Neonatal Encephalopathy: Update on Therapeutic Hypothermia and Other Novel Therapeutics

Impact of dexmedetomidine during hypothermia on initiation of enteral feeding in newborns with hypoxic-ischemic encephalopathy

BackgroundAfter early studies suggested safety and potential for benefit of dexmedetomidine use in neonatal hypoxic-ischemic encephalopathy (HIE), our neonatal intensive care unit (NICU) decided to transition from morphine to dexmedetomidine as our standard sedative during therapeutic hypothermia (TH). The primary aim was to monitor the possible side effects of transitioning from morphine to dexmedetomidine with a primary goal of reducing the days to initiation of enteral feeds to less than 3 days, with the hypothesis that the gastrointestinal motility effects of morphine may have been hindering feeding progress during TH. The secondary aim was to determine rates of hemodynamically significant bradycardia.MethodsThis was a prospective quality improvement study using a retrospective comparison group to determine the comfort, hemodynamic, and early feeding effects of a clinical change in sedation management from morphine to dexmedetomidine. We included infants born at ≥35 weeks of gestation receiving hypothermia for hypoxic-ischemic encephalopathy (HIE) from 2017 to 2023.ResultsData were collected from 107 infants: 48 morphine, 35 dexmedetomidine, and 24 neither. Heart rate was lower in the morphine and dexmedetomidine groups compared to no sedation. Blood pressures, pain scores, and blanket temperatures were not different between groups. Infants receiving dexmedetomidine initiated enteral feeds earlier than either of the other groups and reached full enteral feeds earlier than the no treatment group but not the morphine group.ConclusionsThis study supports a growing body of literature suggesting dexmedetomidine is a well-tolerated alternative to opioids during hypothermia for HIE.

Constraint-Induced Movement Therapy (CIMT) and Neural Precursor Cell (NPC) Transplantation Synergistically Promote Anatomical and Functional Recovery in a Hypoxic-Ischemic Mouse Model

Cerebral palsy (CP) is a common neurodevelopmental disorder characterized by pronounced motor dysfunction and resulting in physical disability. Neural precursor cells (NPCs) have shown therapeutic promise in mouse models of hypoxic-ischemic (HI) perinatal brain injury, which mirror hemiplegic CP. Constraint-induced movement therapy (CIMT) enhances the functional use of the impaired limb and has emerged as a beneficial intervention for hemiplegic CP. However, the precise mechanisms and optimal application of CIMT remain poorly understood. The potential synergy between a regenerative approach using NPCs and a rehabilitation strategy using CIMT has not been explored. We employed the Rice-Vannucci HI model on C57Bl/6 mice at postnatal day (PND) 7, effectively replicating the clinical and neuroanatomical characteristics of hemiplegic CP. NPCs were transplanted in the corpus callosum (CC) at PND21, which is the age corresponding to a 2-year-old child from a developmental perspective and until which CP is often not formally diagnosed, followed or not by Botulinum toxin injections in the unaffected forelimb muscles at PND23, 26, 29 and 32 to apply CIMT. Both interventions led to enhanced CC myelination and significant functional recovery (as shown by rearing and gait analysis testing), through the recruitment of endogenous oligodendrocytes. The combinatorial treatment indicated a synergistic effect, as shown by newly recruited oligodendrocytes and functional recovery. This work demonstrates the mechanistic effects of CIMT and NPC transplantation and advocates for their combined therapeutic potential in addressing hemiplegic CP.

Effectiveness and Safety of Dexmedetomidine in Neonates With Hypoxic Ischemic Encephalopathy Undergoing Therapeutic Hypothermia

OBJECTIVE

The objective of this study was to evaluate and compare the effectiveness and safety of dexmedetomidine as monotherapy between neonates with mild hypoxic ischemic encephalopathy (HIE) and moderate to severe HIE treated with therapeutic hypothermia (TH).

METHODS

This retrospective study included neonates of gestational age ≥36 weeks with a diagnosis of HIE and undergoing TH between January 2014 and December 2021. Patients were included if they received at least 6 hours of continuous sedation with dexmedetomidine. Baseline characteristics, dose and duration of medication, adverse events, liver and kidney function tests, and hospital course were reviewed.

RESULTS

Of the 97 neonates included, 46 had mild, 42 had moderate, and 9 had severe HIE. Dexmedetomidine was initiated at a median 5 hours of life, and the median infusion duration was 77 (46-87) hours. Fifty-two (53.6%) required at least 1 breakthrough opioid or sedative during the first 24 hours of dexmedetomidine infusion. Overall, 40 patients (41.2%) had at least 1 bradycardia episode with heart rate <80 beats/min and 14 patients (14.4%) had heart rate <70 beats/min. Hypotension was experienced by 7 patients (7.2%). Fifty-two patients (53.6%) were intubated in the delivery room and 33/52 (63.5%) were extubated on day of life 1 during dexmedetomidine infusion.

CONCLUSIONS

Dexmedetomidine as monotherapy was effective and safe sedation for infants with HIE undergoing hypothermia. The most common side effect of dexmedetomidine was bradycardia. -Dexmedetomidine may be considered as first and single agent for neonates with HIE undergoing TH.

Protecting effects of 4-octyl itaconate on neonatal hypoxic-ischemic encephalopathy via Nrf2 pathway in astrocytes

BACKGROUND

Neonatal hypoxic-ischemic encephalopathy (HIE) is one of the most common neurological problems occurring in the perinatal period. However, there still is not a promising approach to reduce long-term neurodevelopmental outcomes of HIE. Recently, itaconate has been found to exhibit anti-oxidative and anti-inflammatory effects. However, the therapeutic efficacy of itaconate in HIE remains inconclusive. Therefore, this study attempts to explore the pathophysiological mechanisms of oxidative stress and inflammatory responses in HIE as well as the potential therapeutic role of a derivative of itaconate, 4-octyl itaconate (4OI).

METHODS

We used 7-day-old mice to induce hypoxic-ischemic (HI) model by right common carotid artery ligation followed by 1 h of hypoxia. Behavioral experiments including the Y-maze and novel object recognition test were performed on HI mice at P60 to evaluate long-term neurodevelopmental outcomes. We employed an approach combining non-targeted metabolomics with transcriptomics to screen alterations in metabolic profiles and gene expression in the hippocampal tissue of the mice at 8 h after hypoxia. Immunofluorescence staining and RT-PCR were used to evaluate the pathological changes in brain tissue cells and the expression of mRNA and proteins. 4OI was intraperitoneally injected into HI model mice to assess its anti-inflammatory and antioxidant effects. BV2 and C8D1A cells were cultured in vitro to study the effect of 4OI on the expression and nuclear translocation of Nrf2. We also used Nrf2-siRNA to further validate 4OI-induced Nrf2 pathway in astrocytes.

RESULTS

We found that in the acute phase of HI, there was an accumulation of pyruvate and lactate in the hippocampal tissue, accompanied by oxidative stress and pro-inflammatory, as well as increased expression of antioxidative stress and anti-inflammatory genes. Treatment of 4OI could inhibit activation and proliferation of microglial cells and astrocytes, reduce neuronal death and relieve cognitive dysfunction in HI mice. Furthermore, 4OI enhanced nuclear factor erythroid-2-related factor (Nfe2l2; Nrf2) expression and nuclear translocation in astrocytes, reduced pro-inflammatory cytokine production, and increased antioxidant enzyme expression.

CONCLUSION

Our study demonstrates that 4OI has a potential therapeutic effect on neuronal damage and cognitive deficits in HIE, potentially through the modulation of inflammation and oxidative stress pathways by Nrf2 in astrocytes.

Cerebral Tissue Oxygen Saturation Measurements in Perinatal Asphyxia Cases Treated with Therapeutic Hypothermia

Cerebral tissue oxygen saturation (CrSO2) measured with near-infrared spectroscopy (NIRS) technology has recently become the subject of several research studies. The aim of this study was to investigate the diagnostic value of CrSO2 measurements in perinatal asphyxia (PA) cases. The study included a patient group of 42 PA cases, who were to be applied with therapeutic hypothermia (TH), and a control group of 42 healthy term newborns. PA cases were determined as moderate or severe encephalopathy (Sarnat score stage II or III) in clinical evaluation. In both groups, left (CrSO2L) and right (CrSO2R) NIRS measurements were taken for 10 minutes on the scalp. The arithmetic mean value of measurements was calculated and compared. The mean measurements were CrSO2R 67.38 ± 9.39 and CrSO2L 66.73 ± 7.76 in the patient group, and CrSO2R 80.28 ± 8.04 and CrSO2L 79.14 ± 8.49 in the control group. The mean CrSO2R and CrSO2L measurements of the patient group were statistically significantly lower than those of the control group (p < 0.001). In the Pearson correlation analysis, a significant correlation was determined in the patient group between cord blood gas pH and CrSO2R (r: 0.539, p < 0.001) and CrSO2L (r: 0.54, p < 0.001). For a cutoff value of CrSO2L ≤ 72%, the positive predictive value was 80 and the negative predictive value was 84.6. For a cutoff value of CrSO2R ≤ 74%, the positive predictive value was 79.5 and the negative predictive value was 82.5. Low CrSO2 measurements obtained with the NIRS method in PA cases to be applied with TH together with cord blood gas parameters can be considered a helpful parameter in diagnosis.

HSPB1 overexpression improves hypoxic-ischemic brain damage by attenuating ferroptosis in rats through promoting G6PD expression

Heat-shock protein B (HSPB1) has a neuroprotective effect on brain injury and is a negative regulator of ferroptosis. Therefore, we infer that HSPB1 plays a protective role in hypoxic-ischemic (HI) brain damage by inhibiting ferroptosis. A neonatal rat model of hypoxic-ischemic (HI) brain damage was established. HSPB1 overexpression plasmid and the negative control were injected into the lateral ventricle of rats 48 h before HI brain damage surgery. HSPB1 and glucose-6-phosphate dehydrogenase (G6PD) levels, infarction rate, iron accumulation, apoptosis, and ferroptosis-related markers were estimated with the assistance of qRT-PCR, 2,3,5-triphenyl tetrazolium chloride (TTC) staining, Prussian blue staining, iron assay kit, TUNEL staining, and Western blot. In vitro, after transfection, HSPB1 and G6PD levels, oxygen-glucose deprivation (OGD)-mediated hippocampal neuron cell viability, apoptosis, iron content, and ferroptosis-related markers were assessed using qRT-PCR, MTT, flow cytometry, iron assay kit, and Western blot. HSPB1 and G6PD were overexpressed in the hippocampus tissues of HI rats. High expression of HSPB1 in HI rats lessened infarction rate and ferritin level, hindered iron accumulation and apoptosis, and promoted GPX4, SLC7A11, and TFR1 levels. In OGD-mediated hippocampal neuron cells, HSPB1 upregulation intensified the viability and repressed apoptosis and ferroptosis, whereas G6PD silencing reversed the effects of HSPB1 upregulation. We documented that HSPB1 overexpression unleashes neuroprotective effects via modulating G6PD expression, which offers a novel target for the prevention and treatment of HI brain damage.NEW & NOTEWORTHY HSPB1 and G6PD were overexpressed in the hippocampus tissues of HI rats. High expression of HSPB1 in HI rats mitigated infarction rate and iron accumulation. HSPB1 overexpression reduced ferritin level, attenuated apoptosis, yet augmented GPX4, SLC7A11, and TFR1 levels in the hippocampus tissues of HI rats. G6PD deletion impaired the protective role of HSPB1 overexpression against HI brain damage-induced ferroptosis.

Cerebral ischemia in the developing brain

Brain ischemia affects all ages, from neonates to the elderly population, and is a leading cause of mortality and morbidity. Multiple preclinical rodent models involving different ages have been developed to investigate the effect of ischemia during different times of key brain maturation events. Traditional models of developmental brain ischemia have focused on rodents at postnatal day 7-10, though emerging models in juvenile rodents (postnatal days 17-25) indicate that there may be fundamental differences in neuronal injury and functional outcomes following focal or global cerebral ischemia at different developmental ages, as well as in adults. Here, we consider the timing of injury in terms of excitation/inhibition balance, oxidative stress, inflammatory responses, blood brain barrier integrity, and white matter injury. Finally, we review translational strategies to improve function after ischemic brain injury, including new ideas regarding neurorestoration, or neural repair strategies that restore plasticity, at delayed time points after ischemia.

microRNA-93 packaged in extracellular vesicles from mesenchymal stem cells reduce neonatal hypoxic-ischemic brain injury

OBJECTIVE

Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have been proposed as a promising strategy for treating ischemia-related diseases. Herein, we probed into the role of miR-93 delivered by BMSC-EVs in hypoxic-ischemic brain injury (HIBD).

METHODS

Neonatal HIBD mouse models and hippocampal neuron models of oxygen glucose deprivation (OGD) were constructed. EVs were isolated from the culture medium of bone marrow MSCs (BMSCs). After co-culture of BMSC-EVs with OGD-exposed hippocampal neurons, the effect of microRNA-93 (miR-93) delivered by BMSC-EVs on OGD-induced hippocampal neurons as well as on HIBD in vivo under transfection of miR-93 mimic or inhibitor was explored. The interaction among miR-93, JMJD3, and p53/KLF2 axis was assessed.

RESULTS

BMSC-EVs prevented OGD-induced hippocampal neuron apoptosis and inflammation, which was associated with their transfer of miR-93 into the hippocampal neurons. miR-93 targeted JMJD3 and downregulated its expression, thus inhibiting the OGD-induced hippocampal neuron apoptosis. By regulating the JMJD3/p53/KLF2 axis, miR-93 in BMSC-EVs reduced the OGD-induced hippocampal neuron apoptosis in vitro as well as alleviating HIBD in vivo.

CONCLUSIONS

The current study highlighted that miR-93 delivered by BMSC-EVs alleviated HIBD in neonatal mice through the JMJD3-dependent p53/KLF2 axis.

Treatments and therapeutic protocols for the recovery of an asphyxiated new-born: A review of pre-clinical and clinical studies in human neonates and in different animal models

The objective of this review is to ascertain the advantages and disadvantages of several treatments and therapeutic protocols that have been used for the prevention and treatment of perinatal asphyxia in human neonates and in different animal models. Perinatal asphyxia is one of the main causes of mortality worldwide and is an important factor in triggering physio-metabolic disorders that result in serious neurological consequences and learning disorders not only in human foetuses and neonates, but also in animals. In recent years, the search for new pharmacological protocols to prevent and reverse physio-metabolic disorders and brain damage derived from perinatal asphyxia has been and continues to be the subject of intense research. Currently, within these pharmacological protocols, therapeutic strategies have been evaluated that use respiratory and hormonal stimulants, as well as hypothermic therapies in combination with other putative neuroprotective agents. Similarly, energy supplements have been evaluated with the objective of preventing perinatal asphyxia and treating new-borns with this condition, and to decrease the incidence of neonatal and foetal deaths associated with it. However, despite these promising advances, this pathology has persisted, since the administration of these therapies in low doses may not exert a neuroprotective effect or, in high doses, can trigger adverse effects (such as reduced cardiac contractility, reduced cerebral blood flow, poor perfusion, sympathetic and neuroendocrine stimulation, and increased blood viscosity) in human foetuses and neonates as well as in different animal models (rats, piglets, sheep and rabbits). Therefore, it is important to determine the minimum effective dose with which these therapies exert a neuroprotective effect, as well as the mode of administration, the duration of therapy, etc. Therefore, until a powerful strategy is found to improve the consequences of suffocation, this topic will continue to be the subject of intensive research in the future.

Effect of dexmedetomidine on heart rate in neonates with hypoxic ischemic encephalopathy undergoing therapeutic hypothermia

BACKGROUND

Sedation is recommended to optimize neuroprotection in neonates with hypoxic ischemic encephalopathy (HIE) undergoing therapeutic hypothermia (TH). Dexmedetomidine is an alternative agent to opioids, which are commonly used but have adverse effects. Both TH and dexmedetomidine can cause bradycardia. In this study, we describe our experience with dexmedetomidine and fentanyl in neonates undergoing TH for HIE, with a focus on heart rate (HR).

METHODS

We performed a retrospective chart review from 2011-2019 at a level IV NICU comparing sedation with dexmedetomidine (n = 14), fentanyl (n = 120), or both (n = 32) during TH for HIE. HR trends were compared based on sedation and gestational age. Neonates were included if they underwent TH and received sedation and were excluded if cooling was initiated past 24hours (h) from birth or if they required ECMO.

RESULTS

Of the 166 neonates included, 46 received dexmedetomidine, 14 as monotherapy and 32 in combination with fentanyl. Mean hourly HR from 12-36 h after birth was significantly lower for infants on dexmedetomidine versus fentanyl monotherapy (91±9 vs. 103±11 bpm, p < 0.002). Dexmedetomidine was decreased or discontinued in 22 (47.8%) neonates, most commonly due to inadequate sedation with a low HR. Lower gestational age was associated with higher HR but no significant difference in dexmedetomidine-related HR trends.

CONCLUSIONS

Despite an association with lower HR, dexmedetomidine may be successfully used in neonates with HIE undergoing TH. Implementation of a standardized protocol may facilitate dexmedetomidine titration in this population.

How Climate Change May Threaten Progress in Neonatal Health in the African Region

Climate change is likely to have wide-ranging impacts on maternal and neonatal health in Africa. Populations in low-resource settings already experience adverse impacts from weather extremes, a high burden of disease from environmental exposures, and limited access to high-quality clinical care. Climate change is already increasing local temperatures. Neonates are at high risk of heat stress and dehydration due to their unique metabolism, physiology, growth, and developmental characteristics. Infants in low-income settings may have little protection against extreme heat due to housing design and limited access to affordable space cooling. Climate change may increase risks to neonatal health from weather disasters, decreasing food security, and facilitating infectious disease transmission. Effective interventions to reduce risks from the heat include health education on heat risks for mothers, caregivers, and clinicians; nature-based solutions to reduce urban heat islands; space cooling in health facilities; and equitable improvements in housing quality and food systems. Reductions in greenhouse gas emissions are essential to reduce the long-term impacts of climate change that will further undermine global health strategies to reduce neonatal mortality.

Free Radicals and Neonatal Brain Injury: From Underlying Pathophysiology to Antioxidant Treatment Perspectives

Free radicals play a role of paramount importance in the development of neonatal brain injury. Depending on the pathophysiological mechanisms underlying free radical overproduction and upon specific neonatal characteristics, such as the GA-dependent maturation of antioxidant defenses and of cerebrovascular autoregulation, different profiles of injury have been identified. The growing evidence on the detrimental effects of free radicals on the brain tissue has led to discover not only potential biomarkers for oxidative damage, but also possible neuroprotective therapeutic approaches targeting oxidative stress. While a more extensive validation of free radical biomarkers is required before considering their use in routine neonatal practice, two important treatments endowed with antioxidant properties, such as therapeutic hypothermia and magnesium sulfate, have become part of the standard of care to reduce the risk of neonatal brain injury, and other promising therapeutic strategies are being tested in clinical trials. The implementation of currently available evidence is crucial to optimize neonatal neuroprotection and to develop individualized diagnostic and therapeutic approaches addressing oxidative brain injury, with the final aim of improving the neurological outcome of this population.

Cognitive outcomes in late childhood and adolescence of neonatal hypoxic-ischemic encephalopathy

Hypoxic-ischemic encephalopathy (HIE) is the most common cause of neonatal encephalopathy with a global incidence of approximately 1 to 8 per 1,000 live births. Neonatal encephalopathy can cause neurodevelopmental and cognitive impairments in survivors of hypoxic-ischemic insults with and without functional motor deficits. Normal neurodevelopmental outcomes in early childhood do not preclude cognitive and behavioral difficulties in late childhood and adolescence because cognitive functions are not yet fully developed at this early age. Therapeutic hypothermia has been shown to significantly reduced death and severe disabilities in term newborns with HIE. However, children treated with hypothermia therapy remain at risk for cognitive impairments and follow-up is necessary throughout late childhood and adolescence. Novel adjunctive neuroprotective therapies combined with therapeutic hypothermia may enhance the survival and neurodevelopmental outcomes of infants with HIE. The extent and severity of brain injury on magnetic resonance imaging might predict neurodevelopmental outcomes and lead to targeted interven tions in children with a history of neonatal encephalopathy. We provide a summary of the long-term cognitive outcomes in late childhood and adolescence in children with a history of HIE and the association between pattern of brain injury and neurodevelopmental outcomes.

Dexmedetomidine versus intermittent morphine for sedation of neonates with encephalopathy undergoing therapeutic hypothermia

OBJECTIVE

In March 2019, the sedative in the therapeutic hypothermia protocol at Bellevue Hospital Center and NYU Langone Health changed from morphine to dexmedetomidine. This study evaluated the impact of this change on efficacy and safety parameters.

STUDY DESIGN

This was a retrospective, observational cohort study including neonates with HIE undergoing therapeutic hypothermia (N = 70) at two regional perinatal medical centers.

RESULTS

Baseline demographics, pain scores, hemodynamics, and time to enteral feeds were similar between dexmedetomidine (N = 34) and morphine (N = 36) patients. Dexmedetomidine patients received more breakthrough morphine (0.13 ± 0.13 vs 0.04 ± 0.09 mg/kg, p = 0.001), but less cumulative morphine (0.13 ± 0.13 vs 1.79 ± 0.23 mg/kg, p < 0.0001). Morphine patients on invasive ventilation required increased support (0 vs 31.58%, p = 0.02).

CONCLUSION

Dexmedetomidine is effective and safe for sedation and analgesia during therapeutic hypothermia. It reduced total opioid usage, with no increased incidence of adverse events.

Multitarget neuroprotection by quercetin: Changes in gene expression in two perinatal asphyxia models

Hypoxic-ischemic encephalopathy (HIE) causes mortality and long-term neurologic morbidities in newborns, affecting pathways related to energy failure, excitotoxicity and oxidative stress that often lead to cell death. The whole process of HIE injury is coupled to changes in the expression of a great array of proteins. A nanoliposomal preparation of the flavonoid quercetin has been shown to exert neuroprotective effects in perinatal asphyxia models. This study aimed to identify neonatal HIE markers and explore the effect of quercetin administration in two perinatal asphyxia models: newborn rats and piglets. In the rat model, nanoliposomal quercetin administration reduced mortality after asphyxia. In the piglet model, quercetin partially overrode the reduction of HIF-1α mRNA levels in the cortex induced by asphyxia. Quercetin administration also reduced increased level of HO-1 mRNA in asphyctic piglets. These results suggest that quercetin neuroprotection might be involved in the regulation of HIF-1α, HO-1 and their targets. A proteomic approach revealed that the glycolytic pathway is strongly regulated by quercetin in both species. We also identified a set of proteins differentially expressed that could be further considered as markers. In piglets, this set includes Acidic Leucine-rich nuclear phosphoprotein 32 (ANP32A), associated with nervous system differentiation, proteins related with death pathways and alpha-enolase which can be converted to neuron-specific enolase, a glycolytic enzyme that may promote neuroprotection. In newborn rats, other promising proteins associated with neurogenesis and neuroprotection emerged, such as dihydropyrimidinase-related proteins, catalytic and regulatory subunits of phosphatases and heterogeneous nuclear ribonucleoprotein K (hnRNPK). Our results show that a nanoliposomal preparation of quercetin, with protective effect in two HIE mammal models, modulates the expression of proteins involved in energy metabolism and other putative neuroprotective signals in the cortex. Identification of these signals could reveal potential molecular pathways involved in disease onset and the novel quercetin neuroprotective strategy.

Quality improvement for reducing utilization drift in hypoxic-ischemic encephalopathy management

OBJECTIVES

Therapeutic hypothermia is an effective neuroprotective intervention for infants with moderate or severe hypoxic-ischemic encephalopathy (HIE). With the introduction of new medical therapy comes a learning curve with regards to its proper implementation and understanding of eligibility guidelines. We hypothesized that variation in patient selection and lack of adherence to established protocols contributed to the utilization drift away from the original eligibility guidelines.

METHODS

A retrospective cohort study was conducted including infants who received therapeutic hypothermia in the neonatal intensive care unit (NICU) for HIE to determine utilization drift. We then used QI methodology to address gaps in medical documentation that may lead to the conclusion that therapeutic hypothermia was inappropriately applied.

RESULTS

We identified 54% of infants who received therapeutic hypothermia who did not meet the clinical, physiologic, and neurologic examination criteria for this intervention based on provider admission and discharge documentation within the electronic medical record (EMR). Review of the charts identified incomplete documentation in 71% of cases and led to the following interventions: 1) implementation of EMR smartphrases; 2) engagement of key stakeholders and education of faculty, residents, and neonatal nurse practitioners; and 3) performance measurement and sharing of data. We were able to improve both adherence to the therapeutic hypothermia guidelines and achieve 100% documentation of the modified Sarnat score.

CONCLUSIONS

Incomplete documentation can lead to the assumption that therapeutic hypothermia was inappropriately applied when reviewing a patient's EMR. However, in actual clinical practice physicians follow the clinical guidelines but are not documenting their medical decision making completely. QI methodology addresses this gap in documentation, which will help determine the true utilization drift of therapeutic hypothermia in future studies.

Early neuroimaging and ultrastructural correlates of injury outcome after neonatal hypoxic-ischaemia

Hypoxic ischaemia encephalopathy is the major cause of brain injury in new-borns. However, to date, useful biomarkers which may be used to early predict neurodevelopmental impairment for proper commencement of hypothermia therapy is still lacking. This study aimed to determine whether the early neuroimaging characteristics and ultrastructural correlates were associated with different injury progressions and brain damage severity outcomes after neonatal hypoxic ischaemia. Longitudinal 7 T MRI was performed within 6 h, 24 h and 7 days after hypoxic ischaemia in rat pups. The brain damage outcome at 7 days post-hypoxic ischaemia assessed using histopathology and MRI were classified as mild, moderate and severe. We found there was a spectrum of different brain damage severity outcomes after the same duration of hypoxic ischaemia. The severity of brain damage determined using MRI correlated well with that assessed by histopathology. Quantitative MRI characteristics denoting water diffusivity in the tissue showed significant differences in the apparent diffusion coefficient deficit volume and deficit ratios within 6 h, at 24 h and 7 days after hypoxic ischaemia among the 3 different outcome groups. The susceptible brain areas to hypoxic ischaemia were revealed by the temporal changes in regional apparent diffusion coefficient values among three outcome groups. Within 6 h post-hypoxic ischaemia, a larger apparent diffusion coefficient deficit volume and deficit ratios and lower apparent diffusion coefficient values were highly associated with adverse brain damage outcome. In the apparent diffusion coefficient deficit areas detected early after hypoxic ischaemia which were highly associated with severe damage outcome, transmission electron microscopy revealed fragmented nuclei; swollen rough endoplasmic reticulum and degenerating mitochondria in the cortex and prominent myelin loss and axon detraction in the white matter. Taken together, different apparent diffusion coefficient patterns obtained early after hypoxic ischaemia are highly associated with different injury progression leading to different brain damage severity outcomes, suggesting the apparent diffusion coefficient characteristics may be applicable to early identify the high-risk neonates for hypothermia therapy.

Pharmacokinetics of Inter-Alpha Inhibitor Proteins and Effects on Hemostasis After Hypoxic-Ischemic Brain Injury in Neonatal Rats

BACKGROUND

Hypoxic-ischemic (HI) brain injury is a leading cause of long-term neurodevelopmental morbidities in neonates. Human plasma-derived Inter-Alpha Inhibitor Proteins (hIAIPs) are neuroprotective after HI brain injury in neonatal rats. The light chain (bikunin) of hIAIPs inhibits proteases involved in the coagulation of blood. Newborns exposed to HI can be at risk for significant bleeding in the brain and other organs.

OBJECTIVE

The objectives of the present study were to assess the pharmacokinetics (PK) and the duration of bleeding after intraperitoneal (IP) administration of hIAIPs in HI-exposed male and female neonatal rats.

METHODS

HI was induced with the Rice-Vannucci method in postnatal (P) day-7 rats. After the right common carotid artery ligation, rats were exposed to 90 min of 8% oxygen. hIAIPs (30 mg/kg, IP) were given immediately after Sham or HI exposure in the PK study and serum was collected 1, 6, 12, 24, or 36 h after the injections. Serum hIAIP concentrations were measured with a competitive ELISA. ADAPT5 software was used to fit the pooled PK data considering first-order absorption and disposition. hIAIPs (60 mg/kg, IP) were given in the bleeding time studies at 0, 24 and 48 h after HI with tail bleeding times measured 72 h after HI.

RESULTS

IP administration yielded significant systemic exposure to hIAIPs with PK being affected markedly including primarily faster absorption and reduced elimination as a result of HI and modestly of sex-related differences. hIAIP administration did not affect bleeding times after HI.

CONCLUSION

These results will help to inform hIAIP dosing regimen schedules in studies of neuroprotection in neonates exposed to HI.

Neuroprotective effects of icariin in neonatal hypoxia-ischemic brain damage via its anti-apoptotic property

INTRODUCTION

Neonatal hypoxic-ischemic brain damage (HIBD) is a brain disease that is caused by perinatal asphyxia. Icariin (ICA), which is an active component of Epimedii (a Chinese medicinal herb), has been verified to demonstrate a wide range of therapeutic effects, such as alleviating various kinds of brain injury.

OBJECTIVE

The current study aims to examine the neuroprotective effects of ICA on neonatal HIBD in mice.

MATERIALS AND METHODS

A modified version of the Rice-Vannucci method was performed to establish neonatal HIBD in 7-day-old mouse pups that were pretreated with ICA or vehicle. The infarct volume was measured, and behavioral tests were conducted to assess the protective effects of ICA on the neonatal brain and to evaluate functional recovery after injury. TUNEL staining was used to detect cell apoptosis, and the levels of cleaved caspase-3 and phosphorylated protein kinase B (Akt) were determined by using Western blot.

RESULTS

We showed that pretreatment with ICA could significantly reduce brain damage, improve neurobehavioral outcomes, and suppress apoptotic cell death following HI injury. ICA reversed the HI-induced reduction in phosphorylated Akt and activation of cleaved caspase-3.

CONCLUSION

The results demonstrate that ICA exerts potential neuroprotective effects on neonatal HIBD, which may be mediated by its anti-apoptotic activity.

Effects of inter-alpha inhibitor proteins on brain injury after exposure of neonatal rats to severe hypoxia-ischemia

Hypoxic-ischemic (HI) brain injury is one of the most common neurological problems occurring in premature and full-term infants after perinatal complications. Hypothermia is the only treatment approved for HI encephalopathy in newborns. However, this treatment is only partially protective, cannot be used to treat premature infants, and has limited efficacy to treat severe HI encephalopathy. Inflammation contributes to the evolution of HI brain injury in neonates. Inter-alpha Inhibitor Proteins (IAIPs) are immunomodulatory proteins that have neuroprotective properties after exposure to moderate HI in neonatal rats. The objective of the current study was to determine the neuroprotective efficacy of treatment with IAIPs starting immediately after or with a delay of one hour after exposure to severe HI of 120 min duration. One hundred and forty-six 7-day-old rat pups were randomized to sham control, HI and immediate treatment with IAIPs (60 mg/kg) or placebo (PL), and sham, HI and delayed treatment with IAIPs or PL. IAIPs or PL were given at zero, 24, and 48 h after HI or 1, 24 and 48 h after HI. Total brain infarct volume was determined 72 h after exposure to HI. Treatment with IAIPs immediately after HI decreased (P < 0.05) infarct volumes by 58.0% and 44.5% in male and female neonatal rats, respectively. Delayed treatment with IAIPs after HI decreased (P < 0.05) infarct volumes by 23.7% in male, but not in female rats. We conclude that IAIPs exert neuroprotective effects even after exposure to severe HI in neonatal rats and appear to exhibit some sex-related differential effects.

Transcriptomic profile of adverse neurodevelopmental outcomes after neonatal encephalopathy

A rapid and early diagnostic test to identify the encephalopathic babies at risk of adverse outcome may accelerate the development of neuroprotectants. We examined if a whole blood transcriptomic signature measured soon after birth, predicts adverse neurodevelopmental outcome eighteen months after neonatal encephalopathy. We performed next generation sequencing on whole blood ribonucleic acid obtained within six hours of birth from the first 47 encephalopathic babies recruited to the Hypothermia for Encephalopathy in Low and middle-income countries (HELIX) trial. Two infants with blood culture positive sepsis were excluded, and the data from remaining 45 were analysed. A total of 855 genes were significantly differentially expressed between the good and adverse outcome groups, of which RGS1 and SMC4 were the most significant. Biological pathway analysis adjusted for gender, trial randomisation allocation (cooling therapy versus usual care) and estimated blood leukocyte proportions revealed over-representation of genes from pathways related to melatonin and polo-like kinase in babies with adverse outcome. These preliminary data suggest that transcriptomic profiling may be a promising tool for rapid risk stratification in neonatal encephalopathy. It may provide insights into biological mechanisms and identify novel therapeutic targets for neuroprotection.

FIRS: Neonatal considerations

Fetal Inflammatory Response Syndrome (FIRS) is the fetal counterpart of systemic inflammatory response syndrome (SIRS) described in adults. When the fetus is directly exposed to inflammation of the fetal membranes or the placental-fetal circulation, and organs are adversely affected, the disorder is known as FIRS. This syndrome can significantly affect multiple organs with significant short and long term implications for the newborn. In cases of neonatal encephalopathy when no obvious etiology is identified, FIRS needs to be considered. Based on the significant incidence of chorioamnionitis and its potential effects on the newborn, any evidence of maternal, fetal, or neonatal infection should mandate further evaluation of the placenta and membrane histopathology.

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

OBJECTIVES

To investigate the effect of adding melatonin to hypothermia treatment on neurodevelopmental outcomes in asphyctic newborns.

DESIGN

Pilot multicenter, randomized, controlled, double-blind clinical trial. Statistical comparison of results obtained in two intervention arms: hypothermia plus placebo and hypothermia plus melatonin.

SETTING

Level 3 neonatal ICU.

PATIENTS

Twenty-five newborns were recruited.

INTERVENTIONS

The hypothermia plus melatonin patients received a daily dose of IV melatonin, 5 mg per kg body weight, for 3 days. General laboratory variables were measured both at neonatal ICU admission and after intervention. All infants were studied with amplitude-integrated electroencephalography and brain MRI within the first week of life. The neurodevelopmental Bayley III test, the Gross Motor Function Classification System, and the Tardieu scale were applied at the ages of 6 and 18 months.

MEASUREMENTS AND MAIN RESULTS

Clinical characteristics, laboratory evaluations, MRI findings, and amplitude-integrated electroencephalography background did not differ between the treatment groups. The newborns in the hypothermia plus melatonin group achieved a significantly higher composite score for the cognitive section of the Bayley III test at 18 months old, with respect to the hypothermia plus placebo group (p = 0.05). There were no differences between the groups according to the Gross Motor Function Classification System and Tardieu motor assessment scales.

CONCLUSIONS

The early addition of IV melatonin to asphyctic neonates is feasible and may improve long-term neurodevelopment. To our knowledge, this is the first clinical trial to analyze the administration of IV melatonin as an adjuvant therapy to therapeutic hypothermia.

A Physiology-Based Pharmacokinetic Framework to Support Drug Development and Dose Precision During Therapeutic Hypothermia in Neonates

Therapeutic hypothermia (TH) is standard treatment for neonates (≥36 weeks) with perinatal asphyxia (PA) and hypoxic-ischemic encephalopathy. TH reduces mortality and neurodevelopmental disability due to reduced metabolic rate and decreased neuronal apoptosis. Since both hypothermia and PA influence physiology, they are expected to alter pharmacokinetics (PK). Tools for personalized dosing in this setting are lacking. A neonatal hypothermia physiology-based PK (PBPK) framework would enable precision dosing in the clinic. In this literature review, the stepwise approach, benefits and challenges to develop such a PBPK framework are covered. It hereby contributes to explore the impact of non-maturational PK covariates. First, the current evidence as well as knowledge gaps on the impact of PA and TH on drug absorption, distribution, metabolism and excretion in neonates is summarized. While reduced renal drug elimination is well-documented in neonates with PA undergoing hypothermia, knowledge of the impact on drug metabolism is limited. Second, a multidisciplinary approach to develop a neonatal hypothermia PBPK framework is presented. Insights on the effect of hypothermia on hepatic drug elimination can partly be generated from in vitro (human/animal) profiling of hepatic drug metabolizing enzymes and transporters. Also, endogenous biomarkers may be evaluated as surrogate for metabolic activity. To distinguish the impact of PA versus hypothermia on drug metabolism, in vivo neonatal animal data are needed. The conventional pig is a well-established model for PA and the neonatal Göttingen minipig should be further explored for PA under hypothermia conditions, as it is the most commonly used pig strain in nonclinical drug development. Finally, a strategy is proposed for establishing and fine-tuning compound-specific PBPK models for this application. Besides improvement of clinical exposure predictions of drugs used during hypothermia, the developed PBPK models can be applied in drug development. Add-on pharmacotherapies to further improve outcome in neonates undergoing hypothermia are under investigation, all in need for dosing guidance. Furthermore, the hypothermia PBPK framework can be used to develop temperature-driven PBPK models for other populations or indications. The applicability of the proposed workflow and the challenges in the development of the PBPK framework are illustrated for midazolam as model drug.

Free radicals and neonatal encephalopathy: mechanisms of injury, biomarkers, and antioxidant treatment perspectives

Neonatal encephalopathy (NE), most commonly a result of the disruption of cerebral oxygen delivery, is the leading cause of neurologic disability in term neonates. Given the key role of free radicals in brain injury development following hypoxia-ischemia-reperfusion, several oxidative biomarkers have been explored in preclinical and clinical models of NE. Among these, antioxidant enzyme activity, uric acid excretion, nitric oxide, malondialdehyde, and non-protein-bound iron have shown promising results as possible predictors of NE severity and outcome. Owing to high costs and technical complexity, however, their routine use in clinical practice is still limited. Several strategies aimed at reducing free radical production or upregulating physiological scavengers have been proposed for NE. Room-air resuscitation has proved to reduce oxidative stress following perinatal asphyxia and is now universally adopted. A number of medications endowed with antioxidant properties, such as melatonin, erythropoietin, allopurinol, or N-acetylcysteine, have also shown potential neuroprotective effects in perinatal asphyxia; nevertheless, further evidence is needed before these antioxidant approaches could be implemented as standard care.

In clinical practice, cerebral MRI in newborns is highly predictive of neurodevelopmental outcome after therapeutic hypothermia

OBJECTIVE

In the trials, a substantial proportion of newborns who underwent therapeutic hypothermia (TH) had an adverse outcome after hypoxic-ischaemic encephalopathy (HIE). Cooled babies were noted to have fewer cerebral lesions on MRI but when present lesions were predictive of adverse outcome. We investigate the predictive value of cerebral MRI in babies who undergo cooling in the clinical setting outside of the clinical trials in a prospective UK cohort.

RESULTS

Of 75 babies recruited from four centres, neurodevelopment was available for 69 (92%) with 29% (20/69) being abnormal. The unfavourable MRI group (n = 22) had significantly lower motor (p < 0.001), language (p < 0.001) and cognition (p < 0.001) scores on Bayley-III assessment, compared to the favourable MRI group (n = 47). On multiple regression there was a significant relationship between basal ganglia and thalami abnormality and motor (p = 0.002), cognition (p = 0.011) and language (p = 0.013) outcomes. Half of the babies who had an MRI predictive of adverse outcome (11/22) had highest grade cerebral palsy. Cerebral MRI had 95% sensitivity, 94% specificity, 91% PPV and 98% NPV in predicting neurodevelopment.

CONCLUSIONS

In this clinical cohort, fewer children had adverse neurodevelopment after TH compared to the TH trials. However, half the children who had an MRI predictive of adverse ND outcome had the most severe form of cerebral palsy. In this cohort, cerebral MRI was found to be highly predictive of neurodevelopmental outcome.

Dexmedetomidine Pharmacokinetics in Neonates with Hypoxic-Ischemic Encephalopathy Receiving Hypothermia

Dexmedetomidine is a promising sedative and analgesic for newborns with hypoxic-ischemic encephalopathy (HIE) undergoing therapeutic hypothermia (TH). Pharmacokinetics and safety of dexmedetomidine were evaluated in a phase I, single-center, open-label study to inform future trial strategies. We recruited 7 neonates ≥36 weeks' gestational age diagnosed with moderate-to-severe HIE, who received a continuous dexmedetomidine infusion during TH and the 6 h rewarming period. Time course of plasma dexmedetomidine concentration was characterized by serial blood sampling during and after the 64.8 ± 6.9 hours of infusion. Noncompartmental analysis yielded descriptive pharmacokinetic estimates: plasma clearance of 0.760 ± 0.155 L/h/kg, steady-state distribution volume of 5.22 ± 2.62 L/kg, and mean residence time of 6.84 ± 3.20 h. Naive pooled and population analyses according to a one-compartment model provided similar estimates of clearance and distribution volume. Overall, clearance was either comparable or lower, distribution volume was larger, and mean residence time or elimination half-life was longer in cooled newborns with HIE compared to corresponding estimates previously reported for uncooled (normothermic) newborns without HIE at comparable gestational and postmenstrual ages. As a result, plasma concentrations in cooled newborns with HIE rose more slowly in the initial hours of infusion compared to predicted concentration-time profiles based on reported pharmacokinetic parameters in normothermic newborns without HIE, while similar steady-state levels were achieved. No acute adverse events were associated with dexmedetomidine treatment. While dexmedetomidine appeared safe for neonates with HIE during TH at infusion doses up to 0.4 μg/kg/h, a loading dose strategy may be needed to overcome the initial lag in rise of plasma dexmedetomidine concentration.

Therapeutic hypothermia and N-PASS; results from implementation in a level 3 NICU

BACKGROUND

Neonates that have been subjected to perinatal asphyxia and fulfill criteria for therapeutic hypothermia are cooled to 33.5 °C for 72 h. There is no consensus regarding sedation and analgesic use during hypothermia, but there is evidence supporting the importance of pain relief and adequate sedation. There is a need for assessment of the neonates need for pain relief and sedation, and for adjustments of medication to ensure adequate treatment. There are many different scoring tools available. We found the N-PASS (Neonatal Pain, Agitation and Sedation Scale) scoring tool to be the most suitable for this patient group as it assesses both pain and sedation.

METHODS

We translated the scoring tool according to guidelines published by Wilder et al., and scored neonates treated with therapeutic hypothermia. Sedation and analgesia were adjusted according to scoring results. At the end of the study a questionnaire was filled out by the nurses in charge of this group of patients.

RESULTS

Both pain and sedation scores did not reach the desired levels until day 3. The nurses reported a high level of satisfaction (79.7% were extremely of very satisfied), and 96.7% of the nurses found the neonates to be better pain relieved after the initiation of the study.

CONCLUSION

The implementation of the N-PASS scoring tool in our unit has been successful, and has led to better pain relief and sedation than before the implementation.

WITHDRAWN: In clinical practice, cerebral MRI in newborns is highly predictive of neurodevelopmental outcome after therapeutic hypothermia

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Hypothermia and nutrient deprivation alter viability of human adipose-derived mesenchymal stem cells

PURPOSE

Adipose-derived mesenchymal stem cells (MSCs) are attractive biological agents in regenerative medicine. To optimize cell therapies, it is necessary to determine the most effective delivery method for MSCs. Therefore, we evaluated the biological properties of MSCs after exposure to various temperatures to define optimal storage conditions prior to therapeutic delivery of MSCs.

DESIGN

Prospective observational study.

METHODS AND MATERIALS

Adherent and non-adherent MSCs were incubated at multiple temperatures (i.e., 4, 23 and 37 °C) in Lactated Ringers (LR) solution lacking essential cell growth ingredients, or in culture media which is optimized for cell growth. Cells were assessed either after the temperature changes (4 h) or after recovery (24 h). Metabolic activity of MSCs, cell number and expression of representative mRNA biomarkers were evaluated to assess the biological effects of temperature. We monitored changes in mRNAs expression related to cytoprotective- or stress-related responses (e.g., FOS, JUN, ATF1, ATF4, EGR1, EGR2, MYC), proliferation (e.g., HIST2H4, CCNB2), and extracellular matrix production (ECM; e.g., COL3A1, COL1A1) by quantitative real time reverse-transcriptase polymerase chain reaction (RT-qPCR) analysis.

RESULTS

Our study demonstrates that storing MSCs in Lactated Ringers (LR) solution for 4 h decreases cell number and metabolic activity. The number of viable MSCs decreased significantly when cultured at physiological temperature (37 °C) and severe hypothermia (4 °C), while cells grown at ambient temperature (23 °C) exhibited the least detrimental effects. There were no appreciable biological differences in mRNA markers for proliferation or ECM deposition at any of the temperatures. However, biomarkers related to cytoprotective- or stress-responses were selectively elevated depending on temperature or media type (i.e., LR versus standard media).

CONCLUSION

The biological impact of nutrient-free media and temperature changes after 4 h exposure persists after a 24 h recovery period. Hence, storage temperature and media conditions should be optimized to improve effective dosing of MSCs.

RvD1binding with FPR2 attenuates inflammation via Rac1/NOX2 pathway after neonatal hypoxic-ischemic injury in rats

Neuroinflammation plays a crucial role in the pathological development after neonatal hypoxia-ischemia (HI). Resolvin D1 (RvD1), an agonist of formyl peptide receptor 2 (FPR2), has been shown to exert anti-inflammatory effects in many diseases. The objective of this study was to explore the protective role of RvD1 through reducing inflammation after HI and to study the contribution of Ras-related C3 botulinum toxin substrate 1 (Rac1)/nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2) pathways in RvD1-mediated protection. Rat pups (10-day old) were subjected to HI or sham surgery. RvD1 was administrated by intraperitoneal injection 1 h after HI. FPR2 small interfering ribonucleic acid (siRNA) and Rac1 activation CRISPR were administered prior to RvD1 treatment to elucidate the possible mechanisms. Time course expression of FPR2 by Western blot and RvD1 by ELISA were conducted at 6 h, 12 h, 24 h, 48 h and 72 h post HI. Infarction area, short-term neurological deficits, immunofluorescent staining and Western blot were conducted at 24 h post HI. Long-term neurological behaviors were evaluated at 4 weeks post HI. Endogenous expression levels of RvD1 decreased in time dependent manner while the expression of FPR2 increased after HI, peaking at 24 h post HI. Activation of FPR2, with RvD1, reduced percent infarction area, and alleviated short- and long-term neurological deficits. Administration of RvD1 attenuated inflammation after HI, while, either inhibition of FPR2 with siRNA or activation of Rac1 with CRISPR reversed those effects. Our results showed that RvD1 attenuated neuroinflammation through FPR2, which then interacted with Rac1/NOX2 signaling pathway, thereby reducing infarction area and alleviating neurological deficits after HI in neonatal rat pups. RvD1 may be a potential therapeutic approach to reduce inflammation after HI.

Quercetin attenuates hypoxia-ischemia induced brain injury in neonatal rats by inhibiting TLR4/NF-κB signaling pathway

Neonatal hypoxic ischemia (HI) is a kind of brain damage that occurs when an infant's brain does not receive enough oxygen and blood. The unrepairable damage leads to newborn death and short/long term brain dysfunctions. Due to the complicated causes and the variety of brain damages, there is no definitive treatment of neonatal HI. In this study, we set up a HI injury model of newborn rat and administrated Quercetin (Que) to treat rat pups before and after HI injury. We performed immunohistochemistry, quantitative PCR and immunoblot experiments to examine whether Que. has a role in attenuating brain injury after HI. We found that Que. treatment could clearly attenuate cortical cell apoptosis, as well as suppress apoptosis marker Bax, and activate anti-apoptosis marker Bcl-2. Moreover, Que. treatment decreased the number of cortical cells microgliosis and astrogliosis induced by HI injury. Furthermore, Que. treatment decreased cortical inflammation. Finally, it is suggested that Que. played a neuroprotective function on HI brain injury via inhibiting the TLR4/NF-κB signaling pathway. From these results, we conclude that Que. treatment may be a used as a therapeutic drug to prevent and decrease the newborn brain damage caused by HI.

Melatonin as a master regulator of cell death and inflammation: molecular mechanisms and clinical implications for newborn care

Melatonin, more commonly known as the sleep hormone, is mainly secreted by the pineal gland in dark conditions and regulates the circadian rhythm of the organism. Its intrinsic properties, including high cell permeability, the ability to easily cross both the blood–brain and placenta barriers, and its role as an endogenous reservoir of free radical scavengers (with indirect extra activities), confer it beneficial uses as an adjuvant in the biomedical field. Melatonin can exert its effects by acting through specific cellular receptors on the plasma membrane, similar to other hormones, or through receptor-independent mechanisms that involve complex molecular cross talk with other players. There is increasing evidence regarding the extraordinary beneficial effects of melatonin, also via exogenous administration. Here, we summarize molecular pathways in which melatonin is considered a master regulator, with attention to cell death and inflammation mechanisms from basic, translational and clinical points of view in the context of newborn care.

Increased expression of cannabinoid CB2 and serotonin 5-HT1A heteroreceptor complexes in a model of newborn hypoxic-ischemic brain damage

Preclinical work shows cannabidiol as a promising drug to manage neonatal hypoxic-ischemic brain damage (NHIBD). The molecular mechanism is not well defined but the beneficial effects of this phytocannabinoid are blocked by antagonists of both cannabinoid CB₂ (CB₂R) and serotonin 5-HT_1A (5-HT1AR) receptors that, in addition, may form heteromers in a heterologous expression system. Using bioluminescence energy transfer, we have shown a direct interaction of the two receptors that leads to a particular signaling in a heterologous system. A property attributed to the heteromer, namely cross-antagonism, was found in primary cultures of neurons thus indicating the occurrence of the receptor heteromer in the CNS. Oxygen-glucose deprivation to neurons led to an increase of CB₂R-mediated signaling and an upregulation of CB₂-5-HT_1A heteroreceptor complex expression. In situ proximity ligation assays in brain cortical sections were performed to compare the expression of CB₂-5-HT_1A complexes in rat E20 fetuses and at different postnatal days. The expression, which is elevated in fetus and shortly after birth, was sharply reduced at later ages (even at P7). The expression of heteromer receptors was more marked in a model of NHIBD and, remarkably, the drop in expression was significantly delayed with respect to controls. These results indicate that CB₂-5-HT_1A heteroreceptor complex may be considered as a target in the therapy of the NHIBD. This article is part of the Special Issue entitled 'Receptor heteromers and their allosteric receptor-receptor interactions'.

Combined application of hypothermia and medical gases in cerebrovascular diseases

Cerebrovascular diseases have a heavy burden on society and the family. At present, in the treatment of cerebrovascular diseases, the recognized effective treatment method is a thrombolytic therapy after cerebral infarction, but limited to the time window problem, many patients cannot benefit. Other treatments for cerebrovascular disease are still in the exploration stage. The study found that medical gas and hypothermia have brain protection effects. Further research found that when the two are used in combination, the therapeutic effect has a superimposed effect. This article reviews the current research progress of hypothermia therapy combined with medical gas therapy for cerebrovascular disease.

Combination therapy with erythropoietin, magnesium sulfate and hypothermia for hypoxic-ischemic encephalopathy: an open-label pilot study to assess the safety and feasibility

BACKGROUND

Although therapeutic hypothermia improves the outcome of neonatal hypoxic-ischemic encephalopathy (HIE), its efficacy is still limited. This preliminary study evaluates the safety and feasibility of the combination therapy with erythropoietin (Epo), magnesium sulfate and hypothermia in neonates with HIE.

METHODS

A combination therapy with Epo (300 U/kg every other day for 2 weeks), magnesium sulfate (250 mg/kg for 3 days) and hypothermia was started within 6 h of birth in neonates who met the institutional criteria for hypothermia therapy. All patients received continuous infusion of dopamine. Vital signs and adverse events were recorded during the therapy. Short-term and long-term developmental outcomes were also evaluated.

RESULTS

Nine patients were included in the study. The mean age at first intervention was 3.9 h (SD, 0.5). Death, serious adverse events or changes in vital signs likely due to intervention were not observed during hospital care. All nine patients completed the therapy. At the time of hospital discharge, eight patients had established oral feeding and did not require ventilation support. Two patients had abnormal MRI findings. At 18 months of age, eight patients received a follow-up evaluation, and three of them showed signs of severe neurodevelopmental disability.

CONCLUSION

The combination therapy with 300 U/kg Epo every other day for 2 weeks, 250 mg/kg magnesium sulphate for 3 days and therapeutic hypothermia is feasible in newborn patients with HIE.

TRIAL REGISTRATION

ISRCTN33604417 retrospectively registered on 14 September 2018.

Exogenous Neural Precursor Cell Transplantation Results in Structural and Functional Recovery in a Hypoxic-Ischemic Hemiplegic Mouse Model

Cerebral palsy (CP) is a common pediatric neurodevelopmental disorder, frequently resulting in motor and developmental deficits and often accompanied by cognitive impairments. A regular pathobiological hallmark of CP is oligodendrocyte maturation impairment resulting in white matter (WM) injury and reduced axonal myelination. Regeneration therapies based on cell replacement are currently limited, but neural precursor cells (NPCs), as cellular support for myelination, represent a promising regeneration strategy to treat CP, although the transplantation parameters (e.g., timing, dosage, mechanism) remain to be determined. We optimized a hemiplegic mouse model of neonatal hypoxia-ischemia that mirrors the pathobiological hallmarks of CP and transplanted NPCs into the corpus callosum (CC), a major white matter structure impacted in CP patients. The NPCs survived, engrafted, and differentiated morphologically in male and female mice. Histology and MRI showed repair of lesioned structures. Furthermore, electrophysiology revealed functional myelination of the CC (e.g., restoration of conduction velocity), while cylinder and CatWalk tests demonstrated motor recovery of the affected forelimb. Endogenous oligodendrocytes, recruited in the CC following transplantation of exogenous NPCs, are the principal actors in this recovery process. The lack of differentiation of the transplanted NPCs is consistent with enhanced recovery due to an indirect mechanism, such as a trophic and/or “bio-bridge” support mediated by endogenous oligodendrocytes. Our work establishes that transplantation of NPCs represents a viable therapeutic strategy for CP treatment, and that the enhanced recovery is mediated by endogenous oligodendrocytes. This will further our understanding and contribute to the improvement of cellular therapeutic strategies.

Perinatal hypoxic-ischemic brain injury in large animal models: Relevance to human neonatal encephalopathy

Perinatal hypoxia-ischemia resulting in death or lifelong disabilities remains a major clinical disorder. Neonatal models of hypoxia-ischemia in rodents have enhanced our understanding of cellular mechanisms of neural injury in developing brain, but have limitations in simulating the range, accuracy, and physiology of clinical hypoxia-ischemia and the relevant systems neuropathology that contribute to the human brain injury pattern. Large animal models of perinatal hypoxia-ischemia, such as partial or complete asphyxia at the time of delivery of fetal monkeys, umbilical cord occlusion and cerebral hypoperfusion at different stages of gestation in fetal sheep, and severe hypoxia and hypoperfusion in newborn piglets, have largely overcome these limitations. In monkey, complete asphyxia produces preferential injury to cerebellum and primary sensory nuclei in brainstem and thalamus, whereas partial asphyxia produces preferential injury to somatosensory and motor cortex, basal ganglia, and thalamus. Mid-gestational fetal sheep provide a valuable model for studying vulnerability of progenitor oligodendrocytes. Hypoxia followed by asphyxia in newborn piglets replicates the systems injury seen in term newborns. Efficacy of post-insult hypothermia in animal models led to the success of clinical trials in term human neonates. Large animal models are now being used to explore adjunct therapy to augment hypothermic neuroprotection.

Melatonin as a Hormone: New Physiological and Clinical Insights

Melatonin is a ubiquitous molecule present in almost every live being from bacteria to humans. In vertebrates, besides being produced in peripheral tissues and acting as an autocrine and paracrine signal, melatonin is centrally synthetized by a neuroendocrine organ, the pineal gland. Independently of the considered species, pineal hormone melatonin is always produced during the night and its production and secretory episode duration are directly dependent on the length of the night. As its production is tightly linked to the light/dark cycle, melatonin main hormonal systemic integrative action is to coordinate behavioral and physiological adaptations to the environmental geophysical day and season. The circadian signal is dependent on its daily production regularity, on the contrast between day and night concentrations, and on specially developed ways of action. During its daily secretory episode, melatonin coordinates the night adaptive physiology through immediate effects and primes the day adaptive responses through prospective effects that will only appear at daytime, when melatonin is absent. Similarly, the annual history of the daily melatonin secretory episode duration primes the central nervous/endocrine system to the seasons to come. Remarkably, maternal melatonin programs the fetuses' behavior and physiology to cope with the environmental light/dark cycle and season after birth. These unique ways of action turn melatonin into a biological time-domain-acting molecule. The present review focuses on the above considerations, proposes a putative classification of clinical melatonin dysfunctions, and discusses general guidelines to the therapeutic use of melatonin.

Neuroprotection by cannabidiol and hypothermia in a piglet model of newborn hypoxic-ischemic brain damage

OBJECTIVE

Hypothermia, the gold standard after a hypoxic-ischemic insult, is not beneficial in all treated newborns. Cannabidiol is neuroprotective in animal models of newborn hypoxic-ischemic encephalopathy. This study compared the relative efficacies of cannabidiol and hypothermia in newborn hypoxic-ischemic piglets and assessed whether addition of cannabidiol augments hypothermic neuroprotection.

METHODS

One day-old HI (carotid clamp and FiO₂ 10% for 20 min) piglets were randomized to vehicle or cannabidiol 1 mg/kg i.v. u.i.d. for three doses after being submitted to normothermia or 48 h-long hypothermia with a subsequent rewarming period of 6 h. Non-manipulated piglets (naïve) served as controls. Hemodynamic or respiratory parameters as well as brain activity (aEEG amplitude) were monitored throughout the experiment. Following termination, brains were obtained for histological (TUNEL staining, apoptosis; immunohistochemistry for Iba-1, microglia), biochemical (protein carbonylation, oxidative stress; and TNFα concentration, neuroinflammation) or proton magnetic resonance spectroscopy (Lac/NAA: metabolic derangement; Glu/NAA: excitotoxicity).

RESULTS

HI led to sustained depressed brain activity and increased microglial activation, which was significantly improved by cannabidiol alone or with hypothermia but not by hypothermia alone. Hypoxic-ischemic-induced increases in Lac/NAA, Glu/NAA, TNFα or apoptosis were not reversed by either hypothermia or cannabidiol alone, but combination of the therapies did. No treatment modified the effects of HI on oxidative stress or astroglial activation. Cannabidiol treatment was well tolerated.

CONCLUSIONS

cannabidiol administration after hypoxia-ischemia in piglets offers some neuroprotective effects but the combination of cannabidiol and hypothermia shows some additive effect leading to more complete neuroprotection than cannabidiol or hypothermia alone.

The complex aetiology of cerebral palsy

Cerebral palsy (CP) is the most prevalent, severe and costly motor disability of childhood. Consequently, CP is a public health priority for prevention, but its aetiology has proved complex. In this Review, we summarize the evidence for a decline in the birth prevalence of CP in some high-income nations, describe the epidemiological evidence for risk factors, such as preterm delivery and fetal growth restriction, genetics, pregnancy infection and other exposures, and discuss the success achieved so far in prevention through the use of magnesium sulfate in preterm labour and therapeutic hypothermia for birth-asphyxiated infants. We also consider the complexities of disentangling prenatal and perinatal influences, and of establishing subtypes of the disorder, with a view to accelerating the translation of evidence into the development of strategies for the prevention of CP.

Dexmedetomidine for Sedation of Neonates with HIE Undergoing Therapeutic Hypothermia: A Single-Center Experience

Hypoxic-ischemic encephalopathy (HIE) is a significant cause of morbidity and mortality in neonates. Therapeutic hypothermia reduces the risk of death or disability. Providing optimal sedation while neonates are undergoing therapeutic hypothermia is likely beneficial but may present therapeutic challenges. There are limited data describing the use of dexmedetomidine for sedation in patients undergoing therapeutic hypothermia. The objective of this study is to evaluate the efficacy and short-term safety of dexmedetomidine infusion for sedation in term neonates undergoing therapeutic hypothermia for HIE.

Peripartum events associated with severe neurologic morbidity and mortality among acidemic neonates

PURPOSE

To identify peripartum events that may predict the development of short-term neurologic morbidity and mortality among acidemic neonates.

METHODS

Retrospective case-control study conducted at a single-teaching hospital on data from January 2010 to December 2015. The study cohort group included all acidemic neonates (cord artery pH ≤ 7.1) born at ≥ 34 weeks. Primary outcome was a composite including any of the following: neonatal encephalopathy, convulsions, intra-ventricular hemorrhage, or neonatal death. The study cohort was divided to the cases group, i.e., acidemic neonates who had any component of the primary outcome, and a control group, i.e., acidemic neonates who did not experience any component of the primary outcome.

RESULTS

Of all 24,311 neonates born ≥ 34 weeks during the study period, 568 (2.3%) had a cord artery pH ≤ 7.1 and composed the cohort study group. Twenty-one (3.7%) neonates composed the cases group. Multivariate logistic regression analysis revealed that cases were significantly more likely to have experienced placental abruption (OR 18.78; 95% CI 5.57-63.26), born ≤ 2500 g (OR 13.58; 95% CI 3.70-49.90), have meconium (OR 3.80; 95% CI 1.20-11.98) and cord entanglement (OR 5.99; 95% CI 1.79-20.06). The probability for developing the composite outcome rose from 3.7% with isolated acidemia to 97% among neonates who had all these peripartum events combined with intrapartum fetal heart rate tracing category 2 or 3.

CONCLUSION

Neonatal acidemia carries a favorable outcome in the vast majority of cases. In association with particular antenatal and intrapartum events, the short-term outcome may be unfavorable.

Long-Term Recovery After Endothelial Colony-Forming Cells or Human Umbilical Cord Blood Cells Administration in a Rat Model of Neonatal Hypoxic-Ischemic Encephalopathy

Neonatal hypoxic‐ischemic encephalopathy (NHIE) is a dramatic perinatal complication, associated with poor neurological prognosis despite neuroprotection by therapeutic hypothermia, in the absence of an available curative therapy. We evaluated and compared ready‐to‐use human umbilical cord blood cells (HUCBC) and bankable but allogeneic endothelial progenitors (ECFC) as cell therapy candidate for NHIE. We compared benefits of HUCBC and ECFC transplantation 48 hours after injury in male rat NHIE model, based on the Rice‐Vannucci approach. Based on behavioral tests, immune‐histological assessment and metabolic imaging of brain perfusion using single photon emission computed tomography (SPECT), HUCBC, or ECFC administration provided equally early and sustained functional benefits, up to 8 weeks after injury. These results were associated with total normalization of injured hemisphere cerebral blood flow assessed by SPECT/CT imaging. In conclusion, even if ECFC represent an efficient candidate, HUCBC autologous criteria and easier availability make them the ideal candidate for hypoxic‐ischemic cell therapy. Stem Cells Translational Medicine2017;6:1987–1996

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.