Therapeutic effects of erythropoietin on histological and functional outcomes following traumatic brain injury in rats are independent of hematocrit

A cannabidiol aminoquinone derivative activates the PP2A/B55α/HIF pathway and shows protective effects in a murine model of traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) is characterized by a primary mechanical injury and a secondary injury associated with neuroinflammation, blood-brain barrier (BBB) disruption and neurodegeneration. We have developed a novel cannabidiol aminoquinone derivative, VCE-004.8, which is a dual PPARγ/CB₂ agonist that also activates the hypoxia inducible factor (HIF) pathway. VCE-004.8 shows potent antifibrotic, anti-inflammatory and neuroprotective activities and it is now in Phase II clinical trials for systemic sclerosis and multiple sclerosis. Herein, we investigated the mechanism of action of VCE-004.8 in the HIF pathway and explored its efficacy in a preclinical model of TBI.

METHODS

Using a phosphoproteomic approach, we investigated the effects of VCE-004.8 on prolyl hydroxylase domain-containing protein 2 (PHD2) posttranslational modifications. The potential role of PP2A/B55α in HIF activation was analyzed using siRNA for B55α. To evaluate the angiogenic response to the treatment with VCE-004.8 we performed a Matrigel plug in vivo assay. Transendothelial electrical resistance (TEER) as well as vascular cell adhesion molecule 1 (VCAM), and zonula occludens 1 (ZO-1) tight junction protein expression were studied in brain microvascular endothelial cells. The efficacy of VCE-004.8 in vivo was evaluated in a controlled cortical impact (CCI) murine model of TBI.

RESULTS

Herein we provide evidence that VCE-004.8 inhibits PHD2 Ser125 phosphorylation and activates HIF through a PP2A/B55α pathway. VCE-004.8 induces angiogenesis in vivo increasing the formation of functional vessel (CD31/α-SMA) and prevents in vitro blood-brain barrier (BBB) disruption ameliorating the loss of ZO-1 expression under proinflammatory conditions. In CCI model VCE-004.8 treatment ameliorates early motor deficits after TBI and attenuates cerebral edema preserving BBB integrity. Histopathological analysis revealed that VCE-004.8 treatment induces neovascularization in pericontusional area and prevented immune cell infiltration to the brain parenchyma. In addition, VCE-004.8 attenuates neuroinflammation and reduces neuronal death and apoptosis in the damaged area.

CONCLUSIONS

This study provides new insight about the mechanism of action of VCE-004.8 regulating the PP2A/B55α/PHD2/HIF pathway. Furthermore, we show the potential efficacy for TBI treatment by preventing BBB disruption, enhancing angiogenesis, and ameliorating neuroinflammation and neurodegeneration after brain injury.

Potential Role of Adult Hippocampal Neurogenesis in Traumatic Brain Injury

Traumatic brain injury (TBI) is a serious cause of disability and death among young and adult individuals, displaying complex pathophysiology including cellular and molecular mechanisms that are not fully elucidated. Many experimental and clinical studies investigated the potential relationship between TBI and the process by which neurons are formed in the brain, known as neurogenesis. Currently, there are no available treatments for TBI's long-term consequences being the search for novel therapeutic targets, a goal of highest scientific and clinical priority. Some studies evaluated the benefits of treatments aimed at improving neurogenesis in TBI. In this scenario, herein, we reviewed current pre-clinical studies that evaluated different approaches to improving neurogenesis after TBI while achieving better cognitive outcomes, which may consist in interesting approaches for future treatments.

Growth Hormone Promotes Motor Function after Experimental Stroke and Enhances Recovery-Promoting Mechanisms within the Peri-Infarct Area

Motor impairment is the most common and widely recognised clinical outcome after stroke. Current clinical practice in stroke rehabilitation focuses mainly on physical therapy, with no pharmacological intervention approved to facilitate functional recovery. Several studies have documented positive effects of growth hormone (GH) on cognitive function after stroke, but surprisingly, the effects on motor function remain unclear. In this study, photothrombotic occlusion targeting the motor and sensory cortex was induced in adult male mice. Two days post-stroke, mice were administered with recombinant human GH or saline, continuing for 28 days, followed by evaluation of motor function. Three days after initiation of the treatment, bromodeoxyuridine was administered for subsequent assessment of cell proliferation. Known neurorestorative processes within the peri-infarct area were evaluated by histological and biochemical analyses at 30 days post-stroke. This study demonstrated that GH treatment improves motor function after stroke by 50%–60%, as assessed using the cylinder and grid walk tests. Furthermore, the observed functional improvements occurred in parallel with a reduction in brain tissue loss, as well as increased cell proliferation, neurogenesis, increased synaptic plasticity and angiogenesis within the peri-infarct area. These findings provide new evidence about the potential therapeutic effects of GH in stroke recovery.

Ischaemic and hypoxic conditioning: potential for protection of vital organs

NEW FINDINGS

What is the topic of this review? Remote ischaemic preconditioning (RIPC) and hypoxic preconditioning as novel therapeutic approaches for cardiac and neuroprotection. What advances does it highlight? There is improved understanding of mechanisms and signalling pathways associated with ischaemic and hypoxic preconditioning, and potential pitfalls with application of these therapies to clinical trials have been identified. Novel adaptations of preconditioning paradigms have also been developed, including intermittent hypoxia training, RIPC training and RIPC-exercise, extending their utility to chronic settings.

ABSTRACT

Myocardial infarction and stroke remain leading causes of death worldwide, despite extensive resources directed towards developing effective treatments. In this Symposium Report we highlight the potential applications of intermittent ischaemic and hypoxic conditioning protocols to combat the deleterious consequences of heart and brain ischaemia. Insights into mechanisms underlying the protective effects of intermittent hypoxia training are discussed, including the activation of hypoxia-inducible factor-1 and Nrf2 transcription factors, synthesis of antioxidant and ATP-generating enzymes, and a shift in microglia from pro- to anti-inflammatory phenotypes. Although there is little argument regarding the efficacy of remote ischaemic preconditioning (RIPC) in pre-clinical models, this strategy has not consistently translated into the clinical arena. This lack of translation may be related to the patient populations targeted thus far, and the anaesthetic regimen used in two of the major RIPC clinical trials. Additionally, we do not fully understand the mechanism through which RIPC protects the vital organs, and co-morbidities (e.g. hypercholesterolemia, diabetes) may interfere with its efficacy. Finally, novel adaptations have been made to extend RIPC to more chronic settings. One adaptation is RIPC-exercise (RIPC-X), an innovative paradigm that applies cyclical RIPC to blood flow restriction exercise (BFRE). Recent findings suggest that this novel exercise modality attenuates the exaggerated haemodynamic responses that may limit the use of conventional BFRE in some clinical settings. Collectively, intermittent ischaemic and hypoxic conditioning paradigms remain an exciting frontier for the protection against ischaemic injuries.

Therapeutic impact of rHuEPO on abnormal platelet APP, BACE 1, presenilin 1, ADAM 10 and Aβ expressions in chronic kidney disease patients with cognitive dysfunction like Alzheimer's disease: A pilot study

BACKGROUND

Cognitive dysfunction is reported to be a major cause of morbidity in chronic kidney disease (CKD). The senile plaques (SPs) in the brain are one of the most pathophysiological characteristics of cognitive dysfunction and its major constituent amyloid β (Aβ) released from amyloid precursor protein (APP) by β (BACE1) and γ (presenilin 1) secretases . Platelets contain more than 95% of the circulating APP and implicate as a candidate biomarker for cognitive decline. Recombinant human erythropoietin (rHuEPO) is a standard therapy for anemia in CKD and also acts as a neuroprotective agent. The aim of the study is to determine the impact of rHuEPO therapy on platelet APP processing in CKD with Cognitive Dysfunction.

METHODS

A total of 60 subjects comprising of 30 CKD without cognitive dysfunction and 30 CKD with cognitive dysfunction based on neuropsychological assessment. APP, BACE1, Presenilin 1, ADAM 10 (α secretase) and Aβ expressions in platelets were determined by western blotting and lipid peroxidation (LPO) in platelet rich plasma (PRP) was done by spectrophotometrically. The parameters were statistically compared with Alzheimer's disease (AD), Normocytic normochromic anemic and healthy subjects.

RESULTS

Significantly (p < 0.05) decreased APP, ADAM 10 while increased BACE1, Presenilin 1, Aβ and LPO were observed in CKD with cognitive dysfunction like AD subjects compared to other groups. The parameters were reassessed in CKD with cognitive dysfunction subjects after rHuEPO (100 IU/ kg, weekly twice, 6 months) therapy. All the parameters were retrieved significantly (p < 0.05) along with improved neuropsychological tests scoring after rHuEPO therapy.

CONCLUSIONS

This study demonstrated that rHuEPO is an effective neuroprotective agent in the context of CKD associated cognitive dysfunction and proved its clinical usefulness.

EPO improved neurologic outcome in rat pups late after traumatic brain injury

In adult rats, erythropoietin improved outcomes early and late after traumatic brain injury, associated with increased levels of Brain Derived Neurotrophic Factor. Using our model of pediatric traumatic brain injury, controlled cortical impact in 17-day old rats, we previously showed that erythropoietin increased hippocampal neuronal fraction in the first two days after injury. Erythropoietin also decreased activation of caspase3, an apoptotic enzyme modulated by Brain Derived Neurotrophic Factor, and improved Novel Object Recognition testing 14 days after injury. Data on long-term effects of erythropoietin on Brain Derived Neurotrophic Factor expression, histology and cognitive function after developmental traumatic brain injury are lacking. We hypothesized that erythropoietin would increase Brain Derived Neurotrophic Factor and improve long-term object recognition in rat pups after controlled cortical impact, associated with increased neuronal fraction in the hippocampus.

METHODS

Rats pups received erythropoietin or vehicle at 1, 24, and 48 h and 7 days after injury or sham surgery followed by histology at 35 days, Novel Object Recognition testing at adulthood, and Brain Derived Neurotrophic Factor measurements early and late after injury.

RESULTS

Erythropoietin improved Novel Object Recognition performance and preserved hippocampal volume, but not neuronal fraction, late after injury.

CONCLUSIONS

Improved object recognition in erythropoietin treated rats was associated with preserved hippocampal volume late after traumatic brain injury. Erythropoietin is approved to treat various pediatric conditions. Coupled with exciting experimental and clinical studies suggesting it is beneficial after neonatal hypoxic ischemic brain injury, our preliminary findings support further study of erythropoietin use after developmental traumatic brain injury.

Antioxidant therapies in traumatic brain injury: a review

Oxidative stress constitute one of the commonest mechanism of the secondary injury contributing to neuronal death in traumatic brain injury cases. The oxidative stress induced secondary injury blockade may be considered as to be a good alternative to improve the outcome of traumatic brain injury (TBI) treatment. Due to absence of definitive therapy of traumatic brain injury has forced researcher to utilize unconventional therapies and its roles investigated in the improvement of management and outcome in recent year. Antioxidant therapies are proven effective in many preclinical studies and encouraging results and the role of antioxidant mediaction may act as further advancement in the traumatic brain injury management it may represent aonr of newer moadlaity in neurosurgical aramamentorium, this kind of therapy could be a good alternative or adjuct to the previously established neuroprotection agents in TBI.

Effects of Quercetin and Mannitol on Erythropoietin Levels in Rats Following Acute Severe Traumatic Brain Injury

Objective

The aim of this study to investigate the normal values of erythropoietin (EPO) and neuroprotective effects of quercetin and mannitol on EPO and hematocrit levels after acute severe traumatic brain injury (TBI) in rat model.

Methods

A weight-drop impact acceleration model of TBI was used on 40 male Wistar rats. The animals were divided into sham (group I), TBI (group II), TBI+quercetin (50 mg/kg intravenously) (group III), and TBI+mannitol (1 mg/kg intravenously) (group IV) groups. The malondialdehyde, glutathione peroxidase, catalase, EPO, and hematocrit levels were measured 1 and 4 hour after injury. Two-way repeated measures analysis of variance and Tukey’s test were used for statistical analysis.

Results

The malondialdehyde levels decreased significantly after administration of quercetin and mannitol compared with those in group II. Catalase and glutathione peroxidase levels increased significantly in groups III and IV. Serum EPO levels decreased significantly after mannitol but not after quercetin administration. Serum hematocrit levels did not change significantly after quercetin and mannitol administration 1 hour after trauma. However, mannitol administration decreased serum hematocrit levels significantly after 4 hour.

Conclusion

This study suggests that quercetin may be a good alternative treatment for TBI, as it did not decrease the EPO levels.

G-CSF and cognitive dysfunction in elderly diabetic mice with cerebral small vessel disease: Preventive intervention effects and underlying mechanisms

AIMS

Although cognitive dysfunction is a common neurological complication in elderly patients with diabetes, the mechanisms underlying this relationship remain unclear, and effective preventive interventions have yet to be developed. Thus, this study investigated the preventive effects and mechanisms of action associated with granulocyte colony-stimulating factor (G-CSF) on cognitive dysfunction in elderly diabetic mice with cerebral small vessel disease.

METHODS

This study included 40 male db/db diabetic and wild-type (WT) mice that were categorized into the following four groups at the age of 3 weeks: db/db group (DG), db/db+G-CSF group (DGG), WT group (WG), and WT+G-CSF group (WGG). The mice were fed normal diets for 4 months and then given G-CSF (75 μg/kg) via intraperitoneal injections for 1 month. At 7.5 months of age, the cognitive abilities of the mice were assessed with the Y-maze test and the Social Choice Test; body weight, blood pressure (BP), and blood glucose measurements were obtained throughout the study. Brain imaging and blood oxygen level-dependent (BOLD) contrast imaging analyses were performed with a small animal magnetic resonance imaging (MRI) system, autophagosome levels were detected with a transmission electron microscope (TEM), hippocampal neurons were assessed with hematoxylin and eosin (HE) staining, and protein expressions and distributions were evaluated using immunohistochemistry and Western blot analyses.

RESULTS

(i) The body weight and blood glucose levels of the DG and DGG mice were significantly higher than those of the WG and WGG mice; (ii) social choice and spatial memory capabilities were significantly reduced in DG mice but were recovered by G-CSF in DGG mice; (iii) the MRI scans revealed multiple lacunar lesions and apparent hippocampal atrophy in the brains of DG mice, but G-CSF reduced the number of lacunar lesions and ameliorated hippocampal atrophy; (iv) the MRI-BOLD scans showed a downward trend in whole-brain activity and reductions in the connectivities of the hippocampus and amygdala with subcortical structures in DG mice, but G-CSF clearly improved the altered brain activity as well as the connectivity of the hippocampus in DGG mice; (v) HE staining revealed fewer neurons in the hippocampus in DG mice; (vi) TEM analyses revealed significantly fewer autophagosomes in the hippocampi of DG mice, but G-CSF did not increase these numbers; (vii) there were significant reductions in mechanistic target of rapamycin (mTOR) and LC3-phosphatidylethanolamine conjugate (LC3)-II/I levels in the hippocampi of DG mice, whereas p62 was upregulated, and G-CSF significantly enhanced the levels of Beclin1, mTOR, and LC-II/I in DGG mice; and (viii) G-CSF significantly reversed increases in nuclear factor κB (NF-κB) protein levels in DG but not in WG mice.

CONCLUSIONS

In this study, aged diabetic mice were prone to cognitive dysfunction and cerebral small vessel disease. However, administration of G-CSF significantly improved cognitive function in elderly db/db diabetic mice, and this change was likely related to the regulation of autophagy and NF-κB signaling pathways.

Erythropoietin: Endogenous Protection of Ischemic Brain

The human brain requires uninterrupted delivery of blood-borne oxygen and nutrients to sustain its function. Focal ischemia, particularly, ischemic stroke, and global ischemia imposed by cardiac arrest disrupt the brain's fuel supply. The resultant ATP depletion initiates a complex injury cascade encompassing intracellular Ca²⁺ overload, glutamate excitotoxicity, oxido-nitrosative stress, extracellular matrix degradation, and inflammation, culminating in neuronal and astroglial necrosis and apoptosis, neurocognitive deficits, and even death. Unfortunately, brain ischemia has proven refractory to pharmacological intervention. Many promising treatments afforded brain protection in animal models of focal and global ischemia, but failed to improve survival and neurocognitive recovery of stroke and cardiac arrest patients in randomized clinical trials. The culprits are the blood-brain barrier (BBB) that limits transferral of medications to the brain parenchyma, and the sheer complexity of the injury cascade, which presents a daunting array of targets unlikely to respond to monotherapies. Erythropoietin is a powerful neuroprotectant capable of interrupting multiple aspects of the brain injury cascade. Preclinical research demonstrates erythropoietin's ability to suppress glutamate excitotoxicity and intracellular Ca²⁺ overload, dampen oxidative stress and inflammation, interrupt the apoptotic cascade, and preserve BBB integrity. However, the erythropoietin dosages required to traverse the BBB and achieve therapeutically effective concentrations in the brain parenchyma impose untoward side effects. Recent discoveries that hypoxia induces erythropoietin production within the brain and that neurons, astroglia, and cerebrovascular endothelium harbor membrane erythropoietin receptors, raise the exciting prospect of harnessing endogenous erythropoietin to protect the brain from the ravages of ischemia-reperfusion.

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.

Chronic Histopathological and Behavioral Outcomes of Experimental Traumatic Brain Injury in Adult Male Animals

The purpose of this review is to survey the use of experimental animal models for studying the chronic histopathological and behavioral consequences of traumatic brain injury (TBI). The strategies employed to study the long-term consequences of TBI are described, along with a summary of the evidence available to date from common experimental TBI models: fluid percussion injury; controlled cortical impact; blast TBI; and closed-head injury. For each model, evidence is organized according to outcome. Histopathological outcomes included are gross changes in morphology/histology, ventricular enlargement, gray/white matter shrinkage, axonal injury, cerebrovascular histopathology, inflammation, and neurogenesis. Behavioral outcomes included are overall neurological function, motor function, cognitive function, frontal lobe function, and stress-related outcomes. A brief discussion is provided comparing the most common experimental models of TBI and highlighting the utility of each model in understanding specific aspects of TBI pathology. The majority of experimental TBI studies collect data in the acute postinjury period, but few continue into the chronic period. Available evidence from long-term studies suggests that many of the experimental TBI models can lead to progressive changes in histopathology and behavior. The studies described in this review contribute to our understanding of chronic TBI pathology.

Microglia in the TBI brain: The good, the bad, and the dysregulated

As the major cellular component of the innate immune system in the central nervous system (CNS) and the first line of defense whenever injury or disease occurs, microglia play a critical role in neuroinflammation following a traumatic brain injury (TBI). In the injured brain microglia can produce neuroprotective factors, clear cellular debris and orchestrate neurorestorative processes that are beneficial for neurological recovery after TBI. However, microglia can also become dysregulated and can produce high levels of pro-inflammatory and cytotoxic mediators that hinder CNS repair and contribute to neuronal dysfunction and cell death. The dual role of microglial activation in promoting beneficial and detrimental effects on neurons may be accounted for by their polarization state and functional responses after injury. In this review article we discuss emerging research on microglial activation phenotypes in the context of acute brain injury, and the potential role of microglia in phenotype-specific neurorestorative processes such as neurogenesis, angiogenesis, oligodendrogenesis and regeneration. We also describe some of the known molecular mechanisms that regulate phenotype switching, and highlight new therapeutic approaches that alter microglial activation state balance to enhance long-term functional recovery after TBI. An improved understanding of the regulatory mechanisms that control microglial phenotypic shifts may advance our knowledge of post-injury recovery and repair, and provide opportunities for the development of novel therapeutic strategies for TBI.

Harnessing the master transcriptional repressor REST to reciprocally regulate neurogenesis

Neurogenesis begins in embryonic development and continues at a reduced rate into adulthood in vertebrate species, yet the signaling cascades regulating this process remain poorly understood. Plasma membrane-initiated signaling cascades regulate neurogenesis via downstream pathways including components of the transcriptional machinery. A nuclear factor that temporally regulates neurogenesis by repressing neuronal differentiation is the repressor element 1 (RE1) silencing transcription (REST) factor. We have recently discovered a regulatory site on REST that serves as a molecular switch for neuronal differentiation. Specifically, C-terminal domain small phosphatase 1, CTDSP1, present in non-neuronal cells, maintains REST activity by dephosphorylating this site. Reciprocally, extracellular signal-regulated kinase, ERK, activated by growth factor signaling in neural progenitors, and peptidylprolyl cis/trans isomerase Pin1, decrease REST activity through phosphorylation-dependent degradation. Our findings further resolve the mechanism for temporal regulation of REST and terminal neuronal differentiation. They also provide new potential therapeutic targets to enhance neuronal regeneration after injury.

Wharton's Jelly Transplantation Improves Neurologic Function in a Rat Model of Traumatic Brain Injury

Traumatic brain injury (TBI), which can lead to disability, dysfunction, and even death, is a prominent health problem worldwide. Effective therapy for this serious and debilitating condition is needed. Human umbilical cord matrix, known as Wharton's jelly (WJ), provides a natural, interface scaffold that is enriched in mesenchymal stem cells. In this study, we tested the efficacy of WJ tissue transplantation in a weight-drop model of TBI in rats. WJ tissue was cultured and transplanted into the injury site 24 h after TBI. The modified neurologic severity score, body weight, brain edema, and lesion volume were evaluated at various time points after TBI. Cognitive behavior was assessed by the novel object recognition test and the Morris water maze test. Expression of brain-derived neurotrophic factor (BDNF) in the perilesional brain area was measured at day 14 after TBI. We found that WJ tissue transplantation lessened TBI-induced brain edema (day 3), reduced lesion volume (day 28), improved neurologic function (days 21-28), and promoted memory and cognitive recovery. Additionally, expression of BDNF mRNA and protein was higher in WJ tissue-treated rats than in sham-operated or vehicle-treated rats. These data suggest that WJ tissue transplantation can reduce TBI-induced brain injury and may have therapeutic potential for the treatment of TBI.

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.

Subacute intranasal administration of tissue plasminogen activator promotes neuroplasticity and improves functional recovery following traumatic brain injury in rats

Traumatic brain injury (TBI) is a major cause of death and long-term disability worldwide. To date, there are no effective pharmacological treatments for TBI. Recombinant human tissue plasminogen activator (tPA) is the effective drug for the treatment of acute ischemic stroke. In addition to its thrombolytic effect, tPA is also involved in neuroplasticity in the central nervous system. However, tPA has potential adverse side effects when administered intravenously including brain edema and hemorrhage. Here we report that tPA, administered by intranasal delivery during the subacute phase after TBI, provides therapeutic benefit. Animals with TBI were treated intranasally with saline or tPA initiated 7 days after TBI. Compared with saline treatment, subacute intranasal tPA treatment significantly 1) improved cognitive (Morris water maze test) and sensorimotor (footfault and modified neurological severity score) functional recovery in rats after TBI, 2) reduced the cortical stimulation threshold evoking ipsilateral forelimb movement, 3) enhanced neurogenesis in the dentate gyrus and axonal sprouting of the corticospinal tract originating from the contralesional cortex into the denervated side of the cervical gray matter, and 4) increased the level of mature brain-derived neurotrophic factor. Our data suggest that subacute intranasal tPA treatment improves functional recovery and promotes brain neurogenesis and spinal cord axonal sprouting after TBI, which may be mediated, at least in part, by tPA/plasmin-dependent maturation of brain-derived neurotrophic factor.

The efficacy of erythropoietin in treating experimental traumatic brain injury: a systematic review of controlled trials in animal models

OBJECT

Erythropoietin (EPO) shows promise as a neuroprotective agent in animal models of traumatic brain injury (TBI). However, clinical trials of the efficacy of EPO treatment in patients with TBI yield conflicting results. The authors conducted a systematic review and meta-analysis to assess the effect of EPO in experimental animal models of TBI, the goal being to inform the design of future clinical trials.

METHODS

The authors identified eligible studies by searching PubMed, Web of Science, MEDLINE, Embase, and Google Scholar in October 2013. Data were pooled using the random-effects model, and results were reported in terms of standardized mean difference. Statistical heterogeneity was examined using both I(2) and chi-square tests, and the presence of small study effects was investigated with funnel plots and Egger tests. In-depth analyses were performed for lesion volume and neurobehavioral outcome, and the studies' methodological quality was also evaluated.

RESULTS

Of a total of 290 studies, 13 found an effect of EPO on lesion volume and neurobehavioral outcome. Overall, the methodological quality of the studies was poor, and there was evidence of statistical heterogeneity among the publications as well as small-study effects. However, in-depth analyses showed statistically significant findings in favor of a beneficial effect of EPO after TBI.

CONCLUSIONS

Despite limitations of this systematic review that may have influenced the findings, the authors conclude that EPO might be beneficial in treating experimental TBI in terms of reducing lesion volume and improving neurobehavioral outcome. However, this review also indicates that more well-designed and well-reported animal studies are needed.

Cerebro-renal interactions: impact of uremic toxins on cognitive function

Cognitive impairment (CI) associated with chronic kidney disease (CKD) has received attention as an important problem in recent years. Causes of CI with CKD are multifactorial, and include cerebrovascular disease, renal anemia, secondary hyperparathyroidism, dialysis disequilibrium, and uremic toxins (UTs). Among these causes, little is known about the role of UTs. We therefore selected 21 uremic compounds, and summarized reports of cerebro-renal interactions associated with UTs. Among the compounds, uric acid, indoxyl sulfate, p-cresyl sulfate, interleukin 1-β, interleukin 6, TNF-α, and PTH were most likely to affect the cerebro-renal interaction dysfunction; however, sufficient data have not been obtained for other UTs. Notably, most of the data were not obtained under uremic conditions; therefore, the impact and mechanism of each UT on cognition and central nervous system in uremic state remains unknown. At present, impacts and mechanisms of UT effects on cognition are poorly understood. Clarifying the mechanisms and establishing novel therapeutic strategies for cerebro-renal interaction dysfunction is expected to be subject of future research.

Functional assessment of long-term deficits in rodent models of traumatic brain injury

Traumatic brain injury (TBI) ranks as the leading cause of mortality and disability in the young population worldwide. The annual US incidence of TBI in the general population is estimated at 1.7 million per year, with an estimated financial burden in excess of US$75 billion a year in the USA alone. Despite the prevalence and cost of TBI to individuals and society, no treatments have passed clinical trial to clinical implementation. The rapid expansion of stem cell research and technology offers an alternative to traditional pharmacological approaches targeting acute neuroprotection. However, preclinical testing of these approaches depends on the selection and characterization of appropriate animal models. In this article we consider the underlying pathophysiology for the focal and diffuse TBI subtypes, discuss the existing preclinical TBI models and functional outcome tasks used for assessment of injury and recovery, identify criteria particular to preclinical animal models of TBI in which stem cell therapies can be tested for safety and efficacy, and review these criteria in the context of the existing TBI literature. We suggest that 2 months post-TBI is the minimum period needed to evaluate human cell transplant efficacy and safety. Comprehensive review of the published TBI literature revealed that only 32% of rodent TBI papers evaluated functional outcome ≥1 month post-TBI, and only 10% evaluated functional outcomes ≥2 months post-TBI. Not all published papers that evaluated functional deficits at a minimum of 2 months post-TBI reported deficits; hence, only 8.6% of overall TBI papers captured in this review demonstrated functional deficits at 2 months or more postinjury. A 2-month survival and assessment period would allow sufficient time for differentiation and integration of human neural stem cells with the host. Critically, while trophic effects might be observed at earlier time points, it will also be important to demonstrate the sustainability of such an effect, supporting the importance of an extended period of in vivo observation. Furthermore, regulatory bodies will likely require at least 6 months survival post-transplantation for assessment of toxicology/safety, particularly in the context of assessing cell abnormalities.

Erythropoietin and the heart: physiological effects and the therapeutic perspective

Erythropoietin (Epo) has been thought to act exclusively on erythroid progenitor cells. The identification of Epo receptor (EpoR) in non-haematopoietic cells and tissues including neurons, astrocytes, microglia, immune cells, cancer cell lines, endothelial cells, bone marrow stromal cells, as well as cells of myocardium, reproductive system, gastrointestinal tract, kidney, pancreas and skeletal muscle indicates that Epo has pleiotropic actions. Epo shows signals through protein kinases, anti-apoptotic proteins and transcription factors. In light of interest of administering recombinant human erythropoietin (rhEpo) and its analogues for limiting infarct size and left ventricular (LV) remodelling after acute myocardial infarction (AMI) in humans, the foremost studies utilising rhEpo are reviewed. The putative mechanisms involved in Epo-induced cardioprotection are related to the antiapoptotic, anti-inflammatory and angiogenic effects of Epo. Thus, cardioprotective potentials of rhEpo are reviewed in this article by focusing on clinical applicability. An overview of non-haematopoietic Epo analogues, which are a reliable alternative to the classic EpoR agonists and may prevent undesired side effects, is also provided.

Erythropoietin mediates neurobehavioral recovery and neurovascular remodeling following traumatic brain injury in rats by increasing expression of vascular endothelial growth factor

Erythropoietin (EPO) improves functional recovery after traumatic brain injury (TBI). Here, we investigated the role of vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2) on EPO-induced therapeutic efficacy in rats after TBI. Young male Wistar rats were subjected to unilateral controlled cortical impact injury and then infused intracerebroventricularly with either a potent selective VEGFR2 inhibitor SU5416 or vehicle dimethyl sulfoxide. Animals from both groups received delayed EPO treatment (5,000 U/kg in saline) administered intraperitoneally daily at 1, 2, and 3 days post injury. TBI rats treated with saline administered intraperitoneally daily at 1, 2, and 3 days post injury served as EPO treatment controls. 5-bromo-2-deoxyuridine was administered to label dividing cells. Spatial learning and sensorimotor function were assessed using a modified Morris water maze test and modified neurological severity score, respectively. Animals were sacrificed at 4 days post injury for measurement of VEGF and VEGFR2 or 35 days post injury for evaluation of cell proliferation, angiogenesis and neurogenesis. EPO treatment promoted sensorimotor and cognitive functional recovery after TBI. EPO treatment increased brain VEGF expression and phosphorylation of VEGFR2. EPO significantly increased cell proliferation, angiogenesis and neurogenesis in the dentate gyrus after TBI. Compared to the vehicle, SU5416 infusion significantly inhibited phosphorylation of VEGFR2, cell proliferation, angiogenesis, and neurogenesis as well as abolished functional recovery in EPO-treated TBI rats. These findings indicate the VEGF/VEGFR2 activation plays an important role in EPO-mediated neurobehavioral recovery and neurovascular remodeling after TBI.

Neuroplasticity and the next wave of antidepressant strategies

Depression is a common chronic psychiatric disorder that is also often co-morbid with numerous neurological and immune diseases. Accumulating evidence indicates that disturbances of neuroplasticity occur with depression, including reductions of hippocampal neurogenesis and cortical synaptogenesis. Improper trophic support stemming from stressor-induced reductions of growth factors, most notably brain derived neurotrophic factor (BDNF), likely drives such aberrant neuroplasticity. We posit that psychological and immune stressors can interact upon a vulnerable genetic background to promote depression by disturbing BDNF and neuroplastic processes. Furthermore, the chronic and commonly relapsing nature of depression is suggested to stem from "faulty wiring" of emotional circuits driven by neuroplastic aberrations. The present review considers depression in such terms and attempts to integrate the available evidence indicating that the efficacy of current and "next wave" antidepressant treatments, whether used alone or in combination, is at least partially tied to their ability to modulate neuroplasticity. We particularly focus on the N-methyl-D-aspartate (NMDA) antagonist, ketamine, which already has well documented rapid antidepressant effects, and the trophic cytokine, erythropoietin (EPO), which we propose as a potential adjunctive antidepressant agent.

Comparison of the effects of erythropoietin and anakinra on functional recovery and gene expression in a traumatic brain injury model

The goal of this study was to compare the effects of two inflammatory modulators, erythropoietin (EPO) and anakinra, on functional recovery and brain gene expression following a cortical contusion impact (CCI) injury. Dosage regimens were designed to provide serum concentrations in the range obtained with clinically approved doses. Functional recovery was assessed using both motor and spatial learning tasks and neuropathological measurements conducted in the cortex and hippocampus. Microarray-based transcriptional profiling was used to determine the effect on gene expression at 24 h, 72 h, and 7 days post-CCI. Ingenuity Pathway Analysis was used to evaluate the effect on relevant functional categories. EPO and anakinra treatment resulted in significant changes in brain gene expression in the CCI model demonstrating acceptable brain penetration. At all three time points, EPO treatment resulted in significantly more differentially expressed genes than anakinra. For anakinra at 24 h and EPO at 24 h, 72 h, and 7 days, the genes in the top 3 functional categories were involved in cellular movement, inflammatory response and cell-to-cell signaling. For EPO, the majority of the genes in the top 10 canonical pathways identified were associated with inflammatory and immune signaling processes. This was true for anakinra only at 24 h post-traumatic brain injury (TBI). The immunomodulation effects of EPO and anakinra did not translate into positive effects on functional behavioral and lesion studies. Treatment with either EPO or anakinra failed to induce significant beneficial effects on recovery of function or produce any significant effects on the prevention of injury induced tissue loss at 30 days post-injury. In conclusion, treatment with EPO or anakinra resulted in significant effects on gene expression in the brain without affecting functional outcome. This suggests that targeting these inflammatory processes alone may not be sufficient for preventing secondary injuries after TBI.

Erythropoietin in the neurology ICU

OPINION STATEMENT

Erythropoietin (EPO) is an approved drug that is used in the treatment of chronic anemia associated with chronic renal failure. In the Neuro ICU, there are 2 potential uses for treatment with EPO. Anemia is common in patients with acute neurological disorders and may be a cause of secondary insults. Studies of EPO to treat anemia associated with critical illness have not conclusively shown a beneficial risk/benefit ratio. The relatively small reduction in transfusion requirement with EPO in critically ill patients is likely due to the 7-10 days required to see an effect of EPO on hematocrit. For these reasons, EPO is not recommended to treat anemia of critical illness. Neuroprotection is the other potential use for EPO in the Neuro ICU. Many experimental studies demonstrate neuroprotective effects with EPO in a variety of acute neurological disorders. To date, no clinical studies have confirmed beneficial effects of EPO on neurological outcome although some studies have suggested a reduction in mortality rate in trauma patients treated with EPO. Additional clinical studies are needed before EPO administration can be recommended for cytoprotection in neurological disorders.

Neuroprotective and neurorestorative effects of thymosin β4 treatment following experimental traumatic brain injury

Traumatic brain injury (TBI) remains a leading cause of mortality and morbidity worldwide. No effective pharmacological treatments are available for TBI because all phase II/III TBI clinical trials have failed. This highlights a compelling need to develop effective treatments for TBI. Endogenous neurorestoration occurs in the brain after TBI, including angiogenesis, neurogenesis, synaptogenesis, oligodendrogenesis, and axonal remodeling, which may be associated with spontaneous functional recovery after TBI. However, the endogenous neurorestoration following TBI is limited. Treatments amplifying these neurorestorative processes may promote functional recovery after TBI. Thymosin beta 4 (Tβ4) is the major G-actin-sequestering molecule in eukaryotic cells. In addition, Tβ4 has other properties including antiapoptosis and anti-inflammation, promotion of angiogenesis, wound healing, stem/progenitor cell differentiation, and cell migration and survival, which provide the scientific foundation for the corneal, dermal, and cardiac wound repair multicenter clinical trials. Here, we describe Tβ4 as a neuroprotective and neurorestorative candidate for treatment of TBI.

Microarray-based gene expression analysis of an animal model for closed head injury

OBJECTIVE

Traumatic brain injury (TBI) is a major cause of death and disability in both children and the elderly. Mortality from TBI is said account for 1-2% of all deaths. One-third to one-half of all traumatic deaths is due to head injury. Of those who survive, the majority is left with significant disabilities, including 3% who remain in a vegetative state and only approximately 30% who make a good recovery. Microarray studies and other genomic techniques facilitate the discovery of new targets for the treatment of diseases, which aids in drug development, immunotherapeutics and gene therapy. Gene expression profiling or microarray analysis enables the measurement of thousands of genes in a single RNA sample.

METHODS

In this study, adult Wistar-albino rats underwent TBI using a trauma device. Brain tissues and blood samples were taken for gene expression at 1, 12 and 48 h post-trauma and were then analysed via microarray. Total RNA was isolated using an RNeasy Mini Kit (QIAGEN-Sample & Assay Technologies, Hilden, Germany) and tested using a 2100 Bioanalyzer (Agilent Technologies, Palo Alto, CA). Overall changes in gene expression were evaluated using Agilent Whole Rat Genome 4 × 44 K oligonucleotide arrays and analysed with GeneSpring (GeneSpring 6.1, Silicon Genetics, Redwood City, CA) software. Only genes with a signal-to-noise ratio of above 2 in the experiments were included in the statistical analysis.

RESULTS

ANOVA (p<0.05) was performed to identify differentially expressed probe sets. Additional filtering (minimum 2-fold change) was applied to extract the most differentially expressed genes based on the study groups (Control vs. 1st hour, Control vs. 12th hour, Control vs. 48th hour). Differentially expressed genes were detected via microarray analysis. A gene interaction-based network investigation of the genes that were identified via traditional microarray data analysis describes a significantly relevant gene network that includes the C1ql2, Cbnl, Sdc1, Bdnf, MMP9, and Cd47 genes, which were differentially expressed compared with the controls.

CONCLUSIONS

In this study, we will review the current understanding of the genetic susceptibility of TBI with microarrays. Our results highlight the importance of genes that control the response of the brain to injury as well as the suitability of microarrays for identifying specific targets for further study.

A review of neuroprotection pharmacology and therapies in patients with acute traumatic brain injury

Traumatic brain injury (TBI) affects 1.6 million Americans annually. The injury severity impacts the overall outcome and likelihood for survival. Current treatment of acute TBI includes surgical intervention and supportive care therapies. Treatment of elevated intracranial pressure and optimizing cerebral perfusion are cornerstones of current therapy. These approaches do not directly address the secondary neurological sequelae that lead to continued brain injury after TBI. Depending on injury severity, a complex cascade of processes are activated and generate continued endogenous changes affecting cellular systems and overall outcome from the initial insult to the brain. Homeostatic cellular processes governing calcium influx, mitochondrial function, membrane stability, redox balance, blood flow and cytoskeletal structure often become dysfunctional after TBI. Interruption of this cascade has been the target of numerous pharmacotherapeutic agents investigated over the last two decades. Many agents such as selfotel, pegorgotein (PEG-SOD), magnesium, deltibant and dexanabinol were ineffective in clinical trials. While progesterone and ciclosporin have shown promise in phase II studies, success in larger phase III, randomized, multicentre, clinical trials is pending. Consequently, no neuroprotective treatment options currently exist that improve neurological outcome after TBI. Investigations to date have extended understanding of the injury mechanisms and sites for intervention. Examination of novel strategies addressing both pathological and pharmacological factors affecting outcome, employing novel trial design methods and utilizing biomarkers validated to be reflective of the prognosis for TBI will facilitate progress in overcoming the obstacles identified from previous clinical trials.

Protective effects of hydrogen-rich saline in a rat model of traumatic brain injury via reducing oxidative stress

BACKGROUND

Hydrogen gas (H(2)) has been considered as a novel antioxidant to selectively reduce the toxic reactive oxygen species (ROS) such as hydroxyl radical (•OH) without affecting the other signal ROS. Our recent study shows that H(2) inhalation is beneficial to traumatic brain injury (TBI) via reducing oxidative stress. In contrast to H(2), hydrogen-rich saline (HS) may be more suitable for clinical application. The present study was designed to investigate whether HS has a protective effect against TBI via reducing oxidative stress in rats.

METHODS

TBI model was induced by controlled cortical impact injury. Different dosages of HS were intraperitoneally administered at 5 min after TBI operation. We then measured the brain edema, blood-brain barrier (BBB) breakdown, neurological dysfunction and injury volume in all animals. In addition, the oxidative products and antioxidant enzymes in brain tissues were detected.

RESULTS

TBI-challenged rats exhibited significant brain injuries characterized by the increase of BBB permeability, brain edema, and lesion volume as well as neurological dysfunction, which were dose-dependently ameliorated by HS treatment. Moreover, we found that HS treatment increased the endogenous antioxidant enzymatic activities and decreased the oxidative product levels in brain tissues of TBI-challenged rats.

CONCLUSION

Hydrogen-rich saline can exert a protective effect against TBI via reducing oxidative stress. Molecular hydrogen may be a more effective therapeutic strategy for TBI patients.

In vitro models of traumatic brain injury

In vitro models of traumatic brain injury (TBI) are helping elucidate the pathobiological mechanisms responsible for dysfunction and delayed cell death after mechanical stimulation of the brain. Researchers have identified compounds that have the potential to break the chain of molecular events set in motion by traumatic injury. Ultimately, the utility of in vitro models in identifying novel therapeutics will be determined by how closely the in vitro cascades recapitulate the sequence of cellular events that play out in vivo after TBI. Herein, the major in vitro models are reviewed, and a discussion of the physical injury mechanisms and culture preparations is employed. A comparison between the efficacy of compounds tested in vitro and in vivo is presented as a critical evaluation of the fidelity of in vitro models to the complex pathobiology that is TBI. We conclude that in vitro models were greater than 88% predictive of in vivo results.

Erythropoietin in brain development and beyond

Erythropoietin is known as the requisite cytokine for red blood cell production. Its receptor, expressed at a high level on erythroid progenitor/precursor cells, is also found on endothelial, neural, and other cell types. Erythropoietin and erythropoietin receptor expression in the developing and adult brain suggest their possible involvement in neurodevelopment and neuroprotection. During ischemic stress, erythropoietin, which is hypoxia inducible, can contribute to brain homeostasis by increasing red blood cell production to increase the blood oxygen carrying capacity, stimulate nitric oxide production to modulate blood flow and contribute to the neurovascular response, or act directly on neural cells to provide neuroprotection as demonstrated in culture and animal models. Clinical studies of erythropoietin treatment in stroke and other diseases provide insight on safety and potential adverse effects and underscore the potential pleiotropic activity of erythropoietin. Herein, we summarize the roles of EPO and its receptor in the developing and adult brain during health and disease, providing first a brief overview of the well-established EPO biology and signaling, its hypoxic regulation, and role in erythropoiesis.

Progesterone increases circulating endothelial progenitor cells and induces neural regeneration after traumatic brain injury in aged rats

Vascular remodeling plays a key role in neural regeneration in the injured brain. Circulating endothelial progenitor cells (EPCs) are a mediator of the vascular remodeling process. Previous studies have found that progesterone treatment of traumatic brain injury (TBI) decreases cerebral edema and cellular apoptosis and inhibits inflammation, which in concert promote neuroprotective effects in young adult rats. However, whether progesterone treatment regulates circulating EPC level and fosters vascular remodeling after TBI have not been investigated. In this study, we hypothesize that progesterone treatment following TBI increases circulating EPC levels and promotes vascular remodeling in the injured brain in aged rats. Male Wistar 20-month-old rats were subjected to a moderate unilateral parietal cortical contusion injury and were treated with or without progesterone (n=54/group). Progesterone was administered intraperitoneally at a dose of 16mg/kg at 1 h post-TBI and was subsequently injected subcutaneously daily for 14 days. Neurological functional tests and immnunostaining were performed. Circulating EPCs were measured by flow cytometry. Progesterone treatment significantly improved neurological outcome after TBI measured by the modified neurological severity score, Morris Water Maze and the long term potentiation in the hippocampus as well as increased the circulating EPC levels compared to TBI controls (p<0.05). Progesterone treatment also significantly increased CD34 and CD31 positive cell number and vessel density in the injured brain compared to TBI controls (p<0.05). These data indicate that progesterone treatment of TBI improves multiple neurological functional outcomes, increases the circulating EPC level, and facilitates vascular remodeling in the injured brain after TBI in aged rats.

Promises and pitfalls in erythopoietin-mediated tissue protection: are nonerythropoietic derivatives a way forward?

The essential biological role of erythropoietin (EPO) in maintaining erythrocyte mass has been well understood for many years. Although EPO is required for the maturation of red cells, it also has strong procoagulant effects on the vascular endothelium and platelets, which limit erythrocyte losses after hemorrhage. Like other members of the type 1 cytokine superfamily, EPO has multiple biological activities. For the past 10 years, multiple investigators have shown that EPO acts as a locally produced antagonist of proinflammatory cytokines that are generated by the innate immune response in response to infection, trauma, or metabolic stress. Specifically, EPO inhibits apoptosis of cells surrounding a locus of injury, reduces the influx of inflammatory cells, and recruits tissue-specific stem cells and endothelial progenitor cells. Available evidence suggests that these multiple, nonerythropoietic effects of EPO are mediated by a tissue protective receptor (TPR) that is distinct from the homodimeric receptor responsible for erythropoiesis. Notably, activation of the TPR requires a higher concentration of EPO than is needed for maximal erythropoiesis. Unfortunately, these higher concentrations of EPO also stimulate hematopoietic and procoagulant pathways, which can cause adverse effects and, therefore, potentially limit the clinical use of EPO for tissue protection. To circumvent these problems, the EPO molecule has been successfully modified in a variety of ways to interact only with the TPR. Early clinical experience has shown that these compounds appear to be safe, and proof of concept trials are ready to begin.

The potential role of JAK2/STAT3 pathway on the anti-apoptotic effect of recombinant human erythropoietin (rhEPO) after experimental traumatic brain injury of rats

Previous studies indicate that administration of recombinant human erythropoietin (rhEPO) protects cortical neurons following traumatic brain injury (TBI). The mechanisms of rhEPO's neuroprotection are complex and interacting, including anti-apoptosis. Here we aim to demonstrate the role of janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) pathway on the anti-apoptotic effect of rhEPO in Feeney free falling TBI model. Activation of JAK2/STAT3 in pericontusional cortex was analyzed among rats in Sham, TBI, TBI+rhEPO, TBI+rhEPO+AG490 groups (rhEPO: 5000 U/kg day; JAK2 inhibitor AG490: 5 mg/kg day, intraperitoneal) through Western blotting, electrophoretic mobility shift assay. Bcl-2 and Bcl-xl expression (Q-PCR, Western blotting) and cell apoptosis (TUNEL) in pericontusional cortex were also detected in each group. As a result, we found that TBI could activate JAK2 and STAT3, and increase cell apoptosis in pericontusional cortex. RhEPO enhanced the expression of p-JAK2 and p-STAT3, up-regulated the mRNA and protein levels of Bcl-2 and Bcl-xl, followed by increased cell survival. Moreover, AG490 attenuated rhEPO's neuroprotection by down-regulating rhEPO-induced activation of JAK2/STAT3, and inhibiting Bcl-2 and Bcl-xl. These results suggest the essential role of JAK2/STAT3 pathway on the anti-apoptotic benefit of post-TBI rhEPO treatment.

Dose-dependent neurorestorative effects of delayed treatment of traumatic brain injury with recombinant human erythropoietin in rats

OBJECT

Delayed (24 hours postinjury) treatment with erythropoietin (EPO) improves functional recovery following experimental traumatic brain injury (TBI). In this study, the authors tested whether therapeutic effects of delayed EPO treatment for TBI are dose dependent in an attempt to establish an optimal dose paradigm for the delayed EPO treatment.

METHODS

Experimental TBI was performed in anesthetized young adult male Wistar rats using a controlled cortical impact device. Sham animals underwent the same surgical procedure without injury. The animals (8 rats/group) received 3 intraperitoneal injections of EPO (0, 1000, 3000, 5000, or 7000 U/kg body weight, at 24, 48, and 72 hours) after TBI. Sensorimotor and cognitive functions were assessed using a modified neurological severity score and foot fault test, and Morris water maze tests, respectively. Animals were killed 35 days after injury, and the brain sections were stained for immunohistochemical analyses.

RESULTS

Compared with the saline treatment, EPO treatment at doses from 1000 to 7000 U/kg did not alter lesion volume but significantly reduced hippocampal neuron loss, enhanced angiogenesis and neurogenesis in the injured cortex and hippocampus, and significantly improved sensorimotor function and spatial learning. The animals receiving the medium dose of 5000 U/kg exhibited a significant improvement in histological and functional outcomes compared with the lower or higher EPO dose groups.

CONCLUSIONS

These data demonstrate that delayed (24 hours postinjury) treatment with EPO provides dose-dependent neurorestoration, which may contribute to improved functional recovery after TBI, implying that application of an optimal dose of EPO is likely to increase successful preclinical and clinical trials for treatment of TBI.

Effect of erythropoietin on the expression of HIF-1 and iNOS in retina in chronic ocular hypertension rats

AIM

To research the effect of erythropoietin (EPO) to the HIF-1\iNOS signal transduction path in retina in chronic ocular hypertension rat.

METHODS

One hundred and twenty Wistar rats were divided into 12 groups randomly. Two episcleral veins were coagulated unilaterally in rats with electric coagulator to establish the glaucoma model. PT-PCR and Western Blot analysis were used to examine the expression of Caspase-9 genes in retina. And the changes of ERG-b wave before and after were detected using EPO.

RESULTS

In EPO drug treatment group, the amplitude of ERG-b wave of retina restored remarkably. There was significant difference between two groups (P<0.05). The expressions of HIF-1\iNOS mRNA and protein in EPO drug treatment group were weakened remarkably. It was statistically different compared with the non-drug treatment group.

CONCLUSION

One of protect mechanisms of EPO to injured retina caused by chronic intraocular hypertension is through HIF-1\iNOS signal conduct path.

Erythropoietin promotes neurovascular remodeling and long-term functional recovery in rats following traumatic brain injury

Erythropoietin (EPO) improves functional recovery after traumatic brain injury (TBI). This study was designed to investigate long-term (3 months) effects of EPO on brain remodeling and functional recovery in rats after TBI. Young male Wistar rats were subjected to unilateral controlled cortical impact injury. TBI rats were divided into the following groups: (1) saline group (n=7); (2) EPO-6h group (n=8); and (3) EPO-24h group (n=8). EPO (5000 U/kg in saline) was administered intraperitoneally at 6h, and 1 and 2 days (EPO-6h group) or at 1, 2, and 3 days (EPO-24h group) postinjury. Neurological function was assessed using a modified neurological severity score, footfault and Morris water maze tests. Animals were sacrificed at 3 months after injury and brain sections were stained for immunohistochemical analyses. Compared to the saline, EPO-6h treatment significantly reduced cortical lesion volume, while EPO-24h therapy did not affect the lesion volume (P<0.05). Both the EPO-6h and EPO-24h treatments significantly reduced hippocampal cell loss (P<0.05), promoted angiogenesis (P<0.05) and increased endogenous cellular proliferation (BrdU-positive cells) in the injury boundary zone and hippocampus (P<0.05) compared to saline controls. Significantly enhanced neurogenesis (BrdU/NeuN-positive cells) was seen in the dentate gyrus of both EPO groups compared to the saline group. Both EPO treatments significantly improved long-term sensorimotor and cognitive functional recovery after TBI. In conclusion, the beneficial effects of posttraumatic EPO treatment on injured brain persisted for at least 3 months. The long-term improvement in functional outcome may in part be related to the neurovascular remodeling induced by EPO.

Improved cerebrovascular function and reduced histological damage with darbepoietin alfa administration after cortical impact injury in rats

Darbepoetin alfa (darbEpo) is an erythropoietic glycoprotein that activates the erythropoietin receptor. The aim of our study was to determine whether darbEpo is neuroprotective in a cortical impact injury (CII) model and to determine the characteristics of dose response and time window. To better understand the vascular mechanism of darbEpo neuroprotection, the reactivity of cerebral blood flow (CBF) to l-arginine administration was also studied. Rats were given saline or darbEpo from 2.5 to 50 μg/kg at 5 min after CII or a dose of 25 μg/kg darbEpo at times ranging from 5 min to 24 h after CII. Histological assessment was determined 2 weeks after a severe CII. Other rats were given either darbEpo (25 μg/kg) or saline daily for 3 days before injury. Five minutes after severe CII, they were given either l-arginine or d-arginine. Hemodynamic variables were monitored for 2 h after injury. In the dose-response study, darbEpo in doses of 25 and 50 μg/kg significantly reduced contusion volume from 39.1 ± 6.7 to 8.1 ± 3.1 and 11.2 ± 6.0 mm(3), respectively. In the time window study, darbEpo reduced contusion volume when given in a dose of 25 μg/kg at 5 min to 6 h after the impact injury. In animals pretreated with darbEpo, the CBF response to l-arginine was significantly greater than in the animals pretreated with saline. These data demonstrate that darbEpo has neuroprotective effects in traumatic brain injury in a dose- and time-dependent manner and that vascular effects of darbEpo may have a role in neuroprotection.

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.

Neurorestorative treatments for traumatic brain injury

Traumatic brain injury (TBI) remains a major cause of death and permanent disability worldwide, especially in children and young adults. A total of 1.5 million people experience head trauma each year in the United States, with an annual economic cost exceeding $56 billion. Unfortunately, almost all Phase III TBI clinical trials have yet to yield a safe and effective neuroprotective treatment, raising questions regarding the use of neuroprotective strategies as the primary therapy for acute brain injuries. Recent preclinical data suggest that neurorestorative strategies that promote angiogenesis (formation of new blood vessels from pre-existing endothelial cells), axonal remodeling (axonal sprouting and pruning), neurogenesis (generation of new neurons) and synaptogenesis (formation of new synapses) provide promising opportunities for the treatment of TBI. This review discusses select cell-based and pharmacological therapies that activate and amplify these endogenous restorative brain plasticity processes to promote both repair and regeneration of injured brain tissue and functional recovery after TBI.

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.

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.

Sprouting of corticospinal tract axons from the contralateral hemisphere into the denervated side of the spinal cord is associated with functional recovery in adult rat after traumatic brain injury and erythropoietin treatment

Erythropoietin (EPO) promotes functional recovery after traumatic brain injury (TBI). This study was designed to investigate whether EPO treatment promotes contralateral corticospinal tract (CST) plasticity in the spinal cord in rats after TBI. Biotinylated dextran amine (BDA) was injected into the right sensorimotor cortex to anterogradely label the CST. TBI was induced by controlled cortical impact over the left parietal cortex immediately after BDA injections. EPO (5000 U/kg) or saline was administered intraperitoneally at Days 1, 2, and 3 post-injury. Neurological function was assessed using a modified neurological severity score (mNSS) and footfault tests. Animals were sacrificed 35 days after injury and brain sections stained for histological analysis. Compared to the saline treatment, EPO treatment significantly improved sensorimotor functional outcome (lower mNSS and reduced footfaults) from Days 7 to 35 post-injury. TBI alone significantly stimulated contralateral CST axon sprouting toward the denervated gray matter of the cervical and lumbar spinal cord; however, EPO treatment further significantly increased the axon sprouting in TBI rats although EPO treatment did not significantly affect axon sprouting in sham animals. The contralesional CST sprouting was highly and positively correlated with sensorimotor recovery after TBI. These data demonstrate that CST fibers originating from the contralesional intact cerebral hemisphere are capable of sprouting into the denervated spinal cord after TBI and EPO treatment, which may at least partially contribute to functional recovery.

Beneficial effects of hydrogen gas in a rat model of traumatic brain injury via reducing oxidative stress

Traumatic brain injury (TBI) is a leading cause of mortality and disability among the young population. It has been shown that hydrogen gas (H(2)) exerts a therapeutic antioxidant activity by selectively reducing hydroxyl radical (OH, the most cytotoxic ROS). Recently, we have found that H(2) inhalation significantly improved the survival rate and organ damage of septic mice. In the present study, we investigated the effectiveness of H(2) therapy on brain edema, blood-brain barrier (BBB) breakdown, neurological dysfunction and injury volume in TBI-challenged rats. In addition, we investigated the effects of H(2) treatment on the changes of oxidative products and antioxidant enzymes in brain tissue of TBI-challenged rats. Hydrogen treatment was given by exposure to 2% H(2) from 5 min to 5h after sham or TBI operation, respectively. Here, we found that TBI-challenged rats showed significant brain injuries characterized by the increase of BBB permeability, brain edema and lesion volume as well as neurological dysfunction, which was significantly attenuated by 2% H(2) treatment. In addition, we found that the decrease of oxidative products and the increase of endogenous antioxidant enzymatic activities in the brain tissue may be associated with the protective effects of H(2) treatment in TBI-challenged rats. The present study supports that H(2) inhalation may be a more effective therapeutic strategy for patients with TBI.

Neuropsychiatric complications of chronic kidney disease

Evidence is emerging that cognitive impairment, delirium and depression are very common in patients with renal disease. All of these conditions are associated with prolonged hospitalization and an increased risk of mortality. A good understanding of these conditions is key to their prevention, early intervention and management. This Review summarizes the clinical features of various forms of cognitive dysfunction that occur in individuals with renal disease and describes the evidence for the high burden of disease in such patients.