Erythropoietin and Neonatal Neuroprotection

Pleiotropic effects of Erythropoietin. Influence of Erythropoietin on processes of mesenchymal stem cells differentiation

Structure and synthesis of Erythropoietin: Erythropoietin (EPO) is a glycoprotein hormone.

Recombinant Erythropoietin (Epoetin): Human recombinant erythropoietin is characterised as a factor which stimulates differentiation and proliferation of erythroid precursor cells, and as a tissue protective factor.

Anti-ischemic effects of recombinant Erythropoietin: Erythropoietin is one of the most perspective humoral agents which are involved in the preconditioning phenomenon.

Erythropoietin receptors and signal transduction pathways: Erythropoietin effects on cells through their interconnection with erythropoietin receptors, which triggers complex intracellular signal cascades, such as JAK2/STAT signaling pathway, phosphatidylinositol 3-kinase (PI3K), protein kinase C, mitogen-activated protein kinase (MAPK), and nuclear factor (NF)-κB signaling pathways.

Mechanisms of the effect of Erythropoietin on hematopoietic and non-hematopoietic cells and tissues: In addition to regulation of haemopoiesis, erythropoietin mediates bone formation as it has an effect on hematopoietic stem cells and osteoblastic niche, and this illustrates connection between the processes of haematopoiesis and osteopoiesis which take place in the red bone marrow.

The effect of Erythropoietin on mesenchymal stem cells and process of bone tissue formation: Erythropoietin promotes mesenchymal stem cells proliferation, migration and differentiation in osteogenic direction. The evidence of which is expression of bone phenotype by cells under the influence of EPO, including activation of bone specific transcription factors Runx2, osteocalcin and bone sialoprotein.

Conclusion: Erythropoietin has a pleiotropic effect on various types of cells and tissues. But the mechanisms which are involved in the process of bone tissue restoration via erythropoietin are still poorly understood.

Short-, Mid-, and Long-Term Effect of Granulocyte Colony-Stimulating Factor/Stem Cell Factor and Fms-Related Tyrosine Kinase 3 Ligand Evaluated in an In Vivo Model of Hypoxic-Hyperoxic Ischemic Neonatal Brain Injury

Hematopoietic growth factors are considered to bear neuroprotective potential. We have previously shown that delayed treatment with granulocyte colony-stimulating factor (G-CSF)/stem cell factor (SCF) and Fms-related tyrosine kinase 3 ligand (FL) ameliorates excitotoxic neonatal brain injury. The effect of these substances in combined-stressor neonatal brain injury models more closely mimicking clinical conditions has not been investigated. The aim of this study was to assess the short-, mid-, and long-term neuroprotective potential of G-CSF/SCF and FL in a neonatal model of hypoxic-hyperoxic ischemic brain injury. Five-day-old (P5) CD-1 mice were subjected to unilateral common carotid artery ligation and subsequent alternating periods of hypoxia and hyperoxia for 65 minutes. Sixty hours after injury, pups were randomly assigned to intraperitoneal treatment with (i) G-CSF (200 μg/kg)/SCF (50 μg/kg), (ii) FL (100 μg/kg), or (iii) vehicle every 24 hours for three or five consecutive days. Histopathological and functional outcomes were evaluated on P10, P18, and P90. Baseline outcome parameters were established in sham-treated and healthy control animals. Gross brain injury did not significantly differ between treatment groups at any time point. On P10, caspase-3 activation and caspase-independent apoptosis were similar between treatment groups; cell proliferation and the number of BrdU-positive vessels did not differ on P18 or P90. Neurobehavioral assessment did not reveal significant differences between treatment groups in accelerod performance, open field behavior, or novel object recognition capacity on P90. Turning behavior was more frequently observed in G-CSF/SCF- and FL-treated animals. No sex-specific differences were detected in any outcome parameter evaluated. In hypoxic-hyperoxic ischemic neonatal brain injury, G-CSF/SCF and FL treatment does not convey neuroprotection. Prior to potential clinical use, meticulous assessment of these hematopoietic growth factors is mandated.

The Potential Role of Ferroptosis in Neonatal Brain Injury

Ferroptosis is an iron-dependent form of cell death that is characterized by early lipid peroxidation and different from other forms of regulated cell death in terms of its genetic components, specific morphological features, and biochemical mechanisms. Different initiation pathways of ferroptosis have been reported, including inhibition of system X_c ^-, inactivation of glutathione-dependent peroxidase 4, and reduced glutathione levels, all of which ultimately promote the production of reactive oxygen species, particularly through enhanced lipid peroxidation. Although ferroptosis was first described in cancer cells, emerging evidence now links mechanisms of ferroptosis to many different diseases, including cerebral ischemia and brain hemorrhage. For example, neonatal brain injury is an important cause of developmental impairment and of permanent neurological deficits, and several types of cell death, including iron-dependent pathways, have been detected in the process of neonatal brain damage. Iron chelators and erythropoietin have both shown neuroprotective effects against neonatal brain injury. Here, we have summarized the potential relation between ferroptosis and neonatal brain injury, and according therapeutic intervention strategies.

Erythropoietin Prevents Anemia and Transfusions in Extremely Premature Lambs Supported by an EXTrauterine Environment for Neonatal Development (EXTEND)

BACKGROUND

We recently developed an EXTrauterine Environment for Neonatal Development (EXTEND) that provides physiologic support for premature lambs. Here, we assess the efficacy of exogenous erythropoietin (EPO) to prevent anemia and transfusions on EXTEND.

MATERIALS AND METHODS

Lambs were cannulated at 0.7 gestation and supported on EXTEND for up to 4 weeks. The lambs were divided into three groups: (1) No EPO, (2) Low EPO (300 U kg-1 per day), and (3) High EPO (800 U kg-1 per day). Daily hematocrit and weekly complete blood count were assessed.

RESULTS

The mean percentage change in hematocrit from baseline was significantly different between the groups (No EPO -23.6 ± 7.8% vs. Low EPO -16.6 ± 6.4% vs. High EPO +2.6 ± 6.6%; p = 0.02). This occurred despite a greater median number of blood transfusions in the No EPO group (5 vs. 1 vs. 0; p = 0.02). EPO administration was associated with a higher mean corpuscular volume (MCV; p < 0.01) and reticulocyte count (p = 0.02). The High EPO group was comparable to in utero control fetuses with respect to hematocrit (p = 0.49), MCV (p = 0.24), and reticulocyte count (p = 0.68).

CONCLUSIONS

EPO (800 U kg-1 per day) prevents anemia, eliminates transfusions, and restores normal red blood cell indices in premature lambs supported by EXTEND.

Intranasal breast milk for premature infants with severe intraventricular hemorrhage-an observation

For nasal application of neurotrophins and mesenchymal stem cells, successful delivery to the brain and therapeutic effects are known from experimental data in animals. Human breast milk contains neurotrophins and stem cells, but gavage tube feeding in preterm infants bypasses the naso-oropharynx. This is a first exploration on additional nasal breast milk and neuromorphological outcome after severe neonatal brain injury. We present a retrospective summary of 31 very low birth weight preterm infants with intraventricular hemorrhage °3/4 from one third-level neonatal center. All were breast milk fed. Sixteen infants additionally received nasal drops of fresh breast milk daily with informed parental consent for at least 28 days. Cerebral ultrasound courses were reviewed by a pediatric radiologist blinded to the intervention. The main outcome measure was severity of porencephalic defects before discharge. Clinical covariates were comparable in both groups. With nasal breast milk, a trend to a lower incidence for severe porencephalic defects (21% vs. 58%) was detected. Incidences were lower for progressive ventricular dilatation (71% vs. 91%) and surgery for posthemorrhagic hydrocephalus (50% vs. 67%).Conclusion: The hypothesis is generated that early intranasal application of breast milk could have a beneficial effect on neurodevelopment in preterm infants. Controlled investigation is needed. What is Known: • Successful delivery to the brain and therapeutic effects are known for nasal application of neurotrophins and mesenchymal stem cells from experimental data in animal studies. • Human breast milk contains neurotrophins and stem cells, but gavage tube feeding in preterm infants bypasses the naso-oropharynx. What is New: • This is the first report on additional nasal breast milk application in very low birth weight preterm infants with severe brain injury observing a trend for less severe porencephalic defects. • The hypothesis is generated that nasal breast milk might exert neuroprotective effects in preterm infants.

Neurocognitive Outcome After Treatment With(out) ECMO for Neonatal Critical Respiratory or Cardiac Failure

Over the years, it has become clear that children growing up after neonatal critical illness are at high risk of long-term neurocognitive deficits that impact their school performance and daily life activities. Although the pathophysiological mechanisms remain largely unknown, emerging evidence seems to suggest that long-term neuropsychological deficits following neonatal critical illness are not associated with the type of treatment, such as extracorporeal membrane oxygenation (ECMO), but rather with underlying disease processes. In this review, neurocognitive outcome and brain pathology following neonatal critical respiratory and cardiac illness, either treated with or without ECMO, are described and compared in order to gain insight into potential underlying pathophysiological mechanisms. Putting these findings together, it becomes apparent that both children with complex congenital heart disease and children who survived severe respiratory failure are at risk of neurocognitive deficits later in life. Neurorehabilitation strategies, such as Cogmed working-memory training, are discussed. While prevention of neurocognitive deficits altogether should be strived for in the future, this is not realistic at this moment. It is therefore of great importance that children growing up after neonatal critical illness receive long-term care that includes psychoeducation and personalized practical tools that can be used to improve their daily life activities.

Robust increases in erythropoietin production by the hypoxic fetus is a response to protect the brain and other vital organs

Fetal erythropoietin (EPO), in addition to regulating erythropoiesis, has also tissue-protective properties based on its anti-inflammatory, anti-apoptotic, antioxidant, and neurotrophic effects. Notably, EPO concentrations needed for tissue protection are 100-1000 times higher than concentrations needed for regulating erythropoiesis. This dual effect of EPO is based on EPO-receptor (EPO-R) isoforms, which differ structurally and functionally. We hypothesize in this Integrated Mechanism Review that during severe fetal hypoxia the observed, but poorly understood, marked increases of fetal plasma EPO concentrations occur to protect the brain, heart, and other vital fetal organs. We further hypothesize that the concurrent marked increases of EPO in the amniotic fluid during fetal hypoxia, occur to protect newborn infants from necrotizing enterocolitis. This review presents experimental and clinical evidence in support of these hypotheses and points out unknown or poorly understood functions of EPO in the fetus. If these novel hypotheses are correct, the importance of fetal EPO as an antenatal hypoxia biomarker will become apparent. It will also likely point the way to important diagnostic and therapeutic fetal and neonatal interventions.

Behavioral and Socioemotional Development in Preterm Children

Prematurity is a significant risk factor for impaired neurodevelopmental outcomes. These include motor, cognitive, language, behavioral, and socioemotional competence. Long-term overall function depends on healthy socioemotional functioning. The vulnerability of the preterm brain during critical periods of development contributes to behavioral and socioemotional problems in preterm children. Attention deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) clinical features are more frequent in preterm children compared with their full-term counterparts; however, true rates of ASD and ADHD vary across studies. Early detection of behavioral and socioemotional problems in preterm children would enable timely early intervention to improve long-term functional outcomes.

Neuroprotective Effects of Mitochondria-Targeted Plastoquinone in a Rat Model of Neonatal Hypoxic⁻Ischemic Brain Injury

Neonatal hypoxia⁻ischemia is one of the main causes of mortality and disability of newborns. To study the mechanisms of neonatal brain cell damage, we used a model of neonatal hypoxia⁻ischemia in seven-day-old rats, by annealing of the common carotid artery with subsequent hypoxia of 8% oxygen. We demonstrate that neonatal hypoxia⁻ischemia causes mitochondrial dysfunction associated with high production of reactive oxygen species, which leads to oxidative stress. Targeted delivery of antioxidants to the mitochondria can be an effective therapeutic approach to treat the deleterious effects of brain hypoxia⁻ischemia. We explored the neuroprotective properties of the mitochondria-targeted antioxidant SkQR1, which is the conjugate of a plant plastoquinone and a penetrating cation, rhodamine 19. Being introduced before or immediately after hypoxia⁻ischemia, SkQR1 affords neuroprotection as judged by the diminished brain damage and recovery of long-term neurological functions. Using vital sections of the brain, SkQR1 has been shown to reduce the development of oxidative stress. Thus, the mitochondrial-targeted antioxidant derived from plant plastoquinone can effectively protect the brain of newborns both in pre-ischemic and post-stroke conditions, making it a promising candidate for further clinical studies.

How long is sufficient for optimal neuroprotection with cerebral cooling after ischemia in fetal sheep?

The optimal duration of mild "therapeutic" hypothermia for neonates with hypoxic-ischemic encephalopathy is surprisingly unclear. This study assessed the relative efficacy of cooling for 48 h versus 72 h. Fetal sheep (0.85 gestation) received sham ischemia (n = 9) or 30 min global cerebral ischemia followed by normothermia (n = 8) or delayed hypothermia from 3 h to 48 h (n = 8) or 72 h (n = 8). Ischemia was associated with profound loss of electroencephalogram (EEG) power, neurons in the cortex and hippocampus, and oligodendrocytes and myelin basic protein expression in the white matter, with increased Iba-1-positive microglia and proliferation. Hypothermia for 48 h was associated with improved outcomes compared to normothermia, but a progressive deterioration of EEG power after rewarming compared to 72 h of hypothermia, with impaired neuronal survival and myelin basic protein, and more microglia in the white matter and cortex. These findings show that head cooling for 48 h is partially neuroprotective, but is inferior to cooling for 72 h after cerebral ischemia in fetal sheep. The close association between rewarming at 48 h, subsequent deterioration in EEG power and increased cortical inflammation strongly suggests that deleterious inflammation can be reactivated by premature rewarming.

A working model for hypothermic neuroprotection

Therapeutic hypothermia significantly improves survival without disability in near-term and full-term newborns with moderate to severe hypoxic-ischaemic encephalopathy. However, hypothermic neuroprotection is incomplete. The challenge now is to find ways to further improve outcomes. One major limitation to progress is that the specific mechanisms of hypothermia are only partly understood. Evidence supports the concept that therapeutic cooling suppresses multiple extracellular death signals, including intracellular pathways of apoptotic and necrotic cell death and inappropriate microglial activation. Thus, the optimal depth of induced hypothermia is that which effectively suppresses the cell death pathways after hypoxia-ischaemia, but without inhibiting recovery of the cellular environment. Thus mild hypothermia needs to be continued until the cell environment has recovered until it can actively support cell survival. This review highlights that key survival cues likely include the inter-related restoration of neuronal activity and growth factor release. This working model suggests that interventions that target overlapping mechanisms, such as anticonvulsants, are unlikely to materially augment hypothermic neuroprotection. We suggest that further improvements are most likely to be achieved with late interventions that maximise restoration of the normal cell environment after therapeutic hypothermia, such as recombinant human erythropoietin or stem cell therapy.

[Effect of early application of recombinant human erythropoietin on white matter development in preterm infants]

OBJECTIVE

To evaluate the effect of early application of recombinant human erythropoietin (rhEPO) on white matter development in preterm infants using fractional anisotropy (FA) of magnetic resonance diffusion tensor imaging (DTI).

METHODS

A total of 81 preterm infants with gestational age &le;32 weeks, birth weight <1 500 g, and hospitalization within 24 hours after birth were randomly divided into rhEPO group (42 infants) and control group (39 infants). The infants in the rhEPO group were administered rhEPO, while those in the control group were given the same volume of normal saline. The preterm infants of both groups took examinations of head magnetic resonance imaging, diffusion-weighted imaging, and DTI at the corrected gestational age of 35-37 weeks. FA was calculated for the regions of interest in both groups.

RESULTS

There was no significant difference in the incidence of intracranial hemorrhage, periventricular leukomalacia, focal cerebral white matter damage (CWMD), and extensive CWMD between rhEPO and control groups (P&gt;0.05). Compared with the control group, the rhEPO group showed higher FA values at the posterior limb of the internal capsule, the splenium of the corpus callosum, frontal white matter, and occipital white matter (P&lt;0.05). There was no significant difference in FA values at the parietal white matter, thalamus, lenticular nucleus, and caudate nucleus between the two groups (P&gt;0.05).

CONCLUSIONS

Early application of rhEPO has a neuroprotective effect on white matter development in preterm infants.

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.

[Effect of early application of recombinant human erythropoietin on white matter development in preterm infants]

OBJECTIVE

To evaluate the effect of early application of recombinant human erythropoietin (rhEPO) on white matter development in preterm infants using fractional anisotropy (FA) of magnetic resonance diffusion tensor imaging (DTI).

METHODS

A total of 81 preterm infants with gestational age ≤32 weeks, birth weight <1 500 g, and hospitalization within 24 hours after birth were randomly divided into rhEPO group (42 infants) and control group (39 infants). The infants in the rhEPO group were administered rhEPO, while those in the control group were given the same volume of normal saline. The preterm infants of both groups took examinations of head magnetic resonance imaging, diffusion-weighted imaging, and DTI at the corrected gestational age of 35-37 weeks. FA was calculated for the regions of interest in both groups.

RESULTS

There was no significant difference in the incidence of intracranial hemorrhage, periventricular leukomalacia, focal cerebral white matter damage (CWMD), and extensive CWMD between rhEPO and control groups (P>0.05). Compared with the control group, the rhEPO group showed higher FA values at the posterior limb of the internal capsule, the splenium of the corpus callosum, frontal white matter, and occipital white matter (P<0.05). There was no significant difference in FA values at the parietal white matter, thalamus, lenticular nucleus, and caudate nucleus between the two groups (P>0.05).

CONCLUSIONS

Early application of rhEPO has a neuroprotective effect on white matter development in preterm infants.

Clinical Outcomes Related to the Gastrointestinal Trophic Effects of Erythropoietin in Preterm Neonates: A Systematic Review and Meta-Analysis

Erythropoietin (EPO) plays an important role in the development and maturation of the gastrointestinal tract. Recombinant EPO (rEPO) has been used to prevent anemia of prematurity. The gastrointestinal trophic effects of EPO may reduce feeding intolerance and necrotizing enterocolitis (NEC) in preterm neonates. The aim of this systematic review of randomized controlled trials (RCTs) was to evaluate the effects of rEPO on clinical outcomes such as feeding intolerance, stage II or higher NEC, any stage NEC, sepsis, retinopathy of prematurity, and bronchopulmonary dysplasia in preterm neonates. Twenty-five RCTs (intravenous: 13; subcutaneous: 10; enteral: 2; n = 4025) were eligible for inclusion. Meta-analysis of data from 17 RCTs (rEPO compared with placebo) with the use of a fixed-effects model showed no significant effect of rEPO on stage II or higher NEC (RR: 0.87; 95% CI: 0.64, 1.19; P = 0.39). Meta-analysis of data from 25 RCTs (rEPO compared with placebo) showed that rEPO significantly decreased the risk of any stage NEC [cases/total sample: 120/2058 (5.83%) compared with 146/1967 (7.42%); RR: 0.77; 95% CI: 0.61, 0.97; P = 0.03]. Only one RCT reported on time to full feedings. Meta-analysis of data from 15 RCTs showed a significant reduction in late-onset sepsis after rEPO administration (RR: 0.81; 95% CI: 0.71, 0.94; P = 0.004). Meta-analysis of 13 RCTs showed no significant effect of rEPO on mortality, retinopathy of prematurity, and bronchopulmonary dysplasia. Prophylactic rEPO had no effect on stage II or higher NEC, but it reduced any stage NEC, probably by reducing feeding intolerance, which is often labeled as stage I NEC. Adequately powered RCTs are required to confirm these findings.

Circulating biomarkers in extremely preterm infants associated with ultrasound indicators of brain damage

AIM

To assess to what extent the blood concentrations of proteins with neurotrophic and angiogenic properties measured during the first postnatal month convey information about the risk of sonographically-identified brain damage among very preterm newborns.

METHODS

Study participants were 1219 children who had a cranial ultrasound scan during their stay in the intensive care nursery and blood specimens collected on 2 separate days at least a week apart during the first postnatal month. Concentrations of selected proteins in blood spots were measured with electrochemiluminescence or with a multiplex immunobead assay and the risks of cranial ultrasound images associated with top-quartile concentrations were assessed.

RESULTS

High concentrations of multiple inflammation-related proteins during the first 2 postnatal weeks were associated with increased risk of ventriculomegaly, while high concentrations of just 3 inflammation-related proteins were associated with increased risk of an echolucent/hypoechoic lesion (IL-6, IL-8, ICAM-1), especially on day 7. Concomitant high concentrations of IL6R and bFGF appeared to modulate the increased risks of ventriculomegaly and an echolucent lesion associated with inflammation. More commonly high concentrations of putative protectors/repair-enhancers did not appear to diminish these increased risks.

CONCLUSION

Our findings provide support for the hypothesis that endogenous proteins are capable of either protecting the brain against damage and/or enhancing repair of damage.

The localization of α-synuclein in the process of differentiation of human erythroid cells

Although the neuronal protein α-synuclein (α-syn) is thought to play a central role in the pathogenesis of Parkinson's disease (PD), its physiological function remains unknown. It is known that α-syn is also abundantly expressed in erythrocytes. However, its role in erythrocytes is also unknown. In the present study, we investigated the localization of α-syn in human erythroblasts and erythrocytes. Protein expression of α-syn increased during terminal differentiation of erythroblasts (from day 7 to day 13), whereas its mRNA level peaked at day 11. α-syn was detected in the nucleus, and was also seen in the cytoplasm and at the plasma membrane after day 11. In erythroblasts undergoing nucleus extrusion (day 13), α-syn was detected at the periphery of the nucleus. Interestingly, we found that recombinant α-syn binds to trypsinized inside-out vesicles of erythrocytes and phosphatidylserine (PS) liposomes. The dissociation constants for binding to PS/phosphatidylcholine (PC) liposomes of N-terminally acetylated (NAc) α-syn was lower than that of non NAc α-syn. This suggests that N-terminal acetylation plays a significant functional role. The results of the present study collectively suggest that α-syn is involved in the enucleation of erythroblasts and the stabilization of erythroid membranes.

Melatonin protects against blood-brain barrier damage by inhibiting the TLR4/ NF-κB signaling pathway after LPS treatment in neonatal rats

Hypoxic-ischemic and inflammatory (HII) induces the disruption of blood–brain barrier (BBB) which leads to inflammatory responses and neuronal cell death, resulting in brain secondary damage. Previous studies showed that melatonin produced potent neuroprotective effects in neonatal hypoxic-ischaemic models. However, the relationship between BBB disruption and melatonin in HII was still unclear. The present study therefore investigated the beneficial effects of melatonin on BBB after HII and the underlying mechanisms. HII animal model was conducted by receiving lipopolysaccharide followed by 90 min hypoxia-ischaemia in postnatal day 2 Sprague–Dawley rat pups. Melatonin was injected intraperitoneally 1 h before lipopolysaccharide injection and then once a day for 1 week to evaluate the long-term effects. In this study, we demonstrated that melatonin administration inhibited the disruption of BBB permeability and improved the white matter recovery in HII model rats. Melatonin significantly attenuated the degradation of junction proteins and the neuroprotective role was related to the inhibition of microglial toll-like receptor 4/ nuclear factor-kappa B signaling pathway both in vivo and in vitro. Taken together, our data demonstrated that therapeutic strategies targeting inflammation might be suitable for the therapy of preserving BBB integrity after HII.

Evolving changes in fetal heart rate variability and brain injury after hypoxia-ischaemia in preterm fetal sheep

KEY POINTS

Fetal heart rate variability is a critical index of fetal wellbeing. Suppression of heart rate variability may provide prognostic information on the risk of hypoxic-ischaemic brain injury after birth. In the present study, we report the evolution of fetal heart rate variability after both mild and severe hypoxia-ischaemia. Both mild and severe hypoxia-ischaemia were associated with an initial, brief suppression of multiple measures of heart rate variability. This was followed by normal or increased levels of heart rate variability during the latent phase of injury. Severe hypoxia-ischaemia was subsequently associated with the prolonged suppression of measures of heart rate variability during the secondary phase of injury, which is the period of time when brain injury is no longer treatable. These findings suggest that a biphasic pattern of heart rate variability may be an early marker of brain injury when treatment or intervention is probably most effective.

ABSTRACT

Hypoxia-ischaemia (HI) is a major contributor to preterm brain injury, although there are currently no reliable biomarkers for identifying infants who are at risk. We tested the hypothesis that fetal heart rate (FHR) and FHR variability (FHRV) would identify evolving brain injury after HI. Fetal sheep at 0.7 of gestation were subjected to either 15 (n = 10) or 25 min (n = 17) of complete umbilical cord occlusion or sham occlusion (n = 12). FHR and four measures of FHRV [short-term variation, long-term variation, standard deviation of normal to normal R-R intervals (SDNN), root mean square of successive differences) were assessed until 72 h after HI. All measures of FHRV were suppressed for the first 3-4 h in the 15 min group and 1-2 h in the 25 min group. Measures of FHRV recovered to control levels by 4 h in the 15 min group, whereas the 25 min group showed tachycardia and an increase in short-term variation and SDNN from 4 to 6 h after occlusion. The measures of FHRV then progressively declined in the 25 min group and became profoundly suppressed from 18 to 48 h. A partial recovery of FHRV measures towards control levels was observed in the 25 min group from 49 to 72 h. These findings illustrate the complex regulation of FHRV after both mild and severe HI and suggest that the longitudinal analysis of FHR and FHRV after HI may be able to help determine the timing and severity of preterm HI.

Promoting neuroregeneration after perinatal arterial ischemic stroke: neurotrophic factors and mesenchymal stem cells

Newborns suffering from perinatal arterial ischemic stroke (PAIS) are at risk of neurodevelopmental problems. Current treatment options for PAIS are limited and mainly focus on supportive care, as presentation of PAIS is beyond the time window of current treatment strategies. Therefore, recent focus has shifted to interventions that stimulate regeneration of damaged brain tissue. From animal models, it is known that the brain increases its neurogenic capability after ischemic injury, by promoting neural cell proliferation and differentiation. However, neurogenesis is not maintained at the long term, which consequently impedes full repair leading to adverse consequences later in life. Boosting neuroregeneration of the newborn brain using treatment with neurotrophic factors and/or mesenchymal stem cells (MSCs) may be promising novel therapeutic strategies to improve neurological prospects and quality of life of infants with PAIS. This review focuses on effectiveness of neurotrophic growth factors, including erythropoietin, brain-derived neurotrophic factor, vascular endothelial growth factor, glial-derived neurotrophic factor, and MSC therapy, in both experimental neonatal stroke studies and first clinical trials for neonatal ischemic brain injury.

High-Dose Erythropoietin for Asphyxia and Encephalopathy (HEAL): A Randomized Controlled Trial - Background, Aims, and Study Protocol

BACKGROUND

Hypoxic-ischemic encephalopathy (HIE) remains an important cause of neonatal death and frequently leads to significant long-term disability in survivors. Therapeutic hypothermia, while beneficial, still leaves many treated infants with lifelong disabilities. Adjunctive therapies are needed, and erythropoietin (Epo) has the potential to provide additional neuroprotection.

OBJECTIVES

The aim of this study was to review the current incidence, mechanism of injury, and sequelae of HIE, and to describe a new phase III randomized, placebo-controlled trial of Epo neuroprotection in term and near-term infants with moderate to severe HIE treated with therapeutic hypothermia.

METHODS

This article presents an overview of HIE, neuroprotective functions of Epo, and the design of a double-blind, placebo-controlled, multicenter trial of high-dose Epo administration, enrolling 500 neonates ≥36 weeks of gestation with moderate or severe HIE diagnosed by clinical criteria.

RESULTS AND CONCLUSIONS

Epo has robust neuroprotective effects in preclinical studies, and phase I/II trials suggest that multiple high doses of Epo may provide neuroprotection against brain injury in term infants. The High Dose Erythropoietin for Asphyxia and Encephalopathy (HEAL) Trial will evaluate whether high-dose Epo reduces the combined outcome of death or neurodevelopmental disability when given in conjunction with hypothermia to newborns with moderate/severe HIE.

Erythropoietin Signaling Regulates Key Epigenetic and Transcription Networks in Fetal Neural Progenitor Cells

Erythropoietin (EPO) and its receptor are highly expressed in the developing nervous system, and exogenous EPO therapy is potentially neuroprotective, however the epigenetic and transcriptional changes downstream of EPO signaling in neural cells are not well understood. To delineate epigenetic changes associated with EPO signaling, we compared histone H3 lysine 4 dimethylation (H3K4me2) in EPO treated and control fetal neural progenitor cells, identifying 1,150 differentially bound regions. These regions were highly enriched near protein coding genes and had significant overlap with H4Acetylation, a mark of active regulatory elements. Motif analyses and co-occupancy studies revealed a complex regulatory network underlying the differentially bound regions, including previously identified mediators of EPO signaling (STAT5, STAT3), and novel factors such as REST, an epigenetic modifier central to neural differentiation and plasticity, and NRF1, a key regulator of antioxidant response and mitochondrial biogenesis. Global transcriptome analyses on neural tubes isolated from E9.0 EpoR-null and littermate control embryos validated our in vitro findings, further suggesting a role for REST and NRF1 downstream of EPO signaling. These data support a role for EPO in regulating the survival, proliferation, and differentiation of neural progenitor cells, and suggest a basis for its function in neural development and neuroprotection.

Embracing oligodendrocyte diversity in the context of perinatal injury

Emerging evidence is fueling a new appreciation of oligodendrocyte diversity that is overturning the traditional view that oligodendrocytes are a homogenous cell population. Oligodendrocytes of distinct origins, maturational stages, and regional locations may differ in their functional capacity or susceptibility to injury. One of the most unique qualities of the oligodendrocyte is its ability to produce myelin. Myelin abnormalities have been ascribed to a remarkable array of perinatal brain injuries, with concomitant oligodendrocyte dysregulation. Within this review, we discuss new insights into the diversity of the oligodendrocyte lineage and highlight their relevance in paradigms of perinatal brain injury. Future therapeutic development will be informed by comprehensive knowledge of oligodendrocyte pathophysiology that considers the particular facets of heterogeneity that this lineage exhibits.

Treatment options for severe traumatic brain injuries in children: current therapies, challenges, and future prospects

INTRODUCTION

Severe traumatic brain injury (TBI) afflicts many children and adults worldwide, resulting in high rates of morbidity and mortality. Recent therapeutic advances have focused on both surgical and medical treatment options, but none have been proven to reduce overall morbidity and mortality in this population. Areas covered: Several emerging therapies are addressed that focus on treating related secondary injuries and other clinical sequelae post-TBI during the acute injury phase (defined by authors as up to four weeks post-injury). Information and data were obtained from a PubMed search of recent literature and through reputable websites (e.g. Centers for Disease Control, ClinicalTrials.gov). Peer-reviewed original articles, review articles, and clinical guidelines were included. Expert commentary: The ongoing challenges related to conducting rigorous clinical trials in TBI have led to largely inconclusive findings regarding emerging beneficial therapies.

Erythropoietin Promotes Glioblastoma via miR-451 Suppression

Erythropoietin (EPO) is an erythropoiesis stimulating growth factor and hormone. EPO has been widely used in the treatment of chronic renal failure, cancer, and chemotherapy-related anemia for three decades. However, many clinical trials showed that EPO treatment may be associated with tumorigenesis and cancer progression. EPO is able to cross blood-brain barriers, and this may lead to an increased possibility of central nervous system tumors such as glioblastoma. Indeed, EPO promotes glioblastoma growth and invasion in animal studies. Additionally, EPO increases glioblastoma cell survival, proliferation, migration, invasion, and chemoresistancy in vitro. However, the exact mechanisms of cancer progression induced by EPO treatment are not fully understood. Posttranscriptional gene regulation through microRNAs may contribute to EPO's cellular and biological effects in tumor progression. Here, we aimed to study whether tumor suppressive microRNA, miR-451, counteracts the positive effects of EPO on U87 human glioblastoma cell line. Migration and invasion were evaluated by scratch assay and transwell invasion assay, respectively. We found that EPO decreased basal miR-451 expression and increased cell proliferation, migration, invasion, and cisplatin chemoresistancy in vitro. miR-451 overexpression by transfection of its mimic significantly reversed these effects. Furthermore, ectopic expression of miR-451 inhibited expression of its own target genes, such as metalloproteinases-2 and -9, which are stimulated by EPO treatment and involved in carcinogenesis processes, especially invasion. These findings suggest that miR-451 mimic delivery may be useful as adjuvant therapy in addition to chemotherapy and anemia treatment by EPO and should be tested in experimental glioblastoma models.

The Anti-Aging Effect of Erythropoietin via the ERK/Nrf2-ARE Pathway in Aging Rats

Erythropoietin (EPO) has a neuroprotective effect and can resist aging, which most likely occur through EPO increasing the activity of antioxidant enzymes and scavenging free radicals. In this study, we verified the anti-aging function of EPO and discussed the mechanism occurring through the extracellular signal-regulated kinase (ERK)/NF-E2-related factor 2 (Nrf2)-ARE pathway. A rat model of aging was induced by the continuous subcutaneous injection of 5 % D-galactose for 6 weeks. At the beginning of the sixth week, physiological saline or EPO was administered twice per day through a lateral ventricle system for a total of 7 days. In one group, 2 μl PD98059 was administered 30 min before EPO. Learning and memory ability were analyzed with the Morris water maze system. HE staining was used to observe the morphological changes in the neurons in the hippocampus, and immunohistochemical staining as well as Western blots were carried out to detect the expression of ERK for each group of rats and the expression of phosphorylated-ERK (P-ERK), Nrf2, and superoxide dismutase (SOD). Real-Time PCR was carried out to detect the amount of Nrf2 mRNA and the KEAP1 mRNA expression. EPO can significantly improve learning and memory ability in aging rats and can provide protection against aging by improving the hippocampus morphology. Immunohistochemical staining and Western blots showed P-ERK, Nrf2, and Cu-Zn SOD decreases in aging rats compared to the normal group, while the expression for those proteins increased after EPO intervention. PD98059 inhibited the enhanced expression of P-ERK, Nrf2, and Cu-Zn SOD induced by EPO. Real-Time PCR results suggested that the trend of Nrf2mRNA expression was the same as that for the proteins, which confirmed that the enhancement occurred at the gene level. As such, EPO can significantly resist or delay aging and protect the brain by reducing oxidative stress. The most likely mechanism is that EPO can promote the ERK/Nrf2-ARE pathway in aging rats and that PD98059 can inhibit that process. These findings may facilitate further studies on the mechanism of aging and applications for the neuroprotective properties of EPO for clinical treatments.

Neuroprotective Effect of Erythropoietin on Phenylhydrazine-Induced Hemolytic Hyperbilirubinemia in Neonatal Rats

Neonatal unconjugated hyperbilirubinemia might cause severe bilirubin neurotoxicity in especially hemolytic conditions. The study aimed to elucidate the potential neuroprotective effects of erythropoietin (EPO) in hemolysis-induced hyperbilirubinemia. In newborn rats, hyperbilirubinemia secondary to hemolysis was induced by injecting with phenylhydrazine hydrochloride (PHZ) and rats were injected with either vehicle or EPO. At 54th hour of the PHZ injection, rats were decapitated. Serum levels of TNF-α, IL-1β, IL-10, brain-derived neurotrophic factor (BDNF) and S100-B and brain malondialdehyde, glutathione levels and myeloperoxidase activities were measured. TUNEL staining and NF-κB expression were evaluated. As compared to control pups, in vehicle-treated PHZ group, TNF-α and IL-1β levels, malondialdehyde level and myeloperoxidase activity were increased with concomitant decreases in IL-10 and glutathione. All EPO regimens reversed PHZ-induced alterations in IL-10, TNF-α, malondialdehyde and glutathione levels. Three-day-treatment abolished increases in myeloperoxidase activity and IL-1β levels, while BDNF and S100-B were elevated. Increased TUNEL (+) cells and NF-κB expressions in the brain of PHZ group were reduced in the 3-day-treated group. EPO exerted anti-inflammatory effects on PHZ-induced neural damage in newborn rats, while the neuroprotection was more obvious when the treatments were repeated successively. The results suggest that EPO treatment may have a therapeutic potential in supporting neuroplasticity in the hyperbilirubinemic neonates.

Neonatal Encephalopathy: Update on Therapeutic Hypothermia and Other Novel Therapeutics

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

Erythropoietin Restores Long-Term Neurocognitive Function Involving Mechanisms of Neuronal Plasticity in a Model of Hyperoxia-Induced Preterm Brain Injury

Cerebral white and grey matter injury is the leading cause of an adverse neurodevelopmental outcome in prematurely born infants. High oxygen concentrations have been shown to contribute to the pathogenesis of neonatal brain damage. Here, we focused on motor-cognitive outcome up to the adolescent and adult age in an experimental model of preterm brain injury. In search of the putative mechanisms of action we evaluated oligodendrocyte degeneration, myelination, and modulation of synaptic plasticity-related molecules. A single dose of erythropoietin (20,000 IU/kg) at the onset of hyperoxia (24 hours, 80% oxygen) in 6-day-old Wistar rats improved long-lasting neurocognitive development up to the adolescent and adult stage. Analysis of white matter structures revealed a reduction of acute oligodendrocyte degeneration. However, erythropoietin did not influence hypomyelination occurring a few days after injury or long-term microstructural white matter abnormalities detected in adult animals. Erythropoietin administration reverted hyperoxia-induced reduction of neuronal plasticity-related mRNA expression up to four months after injury. Thus, our findings highlight the importance of erythropoietin as a neuroregenerative treatment option in neonatal brain injury, leading to improved memory function in adolescent and adult rats which may be linked to increased neuronal network connectivity.

Treatment temperature and insult severity influence the neuroprotective effects of therapeutic hypothermia

Therapeutic hypothermia (HT) is standard care for moderate and severe neonatal hypoxic-ischaemic encephalopathy (HIE), the leading cause of permanent brain injury in term newborns. However, the optimal temperature for HT is still unknown, and few preclinical studies have compared multiple HT treatment temperatures. Additionally, HT may not benefit infants with severe encephalopathy. In a neonatal rat model of unilateral hypoxia-ischaemia (HI), the effect of five different HT temperatures was investigated after either moderate or severe injury. At postnatal-day seven, rat pups underwent moderate or severe HI followed by 5 h at normothermia (37 °C), or one of five HT temperatures: 33.5 °C, 32 °C, 30 °C, 26 °C, and 18 °C. One week after treatment, neuropathological analysis of hemispheric and hippocampal area loss, and CA1 hippocampal pyramidal neuron count, was performed. After moderate injury, a significant reduction in hemispheric and hippocampal loss on the injured side, and preservation of CA1 pyramidal neurons, was seen in the 33.5 °C, 32 °C, and 30 °C groups. Cooling below 33.5 °C did not provide additional neuroprotection. Regardless of treatment temperature, HT was not neuroprotective in the severe HI model. Based on these findings, and previous experience translating preclinical studies into clinical application, we propose that milder cooling should be considered for future clinical trials.

Nonsurgical therapy for hydrocephalus: a comprehensive and critical review

Pharmacological interventions have been tested experimentally and clinically to prevent hydrocephalus and avoid the need for shunting beginning in the 1950s. Clinical trials of varied quality have not demonstrated lasting and convincing protective effects through manipulation of cerebrospinal fluid production, diuresis, blood clot fibrinolysis, or manipulation of fibrosis in the subarachnoid compartment, although there remains some promise in the latter areas. Acetazolamide bolus seems to be useful for predicting shunt response in adults with hydrocephalus. Neuroprotection in the situation of established hydrocephalus has been tested experimentally beginning more recently. Therapies designed to modify blood flow or pulsation, reduce inflammation, reduce oxidative damage, or protect neurons are so far of limited success; more experimental work is needed in these areas. As has been recommended for preclinical studies in stroke and brain trauma, stringent conditions should be met for preclinical studies in hydrocephalus.

Anticytokine Autoantibodies: Association with Infection and Immune Dysregulation

The association of autoantibodies to cytokines with immune deficiency, autoimmunity and/or immune dysregulation is increasingly being recognized. For example, autoantibodies to interferon gamma have been found to be associated with chronic, treatment refractory infections with intracellular organisms such as mycobacteria, autoantibodies to interleukin 17 with chronic mucocutaneous candidiasis, and anti-interferon alpha autoantibodies with systemic lupus erythematosus. While low titer autoantibodies to these and other cytokines may be detected in normal individuals, patients with infectious or autoimmune manifestations tend to have high titer autoantibodies that may block or potentiate the function of the respective cytokine. Recognition of these autoantibodies is important because it may direct treatment toward a combination of adjunctive immunotherapy to modulate the autoantibody level while continuing with appropriate anti-microbial therapy. This review focuses on the anti-cytokine autoantibodies documented to date, their autoimmune, immune dysregulation and infectious disease associations, methods for detection of these antibodies and potential treatment options.