Erythropoietin In Animal Models Research Articles

Carbamoylated erythropoietin induces a neurotrophic gene profile in neuronal cells

Erythropoietin (EPO), a cytokine molecule, is best-known for its role in erythropoiesis. Preclinical studies have demonstrated that EPO has robust neuroprotective effects that appear to be independent of erythropoiesis. It is also being clinically tested for the treatment of neuropsychiatric illnesses due to its behavioral actions. A major limitation of EPO is that long-term administration results in excessive red blood cell production and increased blood viscosity. A chemical modification of EPO, carbamoylated erythropoietin (CEPO), reproduces the behavioral response of EPO in animal models but does not stimulate erythropoiesis. The molecular mechanisms involved in the behavioral effects of CEPO are not known. To obtain molecular insight we examined CEPO induced gene expression in neuronal cells. PC-12 cells were treated with CEPO followed by genome-wide microarray analysis. We investigated the functional significance of the gene profile by unbiased bioinformatics analysis. The Ingenuity pathway analysis (IPA) software was employed. The results revealed activation of functions such as neuronal number and long-term potentiation. Regulated signaling cascades included categories such as neurotrophin, CREB, NGF and synaptic long-term potentiation signaling. Some of the regulated genes from these pathways are CAMKII, EGR1, FOS, GRIN1, KIF1B, NOTCH1. We also comparatively examined EPO and CEPO-induced gene expression for a subset of genes in the rat dentate gyrus. The CEPO gene profile shows the induction of genes and signaling cascades that have roles in neurogenesis and memory formation, mechanisms that can produce antidepressant and cognitive function enhancing activity.

Erythropoietin and glucose homeostasis in women at varying degrees of future diabetic risk

Aims/BackgroundRecently, there has been considerable interest in the potential anti-diabetic effects of erythropoietin in animal models. It is not known, however, whether endogenous erythropoietin is associated with glucose regulation in humans. MethodsWe evaluated the longitudinal relationship between endogenous erythropoietin at 3-months postpartum and glucose homeostasis at 12-months postpartum in a cohort of 229 women with varying degrees of glucose intolerance in their recent pregnancy, a model of the early natural history of pre-diabetes/diabetes. The women reflected the full spectrum of glucose tolerance in pregnancy from normal (n=63) to mildly abnormal (n=65) to gestational impaired glucose tolerance (n=46) to gestational diabetes (n=55), and hence a broad range of future diabetic risk. ResultsAt 3-months postpartum, there was no difference in serum erythropoietin between these 4 groups (p=0.22). After covariate adjustment, erythropoietin was not associated with beta-cell function, insulin sensitivity, or glycemia at either 3- or 12-months postpartum. On multiple linear regression analyses, however, erythropoietin at 3-months emerged as an independent predictor of both systolic (beta=0.51326, p=0.003) and diastolic blood pressure (beta=0.3321, p=0.01) at 12-months. ConclusionEndogenous erythropoietin is not associated with glucose homeostasis early in the natural history of metabolic disease, but may be relevant to vascular health.

What is the Role of Erythropoietin in Acute Myocardial Infarct? Bridging the Gap Between Experimental Models and Clinical Trials

Erythropoietin (EPO) is the main hormone that regulates erythropoiesis. Beyond its well-known hematopoietic action, EPO has diverse cellular effects in non-hematopoietic tissues. It has been shown to inhibit apoptosis by activating pro-survival pathways in the myocardium, to mobilize endothelial progenitor cells and to inhibit migration of inflammatory cells. EPO has also been shown to have potent pro-angiogenic properties. Numerous experimental data support the cardioprotective effects of EPO in animal models of acute myocardial infarct (AMI). However, these findings are not supported by recent clinical trials designed to investigate the safety and efficacy of EPO in patients with AMI. In this article, we begin by providing a comprehensive review of the cardioprotective effects of EPO in experimental animal models and the molecular mechanisms underlying these effects. We then discuss the EPO data obtained through clinical trials. We compare similarities and differences between the animal and human studies as well as between the different clinical studies in terms of sample size and study design including the dose, the route and the timing of administration as well as confounding factors such as comorbidities and concomitant treatments. Finally, we question the gap between the experimental and the translational clinical data and propose further developments to address these discrepancies and clearly evaluate the role of EPO in the clinical setting of MI.

Review of Tissue-Protective Cytokines

Review of Tissue-Protective Cytokines

Darbepoetin enhances endothelium-dependent vasomotor function in patients with stable coronary artery disease only after preceding ischaemia/reperfusion

Vasoprotective effects of erythropoietin in animal models are mediated by endothelium-derived NO and/or mobilization of EPCs (endothelial progenitor cells) and may be enhanced by ischaemia: whether they are present in humans is unknown. We examined whether the erythropoietin analogue darbepoetin improves FMD (flow-mediated dilatation), a measure of endothelium-derived NO, and whether this is influenced by preceding I/R (ischaemia/reperfusion). A total of 36 patients (50-75 years) with stable coronary artery disease were randomized to receive a single dose of darbepoetin (300 μg) or saline placebo. FMD was measured at the brachial artery using high-resolution ultrasound. CD133⁺/CD34⁺/VEGFR2⁺ (vascular endothelial growth factor receptor 2) circulating EPCs were enumerated by flow cytometry. Measurements were made immediately before darbepoetin/placebo and at 24 h, 72 h and 7 days. At 24 h, FMD was repeated after 20 min of I/R of the upper limb. A further group of 11 patients was studied according to the same protocol, all receiving darbepoetin, with omission of forearm I/R at 24 h. Immunoreactive erythropoietin peaked at 24 h and remained elevated at approximately 50-fold of baseline at 72 h. FMD did not differ significantly between groups at 24 h (before I/R). At 72 h (48 h after I/R), FMD was greater (by 2.3±0.5% in the darbepoetin compared with the placebo group, a 66% increase over baseline; P<0.001) and greater than FMD at the same time point without preceding I/R (P<0.01). Increases in CD133⁺/CD34⁺/VEGFR2⁺ cells after darbepoetin did not differ according to the presence or absence of preceding I/R. Preceding I/R is required for darbepoetin to enhance endothelial function, possibly by increasing expression of the erythropoietin receptor and by a mechanism likely to involve Akt/NO rather than circulating EPCs.

Erythropoietin improves memory function with reducing endothelial dysfunction and amyloid‐beta burden in Alzheimer’s disease models

Neurovascular degeneration contributes to the pathogenesis of Alzheimer's disease (AD). Because erythropoietin (EPO) promotes endothelial regeneration, we investigated the therapeutic effects of EPO in animal models of AD. In aged Tg2576 mice, EPO receptors (EPORs) were expressed in the cortex and hippocampus. Tg2576 mice were treated with daily injection of EPO (5000 IU/kg/day) for 5 days. At 14 days, EPO improved contextual memory as measured by fear-conditioning test. EPO enhanced endothelial proliferation and the level of synaptophysin expression in the brain. EPO also increased capillary density, and decreased the level of the receptor for advanced glycation endproducts (RAGE) in the brain, while decreasing in the amount of amyloid plaque and amyloid-β (Aβ). In cultured human endothelial cells, EPO enhanced angiogenesis and suppressed the expression of the RAGE. These results show that EPO improves memory and ameliorates endothelial degeneration induced by Aβ in AD models. This pre-clinical evidence suggests that EPO may be useful for the treatment of AD.

48 Darbepoetin enhances endothelial-dependent vasomotor function in patients with stable coronary artery disease only after preceding ischaemia-reperfusion

BackgroundVasoprotective effects of erythropoietin in animal models are mediated by endothelium-derived nitric oxide (NO) and/or mobilisation of endothelial progenitor cells (EPC) and may be enhanced by ischaemia; whether they are...

297 DARBEPOETIN ENHANCES ENDOTHELIUM-DEPENDENT VASOMOTOR FUNCTION IN PATIENTS WITH STABLE CORONARY ARTERY DISEASE ONLY AFTER PRECEDING ISCHAEMIA-REPERFUSION

Vasoprotective effects of erythropoietin in animal models are mediated by endothelium-derived NO and/or mobilization of EPCs (endothelial progenitor cells) and may be enhanced by ischaemia: whether they are present in humans is unknown. We examined whether the erythropoietin analogue darbepoetin improves FMD (flow-mediated dilatation), a measure of endotheliumderived NO, and whether this is influenced by preceding I/R (ischaemia/reperfusion). A total of 36 patients (50–75 years) with stable coronary artery disease were randomized to receive a single dose of darbepoetin (300 μg) or saline placebo. FMD was measured at the brachial artery using high-resolution ultrasound. CD133 + /CD34 + /VEGFR2 + (vascular endothelial growth factor receptor 2) circulating EPCs were enumerated by flow cytometry. Measurements were made immediately before darbepoetin/placebo and at 24 h, 72 h and 7 days. At 24 h, FMD was repeated after 20 min of I/R of the upper limb. A further group of 11 patients was studied according to the same protocol, all receiving darbepoetin, with omission of forearm I/R at 24 h. Immunoreactive erythropoietin peaked at 24 h and remained elevated at approximately 50-fold of baseline at 72 h. FMD did not differ significantly between groups at 24 h (before I/R). At 72 h (48 h after I/R), FMD was greater (by 2.3 + 0.5 % in the darbepoetin compared with the placebo group, a 66 % increase over baseline; P < 0.001) and greater than FMD at the same time point without preceding I/R (P < 0.01). Increases in CD133 + /CD34 + /VEGFR2 + cells after darbepoetin did not differ according to the presence or absence of preceding I/R. Preceding I/R is required for darbepoetin to enhance endothelial function, possibly by increasing expression of the erythropoietin receptor and by a mechanism likely to involve Akt/NO rather than circulating EPCs.

Post-acute delivery of erythropoietin induces stroke recovery by promoting perilesional tissue remodelling and contralesional pyramidal tract plasticity

The promotion of post-ischaemic motor recovery remains a major challenge in clinical neurology. Recently, plasticity-promoting effects have been described for the growth factor erythropoietin in animal models of neurodegenerative diseases. To elucidate erythropoietin's effects in the post-acute ischaemic brain, we examined how this growth factor influences functional neurological recovery, perilesional tissue remodelling and axonal sprouting of the corticorubral and corticobulbar tracts, when administered intra-cerebroventricularly starting 3 days after 30 min of middle cerebral artery occlusion. Erythropoietin administered at 10 IU/day (but not at 1 IU/day), increased grip strength of the contralesional paretic forelimb and improved motor coordination without influencing spontaneous locomotor activity and exploration behaviour. Neurological recovery by erythropoietin was associated with structural remodelling of ischaemic brain tissue, reflected by enhanced neuronal survival, increased angiogenesis and decreased reactive astrogliosis that resulted in reduced scar formation. Enhanced axonal sprouting from the ipsilesional pyramidal tract into the brainstem was observed in vehicle-treated ischaemic compared with non-ischaemic animals, as shown by injection of dextran amines into both motor cortices. Despite successful remodelling of the perilesional tissue, erythropoietin enhanced axonal sprouting of the contralesional, but not ipsilesional pyramidal tract at the level of the red and facial nuclei. Moreover, molecular biological and histochemical studies revealed broad anti-inflammatory effects of erythropoietin in both hemispheres together with expression changes of plasticity-related molecules that facilitated contralesional axonal growth. Our study establishes a plasticity-promoting effect of erythropoietin after stroke, indicating that erythropoietin acts via recruitment of contralesional rather than of ipsilesional pyramidal tract projections.

Intranasal erythropoietin therapy in nervous system disorders

Importance of the field: Erythropoietin (EPO) is a growth hormone and cytokine that plays an important role in erythropoiesis and neuroprotection. However, EPO treatment for neurological diseases requires repeated injections or high-dose systemic administration, which may cause systemic side effects. The lack of any effective treatment of acute and chronic neurodegenerative diseases and the promising outcome by EPO in animal models in vivo demand a critical evaluation of intranasal EPO delivery to the brain as an alternative administration method.Areas covered in this review: The current use and intranasal administration of EPO and its derivatives in preclinical studies and recent clinical trials with EPO in neurological diseases.What the reader will gain: This paper gives an overview of the therapeutic considerations of intranasal EPO and EPO derivatives for neuroprotection.Take home message: Intranasal delivery (ID) of neuroprotective drugs is an area of great interest. Among the administration strategies used at present, ID of EPO is the most promising. Further preclinical and clinical studies are needed to evaluate the potential significance of this alternative route for increasing EPO bioavailability and decreasing side effects.

A Systematic Review and Meta-Analysis of Erythropoietin in Experimental Stroke

Erythropoietin (EPO) has shown promise as a neuroprotectant in animal models of ischemic stroke. EPO is thought not only to protect neurons from cell death, but also to promote regeneration after stroke. Here, we report a systematic review and meta-analysis of the efficacy of EPO in animal models of focal cerebral ischemia. Primary outcomes were infarct size and neurobehavioral outcome. Nineteen studies involving 346 animals for infarct size and 425 animals for neurobehavioral outcome met our inclusion criteria. Erythropoietin improved infarct size by 30.0% (95% CI: 21.3 to 38.8) and neurobehavioral outcome by 39.8% (33.7 to 45.9). Studies that randomized to treatment group or that blinded assessment of outcome showed lower efficacy. Erythropoietin was tested in animals with hypertension in no studies reporting infarct size and in 7.5% of the animals reporting neurobehavioral outcome. These findings show efficacy for EPO in experimental stroke, but when the impact of common sources of bias are considered, this efficacy falls, suggesting we may be overestimating its potential benefit. As common human co-morbidities may reduce therapeutic efficacy, broader testing to delineate the range of circumstances in which EPO works best would be beneficial.