic effects, such as reductions in blood pressure and intravascular volume, and involving osmotic diuresis, may provide a more plausible explanation. Metabolic effects, such as cardiac fuel energetics, and hormonal effects, such as increased glucagon release, may also contribute to the results observed during EMPA-REG OUTCOME. This review discusses the main hypotheses suggested to date.

Cardiovascular Protection by Sodium Glucose Cotransporter 2 Inhibitors: Potential Mechanisms

The mechanism of action of empagliflozin in reducing the risk of adverse cardiovascular outcomes vs placebo in patients with type 2 diabetes mellitus and a high risk of cardiovascular disease in the Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients-Removing Excess Glucose (EMPA-REG OUTCOME) trial is currently unknown. An antiatherosclerotic effect is considered unlikely given the speed of the observed decrease in cardiovascular mortality. Hemodynamic effects, such as reductions in blood pressure and intravascular volume, and involving osmotic diuresis, may provide a more plausible explanation. Metabolic effects, such as cardiac fuel energetics, and hormonal effects, such as increased glucagon release, may also contribute to the results observed during EMPA-REG OUTCOME. This review discusses the main hypotheses suggested to date.

Prognostic significance of endogenous erythropoietin in long-term outcome of patients with acute decompensated heart failure

AIMS

Although previous reports suggest that an elevated endogenous erythropoietin (EPO) level is associated with worse clinical outcomes in chronic heart failure (HF) patients, the prognostic implication of EPO in patients with acute decompensated HF (ADHF) and underlying mechanisms of the high EPO level in severe HF patients who have a poor prognosis remain unclear.

METHODS AND RESULTS

We examined 539 consecutive ADHF patients with EPO measurement on admission from our registry. During a median follow-up period of 329 days, a higher EPO level on admission was independently associated with worse clinical outcomes [hazard ratio (HR) 1.25, 95% confidence interval (CI) 1.06-1.48, P = 0.008], and haemoglobin level was the strongest determinant of EPO level (P < 0.001), whereas estimated glomerular filtration rate (eGFR) was not significant in multivariate regression analysis. In the anaemic subgroup of 318 patients, a higher EPO level than expected on the basis of their haemoglobin level was related to increased adverse events (HR 1.63, 95% CI 1.05-2.49, P = 0.028). Moreover, estimated plasma volume excess rate was positively associated with EPO level (P = 0.003), and anaemic patients with a higher than expected EPO level tended to have a higher estimated plasma volume excess rate and plasma lactate level, and lower systemic oxygen saturation level with the preservation of the reticulocyte production index than those with a lower than expected EPO level.

CONCLUSION

A high EPO level predicts long-term worse clinical outcomes in ADHF patients, independent of anaemia and impaired renal function. Anaemia and hypoxia due to severe congestion may synergistically contribute to a high EPO level in high-risk HF patients.

In-vivo monitoring of erythropoietin treatment after myocardial infarction in mice with [⁶⁸Ga]Annexin A5 and [¹⁸F]FDG PET

BACKGROUND

Several studies substantiate the cardioprotective effects of erythropoietin (EPO). Our goal was to quantify the effects of EPO treatment on the early expression of the apoptosis marker phosphatidylserine as well as on the left ventricular volumes and function by means of small animal PET.

METHODS AND RESULTS

Myocardial infarction (MI) was induced in C57BL/6 mice. Animals were assigned to saline or EPO groups and underwent Annexin PET (day 2) and gated FDG PET (days 6 and 30). Annexin uptake was significantly higher in the infarction than in remote myocardium, with no differences between treatment groups. Infarct size showed a slight decrease in the EPO group and a slight increase in the controls, which did not reach statistical significance. Follow-up analyses revealed a significant increase of end-diastolic and end-systolic volumes in the EPO group, in which a stable left ventricular ejection fraction (LVEF) was maintained.

CONCLUSION

We find that deleterious effects of EPO can outweigh cardioprotective effects. The present EPO treatment did not significantly reduce apoptosis after MI, but seemingly provoked significant myocardial dilation while maintaining a stable LVEF. Molecular mechanisms of EPO treatment may need further elucidation to optimize therapy regimens.

Systemic administration of erythropoietin inhibits retinopathy in RCS rats

Objective

Royal College of Surgeons (RCS) rats develop vasculopathy as photoreceptors degenerate. The aim of this study was to examine the effect of erythropoietin (EPO) on retinopathy in RCS rats.

Methods

Fluorescein angiography was used to monitor retinal vascular changes over time. Changes in retinal glia and vasculature were studied by immunostaining. To study the effects of EPO on retinal pathology, EPO (5000 IU/kg) was injected intraperitoneally in 14 week old normal and RCS rats twice a week for 4 weeks. Changes in the retinal vasculature, glia and microglia, photoreceptor apoptosis, differential expression of p75 neurotrophin receptor (p75^NTR), pro-neurotrophin 3 (pro-NT3), tumour necrosis factor-α (TNFα), pigment epithelium derived factor (PEDF) and vascular endothelial growth factor-A (VEGF-A), the production of CD34⁺ cells and mobilization of CD34⁺/VEGF-R2⁺ cells as well as recruitment of CD34⁺ cells into the retina were examined after EPO treatment.

Results

RCS rats developed progressive capillary dropout and subretinal neovascularization which were accompanied by retinal gliosis. Systemic administration of EPO stabilized the retinal vasculature and inhibited the development of focal vascular lesions. Further studies showed that EPO modulated retinal gliosis, attenuated photoreceptor apoptosis and p75^NTR and pro-NT3 upregulation, promoted the infiltration of ramified microglia and stimulated VEGF-A expression but had little effect on TNFα and PEDF expression. EPO stimulated the production of red and white blood cells and CD34⁺ cells along with effective mobilization of CD34⁺/VEGF-R2⁺ cells. Immunofluorescence study demonstrated that EPO enhanced the recruitment of CD34⁺ cells into the retina.

Conclusions

Our results suggest that EPO has therapeutic potentials in treatment of neuronal and vascular pathology in retinal disease. The protective effects of EPO on photoreceptors and the retinal vasculature may involve multiple mechanisms including regulation of retinal glia and microglia, inhibition of p75^NTR-pro-NT3 signaling together with stimulation of production and mobilization of bone marrow derived cells.

Erythropoietin in cardiac disease: effective or harmful?

Discovered as the primary regulator of erythropoiesis, erythropoietin (EPO) is involved in a broad variety of processes that play a major role in cardiovascular diseases. In particular, the antiapoptotic and pro-angiogenic properties of EPO have prompted a growing interest in the use of EPO for the treatment of myocardial infarction and heart failure. In a variety of myocardial ischemic injury animal models, EPO administration has been shown to acutely reduce infarct size, thereby preserving ventricular function. In addition, cardiac long-term effects of EPO, such as prevention of ventricular remodeling and heart failure, have been described. In recent years, several trials have tested the effects of recombinant human erythropoietin (rhEPO) administration in patients with myocardial infarction and chronic heart failure, in the attempt to translate the cardioprotection found in experimental models to human patients. In view of the generally controversial findings, in this updated review we provide an overview of the results of the most recent trials that investigated the role of erythropoiesis-stimulating agents (ESAs), including rhEPO and its analogue darbepoetin, in the treatment of acute myocardial infarction and heart failure. The problems related to safety and tolerability of ESA therapy are also discussed. Our analysis of the available literature demonstrates that the results of clinical studies in patients with cardiac disease are not uniform and the conclusions are contradictory. Further larger prospective studies are required to test clinical efficacy and safety of EPO.

Erythropoietin and the heart: physiological effects and the therapeutic perspective

Erythropoietin (Epo) has been thought to act exclusively on erythroid progenitor cells. The identification of Epo receptor (EpoR) in non-haematopoietic cells and tissues including neurons, astrocytes, microglia, immune cells, cancer cell lines, endothelial cells, bone marrow stromal cells, as well as cells of myocardium, reproductive system, gastrointestinal tract, kidney, pancreas and skeletal muscle indicates that Epo has pleiotropic actions. Epo shows signals through protein kinases, anti-apoptotic proteins and transcription factors. In light of interest of administering recombinant human erythropoietin (rhEpo) and its analogues for limiting infarct size and left ventricular (LV) remodelling after acute myocardial infarction (AMI) in humans, the foremost studies utilising rhEpo are reviewed. The putative mechanisms involved in Epo-induced cardioprotection are related to the antiapoptotic, anti-inflammatory and angiogenic effects of Epo. Thus, cardioprotective potentials of rhEpo are reviewed in this article by focusing on clinical applicability. An overview of non-haematopoietic Epo analogues, which are a reliable alternative to the classic EpoR agonists and may prevent undesired side effects, is also provided.

Baseline characteristics of patients in the Reduction of Events with Darbepoetin alfa in Heart Failure trial (RED-HF)

AIMS

This report describes the baseline characteristics of patients in the Reduction of Events with Darbepoetin alfa in Heart Failure trial (RED-HF) which is testing the hypothesis that anaemia correction with darbepoetin alfa will reduce the composite endpoint of death from any cause or hospital admission for worsening heart failure, and improve other outcomes.

METHODS AND RESULTS

Key demographic, clinical, and laboratory findings, along with baseline treatment, are reported and compared with those of patients in other recent clinical trials in heart failure. Compared with other recent trials, RED-HF enrolled more elderly [mean age 70 (SD 11.4) years], female (41%), and black (9%) patients. RED-HF patients more often had diabetes (46%) and renal impairment (72% had an estimated glomerular filtration rate < 60 mL/min/1.73 m2). Patients in RED-HF had heart failure of longer duration [5.3 (5.4) years], worse NYHA class (35% II, 63% III, and 2% IV), and more signs of congestion. Mean EF was 30% (6.8%). RED-HF patients were well treated at randomization, and pharmacological therapy at baseline was broadly similar to that of other recent trials, taking account of study-specific inclusion/exclusion criteria. Median (interquartile range) haemoglobin at baseline was 112 (106-117) g/L.

CONCLUSION

The anaemic patients enrolled in RED-HF were older, moderately to markedly symptomatic, and had extensive co-morbidity.

Skeletal muscle alterations and exercise performance decrease in erythropoietin-deficient mice: a comparative study

BACKGROUND

Erythropoietin (EPO) is known to improve exercise performance by increasing oxygen blood transport and thus inducing a higher maximum oxygen uptake (VO2max). Furthermore, treatment with (or overexpression of) EPO induces protective effects in several tissues, including the myocardium. However, it is not known whether EPO exerts this protective effect when present at physiological levels. Given that EPO receptors have been identified in skeletal muscle, we hypothesized that EPO may have a direct, protective effect on this tissue. Thus, the objectives of the present study were to confirm a decrease in exercise performance and highlight muscle transcriptome alterations in a murine EPO functional knock-out model (the EPO-d mouse).

METHODS

We determined VO2max peak velocity and critical speed in exhaustive runs in 17 mice (9 EPO-d animals and 8 inbred controls), using treadmill enclosed in a metabolic chamber. Mice were sacrificed 24h after a last exhaustive treadmill exercise at critical speed. The tibialis anterior and soleus muscles were removed and total RNA was extracted for microarray gene expression analysis.

RESULTS

The EPO-d mice's hematocrit was about 50% lower than that of controls (p<0.05) and their performance level was about 25% lower (p<0.001). A total of 1583 genes exhibited significant changes in their expression levels. However, 68 genes were strongly up-regulated (normalized ratio>1.4) and 115 were strongly down-regulated (normalized ratio<0.80). The transcriptome data mining analysis showed that the exercise in the EPO-d mice induced muscle hypoxia, oxidative stress and proteolysis associated with energy pathway disruptions in glycolysis and mitochondrial oxidative phosphorylation.

CONCLUSIONS

Our results showed that the lack of functional EPO induced a decrease in the aerobic exercise capacity. This decrease was correlated with the hematocrit and reflecting poor oxygen supply to the muscles. The observed alterations in the muscle transcriptome suggest that physiological concentrations of EPO exert both direct and indirect muscle-protecting effects during exercise. However, the signaling pathway involved in these protective effects remains to be described in detail.

Identification of hypertrophy- and heart failure-associated genes by combining in vitro and in vivo models

Heart failure (HF) is a complex disease involving multiple changes including cardiomyocyte hypertrophy (growth). Here we performed a set of screens in different HF and hypertrophy models to identify differentially expressed genes associated with HF and/or hypertrophy. Hypertensive Ren2 rats and animals with postmyocardial infarction (post-MI) HF were used as in vivo HF models, and neonatal rat cardiomyocytes treated with hypertrophy inducing hormones phenylephrine, endothelin-1, and isoproterenol were used as in vitro models. This combined approach revealed a robust set of genes that were differentially expressed both in vitro and in vivo. This included known genes like NPPA (ANP) and FHL1, but also novel genes not previously associated with hypertrophy/HF. Among these are PTGIS, AKIP1, and Dhrs7c, which could constitute interesting targets for further investigations. We also identified a number of in vivo specific genes and these appeared to be enriched for fibrosis, wounding, and stress responses. Therefore a number of novel genes within this in vivo specific list could be related to fibroblasts or other noncardiomyocytes present in the heart. We also observed strong differences between the two HF rat models. For example KCNE1 was strongly upregulated in Ren2, but not in post-MI HF rats, suggesting possible etiology-specific differences. Moreover, Gene Ontology analysis revealed that genes involved in fatty acid oxidation were specifically down regulated in the post-MI group only. Together these results show that combining multiple models, both in vivo and in vitro, can provide a robust set of hypertrophy/HF-associated genes. Moreover it provides insight in the differences between the different etiology models and neurohormonal effects.

Erythropoietin protects against doxorubicin-induced heart failure

The hormone erythropoietin (EPO) has been demonstrated to have cardioprotective properties. The present study investigates the role of EPO to prevent heart failure following cancer treatment with doxorubicin [adriamycin (AD)]. Male Wistar rats (150 ± 10 g) were treated with saline (vehicle control group); with EPO, subcutaneously at 1,000 IU/kg body wt, three times per week for 4 wk (EPO group); with adriamycin, intraperitoneally at 2.5 mg/kg body wt, three times per week for 2 wk (AD group); and with adriamycin and EPO (EPO-AD group). Echocardiographic measurements showed that EPO-AD treatment prevented the AD-induced decline in cardiac function. Each of the hearts was then exposed to ischemia and reperfusion during Langendorff perfusion. The percentage of recovery after ischemia-reperfusion was significantly greater in EPO-AD than the AD-treated group for left ventricular developed pressure, maximal increase in pressure, and rate pressure product. The level of oxidative stress was significantly higher in AD (5 μM for 24 h)-exposed isolated cardiomyocytes; EPO (5 U/ml for 48 h) treatment prevented this. EPO treatment also decreased AD-induced cardiomyocyte apoptosis, which was associated with the decrease in the Bax-to-Bcl2 ratio and caspase-3 activation. Immunostaining of myocardial tissue for CD31 showed a significant decrease in the number of capillaries in AD-treated animals. EPO-AD treatment restored the number of capillaries. In conclusion, EPO treatment effectively prevented AD-induced heart failure. The protective effect of EPO was associated with a decreased level of oxidative stress and apoptosis in cardiomyocytes as well as improved myocardial angiogenesis.

Erythropoietin in the intensive care unit: beyond treatment of anemia

Erythropoietin (EPO) is the major hormone stimulating the production and differentiation of red blood cells. EPO is used widely for treating anemia of critical illness or anemia induced by chemotherapy. EPO at pharmacological doses is used in this setting to raise hemoglobin levels (by preventing the apoptosis of erythroid progenitor cells) and is designed to reduce patient exposure to allogenic blood through transfusions. Stroke, heart failure, and acute kidney injury are a frequently encountered clinical problem. Unfortunately, in the intensive care unit advances in supportive interventions have done little to reduce the high mortality associated with these conditions. Tissue protection with EPO at high, nonpharmacological doses after injury has been found in the brain, heart, and kidney of several animal models. It is now well known that EPO has anti-apoptotic effects in cells other than erythroid progenitor cells, which is considered to be independent of EPOs erythropoietic activities. This review article summarizes what is known in preclinical models of critical illness and discusses why this does not correlate with randomized, controlled clinical trials.

The impairment of ILK related angiogenesis involved in cardiac maladaptation after infarction

Background

Integrin linked kinase (ILK), as an important component of mechanical stretch sensor, can initiate cellular signaling response in the heart when cardiac preload increases. Previous work demonstrated increased ILK expression could induce angiogenesis to improved heart function after MI. However the patholo-physiological role of ILK in cardiac remodeling after MI is not clear.

Method and Results

Hearts were induced to cardiac remodeling by infarction and studied in Sprague-Dawley rats. Until 4 weeks after infarction, ILK expression was increased in non-ischemic tissue in parallel with myocytes hypertrophy and compensatory cardiac function. 8 weeks later, when decompensation of heart function occurred, ILK level returned to baseline. Followed ILK alternation, vascular endothelial growth factor (VEGF) expression and phosphorylation of endothelial nitric oxide synthase (eNOS) was significantly decreased 8 weeks after MI. Histology study also showed significantly microvessel decreased and myocytes loss 8 weeks paralleled with ILK down-regualtion. While ILK expression was maintained by gene delivery, tissue angiogenesis and cardiac function was preserved during cardiac remodeling.

Conclusion

Temporally up-regulation of ILK level in non-ischemic myocytes by increased external load is associated with beneficial angiogenesis to maintain infarction-induced cardiac hypertrophy. When ILK expression returns to normal, this cardiac adaptive response for infarction is weaken. Understanding the ILK related mechanism of cardiac maladaptation leads to a new strategy for treatment of heart failure after infarction.

A pilot study of chronic, low-dose epoetin-{beta} following percutaneous coronary intervention suggests safety, feasibility, and efficacy in patients with symptomatic ischaemic heart failure

AIMS

Low-dose epoetin-β improved neo-angiogenesis and cardiac regeneration in experimental models of ischaemic cardiomyopathy without raising haemoglobin. No clinical study has tested this approach to date.

METHODS AND RESULTS

We performed a randomized, placebo-controlled, double-blind, single-centre study of 35 IU/kg body weight epoetin-β given subcutaneously once weekly for 6 months started within 3 weeks after successful percutaneous coronary intervention (PCI). Patients were included if they presented with a lesion within the proximal segment of the left anterior descending artery, the right coronary artery, or circumflex and had symptomatic heart failure. Patients with ST-segment elevation due to an acute myocardial infarct were excluded. The outcome variables were measured at baseline and at 6 months. Primary outcome measure was individual change in ejection fraction; secondary outcome was safety, change in N-terminal pro-brain natriuretic peptide, and peak VO(2). Twenty-four patients completed the 6-month treatment course. No adverse event related to the treatment occurred. Low-dose epoetin-β following PCI significantly improved global ejection fraction as measured by echocardiography (EPO: ΔEF 5.2 ± 2.0%, P= 0.013; placebo: ΔEF 0.3 ± 1.6%, P= 0.851; P= 0.019 for the inter-group difference) and cardiac magnetic resonance (EPO: ΔEF 3.1 ± 1.6%, P= 0.124; placebo: -1.9 ± 1.2%, P= 0.167; P= 0.042 for the inter-group difference). N-terminal pro-brain natriuretic peptide levels decreased in both groups without significant inter-group differences. Peak VO(2) levels increased significantly by 3.9 ± 1.1% (P< 0.05) in the EPO group, whereas in the placebo group the increase did not reach statistical significance (Δpeak VO(2) 3.0 ± 1.6, P = ns). No significant difference regarding peak VO(2) was observed between the EPO and placebo groups.

CONCLUSIONS

Low-dose epoetin-β treatment following PCI is safe and feasible, and has possible beneficial effects on global ejection fraction and measures of exercise capacity. Extended low-dose epoetin-β treatment warrants further mechanistic studies as well as larger clinical trials.

CLINICAL TRIAL REGISTRATION INFORMATION

NCT00568542.

Cytokine combination therapy with erythropoietin and granulocyte colony stimulating factor in a porcine model of acute myocardial infarction

Purpose

Erythropoietin (EPO) and granulocyte colony stimulating factor (GCSF) have generated interest as novel therapies after myocardial infarction (MI), but the effect of combination therapy has not been studied in the large animal model. We investigated the impact of prolonged combination therapy with EPO and GCSF on cardiac function, infarct size, and vascular density after MI in a porcine model.

Methods

MI was induced in pigs by a 90 min balloon occlusion of the left anterior descending coronary artery. 16 animals were treated with EPO+GCSF, or saline (control group). Cardiac function was assessed by echocardiography and pressure-volume measurements at baseline, 1 and 6 weeks post-MI. Histopathology was performed 6 weeks post-MI.

Results

At week 6, EPO+GCSF therapy stabilized left ventricular ejection fraction, (41 ± 1% vs. 33 ± 1%, p < 0.01) and improved diastolic function compared to the control group. Histopathology revealed increased areas of viable myocardium and vascular density in the EPO+GCSF therapy, compared to the control. Despite these encouraging results, in a historical analysis comparing combination therapy with monotherapy with EPO or GCSF, there were no significant additive benefits in the LVEF and volumes overtime using the combination therapy.

Conclusion

Our findings indicate that EPO+GCSF combination therapy promotes stabilization of cardiac function after acute MI. However, combination therapy does not seem to be superior to monotherapy with either EPO or GCSF.

Acute coronary syndromes: the unfulfilled promise of erythropoietin in patients with MI

Over the past 5–10 years, the positive effects of erythropoietin on myocardial infarction have been reported in several experimental, animal models. However, the results of the REVEAL study call into question the beneficial effects of erythropoietin in humans presenting with myocardial infarction.

Aging, telomeres and heart failure

During normal aging, the heart undergoes functional, morphological and cellular changes. Although aging per se does not lead to the expression of heart failure, it is likely that age-associated changes lower the threshold for the manifestation of signs and symptoms of heart failure. In patients, the susceptibility, age of onset and pace of progression of heart failure are highly variable. The presence of conventional risk factors cannot completely explain this variability. Accumulation of DNA damage and telomere attrition results in an increase in cellular senescence and apoptosis, resulting in a decrease in the number and function of cells, contributing to the overall tissue and organ dysfunction. Biological aging, characterized by reduced telomere length, provides an explanation for the highly interindividual variable threshold to express the clinical syndrome of heart failure at some stage during life. In this review, we will elaborate on the current knowledge of aging of the heart, telomere biology and its potential role in the development of heart failure.

Anemia and iron deficiency in heart failure: mechanisms and therapeutic approaches

Anemia and iron deficiency are common in patients with heart failure (HF), and are associated with worse symptoms and adverse outcomes in this population. Although the two can occur together, anemia in HF is often not caused by iron deficiency, and iron deficiency can be present without causing anemia. Erythropoiesis-stimulating agents have been investigated extensively in the past few years and might be of benefit in patients with HF and anemia. However, concerns have arisen regarding the safety of erythropoiesis-stimulating agents in patients with chronic kidney disease and so the results of a large mortality trial are eagerly awaited to provide information on safety in patients with HF. Iron supplementation or replacement is a much older treatment option for patients with HF and anemia, but questions about the safety of intravenous iron, and absorption problems with oral formulations have prevented its widespread use to date. In the past few years, however, new data on the importance of iron deficiency in HF have become available, and a number of studies with intravenous iron have shown promising results. Therefore, this treatment approach is likely to become an attractive option for patients with HF and iron deficiency, both with and without anemia.

Erythropoietin receptor signaling mitigates renal dysfunction-associated heart failure by mechanisms unrelated to relief of anemia

OBJECTIVES

We examined the effect of asialoerythropoietin (asialoEPO), a nonerythrogenic derivative of erythropoietin (EPO), on renal dysfunction-associated heart failure.

BACKGROUND

Although EPO is known to exert beneficial effects on cardiac function, the clinical benefits in patients with chronic kidney disease are controversial. It remains to be addressed whether previously reported outcomes were the result of relief of the anemia, adverse effects of EPO, or direct cardiovascular effects.

METHODS

Mice underwent 5/6 nephrectomy to cause renal dysfunction. Eight weeks later, when renal dysfunction was established, anemia and cardiac dysfunction and remodeling were apparent. Mice were then assigned to receive saline (control), recombinant human erythropoietin (rhEPO) at 5,000 IU (714 pmol)/kg, or asialoEPO at 714 pmol/kg, twice/week for 4 weeks.

RESULTS

Although only rhEPO relieved the nephrectomy-induced anemia, both rhEPO and asialoEPO significantly and similarly mitigated left ventricular dilation and dysfunction. The hearts of rhEPO- or asialoEPO-treated mice showed less hypertrophy, reflecting decreases in cardiomyocyte hypertrophy and degenerative subcellular changes, as well as significant attenuation of fibrosis, leukocyte infiltration, and oxidative deoxyribonucleic acid damage. These phenotypes were accompanied by restored expression of GATA-4, sarcomeric proteins, and vascular endothelial growth factor and decreased inflammatory cytokines and lipid peroxidation. Finally, myocardial activation was observed of extracellular signal-regulated protein kinase and signal transducer and activator of transcription pathways in the treated mice.

CONCLUSIONS

EPO receptor signaling exerts direct cardioprotection in an animal model of renal dysfunction-associated heart failure, probably by mitigating degenerative, pro-fibrosis, inflammatory, and oxidative processes but not through relief of anemia.

Erythropoietin and the heart: facts and perspectives

EPO (erythropoietin) has long been identified as a primary regulator of erythropoiesis. Subsequently, EPO has been recognized as playing a role in a broad variety of processes in cardiovascular pathophysiology. In particular, the tight interactions of EPO with the nitric oxide pathway, apoptosis, ischaemia, cell proliferation and platelet activation appear of great interest. Although enhanced EPO synthesis is viewed as an appropriate compensatory mechanism in the cardio-renal syndrome, which features CHF (congestive heart failure) and CRF (chronic renal failure), maladaptative excessive EPO synthesis in the advanced stages of these diseases appears to be predictive of higher mortality. Clinical trials based on the use of EPO in both heart and renal failure have so far produced contradictory results, whereas treatment targeted to restore low Hb levels appears rational and is supported by regulatory authorities. New areas for therapeutic use of EPO, such as acute coronary syndromes, are under investigation, and they are discussed in the present review together with other clinical applications in cardiovascular diseases. The revisited concept of a potential use of endogenous EPO levels as a predictor of CHF severity, as well as in the monitoring of responses to treatment, deserves appropriate investigation, as this may identify EPO as a useful biomarker in the clinical management of cardiovascular diseases.

Design and rationale of the Reduction of Infarct Expansion and Ventricular Remodeling with Erythropoietin after Large Myocardial Infarction (REVEAL) trial

BACKGROUND

Acute myocardial infarction (MI) remains a leading cause of death despite advances in pharmacologic and percutaneous therapies. Animal models of ischemia/reperfusion have demonstrated that single-dose erythropoietin may reduce infarct size, decrease apoptosis, and increase neovascularization, possibly through mobilization of endothelial progenitor cells.

STUDY DESIGN

REVEAL is a randomized, double-blind, placebo-controlled, multicenter trial evaluating the effects of epoetin α on infarct size and left ventricular remodeling in patients with large MIs. The trial comprises a dose-escalation safety phase and a single-dose efficacy phase using the highest acceptable epoetin α dose up to 60,000 IU. Up to 250 ST-segment elevation myocardial infarction patients undergoing primary or rescue percutaneous coronary intervention will be randomized to intravenous epoetin α or placebo within 4 hours of successful reperfusion. The primary study end point is infarct size expressed as a percentage of left ventricular mass, as measured by cardiac magnetic resonance imaging 2 to 6 days post study medication administration. Secondary end points will assess changes in endothelial progenitor cell numbers and changes in indices of ventricular remodeling.

CONCLUSION

The REVEAL trial will evaluate the safety and efficacy of the highest tolerated single dose of epoetin α in patients who have undergone successful rescue or primary percutaneous coronary intervention for acute ST-segment elevation myocardial infarction.

Erythropoiesis-stimulating agents and heart failure

Anemia is a common comorbidity in heart failure (HF) patients. Its occurrence and severity are associated with worse prognosis. Although the etiology of anemia is multifactorial, inappropriate erythropoietin (EPO) production and/or bone-marrow resistance to EPO appear crucial in majority of anemic HF patients. Consequently, treatment based on this pathophysiological background may prove to be most effective and beneficial. In a number of smaller clinical studies, administration of erythropoiesis-stimulating agents (ESAs) to anemic HF patients improved a number of surrogate endpoints, including left ventricular function, exercise capacity, renal function, and different quality of life parameters. However, two larger, phase II studies, did not fully confirm these promising results. Furthermore, many concerns have been raised on the safety of ESAs after the recent publication of studies correcting anemia in patients with chronic kidney disease (CKD). On the other hand, chronic HF population varies significantly from CKD patients, with different comorbidities, renal function, and etiology of anemia. Moreover, ESAs have been shown to possess robust nonhematopoietic effects in the heart, namely inhibition of apoptosis and stimulation of neovascularization. Therefore, large-scale trials with ESAs are required to examine the effect and safety of anemia treatment in HF patients.

Cellular basis of uraemic cardiomyopathy: a role for erythropoietin?

The use of erythropoietin (EPO) has revolutionized the treatment of anaemia associated with many conditions including chronic kidney disease (CKD). However, little is known of the cellular impact of EPO on the uraemic heart. The discovery that the EPO receptor (EPOR) is also expressed on non-haematopoietic cells including cardiomyocytes highlights a role of EPO beyond haematopoiesis. Animal models of heart failure have shown EPO can potentially reverse cardiac remodelling and improve myocardial function. Damage to the kidney, during uraemia, results in a decreased EPO production, which may render the uraemic heart more susceptible to damage and heart failure. Here we review current data on the cellular actions of EPO in models of left ventricular hypertrophy and heart failure and highlight parallels with the uraemic heart.

A single dose of erythropoietin in ST-elevation myocardial infarction

AIMS

Cardioprotective effects of erythropoietin (EPO) have been shown in experimental and smaller clinical studies. We performed a prospective, multicentre, randomized trial to assess the effects of a single high dose of EPO after primary coronary intervention (PCI) for an ST-elevation myocardial infarction (STEMI). Methods and results Patients with a successful PCI for a first STEMI were randomized to receive either standard medical care alone, or in combination with a single bolus with 60,000 IU i.v. of epoetin alfa within 3 h after PCI. Primary endpoint was left ventricular ejection fraction (LVEF) after 6 weeks, assessed by planar radionuclide ventriculography. Pre-specified secondary endpoints included enzymatic infarct size and major adverse cardiovascular events. A total of 529 patients were enrolled (EPO n = 263, control n = 266). At baseline (before EPO administration), groups were well-matched for all relevant characteristics. After a mean of 6.5 (± 2.0) weeks, LVEF was 0.53 (± 0.10) in the EPO group and 0.52 (± 0.11) in the control group (P = 0.41). Median area under the curve (inter-quartile range) after 72 h for creatinine kinase was 50 136 (28 212-76 664)U/L per 72 h in the EPO group and 53 510 (33 973-90 486)U/L per 72 h in the control group (P = 0.058). More major adverse cardiac events occurred in the control than in the EPO group (19 vs. 8; P = 0.032). Conclusion A single high dose of EPO after a successful PCI for a STEMI did not improve LVEF after 6 weeks. However, the use of EPO was related to less major adverse cardiovascular events and a favourable clinical safety profile.

CLINICAL TRIAL REGISTRATION INFORMATION

NCT00449488; http://www.clinicaltrials.gov/ct2/show/NCT00449488?term=voors&rank=2.

Erythropoiesis stimulation in acute ischemic syndromes

Erythropoietin (EPO) is a hematopoietic hormone with extensive nonhematopoietic properties. The discovery of an EPO receptor outside the hematopoietic system has fuelled research into the beneficial effects of EPO for various conditions, predominantly in cardiovascular disease. Experimental evidence has revealed the cytoprotective properties of EPO, and it seems that the EPO-EPO receptor system provides a powerful backbone against acute myocardial ischemia, gaining from the different properties of EPO. There is an ongoing discussion about possible discrepancy between preclinical and clinical effects of EPO on the cardiovascular system. Large, randomized, placebo-controlled clinical trials are underway to give a final verdict on EPO treatment for acute coronary syndromes.

Cardioprotective effects of erythropoietin on postresuscitation myocardial dysfunction in appropriate therapeutic windows

OBJECTIVE

Erythropoietin has been noted for its cardioprotective effects. The objective of the study is to investigate its effects on postresuscitation myocardial dysfunction and therapeutic windows.

DESIGN

Randomized animal study.

SETTING

Animal research laboratory.

SUBJECTS

Adult male adult Wistar rats.

INTERVENTIONS

Cardiopulmonary resuscitation was started after 6.5 or 9.5 mins of asphyxia-induced cardiac arrest. The resuscitated animals received either erythropoietin (1000, 3000, or 5000 U/kg) or placebo intravenously 3 mins after return of spontaneous circulation.

MEASUREMENTS AND MAIN RESULTS

Erythropoietin treatment improved the 3-day survival and left ventricular dP/dt40 and peak negative dP/dt after 6.5 mins asphyxia-induced cardiac arrest. The cardioprotective effects of erythropoietin decreased after 9.5 mins asphyxia-induced cardiac arrest with worse postresuscitation left ventricular dP/dt40 and peak negative dP/dt (p < .01 for both). The erythropoietin showed a dose-dependent response for its cardioprotective effects. The 3-day survival rates were higher in the group treated with erythropoietin 5000 U/kg than with 3000 and 1000 U/kg groups (p = .045 and .003, respectively). Postresuscitation left ventricular dP/dt40 and peak negative dP/dt were more preserved in the group treated with erythropoietin 5000 U/kg than the groups with lower doses (p < .05 for both).

CONCLUSIONS

Erythropoietin has the potential to improve postresuscitation myocardial dysfunction and short-term survival in appropriate therapeutic windows.

Anemia correction by erythropoietin reduces BNP levels, hospitalization rate, and NYHA class in patients with cardio-renal anemia syndrome

Little is known about the effect of anemia correction with erythropoietin (EPO) on B-type natriuretic peptide (BNP) levels, NYHA class, and hospitalization rate. The aim of the study was to investigate, in patients with cardio-renal anemia syndrome, the effects of EPO on hemochrome and renal function parameters and BNP levels. We also analyzed the effect of EPO therapy on hospitalization rate and NYHA class after 12 months in comparison with a population undergoing to standard therapy. We performed a randomized double-blind controlled study of correction of the anemia with subcutaneous α (group A n = 13) or β (group B n = 14) EPO for 12 months in addition to standard therapy with oral iron in 27 subjects. Control group (n = 25 patients) received only oral iron. Significant increase in hemoglobin (Hb), hematocrit (Hct), and red blood cells (RBC) were revealed in EPO groups at 12 months; Hb, group A 12.3 ± 0.6; group B 11.7 ± 0.8; control group 10.6 ± 0.5 g/dl P < 0.0001; Hct group A 34.2 ± 2.3, group B 34 ± 2, control group 32.3 ± 1.8% P < 0.01; RBC, group A 3.9 ± 0.2, group B 3.8 ± 0.2, control group 3.3 ± 0.2, (P < 0.0001). Plasma BNP levels in EPO groups were significantly reduced after 12 months (group A: 335 ± 138 vs. group B: 449 ± 274 pg/ml control group 582 ± 209 pg/ml (P < 0.01). After 12 months of treatment, hospitalization rate and NYHA class were reduced in EPO groups with respect to control group (P < 0.05). Finally, an inverse correlation was observed between BNP and Hb levels in EPO Groups (r = -0.70 P < 0.001). EPO treatment reduces BNP levels and hospitalization rate in patients with cardio-renal anemia syndrome. The correction of anemia by EPO treatment appears able to improve clinical outcome in this subset of patients with heart failure.

High cumulative incidence of cancer in patients with cardio-renal-anaemia syndrome

AIMS

The combination of chronic kidney disease (CKD), chronic heart failure (HF), and anaemia, the so-called cardio-renal-anaemia syndrome (CRA) is associated with dysregulation of erythropoietin levels and inflammation. Both have been associated with the development of cancer. This study aimed to determine the cumulative incidence of cancer in patients with CRA, as compared with anaemic CKD and control patients.

METHODS AND RESULTS

Patients aged <80 years who attended the nephrology or cardiology outpatient clinics between March 2006 and November 2007 were eligible for inclusion in this retrospective case-control study if haemoglobin <8.1 mmol/L (13 g/dL) and serum creatinine >80 mmol/L (0.90 mg/dL). Medical records dating back to 1996 were reviewed. The relationship between cancer and CRA, chronic HF, CKD, and anaemia was analysed using logistic regression analysis. Data from 1087 patients were reviewed. We identified 348 patients with both CKD and anaemia, of whom 132(38.3%) had CRA. The control group included 264 patients attending the hypertension outpatient clinic. Patients with CRA had a 19% cumulative incidence of cancer compared with 11% for patients with anaemia, CKD and no chronic HF, and 11% in the control group. The odds ratio (OR) for cancer was 1.8(95% CI 1.0-3.2) for the CRA group compared with the control group. Chronic HF was an independent risk factor for cancer after correction for age and gender (adjusted OR 2.0; 95% CI 1.2-3.3, P = 0.007).

CONCLUSION

The cumulative incidence of cancer among patients with CRA is high compared with controls and to anaemic CKD patients without chronic HF. Chronic HF was an independent risk factor for cancer. These results stress the importance of clarifying the mechanisms involved in the development of cancer in CRA.

Cytokine combination therapy with long-acting erythropoietin and granulocyte colony stimulating factor improves cardiac function but is not superior than monotherapy in a mouse model of acute myocardial infarction

BACKGROUND

Erythropoietin (EPO) and granulocyte colony stimulating factor (GCSF) are potential novel therapies after myocardial infarction (MI). We first established the optimal and clinically applicable dosages of these drugs in mobilizing hematopoietic stem cells (HSC), and then tested the efficacy of monotherapy and combination therapy post-MI.

METHODS AND RESULTS

Optimal doses were established in enhanced green fluorescent protein (eGFP) + chimeric mice (n = 30). Next, mice underwent MI and randomized into 4 groups (n = 18/group): 1) GCSF; 2) EPO; 3) EPO+GCSF; and 4) control. Left ventricular (LV) function was analyzed pre-MI, at 4 hours and at 28 days post-MI. Histological assessment of infarct size, blood vessels, apoptotic cardiomyocytes, and engraftment of eGFP+ mobilized cells were analyzed at day 28. LV function in the control group continued to deteriorate, whereas all treatments showed stabilization. The treatment groups resulted in less scarring, increased numbers of mobilized cells to the infarct border zone (BZ), and a reduction in the number of apoptotic cardiomyocytes. Both EPO groups had significantly more capillaries and arterioles at the BZ.

CONCLUSION

We have established the optimal doses for EPO and GCSF in mobilizing HSC from the bone marrow and demonstrated that therapy with these agents, either as monotherapy or combination therapy, led to improvement of cardiac function post-MI. Combination therapy does not seem to have additive benefit over monotherapy in this model.

Prolonged therapy with erythropoietin is safe and prevents deterioration of left ventricular systolic function in a porcine model of myocardial infarction

BACKGROUND

Erythropoietin (EPO) has generated interest as a novel therapy after myocardial infarction (MI), but the safety and efficacy of prolonged therapy have not been studied in a large animal model of reperfused MI.

METHODS AND RESULTS

MI was induced in pigs by a 90-minute balloon occlusion of the left anterior descending coronary artery. Sixteen animals were randomized to either EPO or saline (control group). Inflammatory markers, bone marrow cell mobilization, and left ventricular function (by both echocardiography and pressure-volume measurements) were assessed at baseline, 1 and 6 weeks post-MI. EPO therapy was associated with a significant increase in hemoglobin and mononuclear counts. D-dimer and C-reactive protein levels did not differ between groups. At week 6, EPO therapy prevented further deterioration of left ventricular ejection fraction (39 +/- 2% vs. 33 +/- 1%, P < .01) and improved wall motion score index (P < .02). Histopathology revealed increased areas of viable myocardium, vascular density, and capillary-to-myocyte ratio in the EPO therapy compared with the control (all P < .05).

CONCLUSION

Prolonged EPO therapy after MI in a large animal model is safe and leads to an increase in viable myocardium, increased vascular density, and prevents further deterioration of left ventricular function. These results support future clinical studies in post-MI patients.

Is there a role for erythropoietin in cardiovascular disease?

IMPORTANCE OF THE FIELD

Despite the advances in the cardiovascular field, cardiovascular diseases remain an important health problem with a high mortality rate. Novel therapeutic attempts that target myocardial ischemia and heart failure offer attractive adjuncts and/or alternatives to commonly employed regimens. The development of novel laboratory technologies over the last decade has led to substantial progress in bringing new therapies to the bedside.

AREAS COVERED IN THIS REVIEW

Current experimental and clinical trials in the use of erythropoietin (EPO) in cardiovascular diseases are reviewed.

WHAT THE READER WILL GAIN

This review will widen knowledge of the therapeutic potential of EPO's non-erythropoietic beneficial effects in a clinical cardiovascular setting.

TAKE HOME MESSAGE

Results from preclinical trials regarding the non-erythropoietic effects of erythropoietin are really encouraging. Further clinical studies are warranted to define the beneficial role of EPO in the clinical setting of coronary artery disease, heart failure and peripheral artery disease.

The protective effect of erythropoietin on the acute phase of corrosive esophageal burns in a rat model

INTRODUCTION

An experimental study was conducted to investigate the effects of erythropoietin on the acute phase of esophageal burn damage induced by sodium hydroxide.

MATERIALS AND METHODS

A standard esophageal alkaline burn was produced by the application of 10% sodium hydroxide to the distal esophagus in an in vivo rat model. Fifty-six female rats were allocated into three groups: Group BC (baseline control, n = 8) rats were uninjured and untreated, Group PC (positive control, n = 24) rats were injured but untreated and Group EPO (erythropoietin-treated, n = 24) rats were injured and given subcutaneous erythropoietin (1,000 IU/kg per day), 15 min, 24, and 48 h after administration of the NaOH solution. Six animals from Group PC and six from Group EPO were killed at 4, 24, 48, and 72 h after application of NaOH to the esophagus. All of animals in Group BC were killed 4 h after exposure to 0.9% NaCl. Oxidative damage was assessed by measuring levels of malondialdehyde (MDA) and nitric oxide (NO), and activities of superoxide dismutase (SOD) and catalase (CAT) in homogenized samples of esophageal tissue. Histologic damage to esophageal tissue was scored by a single pathologist blind to groups.

RESULTS

MDA levels in the BC and EPO groups were significantly lower than those in the PC group (p < 0.05). CAT and SOD activities, and NO levels in the BC and EPO groups were significantly higher than in the PC group (p < 0.05). Esophageal tissue damage measured at 4, 24, 48, and 72 h after NaOH application was significantly less in the EPO group than in the PC group (p < 0.05).

CONCLUSIONS

When administered early after an esophageal burn induced by 10% sodium hydroxide in this rat model, erythropoietin significantly attenuated oxidative damage, as measured by biochemical markers and histologic scoring.

Endogenous Erythropoietin and Outcome in Heart Failure

Background— Endogenous erythropoietin is increased in patients with heart failure (HF). Previous small-scale data suggest that these erythropoietin levels are related to prognosis. This study aims to analyze the clinical and prognostic value of erythropoietin levels in relation to hemoglobin in a large cohort of HF patients.

Methods and Results— In patients hospitalized for HF, endogenous erythropoietin levels were measured at discharge and after 6 months. In anemic patients, the relation between erythropoietin and hemoglobin levels was determined by calculating the observed/predicted ratio of erythropoietin levels. We studied data from 605 patients with HF. Mean age was 71±11 years; 62% were male; and mean left ventricular ejection fraction was 0.33±0.14. Median erythropoietin levels were 9.6 U/L at baseline and 10.5 U/L at 6 months. Higher erythropoietin levels at baseline were independently related to an increased mortality at 18 months (hazard ratio, 2.06; 95% confidence interval, 1.40 to 3.04; P <0.01). In addition, persistently elevated erythropoietin levels (higher than median at baseline and at 6 months) were related to an increased mortality risk (hazard ratio, 2.24; 95% confidence interval, 1.02 to 4.90; P =0.044). The observed/predicted ratio was determined in a subset of anemic patients, 79% of whom had erythropoietin levels lower than expected and 9% had levels higher than expected on the basis of their hemoglobin. Multivariate Cox regression analysis revealed that a higher observed/predicted ratio was related to an increased mortality risk (hazard ratio, 3.52; 95% confidence interval, 1.53 to 8.12; P =0.003).

Conclusions— Erythropoietin levels predict mortality in HF patients, and persistently elevated levels have an independent prognostic value. In anemic HF patients, the majority had a low observed/predicted ratio. However, a higher observed/predicted ratio may be related to an independent increased mortality risk.