Erythropoietin as a Neuroprotective Drug for Newborn Infants: Ten Years after the First Use

Enduring effects of acute prenatal ischemia in rat soleus muscle, and protective role of erythropoietin

Motor disorders are considered to originate mainly from brain lesions. Placental dysfunction or maternal exposure to a persistently hypoxic environment is a major cause of further motor disorders such as cerebral palsy. Our main goal was to determine the long-term effects of mild intrauterine acute ischemic stress on rat soleus myofibres and whether erythropoietin treatment could prevent these changes. Rat embryos were subjected to ischemic stress at embryonic day E17. They then received an intraperitoneal erythropoietin injection at postnatal days 1-5. Soleus muscles were collected at postnatal day 28. Prenatal ischemic stress durably affected muscle structure, as indicated by the greater fiber cross-sectional area (+ 18%) and the greater number of mature vessels (i.e. vessels with mature endothelial cells) per myofibres (+ 43%), and muscle biochemistry, as shown by changes in signaling pathways involved in protein synthesis/degradation balance (-81% for 4EBP1; -58% for AKT) and Hif1α expression levels (+ 95%). Erythropoietin injection in ischemic pups had a weak protective effect: it increased muscle mass (+ 25% with respect to ischemic pups) and partially prevented the increase in muscle degradation pathways and mature vascularization, whereas it exacerbated the decrease in synthesis pathways. Hence, erythropoietin treatment after acute ischemic stress contributes to muscle adaptation to ischemic conditions.

Current status and controversies in the treatment of neonatal hypoxic-ischemic encephalopathy: A review

Neonatal hypoxic-ischemic encephalopathy is a type of traumatic brain injury caused by insufficient cerebral perfusion and oxygen supply in the perinatal neonate, which can be accompanied by different types of long-term neurodevelopmental sequelae, such as cerebral palsy, learning disabilities, mental retardation and epilepsy It is one of the main causes of neonatal death and disability, and it has caused a great burden on families and society. Therefore, this article mainly reviews the latest developments in mild hypothermia therapy and related drugs for neonatal hypoxic-ischemic encephalopathy.

Shengmaisan combined with Liuwei Dihuang Decoction alleviates chronic intermittent hypoxia-induced cognitive impairment by activating the EPO/EPOR/JAK2 signaling pathway

Chronic intermittent hypoxia (CIH), a principal pathophysiological aspect of obstructive sleep apnea (OSA), is associated with cognitive deficits. Clinical evidence suggests that a combination of Shengmaisan and Liuwei Dihuang Decoctions (SMS-LD) can enhance cognitive function by nourishing yin and strengthening the kidneys. This study aimed to assess the efficacy and underlying mechanisms of SMS-LD in addressing cognitive impairments induced by CIH. We exposed C57BL/6N mice to CIH for five weeks (20%-5% O2, 5 min/cycle, 8 h/day) and administered SMS-LD intragastrically (15.0 or 30 g·kg-1·day) 30 min before each CIH session. Additionally, AG490, a JJanus kinase 2 (JAK2) inhibitor, was administered via intracerebroventricular injection. Cognitive function was evaluated using the Morris water maze, while synaptic and mitochondrial structures were examined by transmission electron microscopy. Oxidative stress levels were determined using DHE staining, and the activation of the erythropoietin (ER)/ER receptor (EPOR)/JAK2 signaling pathway was analyzed through immunohistochemistry and Western blotting. To further investigate molecular mechanisms, HT22 cells were treated in vitro with either SMS-LD medicated serum alone or in combination with AG490 and then exposed to CIH for 48 h. Our results indicate that SMS-LD significantly mitigated CIH-induced cognitive impairments in mice. Specifically, SMS-LD treatment enhanced dendritic spine density, ameliorated mitochondrial dysfunction, reduced oxidative stress, and activated the EPO/EPOR/JAK2 signaling pathway. Conversely, AG490 negated SMS-LD's neuroprotective and cognitive improvement effects under CIH conditions. These findings suggest that SMS-LD's beneficial impact on cognitive impairment and synaptic and mitochondrial integrity under CIH conditions may predominantly be attributed to the activation of the EPO/EPOR/JAK2 signaling pathway.

Early Postnatal Administration of Erythropoietin and Its Association with Neurodevelopmental Outcomes and Incidence of Intraventricular Hemorrhage and Hypoxic-Ischemic Encephalopathy: A Four-Week Observational Study

This study aimed to investigate the impact of early erythropoietin (EPO) administration on the neurodevelopment of newborns, specifically focusing on its effects on hypoxic-ischemic encephalopathy (HIE) and intraventricular hemorrhage (IVH). The primary objective was to determine whether early EPO administration could impact the short-term neurodevelopmental outcomes and provide safety in neonates at risk for neurodevelopmental disorders. Conducted at the "Louis Turcanu" Children's Emergency Clinical Hospital in Timisoara, Romania, this observational study included 121 neonates receiving EPO and 130 No EPO controls. EPO was administered within the first 48 h of life, with doses of 1000 U/kg that escalated to 2000 U/kg if necessary. Besides observing the occurrence of IVH and HIE, this study measured clinical and biochemical markers, including LDH, blood glucose, urea, creatinine, CPK, CRP, PCT, and erythropoietin levels alongside hematology and coagulation profiles. There were no significant differences in baseline characteristics between the groups. The EPO group showed significant reductions in LDH levels from days 1-3 to 7-10 (695.0 U/L to 442.0 U/L) and the APTT value (54.0 s) compared with the No EPO group (38.0 s). Notably, early EPO administration was associated with a significant decrease in HIE severity (beta coefficient: -0.38, p = 0.001). Additionally, lower gestational ages and hemoglobin levels correlated with increased severity of HIE. By week four, there was a significant reduction in moderate and severe HIE cases in the EPO group compared with controls (p = 0.001). Early administration of EPO in neonates significantly reduced the severity of IVH and HIE, suggesting its potential as a neuroprotective agent in neonatal care.

Neuroprotective efficacy of hypothermia and Inter-alpha Inhibitor Proteins after hypoxic ischemic brain injury in neonatal rats

Therapeutic hypothermia is the standard of care for hypoxic-ischemic (HI) encephalopathy. Inter-alpha Inhibitor Proteins (IAIPs) attenuate brain injury after HI in neonatal rats. Human (h) IAIPs (60 ​mg/kg) or placebo (PL) were given 15 ​min, 24 and 48 ​h to postnatal (P) day-7 rats after carotid ligation and 8% oxygen for 90 ​min with (30 ​°C) and without (36 ​°C) exposure to hypothermia 1.5 ​h after HI for 3 ​h. Hemispheric volume atrophy (P14) and neurobehavioral tests including righting reflex (P8-P10), small open field (P13-P14), and negative geotaxis (P14) were determined. Hemispheric volume atrophy in males was reduced (P ​< ​0.05) by 41.9% in the normothermic-IAIP and 28.1% in the hypothermic-IAIP compared with the normothermic-PL group, and in females reduced (P ​< ​0.05) by 30.3% in the normothermic-IAIP, 45.7% in hypothermic-PL, and 55.2% in hypothermic-IAIP compared with the normothermic-PL group after HI. Hypothermia improved (P ​< ​0.05) the neuroprotective effects of hIAIPs in females. The neuroprotective efficacy of hIAIPs was comparable to hypothermia in female rats (P ​= ​0.183). Treatment with hIAIPs, hypothermia, and hIAIPs with hypothermia decreased (P ​< ​0.05) the latency to enter the peripheral zone in the small open field test in males. We conclude that hIAIPs provide neuroprotection from HI brain injury that is comparable to the protection by hypothermia, hypothermia increases the effects of hIAIPs in females, and hIAIPs and hypothermia exhibit some sex-related differential effects.

Monitoring SpO2: The Basics of Retinopathy of Prematurity (Back to Basics) and Targeting Oxygen Saturation

Oxygen (O2) is a drug frequently used in newborn care. Adverse effects of hypoxia are well known but the damaging effects of excess oxygen administration and oxidative stress have only been studied in the last 2 decades. Many negative effects have been described, including retinopathy of prematurity . Noninvasive pulse oximetry (SpO2) is useful to detect hypoxemia but requires careful evaluation and understanding of the frequently changing relationship between O2 and hemoglobin to prevent hyperoxemia. Intention to treat SpO2 ranges should be individualized for every newborn receiving supplemental O2, according to gestational age, post-natal age, and clinical condition.

Evaluating the Safety and Efficacy of Erythropoietin Therapy for Neonatal Hypoxic-Ischemic Encephalopathy: A Systematic Review and Meta-Analysis

BACKGROUND

Erythropoietin (EPO) is a proposed drug for the treatment of neonatal hypoxic-ischemic encephalopathy (HIE). Multiple studies have linked its use, either as a monotherapy or in conjunction with therapeutic hypothermia (TH), with improved neonatal outcomes including death and neurodisability. However, there is also evidence in the literature that raises concerns about its efficacy and safety for the treatment of neonatal encephalopathy (NE).

METHODS

We searched MEDLINE, Cochrane CENTRAL, and Embase for both observational studies and randomized controlled trials (RCTs) investigating the effectiveness of EPO in treating NE. Only studies in which at least 300 U/kg of EPO was used and reported any one of the following outcomes: death, death or neurodisability, and cerebral palsy, were included.

RESULTS

Seven studies with 903 infants with the diagnosis of NE were included in our meta-analysis. EPO did not reduce the risk of death or neurodisability (risk ratio 0.68 [95% confidence interval [CI]: 0.43 to 1.09]) (P = 0.11). Similarly, the risk of cerebral palsy was not reduced by the administration of EPO (risk ratio 0.68 [95% CI: 0.33 to 1.40]) (P = 0.30). The risk of death was also not reduced at any dose of EPO regardless of the use of TH.

CONCLUSIONS

The results of our meta-analysis do not support the use of EPO for the treatment of neonatal encephalopathy. However, future large-scale RCTs are needed to strengthen these findings.

Angiogenic responses are enhanced by recombinant human erythropoietin in a model of periventricular white matter damage of neonatal rats through EPOR-ERK1 signaling

Recombinant human erythropoietin (rh-EPO) has been shown to stimulate neurogenesis and angiogenesis, both of which play crucial roles in the repair of brain injuries. Previously, we observed that rh-EPO treatment effectively reduced brain damage and enhanced angiogenesis in a neonatal rat model of periventricular white matter damage (PWMD). The objective of this research is to investigate the specific mechanism through which rh-EPO regulates angiogenesis following PWMD in premature neonates. We conducted experiments utilizing a neonatal PWMD model. Following rh-EPO treatment, the levels of erythropoietin receptor (EPOR) were found to be increased in the damaged brain of rats. Although the total amount of extracellular signal-regulated kinase (ERK), a downstream protein in the EPO signaling pathway, remained unchanged, there was clear upregulation of phosphorylated ERK1 (p-ERK1) levels. The increase in levels of p-ERK1 was inhibited by an ERK kinase inhibitor, while the total amount of ERK remained unchanged. Conversely, the levels of EPOR were not affected by the inhibitor. Notably, the introduction of rh-EPO led to a significant increase in the frequency of angiogenesis-related cells and the expression levels of angiogenic factors. However, these effects were nullified when the ERK pathway was blocked. These findings indicate that rh-EPO enhances angiogenic responses through the EPOR-ERK1 pathway in a neonatal PWMD model.

Brain Maturation as a Fundamental Factor in Immune-Neurovascular Interactions in Stroke

Injuries in the developing brain cause significant long-term neurological deficits. Emerging clinical and preclinical data have demonstrated that the pathophysiology of neonatal and childhood stroke share similar mechanisms that regulate brain damage, but also have distinct molecular signatures and cellular pathways. The focus of this review is on two different diseases-neonatal and childhood stroke-with emphasis on similarities and distinctions identified thus far in rodent models of these diseases. This includes the susceptibility of distinct cell types to brain injury with particular emphasis on the role of resident and peripheral immune populations in modulating stroke outcome. Furthermore, we discuss some of the most recent and relevant findings in relation to the immune-neurovascular crosstalk and how the influence of inflammatory mediators is dependent on specific brain maturation stages. Finally, we comment on the current state of treatments geared toward inducing neuroprotection and promoting brain repair after injury and highlight that future prophylactic and therapeutic strategies for stroke should be age-specific and consider gender differences in order to achieve optimal translational success.

Erythropoietin regulates developmental myelination in the brain stimulating postnatal oligodendrocyte maturation

Myelination is a process tightly regulated by a variety of neurotrophic factors. Here, we show-by analyzing two transgenic mouse lines, one overexpressing EPO selectively in the brain Tg21(PDGFB-rhEPO) and another with targeted removal of EPO receptors (EPORs) from oligodendrocyte progenitor cells (OPC)s (Sox10-cre;EpoRfx/fx mice)-a key function for EPO in regulating developmental brain myelination. Overexpression of EPO resulted in faster postnatal brain growth and myelination, an increased number of myelinating oligodendrocytes, faster axonal myelin ensheathment, and improved motor coordination. Conversely, targeted ablation of EPORs from OPCs reduced the number of mature oligodendrocytes and impaired motor coordination during the second postnatal week. Furthermore, we found that EPORs are transiently expressed in the subventricular zone (SVZ) during the second postnatal week and EPO increases the postnatal expression of essential oligodendrocyte pro-differentiation and pro-maturation (Nkx6.2 and Myrf) transcripts, and the Nfatc2/calcineurin pathway. In contrast, ablation of EPORs from OPCs inactivated the Erk1/2 pathway and reduced the postnatal expression of the transcripts. Our results reveal developmental time windows in which EPO therapies could be highly effective for stimulating oligodendrocyte maturation and myelination.

Brain-Oriented Strategies for Neuroprotection of Asphyxiated Newborns in the First Hours of Life

Perinatal asphyxia represents the first cause of severe neurological disabilities and the second cause of neonatal death in term-born babies. Currently, no treatment can prevent immediate cell death from necrosis, but some therapeutic interventions, such as therapeutic hypothermia (TH), can reduce delayed cell death from apoptosis. TH significantly improves the combined outcome of mortality or major neurodevelopmental disability, but the number of patients to be treated is 7 to get 1 child with no adverse neurological outcome. The aim of this educational review is to analyze the other care strategies to be implemented to improve the neurological outcome of children with hypoxic ischemic encephalopathy (HIE). Hypocapnia, hypoglycemia, pain control, and functional brain monitoring are recognized as appropriate approaches to improve outcome in critically ill infants with HIE. Pharmacologic neuroprotective adjuncts are currently under investigation. New drugs such as allopurinol and melatonin seem to provide positive effects although more randomized controlled trials are required to establish the effective therapeutic scheme. In the meantime, sustaining the respiratory, metabolic, and cardiovascular system during TH can be a valuable aid in managing and treating the patient with HIE in an optimal way.

Brain Damage in Preterm and Full-Term Neonates: Serum Biomarkers for the Early Diagnosis and Intervention

The Brain is vulnerable to numerous insults that can act in the pre-, peri-, and post-natal period. There is growing evidence that demonstrate how oxidative stress (OS) could represent the final common pathway of all these insults. Fetuses and newborns are particularly vulnerable to OS due to their inability to active the antioxidant defenses. Specific molecules involved in OS could be measured in biologic fluids as early biomarkers of neonatal brain injury with an essential role in neuroprotection. Although S-100B seems to be the most studied biomarker, its use in clinical practice is limited by the complexity of brain damage etiopathogenesis and the time of blood sampling in relation to the brain injury. Reliable early specific serum markers are currently lacking in clinical practice. It is essential to determine if there are specific biomarkers that can help caregivers to monitor the progression of the disease in order to active an early neuroprotective strategy. We aimed to describe, in an educational review, the actual evidence on serum biomarkers for the early identification of newborns at a high risk of neurological diseases. To move the biomarkers from the bench to the bedside, the assays must be not only be of a high sensitivity but suitable for the very rapid processing and return of the results for the clinical practice to act on. For the best prognosis, more studies should focus on the association of these biomarkers to the type and severity of perinatal brain damage.

N-Acetylcysteine Administration Attenuates Sensorimotor Impairments Following Neonatal Hypoxic-Ischemic Brain Injury in Rats

Hypoxic ischemic (HI) brain injury that occurs during neonatal period has been correlated with severe neuronal damage, behavioral deficits and infant mortality. Previous evidence indicates that N-acetylcysteine (NAC), a compound with antioxidant action, exerts a potential neuroprotective effect in various neurological disorders including injury induced by brain ischemia. The aim of the present study was to investigate the role of NAC as a potential therapeutic agent in a rat model of neonatal HI brain injury and explore its long-term behavioral effects. To this end, NAC (50 mg/kg/dose, i.p.) was administered prior to and instantly after HI, in order to evaluate hippocampal and cerebral cortex damage as well as long-term functional outcome. Immunohistochemistry was used to detect inducible nitric oxide synthase (iNOS) expression. The results revealed that NAC significantly alleviated sensorimotor deficits and this effect was maintained up to adulthood. These improvements in functional outcome were associated with a significant decrease in the severity of brain damage. Moreover, NAC decreased the short-term expression of iNOS, a finding implying that iNOS activity may be suppressed and that through this action NAC may exert its therapeutic action against neonatal HI brain injury.