EPO-treated Animals Research Articles

The effects of IGF-1 and erythropoietin on apoptosis and telomerase activity in necrotizing enterocolitis model.

Apoptosis that occurs after hypoxia/reoxygenation (H/R) has an important role in the pathogenesis of necrotizing enterocolitis (NEC). Telomerase activity, showing the regeneration capacity, may also be important in the recovery process. Therefore, we aimed to investigate the effects of insulin-like growth factor-1 (IGF-1) and erythropoietin (EPO) on apoptosis and telomerase activity in an H/R model. Young mice were divided into four groups each containing ten Balb/c mice. Group 1 (H/R) were exposed to H/R; group 2 and group 3 were pretreated with IGF-1 and EPO, respectively, for 7 days before H/R. Group 4 served as control. Intestinal injury was evaluated by histological scoring and assessment of apoptosis was performed by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) test. Proapoptotic and antiapoptotic gene expressions and telomerase activity were analyzed by real-time PCR. IGF-1- and EPO-treated animals had decreased histological damage and apoptosis, confirmed by TUNEL test and caspase activity. Telomerase activity was increased in these animals in addition to increased expression of antiapoptotic genes. However, proapoptotic gene expressions were not statistically different. The protective effects of IGF-1 and EPO in H/R damage may be through increased expression of antiapoptotic genes and increased telomerase activity, especially for IGF-1. This is a comprehensive study measuring various variables, namely IGF-1, EPO, apoptosis, apoptotic and antiapoptotic genes, and telomerase activity in the NEC model. The intestinal protective effects of IGF-1 and EPO in H/R damage may occur through increased expression of antiapoptotic genes and increased telomerase activity. To the best of our knowledge, telomerase activity has not been investigated in the NEC model before. Regarding our results, novel strategies may be implemented for the early definitive diagnosis, robust preventive measures, and effective treatment modalities for NEC.

Erythropoietin does not improve fracture healing in aged mice.

Fracture healing in the elderly is associated with a declined healing potential caused by multiple factors including a delay of vascularization. Erythropoietin (EPO) has been demonstrated to improve vascularization and fracture healing in adult mice. We, therefore, hypothesized that EPO in aged mice also improves fracture healing. For this purpose, EPO was given daily in a femoral fracture model in aged mice and compared to vehicle-treated controls using radiological, biomechanical, histomorphometric and Western blot techniques. Blood analyses revealed significantly higher concentrations of hemoglobin and a higher hematocrit in EPO-treated animals at 14 and 35 days after fracture. Micro-computed tomography (μCT) indicated that the fraction of bone volume/tissue volume within the callus did not differ between the two groups. However, μCT showed a 3-fold increased tissue mineral density (TMD) in the callus of EPO-treated animals compared to controls. The callus TMD of the EPO-treated animals was also 2-fold higher when compared to the TMD of the unfractured contralateral femur. Interestingly, biomechanical analyses revealed a reduced bending stiffness in femurs of EPO-treated animals at day 35. The histomorphometrically analyzed callus size and callus composition did not show significant differences between the study groups. However, Western blot analyses exhibited an increased expression of osteoprotegerin (OPG), but in particular of receptor activator of NF-κB ligand (RANKL) in the callus of the EPO-treated animals. Further histological analyses of the callus tissue showed that this was associated with an increased number of newly formed blood vessels and a higher number of tartrate-resistant acid phosphatase (TRAP)+ cells. Conclusion: In fracture healing of aged mice EPO treatment increases callus TMD as well as OPG and RANKL expression, indicating an accelerated bone turnover when compared to controls. However, EPO does not improve fracture healing in aged mice. The process of fracture healing may be altered by EPO due to a deterioration of the microcirculation caused by the worsened rheological properties of the blood and due to an increased bone fragility caused by the accelerated bone turnover. Thus, EPO may not be used to improve fracture healing in the elderly.

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.

Erythropoietin is Neuroprotective During Ongoing Compression and Speeds Recovery Following Surgical Decompression in a Murine Model of Chronic Compression Neuropathy: N/A - Not a clinical study

Grant received from: American Foundation for Surgery of the Hand (Hand Surgeon Scientist Award), National Institute of Health grant (# 1 K08 AR060164-01A), Clinical and Translational Science Award (CTSA) grant (# UL1 TR000042), through the University of Rochester School of Medicine & Dentistry, University of Rochester CTSA award (# TL1 TR000096) from the National Center for Advancing Translational Sciences of the National Institutes of Health, University of Rochester Center Goldstein Grant, University of Rochester Laboratory Startup Fund, ART/CTSI Student Research Fellowship Award- salary support for Co-Investigator and medical student, Leigh Sundem There is no financial information to disclose. We previously described erythropoietin’s (EPO) effectiveness in ameliorating the effects of acute peripheral nerve crush. Pilot studies indicate that EPO therapy is an effective neuromodulatory agent for the treatment of chronic nerve compression (CNC) when used as an adjuvant to surgical decompression. This left open the question as to whether pretreatment with EPO during compression would be relevant in reducing the effect of ongoing compression. CNC injury was created in wild-type mice by placing an inert silastic sleeve around the sciatic nerve as in previous work. Decompression surgery was performed at 6 weeks with alternative mice receiving pre-decompressive treatment. Nerve conduction studies were performed weekly before decompression and every 48-hours thereafter until full recovery. Sixty mice were randomized into either a sham-surgery group, saline-treatment control (saline/saline), or 1 of 2 EPO-treatment groups with initiation of EPO at day 0 (EPO/EPO), or week 6 (saline/EPO) in conjunction with surgical decompression. Comparison of NCV was tested with one-way ANOVA followed by Student’s t-test in this dataset, which was normally distributed. During compression, there was a progressive decline in nerve conduction velocity (NCV) as compared to sham-injured animals where NCV remained normal (∼55 m/s) throughout the experiment (Figure 1A). NCV in saline-treated animals progressively decreased from normal (55.153.42 m/s) to a plateau (35.680.72 m/s) over 6 weeks of compression. This expected decline was strikingly attenuated in randomly-selected animals treated with EPO (NCV decreased from 54.091.67 to 45.771.08 m/s, P < 0.01) so that EPO-treated animals fared significantly better than saline-treated counterparts (P < 0.01). Following decompression, all animals recovered to a normal baseline NCV by day 15 (P = 0.74); however, the improvement in NCV observed was markedly accelerated within the first week post-decompression in the EPO-treated groups, and not in saline-treated counterparts (P < 0.01). Animals treated with EPO during both phases fully recovered in half the time as those treated only after decompression (day 5 versus day 9 P < 0.05). •This study supports the possibility of EPO as a neuroprotective agent during CNC injury in rodents and may support adjuvant use during active compression.•Improvement in electrophysiologic parameters is observed with EPO treatment during compression and decompression phases.•EPO may accelerate the natural recovery of decompressed nerves and protect against ongoing injury through the same mechanism, which suggests translational relevance.View Large Image Figure ViewerDownload Hi-res image Download (PPT) This research was supported by a 2013 Hand Surgeon Scientist Award from the American Foundation for Surgery of the Hand.

Erythropoietin in the treatment of carbon monoxide neurotoxicity in rat

Erythropoietin (EPO) plays a critical role in the development of the nervous system. In this study, the effects of EPO in carbon monoxide (CO) neurotoxicity were examined. Rats were exposed to 3000 ppm CO for 1 h and then different doses of EPO were administrated intraperitoneally. After 24 h, glial fibrillary acidic protein (GFAP) levels in the serum were determined and water content of brain and the extravasation of a tracer (Evans blue) were measured. Brain lipid peroxidation, myeloperoxidase activity Myelin basic protein (MBP) and BAX/BcL2 protein relative expressions were determined. Cation exchange chromatography was used to evaluate MBP alterations. Seven days after exposure, pathological assessment was performed after Klüver–Barrera staining. EPO reduced malondialdehyde levels at all doses (2500, 5000 and 10,000 u/kg). Lower doses of EPO (625, 1250, 2500 u/kg) significantly decreased the elevated serum levels of GFAP. EPO could not reduce the water content of the edematous poisoned brains. However, at 5000 and 10,000 u/kg it protected the blood brain barrier against integrity loss as a result of CO. EPO could significantly decrease the MPO activity. CO-mediated oxidative stress caused chemical alterations in MBP and EPO could partially prevent these biochemical changes. Fewer vacuoles and demyelinated fibers were found in the EPO-treated animals. EPO (5000 u/kg) could restore the MBP density. CO increased brain BAX/Bcl-2 ratio 38.78%. EPO reduced it 38.86%. These results reveal that EPO could relatively prevent different pathways of neurotoxicity by CO poisoning and thus has the potential to be used as a novel approach to manage this poisoning.

Monitoring of Short-Term Erythropoietin Therapy in Rats with Acute Spinal Cord Injury Using Manganese-Enhanced Magnetic Resonance Imaging.

To evaluate the short-term outcome of erythropoietin (EPO) therapy in rats with spinal cord injury (SCI) using manganese-enhanced magnetic resonance imaging (MEMRI). Rats were divided in an EPO and a control group. Laminectomy at Th11 was performed, followed by SCI. MnCl2 was applied into the cisterna magna and functional recovery was examined after injury using BBB-scoring. Then, rats were euthanized and the spinal cord was extracted for MEMRI. Finally, histological analysis was performed and correlated with MEMRI. EPO-treated animals showed significantly better functional recovery (P = .008, r = .62) and higher mean signal-to-noise ratio (SNR) in MEMRI compared to controls for slices 10-13 (P = .017, R(2) = .31) at the level of the lesion epicenter. Functional recovery correlated significantly with higher SNR values, determined using the mean SNR between slices 10 and 13 (P = .047, R(2) = .36). In this region, histology revealed a significantly decreased number of microglia cells and apoptosis in EPO-treated animals. MEMRI successfully depicts the therapeutic effect of EPO in early SCI that leads to a significant recovery in rats, a significantly reduced immune response and significantly reduced number of apoptotic cells at the height of the lesion epicenter.

Erythropoietin protects the systolic function of neonatal hearts against ischaemia/reperfusion injury

The effect of erythropoietin (EPO) on neonatal hearts is not well understood. The current hypothesis is that EPO has protective effects against ischaemia-reperfusion when administered prior to ischaemia induction. Systolic and diastolic indices, as well as the Akt and extracellular-regulated kinase (Erk) signalling pathways, were studied in vivo using a neonatal pig heart model. Regional ischaemia was induced for 45 min by the ligation of the left anterior descending artery, followed by 90 min of reperfusion. The treatment groups consisted of: (i) untreated controls, (ii) treatment with EPO 3 min prior to ischaemia and (iii) treatment with EPO 24 h before ischaemia. Sophisticated myocardial contractility indices were assessed by pressure/volume loops of the left ventricle. The Akt and Erk pathways were evaluated via a western blot. Elastance was found to be higher in the group receiving EPO 3 min prior to ischaemia. In addition, preload recruitable stroke work was higher for both groups receiving EPO prior to ischaemia when compared with controls. The time constant of the isovolumic relaxation and end-diastolic pressure-volume relationship did not differ between the three groups after 90 min of reperfusion. Furthermore, EPO treatment enhanced phosphorylation of Akt, but not Erk, and EPO-treated animals showed lower levels of apoptosis-related proteins. EPO had a protective effect on neonatal systolic function after ischaemia/reperfusion injury, but no effect on diastolic function. This cardioprotective effect might be mediated by the activation of the Akt pathway.

Erythropoietin Attenuates Neurological and Histological Consequences of Toxic Demyelination in Mice

Erythropoietin (EPO) reduces symptoms of experimental autoimmune encephalomyelitis in rodents and shows neuroregenerative effects in chronic progressive multiple sclerosis. The mechanisms of action of EPO in these conditions with shared immunological etiology are still unclear. Therefore, we used a model of toxic demyelination allowing exclusion of T cell-mediated inflammation. In a double-blind (for food/injections), placebo-controlled, longitudinal four-arm design, 8-wk-old C57BL/6 mice (n = 26/group) were assigned to cuprizone-containing (0.2%) or regular food (ground chow) for 6 wks. After 3 wks, mice were injected every other day with placebo or EPO (5,000 IU/kg intraperitoneally) until the end of cuprizone feeding. Half of the mice were exposed to behavioral testing, magnetic resonance imaging (MRI) and histology immediately after treatment cessation, whereas the other half were allowed a 3-wk treatment-free recovery. Immediately after termination of cuprizone feeding, all toxin-exposed mice were compromised regarding vestibulomotor function/coordination, with EPO-treated animals performing better than placebo. Likewise, ventricular enlargement after cuprizone, as documented by MRI, was less pronounced upon EPO. After a 3-wk recovery, remarkable spontaneous improvement was observed in all mice with no measurable further benefit in the EPO group ("ceiling effect"). Histological analysis of the corpus callosum revealed attenuation by EPO of the cuprizone-induced increase in microglial numbers and amyloid precursor protein accumulations as a readout of inflammation and axonal degeneration. To conclude, EPO ameliorates neurological symptoms in the cuprizone model of demyelination, possibly by reduction of inflammation-associated axonal degeneration in white matter tracts. These findings underscore the value of future therapeutic strategies for multiple sclerosis based on EPO or EPO variants.

Effects of erythropoietin on electrocardiogram changes in carbon monoxide poisoning: an experimental study in rats.

The aim of this study was to define the electrocardiogram (ECG) changes following the moderate to severe CO intoxication in rats, and also evaluating the effect of erythropoietin (EPO) on observed cardiac disturbances. The growing literature on erythropoietin effect on cardiac ischemia led us to question its effect on cardiotoxicity due to the carbon monoxide poisoning. Wistar rats were exposed to three different concentrations of CO (250 PPM, 1000 PPM or 3000 PPM). EPO was administrated (5000 IU/Kg, intraperitoneal injection) at the end of CO exposure and then the animals were re-oxygenated with ambient air. Subsequently ECG recording, heart rate and carboxyhemoglobin values were evaluated. ECG changes following the CO intoxication included ST segment elevation and depression, T wave inversion and first-degree AV block. Ischemic ECG changes reduced significantly in EPO-treated animals. In the present study, for the first time, EPO was investigated for the management of cardiac complications due to the CO poisoning. Our results showed that EPO could inhibit ischemic changes of ECG after the CO poisoning.

Migration of bone marrow‐derived cells and improved perfusion after treatment with erythropoietin in a murine model of myocardial infarction

Erythropoietin (EPO) was shown to have protective effects after myocardial infarction (MI) by neovascularization and antiapoptotic mechanisms. Beside direct receptor-dependent mechanisms, mobilization and homing of bone marrow-derived cells (BMCs) may play a pivotal role in this regard. In this study, we intended to track different subpopulations of BMCs and to assess serially myocardial perfusion changes in EPO-treated mice after MI. To allow tracking of BMCs, we used a chimeric mouse model. Therefore, mice (C57BL/6J) were sublethally irradiated, and bone marrow (BM) from green fluorescent protein transgenic mice was transplanted. Ten weeks later coronary artery ligation was performed to induce MI. EPO was injected for 3 days with a total dose of 5000 IU/kg. Subpopulations (CD31, c-kit, CXCR-4 and Sca-1) of EGFP+ cells were studied in peripheral blood, bone marrow and hearts by flow cytometry. Myocardial perfusion was serially investigated in vivo by pinhole single-photon emission computed tomography (SPECT) at days 6 and 30 after MI. EPO-treated animals revealed an enhanced mobilization of BMCs into peripheral blood. The numbers of these cells in BM remained unchanged. Homing of all BMCs subpopulations to the ischaemic myocardium was significantly increased in EPO-treated mice. Among the investigated subpopulations, EPO predominantly affected migration of CXCR-4+ (4.3-fold increase). Repetitively SPECT analyses revealed a reduction of perfusion defects after EPO treatment over time. Our study shows that EPO treatment after MI enhances the migration capacity of BMCs into ischaemic tissue, which may attribute to an improved perfusion and reduced size of infarction, respectively.

Erythropoietin stimulates bone formation, cell proliferation, and angiogenesis in a femoral segmental defect model in mice

The glycoprotein erythropoietin (EPO) has been demonstrated to stimulate fracture healing. The aim of the present study was to investigate the effect of EPO treatment on bone repair in a femoral segmental defect model. Bone repair was analyzed in mice which were treated by EPO (500IE/kg/d intraperitoneally; n=38) and in mice which received the vehicle for control (n=40). Two and 10 weeks after creating a 1.8mm femoral segmental defect, bone repair was studied by micro-CT, histology, and Western blot analysis. At 10 weeks, micro-CT and histomorphometric analyses showed a significantly higher bridging rate of the bone defects in EPO-treated animals than in controls. This was associated by a significantly higher bone volume within the segmental defects of the EPO-treated animals. At 2 weeks, Western blot analyses revealed a significantly higher expression of vascular endothelial growth factor (VEGF) in EPO-treated animals compared to controls. Accordingly, the number of blood vessels was significantly increased in the EPO group at 2 weeks. At 10 weeks, we found a significantly higher expression of proliferating cell nuclear antigen (PCNA) in EPO-treated animals when compared to controls. Western blot analyses showed no significant differences between the groups in the expression of the endothelial and inducible nitric oxide synthases (eNOS and iNOS) and the angiopoietin receptor Tie-2. Immunohistochemistry confirmed the results of the Western blot analyses, demonstrating a significantly higher number of VEGF- and PCNA-positive cells in EPO-treated animals than in controls at 2 and 10 weeks, respectively. We conclude that EPO is capable of stimulating bone formation, cell proliferation and VEGF-mediated angiogenesis in a femoral segmental defect model.

Low dose erythropoietin stimulates bone healing in mice

Beyond its classical role in regulation of erythropoiesis, erythropoietin (EPO) has been shown to exert protective and regenerative actions in a variety of non-hematopoietic tissues. However, little is known about potential actions in bone regeneration. To analyze fracture healing in mice, a femoral 0.25 mm osteotomy gap was stabilized with a pin-clip technique. Animals were treated with 500 U EPO/kg bw per day or with vehicle only. After 2 and 5 weeks, fracture healing was analyzed biomechanically, radiologically and histologically. Expression of PCNA and NFκB was examined by Western blot analysis. Vascularization was analyzed by immunohistochemical staining of PECAM-1. Circulating endothelial progenitor cells were measured by flow-cytometry. Herein, we demonstrate that EPO-treatment significantly accelerates bone healing in mice. This is indicated by a significantly greater biomechanical stiffness and a higher radiological density of the periosteal callus at 2 and 5 weeks after fracture and stabilization. Histological analysis demonstrated significantly more bone and less cartilage and fibrous tissue in the periosteal callus. Endosteal vascularization was significantly increased in EPO-treated animals when compared to controls. The number of circulating endothelial progenitor cells was significantly greater in EPO-treated animals. The herein shown acceleration of healing by EPO may represent a promising novel treatment strategy for fractures with delayed healing and non-union formation.

Cerebral tissue repair and atrophy after embolic stroke in rat: A magnetic resonance imaging study of erythropoietin therapy

Using magnetic resonance imaging (MRI) protocols of T(2)-, T(2)*-, diffusion- and susceptibility-weighted imaging (T2WI, T2*WI, DWI, and SWI, respectively) with a 7T system, we tested the hypothesis that treatment of embolic stroke with erythropoietin (EPO) initiated at 24 hr and administered daily for 7 days after stroke onset has benefit in repairing ischemic cerebral tissue. Adult Wistar rats were subjected to embolic stroke by means of middle cerebral artery occlusion (MCAO) and were randomly assigned to a treatment (n = 11) or a control (n = 11) group. The treated group was given EPO intraperitoneally at a dose of 5,000 IU/kg daily for 7 days starting 24 hr after MCAO. Controls were given an equal volume of saline. MRI was performed at 24 hr and then weekly for 6 weeks. MRI and histological measurements were compared between groups. Serial T2WI demonstrated that expansion of the ipsilateral ventricle was significantly reduced in the EPO-treated rats. The volume ratio of ipsilateral parenchymal tissue relative to the contralateral hemisphere was significantly increased after EPO treatment compared with control animals, indicating that EPO significantly reduces atrophy of the ipsilateral hemisphere, although no significant differences in ischemic lesion volume were observed between the two groups. Angiogenesis and white matter remodeling were significantly increased and occurred earlier in EPO-treated animals than in the controls, as evident from T2*WI and diffusion anisotropy maps, respectively. These data indicate that EPO treatment initiated 24 hr poststroke promotes angiogenesis and axonal remodeling in the ischemic boundary, which may potentially reduce atrophy of the ipsilateral hemisphere.

Oxidative Stress and Protective Effect of Erythropoietin on Methotrexate-induced Esophageal Damage

An experimental study was conducted to investigate the role of oxidative stress and effects of erythropoietin (EPO) on methotrexate-induced esophageal damage. Twenty-four female Sprague-Dawley rats were equally divided into 3 groups: Sham operation animals (group S) were administered subcutaneous injections of 0.2 mL of 0.9% NaCl; control animals (group MTX) were administered subcutaneous injections of methotrexate (5 mg/kg) and EPO-treated animals (group EPO) were administered subcutaneous injections of methotrexate (5 mg/kg) and EPO (2000 IU/kg) once daily for 4 consecutive days. At the fifth day, the distal 1.5-cm esophageal segments were harvested for biochemical and histologic investigations. Oxidative damage was assessed by measuring the levels of malondialdehyde and nitric oxide, and activities of superoxide dismutase and catalase in homogenized samples of esophageal tissue. Histologic damage to esophageal tissue was scored and total tissue damage scores were calculated. Malondialdehyde levels in the S and EPO groups were significantly lower than those in the MTX group (P<0.05). Catalase and superoxide dismutase activities, and nitric oxide levels in the S and EPO groups were significantly higher than those in the MTX group (P<0.05). Esophageal tissue damage was significantly less in the EPO group than that in the MTX group (P<0.05). Free radicals elevate in methotrexate given rats' esophagus and EPO has significant preventive effects on methotrexate-induced oxidative damage of esophagus in a rat model.

Erythropoietin improved initial resuscitation and increased survival after cardiac arrest in rats

Introduction Recent data have demonstrated potent cardioprotective and neuroprotective effects of the application of growth hormones like erythropoietin (EPO) after focal cardiac or cerebral ischemia. In order to assess possible benefits regarding survival and resuscitation conditions, EPO was tested against placebo in a model of cardiac arrest in the rat. Methods Thirty-four male Wistar rats were randomized into two groups (EPO versus control; n = 17 per group). Under anesthesia, cardiac arrest was induced by asphyxia after neuromuscular blockade. After 6 min of global ischemia, animals were resuscitated by external chest compression combined with epinephrine administration. An intravenous bolus of recombinant human EPO (rhEPO, 3000 UI kg −1 body weight, i.v.) or saline (in control group) was performed 15 min before cardiac arrest, by a blinded investigator. Restoration of spontaneous circulation (ROSC), survival at 1, 24, 48 and 72 h and hemodynamic changes after cardiac arrest were studied. Results Survival to 72 h was significantly improved in the EPO group ( n = 15/17) compared to the control group ( n = 7/17). All the EPO-treated rats were successfully resuscitated whereas only 13 of 17 control animals resuscitated. EPO-treated animals required a significantly smaller dose of epinephrine before resuscitation, compared to control rats. Time course of systolic arterial blood pressure after resuscitation revealed no significant differences between both groups. Conclusion EPO, when administrated before cardiac arrest, improved initial resuscitation and increased the duration of post-resuscitation survival.

Erythropoietin reduces ischemia-reperfusion injury after liver transplantation in rats

Human recombinant Erythropoietin (rHuEpo) has recently been shown to be a potent protector of ischemia- reperfusion injury in warm-liver ischemia. Significant enhancement of hepatic regeneration and survival after large volume partial hepatic resection has also been demonstrated. It was the aim of this study to evaluate the capacities of rHuEpo in the setting of rat liver transplantation. One-hundred-and-twenty Wistar rats were used: 60 recipients received liver transplantation following donor organ treatment (60 donors) with either 1000 IU rHuEpo or saline injection (controls) into portal veins (cold ischemia 18 h, University of Wisconsin (UW) solution). Recipients were allocated to two groups, which either received 1000 IU rHuEpo at reperfusion or an equal amount of saline (control). Animals were sacrificed at defined time-points (2, 4.5, 24, 48 h and 7 days postoperatively) for analysis of liver enzymes, histology [hematoxylin-eosin (HE) staining, periodic acid Schiff staining (PAS)], immunostaining [terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), Hypoxyprobe] and real-time polymerase chain reaction (RT-PCR) of cytokine mRNA (IL-1, IL-6). Lactate dehydrogenase (LDH) and alanine aminotransferase (ALT) values were significantly reduced among the epo-treated animals 24 and 48 h after liver transplantation (LT). The TUNEL and Hypoxyprobe analyses as well as necrotic index evaluation displayed significant reduction of apoptosis and necrosis in rHuEpo-treated graft livers. Erythropoietin reduces ischemia-reperfusion injury after orthotopic liver transplantation in rats.

Erythropoietin administration after myocardial infarction in mice attenuates ischemic cardiomyopathy associated with enhanced homing of bone marrow‐derived progenitor cells via the CXCR‐4/SDF‐1 axis

Mobilization of bone marrow-derived stem cells (BMCs) was shown to have protective effects after myocardial infarction (MI). However, the classical mobilizing agent, granulocyte-colony stimulating factor (G-CSF) relapsed after revealing an impaired homing capacity. In the search for superior cytokines, erythropoietin (EPO) appears to be a promising agent. Therefore, we analyzed in a murine model of surgically induced MI the influence of EPO treatment on survival and functional parameters as well as BMC mobilization, homing, and effect on resident cardiac stem cells (CSCs). Human EPO was injected intraperitoneally after ligation of the left anterior descendens (LAD) for 3 days with a total dose of 5000 IU/kg 6 and 30 days after MI, and pressure volume relationships were investigated in vivo. Cardiac tissues were analyzed by histology. To show the effect on BMCs and CSCs, FACS analyses were performed. Homing factors were analyzed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and ELISA. EPO-treated animals showed a significant improvement of survival post-MI (62 vs. 36%). At days 6 and 30, all hemodynamic parameters associated with attenuated remodeling, enhanced neovascularization, and diminished apoptotic cells in the peri-infarct area were improved. BMC subpopulations (CD31(+), c-kit(+), and Sca-1(+) cells) were mobilized, and homing of Sca-1(+) and CXCR4(+) BMCs toward an SDF-1 gradient into the ischemic myocardium was enhanced. However, there was no beneficial effect on CSCs. We have shown that EPO application after MI shows cardioprotective effects. This may be explained by mobilization of BMCs, which are homing via the CXCR-4/SDF-1 axis. However, EPO has no beneficial effects on resident CSCs. Therefore, new treatment regimes using EPO together with other agents may combine complementary beneficial effects preventing ischemic cardiomyopathy.

Erythropoietin improves functional and histological recovery of traumatized skeletal muscle tissue

Apart from its hematopoietic effect, erythropoietin (EPO) is known as pleiotropic cytokine with anti-inflammatory and anti-apoptotic properties. Here, we evaluated for the first time the EPO-dependent regeneration capacity in an in vivo rat model of skeletal muscle trauma. A myoblast cell line was used to study the effect of EPO on serum deprivation-induced cell apoptosis in vitro. A crush injury was performed to the left soleus muscle in 80 rats treated with either EPO or saline. Muscle recovery was assessed by analysis of contraction capacities. Intravital microscopy, BrdU/laminin double immunohistochemistry and cleaved caspase-3 immunohistochemistry of muscle tissue on days 1, 7, 14, and 42 posttrauma served for assessment of local microcirculation, tissue integrity, and cell proliferation. Serum deprivation-induced myoblast apoptosis of 23.9 +/- 1.5% was reduced by EPO to 17.2 +/- 0.8%. Contraction force analysis in the EPO-treated animals revealed significantly improved muscle strength with 10-20% higher values of twitch and tetanic forces over the 42-day observation period. EPO-treated muscle tissue displayed improved functional capillary density as well as reduced leukocytic response and consecutively macromolecular leakage over day 14. Concomitantly, muscle histology showed significantly increased numbers of BrdU-positive satellite cells and interstitial cells as well as slightly lower counts of cleaved caspase-3-positive interstitial cells. EPO results in faster and better regeneration of skeletal muscle tissue after severe trauma and goes along with improved microcirculation. Thus, EPO, a compound established as clinically safe, may represent a promising therapeutic option to optimize the posttraumatic course of muscle tissue healing.

Effects of Erythropoietin on Blood-Brain Barrier Disruption in Focal Cerebral Ischemia

This study was performed to test whether systemically administered erythropoietin (EPO) could attenuate the blood-brain barrier (BBB) disruption in focal ischemia. Rats were injected intraperitoneally with 2,500 IU/kg of recombinant human EPO or normal saline 24 h before middle cerebral artery (MCA) occlusion. The transfer coefficient (Ki) of ¹⁴C-α-aminoisobutyric acid was determined to measure the degree of BBB disruption 1 h after MCA occlusion. In the control animals, the Ki of the ischemic cortex (IC) was significantly higher than that of the contralateral cortex (CC; +128%, p = 0.0002). In the EPO-treated animals, the Ki of the IC was not significantly different from that of the CC and was significantly lower (–44%, p = 0.003) than that of the control animals. Our data suggest that MCA occlusion increased BBB disruption, and the disruption was attenuated with EPO pretreatment.

Paracrine Suppression of VEGF Secretion by Erythropoietin Inhibits Tumor Growth.

Several studies have reported that erythropoietin (Epo) is a pleiotropic cytokine with biological properties in addition to its primary function in regulating maturation, growth and survival along the erythroid lineage. Recently, a number of investigators have reported that various neoplastic tissues and human cancer cell lines express Epo and the Epo receptor (EpoR), raising suspicion for the presence of an autocrine-paracrine Epo-EpoR system. It has been shown that inhibition of vascular endothelial growth factor (VEGF) results in an increase of Epo secretion and increased hematocrit in vivo. In this study, we used an in vivo Lewis lung carcinoma model to examine a converse Epo effect on VEGF production and metastasis. Lewis lung carcinoma (LLC) cells were injected subcutaneously into C57BL mice. The plasma levels of VEGF, the tumor vessel formation, the size of the primary tumors and the extent of lung metastatic disease were determined. In addition, intravenously injected LLC cells seeded in the lungs were assessed. Tumor-bearing animals treated with Epo had 23.6% less VEGF in the plasma compared to saline treated mice (p<0.04). There was no correlation between VEGF concentration and hemoglobin levels in either group of animals. Tumor sections indicated that the number of blood vessels was higher (10.7% for inner and 23.8% for outer, respectively) in tumors obtained from animals treated with saline compared to Epo-treated mice (p>0.05). Using non-parametric analysis, we found that there was a statistically significant difference in tumor growth between saline-treated and Epo-treated animals (p<0.05). However, the number of lung metastases derived from primary tumors was similar in both groups. In assessing size of the metastatic tumors, we found that the average volume of lung nodules was 24.2% higher in saline-injected animals compared to Epo-treated mice. The number of tumors seeded in the lungs following intravenous injection of LLC cells was similar in animals treated with a high dosage of Epo, low dosage of Epo or saline. In addition, the average volume of the nodules was reduced by 42% in animals treated with high and low concentrations of Epo compared to the control group (p = 0.03). In conclusion, Epo exerts a paracrine suppressive effect on VEGF secretion resulting in slower tumor growth in this model.