Hypothermia Plus Melatonin in Asphyctic Newborns: A Randomized-Controlled Pilot Study

Neuroprotection for neonatal hypoxic-ischemic encephalopathy: A review of novel therapies evaluated in clinical studies

Therapeutic hypothermia is an effective therapy for moderate-to-severe hypoxic-ischemic encephalopathy (HIE) in infants born at term or near-term in high-resource settings. Yet there remains a substantial proportion of infants who do not benefit or who will have significant disability despite therapeutic hypothermia. Novel investigational therapies that may confer additional neuroprotection by targeting known pathogenic mechanisms of hypoxic-ischemic brain injury are under development. This review focuses on putative neuroprotective agents that have shown promise in animal models of HIE, and that have been translated to clinical studies in neonates with HIE. We include agents that have been studied both with and without concurrent therapeutic hypothermia. Our review therefore addresses not just neonatal HIE in high-resource countries where therapeutic hypothermia is the standard of care, but also neonatal HIE in low- and middle-income countries where therapeutic hypothermia has been shown to be ineffective, and where the greatest burden of HIE-related morbidity and mortality exists.

Mechanistic Insights into Melatonin's Antiarrhythmic Effects in Acute Ischemia-Reperfusion-Injured Rabbit Hearts Undergoing Therapeutic Hypothermia

The electrophysiological mechanisms underlying melatonin's actions and the electrophysiological consequences of superimposed therapeutic hypothermia (TH) in preventing cardiac ischemia-reperfusion (IR) injury-induced arrhythmias remain largely unknown. This study aimed to unveil these issues using acute IR-injured hearts. Rabbits were divided into heart failure (HF), HF+melatonin, control, and control+melatonin groups. HF was induced by rapid right ventricular pacing. Melatonin was administered orally (10 mg/kg/day) for four weeks, and IR was created by 60-min coronary artery ligation and 30-min reperfusion. The hearts were then excised and Langendorff-perfused for optical mapping studies at normothermia, followed by TH. Melatonin significantly reduced ventricular fibrillation (VF) maintenance. In failing hearts, melatonin reduced the spatially discordant alternans (SDA) inducibility mainly by modulating intracellular Ca2+ dynamics via upregulation of sarcoplasmic reticulum Ca2+-ATPase (SERCA2a) and calsequestrin 2 and attenuating the downregulation of phosphorylated phospholamban protein expression. In control hearts, melatonin improved conduction slowing and reduced dispersion of action potential duration (APDdispersion) by upregulating phosphorylated connexin 43, attenuating the downregulation of SERCA2a and phosphorylated phospholamban and attenuating the upregulation of phosphorylated Ca2+/calmodulin-dependent protein kinase II. TH significantly retarded intracellular Ca2+ decay slowed conduction, and increased APDdispersion, thereby facilitating SDA induction, which counteracted the beneficial effects of melatonin in reducing VF maintenance.

The association between melatonin-containing food consumption and sleep/meal timing and behavior in children with language difficulties

The purpose of this study was to investigate the sleep characteristics, circadian rhythms, behavior, and postnatal development of children with and without language difficulties (LDs) and the association of these variables with melatonin-containing food (FMT) consumption. The study involved parents who anonymously and voluntarily provided their children's personal data and assessed LDs, bedtime, meal timing, behavioral problems, gross motor skill development, and FMT consumption. Multiple regression analysis was used to analyze the associations between study variables. A total of 587 children were examined, with mean age M (SD) 5.5 (2.4) years, (range: 2-12 years), and 44.2% were boys. Children with LD had delayed sleep onset (β = 0.09; R2 = 0.007), increased sleep latency (β = 0.11; R2 = 0.014), social jetlag (β = 0.10; R2 = 0.009), screen time (β = 0.14; R2 = 0.022), and behavioral problems (β = 0.13-0.35; R2 = 0.016-0.142); decreased gestational age at birth (β = -0.09; R2 = 0.007), and delayed development of gross motor skills in the postpartum period (β = 0.11-0.21; R2 = 0.012-0.064). The children's average FMT consumption was 2087.6 ± 2401.3 ng/d. Children with the highest FMT consumption had lower rates of LDs (β = -0.11; R2 = 0.010), social jetlag (β = -0.08; R2 = 0.007), and eating jetlag (β = -0.12; R2 = 0.013); fever behavioral problems (β = -0.09 - -0.10; R2 = 0.007-0.057); and less delayed eating phase (β = -0.11; R2 = 0.012), and development of gross motor skills in the postpartum period (β = -0.10 - -0.12; R2 = 0.009-0.014). In summary, LDs in children were associated with higher rates of circadian misalignment, sleep, behavioral, and developmental dysfunctions, and higher FMT consumption was associated with lower rates of circadian misalignment, behavioral, and developmental dysfunctions. The data obtained indicate the need for a detailed study of the state of the circadian system in preschool and primary school children with language difficulties, which will serve as a rationale for the use of chronotherapy principles for the treatment of this neurological dysfunction.

Pro-inflammatory biomarkers and long term neurological outcomes in hypothermia plus melatonin treated asphyxiated newborns. A preliminary approach

OBJECTIVE

To evaluate serum neuronal and inflammatory biomarkers in asphyxiated newborns treated with hypothermia alone or hypothermia plus melatonin, and whether biomarkers correlate with neurodevelopmental outcomes.

DESIGN

A pilot multicentre, randomized, controlled, double blind clinical trial. 25 newborns were recruited. Neonatal neural biomarkers were measured in serum samples at hospital admission (T0), 24 h (T1), 72 hours (T2) and 7-10 days of age (T3). Neurodevelopmental scales were performed at 6 and 18 months. Treated patients received a daily dose of intravenous melatonin, for 3 days.

RESULTS

In melatonin-treated group, lower plasma levels of GM-CSF, IL-2 and IL-13 at T1 were measured vs placebo-group. We also corroborated, at T2, lower concentrations of GM-CSF, as well as IL-7 and IL-13 at T3. Throughout the study period, we found a significant decrease in GM-CSF concentrations in the treatment group. We have also observed sustained decrease over time of GM-CSF and inflammatory cytokines IL-2, IL-7 and IL-13 correlates with better neurodevelopmental outcomes at 6 and 18 months.

CONCLUSIONS

In neonates affected by hypoxic-ischemic encephalopathy, the addition of iv melatonin to hypothermia therapy affects plasma biomarker concentration in the first week of life, with a high correlation with long-term neurological prognosis.

IMPACT

Several plasma cytokines act as inflammatory mediators and biomarkers of hypoxia-ischemia-acquired neonatal brain damage. In animal research, melatonin has been shown to be a safe substance with proven anti-inflammatory and neuroprotective effects. Findings from our clinical trial show that melatonin affects plasma inflammatory biomarker concentration within the first week of life. This effect may be related to long-term neurological prognosis. To date, this is the only clinical trial in human infants including asphyxiated neonates treated with hypothermia and intravenous melatonin. Our study could help design future larger, well-designed clinical trials to clarify its effects in asphyxiated neonates.

Antioxidant Therapy in Neonatal Hypoxic Ischemic Encephalopathy: Adjuvant or Future Alternative to Therapeutic Hypothermia?

BACKGROUND

Oxidative stress-related diseases in newborns arise from pro-oxidant/antioxidant imbalance in both term and preterm neonates. Pro-oxidant/antioxidant imbalance has shown to be present in different pathological conditions such as hypoxic ischemic encephalopathy (HIE), retinopathy of prematurity (ROP), bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC), and patent ductus arteriosus (PDA).

METHODS AND RESULTS

We performed a narrative review according to the most recent available literature (2012-2024), using Scopus and PubMed as electronic databases. Many observational and experimental studies in vitro and in vivo have evaluated the effectiveness of antioxidant therapies such as melatonin, erythropoietin (EPO), allopurinol, N-acetylcisteine (NAS), and nitric oxide synthase (NOS) inhibitors in these diseases. Perinatal asphyxia is one of the most important causes of mortality and morbidity in term and near-term newborns. Therapeutic hypothermia (TH) is the gold standard treatment for neonates with moderate-severe perinatal asphyxia, resulting in a reduction in the mortality and neurodevelopmental disability rates.

CONCLUSIONS

According to the most recent literature and clinical trials, melatonin, allopurinol, NAS, NOS inhibitors, magnesium sulfate, and stem cells stand out as promising as both adjuvants and future probable alternatives to TH in the treatment of HIE.

Neonatal encephalopathy due to suspected hypoxic ischemic encephalopathy: pathophysiology, current, and emerging treatments

BACKGROUND

Neonatal encephalopathy (NE) due to suspected hypoxic-ischemic encephalopathy (HIE), referred to as NESHIE, is a clinical diagnosis in late preterm and term newborns. It occurs as a result of impaired cerebral blood flow and oxygen delivery during the peripartum period and is used until other causes of NE have been discounted and HIE is confirmed. Therapeutic hypothermia (TH) is the only evidence-based and clinically approved treatment modality for HIE. However, the limited efficacy and uncertain benefits of TH in some low- to middle-income countries (LMICs) and the associated need for intensive monitoring have prompted investigations into more accessible and effective stand-alone or additive treatment options.

DATA SOURCES

This review describes the rationale and current evidence for alternative treatments in the context of the pathophysiology of HIE based on literatures from Pubmed and other online sources of published data.

RESULTS

The underlining mechanisms of neurotoxic effect, current clinically approved treatment, various categories of emerging treatments and clinical trials for NE are summarized in this review. Melatonin, caffeine citrate, autologous cord blood stem cells, Epoetin alfa and Allopurinal are being tested as potential neuroprotective agents currently.

CONCLUSION

This review describes the rationale and current evidence for alternative treatments in the context of the pathophysiology of HIE. Neuroprotective agents are currently only being investigated in high- and middle-income settings. Results from these trials will need to be interpreted and validated in LMIC settings. The focus of future research should therefore be on the development of inexpensive, accessible monotherapies and should include LMICs, where the highest burden of NESHIE exists.

Long-Term Outcomes Following Hypoxic Ischemic Encephalopathy

Hypoxic ischemic encephalopathy (HIE) is the most common cause of neonatal encephalopathy and results in significant morbidity and mortality. Long-term outcomes of the condition encompass impairments across all developmental domains. While therapeutic hypothermia (TH) has improved outcomes for term and late preterm infants with moderate to severe HIE, trials are ongoing to investigate the use of TH for infants with mild or preterm HIE. There is no evidence that adjuvant therapies in combination with TH improve long-term outcomes. Numerous trials of various adjuvant therapies are underway in the quest to further improve outcomes for infants with HIE.

Contribution of microglia to the epileptiform activity that results from neonatal hypoxia

Microglia are described as the immune cells of the brain, their immune properties have been extensively studied since first described, however, their neural functions have only been explored over the last decade. Microglia have an important role in maintaining homeostasis in the central nervous system by surveying their surroundings to detect pathogens or damage cells. While these are the classical functions described for microglia, more recently their neural functions have been defined; they are critical to the maturation of neurons during embryonic and postnatal development, phagocytic microglia remove excess synapses during development, a process called synaptic pruning, which is important to overall neural maturation. Furthermore, microglia can respond to neuronal activity and, together with astrocytes, can regulate neural activity, contributing to the equilibrium between excitation and inhibition through a feedback loop. Hypoxia at birth is a serious neurological condition that disrupts normal brain function resulting in seizures and epilepsy later in life. Evidence has shown that microglia may contribute to this hyperexcitability after neonatal hypoxia. This review will summarize the existing data on the role of microglia in the pathogenesis of neonatal hypoxia and the plausible mechanisms that contribute to the development of hyperexcitability after hypoxia in neonates. This article is part of the Special Issue on "Microglia".

Lower plasma melatonin levels in non-hypoxic premature newborns associated with neonatal pain

We analyzed plasma melatonin levels in different groups of preterm newborns without hypoxia and their relationship with several perinatal variables like gestational age or neonatal pain. Prospective cohort study of preterm newborns (PTNB) without perinatal hypoxia, Apgar > 6 at 5 min, and oxygen needs on the third day of life. We compared melatonin levels at day 3 of life in different groups of non-hypoxic preterm infants (Student's t-tests, Mann-Whitney U, and chi2) and analyzed the relationship of melatonin with GA, birth weight, neonatal pain (Premature Infant Pain Profile (PIPP) scale), caffeine treatment, parenteral nutrition, or the development of free radical diseases (correlation study, linear regression) and factors associated with moderate/intense pain and free radical diseases (logistic regression analysis). Sixty-one preterm infants with gestational age (GA) of 30.7 ± 2.0 weeks with no oxygen requirements at day 3 of life were studied with plasma melatonin levels of 33.8 ± 12.01 pg/ml. Preterm infants weighing < 1250 g at birth had lower plasma melatonin levels (p = 0.05). Preterm infants with moderate or severe pain (PPIPP > 5) have lower melatonin levels (p = 0.01), and being preterm with PIPP > 5 is associated with lower plasma melatonin levels (p = 0.03). Being very preterm (GA < 32 GS), having low weight for gestational age (LWGA), receiving caffeine treatment, or requiring parenteral nutrition did not modify melatonin levels in non-hypoxic preterm infants (p = NS). Melatonin on day 3 of life in non-hypoxic preterm infants is not associated with later development of free radical diseases (BPD, sepsis, ROP, HIV, NEC).

CONCLUSION

We observed that preterm infants with moderate to severe pain have lower melatonin levels. These findings are relevant because they reinforce the findings of other authors that melatonin supplementation decreases pain and oxidative stress in painful procedures in premature infants. Further studies are needed to evaluate whether melatonin could be used as an analgesic in painful procedures in preterm infants.

TRIAL REGISTRATION

Trial registration was not required since this was an observational study.

WHAT IS KNOWN

• Melatonin is a potent antioxidant and free radical scavenger in newborns under stress conditions: hypoxia, acidosis, hypotension, painful procedures, or parenteral nutrition. • Pain stimulates the production of melatonin. • Various studies conclude that melatonin administration decreases pain during the neonatal period.

WHAT IS NEW

• Non-hypoxic preterm infants with moderate to severe pain (PIPP>5) have lower levels of melatonin. • Administration of caffeine and treatment with parenteral nutrition do not modify melatonin levels in non-hypoxic preterm infants.

Comparison of Different Adjuvant Therapies for Hypothermia in Neonates with Hypoxic-Ischemic Encephalopathy: A Systematic Review and Network Meta-Analysis

OBJECTIVES

Neonatal hypoxic-ischemic encephalopathy is a major cause of perinatal death and neurodevelopmental impairment (NDI). Hypothermia (HT) is the standard of care; however, additional neuroprotective agents are required to improve prognosis. The authors searched for all drugs in combination with HT and compared their effects using a network meta-analysis.

METHODS

The authors searched PubMed, Embase, and Cochrane Library until September 24, 2022 for articles assessing mortality, NDI, seizures, and abnormal brain imaging findings in neonates with hypoxic-ischemic encephalopathy. Direct pairwise comparisons and a network meta-analysis was performed under random effects.

RESULTS

Thirteen randomized clinical trials enroled 902 newborns treated with six combination therapies: erythropoietin magnesium sulfate, melatonin (MT), topiramate, xenon, and darbepoetin alfa. The results of all comparisons were not statistically significant, except for NDI, HT vs. MT+HT: odds ratio = 6.67, 95% confidence interval = 1.14-38.83; however, the overall evidence quality was low for the small sample size.

CONCLUSIONS

Currently, no combination therapy can reduce mortality, seizures, or abnormal brain imaging findings in neonatal hypoxic-ischemic encephalopathy. According to low quality evidence, HT combined with MT may reduce NDI.

Emerging therapeutic strategies in hypoxic-ischemic encephalopathy: a focus on cognitive outcomes

Perinatal hypoxia-ischemia represents a significant risk to CNS development, leading to high mortality rates, diverse damages, and persistent neurological deficits. Despite advances in neonatal medicine in recent decades, the incidence of HIE remains substantial. Motor deficits can manifest early, while cognitive impairments may be diagnosed later, emphasizing the need for extended follow-up. This review aims to explore potential candidates for therapeutic interventions for hypoxic-ischemic encephalopathy (HIE), with a focus on cognitive deficits. We searched randomized clinical trials (RCT) that tested drug treatments for HIE and evaluated cognitive outcomes. The results included studies on erythropoietin, melatonin, magnesium sulfate, topiramate, and a combination of vitamin C and ibuprofen. Although there are several indications of the efficacy of these drugs among animal models, considering neuroprotective properties, the RCTs failed to provide complete effectiveness in the context of cognitive impairments derived from HIE. More robust RCTs are still needed to advance our knowledge and to establish standardized treatments for HIE.

Potential Adjuncts to Therapeutic Hypothermia to Mitigate Multiorgan Injury in Perinatal Hypoxia-Ischemia

Over the last 2 decades, therapeutic hypothermia has become the standard of care to reduce morbidity and mortality in neonates affected by moderate-to-severe hypoxic-ischemic encephalopathy (HIE). There is a significant interest in improving the neurologic outcomes of neonatal HIE, ranging from adjunctive therapy to therapeutic hypothermia. Importantly, the pathophysiologic mechanisms underlying HIE also affect multiple other organs, contributing to high morbidity and mortality in this patient population. This review focuses on the adjunct therapies currently under investigation to mitigate the impact of hypoxic-ischemic injury on the brain, kidneys, liver, heart, and gastrointestinal system.

Progress in the treatment of neonatal hypoxic-ischemic encephalopathy with umbilical cord blood mononuclear cells

Neonatal hypoxic-ischemic encephalopathy (HIE) is a common disease among newborns, which is a leading cause of neonatal death and permanent neurological sequelae. Therapeutic hypothermia (TH) is the only method for the treatment of HIE that has been recognized effective clinically at home and abroad, but the efficacy is limited. Recent research suggests that the cord blood-derived mononuclear cells (CB-MNCs), which the refer to blood cells containing one nucleus in the cord blood, exert anti-oxidative, anti-inflammatory, anti-apoptotic effects and play a neuroprotective role in HIE. This review focuses on safety and efficacy, the route of administration, dose, timing and combination treatment of CB-MNCs in HIE.

Perinatal asphyxia and hypothermic treatment from the endocrine perspective

Introduction

Perinatal asphyxia is one of the three most important causes of neonatal mortality and morbidity. Therapeutic hypothermia represents the standard treatment for infants with moderate-severe perinatal asphyxia, resulting in reduction in the mortality and major neurodevelopmental disability. So far, data in the literature focusing on the endocrine aspects of both asphyxia and hypothermia treatment at birth are scanty, and many aspects are still debated. Aim of this narrative review is to summarize the current knowledge regarding the short- and long-term effects of perinatal asphyxia and of hypothermia treatment on the endocrine system, thus providing suggestions for improving the management of asphyxiated children.

Results

Involvement of the endocrine system (especially glucose and electrolyte disturbances, adrenal hemorrhage, non-thyroidal illness syndrome) can occur in a variable percentage of subjects with perinatal asphyxia, potentially affecting mortality as well as neurological outcome. Hypothermia may also affect endocrine homeostasis, leading to a decreased incidence of hypocalcemia and an increased risk of dilutional hyponatremia and hypercalcemia.

Conclusions

Metabolic abnormalities in the context of perinatal asphyxia are important modifiable factors that may be associated with a worse outcome. Therefore, clinicians should be aware of the possible occurrence of endocrine complication, in order to establish appropriate screening protocols and allow timely treatment.

[Research research on the use of melatonin in combination with therapeutic hypothermia for the treatment of neonatal hypoxic-ischemic encephalopathy]

Neonatal hypoxic-ischemic encephalopathy (HIE) remains one of the leading causes of death and long-term neurodevelopmental disorders in full-term neonates, and there is currently no curative treatment. Therapeutic hypothermia is now a standard therapy for HIE in the neonatal intensive care unit, but its safety and efficacy in remote areas remains unclear. Melatonin is an indole endocrine hormone mainly produced by the pineal gland and it has the ability to easily penetrate the blood-brain barrier. Through receptor and non-receptor mechanisms, melatonin exerts anti-oxidative and anti-inflammatory effects and participates in the regulation of organelle function and the inhibition of cell death. Melatonin is considered one of the most promising drugs for the treatment of HIE based on its reliable safety profile and clinical/preclinical results. This article reviews the recent research on the use of melatonin in combination with therapeutic hypothermia for the treatment of neonatal HIE.

Traumatic Brain Injury, Sleep, and Melatonin-Intrinsic Changes with Therapeutic Potential

Traumatic brain injury (TBI) is one of the most prevalent causes of morbidity in the United States and is associated with numerous chronic sequelae long after the point of injury. One of the most common long-term complaints in patients with TBI is sleep dysfunction. It is reported that alterations in melatonin follow TBI and may be linked with various sleep and circadian disorders directly (via cellular signaling) or indirectly (via free radicals and inflammatory signaling). Work over the past two decades has contributed to our understanding of the role of melatonin as a sleep regulator and neuroprotective anti-inflammatory agent. Although there is increasing interest in the treatment of insomnia following TBI, a lack of standardization and rigor in melatonin research has left behind a trail of non-generalizable data and ambiguous treatment recommendations. This narrative review describes the underlying biochemical properties of melatonin as they are relevant to TBI. We also discuss potential benefits and a path forward regarding the therapeutic management of TBI with melatonin treatment, including its role as a neuroprotectant, a somnogen, and a modulator of the circadian rhythm.

Melatonin: A Potential Candidate for the Treatment of Experimental and Clinical Perinatal Asphyxia

Perinatal asphyxia is considered to be one of the major causes of brain neurodegeneration in full-term newborns. The worst consequence of perinatal asphyxia is neurodegenerative brain damage, also known as hypoxic-ischemic encephalopathy. Hypoxic-ischemic encephalopathy is the leading cause of mortality in term newborns. To date, due to the complex mechanisms of brain damage, no effective or causal treatment has been developed that would ensure complete neuroprotection. Although hypothermia is the standard of care for hypoxic-ischemic encephalopathy, it does not affect all changes associated with encephalopathy. Therefore, there is a need to develop effective treatment strategies, namely research into new agents and therapies. In recent years, it has been pointed out that natural compounds with neuroprotective properties, such as melatonin, can be used in the treatment of hypoxic-ischemic encephalopathy. This natural substance with anti-inflammatory, antioxidant, anti-apoptotic and neurofunctional properties has been shown to have pleiotropic prophylactic or therapeutic effects, mainly against experimental brain neurodegeneration in hypoxic-ischemic neonates. Melatonin is a natural neuroprotective hormone, which makes it promising for the treatment of neurodegeneration after asphyxia. It is supposed that melatonin alone or in combination with hypothermia may improve neurological outcomes in infants with hypoxic-ischemic encephalopathy. Melatonin has been shown to be effective in the last 20 years of research, mainly in animals with perinatal asphyxia but, so far, no clinical trials have been performed on a sufficient number of newborns. In this review, we summarize the advantages and limitations of melatonin research in the treatment of experimental and clinical perinatal asphyxia.

Brain Damage in the Preterm Infant: Clinical Aspects and Recent Progress in the Prevention and Treatment

Although the prevalence of brain injury and related neurodevelopmental disabilities resulting from preterm birth are major public health concerns, there are no definite neuroprotective strategies to prevent or reduce brain injury. The pattern of brain injury seen in preterm infants has evolved into more subtle lesions that are still essential to diagnose regarding neurodevelopmental outcomes. There is no specific effective method for the treatment of premature infant brain injury, and the focus of clinical treatment is still on prevention. Prevention of this injury requires insight into the pathogenesis, but many gaps exist in our understanding of how neonatal treatment procedures and medications impact cerebral hemodynamics and preterm brain injury. Many studies provide evidence about the prevention of premature infant brain injury, which is related to some drugs (such as erythropoietin, melatonin, mesenchymal stem cells, etc.). However, there are still some controversies about the quality of research and the effectiveness of therapy. This review aims to recapitulate the results of preclinical studies and provide an update on the latest developments around etiological pathways, prevention, and treatment.

Neuroprotective therapies in the NICU in term infants: present and future

Outcomes of neonatal encephalopathy (NE) have improved since the widespread implementation of therapeutic hypothermia (TH) in high-resource settings. While TH for NE in term and near-term infants has proven beneficial, 30-50% of infants with moderate-to-severe NE treated with TH still suffer death or significant impairments. There is therefore a critical need to find additional pharmacological and non-pharmacological interventions that improve the outcomes for these children. There are many potential candidates; however, it is unclear whether these interventions have additional benefits when used with TH. Although primary and delayed (secondary) brain injury starting in the latent phase after HI are major contributors to neurodisability, the very late evolving effects of tertiary brain injury likely require different interventions targeting neurorestoration. Clinical trials of seizure management and neuroprotection bundles are needed, in addition to current trials combining erythropoietin, stem cells, and melatonin with TH. IMPACT: The widespread use of therapeutic hypothermia (TH) in the treatment of neonatal encephalopathy (NE) has reduced the associated morbidity and mortality. However, 30-50% of infants with moderate-to-severe NE treated with TH still suffer death or significant impairments. This review details the pathophysiology of NE along with the evidence for the use of TH and other beneficial neuroprotective strategies used in term infants. We also discuss treatment strategies undergoing evaluation at present as potential adjuvant treatments to TH in NE.

Melatonin Supplementation in Undetermined Pediatric Deaths

Since 2015, the North Carolina Office of the Chief Medical Examiner has investigated seven deaths of infants and toddlers, ages 2 months to 3 years, with exogenous melatonin detected upon toxicological analysis. Melatonin concentrations ranged from 3-1400 ng/mL in postmortem whole blood. While the cause and the manner of all seven deaths were classified as undetermined, the analytical findings are noteworthy. Melatonin is generally considered a safe, natural product appearing in many over-the-counter supplements geared towards young children to facilitate calmness and improve sleep. Melatonin is a neurohormone, which regulates not only circadian rhythms and natural sleep, but other physiological functions. Endogenous melatonin production, derived from essential amino acid metabolism, does not begin until pineal gland maturation at around three months of age with concentrations in plasma peaking during periods of darkness at approximately 0.2 ng/mL. Administering commercially available melatonin supplements to infants results in levels orders of magnitude greater than endogenous sources which should not be assumed to be safe just because of its endogenous nature. The finding of exogenous concentrations in some postmortem pediatric cases warrants attention. Several topics of interest surrounding these postmortem melatonin findings will be considered, such as minimal regulatory control over commercial products as well as the potential impact on hazardous sleeping conditions. This manuscript will outline the physiological effects of melatonin and detail the case studies from the NC medical examiner system. Forensic toxicology laboratories should consider including melatonin at exogenous concentrations in their testing schemes for appropriate postmortem infant and toddler cases.

New possibilities for neuroprotection in neonatal hypoxic-ischemic encephalopathy

Around 0.75 million babies worldwide suffer from moderate or severe hypoxic-ischemic encephalopathy (HIE) each year resulting in around 400,000 babies with neurodevelopmental impairment. In 2010, neonatal HIE was associated with 2.4% of the total Global Burden of Disease. Therapeutic hypothermia (TH), a treatment that is now standard of care in high-income countries, provides proof of concept that strategies that aim to improve neurodevelopment are not only possible but can also be implemented to clinical practice. While TH is beneficial, neonates with moderate or severe HIE treated with TH still experience devastating complications: 48% (range: 44-53) combined death or moderate/severe disability. There is a concern that TH may not be effective in low- and middle-income countries. Therapies that further improve outcomes are desperately needed, and in high-income countries, they must be tested in conjunction with TH. We have in this review focussed on pharmacological treatment options (e.g. erythropoietin, allopurinol, melatonin, cannabidiol, exendin-4/exenatide). Erythropoietin and allopurinol show promise and are progressing towards the clinic with ongoing definitive phase 3 randomised placebo-controlled trials. However, there remain global challenges for the next decade. Conclusion: There is a need for more optimal animal models, greater industry support/sponsorship, increased use of juvenile toxicology, dose-ranging studies with pharmacokinetic-pharmacodynamic modelling, and well-designed clinical trials to avoid exposure to harmful medications or abandoning putative treatments. What is Known: • Therapeutic hypothermia is beneficial in neonatal hypoxic-ischemic encephalopathy. • Neonates with moderate or severe hypoxic-ischemic encephalopathy treated with therapeutic hypothermia still experience severe sequelae. What is New: • Erythropoietin, allopurinol, melatonin, cannabidiol, and exendin-4/exenatide show promise in conjunction with therapeutic hypothermia. • There is a need for more optimal animal models, greater industry support/sponsorship, increased use of juvenile toxicology, dose-ranging studies with pharmacokinetic-pharmacodynamic modelling, and well-designed clinical trials.

Melatonin for Neonatal Encephalopathy: From Bench to Bedside

Neonatal encephalopathy is a leading cause of morbidity and mortality worldwide. Although therapeutic hypothermia (HT) is now standard practice in most neonatal intensive care units in high resource settings, some infants still develop long-term adverse neurological sequelae. In low resource settings, HT may not be safe or efficacious. Therefore, additional neuroprotective interventions are urgently needed. Melatonin's diverse neuroprotective properties include antioxidant, anti-inflammatory, and anti-apoptotic effects. Its strong safety profile and compelling preclinical data suggests that melatonin is a promising agent to improve the outcomes of infants with NE. Over the past decade, the safety and efficacy of melatonin to augment HT has been studied in the neonatal piglet model of perinatal asphyxia. From this model, we have observed that the neuroprotective effects of melatonin are time-critical and dose dependent. Therapeutic melatonin levels are likely to be 15-30 mg/L and for optimal effect, these need to be achieved within the first 2-3 h after birth. This review summarises the neuroprotective properties of melatonin, the key findings from the piglet and other animal studies to date, and the challenges we face to translate melatonin from bench to bedside.

Melatonin for neuroprotection in neonatal encephalopathy: A systematic review & meta-analysis of clinical trials

OBJECTIVE

Melatonin has shown neuroprotective properties in pre-clinical studies of perinatal asphyxia through antioxidant, anti-apoptotic and anti-inflammatory actions. Studies have also demonstrated its safety and efficacy in neonatal encephalopathy (NE). However, its role in the current era of therapeutic hypothermia (HT) is unclear. The review aims to describe the currently available clinical evidence for Melatonin as a potential therapy for NE.

METHODS

Data Sources: We searched Medline, EMBASE, CINAHL, LILACS, and Cochrane central databases, published journals, and conference proceedings from inception to May 31, 2020.

STUDY SELECTION

Randomized controlled trials (RCTs) of Melatonin for NE in term or late preterm infants reporting neurodevelopmental outcomes, death, or both. The evidence quality was evaluated using the GRADE system, while the recommendations were taken according to the quality.

RESULTS

We included five RCTs involving 215 neonates. Long-term development outcome data is lacking in all except in one small study, reporting significantly higher composite cognition scores at 18 months. One study reported intermediate 6-month favorable development on follow-up. Meta-analysis of mortality in combined HT + Melatonin group vs HT alone (Studies = 2, participants = 54) demonstrated no significant reduction with relative risk (RR) 0.42; 95%CI, 0.99-1.12). The overall GRADE evidence quality was very low for a very small sample size. We did not meta-analyze the data for Melatonin alone therapy without HT, as the included studies were of very low quality.

CONCLUSIONS

Despite strong experimental data supporting the role of Melatonin as a neuroprotective agent in NE (both alone and as an adjunct with therapeutic hypothermia), the clinical data supporting the neuroprotective effects in neonates is limited. Larger well designed, adequately powered multicentre clinical trials are urgently needed to define the neuroprotective role of Melatonin in optimizing outcomes of NE.

A Metabolomic Approach in Search of Neurobiomarkers of Perinatal Asphyxia: A Review of the Current Literature

Perinatal asphyxia and the possible sequelae of hypoxic-ischemic encephalopathy (HIE), are associated with high morbidity and mortality rates. The use of therapeutic hypothermia (TH) commencing within the first 6 h of life-currently the only treatment validated for the management of HIE-has been proven to reduce the mortality rate and disability seen at follow up at 18 months. Although there have been attempts to identify neurobiomarkers assessing the severity levels in HIE; none have been validated in clinical use to date, and the lack thereof limits the optimal treatment for these vulnerable infants. Metabolomics is a promising field of the "omics technologies" that may: identify neurobiomarkers, help improve diagnosis, identify patients prone to developing HIE, and potentially improve targeted neuroprotection interventions. This review focuses on the current evidence of metabolomics, a novel tool which may prove to be a useful in the diagnosis, management and treatment options for this multifactorial complex disease. Some of the most promising metabolites analyzed are the group of acylcarnitines: Hydroxybutyrylcarnitine (Malonylcarnitine) [C3-DC (C4-OH)], Tetradecanoylcarnitine [C14], L-Palmitoylcarnitine [C16], Hexadecenoylcarnitine [C16:1], Stearoylcarnitine [C18], and Oleoylcarnitine [C18:1]. A metabolomic "fingerprint" or "index," made up of 4 metabolites (succinate × glycerol/(β-hydroxybutyrate × O-phosphocholine)), seems promising in identifying neonates at risk of developing severe HIE.

Perinatal hypoxic-ischemic damage: review of the current treatment possibilities

Neonatal hypoxic-ischemic encephalopathy is a disorder with heterogeneous manifestation due to asphyxia during perinatal period. It affects approximately 3-12 children per 1000 live births and cause death of 1 million neonates worldwide per year. Besides, motor disabilities, seizures, impaired muscle tone and epilepsy are few of the consequences of hypoxic-ischemic encephalopathy. Despite an extensive research effort regarding various treatment strategies, therapeutic hypothermia with intensive care unit supportive treatment remains the only approved method for neonates who have suffered from moderate to severe hypoxic-ischemic encephalopathy. However, these protocols are only partially effective given that many infants still suffer from severe brain damage. Thus, further research to systematically test promising neuroprotective treatments in combination with hypothermia is essential. In this review, we discussed the pathophysiology of hypoxic-ischemic encephalopathy and delved into different promising treatment modalities, such as melatonin and erythropoietin. However, preclinical studies and clinical trials are still needed to further elucidate the mechanisms of action of these modalities.

Possible Protective Role of Melatonin in Pediatric Infectious Diseases and Neurodevelopmental Pathologies

Melatonin, produced in every cell that possesses mitochondria, acts as an endogenous free radical scavenger, and improves energetic metabolism and immune function, by complex molecular crosstalk with other intracellular compounds. There is greatly increasing evidence regarding beneficial effects of acute and chronic administration of high melatonin doses, in infectious, developmental, and degenerative pathologies, as an endothelial cell and every cell protectant.