Low-dose Erythropoietin Research Articles

Low and sustained doses of erythropoietin prevent preterm infants from intraventricular hemorrhage

In addition to its hematopoietic function, erythropoietin (EPO) has demonstrated neuroprotective properties in preclinical studies, particularly in cases of reduced oxygenation or ischemia in the neonatal brain. While these findings have sparked optimism for its potential clinical application, the efficacy of EPO remains contentious in translational assays. Notably, while repeated administration of low doses of EPO has correlated with a decrease in adverse outcomes, the use of high EPO doses has shown either negligible or potentially detrimental effects on the incidence of brain injury. In this pilot study, we explored the effects of low and sustained doses of EPO (400 IU/kg) on the incidence of intraventricular hemorrhage (IVH) in premature infants. EPO was administered intravenously three times a week until the infants reached 32 weeks corrected gestational age. Our results indicate a significant decrease in the incidence of IVH with EPO treatment. Although, this study does not provide conclusive evidence on EPO's ability to reverse established IVH, these results strongly support the need for larger-scale clinical trials to further assess EPO's therapeutic potential.

#460 Digital twin in hemodialysis model, with machine learning algorithms. Data from the Andalusian Hemodialysis Registry. SICATA

Abstract Background and Aims Orthodoxly, a digital twin is a computer simulation of an individual, “in silico”, and in real time. A digital twin can also be created with BIG DATA. The Objective It is the development of a survival digital twin model using Machine Learning algorithms using data from the Andalusian SICATA registry. Method The database was composed of 29,189 records at the time of analysis and contains variables in the areas of comorbidity, anemia, efficacy of renal replacement therapy (RRT), and renal bone disease. The algorithms used were: - XG Boost, AdaBoost, Cat boost. KNN, Random Forest, Decision Trees, Logistic Regression. A survival model was developed with each Machine Learning (ML) algorithm . The metrics of the models were taken into account: precision, calibration, accuracy. The software used was Orange based on Python and Rattle based on R. An explanation of the “black box” type models was carried out using SHAP (Shapley values) based on game theory. Results The characteristics that the digital twin that we have modeled with the greatest survival would have are: 1. Age equal to or less than 45 years, 2. Being included in the kidney transplant waiting list. 3. Longer duration of the hemodialysis session. 4. Low doses of Erythropoietin. 5. Normal or high serum albumin levels. 6. BMI > 21.The sample was stratified according to the Ultrafiltration (UF) ratio during the Hemodialysis session in ml/kg/hour. Group1: UF <4 ml/kg/hour. Group2: UF 5-9 ml/kg/hour. Group3: UF>9 ml/kg/hour. And a mortality study was carried out using multivariate Logistic Regression. We found that the OR for mortality in groups 2 and 3 was 17% and 24% in relation to group 1, which had the lowest mortality. Conclusion ML has revealed that the UF ratio (ml/kg/hour) is an important predictor variable of mortality. In our studio a UF ratio<4 ml/kg/hour is safe ML has found an answer to a question that we had not asked ourselves when beginning the study: What is the optimal UF rate in the hemodialysis session?

Abstract 2771: Increased mtDNA copy number via EPOR signaling: A potential mechanism for metastatic dissemination in head and neck squamous cell carcinoma

Abstract Introduction: Head and Neck Squamous cell carcinoma (HNSCC) is characterized by high degree of invasion, locoregional metastasis, relapse which leads to overall poor prognosis. The molecular mechanism responsible for aggressiveness is poorly understood. A better understanding of molecular pathways involved shall precede the identification of newer diagnostic tools and therapeutic targets. We explored EPOR signaling pathway in Circulating tumor cells (CTCs) and HNSCC cell lines. Methods and Results: By using a validated in-house CTC isolation protocol, which addresses various drawbacks of currently available techniques and isolates CTCs suitable for various downstream molecular analysis, we isolated CTCs from HNSCC patients. The whole transcriptome analysis was performed from CTCs using ultra-low cell number RNA sequencing and corresponding primary tumors in 24 paired samples. We found a significant transcriptomic heterogeneity in CTCs, which are associated with overall disease outcome in HNSCC patients. To explore the plausible molecular pathways, we also identified 521 differentially expressed genes in CTCs with respect to primary tumors and various canonical pathways including oxidative phosphorylation, TCA cycle, cytokine-cytokine receptor interaction signaling, and ECM receptor interaction were enriched in CTC samples. Overexpression of erythropoietin receptor (EPOR) along with various genes encoded by mitochondrial genome and genes involved in maintenance of mtDNA in CTCs as compared to primary tumors was an important finding from our data. When analyzed in depth, there was a significant positive correlation between various genes involved in mtDNA maintenance (ABAT, NT5M) and encoded by mitochondrial genome (MT-ND1, MT-ND2, MT-ND4, MT-ND5, MT-ND6, MT-CO1, MT-CO2, MT-ATP6, MT-CYTB) with EPOR expression in our RNA seq data which is also substantiated by analyzing TCGA data. We confirmed these findings experimentally in HNSCC cell lines Cal 27 and FaDu. It was also observed that metastatic cell line FaDu has significantly higher mtDNA content as compared to non-metastatic cell line Cal 27, which was correlated with EPOR expression. Treatment with low dose Erythropoietin (0.1IU/mL) which a natural ligand for EPOR, enhanced mtDNA content in both the cell lines at low doses and boosted the metastatic capability while minimal effect on cell proliferation was observed. Conclusion: EPOR signaling might promote the metastatic ability of cancer cells and may act as a potential target for cancer dissemination and metastasis. Citation Format: Anshika Chauhan, Geeta S. Boora, Sahana Ghosh, Subrata K. Patra, Roshan K. Verma, Jaimanti Bakshi, Debajyoti Chatterjee, Radhika Srinivasan, Sushmita Ghoshal, Arindam Maitra, Arnab Pal. Increased mtDNA copy number via EPOR signaling: A potential mechanism for metastatic dissemination in head and neck squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2771.

Erythropoiesis-related RNAs biomarkers are sensitive and specific to low-dose erythropoietin treatment at sea level and altitude

Background: Indirect detection of recombinant human erythropoietin (rhEPO) abuse in Anti-Doping world is done by hematological module of athlete biological passport (ABP). However, actual markers (reticulocytes (%RET) and hemoglobin (HGB)) of this module are not enough specific and have difficulties to distinguish recombinant human erythropoietin (rhEPO) administration from altitude sojourn especially if both condition are merged. Previous study have demonstrated that erythropoiesis-related RNAs, genes 5’-aminolevulinate synthase 2 ( ALAS2) and carbonic anhydrase 1 ( CA1) in capillary dried blood spots (DBS) could be potential biomarkers to increased specificity and sensitivity of the ABP in case of hypoxic conditions. Study design and methods: In the present study, we monitored ALAS2 and CA1 expression in DBS after injection of 20 IU kg bw-1 epoetin alpha at sea level and the effect merged with altitude exposure. For this purpose, DBSs samples collected from 39 volunteers’ males and females were analyzed. Participants were divided in two groups (EPO and placebo) and subjects from both groups sojourned at sea level and at altitude. The purpose was to evaluate the performance of RNAs biomarkers for the detection of rHEPO injection in a longitudinal blinded setting. Results: Our results illustrated a clear significant increase of ALAS2 until to 300% when treated at sea level and at altitude. Regarding CA1 the increase is up to 200% in both conditions. Interestingly, our results suggested no combined effect of altitude and rhEPO injection on ALAS2 and CA1 biomarkers as previously demonstrated with %RET values. In placebo group. Moreover, no effect of altitude on ALAS2 and CA1 was observed in contrast to %RET parameter. Results from blind setting test demonstrated a performance of interpretation of 92% regarding ALAS2 and CA1 monitoring. Conclusion: Erythropoiesis-related RNAs in capillary DBS such as ALAS2 and CA1 were sensitive and specific biomarkers for low-dose rhEPO misuse at sea level and altitude. Interestingly, altitude seemed not to be a confounding factors for ALAS2 and CA1 biomarkers in contrast to %RET. Furthermore, this investigation provide evidence that low-dose of rhEPO injections can be detected in a longitudinal blinded setting with RNA biomarkers in DBS. World Anti-Doping Agency (WADA) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Erythropoietin inhibits ferroptosis and ameliorates neurological function after spinal cord injury.

Ferroptosis is one of the critical pathological events in spinal cord injury. Erythropoietin has been reported to improve the recovery of spinal cord injury. However, whether ferroptosis is involved in the neuroprotective effects of erythropoietin on spinal cord injury has not been examined. In this study, we established rat models of spinal cord injury by modified Allen's method and intraperitoneally administered 1000 and 5000 IU/kg erythropoietin once a week for 2 successive weeks. Both low and high doses of erythropoietin promoted recovery of hindlimb function, and the high dose of erythropoietin led to better outcome. High dose of erythropoietin exhibited a stronger suppressive effect on ferroptosis relative to the low dose of erythropoietin. The effects of erythropoietin on inhibiting ferroptosis-related protein expression and restoring mitochondrial morphology were similar to those of Fer-1 (a ferroptosis suppressor), and the effects of erythropoietin were largely diminished by RSL3 (ferroptosis activator). In vitro experiments showed that erythropoietin inhibited RSL3-induced ferroptosis in PC12 cells and increased the expression of xCT and Gpx4. This suggests that xCT and Gpx4 are involved in the neuroprotective effects of erythropoietin on spinal cord injury. Our findings reveal the underlying anti-ferroptosis role of erythropoietin and provide a potential therapeutic strategy for treating spinal cord injury.

Erythropoietin Receptor (EPOR) Signaling in the Osteoclast Lineage Contributes to EPO-Induced Bone Loss in Mice.

Erythropoietin (EPO) is a pleiotropic cytokine that classically drives erythropoiesis but can also induce bone loss by decreasing bone formation and increasing resorption. Deletion of the EPO receptor (EPOR) on osteoblasts or B cells partially mitigates the skeletal effects of EPO, thereby implicating a contribution by EPOR on other cell lineages. This study was designed to define the role of monocyte EPOR in EPO-mediated bone loss, by using two mouse lines with conditional deletion of EPOR in the monocytic lineage. Low-dose EPO attenuated the reduction in bone volume (BV/TV) in Cx3cr1Cre EPORf/f female mice (27.05%) compared to controls (39.26%), but the difference was not statistically significant. To validate these findings, we increased the EPO dose in LysMCre model mice, a model more commonly used to target preosteoclasts. There was a significant reduction in both the increase in the proportion of bone marrow preosteoclasts (CD115+) observed following high-dose EPO administration and the resulting bone loss in LysMCre EPORf/f female mice (44.46% reduction in BV/TV) as compared to controls (77.28%), without interference with the erythropoietic activity. Our data suggest that EPOR in the monocytic lineage is at least partially responsible for driving the effect of EPO on bone mass.

Erythroid lineage Jak2V617F expression promotes atherosclerosis through erythrophagocytosis and macrophage ferroptosis.

Elevated hematocrit is associated with cardiovascular risk; however, the causality and mechanisms are unclear. The JAK2V617F (Jak2VF) mutation increases cardiovascular risk in myeloproliferative disorders and in clonal hematopoiesis. Jak2VF mice with elevated WBCs, platelets, and RBCs display accelerated atherosclerosis and macrophage erythrophagocytosis. To investigate whether selective erythroid Jak2VF expression promotes atherosclerosis, we developed hyperlipidemic erythropoietin receptor Cre mice that express Jak2VF in the erythroid lineage (VFEpoR mice). VFEpoR mice without elevated blood cell counts showed increased atherosclerotic plaque necrosis, erythrophagocytosis, and ferroptosis. Selective induction of erythrocytosis with low-dose erythropoietin further exacerbated atherosclerosis with prominent ferroptosis, lipid peroxidation, and endothelial damage. VFEpoR RBCs had reduced antioxidant defenses and increased lipid hydroperoxides. Phagocytosis of human or murine WT or JAK2VF RBCs by WT macrophages induced ferroptosis, which was prevented by the ferroptosis inhibitor liproxstatin-1. Liproxstatin-1 reversed increased atherosclerosis, lipid peroxidation, ferroptosis, and endothelial damage in VFEpoR mice and in Jak2VF chimeric mice simulating clonal hematopoiesis, but had no impact in controls. Erythroid lineage Jak2VF expression led to qualitative and quantitative defects in RBCs that exacerbated atherosclerosis. Phagocytosis of RBCs by plaque macrophages promoted ferroptosis, suggesting a therapeutic target for reducing RBC-mediated cardiovascular risk.

Mechanism of erythropoietin-induced M2 microglia polarization via Akt / Mtor / P70S6k signaling pathway in the treatment of brain injury in premature mice and its effect on biofilm

ABSTRACT We investigated the mechanism of erythropoietin (EPO) in brain injury in premature mice based on Akt/mTOR/p70S6K signaling pathway. The brain injury model group of premature mice was obtained by intraperitoneal injection of lipopolysaccharide during pregnancy. Normal mice were taken as the control group. The model mice were divided into low-dose EPO (1,000 IU/kg, L-EPO), medium-dose EPO (2,500 IU/kg, M-EPO), and high-dose EPO groups (5,000 IU/kg, H-EPO) by intraperitoneal injection. The levels of malondialdehyde (MDA) and total superoxide dismutase (T-SOD) were detected. TUNEL staining and Western blotting were used to detect the differences in neuronal apoptosis index (AI), microglial polarization marker protein, and Akt/mTOR/p70S6K-related protein expression levels in each group. Compared with the control group, the protein levels of AI, MDA, Bax, and iNOS in the model, L-EPO, and M-EPO groups were significantly increased, while the T-SOD level and Bcl-2, ARG1, p-Akt, p-mTOR, and p-70S6K protein levels were significantly decreased (P < 0.05). Compared with the model group, AI, MAD levels and Bax, iNOS protein expression levels in L-EPO, M-EPO, and H-EPO groups were significantly decreased, while T-SOD level and Bcl-2, ARG1, p-Akt, p-mTOR, and p-70S6K protein levels were significantly increased. The changes were dose-dependent. In summary, EPO can activate microglia transformation from M1 to M2 through Akt/mTOR/p70S6K signaling pathway.

Change in Hemoglobin with Androgen and Low Dose Erythropoietin Versus Erythropoietin Alone in Patients of Anemia of Chronic Kidney Disease

Objectives: To determine the mean rise in hemoglobin with androgen and low dose erythropoietin versus erythropoietin alone in patients of anemia of chronic kidney disease. Methodology: A randomized control trial was conducted at a tertiary care hospital between October 2019 to April 2020. Both male and female from age &gt;17years to 70 years with anemia of CKD as per operational definition were included. Patients with a history of blood transfusion in the last three months. Patients already on Erythropoietin therapy or those with uncontrolled hypertension BP &gt;190/105 mm Hg at the time of study were excluded. Relevant data including demographic details, baseline hemoglobin was noted. Patients were randomly assigned to group A or group B by lottery method. Patients in group A were given 100mg of androgen (Nandrolone Decanoate) intramuscularly once weekly plus low dose of erythropoietin (2000 units twice weekly) subcutaneously for 6 months and patients in group B were given standard dose of erythropoietin (4000 units twice weekly) subcutaneously for 6 months. Rise in hemoglobin was recorded as per operational definition. Follow up was ensured by taking telephone contact. Data was recorded on pre-designed proforma. Results: Mean Hb levels after treatment were calculated as 12.48+1.20 in Group-A and 11.12+1.32 in Group-B, p value was calculated as 0.0001 showing a significant difference between the two groups, comparison of mean increase in Hb levels after treatment were calculated as 3.0+0.09 in Group-A and 1.72+0.67 in Group-B, p value was calculated as 0.0001 showing a significant difference between the two groups. Conclusion: We concluded that there was significantly greater rise in the mean hemoglobin with androgen plus low dose erythropoietin as compared to erythropoietin alone in treatment of anemia of chronic kidney disease. Nevertheless, further large-scale and multi-center studies will be needed to further explore the long-term efficacy and adverse effects of androgens among patients of anemia of chronic kidney disease. Keywords: Chronic kidney disease, anemia, androgen and low dose erythropoietin versus erythropoietin alone, mean increase

Abstract 14224: JAK2V617F Red Blood Cells Promote Atherosclerosis and Thrombosis

Elevated hematocrit is associated with cardiovascular risk; however, the causality and mechanisms are unclear. The JAK2V617F (JAK2VF) mutation markedly increases cardiovascular risk both in myeloproliferative disorders with elevated blood cell counts and in the much more prevalent clonal hematopoiesis of indeterminate potential with normal blood cell counts. Jak2VF mouse models with elevated white blood cells (WBC), platelets and red blood cells (RBCs) display accelerated atherosclerosis. However, whether Jak2VF RBCs promote atherogenesis and thrombosis independently from increased WBC and platelets remains uncertain. We used Erythropoietin Receptor (EpoR) Cre recombinase to generate a conditional knock-in of murine Jak2VF (VFEpoR) in the RBC lineage. Hyperlipidemic VFEpoR mice without elevated blood cell counts showed accelerated arterial thrombosis and increased atherosclerotic plaque necrosis. Induction of erythrocytosis with low dose erythropoietin (EPO) without concomitant leukocytosis or thrombocytosis further worsened thrombosis and atherosclerosis. VFEpoR atherosclerotic lesions featured endothelial barrier breakdown, RBC infiltration, iron deposition, lipid peroxidation, macrophage erythrophagocytosis and macrophage ferroptosis. VFEpoR RBCs had reduced antioxidant defenses and contained increased ROS and lipid hydroperoxides. Phagocytosis of murine or human WT or Jak2 VF RBCs by WT macrophages induced lipid peroxidation and ferroptotic death that was prevented by the ferroptosis inhibitor Liproxstatin-1. Ferroptosis inhibition reversed increased atherosclerosis and necrotic core formation in VFEpoR mice but had no impact in controls. These studies demonstrate that both qualitative and quantitative defects in Jak2VF RBCs accelerate atherosclerosis and thrombosis. Phagocytosis of WT or Jak2VF RBCs by macrophages leads to ferroptotic cell death, suggesting ferroptosis as a new therapeutic target to reduce RBC-mediated cardiovascular risk.

Erythropoietin inhibits apoptosis of retinal ganglion cells induced by high glucose through JNK signaling pathway

The aim of this study was to investigate the effect of erythropoietin (EPO) on the apoptosis of retinal ganglion cells (RGCs) induced by high glucose and its mechanism. Rat primary RGCs were extracted to establish high glucose-induced apoptosis models using a 30 mM high-glucose medium. Then flow cytometry, cell counting kit-8 (CCK-8) assay and Western blotting assay were performed to detect the effects of high-, medium- and low-dose EPO on the apoptosis of RGCs induced by high glucose. Next, the molecular mechanism by which EPO suppressed the high glucose-induced apoptosis of RGCs was explored via gene array assay and bioinformatics analysis. The results and mechanism of bioinformatics analysis were verified by Western blotting assay. Finally, the small interfering ribonucleic acid (siRNA) experiment was applied to knock down tyrosine-protein phosphatase non-receptor type 1 (PTPN1) and PTPN11 to verify their roles in the inhibition of EPO on the apoptosis of RGCs triggered by high glucose. Flow cytometry-Annexin V/propidium iodide (PI) staining and CCK-8 assay confirmed that the high-, medium- and low-dose EPO inhibited the apoptosis of RGCs induced by high glucose in a dose-dependent manner (P<0.05). Subsequently, Western blotting assay results manifested that the high-, medium- and low-dose EPO reduced the expression levels of apoptosis-related proteins active-cysteinyl aspartate specific proteinase 3 (Caspase 3) and active- Caspase 9 in a dose-dependent manner (P<0.05). Moreover, according to gene array assay and bioinformatics analysis results, the c-Jun N-terminal kinase (JNK) signaling pathway, PTPN1 and PTPN11 might exert crucial effects in the inhibition of EPO on the apoptosis of RGCs induced by high glucose. Western blotting assay results also demonstrated that, compared with the high-glucose treatment, the high-dose EPO treatment decreased the protein expression level of phosphorylated (p)-JNK1/JNK but increased the protein expression levels of PTPN1 and PTPN11 (P<0.05). Moreover, flow cytometry-Annexin V/PI staining and CCK-8 assay results revealed that in EPO-treated cells, knocking down PTPN1 and PTPN11 significantly reversed the protective effect of EPO against high glucose-induced retinal ganglion cell apoptosis (P<0.05). Lastly, Western blotting assay illustrated that knocking down PTPN1 and PTPN11 significantly abolished the inhibition of high-dose EPO on the JNK signaling pathway. EPO may suppress the JNK signaling pathway by raising the expression levels of PTPN1 and PTPN11, so as to inhibit the apoptosis of RGCs triggered by high glucose.

Systemic low-dose erythropoietin administration improves the vascularization of collagen-glycosaminoglycan matrices seeded with adipose tissue-derived microvascular fragments

Adipose tissue-derived microvascular fragments (MVF) are used as vascularization units in tissue engineering. In this study, we investigated whether the vascularization capacity of MVF can be improved by systemic low-dose erythropoietin (EPO) administration. MVF were isolated from the epididymal fat of donor mice and seeded onto collagen-glycosaminoglycan matrices, which were implanted into full-thickness skin defects within dorsal skinfold chambers of recipient mice. Both donor and recipient mice were treated daily with either EPO (500 IU/kg) or vehicle (0.9% NaCl). The implants were analyzed by stereomicroscopy, intravital fluorescence microscopy, histology, and immunohistochemistry. EPO-treated MVF contained a comparable number of proliferating Ki67+ but less apoptotic cleaved caspase-3+ endothelial cells when compared to vehicle-treated controls. Moreover, EPO treatment accelerated and improved the in vivo vascularization, blood vessel maturation, and epithelialization of MVF-seeded matrices. These findings indicate that systemic low-dose EPO treatment is suitable to enhance the viability and network-forming capacity of MVF.

Erythropoietin-Induced Autophagy Protects Against Spinal Cord Injury and Improves Neurological Function via the Extracellular-Regulated Protein Kinase Signaling Pathway.

The objective of this study was to explore the neuroprotective molecular mechanisms of erythropoietin (EPO) in rats following spinal cord injury (SCI). First, a standard SCI model was established. After drug or saline treatment was administered, locomotor function was evaluated in rats using the Basso, Beattie, and Bresnahan (BBB) locomotor rating scale. H&E, Nissl, and TUNEL staining were performed to assess the ratio of cavities, number of motor neurons, and apoptotic cells in the damaged area. The relative protein and mRNA expressions were examined using western blot and qRT-PCR analyses, and the inflammatory markers, axon special protein, and neuromuscular junctions (NMJs) were detected by immunofluorescence. Both doses of EPO notably improved locomotor function, but high-dose EPO was more effective than low-dose EPO. Moreover, EPO reduced the cavity ratio, cell apoptosis, and motor neuron loss in the damaged area, but enhanced the autophagy level and extracellular-regulated protein kinase (ERK) activity. Treatment with an ERK inhibitor significantly prevented the effect of EPO on SCI, and an activator mimicked the benefits of EPO. Further investigation revealed that EPO promoted SCI-induced autophagy via the ERK signaling pathway. EPO activates autophagy to promote locomotor function recovery in rats with SCI via the ERK signaling pathway.

ERFE regulation in sickle cell disease: complex but promising.

ERFE regulation in sickle cell disease: complex but promising.

P713Short term treatment of a low dose erythropoietin improves vascular function in a rat model of insulin resistance

Abstract Background/Introduction Erythropoietin (EPO) exerts haematopoiesis-independent cardiovascular and renal protective effects by binding to EPO receptors expressed in hearts, arteries, and kidneys. We have reported that EPO inhibits vascular and renal injury in rat models of hypertension and type 1 diabetes. Recent studies report that EPO improves glucose tolerance in insulin resistant animals. Purpose This study investigated whether EPO would inhibit vascular and renal dysfunction in the setting of insulin resistance. Methods Rats were treated with sucrose (12% in drinking water) for 10 weeks to induce insulin resistance. EPO (3 times/week, s.c) was administered at the dose of 150U/kg for 10 weeks from the beginning (group A) or at the dose of 75U/kg for the last 4 weeks (group B) of sucrose treatment. Blood pressure was measured every second week by the tail-cuff method. HOMA-IR, haematocrit, and urinary protein excretion were measured. Using isolated aortas, acetylcholine-induced vasorelaxation under phenylephrine-induced pre-contraction was examined. Aortic sections were stained with haematoxylin-eosin. Results Both groups A and B showed higher haematocrit levels compared with the control and sucrose alone-treated groups. Sucrose treatment increased HOMA-IR (7.7±2.0 vs. 24±4.5, p&lt;0.05), which was attenuated in groups A (3.6±0.9) and B (9.7±4.0). EPO treatment (150U/kg) had no effects on blood pressure for the first 4 weeks but caused time-dependent increases in blood pressure from the 6th week. Increased proteinuria and impaired aortic vasorelaxation in sucrose-treated rats were exacerbated by EPO (150U/kg) maybe because of hypertension (Control 122±2mmHg, Sucrose 125±2mmHg, group A 148±5mmHg), one of the major side effects of EPO. According to these results, we treated a half dose of EPO only for the last 4 weeks (group B). A lower dose of EPO treatment for a shorter period did not increase proteinuria (Control 15±2mg/day, Sucrose 25±3mg/day, group B 24±3mg/day) despite a mild increase in blood pressure (132±2mmHg). Impaired endothelium-dependent vasodilation and aortic thickening in the aorta of sucrose alone-treated rats were attenuated by lower and shorter EPO treatment (group B). Conclusions EPO inhibited insulin resistance and vascular injury in sucrose-induced insulin resistant rats. Further investigation into the mechanisms of tissue protective effects of EPO, especially focusing on the effects on insulin signalling in not only hepatic and muscle cell but also vascular and renal cells, will be needed.

Long-term pre- and postconditioning with low doses of erythropoietin protects critically perfused musculocutaneous tissue from necrosis

It has been shown that pre- and postconditioning of ischemically challenged tissue with erythropoietin (EPO) is able to reduce necrosis in a dose-dependent manner. The aim of this study was to determine the tissue-protective effects of different EPO dosages and administration regimes. Three groups of six C57Bl/6-mice each were analyzed: (1) pre- and postconditioning with initial high doses of EPO (starting at 2500 I.U./kg bw i.p.) followed by low doses of EPO (125 I.U./kg bw i.p.) (EPO-high-dose); (2) pre- and postconditioning with low doses of EPO (125 I.U./kg bw i.p.) (EPO-low-dose); and (3) untreated control group. Randomly perfused musculocutaneous flaps were mounted on dorsal skinfold chambers undergoing acute persistent ischemia and developing ∼50% necrosis without treatment. Intravital epifluorescence microscopy was performed at days 1, 3, 5, 7, and 10 after surgery, assessing flap necrosis, microcirculation, and angiogenesis. The hematocrit was measured at days 0, 3, 7, and 10. Only the EPO-low-dose regimen was associated with a significant reduction of necrosis when compared to untreated controls. EPO-low-dose showed a higher increase in both arteriolar diameter and velocity, thereby resulting in a significantly increased arteriolar blood flow and a hence higher functional capillary density (FCD) of the critically perfused zone. EPO-induced angiogenesis was significantly increased in EPO-low-dose at days 7 and 10. Only EPO-high-dose reached a significant hematocrit increase by day 10. Tissue pre- and postconditioning with low doses of EPO protects the critically perfused musculocutaneous tissue by maintaining capillary perfusion because of increased arteriolar blood flow mediated by nitric oxide (NO) expression.

Differential Effects of Low-Dose Erythropoietin in Rat Model of Diabetic Nephropathy

Background. Previous reports on the renoprotective effect of erythropoietin (EPO) in the setting of chronic kidney disease (CKD) have yielded conflicting results. The aim of this study is to clarify the effect of low, non-hematopoietic dose of EPO on the evolution of diabetic nephropathy (DN) in rat model. Methods. Low dose of recombinant human EPO (150 U/kg, s.c. three times/week) was given to streptozotocin (STZ)-induced diabetic rats in two schedules; in the first one, EPO was given from day 2 after STZ injection till the end of the study (28 weeks) as prophylactic treatment; and in the other schedule EPO was given after development of DN (last 8 weeks) as therapeutic treatment. Albuminuria, blood pressure, creatinine clearance, renal venous oxygen tension (vPO2), plasma EPO, hematocrit and renal histopathology were assessed. Results. Unexpectedly, 28 weeks administration of EPO to diabetic rats led to aggravation of albuminuria and worsening of histopathological damage in spite of partial correction of renal hypoxia. Contrary to this, terminal 8 weeks EPO therapy of DN reduced albuminuria and demonstrated some favorable effects on biochemical changes and histologic picture. Conclusion. Low dose EPO exerted differential effects in rat model of DN according to treatment duration. In addition, findings of the present study warrants further investigations of the exact renoprotective role of EPO in diabetic patients with CKD who receive EPO therapy for long periods.

Faim2 contributes to neuroprotection by erythropoietin in transient brain ischemia.

Delayed cell death in the penumbra region of acute ischemic stroke occurs through apoptotic mechanisms, making it amenable to therapeutic interventions. Fas/CD95 mediates apoptotic cell death in response to external stimuli. In mature neurons, Fas/CD95 signaling is modulated by Fas-apoptotic inhibitory molecule 2 (Faim2), which reduces cell death in animal models of stroke, meningitis, and Parkinson disease. Erythropoietin (EPO) has been studied as a therapeutic strategy in ischemic stroke. Erythropoietin stimulates the phosphatidylinositol-3 kinase/Akt (PI3K/Akt) pathway, which regulates Faim2 expression. Therefore, up-regulation of Faim2 may contribute to neuroprotection by EPO. Male Faim2-deficient mice (Faim2-/- ) and wild-type littermates (WT) were subjected to 30min of middle cerebral artery occlusion (MCAo) followed by 72h of reperfusion. EPO was applied before (30min) and after (24 and 48h) MCAo. In WT mice application of EPO at a low dose (5000U/kg) significantly reduced stroke volume, whereas treatment with high dose (90000U/kg) did not. In Faim2-/- animals administration of low-dose EPO did not result in a significant reduction in stroke volume. Faim2 expression as measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR) increased after low-dose EPO but not with high dose. An extensive phenotyping including analysis of cerebral vessel architecture did not reveal confounding differences between the genotypes. In human post-mortem brain Faim2 displayed a differential expression in areas of penumbral ischemia. Faim2 up-regulation may contribute to the neuroprotective effects of low-dose erythropoietin in transient brain ischemia. The dose-dependency may explain mixed effects of erythropoietin observed in clinical stroke trials.

Low-Dose Erythropoietin in Patients With ST-Segment Elevation Myocardial Infarction (EPO-AMI-II) - A Randomized Controlled Clinical Trial.

Erythropoietin (EPO) has antiapoptotic and tissue-protective effects, but previous clinical studies using high-dose EPO have not shown cardioprotective effects, probably because of platelet activation and a lack of knowledge regarding the optimal dose. In contrast, a small pilot study using low-dose EPO has shown improvement in left ventricular function without adverse cardiovascular events.Methods and Results:We performed a multicenter (25 hospitals), prospective, randomized, double-blind, placebo-controlled, dose-finding study to clarify the efficacy and safety of low-dose EPO in patients with ST-segment elevation myocardial infarction (STEMI) under the Evaluation System of Investigational Medical Care of the Ministry of Health, Labor and Welfare of Japan. In total, 198 STEMI patients with low left ventricular ejection fraction (LVEF <50%) were randomly assigned to receive intravenous administration of EPO (6,000 or 12,000 IU) or placebo within 6 h of successful percutaneous coronary intervention. At 6 months, there was no significant dose-response relationship in LVEF improvement among the 3 groups tested (EPO 12,000 IU: 5.4±9.3%, EPO 6,000 IU: 7.3±7.7%, Placebo: 8.1±8.3%, P=0.862). Low-dose EPO also did not improve cardiac function, as evaluated by 99 mTc-MIBI SPECT or NT-proBNP at 6 months and did not increase adverse events. Administration of low-dose EPO did not improve LVEF at 6 months in STEMI patients (UMIN000005721).

EPOR2/βcR2-independendent effects of low-dose epoetin-α in porcine liver transplantation.

Ischemia–reperfusion injury (IRI) remains a key component of graft damage during transplantation. Erythropoietin (EPO) induces anti-inflammatory and anti-apoptotic effects via the EPOR2/βcR2 complex, with a potential risk of thrombosis. Previous work indicates that EPO has EPOR2/βcR2-independent protective effects via direct effects on the endothelium. As the EPOR2/βcR2 receptor has a very low affinity for EPO, we aimed to test the hypothesis that EPO doses below the level that stimulate this receptor elicit cytoprotective effects via endothelial stimulation in a porcine liver transplantation model. Landrace pigs underwent allogenic liver transplantation (follow-up: 6 h) with a portojugular shunt. Animals were divided into two groups: donor and recipient treatment with low-dose EPO (65 IU/kg) or vehicle, administered 6 h before cold perfusion and 30 min after warm reperfusion. Fourteen of 17 animals (82.4%) fulfilled the inclusion criteria. No differences were noted in operative values between the groups including hemoglobin, cold or warm ischemic time. EPO-treated animals showed a significantly lower histopathology score, reduced apoptosis, oxidative stress, and most important a significant up-regulation of endothelial nitric oxide (NO) synthase (eNOS). Donor and recipient treatment with low-dose EPO reduces the hepatic IRI via EPOR2/βcR2-independent cytoprotective mechanisms and represents a clinically applicable way to reduce IRI.