Neuroprotection Jamie Hutchison, MD Professor of Paediatrics, University of Toronto CCCF Caring for the Brain Injured Patient - I November, 2012
Primary and secondary brain injury timeline Prevention of cell death Primary Injury Secondary injury Outcome Today s Grand Rounds: Global Cerebral Ischemia and Cardiac Arrest Traumatic Brain Injury
Molecular mediators of secondary brain injury Cytokines, Adhesion molecules Apoptotic proteins Reactive oxygen species Excitatory amino acids Heat shock protein PCr/ATP energy failure Brain Injury Therapeutic window Time
Perfusion CT - Global forebrain ischemia forebrain no perfusion Sham hindbrain MICe Dermot Doherty and John Sled, SickKids 2VO
% %rcbf Laser doppler Cerebral blood flow 2VO 2VO Normothermic Hypothermic (32 (37 C) C) 120 100 80 60 40 20 0 0 20 20 40 40 60 60 80 80 100 100 120 120 140 140 Ischemia Time Time (min) (min) Ischemia Jeffrey Shih, MSc, Boston University
Interleukin (IL)-1β is expressed in Neurons Following 2VO ischemia Hippocampus (CA1) IL-1β Neuronal - N Merged Ryan Salewski, MSc, Institute for Medical Science, University of Toronto
Hippocampus (CA1) macrophage/microglia (Iba-1) Sham Normothermia 2VO Hypothermia 2VO Nguyen A, MSc, Institute for Medical Science, University of Toronto
Hypothermia protects against cell death post ischemia Detection of degenerating neurons with FluoroJade B in the hippocampus (CA-1) at 72 h Normothermia sham Normothermia 2VO Hypothermia 2VO Nguyen A, MSc, Institute for Medical Science, University of Toronto
Theoretical paradigm _ Hypothermia
Cardiac Arrest
The Use of Hypothermia Therapy after Pediatric Cardio-Respiratory Arrest - a 5 Centre International Observational Study Conclusions: No Benefit of Hypothermia therapy Equipoise D. Doherty, C. Parshuram, R. Farrell, D. Bohn, A. Hoskote, M. Tucci, A. Joffe, K. Choong, J. Hutchison for the Canadian Critical Care Trials Group Circulation 2009;119:1492-1500.
Hypothermia for Cardiac Arrest in Pediatrics (HypCAP) Pilot study J. Hutchison, A-M. Guerguerian, C. Parshuram, B. Bissonette, Igor Luginbuehl, R. Sananes, A. Hoskote, J. Beca, R. Gaiteiro, H. Frndova, S. Hussain, J. Lacroix
HypCAP Eligibility: - Coma post-ca Informed consent Te = 33-34 C (48 h.) R Te = 36.5-37.5 C (48 h.) N = 38 Masked follow-up 3, 6 and 12 months - Functional and Neuropsychological tests
Outcomes Characteristic N (%) Hypothermia Group (N=19) Normothermi a Group (N=19) P-value PCPC 4-6 at 6 months 13 (68) 10 (53) 0.60 Mortality (28 days) 12 (63) 8 (42) 0.19 No significant increase in adverse effects PCPC = Pediatric Cerebral Performance Category score
https://www.thapca.org/ N=467/820 57% hyperlink
Summary Hypothermia therapy in cardiac arrest and global cerebral ischemia Hypothermia therapy in global cerebral ischemia Potent anti-inflammatory mechanisms Hypothermia therapy in cardiac arrest in children HypCAP pilot complete It is feasible and likely safe THAPCA funded by NHLBI-NIH study in progress
Proposed parallel studies of molecular mechanisms of global cerebral ischemia in mice and cardiac arrest in infants and children Intravital Microscopy forebrain no perfusion Peripheral Neurological Blood Functional ImmunologyOutcomes Death Brain Molecular Expression and Cell Death hindbrain Sham 2VO Time
Traumatic Brain Injury (TBI)
How do we prevent cell death in our patients? Cerebral physiology-based therapy We manage ABCs with great care! We monitor for and control intracranial hypertension We treat HERNIATION as a neurosurgical/medical emergency We tried treating molecular mechanisms of cell death with early institution of hypothermia therapy didn t work!
Monroe- Kellie Doctrine Rogers (1996) Textbook of Pediatric Intensive Care p. 646
Blood: Cerebral Blood Flow The brain has the ability to control its blood supply to match its metabolic requirements Chemical or metabolic by products of cerebral metabolism can alter blood vessel caliber and behavior
Laffey & Kavanagh, New Engl J Med 2002
Mouse Model Weight-drop TBI Steel rod Impounder Bregma Rostral MC Dorsal Caudal Ventral Hutchison, et al. J Neurotrauma 2001 Mikrogianakis, et al. J Neurotrauma 2007
Neuronal apoptosis inhibitory protein (NAIP) at 24 hours following 2 hits Brain Protein (NAIP) 1st Hit 2nd Hit
Brain cell death at 24 hours following 2 hits 2nd Hit Dead Brain Cells 1st Hit
Mikrogianakis, et al., J Neurotrauma 2007
Effect of hypothermia therapy in rodent models of traumatic brain injury (TBI) Reduces cerebral edema, blood brain barrier permeability, inflammation, cerebral atrophy, contusion size, necrotic and apoptotic cell death, axonal injury and mortality and improves neurobehavior scores following TBI in rodents
Hypothermia Paediatric Head Injury Trial (HyP-HIT) Randomized controlled trial of 24 hours of hypothermia therapy in Paediatric patients with Severe TBI 17 centres in Canada, UK and France Trial coordinated by the Chalmers Group and Epidemiology Group (CHEO and University of Ottawa) on behalf of the Canadian Critical Care Trials Group Funded by the Canadian Institutes of Health Research and other granting agencies
HyP-HIT cerebral perfusion pressure (CPP) Hutchison et al. Dev Neuroscience 2010
HyP-HIT Hypotension There was a significant association between the number of hypotensive or low cerebral perfusion pressure events and unfavorable outcome. Hutchison et al. Dev Neuroscience 2010
What more can we do for our patients in the future to develop and test novel therapies? Find the ideal neuroprotective therapy Models of brain injury TBI? + multi-system trauma Study mechanisms of cell death Eg. Apoptosis
Neuroprotection Novel neuroprotective agents in TBI Multiple negative trials and trials in progress NMDA and AMPA receptor antagonists Necrosis and apoptosis inhibitors Immunophilin ligands eg. Cyclosporin A Ovarian hormones - Progesterone Erythropoetin Steroids - CRASH Lancet 2005 Harm Nimodipine Magnesium sulfate, tirilizad and selfotel Review: McConeghy KW, et al. CNS Drugs 2012
Mouse Model Weight-drop TBI Steel rod Impounder Bregma Rostral MC Dorsal Caudal Ventral Hutchison, et al. J Neurotrauma 2001 Mikrogianakis, et al. J Neurotrauma 2007
TAT- NAIP Construct BIR GFP TAT BIR BIR NOD LRR BIR = Baculovirus Inhibitor of apoptosis protein Repeat
Model of cell death in rodent neurons Cleaved PARP Positive cells 16 hours of etoposide Hoechst Cleaved PARP 100 X 100 X
Cleaved PARP following 16 hours of etoposide Cell Death Percentage of Cleaved PARP Positive Cells 30 25 20 15 10 5 0 Negative Control DMSO Alone Etoposide + Control O + Etoposide Alone * Etoposide + TAT-NAIP -BIR123xt Etoposide
Recombinant TAT-GFP-NAIP enters brain cells rapidly (3-4h.) following injection into the peritoneum of mice GFP Hoechst PBS TAT-GFP-NAIP E F
Effect of recombinant TAT- NAIP on area of contusion post-tbi 20 Percent Area of Damage % Damage 15 10 5 * 0 GFP-BIR123xt TBI + NAIP (no TAT) TAT-GFP-BIR123xt TBI + TAT NAIP
Specific Biomarkers May Be Responsive To Neuroprotective Therapy Endothelial cell Molecular Biomarkers Adherent leukocyte: Cytokines Chemokines Endothelial-selectin Soluble adhesion molecules Blood-brain barrier Lipids: Eicosanoids Leukotrienes Sphingolipids Oxidized lipids Astrocyte: S100B Glial fibrillary acid protein Oligodendrocyte: Myelin basic protein Basement membrane Microglia: Cytokines Chemokines Neuron: Neuron-specific enolase Phosphorylated neurofilament H protein
Conclusions Neuroprotection in TBI Prevent secondary brain injury by preventing cerebral hypoxic-ischemia Hypothermia therapy holds promise in cardiac arrest but not in TBI in children Novel anti-inflammatory and anti-apoptotic therapies hold promise Combination therapies or therapeutics may be successful Brain specific biomarkers hold promise as surrogate endpoints for pilot randomized controlled trials of novel neuroprotective agents
Acknowledgements HypCAP, HyP-HIT and Biomarkers in TBI Clinical study coordinators and investigators Rose Gaiteiro, Roxanne Ward, Judy Van Huyse Anne-Marie Guerguerian Laboratory: Technicians: Rachel Shaye, Phil Griffen, Julia Lockwood Graduate students and post-docs: Angelo Mikrogianakis, Natalie Gendron, Arsalan Haqqani, Dermot Doherty, Milly Lo, Ian Sutcliffe, Jeffery Shih, Ryan Salewski, Vera Nenadovic, Anh Nguyen Collaborators: Danica Stanimirovic, Alex MacKenzie, Rand Askalan, Cynthia Hawkins, Sheena Josselyn, Paul Frankland, Martin Post, Mike Salter