Erythropoietin effect on sensorimotor recovery after contusive spinal cord injury: an electrophysiological study in rats

Therapeutic strategies that modulate the acute phase of secondary spinal cord injury scarring and inflammation and improve injury outcomes

INTRODUCTION

The acute phase of secondary spinal cord injury (SCI) is a crucial therapeutic window to mitigate ongoing damage and promote tissue repair. The present systematic review critically evaluates the efficacy and safety of current management modalities for this phase, identifying gaps in knowledge and providing insights for future research directions.

METHODS

In December 2024, PubMed, Web of Science, Google Scholar, and Embase were accessed with no time constraints. All the clinical studies investigating the pharmacological management of secondary SCI were accessed.

RESULTS

Data from 3017 patients (385 women) were collected. The mean length of the follow-up was 6 ± 3.4 months, and the mean age of the patients was 43.3 ± 10.3 years.

CONCLUSION

Erythropoietin (EPO) improves motor function, reduces impairment in secondary spinal cord injury, modulates antioxidation and neurogenesis, and minimizes apoptosis and inflammation. Although commonly administered, methylprednisolone shows uncertain efficacy. The rho-GTPases inhibitor VX-210 and levetiracetam did not demonstrate effectiveness in treatment. Monosialotetrahexosylganglioside Sodium Salt (GM-1) and riluzole are associated with favorable neurological outcomes. Granulocyte Colony-Stimulating Factor (G-CSF) and Hepatocyte Growth Factor (HGF) offer improved motor scores with fewer side effects.

Erythropoietin to Treat Spinal Cord Injury: Evaluation of Different Doses and Magnitudes of Trauma in Rats

STUDY DESIGN

Experimental spinal cord lesion study.

OBJECTIVES

To evaluate the effects of erythropoietin at different doses on neural regeneration in rats undergoing spinal cord injury.

METHODS

Anesthetized Wistar rats were submitted to standardized spinal cord injury and randomized into eight groups, receiving different magnitudes of trauma and single or repeated doses of intraperitoneal erythropoietin (500 or 5000 IU/kg of body weight). We evaluated motor function using BBB scores and sensorimotor behavior by observing the rats walking on a horizontal ladder (at 2, 4, and 6 weeks) and performed histological analysis of the spinal cord after euthanasia. We compared the scores between groups using analysis of variance (ANOVA) and Bonferroni multiple comparisons.

RESULTS

The experiments were conducted with 10 animals per group (n = 80), none of which died or were excluded. BBB scores increased over time (meaning recovery) in all groups (P < 0.001 for all). From the fourth week, animals receiving lower trauma and higher erythropoietin doses had higher BBB scores than those receiving lower doses. The total number of steps and correct steps taken on the horizontal ladder increased, and slips decreased over time with treatment in all groups. Although the number of errors was different between moments (P < 0.001), it was not different between groups (P = 0.707). Rats receiving higher impact lesions had more spinal cord necrosis and worse recovery of neuronal fibers than the rest.

CONCLUSIONS

Animals receiving a higher dose of erythropoietin and suffering minor trauma showed better and faster neurological recovery. Repeating erythropoietin after a week showed no benefit.

Advancements in neuroregenerative and neuroprotective therapies for traumatic spinal cord injury

Traumatic spinal cord injuries (SCIs) continue to be a major healthcare concern, with a rising prevalence worldwide. In response to this growing medical challenge, considerable scientific attention has been devoted to developing neuroprotective and neuroregenerative strategies aimed at improving the prognosis and quality of life for individuals with SCIs. This comprehensive review aims to provide an up-to-date and thorough overview of the latest neuroregenerative and neuroprotective therapies currently under investigation. These strategies encompass a multifaceted approach that include neuropharmacological interventions, cell-based therapies, and other promising strategies such as biomaterial scaffolds and neuro-modulation therapies. In addition, the review discusses the importance of acute clinical management, including the role of hemodynamic management as well as timing and technical aspects of surgery as key factors mitigating the secondary injury following SCI. In conclusion, this review underscores the ongoing scientific efforts to enhance patient outcomes and quality of life, focusing on upcoming strategies for the management of traumatic SCI. Each section provides a working knowledge of the fundamental preclinical and patient trials relevant to clinicians while underscoring the pathophysiologic rationale for the therapies.

Erythropoietin alleviates astrocyte pyroptosis by targeting the miR-325-3p/Gsdmd axis in rat spinal cord injury

BACKGROUND

Neuroinflammation plays an important role in spinal cord injury (SCI), and an increasing number of studies have focused on the role of astrocytes in neuroinflammation. Pyroptosis is an inflammation-related form of programmed cell death, and neuroinflammation induced by astrocytes in the form of pyroptosis has been widely reported in many central nervous system diseases. Recent studies have found that erythropoietin has significant anti-inflammatory and neuroprotective effects in SCI; however, it has not been reported whether erythropoietin can reduce neuroinflammation by inhibiting neural cell pyroptosis in SCI.

METHODS

A GEO dataset (GSE153720) was used to analyse the expression of pyroptosis-related genes in sham astrocytes and astrocytes 7 days, 1 month and 3 months after SCI. TargetScan and miRDB databases were used to predict the miRNA that could bind to the 3'UTR of rat Gsdmd. Primary rat spinal astrocytes were used for in vitro experiments, and the modified version of Allen's method was used to establish the rat SCI model. Western blotting, quantitative real-time polymerase chain reaction, flow cytometry, immunofluorescence, lactate dehydrogenase release assay and propidium iodide staining were used to detect the pyroptosis phenotype. A dual luciferase reporter gene assay was used to verify that miR-325-3p can bind to the 3'UTR of Gsdmd.

RESULTS

We found that pyroptosis-related genes mediated by the canonical NLRP3 inflammasome were highly expressed in astrocytes in an SCI animal model by bioinformatic analysis. We also observed that erythropoietin could reduce astrocyte pyroptosis in vivo and in vitro. In addition, we predicted miRNAs that regulate Gsdmd, the pyroptosis executor, and verified that erythropoietin inhibits astrocyte pyroptosis in SCI through the miR-325-3p/Gsdmd axis.

CONCLUSIONS

We demonstrated that erythropoietin can inhibit astrocyte pyroptosis through the miR-325-3p/Gsdmd axis. This study is expected to provide a new mechanism for erythropoietin in the treatment of SCI and a more reliable theoretical basis for clinical research.

Neurotrophic Factors as Regenerative Therapy for Neurodegenerative Diseases: Current Status, Challenges and Future Perspectives

Neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), multiple sclerosis (MS), spinal cord injury (SCI), and amyotrophic lateral sclerosis (ALS), are characterized by acute or chronic progressive loss of one or several neuronal subtypes. However, despite their increasing prevalence, little progress has been made in successfully treating these diseases. Research has recently focused on neurotrophic factors (NTFs) as potential regenerative therapy for neurodegenerative diseases. Here, we discuss the current state of knowledge, challenges, and future perspectives of NTFs with a direct regenerative effect in chronic inflammatory and degenerative disorders. Various systems for delivery of NTFs, such as stem and immune cells, viral vectors, and biomaterials, have been applied to deliver exogenous NTFs to the central nervous system, with promising results. The challenges that currently need to be overcome include the amount of NTFs delivered, the invasiveness of the delivery route, the blood-brain barrier permeability, and the occurrence of side effects. Nevertheless, it is important to continue research and develop standards for clinical applications. In addition to the use of single NTFs, the complexity of chronic inflammatory and degenerative diseases may require combination therapies targeting multiple pathways or other possibilities using smaller molecules, such as NTF mimetics, for effective treatment.

Elucidating the Pivotal Neuroimmunomodulation of Stem Cells in Spinal Cord Injury Repair

Spinal cord injury (SCI) is a distressing incident with abrupt onset of the motor as well as sensory dysfunction, and most often, the injury occurs as result of high-energy or velocity accidents as well as contact sports and falls in the elderly. The key challenges associated with nerve repair are the lack of self-repair as well as neurotrophic factors and primary and secondary neuronal apoptosis, as well as factors that prevent the regeneration of axons locally. Neurons that survive the initial traumatic damage may be lost due to pathogenic activities like neuroinflammation and apoptosis. Implanted stem cells are capable of differentiating into neural cells that replace injured cells as well as offer local neurotrophic factors that aid neuroprotection, immunomodulation, axonal sprouting, axonal regeneration, and remyelination. At the microenvironment of SCI, stem cells are capable of producing growth factors like brain-derived neurotrophic factor and nerve growth factor which triggers neuronal survival as well as axonal regrowth. Although stem cells have proven to be of therapeutic value in SCI, the major disadvantage of some of the cell types is the risk for tumorigenicity due to the contamination of undifferentiated cells prior to transplantation. Local administration of stem cells via either direct cellular injection into the spinal cord parenchyma or intrathecal administration into the subarachnoid space is currently the best transplantation modality for stem cells during SCI.

Motor, sensitive, and vegetative recovery in rats with compressive spinal-cord injury after combined treatment with erythropoietin and whole-body vibration

BACKGROUND

Physical therapy with whole body vibration (WBV) following compressive spinal cord injury (SCI) in rats restores density of perisomatic synapses, improves body weight support and leads to a better bladder function. The purpose of the study was to determine whether the combined treatment with WBV plus erythropoietin (EPO) would further improve motor, sensory and vegetative functions after SCI in rats.

METHODS

Severe compressive SCI at low thoracic level was followed by a single i.p. injection of 2,5μg (250 IU) human recombinant EPO. Physical therapy with WBV started on 14th day after injury and continued over a 12-week post injury period. Locomotor recovery, sensitivity tests and urinary bladder scores were analysed at 1, 3, 6, 9, and 12 weeks after SCI. The closing morphological measurements included lesion volume and numbers of axons in the preserved perilesional neural tissue bridges (PNTB).

RESULTS

Assessment of motor performance sensitivity and bladder function revealed no significant effects of EPO when compared to the control treatments. EPO treatment neither reduced the lesion volume, nor increased the number of axons in PNTB.

CONCLUSIONS

The combination of WBV + EPO exerts no positive effects on hind limbs motor performance and bladder function after compressive SCI in rats.

Potential anti-inflammatory effect of erythropoietin in non-clinical studies in vivo: A systematic review

Erythropoietin (EPO) is a hypoxia-induced hormone produced in adult kidneys with erythropoietic and non-erythropoietic effects. In vivo studies represent an important role to comprehend the efficacy and safety in the early phase of repurposing drugs. The aim is to evaluate the potential anti-inflammatory effect of EPO observed in animal models of disease. Following PRISMA statements, electronic database Medline via PubMed platform was used to search articles with the research expression ((erythropoietin [MeSH Terms]) AND (inflammation [MeSH Terms]) AND (disease models, animal [MeSH Terms])). The inclusion criteria were original articles, studies where EPO was administered, studies where inflammation was studied and/or evaluated, non-clinical studies in vivo with rodents, and articles published in English. Thirty-six articles met the criteria for qualitative analysis. Exogenous EPO was used in models of sepsis, traumatic brain injury, and autoimmune neuritis, with an average of 3000 IU/Kg for single and multiple doses, using mice and rats. Biomarkers such as immune-related effectors, cytokines, reactive oxygen species, prostaglandins, and other biomarkers were assessed. EPO has been recognized as a multifunctional cytokine with anti-inflammatory properties, showing its significant effect both in acute and chronic models of inflammation. Further non-clinical studies are suggested for the enlightenment of anti-inflammatory mechanisms of EPO in lower doses, allowing us to understand the translational data for humans.

Novel approach to an early assessment of a patient's potential for neurological remission after acute spinal cord injury: Analysis of hemoglobin concentration dynamics

Context/objective: Examining hemoglobin (Hb) dynamics with regard to the potential of neurological remission in patients with traumatic spinal cord injury (TSCI).Design: Prospective Clinical Observational Study.Setting: BG Trauma Centre Ludwigshafen, Department of Paraplegiology, Rhineland-Palatinate, Germany.Methods: From 2011 to 2017 a total of 80 patients with acute spinal injury were enrolled and divided into three groups: initial neurological impairment either with (G1; n = 33) or without subsequent neurological remission (G0; n = 35) and vertebral fractures without initial neurological impairment as control group (C; n = 12). Blood samples were taken for 3 months at 11 time-points after injury. Analyses were performed using routine diagnostics.Outcome measures: Multiple logistic regression was used to determine the prognostic value of Hb regarding neurological remission respecting clinical covariates.Results: Data showed elevated mean Hb concentrations in G1 from the third day to 1 month compared to G0, Hb levels were significantly higher in G1 after 3 days (P = 0.03, G1 > G0). The final multiple logistic regression model based on this data predicting the presence of neurological remission resulted in an AUC (area under the curve) of 80.5% (CI: 67.8%-93.2%) in the ROC (receiver operating characteristic) analysis.Conclusion: Elevated Hb concentrations are associated with a higher likelihood of neurological remission. Elevated concentrations of Hb in G1 compared to G0 over time might be linked to both a better initial oxygen supply response and a decreased ECM (extracellular matrix) degradation highlighting the role of Hb as a valuable biomarker for neural regeneration after TSCI.

The effect of combination therapy with erythropoietin and methylprednisolone in patients with traumatic cervical spinal cord injury: a pilot randomized controlled trial

STUDY DESIGN

Pilot double-blinded randomized controlled trial.

OBJECTIVES

To investigate the additive effect of recombinant human erythropoietin (rhEPO) on functional outcome and disability in patients with traumatic cervical spinal cord injury (TCSCI).

SETTINGS

University-affiliated hospital in Mashhad, Iran.

METHODS

Patients with acute TCSCI admitted within 8 h after injury were randomly assigned to receive only methylprednisolone (M group) or rhEPO 500 IU/mL plus methylprednisolone (M + E group). All the patients underwent surgery within the next several days. Neurological function was assessed on admission, and at 6th and 12th months after the injury according to the sphincter function and American spinal cord injury association (ASIA) scale.

RESULTS

Overall, 54 patients (mean age: 39.7 ± 13.3 years) including 46 (85%) males were studied in two groups of 27. The likelihood of developing adverse neurological outcomes (ASIA impairment score of A compared to D or E) was not significantly different between the groups after 6 (OR = 0.39, 95% CI = 0.03-4.80, P = 0.46) and 12 months (OR = 0.83, 95% CI = 0.11-6.11, P = 0.86). The groups also showed no significant difference in 1-year mortality (OR = 0.83, 95% CI = 0.25-2.74, P = 0.76).

CONCLUSIONS

It is not clear whether combination therapy with erythropoietin compared to methylprednisolone alone improves neurological functions of patients with TCSCI. Our study provides interim data to guide future larger definitive trials.

Endocrine Therapy for the Functional Recovery of Spinal Cord Injury

Spinal cord injury (SCI) is a major cause of physical disability and leads to patient dissatisfaction with their quality of life. Patients with SCI usually exhibit severe clinical symptoms, including sensory and motor dysfunction below the injured levels, paraplegia, quadriplegia and urinary retention, which can exacerbate the substantial medical and social burdens. The major pathological change observed in SCI is inflammatory reaction, which induces demyelination, axonal degeneration, and the apoptosis and necrosis of neurons. Traditional medical treatments are mainly focused on the recovery of motor function and prevention of complications. To date, numerous studies have been conducted to explore the cellular and molecular mechanism of SCI and have proposed lots of effective treatments, but the clinical applications are still limited due to the complex pathogenesis and poor prognosis after SCI. Endocrine hormones are kinds of molecules that are synthesized by specialized endocrine organs and can participate in the regulation of multiple physiological activities, and their protective effects on several disorders have been widely discussed. In addition, many studies have identified that endocrine hormones can promote nerve regeneration and functional recovery in individuals with central nervous system diseases. Therefore, studies investigating the clinical applications of endocrine hormones as treatments for SCI are necessary. In this review, we described the neuroprotective roles of several endocrine hormones in SCI; endocrine hormone administration reduces cell death and promotes functional repair after SCI. We also proposed novel therapies for SCI.

Erythropoietin as a Neuroprotective Molecule: An Overview of Its Therapeutic Potential in Neurodegenerative Diseases

Erythropoietin (EPO) is a cytokine mainly induced in hypoxia conditions. Its major production site is the kidney. EPO primarily acts on the erythroid progenitor cells in the bone marrow. More and more studies are highlighting its secondary functions, with a crucial focus on its role in the central nervous system. Here, EPO may interact with up to four distinct isoforms of its receptor (erythropoietin receptor [EPOR]), activating different signaling cascades with roles in neuroprotection and neurogenesis. Indeed, the EPO/EPOR axis has been widely studied in the neurodegenerative diseases field. Its potential therapeutic effects have been evaluated in multiple disorders, such as Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, spinal cord injury, as well as brain ischemia, hypoxia, and hyperoxia. EPO is showing great promise by counteracting secondary neuroinflammatory processes, reactive oxygen species imbalance, and cell death in these diseases. Multiple studies have been performed both in vitro and in vivo, characterizing the mechanisms through which EPO exerts its neurotrophic action. In some cases, clinical trials involving EPO have been performed, highlighting its therapeutic potential. Together, all these works indicate the potential beneficial effects of EPO.

Intranasal erythropoietin ameliorates neurological function impairments and neural pathology in mice with chronic alcoholism by regulating autophagy‑related Nrf2 degradation

The neurological disorders and neural pathology brought about by chronic alcoholism are difficult to be reversed. Increasing evidence highlights the protective roles of erythropoietin (EPO) in neurodegenerative diseases and injuries of the central nervous system. In the present study, we investigated the therapeutic effects of EPO on the neurological function deficits and neural pathology caused by chronic alcoholism and the regulatory mechanisms. Using the canonical mouse model of chronic alcohol exposure designed to mimic the repeated cycles of heavy abuse typical of chronic alcoholism, it was found that EPO delivered via intranasal route effectively restored the alcohol-impaired motor cooperation in rotarod and beam walk tests, reversed alcoholic cognitive and emotional alterations in the novel location recognition task and open-filed test, and rescued alcohol-disrupted nervous conduction in the somatosensory-evoked potential (SSEP) test. Consistently, the intranasally administered EPO promoted the remyelination and synapse formation in chronic alcohol-affected neocortex and hippocampus as evidenced by immunofluorescence staining and transmission electron microscopy. Additionally, we discovered that the exogenous rhEPO, which entered the cerebrum through intranasal route, activated the erythropoietin receptor (EPOR) and the downstream ERKs and PI3K/AKT signaling, and suppressed autophagy-related degradation of nuclear factor, erythroid 2-like 2 (Nrf2). Furthermore, the intranasal EPO-exerted neuroprotection was almost abolished when the specific Nrf2 antagonist ATRA was administered intraperitoneally prior to intranasal EPO treatment. Collectively, our data demonstrated the repairing potential of EPO for the neurological disorders and neural pathology caused by chronic alcoholism, and identified the Nrf2 activity as the key mechanism mediating the protective effects of EPO.

Erythropoietin reduces nerve demyelination, neuropathic pain behavior and microglial MAPKs activation through erythropoietin receptors on Schwann cells in a rat model of peripheral neuropathy

Neuroprotective effects of erythropoietin (EPO) on peripheral nerve injury remain uncertain. This study investigated the efficacy of EPO in attenuating median nerve chronic constriction injury (CCI)-induced neuropathy. Animals received an intraneural injection of EPO at doses of 1,000, 3,000, or 5,000 units/kg 15 min before median nerve CCI. Afterwards, the behavioral and electrophysiological tests were conducted. Immunohistochemistry and immunoblotting were used for qualitative and quantitative analysis of microglial and mitogen-activated protein kinases (MAPKs), including p38, JNK, and ERK, activation. Enzyme-linked immunosorbent assay and microdialysis were applied to measure pro-inflammatory cytokine and glutamate responses, respectively. EPO pre-treatment dose-dependently ameliorated neuropathic pain behavior, decreased microglial and MAPKs activation, and diminished the release of pro-inflammatory cytokines and glutamate in the ipsilateral cuneate nucleus after CCI. Moreover, EPO pre-treatment preserved myelination of the injured median nerve on morphological investigation and suppressed injury-induced discharges. We also observed that EPO receptor (EPOR) expression was up-regulated in the injured nerve after CCI. Double immunofluorescence showed that EPOR was localized to Schwann cells. Furthermore, siRNA-mediated knockdown of EPOR expression eliminated the therapeutic effects of EPO on attenuating the microglial and MAPKs activation, pro-inflammatory cytokine responses, injury discharges, and neuropathic pain behavior in CCI rats. In conclusion, binding of EPO to its receptors on Schwann cells maintains myelin integrity and blocks ectopic discharges in the injured median nerve, that in the end contribute to attenuation of neuropathic pain via reducing glutamate release from primary afferents and inhibiting activation of microglial MAPKs and production of pro-inflammatory cytokines.

Regulation of Inflammatory Cytokines for Spinal Cord Injury Repair Through Local Delivery of Therapeutic Agents

The balance of inflammation is critical to the repair of spinal cord injury (SCI), which is one of the most devastating traumas in human beings. Inflammatory cytokines, the direct mediators of local inflammation, have differential influences on the repair of the injured spinal cord. Some inflammatory cytokines are demonstrated beneficial to spinal cord repair in SCI models, while some detrimental. Various animal researches have revealed that local delivery of therapeutic agents efficiently regulates inflammatory cytokines and promotes repair from SCI. Quite a few clinical studies have also shown the promotion of repair from SCI through regulation of inflammatory cytokines. However, local delivery of a single agent affects only a part of the inflammatory cytokines that need to be regulated. Meanwhile, different individuals have differential profiles of inflammatory cytokines. Therefore, future studies may aim to develop personalized strategies of locally delivered therapeutic agent cocktails for effective and precise regulation of inflammation, and substantial functional recovery from SCI.

EPO-releasing neural precursor cells promote axonal regeneration and recovery of function in spinal cord traumatic injury

Background:

Spinal cord injury (SCI) is a debilitating condition characterized by a complex of neurological dysfunctions ranging from loss of sensation to partial or complete limb paralysis. Recently, we reported that intravenous administration of neural precursors physiologically releasing erythropoietin (namely Er-NPCs) enhances functional recovery in animals following contusive spinal cord injury through the counteraction of secondary degeneration. Er-NPCs reached and accumulated at the lesion edges, where they survived throughout the prolonged period of observation and differentiated mostly into cholinergic neuron-like cells.

Objective:

The aim of this study was to investigate the potential reparative and regenerative properties of Er-NPCs in a mouse experimental model of traumatic spinal cord injury.

Methods and Results:

We report that Er-NPCs favoured the preservation of axonal myelin and strongly promoted the regrowth across the lesion site of monoaminergic and chatecolaminergic fibers that reached the distal portions of the injured cord. The use of an anterograde tracer transported by the regenerating axons allowed us to assess the extent of such a process. We show that axonal fluoro-ruby labelling was practically absent in saline-treated mice, while it resulted very significant in Er-NPCs transplanted animals.

Conclusion:

Our study shows that Er-NPCs promoted recovery of function after spinal cord injury, and that this is accompanied by preservation of myelination and strong re-innervation of the distal cord. Thus, regenerated axons may have contributed to the enhanced recovery of function after SCI.

Tolerability and efficacy of erythropoietin (EPO) treatment in traumatic spinal cord injury: a preliminary randomized comparative trial vs. methylprednisolone (MP)

The only available treatment of traumatic spinal cord injury (TSCI) is high-dose methylprednisolone (MP) administered acutely after injury. However, as the efficacy of MP is controversial, we assessed the superiority of erythropoietin (EPO) versus MP in improving clinical outcome of acute TSCI. Patients aged 18 to 65 years after C5-T12 injury, and grade A or B of the ASIA Impairment Scale (AIS), admitted within 8 h, hemodynamically stable, were randomized to MP according to the NASCIS III protocol or EPO iv (500 UI/kg, repeated at 24 and 48 h). Patients were assessed by an investigator blind to treatment assignment at baseline and at day 3, 7, 14, 30, 60 and 90. Primary end point: number of responders (reduction of at least one AIS grade). Secondary end points: treatment safety and the effects of drugs on a number of disability measures. Frequentistic and post hoc Bayesian analyses were performed. Eight patients were randomized to MP and 11 to EPO. Three patients (27.3 %) on EPO and no patients on MP reached the primary end point (p = 0.17). No significant differences were found for the other disability measures. No adverse events or serious adverse events were reported in both groups. The Bayesian analysis detected a 91.8 % chance of achieving higher success rates on the primary end point with EPO in the intention-to-treat population with a 95 % chance the difference between EPO and MP falling in the range (-0.10, 0.51) and a median value of 0.2. The results of Bayesian analysis favored the experimental treatment.

Erythropoietin action in stress response, tissue maintenance and metabolism

Erythropoietin (EPO) regulation of red blood cell production and its induction at reduced oxygen tension provides for the important erythropoietic response to ischemic stress. The cloning and production of recombinant human EPO has led to its clinical use in patients with anemia for two and half decades and has facilitated studies of EPO action. Reports of animal and cell models of ischemic stress in vitro and injury suggest potential EPO benefit beyond red blood cell production including vascular endothelial response to increase nitric oxide production, which facilitates oxygen delivery to brain, heart and other non-hematopoietic tissues. This review discusses these and other reports of EPO action beyond red blood cell production, including EPO response affecting metabolism and obesity in animal models. Observations of EPO activity in cell and animal model systems, including mice with tissue specific deletion of EPO receptor (EpoR), suggest the potential for EPO response in metabolism and disease.

Multi-modal assessment of long-term erythropoietin treatment after neonatal hypoxic-ischemic injury in rat brain

Erythropoietin (EPO) has been recognized as a neuroprotective agent. In animal models of neonatal brain injury, exogenous EPO has been shown to reduce lesion size, improve structure and function. Experimental studies have focused on short course treatment after injury. Timing, dose and length of treatment in preterm brain damage remain to be defined. We have evaluated the effects of high dose and long-term EPO treatment in hypoxic-ischemic (HI) injury in 3 days old (P3) rat pups using histopathology, magnetic resonance imaging (MRI) and spectroscopy (MRS) as well as functional assessment with somatosensory-evoked potentials (SEP). After HI, rat pups were assessed by MRI for initial damage and were randomized to receive EPO or vehicle. At the end of treatment period (P25) the size of resulting cortical damage and white matter (WM) microstructure integrity were assessed by MRI and cortical metabolism by MRS. Whisker elicited SEP were recorded to evaluate somatosensory function. Brains were collected for neuropathological assessment. The EPO treated animals did not show significant decrease of the HI induced cortical loss at P25. WM microstructure measured by diffusion tensor imaging was improved and SEP response in the injured cortex was recovered in the EPO treated animals compared to vehicle treated animals. In addition, the metabolic profile was less altered in the EPO group. Long-term treatment with high dose EPO after HI injury in the very immature rat brain induced recovery of WM microstructure and connectivity as well as somatosensory cortical function despite no effects on volume of cortical damage. This indicates that long-term high-dose EPO induces recovery of structural and functional connectivity despite persisting gross anatomical cortical alteration resulting from HI.