Neuroprotection. Jamie Hutchison, MD Professor of Paediatrics, University of Toronto. CCCF Caring for the Brain Injured Patient - I November, 2012

Transcription

1 Neuroprotection Jamie Hutchison, MD Professor of Paediatrics, University of Toronto CCCF Caring for the Brain Injured Patient - I November, 2012

2 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

3 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

4 Perfusion CT - Global forebrain ischemia forebrain no perfusion Sham hindbrain MICe Dermot Doherty and John Sled, SickKids 2VO

5 % %rcbf Laser doppler Cerebral blood flow 2VO 2VO Normothermic Hypothermic (32 (37 C) C) Ischemia Time Time (min) (min) Ischemia Jeffrey Shih, MSc, Boston University

6 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

7 Hippocampus (CA1) macrophage/microglia (Iba-1) Sham Normothermia 2VO Hypothermia 2VO Nguyen A, MSc, Institute for Medical Science, University of Toronto

8 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

9 Theoretical paradigm _ Hypothermia

10 Cardiac Arrest

11 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:

12 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

13 HypCAP Eligibility: - Coma post-ca Informed consent Te = C (48 h.) R Te = C (48 h.) N = 38 Masked follow-up 3, 6 and 12 months - Functional and Neuropsychological tests

14 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

15 N=467/820 57% hyperlink

16 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

17 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

18 Traumatic Brain Injury (TBI)

19 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!

20 Monroe- Kellie Doctrine Rogers (1996) Textbook of Pediatric Intensive Care p. 646

21 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

22 Laffey & Kavanagh, New Engl J Med 2002

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24 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

25 Neuronal apoptosis inhibitory protein (NAIP) at 24 hours following 2 hits Brain Protein (NAIP) 1st Hit 2nd Hit

26 Brain cell death at 24 hours following 2 hits 2nd Hit Dead Brain Cells 1st Hit

27 Mikrogianakis, et al., J Neurotrauma 2007

28 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

29 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

30 HyP-HIT cerebral perfusion pressure (CPP) Hutchison et al. Dev Neuroscience 2010

31 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

32 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

33 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

34 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

35 TAT- NAIP Construct BIR GFP TAT BIR BIR NOD LRR BIR = Baculovirus Inhibitor of apoptosis protein Repeat

36 Model of cell death in rodent neurons Cleaved PARP Positive cells 16 hours of etoposide Hoechst Cleaved PARP 100 X 100 X

37 Cleaved PARP following 16 hours of etoposide Cell Death Percentage of Cleaved PARP Positive Cells Negative Control DMSO Alone Etoposide + Control O + Etoposide Alone * Etoposide + TAT-NAIP -BIR123xt Etoposide

38 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

39 Effect of recombinant TAT- NAIP on area of contusion post-tbi 20 Percent Area of Damage % Damage * 0 GFP-BIR123xt TBI + NAIP (no TAT) TAT-GFP-BIR123xt TBI + TAT NAIP

40 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

41 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

42 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