Angiogenesis and plasticity: role of erythropoietin in vascular systems

The role of anemia on admission in acute coronary syndrome - An umbrella review of systematic reviews and meta-analyses

INTRODUCTION

The role of erythrocytes in the acute coronary syndrome (ACS) is complex. The aim of this review in terms of PICO (P: patients; I: intervention; C: comparison; O: outcome) was to summarize systematic reviews in patients (P) with acute coronary syndrome, evaluating the effects of (I) 1) iron deficiency, 2) administration of an erythropoiesis-stimulating agent (ESA), 3) anemia on admission, 4) red blood cell transfusion, 5) a restrictive transfusion strategy in comparison (C) to 1) no iron deficiency, 2) no ESA 3) no anemia on admission, 4) no red blood cell transfusion, 5) a liberal transfusion strategy on mortality (O).

METHODS

We used AMSTAR2 to assess the methodological quality of systematic reviews and grade the available research. The primary endpoint was all-cause mortality.

RESULTS

Using the data from 2,787,005 patients, the following conditions were associated with worse outcome in patients with ACS: anemia on admission (RR 2.08 95%CI 1.70-2.55) and transfusion (1.93 95%CI 1.12-3.34) of red blood cells. A liberal transfusion (RR 0.86 95%CI 0.70-1-05), administration of ESA (RR 0.55 95%CI 0.22-1.33) and iron deficiency (OR 1.24 95%CI 0.12-13.13) were not associated with altered all-cause mortality.

CONCLUSION

Patients suffering from ACS and anemia on admission are at particular risk for adverse outcome. There is evidence of associations between adverse outcomes and receiving red blood cell transfusions.

Nicotinamide as a Foundation for Treating Neurodegenerative Disease and Metabolic Disorders

Neurodegenerative disorders impact more than one billion individuals worldwide and are intimately tied to metabolic disease that can affect another nine hundred individuals throughout the globe. Nicotinamide is a critical agent that may offer fruitful prospects for neurodegenerative diseases and metabolic disorders, such as diabetes mellitus. Nicotinamide protects against multiple toxic environments that include reactive oxygen species exposure, anoxia, excitotoxicity, ethanolinduced neuronal injury, amyloid (Aß) toxicity, age-related vascular disease, mitochondrial dysfunction, insulin resistance, excess lactate production, and loss of glucose homeostasis with pancreatic β-cell dysfunction. However, nicotinamide offers cellular protection in a specific concentration range, with dosing outside of this range leading to detrimental effects. The underlying biological pathways of nicotinamide that involve the silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), the mechanistic target of rapamycin (mTOR), AMP activated protein kinase (AMPK), and mammalian forkhead transcription factors (FoxOs) may offer insight for the clinical translation of nicotinamide into a safe and efficacious therapy through the modulation of oxidative stress, apoptosis, and autophagy. Nicotinamide is a highly promising target for the development of innovative strategies for neurodegenerative disorders and metabolic disease, but the benefits of this foundation depend greatly on gaining a further understanding of nicotinamide's complex biology.

New Insights for nicotinamide: Metabolic disease, autophagy, and mTOR

Metabolic disorders, such as diabetes mellitus (DM), are increasingly becoming significant risk factors for the health of the global population and consume substantial portions of the gross domestic product of all nations. Although conventional therapies that include early diagnosis, nutritional modification of diet, and pharmacological treatments may limit disease progression, tight serum glucose control cannot prevent the onset of future disease complications. With these concerns, novel strategies for the treatment of metabolic disorders that involve the vitamin nicotinamide, the mechanistic target of rapamycin (mTOR), mTOR Complex 1 (mTORC1), mTOR Complex 2 (mTORC2), AMP activated protein kinase (AMPK), and the cellular pathways of autophagy and apoptosis offer exceptional promise to provide new avenues of treatment. Oversight of these pathways can promote cellular energy homeostasis, maintain mitochondrial function, improve glucose utilization, and preserve pancreatic beta-cell function. Yet, the interplay among mTOR, AMPK, and autophagy pathways can be complex and affect desired clinical outcomes, necessitating further investigations to provide efficacious treatment strategies for metabolic dysfunction and DM.

Nicotinamide: Oversight of Metabolic Dysfunction Through SIRT1, mTOR, and Clock Genes

Metabolic disorders that include diabetes mellitus present significant challenges for maintaining the welfare of the global population. Metabolic diseases impact all systems of the body and despite current therapies that offer some protection through tight serum glucose control, ultimately such treatments cannot block the progression of disability and death realized with metabolic disorders. As a result, novel therapeutic avenues are critical for further development to address these concerns. An innovative strategy involves the vitamin nicotinamide and the pathways associated with the silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), the mechanistic target of rapamycin (mTOR), mTOR Complex 1 (mTORC1), mTOR Complex 2 (mTORC2), AMP activated protein kinase (AMPK), and clock genes. Nicotinamide maintains an intimate relationship with these pathways to oversee metabolic disease and improve glucose utilization, limit mitochondrial dysfunction, block oxidative stress, potentially function as antiviral therapy, and foster cellular survival through mechanisms involving autophagy. However, the pathways of nicotinamide, SIRT1, mTOR, AMPK, and clock genes are complex and involve feedback pathways as well as trophic factors such as erythropoietin that require a careful balance to ensure metabolic homeostasis. Future work is warranted to gain additional insight into these vital pathways that can oversee both normal metabolic physiology and metabolic disease.

Cognitive impairment with diabetes mellitus and metabolic disease: innovative insights with the mechanistic target of rapamycin and circadian clock gene pathways

Introduction: Dementia is the 7th leading cause of death that imposes a significant financial and service burden on the global population. Presently, only symptomatic care exists for cognitive loss, such as Alzheimer's disease.Areas covered: Given the advancing age of the global population, it becomes imperative to develop innovative therapeutic strategies for cognitive loss. New studies provide insight to the association of cognitive loss with metabolic disorders, such as diabetes mellitus.Expert opinion: Diabetes mellitus is increasing in incidence throughout the world and affects 350 million individuals. Treatment strategies identifying novel pathways that oversee metabolic and neurodegenerative disorders offer exciting prospects to treat dementia. The mechanistic target of rapamycin (mTOR) and circadian clock gene pathways that include AMP activated protein kinase (AMPK), Wnt1 inducible signaling pathway protein 1 (WISP1), erythropoietin (EPO), and silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1) provide novel strategies to treat cognitive loss that has its basis in metabolic cellular dysfunction. However, these pathways are complex and require precise regulation to maximize treatment efficacy and minimize any potential clinical disability. Further investigations hold great promise to treat both the onset and progression of cognitive loss that is associated with metabolic disease.

Warming Up to New Possibilities with the Capsaicin Receptor TRPV1: mTOR, AMPK, and Erythropoietin

BACKGROUND

Transient receptor potential (TRP) channels are a superfamily of ion channels termed after the trp gene in Drosophila that are diverse in structure and control a wide range of biological functions including cell development and growth, thermal regulation, and vascular physiology. Of significant interest is the transient receptor potential cation channel subfamily V member 1 (TRPV1) receptor, also known as the capsaicin receptor and the vanilloid receptor 1, that is a non-selective cation channel sensitive to a host of external stimuli including capsaicin and camphor, venoms, acid/basic pH changes, and temperature.

METHODS

Given the multiple modalities that TRPV1 receptors impact in the body, we examined and discussed the role of these receptors in vasomotor control, metabolic disorders, cellular injury, oxidative stress, apoptosis, autophagy, and neurodegenerative disorders and their overlap with other signal transduction pathways that impact trophic factors.

RESULTS

Surprisingly, TRPV1 receptors do not rely entirely upon calcium signaling to affect cellular biology, but also have a close relationship with the mechanistic target of rapamycin (mTOR), AMP activated protein kinase (AMPK), and protein kinase B (Akt) that have roles in pain sensitivity, stem cell development, cellular survival, and cellular metabolism. These pathways with TRPV1 converge in the signaling of growth factors with recent work highlighting a relationship with erythropoietin (EPO). Angiogenesis and endothelial tube formation controlled by EPO requires, in part, the activation of TRPV1 receptors in conjunction with Akt and AMPK pathways.

CONCLUSION

TRPV1 receptors could prove to become vital to target disorders of vascular origin and neurodegeneration. Broader and currently unrealized implementations for both EPO and TRPV1 receptors can be envisioned for for the development of novel therapeutic strategies in multiple systems of the body.

Possible Inhibitory Effect of Erythropoiesis-Stimulating Agents at the Predialysis Stage on Early-Phase Coronary Events after Hemodialysis Initiation

BACKGROUND

We examined whether the use of erythropoiesis-stimulating agents (ESAs) to correct anemia at the predialysis stage could inhibit early-phase coronary events after hemodialysis initiation.

METHODS

We enrolled 242 patients with chronic kidney disease who had received continued medical treatments and initiated maintenance hemodialysis from 1 September 2000 to 31 December 2014 at Toujinkai Hospital. Patients with a previous history of blood transfusion or any cardiovascular events or interventions were excluded. The coronary events were followed for 1 year after initiation of hemodialysis.

RESULTS

Coronary events occurred in 51 of 242 patients: 10 patients had acute coronary syndrome [9 with percutaneous coronary intervention (PCI), 1 without intervention], and 41 had elective coronary revascularization (38 PCI and 3 coronary artery bypass graft). ESA was administered in 118 of 242 patients (48.8%). In stepwise logistic analysis, coronary events were positively associated with nonuse of ESA at the predialysis stage (odds ratio 2.66, p = 0.005) and diabetes mellitus (odds ratio 5.33, p < 0.001). When dividing the patients into 4 subgroups by blood hemoglobin (Hb) level (8.5 g/dl) and the use/nonuse of ESA, coronary event-free survival rates were higher (p = 0.005) in those with Hb ≥8.5 g/dl, ESA+ (86.6%, n = 82) and tended to be higher (p = 0.055) in those with Hb <8.5 g/dl, ESA+ (86.1%, n = 36) than in patients with Hb <8.5 g/dl, ESA- (68.6%, n = 86) in a Kaplan-Meier analysis.

CONCLUSIONS

The use of ESA to correct anemia at the predialysis stage may inhibit early-phase coronary events after hemodialysis initiation.

Erythropoietin and Nonhematopoietic Effects

Erythropoietin (EPO) is the main regulator of red blood cell production. Since the 1990s, EPO has been used for the treatment of anemia associated with end-stage renal failure and chemotherapy. The erythropoietin receptors were found on other organs such as the brain, spinal cord, heart and skin. In addition, it has been shown that many tissues produce and locally release EPO in response to hypoxic, biochemical and physical stress. In cellular, animal and clinical studies, EPO protects tissues from ischemia and reperfusion injury, has antiapoptotic effects and improves regeneration after injury. In this article, we mainly review the nonhematopoietic effects and new possible clinical indications for EPO.

Neonatal Encephalopathy: Update on Therapeutic Hypothermia and Other Novel Therapeutics

Neonatal encephalopathy (NE) is a major cause of neonatal mortality and morbidity. Therapeutic hypothermia (TH) is standard treatment for newborns at 36 weeks of gestation or greater with intrapartum hypoxia-related NE. Term and late preterm infants with moderate to severe encephalopathy show improved survival and neurodevelopmental outcomes at 18 months of age after TH. TH can increase survival without increasing major disability, rates of an IQ less than 70, or cerebral palsy. Neonates with severe NE remain at risk of death or severe neurodevelopmental impairment. This review discusses the evidence supporting TH for term or near term neonates with NE.

Erythropoietin and a nonerythropoietic peptide analog promote aortic endothelial cell repair under hypoxic conditions: role of nitric oxide

The cytoprotective effects of erythropoietin (EPO) and an EPO-related nonerythropoietic analog, pyroglutamate helix B surface peptide (pHBSP), were investigated in an in vitro model of bovine aortic endothelial cell injury under normoxic (21% O₂) and hypoxic (1% O₂) conditions. The potential molecular mechanisms of these effects were also explored. Using a model of endothelial injury (the scratch assay), we found that, under hypoxic conditions, EPO and pHBSP enhanced scratch closure by promoting cell migration and proliferation, but did not show any effect under normoxic conditions. Furthermore, EPO protected bovine aortic endothelial cells from staurosporine-induced apoptosis under hypoxic conditions. The priming effect of hypoxia was associated with stabilization of hypoxia inducible factor-1α, EPO receptor upregulation, and decreased Ser-1177 phosphorylation of endothelial nitric oxide synthase (NOS); the effect of hypoxia on the latter was rescued by EPO. Hypoxia was associated with a reduction in nitric oxide (NO) production as assessed by its oxidation products, nitrite and nitrate, consistent with the oxygen requirement for endogenous production of NO by endothelial NOS. However, while EPO did not affect NO formation in normoxia, it markedly increased NO production, in a manner sensitive to NOS inhibition, under hypoxic conditions. These data are consistent with the notion that the tissue-protective actions of EPO-related cytokines in pathophysiological settings associated with poor oxygenation are mediated by NO. These findings may be particularly relevant to atherogenesis and postangioplasty restenosis.

Charting a course for erythropoietin in traumatic brain injury

Traumatic brain injury (TBI) is a severe public health problem that impacts more than four million individuals in the United States alone and is increasing in incidence on a global scale. Importantly, TBI can result in acute as well as chronic impairments for the nervous system leaving individuals with chronic disability and in instances of severe trauma, death becomes the ultimate outcome. In light of the significant negative health consequences of TBI, multiple therapeutic strategies are under investigation, but those focusing upon the cytokine and growth factor erythropoietin (EPO) have generated a great degree of enthusiasm. EPO can control cell death pathways tied to apoptosis and autophagy as well oversees processes that affect cellular longevity and aging. In vitro studies and experimental animal models of TBI have shown that EPO can restore axonal integrity, promote cellular proliferation, reduce brain edema, and preserve cellular energy homeostasis and mitochondrial function. Clinical studies for neurodegenerative disorders that involve loss of cognition or developmental brain injury support a positive role for EPO to prevent or reduce injury in the nervous system. However, recent clinical trials with EPO and TBI have not produced such clear conclusions. Further clinical studies are warranted to address the potential efficacy of EPO during TBI, the concerns with the onset, extent, and duration of EPO therapeutic strategies, and to focus upon the specific downstream pathways controlled by EPO such as protein kinase B (Akt), mechanistic target of rapamycin (mTOR), AMP activated protein kinase (AMPK), sirtuins, wingless pathways, and forkhead transcription factors for improved precision against the detrimental effects of TBI.

Erythropoietin and mTOR: A "One-Two Punch" for Aging-Related Disorders Accompanied by Enhanced Life Expectancy

Life expectancy continues to increase throughout the world, but is accompanied by a rise in the incidence of non-communicable diseases. As a result, the benefits of an increased lifespan can be limited by aging-related disorders that necessitate new directives for the development of effective and safe treatment modalities. With this objective, the mechanistic target of rapamycin (mTOR), a 289-kDa serine/threonine protein, and its related pathways of mTOR Complex 1 (mTORC1), mTOR Complex 2 (mTORC2), proline rich Akt substrate 40 kDa (PRAS40), AMP activated protein kinase (AMPK), Wnt signaling, and silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), have generated significant excitement for furthering novel therapies applicable to multiple systems of the body. Yet, the biological and clinical outcome of these pathways can be complex especially with oversight of cell death mechanisms that involve apoptosis and autophagy. Growth factors, and in particular erythropoietin (EPO), are one avenue under consideration to implement control over cell death pathways since EPO can offer potential treatment for multiple disease entities and is intimately dependent upon mTOR signaling. In experimental and clinical studies, EPO appears to have significant efficacy in treating several disorders including those involving the developing brain. However, in mature populations that are affected by aging-related disorders, the direction for the use of EPO to treat clinical disease is less clear that may be dependent upon a number of factors including the understanding of mTOR signaling. Continued focus upon the regulatory elements that control EPO and mTOR signaling could generate critical insights for targeting a broad range of clinical maladies.

Regeneration in the nervous system with erythropoietin

Globally, greater than 30 million individuals are afflicted with disorders of the nervous system accompanied by tens of thousands of new cases annually with limited, if any, treatment options. Erythropoietin (EPO) offers an exciting and novel therapeutic strategy to address both acute and chronic neurodegenerative disorders. EPO governs a number of critical protective and regenerative mechanisms that can impact apoptotic and autophagic programmed cell death pathways through protein kinase B (Akt), sirtuins, mammalian forkhead transcription factors, and wingless signaling. Translation of the cytoprotective pathways of EPO into clinically effective treatments for some neurodegenerative disorders has been promising, but additional work is necessary. In particular, development of new treatments with erythropoiesis-stimulating agents such as EPO brings several important challenges that involve detrimental vascular outcomes and tumorigenesis. Future work that can effectively and safely harness the complexity of the signaling pathways of EPO will be vital for the fruitful treatment of disorders of the nervous system.

Low Oxygen Tension Primes Aortic Endothelial Cells to the Reparative Effect of Tissue-Protective Cytokines

Erythropoietin (EPO) has both erythropoietic and tissue-protective properties. The EPO analogues carbamylated EPO (CEPO) and pyroglutamate helix B surface peptide (pHBSP) lack the erythropoietic activity of EPO but retain the tissue-protective properties that are mediated by a heterocomplex of EPO receptor (EPOR) and the β common receptor (βCR). We studied the action of EPO and its analogues in a model of wound healing where a bovine aortic endothelial cells (BAECs) monolayer was scratched and the scratch closure was assessed over 24 h under different oxygen concentrations. We related the effects of EPO and its analogues on repair to their effect on BAECs proliferation and migration (evaluated using a micro-Boyden chamber). EPO, CEPO and pHBSP enhanced scratch closure only at lower oxygen (5%), while their effect at atmospheric oxygen (21%) was not significant. The mRNA expression of EPOR was doubled in 5% compared with 21% oxygen, and this was associated with increased EPOR assessed by immunofluorescence and Western blot. By contrast, βCR mRNA levels were similar in 5% and 21% oxygen. EPO and its analogues increased both BAECs proliferation and migration, suggesting that both may be involved in the reparative process. The priming effect of low oxygen tension on the action of tissue-protective cytokines may be of relevance to vascular disease, including atherogenesis and restenosis.

Application of cell encapsulation for controlled delivery of biological therapeutics

Cell microencapsulation technology is likely to have an increasingly important role in new approaches rather than the classical and pioneering organ replacement. Apart from becoming a tool for protein and morphogen release and long-term drug delivery, it is becoming a new three-dimensional platform for stem cell research. Recent progress in the field has resulted in biodegradable scaffolds that are able to retain and release the cell content in different anatomical locations. Additional advances include the use biomimetic scaffolds that provide greater control over material-cell interactions and the development of more precise encapsulated cell-tracking systems. This review summarises the state of the art of cell microencapsulation and discusses the main directions and challenges of this field towards the controlled delivery of biological therapeutics.

Differential gene expression in Lin-/VEGF-R2+ bone marrow-derived endothelial progenitor cells isolated from diabetic mice

BACKGROUND

Diabetes is known to impair the number and function of endothelial progenitor cells in the circulation, causing structural and functional alterations in the micro- and macro-vasculature. The aim of this study was to identify early diabetes-related changes in the expression of genes that have been reported to be closely involved in endothelial progenitor cell migration and function.

METHODS

Based on review of current literature, this study examined the expression level of 35 genes that are known to be involved in endothelial progenitor cell migration and function in magnetically sorted Lin-/VEGF-R2+ endothelial progenitor cells obtained from the bone marrow of Akita mice in the early stages of diabetes (18 weeks) using RT-PCR and Western blotting. We used the Shapiro-Wilk and D'Agostino & Pearson Omnibus tests to assess normality. Differences between groups were evaluated by Student's t-test for normally distributed data (including Welch correction in cases of unequal variances) or Mann-Whitney test for not normally distributed data.

RESULTS

We observed a significant increase in the number of Lin-/VEGF-R2+ endothelial progenitor cells within the bone marrow in diabetic mice compared with non-diabetic mice. Two genes, SDF-1 and SELE, were significantly differentially expressed in diabetic Lin-/VEGF-R2+ endothelial progenitor cells and six other genes, CAV1, eNOS, CLDN5, NANOG, OCLN and BDNF, showed very low levels of expression in diabetic Lin-/VEGF-R2+ progenitor cells.

CONCLUSION

Low SDF-1 expression may contribute to the dysfunctional mobilization of bone marrow Lin-/VEGF-R2+ endothelial progenitor cells, which may contribute to microvascular injury in early diabetes.

Targeting Neovascularization in Ischemic Retinopathy: Recent Advances

Pathological retinal neovascularization (RNV) is a common micro-vascular complication in several retinal diseases including retinopathy of prematurity, diabetic retinopathy, age-related macular degeneration and central vein occlusion. The current therapeutic modalities of RNV are invasive and although they may slow or halt the progression of the disease they are unlikely to restore normal acuity. Therefore, there is an urgent need to develop treatment modalities, which are less invasive and therefore associated with fewer procedural complications and systemic side effects. This review article summarizes our understanding of the pathophysiology and current treatment of RNV in ischemic retinopathies; lists potential therapeutic targets; and provides a framework for the development of future treatment modalities.

Erythropoietin combined with ACE inhibitor prevents heart remodeling in 5/6 nephrectomized rats independently of blood pressure and kidney function

BACKGROUND

Cardiovascular disease is the primary cause of mortality in patients with chronic kidney disease (CKD). Heart remodeling in CKD comprises mainly interstitial fibrosis and capillary loss. Beyond correcting renal anemia, erythropoietin (Epo) has potentially beneficial pleiotropic effects on heart remodeling.

METHODS

12-week-old male Sprague-Dawley rats were randomized to 5/6 nephrectomy (NX) or sham operation (sham-op); subsequently, they received murine Epo (2.5 μg/kg/week), enalapril (12 mg/kg/day), Epo + enalapril, Epo + dihydralazine (25 mg/kg/day), or vehicle. Heart function and morphology was assessed after 16 weeks of treatment.

RESULTS

Compared with sham-op (81.2%), left ventricle fractional shortening was reduced in vehicle-treated NX (66.3%) and this was ameliorated by Epo (72.6%) and even prevented by enalapril (80.6%). Capillary length density was lower and the area of fibrosis more marked in vehicle-treated NX compared to sham-op. Capillary rarefaction and heart fibrosis were prevented in NX treated with Epo + enalapril and reduced in NX treated with enalapril and Epo + dihydralazine. Despite higher blood pressure, treatment with Epo reduced heart fibrosis but failed to prevent capillary loss. In parallel, expression of the p47phox NADPH oxidase was higher in untreated NX and was effectively reduced in NX treated with Epo + enalapril. Under basal conditions there was no difference between the groups regarding myocardial hypoxia as reflected by pimonidazole staining.

CONCLUSION

Epo in combination with enalapril caused additive reduction of cardiac fibrosis and microvessel disease in 5/6 nephrectomized rats presumably by decreasing myocardial oxidative stress.

Erythropoietin: new directions for the nervous system

New treatment strategies with erythropoietin (EPO) offer exciting opportunities to prevent the onset and progression of neurodegenerative disorders that currently lack effective therapy and can progress to devastating disability in patients. EPO and its receptor are present in multiple systems of the body and can impact disease progression in the nervous, vascular, and immune systems that ultimately affect disorders such as Alzheimer's disease, Parkinson's disease, retinal injury, stroke, and demyelinating disease. EPO relies upon wingless signaling with Wnt1 and an intimate relationship with the pathways of phosphoinositide 3-kinase (PI 3-K), protein kinase B (Akt), and mammalian target of rapamycin (mTOR). Modulation of these pathways by EPO can govern the apoptotic cascade to control β-catenin, glycogen synthase kinase-3β, mitochondrial permeability, cytochrome c release, and caspase activation. Yet, EPO and each of these downstream pathways require precise biological modulation to avert complications associated with the vascular system, tumorigenesis, and progression of nervous system disorders. Further understanding of the intimate and complex relationship of EPO and the signaling pathways of Wnt, PI 3-K, Akt, and mTOR are critical for the effective clinical translation of these cell pathways into robust treatments for neurodegenerative disorders.

Treating patients with schizophrenia deficit with erythropoietin?

This systematic review summarizes and critically appraises the literature on the effect of erythropoietin (EPO) in schizophrenia patients and the pathophysiological mechanisms that may explain the potential of its use in this disease. EPO is mainly known for its regulatory activity in the synthesis of erythrocytes and is frequently used in treatment of chronic anemia. This cytokine, however, has many other properties, some of which may improve the symptoms of psychiatric illness. The review follows the preferred reporting items for systematic reviews and meta-analysis (PRISMA) statement guidelines. Three databases (Medline, Web of Science, and Cochrane) were searched combining the search terms 'erythropoietin AND (psychotic disorders OR schizophrenia)'. Seventy-eight studies were included in qualitative synthesis, a meta-analytic approach being prohibited. The findings suggest that several EPO cerebral potential properties may be relevant for schizophrenia treatment, such as neurotransmission regulation, neuroprotection, modulation of inflammation, effects on blood-brain barrier permeability, effects on oxidative stress and neurogenesis. Several potentially detrimental side-effects of EPO therapy, such as increased risk of thrombosis, cancer, increased metabolic rate and mean arterial blood pressure leading to cerebral ischemia could severely limit or halt the use of EPO. Overall, because the available data are inconclusive, further efforts in this field are warranted.

Erythropoietin use and abuse

Recombinant human erythropoietin (rhEPO) is arguably the most successful therapeutic application of recombinant DNA technology till date. It was isolated in 1977 and the gene decoded in 1985. Since then, it has found varied applications, especially in stimulating erythropoiesis in anemia due to chronic conditions like renal failure, myelodysplasia, infections like HIV, in prematurity, and in reducing peri-operative blood transfusions. The discovery of erythropoietin receptor (EPO-R) and its presence in non-erythroid cells has led to several areas of research. Various types of rhEPO are commercially available today with different dosage schedules and modes of delivery. Their efficacy in stimulating erythropoiesis is dose dependent and differs according to the patient's disease and nutritional status. EPO should be used carefully according to guidelines as unsolicited use can result in serious adverse effects. Because of its capacity to improve oxygenation, it has been abused by athletes participating in endurance sports and detecting this has proved to be a challenge.

The effect of erythropoietin on anastomotic healing of irradiated rats

AIM

The aim of the present study is to evaluate the possible protective effects of erythropoietin (EPO) on anastomotic wound healing after preoperative radiotherapy according to its pleiotropic mechanism of action.

METHODS

Thirty-two male Wistar albino rats were randomized into four groups containing eight rats each: ANAS group, standard resection plus anastomosis; RT+ANAS group, radiation plus standard resection plus anastomosis; ANAS+EPO group, standard resection plus anastomosis plus EPO; RT+ANAS+EPO, radiation plus standard resection plus anastomosis plus EPO. All animals were sacrificed by cardiac puncture, and anastomotic healing was measured by bursting pressure, hydroxyproline (OHP) levels, myeloperoxidase (MPO) activity and histopathological evaluations. Malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-α), and matrix metalloproteinase-9 (MMP-9) were also measured in serum specimens.

RESULTS

OHP levels in the RT+ANAS + EPO group were significantly increased compared with other groups (p < .05). In contrast, MPO activity in the RT+ANAS+EPO group was significantly decreased compared with other groups (p < .05). Serum MDA levels were found to be decreased in the ANAS+EPO and RT+ANAS+EPO groups (p < .05). Group comparisons demonstrated that bursting pressure was significantly higher in EPO treated rats (p < .05). The histopathology results revealed that EPO treatment improves anastomotic wound healing though decreased necrosis and inflammatory cell infiltration and increased fibroblast activity.

CONCLUSION

The findings of the present study indicate that EPO contributes to wound healing and the strength of colon anastomosis following radiation due to its antioxidant and anti-inflammatory effects, but further studies are needed to explore the significance of these effects.

Emerging technologies in the delivery of erythropoietin for therapeutics

Deciphering the function of proteins and their roles in signaling pathways is one of the main goals of biomedical research, especially from the perspective of uncovering pathways that may ultimately be exploited for therapeutic benefit. Over the last half century, a greatly expanded understanding of the biology of the glycoprotein hormone erythropoietin (Epo) has emerged from regulator of the circulating erythrocyte mass to a widely used therapeutic agent. Originally viewed as the renal hormone responsible for erythropoiesis, recent in vivo studies in animal models and clinical trials demonstrate that many other tissues locally produce Epo independent of its effects on red blood cell mass. Thus, not only its hematopoietic activity but also the recently discovered nonerythropoietic actions in addition to new drug delivery systems are being thoroughly investigated in order to fulfill the specific Epo release requirements for each therapeutic approach. The present review focuses on updating the information previously provided by similar reviews and recent experimental approaches are presented to describe the advances in Epo drug delivery achieved in the last few years and future perspectives.

Mechanism of cardioprotective effect of erythropoietin-induced preconditioning in rat heart

Objective:

The cardioprotective potential of human recombinant erythropoietin (alpha) (Epo) against ischemia-reperfusion-induced injury is well known. But, the underlying mechanisms are not well elucidated. The aim of this study was to characterize the mechanism involved in the cardioprotective effect of Epo-induced preconditioning in isolated rat heart.

Materials and Methods:

The heart was mounted on a Langendorff apparatus. After 10 min of stabilization, four cycles of ischemic preconditioning (IPC) were given followed by 30 min of global ischemia and 120 min of reperfusion. Epo preconditioning was induced by four cycles of 5-min perfusion of K-H solution containing Epo (1.0 U/ml) followed by 5 min perfusion with K-H solution. Myocardial infarct size was estimated macroscopically using the triphenyltetrazolium chloride staining technique. The extent of myocardial injury was measured by release of lactate dehydrogenase and creatine kinase-MB in the coronary effluent.

Results:

The present study demonstrates that Epo preconditioning was almost as effective as IPC. Administration of Wortmannin (100 nM), a PI-3K inhibitor, or Chelerythrine (1 µM), a protein kinase-C (PKC) inhibitor, or AG490 (5 µM), a JAK-2 inhibitor, significantly attenuated the cardioprotective effects of Epo-induced preconditioning.

Conclusion:

Our result suggest that the cardioprotective potential of Epo-induced preconditioning in isolated rat heart was due to an interplay of the JAK-2, PI-3K and PKC pathways. Inhibition of any one of the three pathways was sufficient to block the cardioprotective effect of Epo-induced preconditioning in isolated rat heart.

Apoptosis during CABG surgery with the use of cardiopulmonary bypass is prominent in ventricular but not in atrial myocardium

Objectives. We aimed to compare the rate of apoptosis after cardiopulmonary bypass (CPB) and cardioplegic arrest during coronary artery bypass grafting (CABG) surgery between atrial and ventricular tissue.Methods. During CABG surgery with CPB and cardioplegic arrest, sequential biopsies were taken from the right atrial appendage and left ventricular anterior wall before CPB and after aortic cross clamp release. Change in number of apoptotic cells and biochemical markers of myocardial ischaemia and renal dysfunction were assessed.Results. CPB was associated with a transient small, but significant increase in CK (1091+/-374%), CK-MB (128+/-38%), troponin-T (102+/-13%) and NT-proBNP (1308+/-372%) levels (all: p<0.05). A higher number of apoptotic cells as assessed by caspase-3 staining was found in the ventricular biopsies taken after aortic cross clamp release compared with the biopsies taken before CPB (5.3+/-0.6 vs. 14.0+/-1.5 cells/microscopic field, p<0.01). The number of apoptotic cells in the atrial appendage was not altered during CPB. Correlation between the duration of aortic cross clamp time and the change in caspase-3 positive cells in the left ventricular wall was of borderline significance (r of 0.58, p=0.08). Similar results were obtained from TUNEL staining for apoptosis.Conclusion. CABG surgery with CPB and cardioplegic arrest is associated with an elevated rate of apoptosis in ventricular but not in atrial myocardial tissue. Ventricular tissue may be more sensitive to detect changes than atrial tissue, and may be more useful to investigate the protective effects of therapeutic intervention. (Neth Heart J 2010;18:236-42.).

Platelets alter gene expression profile in human brain endothelial cells in an in vitro model of cerebral malaria

Platelet adhesion to the brain microvasculature has been associated with cerebral malaria (CM) in humans, suggesting that platelets play a role in the pathogenesis of this syndrome. In vitro co-cultures have shown that platelets can act as a bridge between Plasmodium falciparum-infected red blood cells (pRBC) and human brain microvascular endothelial cells (HBEC) and potentiate HBEC apoptosis. Using cDNA microarray technology, we analyzed transcriptional changes of HBEC in response to platelets in the presence or the absence of tumor necrosis factor (TNF) and pRBC, which have been reported to alter gene expression in endothelial cells. Using a rigorous statistical approach with multiple test corrections, we showed a significant effect of platelets on gene expression in HBEC. We also detected a strong effect of TNF, whereas there was no transcriptional change induced specifically by pRBC. Nevertheless, a global ANOVA and a two-way ANOVA suggested that pRBC acted in interaction with platelets and TNF to alter gene expression in HBEC. The expression of selected genes was validated by RT-qPCR. The analysis of gene functional annotation indicated that platelets induce the expression of genes involved in inflammation and apoptosis, such as genes involved in chemokine-, TREM1-, cytokine-, IL10-, TGFβ-, death-receptor-, and apoptosis-signaling. Overall, our results support the hypothesis that platelets play a pathogenic role in CM.

Intravenous erythropoietin in patients with ST-segment elevation myocardial infarction: REVEAL: a randomized controlled trial

CONTEXT

Acute ST-segment elevation myocardial infarction (STEMI) is a leading cause of morbidity and mortality. In experimental models of MI, erythropoietin reduces infarct size and improves left ventricular (LV) function.

OBJECTIVE

To evaluate the safety and efficacy of a single intravenous bolus of epoetin alfa in patients with STEMI.

DESIGN, SETTING, AND PATIENTS

A prospective, randomized, double-blind, placebo-controlled trial with a dose-escalation safety phase and a single dose (60,000 U of epoetin alfa) efficacy phase; the Reduction of Infarct Expansion and Ventricular Remodeling With Erythropoietin After Large Myocardial Infarction (REVEAL) trial was conducted at 28 US sites between October 2006 and February 2010, and included 222 patients with STEMI who underwent successful percutaneous coronary intervention (PCI) as a primary or rescue reperfusion strategy.

INTERVENTION

Participants were randomly assigned to treatment with intravenous epoetin alfa or matching saline placebo administered within 4 hours of reperfusion.

MAIN OUTCOME MEASURE

Infarct size, expressed as percentage of LV mass, assessed by cardiac magnetic resonance (CMR) imaging performed 2 to 6 days after study medication administration (first CMR) and again 12 ± 2 weeks later (second CMR).

RESULTS

In the efficacy cohort, the infarct size did not differ between groups on either the first CMR scan (n = 136; 15.8% LV mass [95% confidence interval {CI}, 13.3-18.2% LV mass] for the epoetin alfa group vs 15.0% LV mass [95% CI, 12.6-17.3% LV mass] for the placebo group; P = .67) or on the second CMR scan (n = 124; 10.6% LV mass [95% CI, 8.4-12.8% LV mass] vs 10.4% LV mass [95% CI, 8.5-12.3% LV mass], respectively; P = .89). In a prespecified analysis of patients aged 70 years or older (n = 21), the mean infarct size within the first week (first CMR) was larger in the epoetin alfa group (19.9% LV mass; 95% CI, 14.0-25.7% LV mass) than in the placebo group (11.7% LV mass; 95% CI, 7.2-16.1% LV mass) (P = .03). In the safety cohort, of the 125 patients who received epoetin alfa, the composite outcome of death, MI, stroke, or stent thrombosis occurred in 5 (4.0%; 95% CI, 1.31%-9.09%) but in none of the 97 who received placebo (P = .04).

CONCLUSIONS

In patients with STEMI who had successful reperfusion with primary or rescue PCI, a single intravenous bolus of epoetin alfa within 4 hours of PCI did not reduce infarct size and was associated with higher rates of adverse cardiovascular events. Subgroup analyses raised concerns about an increase in infarct size among older patients.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00378352.

Erythropoietin: a hormone with multiple functions

Erythropoietin (EPO), the main hemopoietic hormone synthesized by the kidney as well as by the liver in fetal life, is implicated in mammalian erythropoiesis. Production and secretion of EPO and the expression of its receptor (EPO-R) are regulated by tissue oxygenation. EPO and EPO-R, expressed in several tissues, exert pleiotropic activities and have different effects on nonhemopoietic cells. EPO is a cytokine with antiapoptotic activity and plays a potential neuroprotective and cardioprotective role against ischemia. EPO is also involved in angiogenesis, neurogenesis, and the immune response. EPO can prevent metabolic alterations, neuronal and vascular degeneration, and inflammatory cell activation. Consequently, EPO may be of therapeutic use for a variety of disorders. Many tumors express EPO and/or EPO-R, but the action of EPO on tumor cells remains controversial. It has been suggested that EPO promotes the proliferation and survival of cancer cells expressing EPO-R. On the other hand, other reports have concluded that EPO-R plays no role in tumor progression. This review provides a detailed insight into the nonhemopoietic role of EPO and its mechanism(s) of action which may lead to a better understanding of its potential therapeutic value in diverse clinical settings.

Erythropoietin in stroke: quo vadis

IMPORTANCE OF THE FIELD

Recombinant erythropoietin (rEPO) failed in a recent clinical study to protect from damages induced by ischemic stroke. The lack of acute treatments in ischemic stroke and the promising outcome in numerous preclinical studies in vivo demands a more critical evaluation of the future use of EPO as an acute treatment.

AREAS COVERED IN THIS REVIEW

The current use and administration of rhEPO and its analogs in animal models and the future use of this cytokine in the treatment of ischemic stroke.

WHAT THE READER WILL GAIN

In this review the potential reasons for the failure of EPO in the clinical trial are analysed and whether the preclinical trials sufficiently evaluated the true potential of recombinant EPO and its analogs is assessed. Alternative methods for administration of EPO to enhance its potential as a neuroprotective drug in ischemic stroke are discussed.

TAKE HOME MESSAGE

Failure in clinical trial does not necessarily indicate the lack of therapeutic potential of EPO. This review encourages further investigation of the true potential of EPO as a candidate drug for the treatment of ischemic stroke by improved preclinical experimental design and utilization of alternative administration methods.

[Anemia in the elderly]

Anemia is a common disorder in the elderly and is associated with increased morbidity and mortality. In elderly subjects, in whom anemia is highly prevalent, there are several aspects, such as a hemoglobin at a level which should concern us limit, or identifying its causes, that are not easy to establish. This review focuses on knowing what is considered to be normal hemoglobin levels in adults and the common causes and potential consequences of anemia in elderly patients. It provides a diagnostic algorithm and an approach to treatment that addresses new treatments such as parenteral iron drugs and erythropoiesis-stimulating agents.

Bench to bedside: A role for erythropoietin in sepsis

Sepsis is the systemic inflammatory response to infection and can result in multiple organ dysfunction syndrome with associated high mortality, morbidity and health costs. Erythropoietin is a well-established treatment for the anaemia of renal failure due to its anti-apoptotic effects on red blood cells and their precursors. The extra-haemopoietic actions of erythropoietin include vasopressor, anti-apoptotic, cytoprotective and immunomodulating actions, all of which could prove beneficial in sepsis. Attenuation of organ dysfunction has been shown in several animal models and its vasopressor effects have been well characterised in laboratory and clinical settings. Clinical trials of erythropoietin in single organ disorders have suggested promising cytoprotective effects, and while no randomised trials have been performed in patients with sepsis, good quality data exist from studies on anaemia in critically ill patients, giving useful information of its pharmacokinetics and potential for harm. An observational cohort study examining the microvascular effects of erythropoietin is underway and the evidence would support further phase II and III clinical trials examining this molecule as an adjunctive treatment in sepsis.

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.

Erythropoiesis-stimulating agents in anemia: use and misuse

Erythropoiesis-stimulating agents (ESAs) have been in use for 2 decades. After the initial introduction for their use in anemia of end-stage renal disease, indications for the use of ESAs have widened to anemia of predialysis chronic kidney disease, cancer chemotherapy, HIV disease and orthopedic surgery. Along with the considerable benefits associated with the use of ESAs, adverse events have become apparent, in large part from overcorrection of the anemia. Data from recent studies have prompted several FDA warnings imposing the health provider to follow stringent criteria for the use of ESAs; these include close follow-up of patients, along with use of specific laboratory tests and criteria for dosing. Although adverse effects may partly relate to misuse, when appropriately administered, ESAs are useful agents in the medication armamentarium in the treatment of certain forms of anemia, with potential to improve outcomes and quality of life in some anemic individuals.

Oxidative stress: Biomarkers and novel therapeutic pathways

Oxidative stress significantly impacts multiple cellular pathways that can lead to the initiation and progression of varied disorders throughout the body. It therefore becomes imperative to elucidate the components and function of novel therapeutic strategies against oxidative stress to further clinical diagnosis and care. In particular, both the growth factor and cytokine erythropoietin (EPO) and members of the mammalian forkhead transcription factors of the O class (FoxOs) may offer the greatest promise for new treatment regimens since these agents and the cellular pathways they oversee cover a range of critical functions that directly influence progenitor cell development, cell survival and degeneration, metabolism, immune function, and cancer cell invasion. Furthermore, both EPO and FoxOs function not only as therapeutic targets, but also as biomarkers of disease onset and progression, since their cellular pathways are closely linked and overlap with several unique signal transduction pathways. However, biological outcome with EPO and FoxOs may sometimes be both unexpected and undesirable that can raise caution for these agents and warrant further investigations. Here we present the exciting as well as complicated role EPO and FoxOs possess to uncover the benefits as well as the risks of these agents for cell biology and clinical care in processes that range from stem cell development to uncontrolled cellular proliferation.

Neuroprotection in the newborn infant

Neonatal brain injury is an important cause of death and disability, with pathways of oxidant stress, inflammation, and excitotoxicity that lead to damage that progresses over a long period of time. Therapies have classically targeted individual pathways during early phases of injury, but more recent therapies such as growth factors may also enhance cell proliferation, differentiation, and migration over time. More recent evidence suggests combined therapy may optimize repair, decreasing cell injury while increasing newly born cells.

Erythropoietin, forkhead proteins, and oxidative injury: biomarkers and biology

Oxidative stress significantly impacts multiple cellular pathways that can lead to the initiation and progression of varied disorders throughout the body. It therefore becomes imperative to elucidate the components and function of novel therapeutic strategies against oxidative stress to further clinical diagnosis and care. In particular, both the growth factor and cytokine erythropoietin (EPO), and members of the mammalian forkhead transcription factors of the O class (FoxOs), may offer the greatest promise for new treatment regimens, since these agents and the cellular pathways they oversee cover a range of critical functions that directly influence progenitor cell development, cell survival and degeneration, metabolism, immune function, and cancer cell invasion. Furthermore, both EPO and FoxOs function not only as therapeutic targets, but also as biomarkers of disease onset and progression, since their cellular pathways are closely linked and overlap with several unique signal transduction pathways. Yet, EPO and FoxOs may sometimes have unexpected and undesirable effects that can raise caution for these agents and warrant further investigations. Here we present the exciting as well as the complex role that EPO and FoxOs possess to uncover the benefits as well as the risks of these agents for cell biology and clinical care in processes that range from stem cell development to uncontrolled cellular proliferation.

The vitamin nicotinamide: translating nutrition into clinical care

Nicotinamide, the amide form of vitamin B(3) (niacin), is changed to its mononucleotide compound with the enzyme nicotinic acide/nicotinamide adenylyltransferase, and participates in the cellular energy metabolism that directly impacts normal physiology. However, nicotinamide also influences oxidative stress and modulates multiple pathways tied to both cellular survival and death. During disorders that include immune system dysfunction, diabetes, and aging-related diseases, nicotinamide is a robust cytoprotectant that blocks cellular inflammatory cell activation, early apoptotic phosphatidylserine exposure, and late nuclear DNA degradation. Nicotinamide relies upon unique cellular pathways that involve forkhead transcription factors, sirtuins, protein kinase B (Akt), Bad, caspases, and poly (ADP-ribose) polymerase that may offer a fine line with determining cellular longevity, cell survival, and unwanted cancer progression. If one is cognizant of the these considerations, it becomes evident that nicotinamide holds great potential for multiple disease entities, but the development of new therapeutic strategies rests heavily upon the elucidation of the novel cellular pathways that nicotinamide closely governs.

Erythropoietin sustains cognitive function and brain volume after neonatal stroke

Neonatal stroke leads to mortality and severe morbidity, but there currently is no effective treatment. Erythropoietin (EPO) promotes cytoprotection and neurogenesis in the short term following brain injury; however, long-term cognitive outcomes and optimal dosing regimens have not been clarified. We performed middle cerebral artery occlusion in postnatal day 10 rats, which were treated with either a single dose of EPO (5 U/g, i.p.) immediately upon reperfusion, or 3 doses of EPO (1 U/g, i.p. each) at 0 h, 24 h, and 7 days after injury. At 3 months after injury, rats treated with 3 doses of EPO did not differ from shams in the Morris water maze, and generally performed better than either rats treated with a single dose or vehicle-treated injured rats. These multiple-dose-treated rats also had increases in hemispheric volume and its subregions. These results suggest that additional, later doses of EPO may be required for cell repair, proliferation, and long-term incorporation into neural networks after neonatal brain injury.

Downregulation of cell survival signalling pathways and increased cell damage in hydrogen peroxide-treated human renal proximal tubular cells by alpha-erythropoietin

OBJECTIVE

Erythropoietin has been shown to have a protective effect in certain models of ischaemia-reperfusion, and in some cases the protection has been correlated with activation of signalling pathways known to play a role in cell survival and proliferation. We have studied whether erythropoietin would overcome direct toxic effects of hydrogen peroxide (H(2)O(2)) treatment to human renal proximal tubular (HK-2) cells.

MATERIALS AND METHODS

HK-2 cells were incubated with H(2)O(2) (2 mm) for 2 h with or without erythropoietin at concentrations of 100 and 400 U/ml, and cell viability/proliferation was assessed by chemical reduction of MTT. Changes in phosphorylation state of the kinases Akt, glycogen synthase kinase-3beta (GSK-3beta), mammalian target of rapamycin (mTOR) and extracellular signal-regulated kinase 1 and 2 (ERK1/ERK2) were also analysed.

RESULTS

Cells incubated with H(2)O(2) alone showed a significant decrease in viability, which did not significantly change by addition of erythropoietin at concentration of 100 U/ml, but was further reduced when concentration of erythropoietin was increased to 400 U/ml. Phosphorylation state of the kinases Akt, GSK-3beta, mTOR and ERK1/ERK2 of H(2)O(2)-treated HK-2 cells was slightly altered in the presence of erythropoietin at concentration of 100 U/ml, but was significantly less in the presence of erythropoietin at a concentration of 400 U/ml. Phosphorylation of forkhead transcription factor FKHRL1 was diminished in cells incubated with H(2)O(2) and erythropoietin at a concentration of 400 U/ml.

CONCLUSIONS

Erythropoietin, at high concentrations, may significantly increase cellular damage in HK-2 cells subjected to oxidative stress, which may be due in part to decrease in activation of important signalling pathways involved in cell survival and/or cell proliferation.

Erythropoietin increases the motility of human bone marrow-multipotent stromal cells (hBM-MSCs) and enhances the production of neurotrophic factors from hBM-MSCs

Cell therapy has been extensively studied as an approach to repair damage in nervous system diseases. Multipotent stromal cells [MSCs] are well known to have neuroprotective effects and neural differentiation potential. The ability to induce migration of MSCs near nervous system damage via direct transplantation or via intravenous injections and increase the secretion of neurotrophic factors from MSCs might improve our ability to repair damage to the nervous system through cell therapy. In the present study, we investigated whether recombinant human erythropoietin [rhEPO], known to have a hematopoietic effect, could increase the motility of human bone marrow [hBM]-MSCs and enhance production of neurotrophic factors from hBM-MSCs. Based on the results of our MTT assay, trypan blue staining, and bromodeoxyuridine ELISA, rhEPO treatment increases the viability of MSCs but not their proliferation. With a migration assay kit, we demonstrated that the motility of hBM-MSCs was enhanced in rhEPO-treated cells. Immunoblotting assays revealed increased expression of phospho-Akt, phospho-GSK-3beta, phospho-extracellular signal-regulated kinase (ERK), beta PAK-interacting exchange factor (PIX), CXCR4, phospho tyrosine kinase B (TrkB), and vascular endothelial growth factor receptor-2 [VEGFR-2] in rhEPO-treated cells. Reverse transcription-polymerase chain reaction and gelatin zymography demonstrated that rhEPO treatment induces MMP-2 mRNA level and activity. In the studies using ELISAs, we found that rhEPO could increase levels of stromal cell-derived factor-1alpha, VEGF, and brain-derived neurotrophic factors. These findings suggest that rhEPO can increase the viability and motility of hBM-MSCs by affecting various intracellular signals including Akt, ERK, beta-PIX, CXCR4, TrkB, VEGFR-2, and MMP-2 and can enhance the production of neurotrophic factors from hBM-MSCs.

Erythropoietin augments the efficacy of therapeutic angiogenesis induced by allogenic bone marrow stromal cells in a rat model of limb ischemia

Transplantation of adult marrow stromal cells (MSCs) has been developed as a new method of treating severe ischemia diseases by therapeutic angiogenesis. Erythropoietin (EPO) is capable of inducing angiogenesis and inhibiting MSCs apoptosis. The effect of EPO on the therapeutic potency of MSCs transplantation in a rat model of limb ischemia was investigated in the current study. The results indicate that the combined treatment with MSC transplantation and EPO infusion is superior to MSC transplantation alone in the treatment of limb ischemia. MSCs transplantation and EPO infusion could enhance the angiogenic effect of each other to achieve a better therapeutic effect. This combination therapy may become a more effective approach for ischemia diseases of the limbs.

The association of red blood cell counts with endothelin-1 in African and Caucasian women

The literature shows an increase in endothelin-1 with increased levels of erythrocytes. There are also indications that inflammation and elevated endothelin-1 levels interact with erythropoiesis. In this study, the association of erythrocytes and endothelin-1 in women of different ethnicities was investigated. Blood pressure, vascular resistance, and C-reactive protein (P = 0.09) were significantly higher in the African women (n = 102) compared to the Caucasian women (n = 115), while arterial compliance was significantly lower in the African women with no significant differences for endothelin-1. In single, partial, and multiple regression analyses, there was a significant positive correlation between the red blood cell count and log endothelin-1 in the Caucasians while in the Africans there was a weak negative correlation. This is an indication that endothelin-1 might interfere with erythrocyte production in Africans with higher levels of inflammation.

Retinal vascular repair and neovascularization are not dependent on CX3CR1 signaling in a model of ischemic retinopathy

Proliferative retinal neovascularization occurring in response to ischemia is a common mechanism underlying many retinal diseases. In recent studies, retinal microglia have been shown to influence pathological neovascularization, likely through an exchange of cellular signals with associated vascular elements. CX3CR1 is a chemokine receptor located specifically on microglia; its ligand, CX3CL1 (also known as fractalkine or neurotactin) displays pro-angiogenic activity both in in vivo and in vitro. Discovering the regulatory role, if any, that CX3CR1 signaling may have in ischemic retinopathy will shed light on the molecular nature of microglial-vascular interactions and clarify potential targets for future therapy. In this study, we examined this question by inducing and comparing ischemic vascular changes in transgenic mice in which CX3CR1 signaling is either preserved or ablated. Using a well-known oxygen-induced retinopathy (OIR) model, we induced ischemic retinopathy in transgenic mice in which the gene for CX3CR1 has been replaced by green fluorescent protein (GFP) and their wild type controls. CX3CR1(+/+), CX3CR1(+/GFP), and CX3CR1(GFP/GFP) transgenic mice were exposed to 75% oxygen for 5 days starting from postnatal day (P) 7, and then transferred back to room air. At P12 and P17, the extents of vascular repair and neovascularization, and associated changes in retinal microglia distribution, were quantified and compared between mice of different genotypes. Neuronal loss in the retina following ischemia was also evaluated in paraffin sections. Our results show that: (1) CX3CR1 signaling is not required for normal vascular, microglial, and neuronal development in the retina in the first postnatal week, (2) the processes of retinal vascular repair and neovascularization following ischemia occur similarly with and without CX3CR1 signaling, (3) microglia redistribution in the retina and their association with vascular elements occurring concurrently is independent of CX3CR1, and (4) CX3CR1 does not influence the extent of neuronal cell loss in the retina following ischemia. Taken together, our findings indicate that the regulatory signals exchanged between microglia and vascular elements in the ischemic retinopathy animal model are unlikely to involve CX3CR1. These results have implications on therapeutic approaches to, pathological neovascularization involving the modulation of chemokine signaling in general, and the regulation of CX3CR1 signaling specifically.

Erythropoietin with retrobulbar administration protects retinal ganglion cells from acute elevated intraocular pressure in rats

OBJECTIVE

The aim of this study was to clarify whether erythropoietin (EPO) with a retrobulbar administration could protect retinal ganglion cells (RGCs) from acute elevated intraocular pressure (IOP).

METHODS

The anterior chamber of the right eye was cannulated, and the IOP was raised to 70 mm Hg for a duration of up to 60 min. One thousand (1000) units of recombinant erythropoietin (rhEPO) or vehicle solution was administered a retrobulbar injection immediately after the onset of the acute elevated IOP. After 1 week, RGCs were labeled with a commercially available retrograde tracer applied to the superior colliculi. Densities of surviving RGCs were estimated by counting retrograde-tracer-labeled cells in whole-mounted retinas. The ultrastructural changes of RGCs were observed by transmission electron microscope. Immunocytochemistry was used to detect EPO and erythropoietin receptor (EPOR) expression in the RGCs layer.

RESULTS

The acute elevated IOP could result in the loss of RGCs. The number of surviving RGCs per square millimeter in the eyes of the acute elevated IOP + rhEPO retrobulbar injection group was significantly higher than that in the eyes of the acute elevated IOP and acute elevated IOP + vehicle solution retrobulbar injection groups (P < 0.05). The number of the organelles in the RGCs plasm decreased, but some intact mitochondrian still existed in the RGCs plasm in the eyes of the acute elevated IOP + rhEPO retrobulbar injection group. The densities of EPO and EPOR expression of the RGCs layer in the eyes of the acute elevated IOP + rhEPO retrobulbar injection group were significantly higher than that in the eyes of the acute elevated IOP and acute elevated IOP + vehicle solution retrobulbar injection groups (P < 0.01).

CONCLUSION

EPO with a retrobulbar administration could protect RGCs from acute elevated IOP.