Erythropoietin protects from post-traumatic edema in the rat brain

Neuropharmacology in traumatic brain injury: from preclinical to clinical neuroprotection?

Traumatic brain injury (TBI) constitutes a major health problem worldwide and is a leading cause of death and disability in individuals, contributing to devastating socioeconomic consequences. Despite numerous promising pharmacological strategies reported as neuroprotective in preclinical studies, the translation to clinical trials always failed, albeit the great diversity of therapeutic targets evaluated. In this review, first, we described epidemiologic features, causes, and primary and secondary injuries of TBI. Second, we outlined the current literature on animal models of TBI, and we described their goals, their advantages and disadvantages according to the species used, the type of injury induced, and their clinical relevance. Third, we defined the concept of neuroprotection and discussed its evolution. We also identified the reasons that might explain the failure of clinical translation. Then, we reviewed post‐TBI neuroprotective treatments with a focus on the following pleiotropic drugs, considered “low hanging fruit” with high probability of success: glitazones, glibenclamide, statins, erythropoietin, and progesterone, that were largely tested and demonstrated efficient in preclinical models of TBI. Finally, our review stresses the need to establish a close cooperation between basic researchers and clinicians to ensure the best clinical translation for neuroprotective strategies for TBI.

Preparation and Evaluation of Recombinant Human Erythropoietin Loaded Tween 80-Albumin Nanoparticle for Traumatic Brain Injury Treatment

OBJECTIVE

Traumatic brain injury (TBI) is a serious health problem with few available treatment options. Rh-erythropoietin (rh-EPO) is a potential therapeutic drug for TBI, but it cannot cross the blood-brain barrier (BBB) directly. In this regard, a novel strategy to deliver rh-EPO for enhanced TBI treatment is via the development of Tween 80 modified albumin nanoparticles using electrostatic spray technology.

METHODS

The rh-EPO loaded Tween 80 modified albumin nanoparticles (rh-EPO-Tw-ABNPs) were prepared by electrostatic spray technology, while the process parameters were optimized via a single factor design. Investigation of physicochemical properties, bioactivity and stability of rh-EPO-Tw-ABNPs was carried out. The in vitro release and biocompatibility with nerve cells were also analyzed. The in vivo brain targeting efficiency, brain edema relieving effect and the expression of aquaporin 4 (AQP4) and glial fibrillary acidic protein (GFAP) in the brain were evaluated in TBI model rats.

RESULTS

The particle size of optimal rh-EPO-Tw-ABNPs was about 438 ± 45 nm, with a zeta potential of -25.42 ± 0.8 mv. The average drug loading ratio of rh-EPO-Tw-ABNPs was 21.3± 3.7 IU/mg with a relative bioactivity of 91.6 ± 4.1%. The in vitro release of rh-EPO from the nanoparticles was rather slow, while neither the blank Tw-ABNPs nor rh-EPO-Tw-ABNPs exhibited toxicity on the microglia cells. Furthermore, in vivo experiments indicated that the rh-EPO-Tw-ABNPs could enhance the distribution of EPO in the brain and relieve brain edema more effectively. Moreover, compared with an rh-EPO injection, the rh-EPO-Tw-ABNPs could increase the AQP4 level but reduced GFAP expression in the brain with more efficiency.

CONCLUSION

The rh-EPO-Tw-ABNPs could enhance the transport of rh-EPO into the brain with superior therapeutic effect for TBI.

Erythropoietin Does Not Alter Serum Profiles of Neuronal and Axonal Biomarkers After Traumatic Brain Injury: Findings From the Australian EPO-TBI Clinical Trial

OBJECTIVE

To determine profiles of serum ubiquitin carboxy-terminal hydrolase L1 and phosphorylated neurofilament heavy-chain, examine whether erythropoietin administration reduce their concentrations, and whether biomarkers discriminate between erythropoietin and placebo treatment groups.

DESIGN

Single-center, prospective observational study.

SETTING

A sub-study of the erythropoietin-traumatic brain injury clinical trial, conducted at the Alfred Hospital, Melbourne, Australia.

PATIENTS

Forty-four patients with moderate-to-severe traumatic brain injury.

INTERVENTIONS

Epoetin alfa 40,000 IU or 1 mL sodium chloride 0.9 as subcutaneous injection within 24 hours of traumatic brain injury.

MEASUREMENTS AND MAIN RESULTS

Ubiquitin carboxy-terminal hydrolase L1, phosphorylated neurofilament heavy-chain, and erythropoietin concentrations were measured in serum by enzyme-linked immunosorbent assay from D0 (within 24 hr of injury, prior to erythropoietin/vehicle administration) to D5. Biomarker concentrations were compared between injury severities, diffuse versus focal traumatic brain injury and erythropoietin or placebo treatment groups. Ubiquitin carboxy-terminal hydrolase L1 peaked at 146.0 ng/mL on D0, significantly decreased to 84.30 ng/mL on D1, and declined thereafter. Phosphorylated neurofilament heavy-chain levels were lowest at D0 and peaked on D5 at 157.9 ng/mL. D0 ubiquitin carboxy-terminal hydrolase L1 concentrations were higher in diffuse traumatic brain injury. Peak phosphorylated neurofilament heavy-chain levels on D3 and D4 correlated with Glasgow Outcome Score-Extended, predicting poor outcome. Erythropoietin did not reduce concentrations of ubiquitin carboxy-terminal hydrolase L1 or phosphorylated neurofilament heavy-chain.

CONCLUSIONS

Serum ubiquitin carboxy-terminal hydrolase L1 and phosphorylated neurofilament heavy-chain increase after traumatic brain injury reflecting early neuronal and progressive axonal injury. Consistent with lack of improved outcome in traumatic brain injury patients treated with erythropoietin, biomarker concentrations and profiles were not affected by erythropoietin. Pharmacokinetics of erythropoietin suggest that the dose given was possibly too low to exert neuroprotection.

Immune-Based Therapies for Traumatic Brain Injury: Insights from Pre-Clinical Studies

Traumatic Brain Injury (TBI) is a major public health problem. It is the leading cause of death and disability, especially among children and young adults. The neurobiology basis underlying TBI pathophysiology remains to be fully revealed. Over the past years, emerging evidence has supported the hypothesis that TBI is an inflammatory based condition, paving the way for the development of potential therapeutic targets. There is no treatment capable to prevent or minimize TBIassociated outcomes. Therefore, the search for effective therapies is a priority goal. In this context, animal models have become valuable tools to study molecular and cellular mechanisms involved in TBI pathogenesis as well as novel treatments. Herein, we discuss therapeutic strategies to treat TBI focused on immunomodulatory and/or anti-inflammatory approaches in the pre-clinical setting.

A Systematic Review of Closed Head Injury Models of Mild Traumatic Brain Injury in Mice and Rats

Mild TBI (mTBI) is a significant health concern. Animal models of mTBI are essential for understanding mechanisms, and pathological outcomes, as well as to test therapeutic interventions. A variety of closed head models of mTBI that incorporate different aspects (i.e., biomechanics) of the mTBI have been reported. The aim of the current review was to compile a comprehensive list of the closed head mTBI rodent models, along with the common data elements, and outcomes, with the goal to summarize the current state of the field. Publications were identified from a search of PubMed and Web of Science and screened for eligibility following PRISMA guidelines. Articles were included that were closed head injuries in which the authors classified the injury as mild in rats or mice. Injury model and animal-specific common data elements, as well as behavioral and histological outcomes, were collected and compiled from a total of 402 articles. Our results outline the wide variety of methods used to model mTBI. We also discovered that female rodents and both young and aged animals are under-represented in experimental mTBI studies. Our findings will aid in providing context comparing the injury models and provide a starting point for the selection of the most appropriate model of mTBI to address a specific hypothesis. We believe this review will be a useful starting place for determining what has been done and what knowledge is missing in the field to reduce the burden of mTBI.

Erythropoietin Treatment in Traumatic Brain Injury: Operation Brain Trauma Therapy

Experimental studies targeting traumatic brain injury (TBI) have reported that erythropoietin (EPO) is an endogenous neuroprotectant in multiple models. In addition to its neuroprotective effects, it has also been shown to enhance reparative processes including angiogenesis and neurogenesis. Based on compelling pre-clinical data, EPO was tested by the Operation Brain Trauma Therapy (OBTT) consortium to evaluate therapeutic potential in multiple TBI models along with biomarker assessments. Based on the pre-clinical TBI literature, two doses of EPO (5000 and 10,000 IU/kg) were tested given at 15 min after moderate fluid percussion brain injury (FPI), controlled cortical impact (CCI), or penetrating ballistic-like brain injury (PBBI) with subsequent behavioral, histopathological, and biomarker outcome assessments. There was a significant benefit on beam walk with the 5000 IU dose in CCI, but no benefit on any other motor task across models in OBTT. Also, no benefit of EPO treatment across the three TBI models was noted using the Morris water maze to assess cognitive deficits. Lesion volume analysis showed no treatment effects after either FPI or CCI; however, with the 5000 IU/kg dose of EPO, a paradoxical increase in lesion volume and percent hemispheric tissue loss was seen after PBBI. Biomarker assessments included measurements of glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase-L1 (UCH-L1) in blood at 4 or 24 h after injury. No treatment effects were seen on biomarker levels after FPI, whereas treatment at either dose exacerbated the increase in GFAP at 24 h in PBBI but attenuated 24-4 h delta UCH-L1 levels at high dose in CCI. Our data indicate a surprising lack of efficacy of EPO across three established TBI models in terms of behavioral, histopathological, and biomarker assessments. Although we cannot rule out the possibility that other doses or more prolonged treatment could show different effects, the lack of efficacy of EPO reduced enthusiasm for its further investigation in OBTT.

Creatine in the central nervous system: From magnetic resonance spectroscopy to creatine deficiencies

Creatine (Cr) is an important organic compound acting as intracellular high-energy phosphate shuttle and in energy storage. While located in most cells where it plays its main roles in energy metabolism and cytoprotection, Cr is highly concentrated in muscle and brain tissues, in which Cr also appears to act in osmoregulation and neurotransmission. This review discusses the basis of Cr metabolism, synthesis and transport within brain cells. The importance of Cr in brain function and the consequences of its impaired metabolism in primary and secondary Cr deficiencies are also discussed. Cr and phosphocreatine (PCr) in living systems can be well characterized using in vivo magnetic resonance spectroscopy (MRS). This review describes how ¹H MRS allows the measurement of Cr and PCr, and how ³¹P MRS makes it possible to estimate the creatine kinase (CK) rate constant and so detect dynamic changes in the Cr/PCr/CK system. Absolute quantification by MRS using creatine as internal reference is also debated. The use of in vivo MRS to study brain Cr in a non-invasive way is presented, as well as its use in clinical and preclinical studies, including diagnosis and treatment follow-up in patients.

Anti-edema effects of rhEpo in experimental traumatic brain injury

PURPOSE

Traumatic brain injury (TBI) is one of the leading causes of disability and death which begins with the formation of edema as the persistent primary causative factor in TBI. Although medical management of cerebral edema by hypothermia, ventriculostomy, mannitol or hypertonic saline have been effective in treating edema, many of these therapies end up with some neurologic deficits, necessitating novel treatment options for treating post-TBI edema. This study investigated edema reducing effects of recombinant human Erythropoietin (rhEPO) in reducing acute brain edema in the CCI mouse model of TBI.

METHODS

Anti-edema effects of rhEpo in reducing acute brain edema after injury in the CCI mouse model of TBI were assessed by T2 weighted magnetic resonance imaging (T2wMRI) as the accurate detector of brain edema in correlation with Western blot analysis of cerebral aquaporin 4 (AQP4) index as the critical marker of edema.

RESULTS

Results show that rhEpo treatment significantly reduced brain edema with concomitant reduction in AQP4 immunoexpression in the CCI mouse model of TBI.

CONCLUSION

Current results emphasize clinical utility of rhEpo in treating post-TBI edema.

Erythropoietin and Its Derivates Modulate Mitochondrial Dysfunction after Diffuse Traumatic Brain Injury

Inhibiting the opening of mitochondrial permeability transition pore (mPTP), thereby maintaining the mitochondrial membrane potential and calcium homeostasis, could reduce the induction of cell death. Although recombinant human erythropoietin (rhEpo) and carbamylated erythropoietin (Cepo) were shown to prevent apoptosis after traumatic brain injury (TBI), their impact on mPTP is yet unknown. Thirty minutes after diffuse TBI (impact-acceleration model), rats were intravenously administered a saline solution (TBI-saline), 5000 UI/kg rhEpo (TBI-rhEpo) or 50 μg/kg Cepo (TBI-Cepo). A fourth group received no TBI insult (sham-operated) (n = 11 rats per group). Post-traumatic brain edema was measured using magnetic resonance imaging. A first series of experiments was conducted 2 h after TBI (or equivalent) to investigate the mitochondrial function with the determination of thresholds for mPTP opening and ultrastructural mitochondrial changes. In addition, the intramitochondrial calcium content [Caim] was measured. In a second series of experiments, brain cell apoptosis was assessed at 24 h post-injury. TBI-rhEpo and TBI-Cepo groups had a reduced brain edema compared with TBI-saline. They had higher threshold for mPTP opening with succinate as substrate: 120 (120-150) (median, interquartiles) and 100 (100-120) versus 80 (60-90) nmol calcium/mg protein in TBI-saline, respectively (p < 0.05). Similar findings were shown with glutamate-malate as substrate. TBI-rhEpo and Cepo groups had less morphological mitochondrial disruption in astrocytes. The elevation in [Caim] after TBI was not changed by rhEpo and Cepo treatment. Finally, rhEpo and Cepo reduced caspase-3 expression at 24 h post-injury. These results indicate that rhEpo and Cepo could modulate mitochondrial dysfunction after TBI. The mechanisms involved are discussed.

Therapies negating neuroinflammation after brain trauma

Traumatic brain injury (TBI) elicits a complex secondary injury response, with neuroinflammation as a crucial central component. Long thought to be solely a deleterious factor, the neuroinflammatory response has recently been shown to be far more intricate, with both beneficial and detrimental consequences depending on the timing, magnitude and specific immune composition of the response post-injury. Despite extensive preclinical and clinical research into mechanisms of secondary injury after TBI, no effective neuroprotective therapy has been identified, with potential candidates repeatedly proving disappointing in the clinic. The neuroinflammatory response offers a promising avenue for therapeutic targeting, aiming to quell the deleterious consequences without influencing its function in providing a neurotrophic environment supportive of repair. The present review firstly describes the findings of recent clinical trials that aimed to modulate inflammation as a means of neuroprotection. Secondly, we discuss promising multifunctional and single-target anti-inflammatory candidates either currently in trial, or with ample experimental evidence supporting clinical application. This article is part of a Special Issue entitled SI:Brain injury and recovery.

Characterization of protein alterations in damaged axons in the brainstem following traumatic brain injury using fourier transform infrared microspectroscopy: a preliminary study

Axonal injury contributes greatly to neurological dysfunction following traumatic brain injury (TBI), but current histological diagnostic methods are limited in identifying the pathological profiles of injured axons and unable to provide an objective and accurate quantification. Fourier transform infrared microspectroscopy (FTIRM) has the ability to offer macromolecular bioinformatics of the tissues including biochemical composition and structure by calculating band absorption intensity. In this study, axonal injury in the brainstem of rats with traumatic brain injury at 72 h post-trauma, which was confirmed with beta-amyloid precursor protein (β-APP) immunostaining, was detected with FTIRM technique. The lower intensity of infrared absorbance under the amide I band corresponds strongly to the area of axonal injury, and further analysis of amide I band shows significant differences in protein conformation between injured and normal axons. The findings indicate that using FTIRM technique, the amide I band has potentials to be a infrared spectral marker of axonal injury.

Factors affecting cerebral oxygenation in hemodialysis patients: cerebral oxygenation associates with pH, hemodialysis duration, serum albumin concentration, and diabetes mellitus

Background

Patients undergoing hemodialysis (HD) often develop cerebral disease complications. Furthermore, cerebral regional saturation of oxygen (rSO₂) was previously reported to be significantly lower in HD patients than in healthy subjects. We aimed to identify the factors affecting the cerebral rSO₂ in HD patients.

Methods

Fifty-four HD patients (38 men and 16 women; mean age, 67.7 ± 1.2 years, HD duration, 6.5 ± 1.9 years) were recruited. Cerebral rSO₂ was monitored at the forehead before HD using an INVOS 5100C (Covidien Japan, Tokyo, Japan).

Results

The rSO₂ levels were significantly lower in HD patients compared with healthy controls (49.5 ± 1.7% vs. 68.9 ± 1.6%, p <0.001). Multiple regression analysis showed that cerebral rSO₂ independently associated with pH (standardized coefficient: -0.35), HD duration (standardized coefficient: -0.33), and serum albumin concentration (standardized coefficient: 0.28). Furthermore, the rSO₂ was significantly lower in HD patients with diabetes mellitus (DM), compared with patients without DM (46.8 ± 1.7% vs. 52.1 ± 1.8%, p <0.05).

Conclusions

In HD patients, cerebral rSO₂ was affected by multiple factors, including pH, HD duration, and serum albumin concentration. Furthermore, this is the first report describing significantly lower levels of rSO₂ in HD patients with DM than in those without DM.

Erythropoietin improves synaptic plasticity and memory deficits by decrease of the neurotransmitter release probability in the rat model of Alzheimer's disease

INTRODUCTION

Several studies indicate erythropoietin (Epo) to have remarkable neuroprotection in various central nervous system disorders, including Alzheimer's disease (AD). Amyloid beta (Aβ) is believed to be responsible for the synaptic dysfunction that occurs in AD. Therefore, the present study is aimed to investigate the effects of Epo on the Aβ-induced impairments in learning-memory and hippocampal synaptic plasticity.

MATERIALS AND METHODS

Male Sprague-Dawley rats (200-250 g) were used in this study. After the injection of Aβ, they were injected intra-peritoneal with Epo in the Aβ+Epo group or its vehicle in the Aβ+V group every other day for 12 days. A shuttle box apparatus was used for the passive avoidance learning and memory study. Moreover, paired-pulse ratio (PPR) was monitored before and after tetanic stimulation.

RESULTS

Bilateral injection of Aβ decreased step-through latency (STL), whereas the 12 day administration of Epo significantly improved memory performance in Aβ+Epo group. The field potential recording demonstrated that the in vivo administration of Aβ25-35 led to extreme inhibition in long-term potentiation, this inhibition was accompanied by a significant increase of the normalized PPR (PPR after HFS/PPR before HFS) as an index for release probability. However, administration of Epo recovers the magnitude of the LTP and the extent of normalized PPR.

CONCLUSION

The results of this study demonstrated that the injection of Aβ25-35 resulted in impaired LTP and the memory process, which is likely mediated through increasing the release probability of neurotransmitter vesicles. In addition, treatment with Epo improved the Aβ-induced deficits in memory and LTP induction, probably via recovering the release probability.

Mechanical tissue resuscitation at the site of traumatic brain injuries reduces the volume of injury and hemorrhage in a swine model

BACKGROUND

Traumatic brain injuries (TBIs) continue to be a devastating problem with limited treatment options. Previous research applying controlled vacuum to TBI in a rat model resulted in smaller injuries and more rapid recovery.

OBJECTIVE

To examine the effects of the application of a controlled vacuum (mechanical tissue resuscitation) to TBI in a large-animal model. The magnitude of vacuum, length of application, and length of delay between injury and the application of mechanical tissue resuscitation were investigated.

METHODS

Localized, controlled cortical injuries were created in swine. Vacuums of -50 and -100 mm Hg were compared. Mechanical tissue resuscitation for 3 or 5 days was compared. Delays of 0, 3, or 6 hours between the creation of the TBI and the initiation of mechanical tissue resuscitation were examined. Analysis included histological assessments, computed tomographic perfusion, and magnetic resonance imaging (T2, proton magnetic spectra).

RESULTS

A -100 mm Hg vacuum resulted in significantly smaller mean contused brain and hemorrhage volumes compared with -50 mm Hg and controls. Magnetic resonance spectra of treated animals returned to near baseline values. All 10 animals with 5-day mechanical tissue resuscitation treatment survived. Three of 6 animals treated for 3 days died after the discontinuation of treatment. A 3-hour delay resulted in similar results as immediate treatment. A 6-hour delay produced significant, but lesser responses.

CONCLUSION

Application of mechanical tissue resuscitation to TBI was efficacious in the large-animal model. Application of -100 mm Hg for 5 days resulted in significantly improved outcomes. Delays of up to 3 hours between injury and the initiation of treatment did not diminish the efficacy of the mechanical tissue resuscitation treatment.

Pharmacotherapy of traumatic brain injury: state of the science and the road forward: report of the Department of Defense Neurotrauma Pharmacology Workgroup

Despite substantial investments by government, philanthropic, and commercial sources over the past several decades, traumatic brain injury (TBI) remains an unmet medical need and a major source of disability and mortality in both developed and developing societies. The U.S. Department of Defense neurotrauma research portfolio contains more than 500 research projects funded at more than $700 million and is aimed at developing interventions that mitigate the effects of trauma to the nervous system and lead to improved quality of life outcomes. A key area of this portfolio focuses on the need for effective pharmacological approaches for treating patients with TBI and its associated symptoms. The Neurotrauma Pharmacology Workgroup was established by the U.S. Army Medical Research and Materiel Command (USAMRMC) with the overarching goal of providing a strategic research plan for developing pharmacological treatments that improve clinical outcomes after TBI. To inform this plan, the Workgroup (a) assessed the current state of the science and ongoing research and (b) identified research gaps to inform future development of research priorities for the neurotrauma research portfolio. The Workgroup identified the six most critical research priority areas in the field of pharmacological treatment for persons with TBI. The priority areas represent parallel efforts needed to advance clinical care; each requires independent effort and sufficient investment. These priority areas will help the USAMRMC and other funding agencies strategically guide their research portfolios to ensure the development of effective pharmacological approaches for treating patients with TBI.

Erythropoietin improved cognitive function and decreased hippocampal caspase activity in rat pups after traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of acquired neurologic disability in children. Erythropoietin (EPO), an anti-apoptotic cytokine, improved cognitive outcome in adult rats after TBI. To our knowledge, EPO has not been studied in a developmental TBI model.

HYPOTHESIS

We hypothesized that EPO would improve cognitive outcome and increase neuron fraction in the hippocampus in 17-day-old (P17) rat pups after controlled cortical impact (CCI).

METHODS

EPO or vehicle was given at 1, 24, and 48 h after CCI and at post injury day (PID) 7. Cognitive outcome at PID14 was assessed using Novel Object Recognition (NOR). Hippocampal EPO levels, caspase activity, and mRNA levels of the apoptosis factors Bcl2, Bax, Bcl-xL, and Bad were measured during the first 14 days after injury. Neuron fraction and caspase activation in CA1, CA3, and DG were studied at PID2.

RESULTS

EPO normalized recognition memory after CCI. EPO blunted the increased hippocampal caspase activity induced by CCI at PID1, but not at PID2. EPO increased neuron fraction in CA3 at PID2. Brain levels of exogenous EPO appeared low relative to endogenous. Timing of EPO administration was associated with temporal changes in hippocampal mRNA levels of EPO and pro-apoptotic factors. Conclusion/Speculation: EPO improved recognition memory, increased regional hippocampal neuron fraction, and decreased caspase activity in P17 rats after CCI. We speculate that EPO improved cognitive outcome in rat pups after CCI as a result of improved neuronal survival via inhibition of caspase-dependent apoptosis early after injury.

Recombinant human erythropoietin improves the neurofunctional recovery of rats following traumatic brain injury via an increase in circulating endothelial progenitor cells

Previous studies show that circulating endothelial progenitor cells (EPCs) promote angiogenesis, which is a process associated with improved recovery in animal models of traumatic brain injury (TBI), and that recombinant human erythropoietin (rhEPO) plays a protective role following stroke. Thus, it was hypothesized that rhEPO would enhance recovery following brain injury in a rat model of TBI via an increase in the mobilization of EPCs and, subsequently, in angiogenesis. Flow cytometry assays using CD34- and CD133-specific antibodies were utilized to identify alterations in EPC levels, CD31 and CD34 antibody-stained brain tissue sections were used to quantify angiogenesis, and the Morris water maze (MWM) test and the modified Neurological Severity Score (mNSS) test were used to evaluate behavioral recovery. Compared with saline treatment, treatment with rhEPO significantly increased the number of circulating EPCs on days 1, 4, 7, and 14 (P < 0.05), improved spatial learning ability on days 24 and 25 (P < 0.05), and enhanced memory recovery on day 26 (P < 0.05). Moreover, rhEPO treatment decreased mNSS assessment scores on days 14, 21, and 25 (P < 0.05). There was a strong correlation between levels of circulating EPCs and CD34- and CD31-positive cells within the injured boundary zone (CD34(+) r = 0.910, P < 0.01; CD31(+) r = 0.894, P < 0.01) and the ipsilateral hippocampus (CD34(+) r = 0.841, P < 0.01; CD31(+) r = 0.835, P < 0.01). The present data demonstrate that rhEPO treatment improved functional outcomes in rats following TBI via an increase in the mobilization of EPCs and in subsequent angiogenesis.

Erythropoietin improves motor and cognitive deficit, axonal pathology, and neuroinflammation in a combined model of diffuse traumatic brain injury and hypoxia, in association with upregulation of the erythropoietin receptor

Background

Diffuse axonal injury is a common consequence of traumatic brain injury (TBI) and often co-occurs with hypoxia, resulting in poor neurological outcome for which there is no current therapy. Here, we investigate the ability of the multifunctional compound erythropoietin (EPO) to provide neuroprotection when administered to rats after diffuse TBI alone or with post-traumatic hypoxia.

Methods

Sprague–Dawley rats were subjected to diffuse traumatic axonal injury (TAI) followed by 30 minutes of hypoxic (Hx, 12% O₂) or normoxic ventilation, and were administered recombinant human EPO-α (5000 IU/kg) or saline at 1 and 24 hours post-injury. The parameters examined included: 1) behavioural and cognitive deficit using the Rotarod, open field and novel object recognition tests; 2) axonal pathology (NF-200); 3) callosal degradation (hematoxylin and eosin stain); 3) dendritic loss (MAP2); 4) expression and localisation of the EPO receptor (EpoR); 5) activation/infiltration of microglia/macrophages (CD68) and production of IL-1β.

Results

EPO significantly improved sensorimotor and cognitive recovery when administered to TAI rats with hypoxia (TAI + Hx). A single dose of EPO at 1 hour reduced axonal damage in the white matter of TAI + Hx rats at 1 day by 60% compared to vehicle. MAP2 was decreased in the lateral septal nucleus of TAI + Hx rats; however, EPO prevented this loss, and maintained MAP2 density over time. EPO administration elicited an early enhanced expression of EpoR 1 day after TAI + Hx compared with a 7-day peak in vehicle controls. Furthermore, EPO reduced IL-1β to sham levels 2 hours after TAI + Hx, concomitant to a decrease in CD68 positive cells at 7 and 14 days.

Conclusions

When administered EPO, TAI + Hx rats had improved behavioural and cognitive performance, attenuated white matter damage, resolution of neuronal damage spanning from the axon to the dendrite, and suppressed neuroinflammation, alongside enhanced expression of EpoR. These data provide compelling evidence of EPO’s neuroprotective capability. Few benefits were observed when EPO was administered to TAI rats without hypoxia, indicating that EPO’s neuroprotective capacity is bolstered under hypoxic conditions, which may be an important consideration when EPO is employed for neuroprotection in the clinic.

Changes in brain tissue oxygenation after treatment of diffuse traumatic brain injury by erythropoietin

OBJECTIVES

To investigate the effects of recombinant human erythropoietin on brain oxygenation in a model of diffuse traumatic brain injury.

DESIGN

Adult male Wistar rats.

SETTING

Neurosciences and physiology laboratories.

INTERVENTIONS

Thirty minutes after diffuse traumatic brain injury (impact-acceleration model), rats were intravenously administered with either a saline solution or a recombinant human erythropoietin (5000 IU/kg). A third group received no traumatic brain injury insult (sham-operated).

MEASUREMENTS AND MAIN RESULTS

Three series of experiments were conducted 2 hours after traumatic brain injury to investigate: 1) the effect of recombinant human erythropoietin on brain edema using diffusion-weighted magnetic resonance imaging and measurements of apparent diffusion coefficient (n = 11 rats per group); local brain oxygen saturation, mean transit time, and blood volume fraction were subsequently measured using a multiparametric magnetic resonance-based approach to estimate brain oxygenation and brain perfusion in the neocortex and caudoputamen; 2) the effect of recombinant human erythropoietin on brain tissue PO₂ in similar experiments (n = 5 rats per group); and 3) the cortical ultrastructural changes after treatment (n = 1 rat per group). Compared with the sham-operated group, traumatic brain injury saline rats showed a significant decrease in local brain oxygen saturation and in brain tissue PO₂ alongside brain edema formation and microvascular lumen collapse at H2. Treatment with recombinant human erythropoietin reversed all of these traumatic brain injury-induced changes. Brain perfusion (mean transit time and blood volume fraction) was comparable between the three groups of animals.

CONCLUSION

Our findings indicate that brain hypoxia can be related to microcirculatory derangements and cell edema without evidence of brain ischemia. These changes were reversed with post-traumatic administration of recombinant human erythropoietin, thus offering new perspectives in the use of this drug in brain injury.

The neuroprotective and neurorescue effects of carbamylated erythropoietin Fc fusion protein (CEPO-Fc) in a rat model of Parkinson's disease

Parkinson's disease is characterized by progressive degeneration of dopaminergic neurons. Thus the development of therapeutic neuroprotection and neurorescue strategies to mitigate disease progression is important. In this study we evaluated the neuroprotective/rescue effects of erythropoietin Fc fusion protein (EPO-Fc) and carbamylated erythropoietin Fc fusion protein (CEPO-Fc) in a rat model of Parkinson's disease. Adult female Sprague-Dawley rats received intraperitoneal injection of EPO-Fc, CEPO-Fc or PBS. Behavioral evaluations consisted of rota-rod, cylinder and amphetamine-induced rotation tests. In the neuroprotection experiment, the CEPO-Fc group demonstrated significant improvement compared with the EPO-Fc group on the amphetamine-induced rotation test throughout the four-week follow-up period. Histologically, significantly more tyrosine hydroxylase (TH)-positive neurons were recognized in the substantia nigra (SN) pars compacta in the CEPO-Fc group than in the PBS and EPO-Fc groups. In the neurorescue experiment, rats receiving CEPO-Fc showed significantly better behavioural scores than those receiving PBS. The histological data concerning striatum also showed that the CEPO-Fc group had significantly better preservation of TH-positive fibers compared to the PBS and EPO-Fc groups. Importantly, there were no increases in hematocrit or hemoglobin levels in the CEPO-Fc group in either the neuroprotection or the neurorescue experiments. In conclusion, the newly developed CEPO-Fc might confer neuroprotective and neurorescue benefits in a rat model of Parkinson's disease without the side effects associated with polycythemia. CEPO-Fc might be a therapeutic tool for patients with Parkinson's disease.

Extracellular matrix metalloproteinase inducer is associated with severity of brain oedema following experimental subarachnoid haemorrhage in rats

OBJECTIVE

Brain oedema is a major cause of clinical deterioration and death following brain trauma; cellular mechanisms involved in its development remain elusive. This study investigated the role of extracellular matrix metalloproteinase inducer (EMMPRIN) in brain oedema.

METHODS

The monofilament puncture model was used to induce subarachnoid haemorrhage. Adult male Sprague-Dawley rats were divided into five groups (n = 20 per group): sham-operated, sacrificed immediately after surgery (sham group); sacrificed 12, 24 or 72 h after subarachnoid haemorrhage induction (SAH-12, SAH-24 and SAH-72 groups, respectively); treated with EMMPRIN inhibitor immediately after subarachnoid haemorrhage, sacrificed at 24 h (SAH-inhibition group). Mean brain water content, and EMMPRIN mRNA and protein levels, were determined.

RESULTS

Compared with the sham group, mean brain water content, EMMPRIN mRNA and protein levels in the SAH-12, SAH-24 and SAH-72 groups increased rapidly and significantly (maximal at 24 h). EMMPRIN inhibition significantly reduced mean brain water content and EMMPRIN mRNA and protein levels in the SAH-inhibition group, compared with the SAH-24 group.

CONCLUSIONS

EMMPRIN upregulation may be important in the formation of brain oedema; inhibition of EMMPRIN activity may provide a potential approach to reduce oedema after subarachnoid haemorrhage.

Effect of different mild hypoxia manipulations on kainic acid-induced seizures in the hippocampus of rats

The protective effect of the mild hypoxia to the epilepsy has been widely tested. Although it is found that the hypoxia protects the brain by up-regulation of hypoxia-inducible factor-1α, few focused on systematic comparisons between different mild hypoxia manipulations and their effects. The male Sprague-Dawley rats were observed following exposure to hypoxia before and after epilepsy for 3 days with 90 min per day. The effects of different mild hypoxia manipulations on kainic acid-induced epilepsy were compared from the perspective of morphology, molecular biology and behavioral test. Results showed that different mild hypoxia manipulations could inhibit the cell apoptosis of kainic acid-induced rat hippocampus and improve their physiological functions. The effect of preconditioning group was better than that of postconditioning group and that of preconditioning and postconditioning with mild hypoxia group was the best among all the groups. The result showed that the preconditioning and postconditioning of mild hypoxia was recommended pre- and post-epilepsy and exposure to mild hypoxia should be prolonged. These findings might provide new ideas and methods for the clinical treatment of epilepsy.

A new method for modulating traumatic brain injury with mechanical tissue resuscitation

BACKGROUND

Traumatic brain injuries remain a treatment enigma with devastating late results. As terminally differentiated tissue, the brain retains little capacity to regenerate, making early attempts to preserve brain cells after brain injury essential.

OBJECTIVE

To resuscitate damaged tissue by modulating edema, soluble cytokines, and metabolic products in the "halo" of damaged tissue around the area of central injury that progressively becomes compromised. By re-equilibrating the zone of injury milieu, it is postulated neurons in this area will survive and function.

METHODS

Mechanical tissue resuscitation used localized, controlled, subatmospheric pressure directly to the area of controlled cortical impact injury and was compared with untreated injured controls and with sham surgery in a rat model. Functional outcome, T2 magnetic resonance imaging hyperintense volume, magnetic resonance imaging spectroscopy metabolite measurement, tissue water content, injury cavity area, and cortical volume were compared.

RESULTS

There were significant differences between mechanical tissue resuscitation treated and untreated groups in levels of myoinositol, N-acetylaspartate, and creatine. Treated animals had significantly less tissue swelling and density than the untreated animals. Nonviable brain tissue areas were smaller in treated animals than in untreated animals. Treated animals performed better than untreated animals in functional tests. Histological analysis showed the remaining viable ipsilateral cerebral area was 58% greater for treated animals than for untreated animals, and the cavity for treated animals was 95% smaller than for untreated animals 1 month after injury.

CONCLUSION

Mechanical tissue resuscitation with controlled subatmospheric pressure can significantly modulate levels of excitatory amino acids and lactate in traumatic brain injury, decrease the water content and volume of injured brain, improve neuronal survival, and speed functional recovery.

Guilty molecules, guilty minds? The conflicting roles of the innate immune response to traumatic brain injury

Traumatic brain injury (TBI) is a complex disease in the most complex organ of the body, whose victims endure lifelong debilitating physical, emotional, and psychosocial consequences. Despite advances in clinical care, there is no effective neuroprotective therapy for TBI, with almost every compound showing promise experimentally having disappointing results in the clinic. The complex and highly interrelated innate immune responses govern both the beneficial and deleterious molecular consequences of TBI and are present as an attractive therapeutic target. This paper discusses the positive, negative, and often conflicting roles of the innate immune response to TBI in both an experimental and clinical settings and highlights recent advances in the search for therapeutic candidates for the treatment of TBI.

Diffusion tensor imaging of diffuse axonal injury in a rat brain trauma model

Diffusion tensor imaging (DTI) was used to study traumatic brain injury. The impact-acceleration trauma model was used in rats. Here, in addition to diffusivities (mean, axial and radial), fractional anisotropy (FA) was used, in particular, as a parameter to characterize the cerebral tissue early after trauma. DTI was implemented at 7 T using fast spiral k-space sampling and the twice-refocused spin echo radiofrequency sequence for eddy current minimization. The method was carefully validated on different phantom measurements. DTI of a trauma group (n = 5), as well as a sham group (n = 5), was performed at different time points during 6 h following traumatic brain injury. Two cerebral regions, the cortex and corpus callosum, were analyzed carefully. A significant decrease in diffusivity in the trauma group versus the sham group was observed, suggesting the predominance of cellular edema in both cerebral regions. No significant FA change was detected in the cortex. In the corpus callosum of the trauma group, the FA indices were significantly lower. A net discontinuity in fiber reconstructions in the corpus callosum was observed by fiber tracking using DTI. Histological analysis using Hoechst, myelin basic protein and Bielschowsky staining showed fiber disorganization in the corpus callosum in the brains of the trauma group. On the basis of our histology results and the characteristics of the impact-acceleration model responsible for the presence of diffuse axonal injury, the detection of low FA caused by a drastic reduction in axial diffusivity and the presence of fiber disconnections of the DTI track in the corpus callosum were considered to be related to the presence of diffuse axonal injury.

Growth factors in ischemic stroke

Data from pre-clinical and clinical studies provide evidence that colony-stimulating factors (CSFs) and other growth factors (GFs) can improve stroke outcome by reducing stroke damage through their anti-apoptotic and anti-inflammatory effects, and by promoting angiogenesis and neurogenesis. This review provides a critical and up-to-date literature review on CSF use in stroke. We searched for experimental and clinical studies on haemopoietic GFs such as granulocyte CSF, erythropoietin, granulocyte-macrophage colony-stimulating factor, stem cell factor (SCF), vascular endothelial GF, stromal cell-derived factor-1α and SCF in ischemic stroke. We also considered studies on insulin-like growth factor-1 and neurotrophins. Despite promising results from animal models, the lack of data in human beings hampers efficacy assessments of GFs on stroke outcome. We provide a comprehensive and critical view of the present knowledge about GFs and stroke, and an overview of ongoing and future prospects.

Effects of erythropoietin on intracellular calcium concentration of rat primary cortical neurons

Erythropoietin (Epo) has been shown to afford neuroprotection in many experimental models. Although the cytosolic Ca(2+) concentration ([Ca(2+)](i)) is an important factor regulating cell survival, the effects of Epo on [Ca(2+)](i) in neurons are not fully elucidated. We studied the effects of human recombinant Epo on [Ca(2+)](i) of rat primary cortical neurons in normal and excitotoxic conditions. Changes in [Ca(2+)](i) were measured using fura-2 microfluorometry in rat primary cortical cultures. In the control condition with 2mM Mg(2+) in the bath solution, Epo at 4 u/ml significantly increased the fluorescence ratio, but the Epo-induced increase in the fluorescence ratio was abolished by omission of Ca(2+) from the bath solution and by the addition of cadmium. Omission of Mg(2+) and supplementation with glycine resulted in basal and periodic increases in the fluorescence ratio, due to sustained activation of N-methyl-d-asparate (NMDA) receptors. Epo at 0.4 and 4 u/ml significantly decreased the fluorescence ratio in this condition, and this effect was attenuated by the phosphoinositide 3-kinase (PI3K) inhibitors, LY 294002 and wortmannin, and the Ca-activated K channel blocker, iberiotoxin. In the presence of Mg(2+) and exogenous glutamate, 4 but not 0.4 u/ml Epo slightly but significantly reduced the [Ca(2+)](i) elevation. These results suggest that Epo increased [Ca(2+)](i) in cortical neurons by inducing Ca(2+) entry in the control condition but decreased [Ca(2+)](i) in the Mg(2+)-free excitotoxic condition, at least in part via PI3K-dependent activation of Ca-activated K channels. Reduction of [Ca(2+)](i) by Epo in the excitotoxic condition may contribute to neuroprotection.

Pharmacologic amelioration of severe hypoglycemia-induced neuronal damage

Hypoglycemia is a common complication for insulin treated people with diabetes. Severe hypoglycemia, which occurs in the setting of excess or ill-timed insulin administration, has been shown to cause brain damage. Previous pre-clinical studies have shown that memantine (an N-methyl-d-aspartate receptor antagonist) and erythropoietin can be neuroprotective in other models of brain injury. We hypothesized that these agents might also be neuroprotective in response to severe hypoglycemia-induced brain damage. To test this hypothesis, 9-week old, awake, male Sprague-Dawley rats underwent hyperinsulinemic (0.2 U kg(-1)min(-1)) hypoglycemic clamps to induce severe hypoglycemia (blood glucose 10-15 mg/dl for 90 min). Animals were randomized into control (vehicle) or pharmacological treatments (memantine or erythropoietin). One week after severe hypoglycemia, neuronal damage was assessed by Fluoro-Jade B and hematoxylin and eosin staining of brain sections. Treatment with both memantine and erythropoietin significantly decreased severe hypoglycemia-induced neuronal damage in the cortex by 35% and 39%, respectively (both p<0.05 vs. controls). These findings demonstrate that memantine and erythropoietin provide a protective effect against severe hypoglycemia-induced neuronal damage.

Vitreal levels of erythropoietin are increased in patients with retinal vein occlusion and correlate with vitreal VEGF and the extent of macular edema

PURPOSE

This study compares vitreal levels of erythropoietin (EPO) in patients with retinal vein occlusion (RVO) with control subjects. In addition, it investigates different RVO disease parameters (time of vein occlusion, patient age, vitreal vascular endothelial growth factor (VEGF) levels, and extent of central macular edema) for possible correlations with vitreal EPO levels.

METHODS

Serum and vitreal EPO were measured from 6 patients with branch retinal vein occlusion, 6 patients with central retinal vein occlusion, and 12 control subjects (10 macular puckers and 2 macular holes).

RESULTS

Serum EPO levels (9.8 ± 4.9 mU/mL) did not differ between the RVO and control groups and were significantly lower than vitreal EPO levels in all groups. Vitreal EPO was elevated both in branch RVO (91 ± 59 mU/mL) and central RVO (182 ± 70 mU/mL) compared with controls (35 ± 24 mU/mL). Increased vitreal EPO correlated with higher vitreal VEGF (r = 0.64, P = 0.0008) and more pronounced central macular edema (r = 0.66, P = 0.001).

CONCLUSION

The results from this study indicate that EPO is locally expressed in the retina and that it is upregulated together with VEGF in RVO eyes. Because of its role both in neuroprotection and angiogenesis, ocular EPO might represent an interesting target to investigate in patients with RVO, especially in light of the current anti-VEGF treatments.

Erythropoietin as neuroprotective and neuroregenerative treatment strategy: comprehensive overview of 12 years of preclinical and clinical research

Erythropoietin (EPO), originally discovered as hematopoietic growth factor, has direct effects on cells of the nervous system that make it a highly attractive candidate drug for neuroprotection/neuroregeneration. Hardly any other compound has led to so much preclinical work in the field of translational neuroscience than EPO. Almost all of the >180 preclinical studies performed by many independent research groups from all over the world in the last 12 years have yielded positive results on EPO as a neuroprotective drug. The fact that EPO was approved for the treatment of anemia >20 years ago and found to be well tolerated and safe, facilitated the first steps of translation from preclinical findings to the clinic. On the other hand, the same fact, naturally associated with loss of patent protection, hindered to develop EPO as a highly promising therapeutic strategy for application in human brain disease. Therefore, only few clinical neuroprotection studies have been concluded, all with essentially positive and stimulating results, but no further development towards the clinic has occurred thus far. This article reviews the preclinical and clinical work on EPO for the indications neuroprotection/neuroregeneration and cognition, and hopefully will stimulate new endeavours promoting development of EPO for the treatment of human brain diseases.

Synergistic benefits of erythropoietin and simvastatin after traumatic brain injury

Simvastatin and recombinant human erythropoietin (rhEpo) are implicated as potential therapeutic candidates for traumatic brain injury (TBI). Prominent effects of simvastatin include its anti-inflammatory, neurotrophic and neuroregenerative actions studied in various models of neuronal injury. On the other hand, rhEpo has been shown to promote cell survival mechanisms by producing anti-apoptotic and cell proliferative actions. Beneficial effects of rhEpo and statin monotherapies have been well studied. However, there are no reports showing combined use of rhEpo and statins after TBI. This investigation examined if combined efficacy of cell proliferative ability of rhEpo along with the neuroregenerative ability of simvastatin will render maximum recovery in a controlled cortical impact (CCI) mouse model of TBI. Results showed that compared to baseline TBI, rhEpo was more effective than simvastatin in promoting cell proliferation while simvastatin was more effective than rhEpo in restoring axonal damage following TBI. Combined treatment with simvastatin and rhEpo maximally restored axonal integrity while simultaneously inducing greater proliferation of newly formed cells resulting in better functional recovery after TBI than either alone. This is the first study showing the efficacy of erythropoietin-simvastatin combinational therapeutic approach in achieving greater structural and cognitive recovery after TBI.

Effect of recombinant human erythropoietin on serum S100B protein and interleukin-6 levels after traumatic brain injury in the rat

Erythropoietin (EPO) has a neuroprotective effect in the animal model of ischemia/hypoxia, but the mechanisms underlying the EPO effect in traumatic brain injury (TBI) are not well understood. This study examined the potential neuroprotective mechanisms of recombinant human EPO (rhEPO) in rats after TBI. Sixty healthy adult male Sprague-Dawley rats were randomly divided into 5 groups: 1000 U/kg rhEPO-treated, 3000 U/kg rhEPO-treated, 5000 U/kg rhEPO-treated, citicoline, and normal saline (control) groups. The TBI model was based on the modified Feeney's free falling model. Serum samples were collected at 6 hours, 24 hours, 3 days, 5 days, and 7 days after trauma. The serum S100B protein and interleukin-6 (IL-6) levels were measured after treatment in each group with double antibody sandwich enzyme-linked immunosorbent assay. Both serum S100B protein and IL-6 levels were significantly lower in 3000 U/kg rhEPO-treated and 5000 U/kg rhEPO-treated groups (p < 0.001). The decrease in serum S100B protein level was correlated with the dosage of rhEPO. Medium doses of rhEPO achieved the optimum decreases in the serum IL-6 level. Therefore, inhibition of the composition and secretion of S100B protein and IL-6 levels by EPO might be one of the mechanisms involved in decreasing inflammatory reaction in the brain, and may be responsible for the neuroprotective effect after TBI.

Erythropoietin 2nd cerebral protection after acute injuries: a double-edged sword?

Over the past 15 years, a large body of evidence has revealed that the cytokine erythropoietin exhibits non-erythropoietic functions, especially tissue-protective effects. The discovery of EPO and its receptors in the central nervous system and the evidence that EPO is made locally in response to injury as a protective factor in the brain have raised the possibility that recombinant human EPO (rhEPO) could be administered as a cytoprotective agent after acute brain injuries. This review highlights the potential applications of rhEPO as a neuroprotectant in experimental and clinical settings such as ischemia, traumatic brain injury, and subarachnoid and intracerebral hemorrhage. In preclinical studies, EPO prevented apoptosis, inflammation, and oxidative stress induced by injury and exhibited strong neuroprotective and neurorestorative properties. EPO stimulates vascular repair by facilitating endothelial progenitor cell migration into the brain and neovascularisation, and it promotes neurogenesis. In humans, small clinical trials have shown promising results but large prospective randomized studies failed to demonstrate a benefit of EPO for brain protection and showed unwanted side effects, especially thrombotic complications. Recently, regions have been identified within the EPO molecule that mediate tissue protection, allowing the development of non-erythropoietic EPO variants for neuroprotection conceptually devoid of side effects. The efficacy and the safety profile of these new compounds are still to be demonstrated to obtain, in patients, the benefits observed in experimental studies.

Short-term effect of erythropoietin on brain lesions and aquaporin-4 expression in a hypoxic-ischemic neonatal rat model assessed by magnetic resonance diffusion weighted imaging and immunohistochemistry

Erythropoietin (Epo) is an endogenous cytokine that regulates hematopoiesis and is widely used to treat anemia. In addition, it has recently increased interest in the neurosciences since the new concept of Epo as a neuroprotective agent has emerged. The potential protective effect of human recombinant Epo (r-hu-Epo) on a hypoxic-ischemic (HI) pup rat model was studied. Cerebral HI was obtained by permanent left carotid artery ligature of pups followed by a 2-h hypoxia. Three hours after carotid occlusion, brain lesions were assessed by magnetic resonance diffusion weighted imaging. Intraperitoneal administration of r-hu-Epo (30,000 U/kg dose) limited both the HI-induced brain lesion area and the decrease in apparent diffusion coefficient (ADC) in the lesion. To identify potential mechanisms underlying the effects of Epo, immunohistochemical detection of caspase-3 and water channel protein aquaporin-4 (AQP4) were performed. No early apoptosis was detected, but up-regulation of AQP4 expression was observed in HI pups that received r-hu-Epo compared with HI animals without treatment. This study demonstrates an early neuroprotective effect of Epo with regard to brain lesion area and ADC values. One possible mechanism of Epo for decreasing brain edema and cellular swelling could be a better clearance of water excess in brain tissue, a process possibly mediated by AQP4.

Erythropoietin improves histological and functional outcomes after traumatic brain injury in mice in the absence of the neural erythropoietin receptor

Erythropoietin (EPO), essential for erythropoiesis, provides neuroprotection. The EPO receptor (EPOR) is expressed in both neural and non-neural cells in the brain. This study was designed to test the hypothesis that EPO provides beneficial therapeutic effects, even in the absence of the neural EPOR. In this study, EPOR-null mice were rescued with selective EpoR expression driven by the endogenous EpoR promoter in hematopoietic tissue, but not in the neural cells. Anesthetized young adult female EPOR-null and wild-type mice were subjected to traumatic brain injury (TBI) induced by controlled cortical impact. EPO (5000 U/kg) or saline was intraperitoneally administered at 6 h and 3 and 7 days post-injury. Sensorimotor and spatial learning functions were assessed. Expression of EPOR and its downstream signal proteins were evaluated by Western blot analysis. Our data demonstrated that EPO treatment significantly reduced cortical tissue damage and hippocampal cell loss, and improved spatial learning following TBI in both the wild-type and EPOR-null mice. EPO treatment significantly improved sensorimotor functional recovery, with better outcomes in the wild-type mice. EPO treatment upregulated anti-apoptotic proteins (p-Akt and Bcl-XL) in the ipsilateral hippocampus and cortex of the injured wild-type and EPOR-null mice. These data demonstrate that EPO significantly provides neuroprotection following TBI, even in the absence of EPOR in the neural cells, suggesting that its therapeutic benefits may be mediated through vascular protection.

Recent advances in pharmacologic neuroprotection

Although there is a continual improvement in the understanding of the pathophysiology of brain ischaemia and reperfusion, the pharmacological approach of treating or preventing brain ischaemic injury has had limited clinical impact so far. The great majority of clinical trials testing neuroprotectants for the treatment of acute ischaemic stroke have failed to demonstrate any benefit on any major outcome endpoint. Several strategies combining physiologic (oxygen, hypothermia), pharmacologic (erythopoietin derivatives) and thrombolytic therapies may, however, be promising in future, provided a more rigorous design of the clinical trials is achieved. The place of anaesthetics as clinical effective neuroprotectants in the perioperative period remains to be established.

The impact of erythropoietin on short-term changes in phosphorylation of brain protein kinases in a rat model of traumatic brain injury

We found that recombinant human erythropoietin (rhEPO) reduced significantly the development of brain edema in a rat model of diffuse traumatic brain injury (TBI) (impact-acceleration model). In this study, we investigated the molecular and intracellular changes potentially involved in these immediate effects. Brain tissue nitric oxide (NO) synthesis, phosphorylation level of two protein kinases (extracellular-regulated kinase (ERK)-1/-2 and Akt), and brain water content were measured 1 (H1) and 2 h (H2) after insult. Posttraumatic administration of rhEPO (5,000 IU/kg body weight, intravenously, 30 mins after injury) reduced TBI-induced upregulation of ERK phosphorylation, although it increased Akt phosphorylation at H1. These early molecular changes were associated with a reduction in brain NO synthesis at H1 and with an attenuation of brain edema at H2. Intraventricular administration of the ERK-1/-2 inhibitor, U0126, or the Akt inhibitor, LY294002, before injury showed that ERK was required for brain edema formation, and that rhEPO-induced reduction of edema could involve the ERK pathway. These results were obtained in the absence of any evidence of blood-brain barrier damage on contrast-enhanced magnetic resonance images. The findings of our study indicate that the anti edematous effect of rhEPO could be mediated through an early inhibition of ERK phosphorylation after diffuse TBI.

Erythropoiesis stimulating agent administration improves survival after severe traumatic brain injury: a matched case control study

OBJECTIVE

Erythropoiesis stimulating agent (ESA) administration may reduce mortality in severe traumatic brain injury (sTBI).

SUMMARY BACKGROUND DATA

It has been established that the administration of ESA in critically ill trauma victims has been associated with improved outcomes. Recent experimental and clinical data showed neuroprotective effects of ESA, however, the literature regarding impact on outcome in sTBI is lacking.

METHODS

: A retrospective matched case control study in patients with sTBI [head Abbreviated Injury Scale (AIS), >or=3] receiving ESA while in the surgical intensive care unit from January 1, 1996 to December 31, 2007 (n = 89), were matched 1 to 2 (n = 178) by age, gender, mechanism of injury, Glasgow Coma Scale, presence of hypotension on admission, Injury Severity Score, AIS for all body regions, and presence of anemia with patients who did not receive the agent. Each case's controls were chosen to have surgical intensive care unit length of stay more than or equal to the time from admission to first dose of ESA. The primary outcome measure in this study was mortality.

RESULTS

Cases and controls had similar age, gender, mechanisms of injury, incidence of hypotension, Glasgow Coma Scale on admission, Injury Severity Score, and AIS for all body regions. Although the ESA+ patients experienced protracted hospital length of stay and comparable surgical intensive care unit free days, they demonstrated a significantly lower in-hospital mortality in comparison to controls at 7.9% versus 24.2%, respectively (OR: 0.27; 95% CI = 0.12-0.62; P = 0.001).

CONCLUSIONS

Erythropoiesis stimulating agent administration in sTBI is associated with a significant in-hospital survival advantage without increase in morbidity. Prospective validation of our findings is warranted.

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.

Erythropoietin and its receptors in the brainstem of adults with fatal falciparum malaria

Background

Facilitation of endogenous neuroprotective pathways, such as the erythropoietin (Epo) pathway, has been proposed as adjuvant treatment strategies in cerebral malaria. Whether different endogenous protein expression levels of Epo or differences in the abundance of its receptor components could account for the extent of structural neuropathological changes or neurological complications in adults with severe malaria was investigated.

Methods

High sensitivity immunohistochemistry was used to assess the frequency, distribution and concordance of Epo and components of its homodimeric and heteromeric receptors, Epo receptor and CD131, within the brainstem of adults who died of severe malaria. The following relationships with Epo and its receptor components were also defined: (i) sequestration and indicators of hypoxia; (ii) vascular damage in the form of plasma protein leakage and haemorrhage; (iii) clinical complications and neuropathological features of severe malaria disease. Brainstems of patients dying in the UK from unrelated non-infectious causes were examined for comparison.

Results

The incidence of endogenous Epo in parenchymal brain cells did not greatly differ between severe malaria and non-neurological UK controls at the time of death. However, EpoR and CD131 labelling of neurons was greater in severe malaria compared with non-neurological controls (P = .009). EpoR labelling of vessels was positively correlated with admission peripheral parasite count (P = .01) and cerebral sequestration (P < .0001). There was a strong negative correlation between arterial oxygen saturation and EpoR labelling of glia (P = .001). There were no significant correlations with indicators of vascular damage, neuronal chromatolysis, axonal swelling or vital organ failure.

Conclusion

Cells within the brainstem of severe malaria patients showed protein expression of Epo and its receptor components. However, the incidence of endogeneous expression did not reflect protection from vascular or neuronal injury, and/or clinical manifestations, such as coma. These findings do not provide support for Epo as an adjuvant neuroprotective agent in adults with severe malaria.

New strategies for Alzheimer's disease and cognitive impairment

Approximately five million people suffer with Alzheimer's disease (AD) and more than twenty-four million people are diagnosed with AD, pre-senile dementia, and other disorders of cognitive loss worldwide. Furthermore, the annual cost per patient with AD can approach $200,000 with an annual population aggregate cost of $100 billion. Yet, complete therapeutic prevention or reversal of neurovascular injury during AD and cognitive loss is not achievable despite the current understanding of the cellular pathways that modulate nervous system injury during these disorders. As a result, identification of novel therapeutic targets for the treatment of neurovascular injury would be extremely beneficial to reduce or eliminate disability from diseases that lead to cognitive loss or impairment. Here we describe the capacity of intrinsic cellular mechanisms for the novel pathways of erythropoietin and forkhead transcription factors that may offer not only new strategies for disorders such as AD and cognitive loss, but also function as biomarkers for disease onset and progression.

Erythropoietin: a multimodal neuroprotective agent

The tissue protective functions of the hematopoietic growth factor erythropoietin (EPO) are independent of its action on erythropoiesis. EPO and its receptors (EPOR) are expressed in multiple brain cells during brain development and upregulated in the adult brain after injury. Peripherally administered EPO crosses the blood-brain barrier and activates in the brain anti-apoptotic, anti-oxidant and anti-inflammatory signaling in neurons, glial and cerebrovascular endothelial cells and stimulates angiogenesis and neurogenesis. These mechanisms underlie its potent tissue protective effects in experimental models of stroke, cerebral hemorrhage, traumatic brain injury, neuroinflammatory and neurodegenerative disease. The preclinical data in support of the use of EPO in brain disease have already been translated to first clinical pilot studies with encouraging results with the use of EPO as a neuroprotective agent.

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.