Therapeutic Hypothermia for Hypoxic-Ischemic Brain Injury Is More Effective in Newborn Infants than in Older Patients: Review and Hypotheses

Copper supplementation alleviates hypoxia‑induced ferroptosis and oxidative stress in neuronal cells

Hypoxic ischemia is the primary cause of brain damage in newborns. Notably, copper supplementation has potential benefits in ischemic brain damage; however, the precise mechanisms underlying this protective effect remain unclear. In the present study, a hypoxic HT22 cell model was developed to examine the mechanism by which copper mitigates hypoxia‑induced oxidative stress. Cell viability was assessed using the Cell Counting Kit‑8 assay, mitochondrial structure was examined with a transmission electron microscope, intracellular ferrous ions and lipid reactive oxygen species levels in HT22 cells were measured using FerroOrange and BODIPY 581/591 C11 staining, copper content was determined using graphite furnace atomic absorption spectroscopy, and gene and protein expression were analyzed by reverse transcription‑quantitative PCR and western blotting. The present findings indicated that hypoxic exposure may lead to reduced cell viability, along with the upregulation of various markers associated with ferroptosis. Furthermore, hypoxia elevated the levels of reactive oxygen species, hydrogen peroxide and malondialdehyde, and decreased the activity of superoxide dismutase 1 (SOD1) in HT22 cells. In addition, the intracellular copper concentration exhibited a notable decrease, while supplementation with an appropriate dose of copper effectively shielded neurons from hypoxia‑induced oxidative stress and ferroptosis, and elevated cell viability in hypoxia‑exposed HT22 cells through the copper chaperone for superoxide dismutase/SOD1/glutathione peroxidase 4 axis. In conclusion, the present study identified a novel function of copper in protecting neurons from oxidative stress and ferroptosis under hypoxic conditions, providing fresh insights into the therapeutic potential of copper in mitigating hypoxia‑induced neuronal injury.

Neuroprotection provided by hypothermia initiated with high transnasal flow with ambient air in a model of pediatric cardiac arrest

Clinical trials of hypothermia after pediatric cardiac arrest (CA) have not seen robust improvement in functional outcome, possibly because of the long delay in achieving target temperature. Previous work in infant piglets showed that high nasal airflow, which induces evaporative cooling in the nasal mucosa, reduced regional brain temperature uniformly in half the time needed to reduce body temperature. Here, we evaluated whether initiation of hypothermia with high transnasal airflow provides neuroprotection without adverse effects in the setting of asphyxic CA. Anesthetized piglets underwent sham-operated procedures (n = 7) or asphyxic CA with normothermic recovery (38.5°C; n = 9) or hypothermia initiated by surface cooling at 10 (n = 8) or 120 (n = 7) min or transnasal cooling initiated at 10 (n = 7) or 120 (n = 7) min after resuscitation. Hypothermia was sustained at 34°C with surface cooling until 20 h followed by 6 h of rewarming. At 4 days of recovery, significant neuronal loss occurred in putamen and sensorimotor cortex. Transnasal cooling initiated at 10 min significantly rescued the number of viable neurons in putamen, whereas levels in putamen in other hypothermic groups remained less than sham levels. In sensorimotor cortex, neuronal viability in the four hypothermic groups was not significantly different from the sham group. These results demonstrate that early initiation of high transnasal airflow in a pediatric CA model is effective in protecting vulnerable brain regions. Because of its simplicity, portability, and low cost, transnasal cooling potentially could be deployed in the field or emergency room for early initiation of brain cooling after pediatric CA.NEW & NOTEWORTHY The onset of therapeutic hypothermia after cardiac resuscitation is often delayed, leading to incomplete neuroprotection. In an infant swine model of asphyxic cardiac arrest, initiation of high transnasal airflow to maximize nasal evaporative cooling produced hypothermia sufficient to provide neuroprotection that was not inferior to body surface cooling. Because of its simplicity and portability, this technique may be of use in the field or emergency room for rapid brain cooling in pediatric cardiac arrest victims.

Advances in Therapies to Treat Neonatal Hypoxic-Ischemic Encephalopathy

Neonatal hypoxic-ischemic encephalopathy (HIE) is a condition that results in brain damage in newborns due to insufficient blood and oxygen supply during or after birth. HIE is a major cause of neurological disability and mortality in newborns, with over one million neonatal deaths occurring annually worldwide. The severity of brain injury and the outcome of HIE depend on several factors, including the cause of oxygen deprivation, brain maturity, regional blood flow, and maternal health conditions. HIE is classified into mild, moderate, and severe categories based on the extent of brain damage and resulting neurological issues. The pathophysiology of HIE involves different phases, including the primary phase, latent phase, secondary phase, and tertiary phase. The primary and secondary phases are characterized by episodes of energy and cell metabolism failures, increased cytotoxicity and apoptosis, and activated microglia and inflammation in the brain. A tertiary phase occurs if the brain injury persists, characterized by reduced neural plasticity and neuronal loss. Understanding the cellular and molecular aspects of the different phases of HIE is crucial for developing new interventions and therapeutics. This review aims to discuss the pathophysiology of HIE, therapeutic hypothermia (TH), the only approved therapy for HIE, ongoing developments of adjuvants for TH, and potential future drugs for HIE.