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Silverstein AL, Lawson KG, Farhadi HF, Alilain WJ. Contrasting Experimental Rodent Aftercare With Human Clinical Treatment for Cervical Spinal Cord Injury: Bridging the Translational "Valley of Death". J Neurotrauma 2023; 40:2469-2486. [PMID: 37772694 PMCID: PMC10698787 DOI: 10.1089/neu.2023.0314] [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] [Indexed: 09/30/2023] Open
Abstract
More than half of all spinal cord injuries (SCIs) occur at the cervical level and often lead to life-threatening breathing motor dysfunction. The C2 hemisection (C2Hx) and high cervical contusion mouse and rat models of SCI are widely utilized both to understand the pathological effects of SCI and to develop potential therapies. Despite rigorous research effort, pre-clinical therapeutics studied in those animal models of SCI sometimes fail when evaluated in the clinical setting. Differences between standard-of-care treatment for acute SCI administered to clinical populations and experimental animal models of SCI could influence the heterogeneity of outcome between pre-clinical and clinical studies. In this review, we have summarized both the standard clinical interventions used to treat patients with cervical SCI and the various veterinary aftercare protocols used to care for rats and mice after experimentally induced C2Hx and high cervical contusion models of SCI. Through this analysis, we have identified areas of marked dissimilarity between clinical and veterinary protocols and suggest the modification of pre-clinical animal care particularly with respect to analgesia, anticoagulative measures, and stress ulcer prophylaxis. In our discussion, we intend to inspire consideration of potential changes to aftercare for animal subjects of experimental SCI that may help to bridge the translational "Valley of Death" and ultimately contribute more effectively to finding treatments capable of restoring independent breathing function to persons with cervical SCI.
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Affiliation(s)
- Aaron L. Silverstein
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Katelyn G. Lawson
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - H. Francis Farhadi
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
- Department of Neurosurgery, Spinal Cord and Brain Injury Research Center, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Warren J. Alilain
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
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Harris JP, Mietus CJ, Browne KD, Wofford KL, Keating CE, Brown DP, Johnson BN, Wolf JA, Smith DH, Cohen AS, Duda JE, Cullen DK. Neuronal somatic plasmalemmal permeability and dendritic beading caused by head rotational traumatic brain injury in pigs-An exploratory study. Front Cell Neurosci 2023; 17:1055455. [PMID: 37519631 PMCID: PMC10381956 DOI: 10.3389/fncel.2023.1055455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 06/23/2023] [Indexed: 08/01/2023] Open
Abstract
Closed-head traumatic brain injury (TBI) is induced by rapid motion of the head, resulting in diffuse strain fields throughout the brain. The injury mechanism(s), loading thresholds, and neuroanatomical distribution of affected cells remain poorly understood, especially in the gyrencephalic brain. We utilized a porcine model to explore the relationships between rapid head rotational acceleration-deceleration loading and immediate alterations in plasmalemmal permeability within cerebral cortex, sub-cortical white matter, and hippocampus. To assess plasmalemmal compromise, Lucifer yellow (LY), a small cell-impermeant dye, was delivered intraventricularly and diffused throughout the parenchyma prior to injury in animals euthanized at 15-min post-injury; other animals (not receiving LY) were survived to 8-h or 7-days. Plasmalemmal permeability preferentially occurred in neuronal somata and dendrites, but rarely in white matter axons. The burden of LY+ neurons increased based on head rotational kinematics, specifically maximum angular velocity, and was exacerbated by repeated TBI. In the cortex, LY+ cells were prominent in both the medial and lateral gyri. Neuronal membrane permeability was observed within the hippocampus and entorhinal cortex, including morphological changes such as beading in dendrites. These changes correlated with reduced fiber volleys and synaptic current alterations at later timepoints in the hippocampus. Further histological observations found decreased NeuN immunoreactivity, increased mitochondrial fission, and caspase pathway activation in both LY+ and LY- cells, suggesting the presence of multiple injury phenotypes. This exploratory study suggests relationships between plasmalemmal disruptions in neuronal somata and dendrites within cortical and hippocampal gray matter as a primary response in closed-head rotational TBI and sets the stage for future, traditional hypothesis-testing experiments.
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Affiliation(s)
- James P. Harris
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
| | - Constance J. Mietus
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Kevin D. Browne
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
| | - Kathryn L. Wofford
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
| | - Carolyn E. Keating
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
| | - Daniel P. Brown
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
| | - Brian N. Johnson
- Department of Anesthesiology and Critical Care Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Research Institute, Children’s Hospital of Philadelphia, Philadelphia, PA, United States
| | - John A. Wolf
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
| | - Douglas H. Smith
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Akiva S. Cohen
- Department of Anesthesiology and Critical Care Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Research Institute, Children’s Hospital of Philadelphia, Philadelphia, PA, United States
| | - John E. Duda
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - D. Kacy Cullen
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, United States
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Ogino Y, Bernas T, Greer JE, Povlishock JT. Axonal injury following mild traumatic brain injury is exacerbated by repetitive insult and is linked to the delayed attenuation of NeuN expression without concomitant neuronal death in the mouse. Brain Pathol 2021; 32:e13034. [PMID: 34729854 PMCID: PMC8877729 DOI: 10.1111/bpa.13034] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Revised: 09/06/2021] [Accepted: 10/14/2021] [Indexed: 11/30/2022] Open
Abstract
Mild traumatic brain injury (mTBI) affects brain structure and function and can lead to persistent abnormalities. Repetitive mTBI exacerbates the acute phase response to injury. Nonetheless, its long‐term implications remain poorly understood, particularly in the context of traumatic axonal injury (TAI), a player in TBI morbidity via axonal disconnection, synaptic loss and retrograde neuronal perturbation. In contrast to the examination of these processes in the acute phase of injury, the chronic‐phase burden of TAI and/or its implications for retrograde neuronal perturbation or death have received little consideration. To critically assess this issue, murine neocortical tissue was investigated at acute (24‐h postinjury, 24hpi) and chronic time points (28‐days postinjury, 28dpi) after singular or repetitive mTBI induced by central fluid percussion injury (cFPI). Neurons were immunofluorescently labeled for NeuroTrace and NeuN (all neurons), p‐c‐Jun (axotomized neurons) and DRAQ5 (cell nuclei), imaged in 3D and quantified in automated manner. Single mTBI produced axotomy in 10% of neurons at 24hpi and the percentage increased after repetitive injury. The fraction of p‐c‐Jun+ neurons decreased at 28dpi but without neuronal loss (NeuroTrace), suggesting their reorganization and/or repair following TAI. In contrast, NeuN+ neurons decreased with repetitive injury at 24hpi while the corresponding fraction of NeuroTrace+ neurons decreased over 28dpi. Attenuated NeuN expression was linked exclusively to non‐axotomized neurons at 24hpi which extended to the axotomized at 28dpi, revealing a delayed response of the axotomized neurons. Collectively, we demonstrate an increased burden of TAI after repetitive mTBI, which is most striking in the acute phase response to the injury. Our finding of widespread axotomy in large fields of intact neurons contradicts the notion that repetitive mTBI elicits progressive neuronal death, rather, emphasizing the importance of axotomy‐mediated change.
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Affiliation(s)
- Yasuaki Ogino
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Tytus Bernas
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - John E Greer
- Department of Neurosurgery, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA.,Department of Surgery, Hunter Holmes McGuire Veterans Affairs Medical Center, Richmond, Virginia, USA
| | - John T Povlishock
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
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Hernandez ML, Chatlos T, Gorse KM, Lafrenaye AD. Neuronal Membrane Disruption Occurs Late Following Diffuse Brain Trauma in Rats and Involves a Subpopulation of NeuN Negative Cortical Neurons. Front Neurol 2019; 10:1238. [PMID: 31824411 PMCID: PMC6883004 DOI: 10.3389/fneur.2019.01238] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 11/07/2019] [Indexed: 01/20/2023] Open
Abstract
The repercussions of traumatic brain injury (TBI) endure years following the initial insult and involve chronic impairments/disabilities. Studies indicate that these morbidities stem from diffuse pathologies, however, knowledge regarding TBI-mediated diffuse pathologies, and in particular, diffuse neuronal membrane disruption, is limited. Membrane disruption has been shown to occur acutely following injury, primarily within neurons, however, the progression of TBI-induced membrane disruption remains undefined. Therefore, the current study investigated this pathology over a longer temporal profile from 6 h to 4 w following diffuse TBI induced using the central fluid percussion injury (CFPI) model in rats. To visualize membrane disruption, animals received an intracerebroventricular infusion of tagged cell-impermeable dextran 2 h prior to experimental endpoints at 6 h, 1 d, 3 d, 1 w, 2 w, or 4 w post-CFPI. The percentage of total neurons demonstrating dextran uptake, indicative of membrane disruption, was quantified within the lateral neocortex layers V and VI from 6 h to 4 w post-injury. We found that membrane disruption displayed a biphasic pattern, where nearly half of the neurons were membrane disrupted sub-acutely, from 6 h to 3 d post-TBI. At 1 w the membrane disrupted population was dramatically reduced to levels indistinguishable from sham controls. However, by 2 and 4 w following CFPI, approximately half of the neurons analyzed displayed membrane disruption. Moreover, our data revealed that a subset of these late membrane disrupted neurons were NeuN negative (NeuN-). Correlative western blot analyses, however, revealed no difference in NeuN protein expression in the lateral neocortex at any time following injury. Furthermore, the NeuN- membrane disrupted neurons did not co-label with traditional markers of astrocytes, microglia, oligodendrocytes, or NG2 cells. Immunohistochemistry against NeuN, paired with a hematoxylin and eosin counter-stain, was performed to quantify the possibility of overall NeuN+ neuronal loss following CFPI. A NeuN- population was observed consistently in both sham and injured animals regardless of time post-injury. These data suggest that there is a consistent subpopulation of NeuN- neurons within the lateral neocortex regardless of injury and that these NeuN- neurons are potentially more vulnerable to late membrane disruption. Better understanding of membrane disruption could provide insight into the mechanisms of diffuse pathology and lead to the discovery of novel treatments for TBI.
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Affiliation(s)
- Martina L. Hernandez
- Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA, United States
| | - Todd Chatlos
- Department of Neurology, University of California, Davis, Davis, CA, United States
| | - Karen M. Gorse
- Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA, United States
| | - Audrey D. Lafrenaye
- Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA, United States
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An ATF3-CreERT2 Knock-In Mouse for Axotomy-Induced Genetic Editing: Proof of Principle. eNeuro 2019; 6:eN-MNT-0025-19. [PMID: 30993183 PMCID: PMC6464513 DOI: 10.1523/eneuro.0025-19.2019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Revised: 03/18/2019] [Accepted: 03/20/2019] [Indexed: 01/08/2023] Open
Abstract
Genome editing techniques have facilitated significant advances in our understanding of fundamental biological processes, and the Cre-Lox system has been instrumental in these achievements. Driving Cre expression specifically in injured neurons has not been previously possible: we sought to address this limitation in mice using a Cre-ERT2 construct driven by a reliable indicator of axotomy, activating transcription factor 3 (ATF3). When crossed with reporter mice, a significant amount of recombination was achieved (without tamoxifen treatment) in peripherally-projecting sensory, sympathetic, and motoneurons after peripheral nerve crush in hemizygotes (65–80% by 16 d) and was absent in uninjured neurons. Importantly, injury-induced recombination did not occur in Schwann cells distal to the injury, and with a knock-out-validated antibody we verified an absence of ATF3 expression. Functional recovery following sciatic nerve crush in ATF3-deficient mice (both hemizygotes and homozygotes) was delayed, indicating previously unreported haploinsufficiency. In a proof-of-principle experiment, we crossed the ATF3-CreERT2 line with a floxed phosphatase and tensin homolog (PTEN) line and show significantly improved axonal regeneration, as well as more complete recovery of neuromuscular function. We also demonstrate the utility of the ATF3-CreERT2 hemizygous line by characterizing recombination after lateral spinal hemisection (C8/T1), which identified specific populations of ascending spinal cord neurons (including putative spinothalamic and spinocerebellar) and descending supraspinal neurons (rubrospinal, vestibulospinal, reticulospinal and hypothalamic). We anticipate these mice will be valuable in distinguishing axotomized from uninjured neurons of several different classes (e.g., via reporter expression), and in probing the function of any number of genes as they relate to neuronal injury and regeneration.
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