1
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Zhao YT, Fallas JA, Saini S, Ueda G, Somasundaram L, Zhou Z, Xavier Raj I, Xu C, Carter L, Wrenn S, Mathieu J, Sellers DL, Baker D, Ruohola-Baker H. F-domain valency determines outcome of signaling through the angiopoietin pathway. EMBO Rep 2021; 22:e53471. [PMID: 34698433 DOI: 10.15252/embr.202153471] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 09/09/2021] [Accepted: 09/16/2021] [Indexed: 12/14/2022] Open
Abstract
Angiopoietins 1 and 2 (Ang1 and Ang2) regulate angiogenesis through their similar F-domains by activating Tie2 receptors on endothelial cells. Despite the similarity in the underlying receptor-binding interaction, the two angiopoietins have opposite effects: Ang1 induces phosphorylation of AKT, strengthens cell-cell junctions, and enhances endothelial cell survival while Ang2 can antagonize these effects, depending on cellular context. To investigate the molecular basis for the opposing effects, we examined the phenotypes of a series of computationally designed protein scaffolds presenting the Ang1 F-domain in a wide range of valencies and geometries. We find two broad phenotypic classes distinguished by the number of presented F-domains: Scaffolds presenting 3 or 4 F-domains have Ang2-like activity, upregulating pFAK and pERK but not pAKT, while scaffolds presenting 6, 8, 12, 30, or 60 F-domains have Ang1-like activity, upregulating pAKT and inducing migration and vascular stability. The scaffolds with 6 or more F-domains display super-agonist activity, producing stronger phenotypes at lower concentrations than Ang1. Tie2 super-agonist nanoparticles reduced blood extravasation and improved blood-brain barrier integrity four days after a controlled cortical impact injury.
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Affiliation(s)
- Yan Ting Zhao
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA.,Oral Health Sciences, School of Dentistry, University of Washington, Seattle, WA, USA
| | - Jorge A Fallas
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Protein Design, University of Washington, Seattle, WA, USA
| | - Shally Saini
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - George Ueda
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Protein Design, University of Washington, Seattle, WA, USA
| | - Logeshwaran Somasundaram
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Ziben Zhou
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Infencia Xavier Raj
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| | - Chunfu Xu
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Lauren Carter
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Protein Design, University of Washington, Seattle, WA, USA
| | - Samuel Wrenn
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Protein Design, University of Washington, Seattle, WA, USA
| | - Julie Mathieu
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA.,Department of Comparative Medicine, University of Washington, Seattle, WA, USA
| | - Drew L Sellers
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA.,Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - David Baker
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Protein Design, University of Washington, Seattle, WA, USA.,Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Hannele Ruohola-Baker
- Department of Biochemistry, University of Washington, Seattle, WA, USA.,Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA.,Oral Health Sciences, School of Dentistry, University of Washington, Seattle, WA, USA.,Department of Bioengineering, University of Washington, Seattle, WA, USA
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2
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Leaston J, Qiao J, Harding IC, Kulkarni P, Gharagouzloo C, Ebong E, Ferris CF. Quantitative Imaging of Blood-Brain Barrier Permeability Following Repetitive Mild Head Impacts. Front Neurol 2021; 12:729464. [PMID: 34659094 PMCID: PMC8515019 DOI: 10.3389/fneur.2021.729464] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 08/24/2021] [Indexed: 12/28/2022] Open
Abstract
This was an exploratory study designed to evaluate the feasibility of a recently established imaging modality, quantitative ultrashort time-to-echo contrast enhanced (QUTE-CE), to follow the early pathology and vulnerability of the blood brain barrier in response to single and repetitive mild head impacts. A closed-head, momentum exchange model was used to produce three consecutive mild head impacts aimed at the forebrain separated by 24 h each. Animals were measured at baseline and within 1 h of impact. Anatomical images were collected to assess the extent of structural damage. QUTE-CE biomarkers for BBB permeability were calculated on 420,000 voxels in the brain and were registered to a bilateral 3D brain atlas providing site-specific information on 118 anatomical regions. Blood brain barrier permeability was confirmed by extravasation of labeled dextran. All head impacts occurred in the absence of any structural brain damage. A single mild head impact had measurable effects on blood brain barrier permeability and was more significant after the second and third impacts. Affected regions included the prefrontal ctx, basal ganglia, hippocampus, amygdala, and brainstem. Our findings support the concerns raised by the healthcare community regarding mild head injuries in participants in organized contact sports and military personnel in basic training and combat.
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Affiliation(s)
| | - Ju Qiao
- Center for Translational Neuroimaging, Northeastern University, Boston, MA, United States
| | - Ian C. Harding
- Department of Bioengineering, Northeastern University, Boston, MA, United States
| | | | - Codi Gharagouzloo
- Imaginostics, Inc., Cambridge, MA, United States
- Center for Translational Neuroimaging, Northeastern University, Boston, MA, United States
| | - Eno Ebong
- Department of Chemical Engineering, Northeastern University, Boston, MA, United States
| | - Craig F. Ferris
- Center for Translational Neuroimaging, Northeastern University, Boston, MA, United States
- Departments of Psychology and Pharmaceutical Sciences, Northeastern University, Boston, MA, United States
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3
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Farajzadeh Khosroshahi S, Yin X, K Donat C, McGarry A, Yanez Lopez M, Baxan N, J Sharp D, Sastre M, Ghajari M. Multiscale modelling of cerebrovascular injury reveals the role of vascular anatomy and parenchymal shear stresses. Sci Rep 2021; 11:12927. [PMID: 34155289 PMCID: PMC8217506 DOI: 10.1038/s41598-021-92371-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 06/07/2021] [Indexed: 01/28/2023] Open
Abstract
Neurovascular injury is often observed in traumatic brain injury (TBI). However, the relationship between mechanical forces and vascular injury is still unclear. A key question is whether the complex anatomy of vasculature plays a role in increasing forces in cerebral vessels and producing damage. We developed a high-fidelity multiscale finite element model of the rat brain featuring a detailed definition of the angioarchitecture. Controlled cortical impacts were performed experimentally and in-silico. The model was able to predict the pattern of blood-brain barrier damage. We found strong correlation between the area of fibrinogen extravasation and the brain area where axial strain in vessels exceeds 0.14. Our results showed that adjacent vessels can sustain profoundly different axial stresses depending on their alignment with the principal direction of stress in parenchyma, with a better alignment leading to larger stresses in vessels. We also found a strong correlation between axial stress in vessels and the shearing component of the stress wave in parenchyma. Our multiscale computational approach explains the unrecognised role of the vascular anatomy and shear stresses in producing distinct distribution of large forces in vasculature. This new understanding can contribute to improving TBI diagnosis and prevention.
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Affiliation(s)
| | - Xianzhen Yin
- Shanghai Institute of Materia Medica, Shanghai, China
| | - Cornelius K Donat
- Department of Brain Sciences, Imperial College London, London, UK
- Centre for Blast Injury Studies, Imperial College London, London, UK
| | - Aisling McGarry
- Department of Brain Sciences, Imperial College London, London, UK
| | | | - Nicoleta Baxan
- Biological Imaging Centre, Imperial College London, London, UK
| | - David J Sharp
- Department of Brain Sciences, Imperial College London, London, UK
| | - Magdalena Sastre
- Department of Brain Sciences, Imperial College London, London, UK
| | - Mazdak Ghajari
- Dyson School of Design Engineering, Imperial College London, London, UK
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4
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Donat CK, Yanez Lopez M, Sastre M, Baxan N, Goldfinger M, Seeamber R, Müller F, Davies P, Hellyer P, Siegkas P, Gentleman S, Sharp DJ, Ghajari M. From biomechanics to pathology: predicting axonal injury from patterns of strain after traumatic brain injury. Brain 2021; 144:70-91. [PMID: 33454735 PMCID: PMC7990483 DOI: 10.1093/brain/awaa336] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 09/01/2020] [Accepted: 09/14/2020] [Indexed: 12/19/2022] Open
Abstract
The relationship between biomechanical forces and neuropathology is key to understanding traumatic brain injury. White matter tracts are damaged by high shear forces during impact, resulting in axonal injury, a key determinant of long-term clinical outcomes. However, the relationship between biomechanical forces and patterns of white matter injuries, associated with persistent diffusion MRI abnormalities, is poorly understood. This limits the ability to predict the severity of head injuries and the design of appropriate protection. Our previously developed human finite element model of head injury predicted the location of post-traumatic neurodegeneration. A similar rat model now allows us to experimentally test whether strain patterns calculated by the model predicts in vivo MRI and histology changes. Using a controlled cortical impact, mild and moderate injuries (1 and 2 mm) were performed. Focal and axonal injuries were quantified with volumetric and diffusion 9.4 T MRI at 2 weeks post injury. Detailed analysis of the corpus callosum was conducted using multi-shell diffusion MRI and histopathology. Microglia and astrocyte density, including process parameters, along with white matter structural integrity and neurofilament expression were determined by quantitative immunohistochemistry. Linear mixed effects regression analyses for strain and strain rate with the employed outcome measures were used to ascertain how well immediate biomechanics could explain MRI and histology changes. The spatial pattern of mechanical strain and strain rate in the injured cortex shows good agreement with the probability maps of focal lesions derived from volumetric MRI. Diffusion metrics showed abnormalities in the corpus callosum, indicating white matter changes in the segments subjected to high strain, as predicted by the model. The same segments also exhibited a severity-dependent increase in glia cell density, white matter thinning and reduced neurofilament expression. Linear mixed effects regression analyses showed that mechanical strain and strain rate were significant predictors of in vivo MRI and histology changes. Specifically, strain and strain rate respectively explained 33% and 28% of the reduction in fractional anisotropy, 51% and 29% of the change in neurofilament expression and 51% and 30% of microglia density changes. The work provides evidence that strain and strain rate in the first milliseconds after injury are important factors in determining patterns of glial and axonal injury and serve as experimental validators of our computational model of traumatic brain injury. Our results provide support for the use of this model in understanding the relationship of biomechanics and neuropathology and can guide the development of head protection systems, such as airbags and helmets.
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Affiliation(s)
- Cornelius K Donat
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
- Royal British Legion Centre for Blast Injury Studies, Imperial College London, London, UK
| | - Maria Yanez Lopez
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
- Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King’s College London, London, UK
| | - Magdalena Sastre
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
| | - Nicoleta Baxan
- Biological Imaging Centre, Central Biomedical Services, Imperial College London, London, UK
| | - Marc Goldfinger
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
| | - Reneira Seeamber
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
| | - Franziska Müller
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
| | - Polly Davies
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
| | - Peter Hellyer
- Centre for Neuroimaging Sciences, King’s College London, London, UK
| | | | - Steve Gentleman
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
| | - David J Sharp
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
- Royal British Legion Centre for Blast Injury Studies, Imperial College London, London, UK
- UK Dementia Research Institute, Care Research and Technology Centre; Imperial College London, London, UK
| | - Mazdak Ghajari
- Royal British Legion Centre for Blast Injury Studies, Imperial College London, London, UK
- Design Engineering, Imperial College London, UK
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5
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Zimmerman KA, Kim J, Karton C, Lochhead L, Sharp DJ, Hoshizaki T, Ghajari M. Player position in American football influences the magnitude of mechanical strains produced in the location of chronic traumatic encephalopathy pathology: A computational modelling study. J Biomech 2021; 118:110256. [PMID: 33545573 PMCID: PMC7612336 DOI: 10.1016/j.jbiomech.2021.110256] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 12/24/2020] [Accepted: 01/10/2021] [Indexed: 12/14/2022]
Abstract
American football players are frequently exposed to head impacts, which can cause concussions and may lead to neurodegenerative diseases such as chronic traumatic encephalopathy (CTE). Player position appears to influence the risk of concussion but there is limited work on its effect on the risk of CTE. Computational modelling has shown that large brain deformations during head impacts co-localise with CTE pathology in sulci. Here we test whether player position has an effect on brain deformation within the sulci, a possible biomechanical trigger for CTE. We physically reconstructed 148 head impact events from video footage of American Football games. Players were separated into 3 different position profiles based on the magnitude and frequency of impacts. A detailed finite element model of TBI was then used to predict Green-Lagrange strain and strain rate across the brain and in sulci. Using a one-way ANOVA, we found that in positions where players were exposed to large magnitude and low frequency impacts (e.g. defensive back and wide receiver), strain and strain rate across the brain and in sulci were highest. We also found that rotational head motion is a key determinant in producing large strains and strain rates in the sulci. Our results suggest that player position has a significant effect on impact kinematics, influencing the magnitude of deformations within sulci, which spatially corresponds to where CTE pathology is observed. This work can inform future studies investigating different player-position risks for concussion and CTE and guide design of prevention systems.
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Affiliation(s)
- K A Zimmerman
- Computational, Cognitive and Clinical Neuroimaging Laboratory, Department of Brain Sciences, Hammersmith Hospital, Imperial College London, London, UK; HEAD Lab, Dyson School of Design Engineering, Imperial College London, UK.
| | - J Kim
- Computational, Cognitive and Clinical Neuroimaging Laboratory, Department of Brain Sciences, Hammersmith Hospital, Imperial College London, London, UK
| | - C Karton
- Neurotrauma Impact Science Laboratory, University of Ottawa, Canada
| | - L Lochhead
- Computational, Cognitive and Clinical Neuroimaging Laboratory, Department of Brain Sciences, Hammersmith Hospital, Imperial College London, London, UK
| | - D J Sharp
- Computational, Cognitive and Clinical Neuroimaging Laboratory, Department of Brain Sciences, Hammersmith Hospital, Imperial College London, London, UK; Care Research & Technology Centre, UK Dementia Research Institute, London, UK
| | - T Hoshizaki
- Neurotrauma Impact Science Laboratory, University of Ottawa, Canada
| | - M Ghajari
- HEAD Lab, Dyson School of Design Engineering, Imperial College London, UK
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6
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Zhao YT, Fallas JA, Saini S, Ueda G, Somasundaram L, Zhou Z, Xavier I, Ehnes D, Xu C, Carter L, Wrenn S, Mathieu J, Sellers DL, Baker D, Ruohola-Baker H. F-domain valency determines outcome of signaling through the angiopoietin pathway. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2020. [PMID: 33501432 PMCID: PMC7836102 DOI: 10.1101/2020.09.19.304188] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Angiopoietin 1 and 2 (Ang1 and Ang2) modulate angiogenesis and vascular homeostasis through engagement of their very similar F-domain modules with the Tie2 receptor tyrosine kinase on endothelial cells. Despite this similarity in the underlying receptor binding interaction, the two angiopoietins have opposite effects: Ang1 induces phosphorylation of protein kinase B (AKT), strengthens cell-cell junctions and enhances endothelial cell survival while Ang2 antagonizes these effects1–4. To investigate the molecular basis for the opposing effects, we examined the protein kinase activation and morphological phenotypes produced by a series of computationally designed protein scaffolds presenting the Ang1 F-domain in a wide range of valencies and geometries. We find two broad phenotypic classes distinguished by the number of presented F-domains: scaffolds presenting 4 F-domains have Ang2 like activity, upregulating pFAK and pERK but not pAKT, and failing to induce cell migration and tube formation, while scaffolds presenting 6 or more F-domains have Ang1 like activity, upregulating pAKT and inducing migration and tube formation. The scaffolds with 8 or more F-domains display superagonist activity, producing stronger phenotypes at lower concentrations than Ang1. When examined in vivo, superagonist icosahedral self-assembling nanoparticles caused significant revascularization in hemorrhagic brains after a controlled cortical impact injury.
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7
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Jannesar S, Salegio EA, Beattie MS, Bresnahan JC, Sparrey CJ. Correlating Tissue Mechanics and Spinal Cord Injury: Patient-Specific Finite Element Models of Unilateral Cervical Contusion Spinal Cord Injury in Non-Human Primates. J Neurotrauma 2020; 38:698-717. [PMID: 33066716 DOI: 10.1089/neu.2019.6840] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Non-human primate (NHP) models are the closest approximation of human spinal cord injury (SCI) available for pre-clinical trials. The NHP models, however, include broader morphological variability that can confound experimental outcomes. We developed subject-specific finite element (FE) models to quantify the relationship between impact mechanics and SCI, including the correlations between FE outcomes and tissue damage. Subject-specific models of cervical unilateral contusion SCI were generated from pre-injury MRIs of six NHPs. Stress and strain outcomes were compared with lesion histology using logit analysis. A parallel generic model was constructed to compare the outcomes of subject-specific and generic models. The FE outcomes were correlated more strongly with gray matter damage (0.29 < R2 < 0.76) than white matter (0.18 < R2 < 0.58). Maximum/minimum principal strain, Von-Mises and Tresca stresses showed the strongest correlations (0.31 < R2 < 0.76) with tissue damage in the gray matter while minimum principal strain, Von-Mises stress, and Tresca stress best predicted white matter damage (0.23 < R2 < 0.58). Tissue damage thresholds varied for each subject. The generic FE model captured the impact biomechanics in two of the four models; however, the correlations between FE outcomes and tissue damage were weaker than the subject-specific models (gray matter [0.25 < R2 < 0.69] and white matter [R2 < 0.06] except for one subject [0.26 < R2 < 0.48]). The FE mechanical outputs correlated with tissue damage in spinal cord white and gray matters, and the subject-specific models accurately mimicked the biomechanics of NHP cervical contusion impacts.
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Affiliation(s)
- Shervin Jannesar
- Mechatronic Systems Engineering, Simon Fraser University, Surrey, British Columbia, Canada.,International Collaboration on Repair Discoveries (ICORD), Vancouver, British Columbia, Canada
| | - Ernesto A Salegio
- Brain and Spinal Injury Center, University of California San Francisco, San Francisco, California, USA
| | - Michael S Beattie
- Brain and Spinal Injury Center, University of California San Francisco, San Francisco, California, USA
| | - Jacqueline C Bresnahan
- Brain and Spinal Injury Center, University of California San Francisco, San Francisco, California, USA
| | - Carolyn J Sparrey
- Mechatronic Systems Engineering, Simon Fraser University, Surrey, British Columbia, Canada.,International Collaboration on Repair Discoveries (ICORD), Vancouver, British Columbia, Canada
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8
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Cherry JD, Babcock KJ, Goldstein LE. Repetitive Head Trauma Induces Chronic Traumatic Encephalopathy by Multiple Mechanisms. Semin Neurol 2020; 40:430-438. [PMID: 32674181 DOI: 10.1055/s-0040-1713620] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Exposure to repetitive neurotrauma increases lifetime risk for developing progressive cognitive deficits, neurobehavioral abnormalities, and chronic traumatic encephalopathy (CTE). CTE is a tau protein neurodegenerative disease first identified in boxers and recently described in athletes participating in other contact sports (notably American football, ice hockey, rugby, and wrestling) and in military veterans with blast exposure. Currently, CTE can only be diagnosed by neuropathological examination of the brain after death. The defining diagnostic lesion of CTE consists of patchy perivascular accumulations of hyperphosphorylated tau protein that localize in the sulcal depths of the cerebral cortex. Neuronal abnormalities, axonopathy, neurovascular dysfunction, and neuroinflammation are triggered by repetitive head impacts (RHIs) and likely act as catalysts for CTE pathogenesis and progression. However, the specific mechanisms that link RHI to CTE are unknown. This review will explore two important areas of CTE pathobiology. First, we will review what is known about the biomechanical properties of RHI that initiate CTE-related pathologies. Second, we will provide an overview of key features of CTE neuropathology and how these contribute to abnormal tau hyperphosphorylation, accumulation, and spread.
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Affiliation(s)
- Jonathan D Cherry
- Boston University Alzheimer's Disease and CTE Center, Boston University School of Medicine, Boston, Massachusetts.,Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, Massachusetts.,Department of Neurology, Boston University School of Medicine, Boston, Massachusetts.,VA Boston Healthcare System, Boston, Massachusetts
| | - Katharine J Babcock
- Boston University Alzheimer's Disease and CTE Center, Boston University School of Medicine, Boston, Massachusetts.,VA Boston Healthcare System, Boston, Massachusetts.,Molecular Aging and Development Laboratory, Boston University School of Medicine, Boston, Massachusetts.,Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts
| | - Lee E Goldstein
- Boston University Alzheimer's Disease and CTE Center, Boston University School of Medicine, Boston, Massachusetts.,Department of Neurology, Boston University School of Medicine, Boston, Massachusetts.,Molecular Aging and Development Laboratory, Boston University School of Medicine, Boston, Massachusetts.,Boston University College of Engineering, Boston University, Boston, Massachusetts
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9
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Monson KL, Converse MI, Manley GT. Cerebral blood vessel damage in traumatic brain injury. Clin Biomech (Bristol, Avon) 2019; 64:98-113. [PMID: 29478776 DOI: 10.1016/j.clinbiomech.2018.02.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 01/12/2018] [Accepted: 02/13/2018] [Indexed: 02/07/2023]
Abstract
Traumatic brain injury is a devastating cause of death and disability. Although injury of brain tissue is of primary interest in head trauma, nearly all significant cases include damage of the cerebral blood vessels. Because vessels are critical to the maintenance of the healthy brain, any injury or dysfunction of the vasculature puts neural tissue at risk. It is well known that these vessels commonly tear and bleed as an immediate consequence of traumatic brain injury. It follows that other vessels experience deformations that are significant though not severe enough to produce bleeding. Recent data show that such subfailure deformations damage the microstructure of the cerebral vessels, altering both their structure and function. Little is known about the prognosis of these injured vessels and their potential contribution to disease development. The objective of this review is to describe the current state of knowledge on the mechanics of cerebral vessels during head trauma and how they respond to the applied loads. Further research on these topics will clarify the role of blood vessels in the progression of traumatic brain injury and is expected to provide insight into improved strategies for treatment of the disease.
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Affiliation(s)
- Kenneth L Monson
- Department of Mechanical Engineering, University of Utah, USA; Department of Bioengineering, University of Utah, USA.
| | | | - Geoffrey T Manley
- Department of Neurological Surgery, University of California, San Francisco, USA
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10
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Ghajari M, Hellyer PJ, Sharp DJ. Computational modelling of traumatic brain injury predicts the location of chronic traumatic encephalopathy pathology. Brain 2017; 140:333-343. [PMID: 28043957 DOI: 10.1093/brain/aww317] [Citation(s) in RCA: 169] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 10/25/2016] [Accepted: 10/25/2016] [Indexed: 12/14/2022] Open
Abstract
Traumatic brain injury can lead to the neurodegenerative disease chronic traumatic encephalopathy. This condition has a clear neuropathological definition but the relationship between the initial head impact and the pattern of progressive brain pathology is poorly understood. We test the hypothesis that mechanical strain and strain rate are greatest in sulci, where neuropathology is prominently seen in chronic traumatic encephalopathy, and whether human neuroimaging observations converge with computational predictions. Three distinct types of injury were simulated. Chronic traumatic encephalopathy can occur after sporting injuries, so we studied a helmet-to-helmet impact in an American football game. In addition, we investigated an occipital head impact due to a fall from ground level and a helmeted head impact in a road traffic accident involving a motorcycle and a car. A high fidelity 3D computational model of brain injury biomechanics was developed and the contours of strain and strain rate at the grey matter-white matter boundary were mapped. Diffusion tensor imaging abnormalities in a cohort of 97 traumatic brain injury patients were also mapped at the grey matter-white matter boundary. Fifty-one healthy subjects served as controls. The computational models predicted large strain most prominent at the depths of sulci. The volume fraction of sulcal regions exceeding brain injury thresholds were significantly larger than that of gyral regions. Strain and strain rates were highest for the road traffic accident and sporting injury. Strain was greater in the sulci for all injury types, but strain rate was greater only in the road traffic and sporting injuries. Diffusion tensor imaging showed converging imaging abnormalities within sulcal regions with a significant decrease in fractional anisotropy in the patient group compared to controls within the sulci. Our results show that brain tissue deformation induced by head impact loading is greatest in sulcal locations, where pathology in cases of chronic traumatic encephalopathy is observed. In addition, the nature of initial head loading can have a significant influence on the magnitude and pattern of injury. Clarifying this relationship is key to understanding the long-term effects of head impacts and improving protective strategies, such as helmet design.
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Affiliation(s)
- Mazdak Ghajari
- Dyson School of Design Engineering, Imperial College London, South Kensington Campus, SW7 2AZ, UK
| | - Peter J Hellyer
- Department of Bioengineering, Imperial College London, South Kensington Campus, SW7 2AZ, UK
| | - David J Sharp
- The Computational, Cognitive and Clinical Neuroimaging Laboratory, Division of Brain Sciences, Imperial College London, W12 0NN, UK
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11
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Novel pharmaceutical treatments for minimal traumatic brain injury and evaluation of animal models and methodologies supporting their development. J Neurosci Methods 2016; 272:69-76. [PMID: 26868733 DOI: 10.1016/j.jneumeth.2016.02.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2015] [Accepted: 02/01/2016] [Indexed: 12/15/2022]
Abstract
BACKGROUND The need for effective pharmaceuticals within animal models of traumatic brain injury (TBI) continues to be paramount, as TBI remains the major cause of brain damage for children and young adults. While preventative measures may act to reduce the incidence of initial blunt trauma, well-tolerated drugs are needed to target the neurologically damaging internal cascade of molecular mechanisms that follow. Such processes, known collectively as the secondary injury phase, include inflammation, excitotoxicity, and apoptosis among other changes still subject to research. In this article positive treatment findings to mitigate this secondary injury in rodent TBI models will be overviewed, and include recent studies on Exendin-4, N-Acetyl-l-cycteine, Salubrinal and Thrombin. CONCLUSIONS These studies provide representative examples of methodologies that can be combined with widely available in vivo rodent models to evaluate therapeutic approaches of translational relevance, as well as drug targets and biochemical cascades that may slow or accelerate the degenerative processes induced by TBI. They employ well-characterized tests such as the novel object recognition task for assessing cognitive deficits. The application of such methodologies provides both decision points and a gateway for implementation of further translational studies to establish the feasibility of clinical efficacy of potential therapeutic interventions.
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12
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Margulies SS, Kilbaugh T, Sullivan S, Smith C, Propert K, Byro M, Saliga K, Costine BA, Duhaime AC. Establishing a Clinically Relevant Large Animal Model Platform for TBI Therapy Development: Using Cyclosporin A as a Case Study. Brain Pathol 2016; 25:289-303. [PMID: 25904045 DOI: 10.1111/bpa.12247] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 02/05/2015] [Indexed: 11/26/2022] Open
Abstract
We have developed the first immature large animal translational treatment trial of a pharmacologic intervention for traumatic brain injury (TBI) in children. The preclinical trial design includes multiple doses of the intervention in two different injury types (focal and diffuse) to bracket the range seen in clinical injury and uses two post-TBI delays to drug administration. Cyclosporin A (CsA) was used as a case study in our first implementation of the platform because of its success in multiple preclinical adult rodent TBI models and its current use in children for other indications. Tier 1 of the therapy development platform assessed the short-term treatment efficacy after 24 h of agent administration. Positive responses to treatment were compared with injured controls using an objective effect threshold established prior to the study. Effective CsA doses were identified to study in Tier 2. In the Tier 2 paradigm, agent is administered in a porcine intensive care unit utilizing neurological monitoring and clinically relevant management strategies, and intervention efficacy is defined as improvement in longer term behavioral endpoints above untreated injured animals. In summary, this innovative large animal preclinical study design can be applied to future evaluations of other agents that promote recovery or repair after TBI.
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13
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Abstract
Traumatic brain injury (TBI) is the leading cause of death and disability for people under 45 years of age. Clinical TBI is often the result of disparate forces resulting in heterogeneous injuries. Preclinical modeling of TBI is a vital tool for studying the complex cascade of metabolic, cellular, and molecular post-TBI events collectively termed secondary injury. Preclinical models also provide an important platform for studying therapeutic interventions. However, modeling TBI in the preclinical setting is challenging, and most models replicate only certain aspects of clinical TBI. This chapter details the most widely used models of preclinical TBI, including the controlled cortical impact, fluid percussion, blast, and closed head models. Each of these models replicates particular critical aspects of clinical TBI. Prior to selecting a preclinical TBI model, it is important to address what aspect of human TBI is being sought to evaluate.
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Blood-Brain Barrier Disruption Is an Early Event That May Persist for Many Years After Traumatic Brain Injury in Humans. J Neuropathol Exp Neurol 2015; 74:1147-57. [DOI: 10.1097/nen.0000000000000261] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
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15
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Hay JR, Johnson VE, Young AM, Smith DH, Stewart W. Blood-Brain Barrier Disruption Is an Early Event That May Persist for Many Years After Traumatic Brain Injury in Humans. J Neuropathol Exp Neurol 2015. [DOI: 10.1093/jnen/74.12.1147] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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16
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Reinwald Y, Leonard KHL, Henstock JR, Whiteley JP, Osborne JM, Waters SL, Levesque P, El Haj AJ. Evaluation of the growth environment of a hydrostatic force bioreactor for preconditioning of tissue-engineered constructs. Tissue Eng Part C Methods 2015; 21:1-14. [PMID: 24967717 DOI: 10.1089/ten.tec.2013.0476] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Bioreactors have been widely acknowledged as valuable tools to provide a growth environment for engineering tissues and to investigate the effect of physical forces on cells and cell-scaffold constructs. However, evaluation of the bioreactor environment during culture is critical to defining outcomes. In this study, the performance of a hydrostatic force bioreactor was examined by experimental measurements of changes in dissolved oxygen (O2), carbon dioxide (CO2), and pH after mechanical stimulation and the determination of physical forces (pressure and stress) in the bioreactor through mathematical modeling and numerical simulation. To determine the effect of hydrostatic pressure on bone formation, chick femur skeletal cell-seeded hydrogels were subjected to cyclic hydrostatic pressure at 0-270 kPa and 1 Hz for 1 h daily (5 days per week) over a period of 14 days. At the start of mechanical stimulation, dissolved O2 and CO2 in the medium increased and the pH of the medium decreased, but remained within human physiological ranges. Changes in physiological parameters (O2, CO2, and pH) were reversible when medium samples were placed in a standard cell culture incubator. In addition, computational modeling showed that the distribution and magnitude of physical forces depends on the shape and position of the cell-hydrogel constructs in the tissue culture format. Finally, hydrostatic pressure was seen to enhance mineralization of chick femur skeletal cell-seeded hydrogels.
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Affiliation(s)
- Yvonne Reinwald
- 1 Institute of Science and Technology in Medicine, University of Keele , Stoke-on-Trent, United Kingdom
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17
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Johnson VE, Meaney DF, Cullen DK, Smith DH. Animal models of traumatic brain injury. HANDBOOK OF CLINICAL NEUROLOGY 2015; 127:115-28. [PMID: 25702213 DOI: 10.1016/b978-0-444-52892-6.00008-8] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Traumatic brain injury (TBI) is a major health issue comprising a heterogeneous and complex array of pathologies. Over the last several decades, numerous animal models have been developed to address the diverse nature of human TBI. The clinical relevance of these models has been a major point of reflection given the poor translation of pharmacologic TBI interventions to the clinic. While previously characterized broadly as either focal or diffuse, this classification is falling out of favor with increased awareness of the overlap in pathologic outcomes between models and an emerging consensus that no one model is sufficient. Moreover, an appreciation of injury biomechanics is essential in recapitulating and interpreting the spectrum of TBI neuropathology observed in various established models of dynamic closed-head TBI. While these models have replicated many specific features of human TBI, an enhanced context with clinical relevancy will facilitate the further elucidation of the mechanisms and treatment of injury.
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Affiliation(s)
- Victoria E Johnson
- Penn Center for Brain Injury and Repair and Department of Neurosurgery, University of Pennsylvania, Philadelphia, PA, USA
| | - David F Meaney
- Departments of Bioengineering and Neurosurgery, University of Pennsylvania, Philadelphia, PA, USA
| | - D Kacy Cullen
- Penn Center for Brain Injury and Repair and Department of Neurosurgery, University of Pennsylvania, Philadelphia, PA, USA
| | - Douglas H Smith
- Penn Center for Brain Injury and Repair and Department of Neurosurgery, University of Pennsylvania, Philadelphia, PA, USA.
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18
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Choo AM, Miller WJ, Chen YC, Nibley P, Patel TP, Goletiani C, Morrison B, Kutzing MK, Firestein BL, Sul JY, Haydon PG, Meaney DF. Antagonism of purinergic signalling improves recovery from traumatic brain injury. ACTA ACUST UNITED AC 2013; 136:65-80. [PMID: 23293266 DOI: 10.1093/brain/aws286] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The recent public awareness of the incidence and possible long-term consequences of traumatic brain injury only heightens the need to develop effective approaches for treating this neurological disease. In this report, we identify a new therapeutic target for traumatic brain injury by studying the role of astrocytes, rather than neurons, after neurotrauma. We use in vivo multiphoton imaging and show that mechanical forces during trauma trigger intercellular calcium waves throughout the astrocytes, and these waves are mediated by purinergic signalling. Subsequent in vitro screening shows that astrocyte signalling through the 'mechanical penumbra' affects the activity of neural circuits distant from the injury epicentre, and a reduction in the intercellular calcium waves within astrocytes restores neural activity after injury. In turn, the targeting of different purinergic receptor populations leads to a reduction in hippocampal cell death in mechanically injured organotypic slice cultures. Finally, the most promising therapeutic candidate from our in vitro screen (MRS 2179, a P2Y1 receptor antagonist) also improves histological and cognitive outcomes in a preclinical model of traumatic brain injury. This work shows the potential of studying astrocyte signalling after trauma to yield new and effective therapeutic targets for treating traumatic brain injury.
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Affiliation(s)
- Anthony M Choo
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
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19
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Abstract
The rising awareness of the long-term health problems associated with concussions re-emphasizes the need for understanding the mechanical etiology of concussions. This article reviews past studies defining the common mechanisms for mild traumatic brain injury and summarizes efforts to convert the external input to the head (force, acceleration, and velocity) into estimates of motions and deformations of the brain that occur during mild traumatic brain injury. Studies of how these mechanical conditions contribute to the cellular mechanisms of damage in mild traumatic brain injury are reviewed. Finally, future directions for improving understanding concussion biomechanics are discussed.
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Frieboes LR, Gupta R. An in-vitro traumatic model to evaluate the response of myelinated cultures to sustained hydrostatic compression injury. J Neurotrauma 2010; 26:2245-56. [PMID: 19645529 DOI: 10.1089/neu.2009.0973] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
While a variety of in-vitro models have been employed to investigate the response of load-bearing tissues to hydrostatic pressure, long-term studies are limited by the need to provide for adequate gas exchange during pressurization. Applying compression in vitro may alter the equilibrium of the system and thereby disrupt the gas exchange kinetics. To address this, several sophisticated compression chamber designs have been developed. However, these systems are limited in the magnitude of pressure that can be applied and may require frequent media changes, thereby eliminating critical autocrine and paracrine signaling factors. To better isolate the cellular response to long-term compression, we created a model that features continuous gas flow through the chamber during pressurization, and a negative feedback control system to rigorously control dissolved oxygen levels. Monitoring dissolved oxygen continuously during pressurization, we find that the ensuing response exhibits characteristics of a second- or higher-order system which can be mathematically modeled using a second-order differential equation. Finally, we use the system to model chronic nerve compression injuries, such as carpal tunnel syndrome and spinal nerve root stenosis, with myelinated neuron-Schwann cell co-cultures. Cell membrane integrity assay results show that co-cultures respond differently to hydrostatic pressure, depending on the magnitude and duration of stimulation. In addition, we find that myelinated Schwann cells proliferate in response to applied hydrostatic compression.
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Affiliation(s)
- Laura R Frieboes
- Department of Biomedical Engineering, University of California-Irvine , Irvine, California, USA
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21
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Cater HL, Sundstrom LE, Morrison B. Temporal development of hippocampal cell death is dependent on tissue strain but not strain rate. J Biomech 2006; 39:2810-8. [PMID: 16289515 DOI: 10.1016/j.jbiomech.2005.09.023] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2005] [Accepted: 09/28/2005] [Indexed: 10/25/2022]
Abstract
Deformation of brain tissue in response to mechanical loading of the head is the root-cause of traumatic brain injury (TBI). Even below ultimate failure limits, deformation activates pathophysiological cascades resulting in delayed cell death. Injury response of soft tissues, such as the chest and spinal cord, is dependent on the product of deformation and velocity, a parameter termed the viscous criterion. We set out to test if hippocampal cell death could be predicted by a similar combination of strain and strain rate and if the viscous criterion was valid for hippocampus. Quantitative prediction of the brain's biological response to mechanical stimuli is difficult to achieve in animal models of TBI, so we utilized an in vitro model of TBI based on hippocampal slice cultures. We quantified the temporal development of cell death after precisely controlled deformations for 30 combinations of strain (0.05-0.50) and strain rate (0.1-50s(-1)) relevant to TBI. Loading conditions for a subset of cultures were verified by analysis of high-speed video. Cell death was found to be significantly dependent on time-post injury, on strain magnitude, and to a lesser extent, on anatomical region by a repeated-measures, three-way ANOVA. The responses of the CA1 and CA3 regions of the hippocampus were not statistically different in contrast to some in vivo TBI studies. Surprisingly, cell death was not dependent on strain rate leading us to conclude that the viscous criterion is not a valid predictor for hippocampal tissue injury. Given the large data set and extensive combinations of biomechanical parameters, predictive mathematical functions relating independent variables (strain, region, and time post-injury) to the resultant cell death were defined. These functions can be used as tolerance criteria to equip finite element models of TBI with the added capability to predict biological consequences.
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Affiliation(s)
- Heather L Cater
- Division of Clinical Neurosciences, Southampton University, SO16 7PX, UK
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22
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Abstract
Animal models of traumatic brain injury (TBI) are used to elucidate primary and secondary sequelae underlying human head injury in an effort to identify potential neuroprotective therapies for developing and adult brains. The choice of experimental model depends upon both the research goal and underlying objectives. The intrinsic ability to study injury-induced changes in behavior, physiology, metabolism, the blood/tissue interface, the blood brain barrier, and/or inflammatory- and immune-mediated responses, makes in vivo TBI models essential for neurotrauma research. Whereas human TBI is a highly complex multifactorial disorder, animal trauma models tend to replicate only single factors involved in the pathobiology of head injury using genetically well-defined inbred animals of a single sex. Although such an experimental approach is helpful to delineate key injury mechanisms, the simplicity and hence inability of animal models to reflect the complexity of clinical head injury may underlie the discrepancy between preclinical and clinical trials of neuroprotective therapeutics. Thus, a search continues for new animal models, which would more closely mimic the highly heterogeneous nature of human TBI, and address key factors in treatment optimization.
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Affiliation(s)
- Ibolja Cernak
- Department of Neuroscience, Georgetown University Medical Center, Washington, D.C. 20057, USA.
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