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Yang ZJ, Hopkins CD, Santos PT, Adams S, Kulikowicz E, Lee JK, Tandri H, Koehler RC. Neuroprotection provided by hypothermia initiated with high transnasal flow with ambient air in a model of pediatric cardiac arrest. Am J Physiol Regul Integr Comp Physiol 2024; 327:R304-R318. [PMID: 38860282 DOI: 10.1152/ajpregu.00078.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 05/28/2024] [Accepted: 06/05/2024] [Indexed: 06/12/2024]
Abstract
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.
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Affiliation(s)
- Zeng-Jin Yang
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland, United States
| | - C Danielle Hopkins
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland, United States
| | - Polan T Santos
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland, United States
| | - Shawn Adams
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland, United States
| | - Ewa Kulikowicz
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland, United States
| | - Jennifer K Lee
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland, United States
| | - Harikrishna Tandri
- Department of Medicine, Johns Hopkins University, Baltimore, Maryland, United States
| | - Raymond C Koehler
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland, United States
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2
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McDouall A, Zhou KQ, Davies A, Wassink G, Jones TLM, Bennet L, Gunn AJ, Davidson JO. Slow rewarming after hypothermia does not ameliorate white matter injury after hypoxia-ischemia in near-term fetal sheep. Pediatr Res 2024:10.1038/s41390-024-03332-y. [PMID: 39103629 DOI: 10.1038/s41390-024-03332-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 04/10/2024] [Accepted: 05/18/2024] [Indexed: 08/07/2024]
Abstract
BACKGROUND The optimal rate to rewarm infants after therapeutic hypothermia is unclear. In this study we examined whether slow rewarming after 72 h of hypothermia would attenuate white matter injury. METHODS Near-term fetal sheep received sham occlusion (n = 8) or cerebral ischemia for 30 min, followed by normothermia (n = 7) or hypothermia from 3-72 h, with either spontaneous fast rewarming (n = 8) within 1 h, or slow rewarming at ~0.5 °C/h (n = 8) over 10 h. Fetuses were euthanized 7 days later. RESULTS Ischemia was associated with loss of total and mature oligodendrocytes, reduced expression of myelin proteins and induction of microglia and astrocytes, compared with sham controls (P < 0.05). Both hypothermia protocols were associated with a significant increase in numbers of total and mature oligodendrocytes, area fraction of myelin proteins and reduced numbers of microglia and astrocytes, compared with ischemia-normothermia (P < 0.05). There was no difference in the number of oligodendrocytes, microglia or astrocytes or expression of myelin proteins between fast and slow rewarming after hypothermia. CONCLUSION The rate of rewarming after a clinically relevant duration of hypothermia had no apparent effect on white matter protection by hypothermia after cerebral ischemia in near-term fetal sheep. IMPACT Persistent white matter injury is a major contributor to long-term disability after neonatal encephalopathy despite treatment with therapeutic hypothermia. The optimal rate to rewarm infants after therapeutic hypothermia is unclear; current protocols were developed on a precautionary basis. We now show that slow rewarming at 0.5 °C/h did not improve histological white matter injury compared with rapid spontaneous rewarming after a clinically established duration of hypothermia in near-term fetal sheep.
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Affiliation(s)
- Alice McDouall
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Kelly Q Zhou
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Anthony Davies
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Guido Wassink
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Timothy L M Jones
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Joanne O Davidson
- Department of Physiology, The University of Auckland, Auckland, New Zealand.
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3
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Gundersen JK, Chakkarapani E, Menassa DA, Walløe L, Thoresen M. The effects of anaesthesia on cell death in a porcine model of neonatal hypoxic-ischaemic brain injury. BJA OPEN 2024; 10:100283. [PMID: 38741692 PMCID: PMC11089311 DOI: 10.1016/j.bjao.2024.100283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Accepted: 03/30/2024] [Indexed: 05/16/2024]
Abstract
Background Hypothermia is neuroprotective after neonatal hypoxic-ischaemic brain injury. However, systemic cooling to hypothermic temperatures is a stressor and may reduce neuroprotection in awake pigs. We compared two experiments of global hypoxic-ischaemic injury in newborn pigs, in which one group received propofol-remifentanil and the other remained awake during post-insult hypothermia treatment. Methods In both studies, newborn pigs were anaesthetised using halothane during a 45-min global hypoxic-ischaemic insult induced by reducing Fio2 and graded hypotension until a low-voltage <7 μV electroencephalogram was achieved. On reoxygenation, the pigs were randomly allocated to receive 24 h of normothermia or hypothermia. In the first study (n=18) anaesthesia was discontinued and the pigs' tracheas were extubated. In the second study (n=14) anaesthesia was continued using propofol and remifentanil. Brain injury was assessed after 72 h by classical global histopathology, Purkinje cell count, and apoptotic cell counts in the hippocampus and cerebellum. Results Global injury was nearly 10-fold greater in the awake group compared with the anaesthetised group (P=0.021). Hypothermia was neuroprotective in the anaesthetised pigs but not the awake pigs. In the hippocampus, the density of cleaved caspase-3-positive cells was increased in awake compared with anaesthetised pigs in normothermia. In the cerebellum, Purkinje cell density was reduced in the awake pigs irrespective of treatment, and the number of cleaved caspase-3-positive Purkinje cells was greatly increased in hypothermic awake pigs. We detected no difference in cleaved caspase-3 in the granular cell layer or microglial reactivity across the groups. Conclusions Our study provides novel insights into the significance of anaesthesia/sedation during hypothermia for achieving optimal neuroprotection.
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Affiliation(s)
- Julia K. Gundersen
- Department of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
- Department of Neurology, Akershus University Hospital, Lørenskog, Norway
| | - Ela Chakkarapani
- Translational Health Sciences, St. Michael's Hospital, Bristol Medical School, University of Bristol, Bristol, UK
| | - David A. Menassa
- Department of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
- Department of Neuropathology and The Queen's College, University of Oxford, Oxford, UK
- Department of Women's & Children's Health, Karolinska Institutet, Solna, Sweden
| | - Lars Walløe
- Department of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Marianne Thoresen
- Department of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
- Translational Health Sciences, St. Michael's Hospital, Bristol Medical School, University of Bristol, Bristol, UK
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4
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Malhotra A, Thebaud B, Paton MCB, Fleiss B, Papagianis P, Baker E, Bennet L, Yawno T, Elwood N, Campbell B, Chand K, Zhou L, Penny T, Nguyen T, Pepe S, Gunn AJ, McDonald CA. Advances in neonatal cell therapies: Proceedings of the First Neonatal Cell Therapies Symposium (2022). Pediatr Res 2023; 94:1631-1638. [PMID: 37380752 PMCID: PMC10624618 DOI: 10.1038/s41390-023-02707-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 05/08/2023] [Accepted: 06/08/2023] [Indexed: 06/30/2023]
Abstract
Despite considerable advances, there is a need to improve the outcomes of newborn infants, especially related to prematurity, encephalopathy and other conditions. In principle, cell therapies have the potential to protect, repair, or sometimes regenerate vital tissues; and improve or sustain organ function. In this review, we present highlights from the First Neonatal Cell Therapies Symposium (2022). Cells tested in preclinical and clinical studies include mesenchymal stromal cells from various sources, umbilical cord blood and cord tissue derived cells, and placental tissue and membrane derived cells. Overall, most preclinical studies suggest potential for benefit, but many of the cells tested were not adequately defined, and the optimal cell type, timing, frequency, cell dose or the most effective protocols for the targeted conditions is not known. There is as yet no clinical evidence for benefit, but several early phase clinical trials are now assessing safety in newborn babies. We discuss parental perspectives on their involvement in these trials, and lessons learnt from previous translational work of promising neonatal therapies. Finally, we make a call to the many research groups around the world working in this exciting yet complex field, to work together to make substantial and timely progress to address the knowledge gaps and move the field forward. IMPACT: Survival of preterm and sick newborn infants is improving, but they continue to be at high risk of many systemic and organ-specific complications. Cell therapies show promising results in preclinical models of various neonatal conditions and early phase clinical trials have been completed or underway. Progress on the potential utility of cell therapies for neonatal conditions, parental perspectives and translational aspects are discussed in this paper.
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Affiliation(s)
- Atul Malhotra
- Department of Paediatrics, Monash University, Melbourne, VIC, Australia.
- Monash Newborn, Monash Children's Hospital, Melbourne, VIC, Australia.
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia.
| | - Bernard Thebaud
- Regenerative Medicine Program, The Ottawa Hospital Research Institute (OHRI), Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
- Neonatology, Department of Pediatrics, Children's Hospital of Eastern Ontario (CHEO) and CHEO Research Institute, Ottawa, ON, Canada
| | - Madison C B Paton
- Cerebral Palsy Alliance Research Institute; Speciality of Child and Adolescent Health, Sydney Medical School, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | | | - Paris Papagianis
- Department of Pharmacology, Monash University, Melbourne, VIC, Australia
| | - Elizabeth Baker
- Royal Women's Hospital, Melbourne, VIC, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia
| | - Laura Bennet
- Departments of Physiology and Paediatrics, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Tamara Yawno
- Department of Paediatrics, Monash University, Melbourne, VIC, Australia
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
| | - Ngaire Elwood
- Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia
- Murdoch Children's Research Institute, Melbourne, VIC, Australia
| | - Belinda Campbell
- Monash Newborn, Monash Children's Hospital, Melbourne, VIC, Australia
| | - Kirat Chand
- Perinatal Research Centre, University of Queensland, Brisbane, QLD, Australia
| | - Lindsay Zhou
- Department of Paediatrics, Monash University, Melbourne, VIC, Australia
- Monash Newborn, Monash Children's Hospital, Melbourne, VIC, Australia
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
| | - Tayla Penny
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - Timothy Nguyen
- Department of Paediatrics, Monash University, Melbourne, VIC, Australia
| | - Salvatore Pepe
- Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia
- Murdoch Children's Research Institute, Melbourne, VIC, Australia
| | - Alistair J Gunn
- Departments of Physiology and Paediatrics, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Courtney A McDonald
- The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
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5
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Korf JM, McCullough LD, Caretti V. A narrative review on treatment strategies for neonatal hypoxic ischemic encephalopathy. Transl Pediatr 2023; 12:1552-1571. [PMID: 37692539 PMCID: PMC10485647 DOI: 10.21037/tp-23-253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 08/08/2023] [Indexed: 09/12/2023] Open
Abstract
Background and Objective Hypoxic-ischemic encephalopathy (HIE) is a leading cause of death and disability worldwide. Therapeutic hypothermia (TH) represents a significant achievement in the translation of scientific research to clinical application, but it is currently the only neuroprotective treatment for HIE. This review aims to revisit the use of TH for HIE and its longitudinal impact on patient outcomes to readers new to the field of HIE. We discuss how emerging therapies address the broader pathophysiology of injury progression in the neonatal brain days to years after HIE. Methods We included full articles and book chapters published in English on PubMed with references to "hypoxic ischemic encephalopathy", "birth asphyxia", "therapeutic hypothermia", or "neonatal encephalopathy". We limited our review to outcomes on term infants and to new therapeutics that are in the second phase of clinical trials. Key Content and Findings Despite the use of TH for HIE, mortality remains high. Analysis of longitudinal studies reveals a high incidence of ongoing disability even with the implementation of TH. New therapeutics addressing the secondary phase and the less understood tertiary phase of brain injury are in clinical trials as adjunctive treatments to TH to support additional neurological repair and regeneration. Conclusions TH successfully improves outcomes after HIE, and it continues to be optimized. Larger studies are needed to understand its use in mild cases of HIE and if certain factors, such as sex, affect long term outcomes. TH primarily acts in the initial phases of injury, while new pharmaceutical therapies target additional injury pathways into the tertiary phases of injury. This may allow for more effective approaches to treatment and improvement of long-term functional outcomes after HIE.
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Affiliation(s)
- Janelle M. Korf
- Department of Neurology, University of Texas McGovern Medical School, Houston, TX, USA
| | - Louise D. McCullough
- Department of Neurology, University of Texas McGovern Medical School, Houston, TX, USA
| | - Viola Caretti
- Department of Neurology, University of Texas McGovern Medical School, Houston, TX, USA
- Department of Pediatrics, Section of Pediatric Neurology and Developmental Neuroscience, Baylor College of Medicine, Houston, TX, USA
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6
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Elmer J, Callaway CW. Temperature control after cardiac arrest. Resuscitation 2023; 189:109882. [PMID: 37355091 PMCID: PMC10530429 DOI: 10.1016/j.resuscitation.2023.109882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 06/13/2023] [Accepted: 06/14/2023] [Indexed: 06/26/2023]
Abstract
Managing temperature is an important part of post-cardiac arrest care. Fever or hyperthermia during the first few days after cardiac arrest is associated with worse outcomes in many studies. Clinical data have not determined any target temperature or duration of temperature management that clearly improves patient outcomes. Current guidelines and recent reviews recommend controlling temperature to prevent hyperthermia. Higher temperatures can lead to secondary brain injury by increasing seizures, brain edema and metabolic demand. Some data suggest that targeting temperature below normal could benefit select patients where this pathology is common. Clinical temperature management should address the physiology of heat balance. Core temperature reflects the heat content of the head and torso, and changes in core temperature result from changes in the balance of heat production and heat loss. Clinical management of patients after cardiac arrest should include measurement of core temperature at accurate sites and monitoring signs of heat production including shivering. Multiple methods can increase or decrease heat loss, including external and internal devices. Heat loss can trigger compensatory reflexes that increase stress and metabolic demand. Therefore, any active temperature management should include specific pharmacotherapy or other interventions to control thermogenesis, especially shivering. More research is required to determine whether individualized temperature management can improve outcomes.
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Affiliation(s)
- Jonathan Elmer
- Department of Emergency Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Clifton W Callaway
- Department of Emergency Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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7
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Yang P, Davidson JO, Zhou KQ, Wilson R, Wassink G, Prasad JD, Bennet L, Gunn AJ, Dean JM. Therapeutic Hypothermia Attenuates Cortical Interneuron Loss after Cerebral Ischemia in Near-Term Fetal Sheep. Int J Mol Sci 2023; 24:ijms24043706. [PMID: 36835117 PMCID: PMC9962824 DOI: 10.3390/ijms24043706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/26/2023] [Accepted: 02/07/2023] [Indexed: 02/16/2023] Open
Abstract
Therapeutic hypothermia significantly improves outcomes after neonatal hypoxic-ischemic (HI) encephalopathy but is only partially protective. There is evidence that cortical inhibitory interneuron circuits are particularly vulnerable to HI and that loss of interneurons may be an important contributor to long-term neurological dysfunction in these infants. In the present study, we examined the hypothesis that the duration of hypothermia has differential effects on interneuron survival after HI. Near-term fetal sheep received sham ischemia or cerebral ischemia for 30 min, followed by cerebral hypothermia from 3 h after ischemia end and continued up to 48 h, 72 h, or 120 h recovery. Sheep were euthanized after 7 days for histology. Hypothermia up to 48 h recovery resulted in moderate neuroprotection of glutamate decarboxylase (GAD)+ and parvalbumin+ interneurons but did not improve survival of calbindin+ cells. Hypothermia up to 72 h recovery was associated with significantly increased survival of all three interneuron phenotypes compared with sham controls. By contrast, while hypothermia up to 120 h recovery did not further improve (or impair) GAD+ or parvalbumin+ neuronal survival compared with hypothermia up to 72 h, it was associated with decreased survival of calbindin+ interneurons. Finally, protection of parvalbumin+ and GAD+ interneurons, but not calbindin+ interneurons, with hypothermia was associated with improved recovery of electroencephalographic (EEG) power and frequency by day 7 after HI. The present study demonstrates differential effects of increasing the duration of hypothermia on interneuron survival after HI in near-term fetal sheep. These findings may contribute to the apparent preclinical and clinical lack of benefit of very prolonged hypothermia.
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Molloy EJ, El-Dib M, Juul SE, Benders M, Gonzalez F, Bearer C, Wu YW, Robertson NJ, Hurley T, Branagan A, Michael Cotten C, Tan S, Laptook A, Austin T, Mohammad K, Rogers E, Luyt K, Bonifacio S, Soul JS, Gunn AJ. Neuroprotective therapies in the NICU in term infants: present and future. Pediatr Res 2022:10.1038/s41390-022-02295-2. [PMID: 36195634 PMCID: PMC10070589 DOI: 10.1038/s41390-022-02295-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 08/09/2022] [Accepted: 08/18/2022] [Indexed: 01/13/2023]
Abstract
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.
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Affiliation(s)
- Eleanor J Molloy
- Paediatrics, Trinity College Dublin, Trinity Research in Childhood Centre (TRICC), Dublin, Ireland. .,Children's Hospital Ireland (CHI) at Tallaght, Dublin, Ireland. .,Neonatology, CHI at Crumlin, Dublin, Ireland. .,Neonatology, Coombe Women's and Infants University Hospital, Dublin, Ireland.
| | - Mohamed El-Dib
- Department of Pediatric Newborn Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | | | - Manon Benders
- Department of Neonatology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Fernando Gonzalez
- Department of Neurology, Division of Child Neurology, University of California San Francisco, San Francisco, CA, USA
| | - Cynthia Bearer
- Division of Neonatology, Department of Pediatrics, Rainbow Babies & Children's Hospital, Cleveland, OH, USA.,Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Yvonne W Wu
- Department of Neurology, University of California San Francisco, San Francisco, CA, USA
| | - Nicola J Robertson
- Institute for Women's Health, University College London, London, UK.,Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Tim Hurley
- Paediatrics, Trinity College Dublin, Trinity Research in Childhood Centre (TRICC), Dublin, Ireland.,Neonatology, Coombe Women's and Infants University Hospital, Dublin, Ireland
| | - Aoife Branagan
- Paediatrics, Trinity College Dublin, Trinity Research in Childhood Centre (TRICC), Dublin, Ireland.,Neonatology, Coombe Women's and Infants University Hospital, Dublin, Ireland
| | | | - Sidhartha Tan
- Pediatrics, Division of Neonatology, Children's Hospital of Michigan, Detroit, MI, USA.,Wayne State University School of Medicine, Detroit, MI, 12267, USA.,Pediatrics, Division of Neonatology, Central Michigan University, Mount Pleasant, MI, USA
| | - Abbot Laptook
- Department of Pediatrics, Women and Infants Hospital, Brown University, Providence, RI, USA
| | - Topun Austin
- Department of Paediatrics, University of Cambridge, Cambridge, UK
| | - Khorshid Mohammad
- Section of Neonatology, Department of Pediatrics, University of Calgary, Calgary, AB, Canada
| | - Elizabeth Rogers
- Department of Pediatrics, University of California, San Francisco Benioff Children's Hospital, San Francisco, CA, USA
| | - Karen Luyt
- Translational Health Sciences, University of Bristol, Bristol, UK.,Neonatology, University Hospitals Bristol and Weston NHS Foundation Trust, Bristol, UK
| | - Sonia Bonifacio
- Division of Neonatal and Developmental Medicine, Department of Pediatrics, Stanford University School of Medicine, 750 Welch Road, Suite 315, Palo Alto, CA, 94304, USA
| | - Janet S Soul
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Alistair J Gunn
- Departments of Physiology and Paediatrics, School of Medical Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand
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9
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Persistent cortical and white matter inflammation after therapeutic hypothermia for ischemia in near-term fetal sheep. J Neuroinflammation 2022; 19:139. [PMID: 35690757 PMCID: PMC9188214 DOI: 10.1186/s12974-022-02499-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 05/23/2022] [Indexed: 02/07/2023] Open
Abstract
Background Therapeutic hypothermia significantly improves outcomes after moderate–severe hypoxic-ischemic encephalopathy (HIE), but it is partially effective. Although hypothermia is consistently associated with reduced microgliosis, it is still unclear whether it normalizes microglial morphology and phenotype. Methods Near-term fetal sheep (n = 24) were randomized to sham control, ischemia-normothermia, or ischemia-hypothermia. Brain sections were immunohistochemically labeled to assess neurons, microglia and their interactions with neurons, astrocytes, myelination, and gitter cells (microglia with cytoplasmic lipid granules) 7 days after cerebral ischemia. Lesions were defined as areas with complete loss of cells. RNAscope® was used to assess microglial phenotype markers CD86 and CD206. Results Ischemia-normothermia was associated with severe loss of neurons and myelin (p < 0.05), with extensive lesions, astrogliosis and microgliosis with a high proportion of gitter cells (p < 0.05). Microglial wrapping of neurons was present in both the ischemia groups. Hypothermia improved neuronal survival, suppressed lesions, gitter cells and gliosis (p < 0.05), and attenuated the reduction of myelin area fraction. The “M1” marker CD86 and “M2” marker CD206 were upregulated after ischemia. Hypothermia partially suppressed CD86 in the cortex only (p < 0.05), but did not affect CD206. Conclusions Hypothermia prevented lesions after cerebral ischemia, but only partially suppressed microglial wrapping and M1 marker expression. These data support the hypothesis that persistent upregulation of injurious microglial activity may contribute to partial neuroprotection after hypothermia, and that immunomodulation after rewarming may be an important therapeutic target.
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10
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Luhmann HJ, Kanold PO, Molnár Z, Vanhatalo S. Early brain activity: Translations between bedside and laboratory. Prog Neurobiol 2022; 213:102268. [PMID: 35364141 PMCID: PMC9923767 DOI: 10.1016/j.pneurobio.2022.102268] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 03/01/2022] [Accepted: 03/25/2022] [Indexed: 01/29/2023]
Abstract
Neural activity is both a driver of brain development and a readout of developmental processes. Changes in neuronal activity are therefore both the cause and consequence of neurodevelopmental compromises. Here, we review the assessment of neuronal activities in both preclinical models and clinical situations. We focus on issues that require urgent translational research, the challenges and bottlenecks preventing translation of biomedical research into new clinical diagnostics or treatments, and possibilities to overcome these barriers. The key questions are (i) what can be measured in clinical settings versus animal experiments, (ii) how do measurements relate to particular stages of development, and (iii) how can we balance practical and ethical realities with methodological compromises in measurements and treatments.
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Affiliation(s)
- Heiko J. Luhmann
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, Mainz, Germany.,Correspondence:, , ,
| | - Patrick O. Kanold
- Department of Biomedical Engineering and Kavli Neuroscience Discovery Institute, Johns Hopkins University, School of Medicine, 720 Rutland Avenue / Miller 379, Baltimore, MD 21205, USA.,Correspondence:, , ,
| | - Zoltán Molnár
- Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Parks Road, Oxford OX1 3PT, UK.
| | - Sampsa Vanhatalo
- BABA Center, Departments of Physiology and Clinical Neurophysiology, Children's Hospital, Helsinki University Hospital, Helsinki, Finland.
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11
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Martinello KA, Meehan C, Avdic-Belltheus A, Lingam I, Mutshiya T, Yang Q, Akin MA, Price D, Sokolska M, Bainbridge A, Hristova M, Tachtsidis I, Tann CJ, Peebles D, Hagberg H, Wolfs TGAM, Klein N, Kramer BW, Fleiss B, Gressens P, Golay X, Robertson NJ. Hypothermia is not therapeutic in a neonatal piglet model of inflammation-sensitized hypoxia-ischemia. Pediatr Res 2022; 91:1416-1427. [PMID: 34050269 PMCID: PMC8160560 DOI: 10.1038/s41390-021-01584-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 04/20/2021] [Accepted: 05/10/2021] [Indexed: 02/04/2023]
Abstract
BACKGROUND Perinatal inflammation combined with hypoxia-ischemia (HI) exacerbates injury in the developing brain. Therapeutic hypothermia (HT) is standard care for neonatal encephalopathy; however, its benefit in inflammation-sensitized HI (IS-HI) is unknown. METHODS Twelve newborn piglets received a 2 µg/kg bolus and 1 µg/kg/h infusion over 52 h of Escherichia coli lipopolysaccharide (LPS). HI was induced 4 h after LPS bolus. After HI, piglets were randomized to HT (33.5 °C 1-25 h after HI, n = 6) or normothermia (NT, n = 6). Amplitude-integrated electroencephalogram (aEEG) was recorded and magnetic resonance spectroscopy (MRS) was acquired at 24 and 48 h. At 48 h, terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL)-positive brain cell death, microglial activation/proliferation, astrogliosis, and cleaved caspase-3 (CC3) were quantified. Hematology and plasma cytokines were serially measured. RESULTS Two HT piglets died. aEEG recovery, thalamic and white matter MRS lactate/N-acetylaspartate, and TUNEL-positive cell death were similar between groups. HT increased microglial activation in the caudate, but had no other effect on glial activation/proliferation. HT reduced CC3 overall. HT suppressed platelet count and attenuated leukocytosis. Cytokine profile was unchanged by HT. CONCLUSIONS We did not observe protection with HT in this piglet IS-HI model based on aEEG, MRS, and immunohistochemistry. Immunosuppressive effects of HT and countering neuroinflammation by LPS may contribute to the observed lack of HT efficacy. Other immunomodulatory strategies may be more effective in IS-HI. IMPACT Acute infection/inflammation is known to exacerbate perinatal brain injury and can worsen the outcomes in neonatal encephalopathy. Therapeutic HT is the current standard of care for all infants with NE, but the benefit in infants with coinfection/inflammation is unknown. In a piglet model of inflammation (LPS)-sensitized HI, we observed no evidence of neuroprotection with cooling for 24 h, based on our primary outcome measures: aEEG, MRS Lac/NAA, and histological brain cell death. Additional neuroprotective agents, with beneficial immunomodulatory effects, require exploration in IS-HI models.
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Affiliation(s)
- Kathryn A Martinello
- Institute for Women's Health, University College London, London, UK
- Robinson Research Institute, University of Adelaide, Adelaide, SA, Australia
| | | | | | - Ingran Lingam
- Institute for Women's Health, University College London, London, UK
| | - Tatenda Mutshiya
- Institute for Women's Health, University College London, London, UK
| | - Qin Yang
- Institute for Women's Health, University College London, London, UK
| | - Mustafa Ali Akin
- Department of Paediatrics, Ondokuz Mayıs University, Samsun, Turkey
| | - David Price
- Medical Physics and Biomedical Engineering, University College London NHS Foundation Trust, London, UK
| | - Magdalena Sokolska
- Medical Physics and Biomedical Engineering, University College London NHS Foundation Trust, London, UK
| | - Alan Bainbridge
- Medical Physics and Biomedical Engineering, University College London NHS Foundation Trust, London, UK
| | - Mariya Hristova
- Institute for Women's Health, University College London, London, UK
| | - Ilias Tachtsidis
- Medical Physics and Biomedical Engineering, University College London, London, UK
| | - Cally J Tann
- Adolescent, Reproductive and Child Health Centre, London School of Hygiene and Tropical Medicine, London, UK
| | - Donald Peebles
- Institute for Women's Health, University College London, London, UK
| | - Henrik Hagberg
- Department of Clinical Sciences, Centre of Perinatal Medicine and Health, Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden
- Centre for the Developing Brain, Kings College London, London, UK
| | - Tim G A M Wolfs
- Department of Pediatrics, University of Maastricht, Maastricht, The Netherlands
| | - Nigel Klein
- Paediatric Infectious Diseases and Immunology, Institute of Child Health, University College London, London, UK
| | - Boris W Kramer
- Department of Pediatrics, University of Maastricht, Maastricht, The Netherlands
| | - Bobbi Fleiss
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
- Université de Paris, NeuroDiderot, Inserm, Paris, France
| | | | - Xavier Golay
- Institute of Neurology, University College London, London, UK
| | - Nicola J Robertson
- Institute for Women's Health, University College London, London, UK.
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, UK.
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12
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Changes in Cellular Localization of Inter-Alpha Inhibitor Proteins after Cerebral Ischemia in the Near-Term Ovine Fetus. Int J Mol Sci 2021; 22:ijms221910751. [PMID: 34639091 PMCID: PMC8509455 DOI: 10.3390/ijms221910751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 09/17/2021] [Accepted: 09/21/2021] [Indexed: 12/04/2022] Open
Abstract
Inter-alpha Inhibitor Proteins (IAIPs) are key immunomodulatory molecules. Endogenous IAIPs are present in human, rodent, and sheep brains, and are variably localized to the cytoplasm and nuclei at multiple developmental stages. We have previously reported that ischemia-reperfusion (I/R) reduces IAIP concentrations in the fetal sheep brain. In this study, we examined the effect of I/R on total, cytoplasmic, and nuclear expression of IAIPs in neurons (NeuN+), microglia (Iba1+), oligodendrocytes (Olig2+) and proliferating cells (Ki67+), and their co-localization with histones and the endoplasmic reticulum in fetal brain cells. At 128 days of gestation, fetal sheep were exposed to Sham (n = 6) or I/R induced by cerebral ischemia for 30 min with reperfusion for 7 days (n = 5). Although I/R did not change the total number of IAIP+ cells in the cerebral cortex or white matter, cells with IAIP+ cytoplasm decreased, whereas cells with IAIP+ nuclei increased in the cortex. I/R reduced total neuronal number but did not change the IAIP+ neuronal number. The proportion of cytoplasmic IAIP+ neurons was reduced, but there was no change in the number of nuclear IAIP+ neurons. I/R increased the number of microglia and decreased the total numbers of IAIP+ microglia and nuclear IAIP+ microglia, but not the number of cytoplasmic IAIP+ microglia. I/R was associated with reduced numbers of oligodendrocytes and increased proliferating cells, without changes in the subcellular IAIP localization. IAIPs co-localized with the endoplasmic reticulum and histones. In conclusion, I/R alters the subcellular localization of IAIPs in cortical neurons and microglia but not in oligodendrocytes or proliferating cells. Taken together with the known neuroprotective effects of exogenous IAIPs, we speculate that endogenous IAIPs may play a role during recovery from I/R.
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13
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Davidson JO, Gonzalez F, Gressens P, Gunn AJ. Update on mechanisms of the pathophysiology of neonatal encephalopathy. Semin Fetal Neonatal Med 2021; 26:101267. [PMID: 34274259 DOI: 10.1016/j.siny.2021.101267] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Therapeutic hypothermia is now well established to significantly improve survival without disability after neonatal encephalopathy (NE). To further improve outcomes, we need to better understand the mechanisms of brain injury. The central finding, which offers the potential for neuroprotective and neurorestorative interventions, is that brain damage after perinatal hypoxia-ischemia evolves slowly over time. Although brain cells may die during profound hypoxia-ischemia, even after surprisingly severe insults many cells show transient recovery of oxidative metabolism during a "latent" phase characterized by actively suppressed neural metabolism and activity. Critically, after moderate to severe hypoxia-ischemia, this transient recovery is followed after ~6 h by a phase of secondary deterioration, with delayed seizures, failure of mitochondrial function, cytotoxic edema, and cell death over ~72 h. This is followed by a tertiary phase of remodeling and recovery. This review discusses the mechanisms of injury that occur during the primary, latent, secondary and tertiary phases of injury and potential treatments that target one or more of these phases. By analogy with therapeutic hypothermia, treatment as early as possible in the latent phase is likely to have the greatest potential to prevent injury ("neuroprotection"). In the secondary phase of injury, anticonvulsants can attenuate seizures, but show limited neuroprotection. Encouragingly, there is now increasing preclinical evidence that late, neurorestorative interventions have potential to improve long-term outcomes.
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Affiliation(s)
- Joanne O Davidson
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand.
| | - Fernando Gonzalez
- Department of Pediatrics, University of California, San Francisco, CA, USA.
| | | | - Alistair J Gunn
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand.
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14
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Chakkarapani AA, Aly H, Benders M, Cotten CM, El-Dib M, Gressens P, Hagberg H, Sabir H, Wintermark P, Robertson NJ. Therapies for neonatal encephalopathy: Targeting the latent, secondary and tertiary phases of evolving brain injury. Semin Fetal Neonatal Med 2021; 26:101256. [PMID: 34154945 DOI: 10.1016/j.siny.2021.101256] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In term and near-term neonates with neonatal encephalopathy, therapeutic hypothermia protocols are well established. The current focus is on how to improve outcomes further and the challenge is to find safe and complementary therapies that confer additional protection, regeneration or repair in addition to cooling. Following hypoxia-ischemia, brain injury evolves over three main phases (latent, secondary and tertiary), each with a different brain energy, perfusion, neurochemical and inflammatory milieu. While therapeutic hypothermia has targeted the latent and secondary phase, we now need therapies that cover the continuum of brain injury that spans hours, days, weeks and months after the initial event. Most agents have several therapeutic actions but can be broadly classified under a predominant action (e.g., free radical scavenging, anti-apoptotic, anti-inflammatory, neuroregeneration, and vascular effects). Promising early/secondary phase therapies include Allopurinol, Azithromycin, Exendin-4, Magnesium, Melatonin, Noble gases and Sildenafil. Tertiary phase agents include Erythropoietin, Stem cells and others. We review a selection of promising therapeutic agents on the translational pipeline and suggest a framework for neuroprotection and neurorestoration that targets the evolving injury.
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Affiliation(s)
| | - Hany Aly
- Cleveland Clinic Children's Hospital, Cleveland, OH, USA.
| | - Manon Benders
- Department of Neonatology, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands.
| | - C Michael Cotten
- Department of Pediatrics, Duke University School of Medicine, Durham, NC, USA.
| | - Mohamed El-Dib
- Department of Pediatric Newborn Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
| | - Pierre Gressens
- Université de Paris, NeuroDiderot, Inserm, Paris, France; Centre for the Developing Brain, Department of Division of Imaging Sciences and Biomedical Engineering, King's College London, King's Health Partners, St. Thomas' Hospital, London, SE1 7EH, United Kingdom.
| | - Henrik Hagberg
- Centre for the Developing Brain, Department of Division of Imaging Sciences and Biomedical Engineering, King's College London, King's Health Partners, St. Thomas' Hospital, London, SE1 7EH, United Kingdom; Centre of Perinatal Medicine & Health, Department of Obstetrics and Gynecology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
| | - Hemmen Sabir
- Department of Neonatology and Pediatric Intensive Care, Children's Hospital University of Bonn, Bonn, Germany; German Centre for Neurodegenerative Diseases (DZNE), Bonn, Germany.
| | - Pia Wintermark
- Department of Pediatrics, Division of Newborn Medicine, Montreal Children's Hospital, Research Institute of the McGill University Health Centre, Montreal, QC, Canada.
| | - Nicola J Robertson
- Centre for Clinical Brain Sciences, University of Edinburgh, Chancellor's Building, Edinburgh BioQuarter, Edinburgh, United Kingdom; Institute for Women's Health, University College London, London, United Kingdom.
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15
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Sabir H, Bonifacio SL, Gunn AJ, Thoresen M, Chalak LF. Unanswered questions regarding therapeutic hypothermia for neonates with neonatal encephalopathy. Semin Fetal Neonatal Med 2021; 26:101257. [PMID: 34144931 DOI: 10.1016/j.siny.2021.101257] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Therapeutic hypothermia (TH) is now well established to improve intact survival after neonatal encephalopathy (NE). However, many questions could not be addressed by the randomized controlled trials. Should late preterm newborns with NE be cooled? Is cooling beneficial for mild NE? Is the current therapeutic time window optimal, or could it be shortened or prolonged? Will either milder or deeper hypothermia be effective? Does infection/inflammation exposure in the perinatal period in combination with NE offer potentially beneficial preconditioning or might it obviate hypothermic neuroprotection? In the present review, we dissect the evidence, for whom, when and how can TH best be delivered, and highlight areas that need further research.
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Affiliation(s)
- Hemmen Sabir
- Department of Neonatology and Pediatric Intensive Care, Children's Hospital University of Bonn, Bonn, Germany; German Centre for Neurodegenerative Diseases (DZNE), Bonn, Germany.
| | | | - Alistair J Gunn
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand.
| | - Marianne Thoresen
- Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway; Neonatal Neuroscience, Translational Medicine, University of Bristol, Bristol, United Kingdom.
| | - Lina F Chalak
- Department of Pediatrics, Division of Neonatal-Perinatal Medicine, University of Texas Southwestern Medical School, Dallas, TX, USA.
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16
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Wassink G, Davidson JO, Crisostomo A, Zhou KQ, Galinsky R, Dhillon SK, Lear CA, Bennet L, Gunn AJ. Recombinant erythropoietin does not augment hypothermic white matter protection after global cerebral ischaemia in near-term fetal sheep. Brain Commun 2021; 3:fcab172. [PMID: 34409290 PMCID: PMC8364665 DOI: 10.1093/braincomms/fcab172] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/31/2021] [Indexed: 01/07/2023] Open
Abstract
Therapeutic hypothermia for hypoxic-ischaemic encephalopathy provides partial white matter protection. Recombinant erythropoietin reduces demyelination after hypoxia-ischaemia, but it is unclear whether adjunct erythropoietin treatment can further improve outcomes after therapeutic hypothermia. Term-equivalent fetal sheep received sham-ischaemia (n = 9) or cerebral ischaemia for 30 min (ischaemia-vehicle, n = 8), followed by intravenous infusion of recombinant erythropoietin (ischaemia-Epo, n = 8; 5000 IU/kg bolus dose, then 833.3 IU/kg/h), cerebral hypothermia (ischaemia-hypothermia, n = 8), or recombinant erythropoietin plus hypothermia (ischaemia-Epo-hypothermia, n = 8), from 3 to 72 h post-ischaemia. Foetal brains were harvested at 7 days after cerebral ischaemia. Ischaemia was associated with marked loss of total Olig2-positive oligodendrocytes with reduced density of myelin and linearity of the white matter tracts (P < 0.01), and microglial induction and increased caspase-3-positive apoptosis. Cerebral hypothermia improved the total number of oligodendrocytes and restored myelin basic protein (P < 0.01), whereas recombinant erythropoietin partially improved myelin basic protein density and tract linearity. Both interventions suppressed microgliosis and caspase-3 (P < 0.05). Co-treatment improved 2′,3′-cyclic-nucleotide 3′-phosphodiesterase-myelin density compared to hypothermia, but had no other additive effect. These findings suggest that although hypothermia and recombinant erythropoietin independently protect white matter after severe hypoxia-ischaemia, they have partially overlapping anti-inflammatory and anti-apoptotic effects, with little additive benefit of combination therapy.
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Affiliation(s)
- Guido Wassink
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Joanne O Davidson
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Alyssa Crisostomo
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Kelly Q Zhou
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Robert Galinsky
- The Ritchie Centre, Hudson Institute of Medical Research, Victoria, Australia
| | | | - Christopher A Lear
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, The University of Auckland, Auckland, New Zealand
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17
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Aridas JD, Yawno T, Sutherland AE, Nitsos I, Wong FY, Hunt RW, Ditchfield M, Fahey MC, Malhotra A, Wallace EM, Gunn AJ, Jenkin G, Miller SL. Melatonin augments the neuroprotective effects of hypothermia in lambs following perinatal asphyxia. J Pineal Res 2021; 71:e12744. [PMID: 34032315 DOI: 10.1111/jpi.12744] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 05/19/2021] [Accepted: 05/20/2021] [Indexed: 12/12/2022]
Abstract
Therapeutic hypothermia (TH) is standard care in high-resource birth settings for infants with neonatal encephalopathy. TH is partially effective and adjuvant therapies are needed. Here, we examined whether the antioxidant melatonin (MLT) provides additive benefit with TH, compared to TH alone or MLT alone, to improve recovery from acute encephalopathy in newborn lambs. Immediately before cesarean section delivery, we induced asphyxia in fetal sheep via umbilical cord occlusion until mean arterial blood pressure fell from 55 ± 3 mm Hg in sham controls to 18-20 mm Hg (10.1 ± 1.5 minutes). Lambs were delivered and randomized to control, control + MLT (60 mg iv, from 30 minutes to 24 hours), asphyxia, asphyxia + TH (whole-body cooling to 35.1 ± 0.8°C vs. 38.3 ± 0.17°C in sham controls, from 4-28 hours), asphyxia + MLT, and asphyxia + TH + MLT. At 72 hours, magnetic resonance spectroscopy (MRS) was undertaken, and then brains were collected for neuropathology assessment. Asphyxia induced abnormal brain metabolism on MRS with increased Lactate:NAA (P = .003) and reduced NAA:Choline (P = .005), induced apoptotic and necrotic cell death across gray and white matter brain regions (P < .05), and increased neuroinflammation and oxidative stress (P < .05). TH and MLT were independently associated with region-specific reductions in oxidative stress, inflammation, and cell death, compared to asphyxia alone. There was an interaction between TH and MLT such that the NAA:Choline ratio was not significantly different after asphyxia + TH + MLT compared to sham controls but had a greater overall reduction in neuropathology than either treatment alone. This study demonstrates that, in newborn lambs, combined TH + MLT for neonatal encephalopathy provides significantly greater neuroprotection than either alone. These results will guide the development of further trials for neonatal encephalopathy.
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Affiliation(s)
- James Ds Aridas
- Hudson Institute of Medical Research, The Ritchie Centre, Clayton, Vic., Australia
| | - Tamara Yawno
- Hudson Institute of Medical Research, The Ritchie Centre, Clayton, Vic., Australia
- Department of Obstetrics and Gynaecology, Monash University, Clayton, Vic., Australia
| | - Amy E Sutherland
- Hudson Institute of Medical Research, The Ritchie Centre, Clayton, Vic., Australia
| | - Ilias Nitsos
- Hudson Institute of Medical Research, The Ritchie Centre, Clayton, Vic., Australia
- Department of Obstetrics and Gynaecology, Monash University, Clayton, Vic., Australia
| | - Flora Y Wong
- Hudson Institute of Medical Research, The Ritchie Centre, Clayton, Vic., Australia
- Department of Paediatrics, Monash University, Clayton, Vic., Australia
- Monash Children's Hospital, Monash Health, Clayton, Vic., Australia
| | - Rod W Hunt
- Department of Paediatrics, Monash University, Clayton, Vic., Australia
- Monash Children's Hospital, Monash Health, Clayton, Vic., Australia
- Murdoch Children's Research Institute, Melbourne, Vic., Australia
| | | | - Michael C Fahey
- Hudson Institute of Medical Research, The Ritchie Centre, Clayton, Vic., Australia
- Department of Paediatrics, Monash University, Clayton, Vic., Australia
- Monash Children's Hospital, Monash Health, Clayton, Vic., Australia
| | - Atul Malhotra
- Hudson Institute of Medical Research, The Ritchie Centre, Clayton, Vic., Australia
- Department of Paediatrics, Monash University, Clayton, Vic., Australia
- Monash Children's Hospital, Monash Health, Clayton, Vic., Australia
| | - Euan M Wallace
- Hudson Institute of Medical Research, The Ritchie Centre, Clayton, Vic., Australia
- Department of Obstetrics and Gynaecology, Monash University, Clayton, Vic., Australia
| | - Alistair J Gunn
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Graham Jenkin
- Hudson Institute of Medical Research, The Ritchie Centre, Clayton, Vic., Australia
- Department of Obstetrics and Gynaecology, Monash University, Clayton, Vic., Australia
| | - Suzanne L Miller
- Hudson Institute of Medical Research, The Ritchie Centre, Clayton, Vic., Australia
- Department of Obstetrics and Gynaecology, Monash University, Clayton, Vic., Australia
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18
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Maeda Y, Lear CA, Beacom MJ, Davidson JO, Zhou KQ, Gunning M, Ikeda T, Gunn AJ, Bennet L. Transient effects of forebrain ischemia on fetal heart rate variability in fetal sheep. Am J Physiol Regul Integr Comp Physiol 2021; 320:R916-R924. [PMID: 33881362 DOI: 10.1152/ajpregu.00032.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fetal heart rate variability (FHRV) is a key index of antenatal and intrapartum fetal well-being. FHRV is well established to be mediated by both arms of the autonomic nervous system, but it remains unknown whether higher centers in the forebrain contribute to FHRV. We tested the hypothesis that selective forebrain ischemia would impair the generation of FHRV. Sixteen chronically instrumented near-term fetal sheep were subjected to either forebrain ischemia induced by bilateral carotid occlusion or sham-ischemia for 30 min. Time, frequency, and nonlinear measures of FHRV were assessed during and for seven days after ischemia. Ischemia was associated with profound suppression of electroencephalographic (EEG) power, which remained suppressed throughout the recovery period (P < 0.001). During the first 5 min of ischemia, multiple time and frequency domain measures were increased (all P < 0.05) before returning back to sham levels. A delayed increase in sample entropy was observed during ischemia (P < 0.05). For the first 3 h after ischemia, there was moderate suppression of two measures of FHRV (very-low frequency power and the standard deviation of RR-intervals, both P < 0.05) and increased sample entropy (P < 0.05). Thereafter, all measures of FHRV returned to control levels. In conclusion, profound forebrain ischemia sufficient to lead to severe neural injury had only transient effect on multiple measures of FHRV. These findings suggest that the forebrain makes a limited contribution to FHRV. FHRV therefore primarily originates in the hindbrain and is unlikely to provide meaningful information on forebrain neurodevelopment or metabolism.
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Affiliation(s)
- Yoshiki Maeda
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand.,The Department of Obstetrics and Gynaecology, Mie University, Mie, Japan
| | - Christopher A Lear
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Michael J Beacom
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Joanne O Davidson
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Kelly Q Zhou
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Mark Gunning
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Tomoaki Ikeda
- The Department of Obstetrics and Gynaecology, Mie University, Mie, Japan
| | - Alistair J Gunn
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
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19
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Hatayama K, Stonestreet BS. High mobility group box-1 protein as a therapeutic target in perinatal hypoxic-ischemic brain injury. Neural Regen Res 2021; 16:2006-2007. [PMID: 33642380 PMCID: PMC8343332 DOI: 10.4103/1673-5374.308092] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Affiliation(s)
- Kazuki Hatayama
- Department of Pediatrics, Women & Infants hospital of Rhode Island, The Alpert Medical School of Brown University, Providence, RI, USA
| | - Barbara S Stonestreet
- Department of Pediatrics, Women & Infants hospital of Rhode Island, The Alpert Medical School of Brown University, Providence, RI, USA
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20
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Zhou KQ, Davidson JO, Bennet L, Gunn AJ. Combination treatments with therapeutic hypothermia for hypoxic-ischemic neuroprotection. Dev Med Child Neurol 2020; 62:1131-1137. [PMID: 32614467 DOI: 10.1111/dmcn.14610] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/15/2020] [Indexed: 12/12/2022]
Abstract
Therapeutic hypothermia is now proven to reduce death or disability in term and near-term born infants with moderate to severe hypoxic-ischemic encephalopathy. Nevertheless, many infants still survive with disability, despite treatment with hypothermia. Recent preclinical and clinical studies suggest that current protocols for therapeutic hypothermia are near-optimal. The obvious strategy, in addition to improving early initiation of therapeutic hypothermia after birth, is to combine hypothermia with other neuroprotective agents. We review evidence that the mechanisms of action of many promising agents overlap with the anti-excitotoxic, anti-apoptotic, and anti-inflammatory mechanisms of hypothermia, leading to a lack of benefit from combination treatment. Moreover, even apparently beneficial combinations have failed to translate in clinical trials. These considerations highlight the need for preclinical studies to test clinically realistic protocols of timing and duration of treatment, before committing to large randomized controlled trials.
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Affiliation(s)
- Kelly Q Zhou
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Joanne O Davidson
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, The University of Auckland, Auckland, New Zealand
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21
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Kovács V, Remzső G, Tóth-Szűki V, Varga V, Németh J, Domoki F. Inhaled H 2 or CO 2 Do Not Augment the Neuroprotective Effect of Therapeutic Hypothermia in a Severe Neonatal Hypoxic-Ischemic Encephalopathy Piglet Model. Int J Mol Sci 2020; 21:E6801. [PMID: 32948011 PMCID: PMC7555370 DOI: 10.3390/ijms21186801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 09/09/2020] [Accepted: 09/14/2020] [Indexed: 12/24/2022] Open
Abstract
Hypoxic-ischemic encephalopathy (HIE) is still a major cause of neonatal death and disability as therapeutic hypothermia (TH) alone cannot afford sufficient neuroprotection. The present study investigated whether ventilation with molecular hydrogen (2.1% H2) or graded restoration of normocapnia with CO2 for 4 h after asphyxia would augment the neuroprotective effect of TH in a subacute (48 h) HIE piglet model. Piglets were randomized to untreated naïve, control-normothermia, asphyxia-normothermia (20-min 4%O2-20%CO2 ventilation; Tcore = 38.5 °C), asphyxia-hypothermia (A-HT, Tcore = 33.5 °C, 2-36 h post-asphyxia), A-HT + H2, or A-HT + CO2 treatment groups. Asphyxia elicited severe hypoxia (pO2 = 19 ± 5 mmHg) and mixed acidosis (pH = 6.79 ± 0.10). HIE development was confirmed by altered cerebral electrical activity and neuropathology. TH was significantly neuroprotective in the caudate nucleus but demonstrated virtually no such effect in the hippocampus. The mRNA levels of apoptosis-inducing factor and caspase-3 showed a ~10-fold increase in the A-HT group compared to naïve animals in the hippocampus but not in the caudate nucleus coinciding with the region-specific neuroprotective effect of TH. H2 or CO2 did not augment TH-induced neuroprotection in any brain areas; rather, CO2 even abolished the neuroprotective effect of TH in the caudate nucleus. In conclusion, the present findings do not support the use of these medical gases to supplement TH in HIE management.
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MESH Headings
- Acidosis/blood
- Acidosis/etiology
- Acidosis/prevention & control
- Administration, Inhalation
- Animals
- Animals, Newborn
- Apoptosis Inducing Factor/biosynthesis
- Apoptosis Inducing Factor/genetics
- Asphyxia Neonatorum/complications
- Asphyxia Neonatorum/drug therapy
- Asphyxia Neonatorum/therapy
- Brain Damage, Chronic/etiology
- Brain Damage, Chronic/prevention & control
- Brain-Derived Neurotrophic Factor/biosynthesis
- Brain-Derived Neurotrophic Factor/genetics
- Carbon Dioxide/administration & dosage
- Carbon Dioxide/therapeutic use
- Carbon Dioxide/toxicity
- Caspase 3/biosynthesis
- Caspase 3/genetics
- Caudate Nucleus/pathology
- Cerebral Cortex/metabolism
- Cerebral Cortex/pathology
- Disease Models, Animal
- Drug Evaluation, Preclinical
- Electroencephalography
- Evoked Potentials, Visual/drug effects
- Gene Expression Regulation/drug effects
- Hippocampus/pathology
- Hydrogen/administration & dosage
- Hydrogen/analysis
- Hydrogen/therapeutic use
- Hypothermia, Induced
- Hypoxia-Ischemia, Brain/complications
- Hypoxia-Ischemia, Brain/drug therapy
- Hypoxia-Ischemia, Brain/pathology
- Hypoxia-Ischemia, Brain/therapy
- Nerve Tissue Proteins/biosynthesis
- Nerve Tissue Proteins/genetics
- Neuroprotection/drug effects
- Neuroprotective Agents/administration & dosage
- Neuroprotective Agents/therapeutic use
- Organ Specificity
- Random Allocation
- Swine
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Affiliation(s)
- Viktória Kovács
- Department of Physiology, University of Szeged Faculty of Medicine, H-6720 Szeged, Hungary; (G.R.); (V.T.-S.); (V.V.); (J.N.); (F.D.)
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22
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Zhou KQ, Draghi V, Lear CA, Dean JM, Ashton JL, Hou Y, Bennet L, Gunn AJ, Davidson JO. Protection of axonal integrity with 48 or 72 h of cerebral hypothermia in near-term fetal sheep. Pediatr Res 2020; 88:48-56. [PMID: 31234193 DOI: 10.1038/s41390-019-0475-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 06/06/2019] [Accepted: 06/08/2019] [Indexed: 12/14/2022]
Abstract
BACKGROUND Therapeutic hypothermia is partially protective for neonatal hypoxic-ischemic encephalopathy (HIE). Damage to the white matter tracts is highly associated with adverse outcomes after HIE, but the effectiveness and optimal duration of hypothermia to attenuate axonal injury are unclear. METHODS Near-term fetal sheep were randomized to sham control or cerebral ischemia for 30 min with normothermia or cerebral hypothermia from 3 to either 48 or 72 h. Sheep were killed after 7 days. SMI-312-labeled axons and myelin basic protein were quantified in the intragyral white matter of the first and second parasagittal gyri. RESULTS Ischemia was associated with reduced axonal and myelin area fraction (p < 0.05); loss of axonal and myelin linearity (p < 0.05); and thin, sparse axons, with spheroids, compared to dense, linear morphology in sham controls and associated with induction of microglia in an amoeboid morphology. Both ischemia-48 h hypothermia and ischemia-72 h hypothermia improved axonal area fraction and linearity (p < 0.05), although abnormal morphological features were seen in a subset. Microglial induction was partially suppressed by ischemia-48 h hypothermia, with a ramified morphology. CONCLUSIONS These data suggest that therapeutic hypothermia can alleviate post-ischemic axonopathy, in part by suppressing secondary inflammation.
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Affiliation(s)
- Kelly Q Zhou
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Vittoria Draghi
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Christopher A Lear
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Justin M Dean
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Jesse L Ashton
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Yufeng Hou
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - Laura Bennet
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand.
| | - Joanne O Davidson
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
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23
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Cho KH, Davidson JO, Dean JM, Bennet L, Gunn AJ. Cooling and immunomodulation for treating hypoxic-ischemic brain injury. Pediatr Int 2020; 62:770-778. [PMID: 32119180 DOI: 10.1111/ped.14215] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 02/20/2020] [Accepted: 02/27/2020] [Indexed: 12/20/2022]
Abstract
Therapeutic hypothermia is now well established to partially reduce disability in term and near-term infants with moderate-severe hypoxic-ischemic encephalopathy. Preclinical and clinical studies have confirmed that current protocols for therapeutic hypothermia are near optimal. The challenge is now to identify complementary therapies that can further improve outcomes, in combination with therapeutic hypothermia. Overall, anti-excitatory and anti-apoptotic agents have shown variable or even no benefit in combination with hypothermia, suggesting overlapping mechanisms of neuroprotection. Inflammation appears to play a critical role in the pathogenesis of injury in the neonatal brain, and thus, there is potential for drugs with immunomodulatory properties that target inflammation to be used as a therapy in neonates. In this review, we examine the evidence for neuroprotection with immunomodulation after hypoxia-ischemia. For example, stem cell therapy can reduce inflammation, increase cell survival, and promote cell maturation and repair. There are also encouraging preclinical data from small animals suggesting that stem cell therapy can augment hypothermic neuroprotection. However, there is conflicting evidence, and rigorous testing in translational animal models is now needed.
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Affiliation(s)
- Kenta Ht Cho
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Joanne O Davidson
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Justin M Dean
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, The University of Auckland, Auckland, New Zealand
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24
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Chawla S, Bates SV, Shankaran S. Is It Time for a Randomized Controlled Trial of Hypothermia for Mild Hypoxic-Ischemic Encephalopathy? J Pediatr 2020; 220:241-244. [PMID: 31952851 PMCID: PMC8462395 DOI: 10.1016/j.jpeds.2019.11.030] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 11/04/2019] [Accepted: 11/20/2019] [Indexed: 12/29/2022]
Affiliation(s)
- Sanjay Chawla
- Department of Pediatrics, Wayne State University School of Medicine, Detroit, MI
| | - Sara V. Bates
- Department of Pediatrics, Harvard Medical School, Boston, MA
| | - Seetha Shankaran
- Department of Pediatrics, Wayne State University School of Medicine, Detroit, MI.
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25
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Wassink G, Davidson JO, Fraser M, Yuill CA, Bennet L, Gunn AJ. Non-additive effects of adjunct erythropoietin therapy with therapeutic hypothermia after global cerebral ischaemia in near-term fetal sheep. J Physiol 2020; 598:999-1015. [PMID: 31912503 DOI: 10.1113/jp279131] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 01/02/2020] [Indexed: 01/26/2023] Open
Abstract
KEY POINTS Recombinant human erythropoietin (rEpo) is neuroprotective in immature animals, but it is unclear whether the combination of high-dose rEpo therapy with therapeutic hypothermia can further improve outcomes. Hypothermia and rEpo independently improved neuronal survival, with greater improvement with hypothermia, and similarly reduced numbers of caspase-3 positive cells and reactive microglia after 7 days recovery. Hypothermia, but not rEpo, was associated with markedly improved EEG power, whereas both interventions improved recovery of EEG frequency. There was no significant improvement in any outcome after combined rEpo and hypothermia compared with hypothermia alone, and of concern, the combination was associated with increased numbers of cortical caspase-3-positive cells compared with ischaemia-hypothermia. These data suggest that the mechanisms of neuroprotection with hypothermia and rEpo overlap and, thus, high-dose rEpo infusion does not appear to be an effective adjunct therapy for therapeutic hypothermia. ABSTRACT Therapeutic hypothermia for hypoxic-ischaemic encephalopathy (HIE) provides incomplete neuroprotection. Recombinant human erythropoietin (rEpo) is neuroprotective in immature animals, but it is unclear whether adjunct rEpo therapy with therapeutic hypothermia can further improve outcomes. Near-term fetal sheep received sham-ischaemia (n = 9) or global cerebral ischaemia for 30 min (ischaemia-vehicle, n = 8), followed by intravenous infusion of rEpo (ischaemia-Epo, n = 8; 5000 U/kg loading dose, then 833.3 U/kg/h), cerebral hypothermia (ischaemia-hypothermia, n = 8), or rEpo plus hypothermia (ischaemia-Epo-hypothermia, n = 8), from 3 to 72 h post ischaemia. Fetal brains were collected 7 days after cerebral ischaemia. Cerebral ischaemia was associated with severe neuronal loss and microglial induction in the parasagittal cortex and subcortical regions. Hypothermia reduced overall neuronal loss, cortical caspase-3 and reactive microglia in the striatum and cortex, with greater recovery of electroencephalographic (EEG) power and spectral edge (SEF) from 48 h onwards. rEpo independently improved neuronal survival in the parasagittal cortex, hippocampal CA4 and thalamus, and reduced cortical caspase-3 and activated microglia in striatal and cortical areas, with greater SEF from 120 h onwards. However, ischaemia-Epo-hypothermia did not further improve outcomes compared with ischaemia-hypothermia and was associated with increased numbers of cortical caspase-3-positive cells. These findings suggest that although delayed, prolonged treatment with both hypothermia and rEpo are independently neuroprotective, they have overlapping anti-inflammatory and anti-apoptotic mechanisms, such that the delayed, high-dose rEpo infusion for 3 days did not materially augment neuroprotection with therapeutic hypothermia.
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Affiliation(s)
- Guido Wassink
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, New Zealand
| | - Joanne O Davidson
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, New Zealand
| | - Mhoyra Fraser
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, New Zealand
| | - Caroline A Yuill
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, New Zealand
| | - Laura Bennet
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, New Zealand
| | - Alistair J Gunn
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, New Zealand
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26
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Abbasi H, Unsworth CP. Electroencephalogram studies of hypoxic ischemia in fetal and neonatal animal models. Neural Regen Res 2020; 15:828-837. [PMID: 31719243 PMCID: PMC6990791 DOI: 10.4103/1673-5374.268892] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Alongside clinical achievements, experiments conducted on animal models (including primate or non-primate) have been effective in the understanding of various pathophysiological aspects of perinatal hypoxic/ischemic encephalopathy (HIE). Due to the reasonably fair degree of flexibility with experiments, most of the research around HIE in the literature has been largely concerned with the neurodevelopmental outcome or how the frequency and duration of HI seizures could relate to the severity of perinatal brain injury, following HI insult. This survey concentrates on how EEG experimental studies using asphyxiated animal models (in rodents, piglets, sheep and non-human primate monkeys) provide a unique opportunity to examine from the exact time of HI event to help gain insights into HIE where human studies become difficult.
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Affiliation(s)
- Hamid Abbasi
- Department of Engineering Science, the University of Auckland, Auckland, New Zealand
| | - Charles P Unsworth
- Department of Engineering Science, the University of Auckland, Auckland, New Zealand
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27
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Magnesium sulfate: a last roll of the dice for anti-excitotoxicity? Pediatr Res 2019; 86:685-687. [PMID: 31412352 DOI: 10.1038/s41390-019-0539-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 08/02/2019] [Indexed: 11/08/2022]
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28
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Davidson JO, Wassink G, Draghi V, Dhillon SK, Bennet L, Gunn AJ. Limited benefit of slow rewarming after cerebral hypothermia for global cerebral ischemia in near-term fetal sheep. J Cereb Blood Flow Metab 2019; 39:2246-2257. [PMID: 30092709 PMCID: PMC6827112 DOI: 10.1177/0271678x18791631] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The optimal rate of rewarming after therapeutic hypothermia for neonatal hypoxic-ischemic encephalopathy is unknown, although it is widely suggested that slow rewarming is beneficial. Some preclinical studies suggest better outcomes with slower rewarming, but did not control for the duration of hypothermia. In this study, near-term fetal sheep (0.85 gestation) received 30 min cerebral ischemia followed by normothermia, 48 h hypothermia with rapid rewarming over 1 h, 48-h hypothermia with slow rewarming over 24 h, or 72-h hypothermia with rapid rewarming. Slow rewarming after 48 h of hypothermia improved recovery of EEG power compared with rapid rewarming (p < 0.05), but was not different from rapid rewarming after 72 h of hypothermia. At seven days recovery, neuronal survival was partially improved by both fast and slow rewarming after 48-h hypothermia, but less than 72-h hypothermia in the cortex and CA4 (p < 0.05). In conclusion, although electrographic recovery was partially improved by slow rewarming over 24 h following cerebral hypothermia for 48 h, optimal neuroprotection was seen with hypothermia for 72 h with rapid rewarming, suggesting that the overall duration of cooling was the critical determinant of outcomes after therapeutic hypothermia.
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Affiliation(s)
- Joanne O Davidson
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Guido Wassink
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Vittoria Draghi
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | | | - Laura Bennet
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, The University of Auckland, Auckland, New Zealand
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29
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Kalisvaart ACJ, Prokop BJ, Colbourne F. Hypothermia: Impact on plasticity following brain injury. Brain Circ 2019; 5:169-178. [PMID: 31950092 PMCID: PMC6950515 DOI: 10.4103/bc.bc_21_19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 10/28/2019] [Indexed: 12/13/2022] Open
Abstract
Therapeutic hypothermia (TH) is a potent neuroprotectant against multiple forms of brain injury, but in some cases, prolonged cooling is needed. Such cooling protocols raise the risk that TH will directly or indirectly impact neuroplasticity, such as after global and focal cerebral ischemia or traumatic brain injury. TH, depending on the depth and duration, has the potential to broadly affect brain plasticity, especially given the spatial, temporal, and mechanistic overlap with the injury processes that cooling is used to treat. Here, we review the current experimental and clinical evidence to evaluate whether application of TH has any adverse or positive effects on postinjury plasticity. The limited available data suggest that mild TH does not appear to have any deleterious effect on neuroplasticity; however, we emphasize the need for additional high-quality preclinical and clinical work in this area.
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30
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Parga-Belinkie J, Foglia EE, Flibotte J. Caveats of Cooling: Available Evidence and Ongoing Investigations of Therapeutic Hypothermia. Neoreviews 2019; 20:e513-e519. [PMID: 31477599 DOI: 10.1542/neo.20-9-e513] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Therapeutic hypothermia (TH) mitigates the long-term effects of neuronal excitotoxicity and cell death seen in hypoxic-ischemic encephalopathy (HIE). It remains the most evidence-based therapy for HIE, but it is not without clinical controversy. The literature abounds with questions, such as "When should we start cooling-as early as the delivery room?" "Given the efficacy of TH for moderate to severe HIE when started within 6 hours of birth, can we expand the therapy to infants with mild HIE?" "What should the target temperature be?" "What is the optimal duration of treatment?" "Is early discontinuation acceptable if the examination findings normalize?" These questions about TH, its incomplete neurologic rescue, and variations in the delivery of this therapy have prompted this review. This article summarizes changing procedural considerations for TH, the level of neuromonitoring available, the use of sedation, and considerations for neuroimaging during and after TH.
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Affiliation(s)
| | - Elizabeth E Foglia
- Division of Neonatology, Children's Hospital of Philadelphia, Philadelphia, PA
| | - John Flibotte
- Division of Neonatology, Children's Hospital of Philadelphia, Philadelphia, PA
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31
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Lyden PD, Lamb J, Kothari S, Toossi S, Boitano P, Rajput PS. Differential effects of hypothermia on neurovascular unit determine protective or toxic results: Toward optimized therapeutic hypothermia. J Cereb Blood Flow Metab 2019; 39:1693-1709. [PMID: 30461327 PMCID: PMC6727141 DOI: 10.1177/0271678x18814614] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Therapeutic hypothermia (TH) benefits survivors of cardiac arrest and neonatal hypoxic-ischemic injury and may benefit stroke patients. Large TH clinical trials, however, have shown mixed results. Given the substantial pre-clinical literature supporting TH, we explored possible mechanisms for clinical trial variability. Using a standard rodent stroke model (n = 20 per group), we found smaller infarctions after 2 h pre- or post-reperfusion TH compared to 4 h. To explore the mechanism of this discrepancy, we used primary cell cultures of rodent neurons, astrocytes, or endothelial cells subjected to oxygen-glucose deprivation (OGD). Then, cells were randomly assigned to 33℃, 35℃ or 37℃ for varying durations after varying delay times. Both 33 and 35℃ TH effectively preserved all cell types, although 33℃ was superior. Longer cooling durations overcame moderate delays to cooling initiation. In contrast, TH interfered with astrocyte paracrine protection of neurons in a temperature-dependent manner. These findings suggest that longer TH is needed to overcome delays to TH onset, but shorter TH durations may be superior to longer, perhaps due to suppression of astrocytic paracrine support of neurons during injury. We propose a scheme for optimizing TH after cerebral injury to stimulate further studies of cardiac arrest and stroke.
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Affiliation(s)
- Patrick D Lyden
- 1 Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Jessica Lamb
- 1 Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Shweta Kothari
- 1 Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Shahed Toossi
- 1 Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, USA.,2 Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Paul Boitano
- 1 Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Padmesh S Rajput
- 1 Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
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32
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Montaldo P, Lally PJ, Oliveira V, Swamy R, Mendoza J, Atreja G, Kariholu U, Shivamurthappa V, Liow N, Teiserskas J, Pryce R, Soe A, Shankaran S, Thayyil S. Therapeutic hypothermia initiated within 6 hours of birth is associated with reduced brain injury on MR biomarkers in mild hypoxic-ischaemic encephalopathy: a non-randomised cohort study. Arch Dis Child Fetal Neonatal Ed 2019; 104:F515-F520. [PMID: 30425113 PMCID: PMC6788875 DOI: 10.1136/archdischild-2018-316040] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 10/22/2018] [Accepted: 10/23/2018] [Indexed: 11/04/2022]
Abstract
OBJECTIVE To examine the effect of therapeutic hypothermia on MR biomarkers and neurodevelopmental outcomes in babies with mild hypoxic-ischaemic encephalopathy (HIE). DESIGN Non-randomised cohort study. SETTING Eight tertiary neonatal units in the UK and the USA. PATIENTS 47 babies with mild HIE on NICHD neurological examination performed within 6 hours after birth. INTERVENTIONS Whole-body cooling for 72 hours (n=32) or usual care (n=15; of these 5 were cooled for <12 hours). MAIN OUTCOME MEASURES MRI and MR spectroscopy (MRS) within 2 weeks after birth, and a neurodevelopmental outcome assessment at 2 years. RESULTS The baseline characteristics in both groups were similar except for lower 10 min Apgar scores (p=0.02) in the cooled babies. Despite this, the mean (SD) thalamic NAA/Cr (1.4 (0.1) vs 1.6 (0.2); p<0.001) and NAA/Cho (0.67 (0.08) vs 0.89 (0.11); p<0.001) ratios from MRS were significantly higher in the cooled group. Cooled babies had lower white matter injury scores than non-cooled babies (p=0.02). Four (27%) non-cooled babies with mild HIE developed seizures after 6 hours of age, while none of the cooled babies developed seizures (p=0.008). Neurodevelopmental outcomes at 2 years were available in 40 (85%) of the babies. Adverse outcomes were seen in 2 (14.3%) non-cooled babies, and none of the cooled babies (p=0.09). CONCLUSIONS Therapeutic hypothermia may have a neuroprotective effect in babies with mild HIE, as demonstrated by improved MRS biomarkers and reduced white matter injury on MRI. This may warrant further evaluation in adequately powered randomised controlled trials.
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Affiliation(s)
- Paolo Montaldo
- Centre for Perinatal Neuroscience, Imperial College London, London, UK
| | - Peter J Lally
- Centre for Perinatal Neuroscience, Imperial College London, London, UK
| | - Vânia Oliveira
- Centre for Perinatal Neuroscience, Imperial College London, London, UK
| | - Ravi Swamy
- Centre for Perinatal Neuroscience, Imperial College London, London, UK
| | - Josephine Mendoza
- Centre for Perinatal Neuroscience, Imperial College London, London, UK
| | - Gaurav Atreja
- Neonatal Unit, Imperial Healthcare NHS Trust, London, UK
| | - Ujwal Kariholu
- Neonatal Unit, Imperial Healthcare NHS Trust, London, UK
| | | | - Natasha Liow
- Neonatal Unit, Imperial Healthcare NHS Trust, London, UK
| | | | - Russell Pryce
- Oliver Fisher Neonatal Unit, Medway NHS Hospital Foundation Trust, Gillingham, UK
| | - Aung Soe
- Oliver Fisher Neonatal Unit, Medway NHS Hospital Foundation Trust, Gillingham, UK
| | - Seetha Shankaran
- Perinatal-Neonatal Medicine, Wayne State University, Detroit, Michigan, USA
| | - Sudhin Thayyil
- Centre for Perinatal Neuroscience, Imperial College London, London, UK
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33
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Enweronu‐Laryea C, Martinello KA, Rose M, Manu S, Tann CJ, Meek J, Ahor‐Essel K, Boylan GB, Robertson NJ. Core temperature after birth in babies with neonatal encephalopathy in a sub-Saharan African hospital setting. J Physiol 2019; 597:4013-4024. [PMID: 31168907 PMCID: PMC6767688 DOI: 10.1113/jp277820] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 04/25/2019] [Indexed: 01/06/2023] Open
Abstract
KEY POINTS Therapeutic hypothermia (HT) to 33.0-34.0°C for 72 h provides optimal therapy for infants with neonatal encephalopathy (NE) in high-resource settings. HT is not universally implemented in low- and middle-income countries as a result of both limited resources and evidence. Facilitated passive cooling, comprising infants being allowed to passively lower their body temperature in the days after birth, is an emerging practice in some West African neonatal units. In this observational study, we demonstrate that infants undergoing facilitated passive cooling in a neonatal unit in Accra, Ghana, achieve temperatures within the HT target range ∼20% of the 72 h. Depth of HT fluctuates and can be excessive, as well as not maintained, especially after 24 h. Sustained and deeper passive cooling was evident for severe NE and for those that died. It is important to prevent excessive cooling, to understand that severe NE babies cool more and to be aware of facilitated passive cooling with respect to the design of clinical trials in low- and mid-resource settings. ABSTRACT Neonatal encephalopathy (NE) is a significant worldwide problem with the greatest burden in sub-Saharan Africa. Therapeutic hypothermia (HT), comprising the standard of care for infants with moderate-to-severe NE in settings with sophisticated intensive care, is not available to infants in many sub-Saharan African countries, including Ghana. We prospectively assessed the temperature response in relation to outcome in the 80 h after birth in a cohort of babies with NE undergoing 'facilitated passive cooling' at Korle Bu Teaching Hospital, Accra, Ghana. We hypothesized that NE infants demonstrate passive cooling. Thirteen infants (69% male) ≥36 weeks with moderate-to-severe NE were enrolled. Ambient mean ± SD temperature was 28.3 ± 0.7°C. Infant core temperature was 34.2 ± 1.2°C over the first 24 h and 35.0 ± 1.0°C over 80 h. Nadir mean temperature occurred at 15 h. Temperatures were within target range for HT with respect to 18 ± 14% of measurements within the first 72 h. Axillary temperature was 0.5 ± 0.2°C below core. Three infants died before discharge. Core temperature over 80 h for surviving infants was 35.3 ± 0.9°C and 33.96 ± 0.7°C for those that died (P = 0.043). Temperature profile negatively correlated with Thompson NE score on day 4 (r2 = 0.66): infants with a Thompson score of 0-6 had higher temperatures than those with a score of 7-15 (P = 0.021) and a score of 16+/deceased (P = 0.007). More severe NE was associated with lower core temperatures. Passive cooling is a physiological response after hypoxia-ischaemia; however, the potential neuroprotective effect of facilitated passive cooling is unknown. An awareness of facilitated passive cooling in babies with NE is important for the design of clinical trials of neuroprotection in low and mid resource settings.
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Affiliation(s)
- Christabel Enweronu‐Laryea
- Department of Child HealthUniversity of Ghana School of Medicine and DentistryAccraGhana
- Neonatal Intensive Care UnitKorle Bu Teaching HospitalAccraGhana
| | - Kathryn A Martinello
- Institute for Women's HealthUniversity College LondonLondonUK
- Robinson Research InstituteUniversity of AdelaideAdelaideAustralia
- NeonatologyUniversity College London Hospital NHS Foundation TrustLondonUK
| | - Maggie Rose
- NeonatologyUniversity College London Hospital NHS Foundation TrustLondonUK
| | - Sally Manu
- Neonatal Intensive Care UnitKorle Bu Teaching HospitalAccraGhana
| | - Cally J Tann
- NeonatologyUniversity College London Hospital NHS Foundation TrustLondonUK
- Maternal, Adolescent, Reproductive and Child Health Centre, Department of Infectious Disease EpidemiologyLondon School of Hygiene and Tropical MedicineLondonUK
| | - Judith Meek
- NeonatologyUniversity College London Hospital NHS Foundation TrustLondonUK
| | - Kojo Ahor‐Essel
- Neonatal Intensive Care UnitKorle Bu Teaching HospitalAccraGhana
| | - Geraldine B Boylan
- INFANT Research CentreUniversity College CorkCorkIreland
- Department of Paediatrics & Child HealthUniversity College CorkCorkIreland
| | - Nicola J Robertson
- Institute for Women's HealthUniversity College LondonLondonUK
- Division of NeonatologySidra MedicineDohaQatar
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34
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Draghi V, Wassink G, Zhou KQ, Bennet L, Gunn AJ, Davidson JO. Differential effects of slow rewarming after cerebral hypothermia on white matter recovery after global cerebral ischemia in near-term fetal sheep. Sci Rep 2019; 9:10142. [PMID: 31300687 PMCID: PMC6626025 DOI: 10.1038/s41598-019-46505-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 06/27/2019] [Indexed: 12/27/2022] Open
Abstract
It is widely believed that rewarming slowly after therapeutic hypothermia for hypoxic-ischemic (HI) encephalopathy can improve outcomes, but its impact on white matter injury after HI is unclear. Fetal sheep (0.85 gestation) received 30 min ischemia-normothermia (n = 8), or hypothermia from 3–48 h with rapid spontaneous rewarming over 1 h (ischemia-48 h hypothermia, n = 8), or 48 h with slow rewarming over 24 h (ischemia-slow rewarming, n = 7) or 72 h with rapid rewarming (ischemia-72 h hypothermia, n = 8). Ischemia was associated with loss of total and mature oligodendrocytes and reduced area fraction of myelin basic protein (MBP) and 2′,3′-cyclic nucleotide 3′-phosphodiesterase (CNPase; immature/mature oligodendrocytes) and increased microglia and astrocytes. Total numbers of oligodendrocytes were increased by all hypothermia protocols but only ischemia-72 h hypothermia attenuated loss of mature oligodendrocytes. All hypothermia protocols similarly increased the area fraction of MBP, whereas there was only an intermediate effect on the area fraction of CNPase. Microglia were suppressed by all hypothermia protocols, with the greatest reduction after ischemia-72 h hypothermia, and an intermediate effect after ischemia-slow rewarming. By contrast, induction of astrocytes was significantly reduced only after ischemia-slow rewarming. In conclusion, slow rewarming after hypothermia did not improve oligodendrocyte survival or myelination or suppression of microgliosis compared to fast rewarming, but modestly reduced astrocytosis.
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Affiliation(s)
- V Draghi
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - G Wassink
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - K Q Zhou
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - L Bennet
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - A J Gunn
- Department of Physiology, The University of Auckland, Auckland, New Zealand.
| | - J O Davidson
- Department of Physiology, The University of Auckland, Auckland, New Zealand
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35
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Zhao J, Mu H, Liu L, Jiang X, Wu D, Shi Y, Leak RK, Ji X. Transient selective brain cooling confers neurovascular and functional protection from acute to chronic stages of ischemia/reperfusion brain injury. J Cereb Blood Flow Metab 2019; 39:1215-1231. [PMID: 30334662 PMCID: PMC6668511 DOI: 10.1177/0271678x18808174] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Ischemic injury can be alleviated by the judicious use of hypothermia. However, the optimal regimens and the temporal kinetics of post-stroke neurovascular responses to hypothermic intervention have not been systematically studied. These gaps slow the clinical translation of hypothermia as an anti-stroke therapy. Here, we characterized the effects of transient selective brain hypothermia (TSBH) from the hyperacute to chronic stages of focal ischemia/reperfusion brain injury induced by transient middle cerebral artery occlusion in mice. A simple cooling device was used to induce TSBH during cerebral ischemia. This treatment reduced mortality from 31.8% to 0% and improved neurological outcomes for at least 35 days post-injury. TSBH mitigated blood-brain barrier leakage during the hyperacute and acute injury stages (1-23 h post-reperfusion). This early protection of the blood-brain barrier was associated with anti-inflammatory phenotypic polarization of microglia/macrophages, reduced production of pro-inflammatory cytokines, and less brain infiltration of neutrophils and macrophages during the subacute injury stage (three days post-reperfusion). TSBH elicited enduring protective effects on both grey and white matter for at least 35 days post-injury and preserved the long-term electrophysiological function of fiber tracts. In conclusion, TSBH ameliorates ischemia/reperfusion injury in the neurovascular unit from hyperacute to chronic injury stages after experimental stroke.
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Affiliation(s)
- Jingyan Zhao
- 1 Department of Neurology and China-America Institute of Neuroscience, Xuanwu Hospital, Capital Medical University, Beijing, China.,2 Stroke Center, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,3 Pittsburgh Institute of Brain Disorders & Recovery and Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Hongfeng Mu
- 3 Pittsburgh Institute of Brain Disorders & Recovery and Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Liqiang Liu
- 2 Stroke Center, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,3 Pittsburgh Institute of Brain Disorders & Recovery and Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Xiaoyan Jiang
- 3 Pittsburgh Institute of Brain Disorders & Recovery and Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Di Wu
- 1 Department of Neurology and China-America Institute of Neuroscience, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Yejie Shi
- 3 Pittsburgh Institute of Brain Disorders & Recovery and Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Rehana K Leak
- 4 Graduate School of Pharmaceutical Sciences, Duquesne University, Pittsburgh, PA, USA
| | - Xunming Ji
- 1 Department of Neurology and China-America Institute of Neuroscience, Xuanwu Hospital, Capital Medical University, Beijing, China.,2 Stroke Center, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,5 Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China
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36
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O'Brien CE, Santos PT, Kulikowicz E, Reyes M, Koehler RC, Martin LJ, Lee JK. Hypoxia-Ischemia and Hypothermia Independently and Interactively Affect Neuronal Pathology in Neonatal Piglets with Short-Term Recovery. Dev Neurosci 2019; 41:17-33. [PMID: 31108487 DOI: 10.1159/000496602] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 01/06/2019] [Indexed: 12/25/2022] Open
Abstract
Therapeutic hypothermia is the standard of clinical care for moderate neonatal hypoxic-ischemic encephalopathy. We investigated the independent and interactive effects of hypoxia-ischemia (HI) and temperature on neuronal survival and injury in basal ganglia and cerebral cortex in neonatal piglets. Male piglets were randomized to receive HI injury or sham procedure followed by 29 h of normothermia, sustained hypothermia induced at 2 h, or hypothermia with rewarming during fentanyl-nitrous oxide anesthesia. Viable and injured neurons and apoptotic profiles were counted in the anterior putamen, posterior putamen, and motor cortex at 29 h after HI injury or sham procedure. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) identified genomic DNA fragmentation to confirm cell death. Though hypothermia after HI preserved viable neurons in the anterior and posterior putamen, hypothermia prevented neuronal injury in only the anterior putamen. Hypothermia initiated 2 h after injury did not protect against apoptotic cell death in either the putamen or motor cortex, and rewarming from hypothermia was associated with increased apoptosis in the motor cortex. In non-HI shams, sustained hypothermia during anesthesia was associated with neuronal injury and corresponding viable neuron loss in the anterior putamen and motor cortex. TUNEL confirmed increased neurodegeneration in the putamen of hypothermic shams. Anesthetized, normothermic shams did not show abnormal neuronal cytopathology in the putamen or motor cortex, thereby demonstrating minimal contribution of the anesthetic regimen to neuronal injury during normothermia. We conclude that the efficacy of hypothermic protection after HI is region specific and that hypothermia during anesthesia in the absence of HI may be associated with neuronal injury in the developing brain. Studies examining the potential interactions between hypothermia and anesthesia, as well as with longer durations of hypothermia, are needed.
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Affiliation(s)
- Caitlin E O'Brien
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland, USA,
| | - Polan T Santos
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland, USA
| | - Ewa Kulikowicz
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland, USA
| | - Michael Reyes
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland, USA
| | - Raymond C Koehler
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland, USA
| | - Lee J Martin
- Department of Pathology, Johns Hopkins University, Baltimore, Maryland, USA.,Pathobiology Graduate Training Program, Johns Hopkins University, Baltimore, Maryland, USA
| | - Jennifer K Lee
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland, USA.,Pathobiology Graduate Training Program, Johns Hopkins University, Baltimore, Maryland, USA
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37
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Davidson JO, Battin M, Gunn AJ. Evidence that therapeutic hypothermia should be continued for 72 hours. Arch Dis Child Fetal Neonatal Ed 2019; 104:F225. [PMID: 30194071 DOI: 10.1136/archdischild-2018-315844] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/20/2018] [Indexed: 02/02/2023]
Affiliation(s)
- Joanne O Davidson
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Malcolm Battin
- Newborn Services, Auckland City Hospital, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, University of Auckland, Auckland, New Zealand
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38
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Should therapeutic hypothermia be offered to babies with mild neonatal encephalopathy in the first 6 h after birth? Pediatr Res 2019; 85:442-448. [PMID: 30733613 DOI: 10.1038/s41390-019-0291-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 12/20/2018] [Accepted: 12/30/2018] [Indexed: 12/11/2022]
Abstract
Infants with moderate to severe neonatal encephalopathy (NE) benefit significantly from therapeutic hypothermia, with reduced risk of death or disability. However, the need for therapeutic hypothermia for infants with milder NE remains unclear. It has been suggested that these infants should not be offered therapeutic hypothermia as they may not be at risk for adverse neurodevelopmental outcome and that the balance of risk against potential benefit is unknown. Several key questions need to be answered including first, whether one can define NE in the first 6 h after birth so as to accurately distinguish infants with brain injury who may be at risk for adverse neurodevelopmental consequences. Second, will treatment of infants with mild NE with therapeutic hypothermia improve or even worsen neurological outcomes? Although alternate treatment protocols for mild NE may be feasible, the use of the current approach combined with rigorous avoidance of hyperthermia and initiation of hypothermia as early as possible after birth may promote optimal outcomes. Animal experimental data support the potential for greater benefit for mild HIE compared with moderate to severe HIE. This review will summarize current knowledge of mild NE and the challenges to a trial in this population.
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39
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Zhou KQ, Green CR, Bennet L, Gunn AJ, Davidson JO. The Role of Connexin and Pannexin Channels in Perinatal Brain Injury and Inflammation. Front Physiol 2019; 10:141. [PMID: 30873043 PMCID: PMC6400979 DOI: 10.3389/fphys.2019.00141] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 02/07/2019] [Indexed: 12/21/2022] Open
Abstract
Perinatal brain injury remains a major cause of death and life-long disability. Perinatal brain injury is typically associated with hypoxia-ischemia and/or infection/inflammation. Both hypoxia-ischemia and infection trigger an inflammatory response in the brain. The inflammatory response can contribute to brain cell loss and chronic neuroinflammation leading to neurological impairments. It is now well-established that brain injury evolves over time, and shows a striking spread from injured to previously uninjured regions of the brain. There is increasing evidence that this spread is related to opening of connexin hemichannels and pannexin channels, both of which are large conductance membrane channels found in almost all cell types in the brain. Blocking connexin hemichannels within the first 3 h after hypoxia-ischemia has been shown to improve outcomes in term equivalent fetal sheep but it is important to also understand the downstream pathways linking membrane channel opening with the development of injury in order to identify new therapeutic targets. Open membrane channels release adenosine triphosphate (ATP), and other neuroactive molecules, into the extracellular space. ATP has an important physiological role, but has also been reported to act as a damage-associated molecular pattern (DAMP) signal mediated through specific purinergic receptors and so act as a primary signal 1 in the innate immune system inflammasome pathway. More crucially, extracellular ATP is a key inflammasome signal 2 activator, with purinergic receptor binding triggering the assembly of the multi-protein inflammasome complex. The inflammasome pathway and complex formation contribute to activation of inflammatory caspases, and the release of inflammatory cytokines, including interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-18, and vascular endothelial growth factor (VEGF). We propose that the NOD-like receptor protein-3 (NLRP3) inflammasome, which has been linked to inflammatory responses in models of ischemic stroke and various inflammatory diseases, may be one mechanism by which connexin hemichannel opening especially mediates perinatal brain injury.
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Affiliation(s)
- Kelly Q Zhou
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Colin R Green
- Department of Ophthalmology, The University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Joanne O Davidson
- Department of Physiology, The University of Auckland, Auckland, New Zealand.,Department of Ophthalmology, The University of Auckland, Auckland, New Zealand
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40
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Wassink G, Davidson JO, Dhillon SK, Zhou K, Bennet L, Thoresen M, Gunn AJ. Therapeutic Hypothermia in Neonatal Hypoxic-Ischemic Encephalopathy. Curr Neurol Neurosci Rep 2019; 19:2. [PMID: 30637551 DOI: 10.1007/s11910-019-0916-0] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
PURPOSE OF REVIEW Therapeutic hypothermia reduces death or disability in term and near-term infants with moderate-severe hypoxic-ischemic encephalopathy. Nevertheless, many infants still survive with disability, despite hypothermia, supporting further research in to ways to further improve neurologic outcomes. RECENT FINDINGS Recent clinical and experimental studies have refined our understanding of the key parameters for hypothermic neuroprotection, including timing of initiation, depth, and duration of hypothermia, and subsequent rewarming rate. However, important knowledge gaps remain. There is encouraging clinical evidence from a small phase II trial that combined treatment of hypothermia with recombinant erythropoietin further reduces risk of disability but definitive studies are still needed. In conclusion, recent studies suggest that current protocols for therapeutic hypothermia are near-optimal, and that the key to better neurodevelopmental outcomes is earlier diagnosis and initiation of hypothermia after birth. Further research is essential to find and evaluate ways to further improve outcomes after hypoxic-ischemic encephalopathy, including add-on therapies for therapeutic hypothermia and preventing pyrexia during labor and delivery.
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Affiliation(s)
- Guido Wassink
- Department of Physiology, School of Medical Sciences, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, 92019, New Zealand
| | - Joanne O Davidson
- Department of Physiology, School of Medical Sciences, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, 92019, New Zealand
| | - Simerdeep K Dhillon
- Department of Physiology, School of Medical Sciences, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, 92019, New Zealand
| | - Kelly Zhou
- Department of Physiology, School of Medical Sciences, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, 92019, New Zealand
| | - Laura Bennet
- Department of Physiology, School of Medical Sciences, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, 92019, New Zealand
| | - Marianne Thoresen
- Division of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Neonatal Neuroscience, Translational Health Sciences, University of Bristol, Bristol, UK
| | - Alistair J Gunn
- Department of Physiology, School of Medical Sciences, Faculty of Medical and Health Sciences, University of Auckland, Private Bag, Auckland, 92019, New Zealand.
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41
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Gunn AJ, Thoresen M. Neonatal encephalopathy and hypoxic-ischemic encephalopathy. HANDBOOK OF CLINICAL NEUROLOGY 2019; 162:217-237. [PMID: 31324312 DOI: 10.1016/b978-0-444-64029-1.00010-2] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Acute hypoxic-ischemic encephalopathy around the time of birth remains a major cause of death and life-long disability. The key insight that led to the modern revival of studies of neuroprotection was that, after profound asphyxia, many brain cells show initial recovery from the insult during a short "latent" phase, typically lasting approximately 6h, only to die hours to days later after a "secondary" deterioration characterized by seizures, cytotoxic edema, and progressive failure of cerebral oxidative metabolism. Studies designed around this framework showed that mild hypothermia initiated as early as possible before the onset of secondary deterioration and continued for a sufficient duration to allow the secondary deterioration to resolve is associated with potent, long-lasting neuroprotection. There is now compelling evidence from randomized controlled trials that mild to moderate induced hypothermia significantly improves survival and neurodevelopmental outcomes in infancy and mid-childhood.
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Affiliation(s)
- Alistair J Gunn
- Departments of Physiology and Paediatrics, University of Auckland, Auckland, New Zealand.
| | - Marianne Thoresen
- Department of Physiology University of Oslo, Oslo, Norway; Neonatal Neuroscience, Translational Health Sciences, University of Bristol, Bristol, United Kingdom
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42
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Davies A, Wassink G, Bennet L, Gunn AJ, Davidson JO. Can we further optimize therapeutic hypothermia for hypoxic-ischemic encephalopathy? Neural Regen Res 2019; 14:1678-1683. [PMID: 31169174 PMCID: PMC6585539 DOI: 10.4103/1673-5374.257512] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Perinatal hypoxic-ischemic encephalopathy is a leading cause of neonatal death and disability. Therapeutic hypothermia significantly reduces death and major disability associated with hypoxic-ischemic encephalopathy; however, many infants still experience lifelong disabilities to movement, sensation and cognition. Clinical guidelines, based on strong clinical and preclinical evidence, recommend therapeutic hypothermia should be started within 6 hours of birth and continued for a period of 72 hours, with a target brain temperature of 33.5 ± 0.5°C for infants with moderate to severe hypoxic-ischemic encephalopathy. The clinical guidelines also recommend that infants be rewarmed at a rate of 0.5°C per hour, but this is not based on strong evidence. There are no randomized controlled trials investigating the optimal rate of rewarming after therapeutic hypothermia for infants with hypoxic-ischemic encephalopathy. Preclinical studies of rewarming are conflicting and results were confounded by treatment with sub-optimal durations of hypothermia. In this review, we evaluate the evidence for the optimal start time, duration and depth of hypothermia, and whether the rate of rewarming after treatment affects brain injury and neurological outcomes.
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Affiliation(s)
- Anthony Davies
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Guido Wassink
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Joanne O Davidson
- Department of Physiology, The University of Auckland, Auckland, New Zealand
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43
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Koehler RC, Yang ZJ, Lee JK, Martin LJ. Perinatal hypoxic-ischemic brain injury in large animal models: Relevance to human neonatal encephalopathy. J Cereb Blood Flow Metab 2018; 38:2092-2111. [PMID: 30149778 PMCID: PMC6282216 DOI: 10.1177/0271678x18797328] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
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.
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Affiliation(s)
- Raymond C Koehler
- 1 Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Zeng-Jin Yang
- 1 Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Jennifer K Lee
- 1 Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, MD, USA.,2 The Pathobiology Graduate Training Program, Johns Hopkins University, Baltimore, MD, USA
| | - Lee J Martin
- 2 The Pathobiology Graduate Training Program, Johns Hopkins University, Baltimore, MD, USA.,3 Department of Pathology, Division of Neuropathology, Johns Hopkins University, Baltimore, MD, USA
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44
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Abbasi H, Drury PP, Lear CA, Gunn AJ, Davidson JO, Bennet L, Unsworth CP. EEG sharp waves are a biomarker of striatal neuronal survival after hypoxia-ischemia in preterm fetal sheep. Sci Rep 2018; 8:16312. [PMID: 30397231 PMCID: PMC6218488 DOI: 10.1038/s41598-018-34654-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 10/16/2018] [Indexed: 01/12/2023] Open
Abstract
The timing of hypoxia-ischemia (HI) in preterm infants is often uncertain and there are few biomarkers to determine whether infants are in a treatable stage of injury. We evaluated whether epileptiform sharp waves recorded from the parietal cortex could provide early prediction of neuronal loss after HI. Preterm fetal sheep (0.7 gestation) underwent acute HI induced by complete umbilical cord occlusion for 25 minutes (n = 6) or sham occlusion (control, n = 6). Neuronal survival was assessed 7 days after HI by immunohistochemistry. Sharp waves were quantified manually and using a wavelet-type-2-fuzzy-logic-system during the first 4 hours of recovery. HI resulted in significant subcortical neuronal loss. Sharp waves counted by the automated classifier in the first 30 minutes after HI were associated with greater neuronal survival in the caudate nucleus (r = 0.80), whereas sharp waves between 2–4 hours after HI were associated with reduced neuronal survival (r = −0.83). Manual and automated counts were closely correlated. This study suggests that automated quantification of sharp waves may be useful for early assessment of HI injury in preterm infants. However, the pattern of evolution of sharp waves after HI was markedly affected by the severity of neuronal loss, and therefore early, continuous monitoring is essential.
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Affiliation(s)
- Hamid Abbasi
- Department of Engineering Science, The University of Auckland, Auckland, New Zealand
| | - Paul P Drury
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Christopher A Lear
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Joanne O Davidson
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
| | - Charles P Unsworth
- Department of Engineering Science, The University of Auckland, Auckland, New Zealand.
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Lally PJ, Montaldo P, Oliveira V, Swamy RS, Soe A, Shankaran S, Thayyil S. Residual brain injury after early discontinuation of cooling therapy in mild neonatal encephalopathy. Arch Dis Child Fetal Neonatal Ed 2018; 103:F383-F387. [PMID: 28935718 DOI: 10.1136/archdischild-2017-313321] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 08/04/2017] [Accepted: 08/10/2017] [Indexed: 12/21/2022]
Abstract
We examined the brain injury and neurodevelopmental outcomes in a prospective cohort of 10 babies with mild encephalopathy who had early cessation of cooling therapy. All babies had MRI and spectroscopy within 2 weeks after birth and neurodevelopmental assessment at 2 years. Cooling was prematurely discontinued at a median age of 9 hours (IQR 5-13) due to rapid clinical improvement. Five (50%) had injury on MRI or spectroscopy, and two (20%) had an abnormal neurodevelopmental outcome at 2 years. Premature cessation of cooling therapy in babies with mild neonatal encephalopathy does not exclude residual brain injury and adverse long-term neurodevelopmental outcomes. This study refers to babies recruited into the MARBLE study (NCT01309711, pre-results stage).
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Affiliation(s)
- Peter J Lally
- Centre for Perinatal Neuroscience, Imperial College London, London, UK
| | - Paolo Montaldo
- Centre for Perinatal Neuroscience, Imperial College London, London, UK
| | - Vânia Oliveira
- Centre for Perinatal Neuroscience, Imperial College London, London, UK
| | | | - Aung Soe
- Oliver Fisher Neonatal Unit, Medway Maritime Hospital, Kent, UK
| | - Seetha Shankaran
- Department of Neonatal Perinatal Medicine, Wayne State University, Detroit, Michigan, USA
| | - Sudhin Thayyil
- Centre for Perinatal Neuroscience, Imperial College London, London, UK
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Wassink G, Davidson JO, Lear CA, Juul SE, Northington F, Bennet L, Gunn AJ. A working model for hypothermic neuroprotection. J Physiol 2018; 596:5641-5654. [PMID: 29660115 DOI: 10.1113/jp274928] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 03/28/2018] [Indexed: 01/04/2023] Open
Abstract
Therapeutic hypothermia significantly improves survival without disability in near-term and full-term newborns with moderate to severe hypoxic-ischaemic encephalopathy. However, hypothermic neuroprotection is incomplete. The challenge now is to find ways to further improve outcomes. One major limitation to progress is that the specific mechanisms of hypothermia are only partly understood. Evidence supports the concept that therapeutic cooling suppresses multiple extracellular death signals, including intracellular pathways of apoptotic and necrotic cell death and inappropriate microglial activation. Thus, the optimal depth of induced hypothermia is that which effectively suppresses the cell death pathways after hypoxia-ischaemia, but without inhibiting recovery of the cellular environment. Thus mild hypothermia needs to be continued until the cell environment has recovered until it can actively support cell survival. This review highlights that key survival cues likely include the inter-related restoration of neuronal activity and growth factor release. This working model suggests that interventions that target overlapping mechanisms, such as anticonvulsants, are unlikely to materially augment hypothermic neuroprotection. We suggest that further improvements are most likely to be achieved with late interventions that maximise restoration of the normal cell environment after therapeutic hypothermia, such as recombinant human erythropoietin or stem cell therapy.
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Affiliation(s)
- Guido Wassink
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Joanne O Davidson
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | | | - Sandra E Juul
- Department of Pediatrics, University of Washington, Seattle, WA, USA
| | - Frances Northington
- Department of Pediatrics, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Laura Bennet
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, University of Auckland, Auckland, New Zealand
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Bennet L, Dhillon S, Lear CA, van den Heuij L, King V, Dean JM, Wassink G, Davidson JO, Gunn AJ. Chronic inflammation and impaired development of the preterm brain. J Reprod Immunol 2018; 125:45-55. [DOI: 10.1016/j.jri.2017.11.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 11/13/2017] [Accepted: 11/24/2017] [Indexed: 12/17/2022]
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