1
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Dwyer MKR, Amelinez-Robles N, Polsfuss I, Herbert K, Kim C, Varghese N, Parry TJ, Buller B, Verdoorn TA, Billing CB, Morrison B. NTS-105 decreased cell death and preserved long-term potentiation in an in vitro model of moderate traumatic brain injury. Exp Neurol 2024; 371:114608. [PMID: 37949202 DOI: 10.1016/j.expneurol.2023.114608] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 10/27/2023] [Accepted: 11/05/2023] [Indexed: 11/12/2023]
Abstract
Traumatic brain injury (TBI) is a major cause of hospitalization and death. To mitigate these human costs, the search for effective drugs to treat TBI continues. In the current study, we evaluated the efficacy of the novel neurosteroid, NTS-105, to reduce post-traumatic pathobiology in an in vitro model of moderate TBI that utilizes an organotypic hippocampal slice culture. NTS-105 inhibited activation of the androgen receptor and the mineralocorticoid receptor, partially activated the progesterone B receptor and was not active at the glucocorticoid receptor. Treatment with NTS-105 starting one hour after injury decreased post-traumatic cell death in a dose-dependent manner, with 10 nM NTS-105 being most effective. Post-traumatic administration of 10 nM NTS-105 also prevented deficits in long-term potentiation (LTP) without adversely affecting neuronal activity in naïve cultures. We propose that the high potency pleiotropic action of NTS-105 beneficial effects at multiple receptors (e.g. androgen, mineralocorticoid and progesterone) provides significant mechanistic advantages over native neurosteroids such as progesterone, which lacked clinical success for the treatment of TBI. Our results suggest that this pleiotropic pharmacology may be a promising strategy for the effective treatment of TBI, and future studies should test its efficacy in pre-clinical animal models of TBI.
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Affiliation(s)
- Mary Kate R Dwyer
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, United States of America
| | - Nicolas Amelinez-Robles
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, United States of America
| | - Isabella Polsfuss
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, United States of America
| | - Keondre Herbert
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, United States of America
| | - Carolyn Kim
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, United States of America
| | - Nevin Varghese
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, United States of America
| | - Tom J Parry
- NeuroTrauma Sciences, LLC, Alpharetta, GA 30009, United States of America
| | - Benjamin Buller
- NeuroTrauma Sciences, LLC, Alpharetta, GA 30009, United States of America
| | - Todd A Verdoorn
- NeuroTrauma Sciences, LLC, Alpharetta, GA 30009, United States of America
| | - Clare B Billing
- BioPharmaWorks, LLC, Groton, CT 06340, United States of America
| | - Barclay Morrison
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, United States of America.
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2
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Srinivasan G, Brafman DA. The Emergence of Model Systems to Investigate the Link Between Traumatic Brain Injury and Alzheimer’s Disease. Front Aging Neurosci 2022; 13:813544. [PMID: 35211003 PMCID: PMC8862182 DOI: 10.3389/fnagi.2021.813544] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 12/20/2021] [Indexed: 12/12/2022] Open
Abstract
Numerous epidemiological studies have demonstrated that individuals who have sustained a traumatic brain injury (TBI) have an elevated risk for developing Alzheimer’s disease and Alzheimer’s-related dementias (AD/ADRD). Despite these connections, the underlying mechanisms by which TBI induces AD-related pathology, neuronal dysfunction, and cognitive decline have yet to be elucidated. In this review, we will discuss the various in vivo and in vitro models that are being employed to provide more definite mechanistic relationships between TBI-induced mechanical injury and AD-related phenotypes. In particular, we will highlight the strengths and weaknesses of each of these model systems as it relates to advancing the understanding of the mechanisms that lead to TBI-induced AD onset and progression as well as providing platforms to evaluate potential therapies. Finally, we will discuss how emerging methods including the use of human induced pluripotent stem cell (hiPSC)-derived cultures and genome engineering technologies can be employed to generate better models of TBI-induced AD.
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3
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Pacheco JM, Hines-Lanham A, Stratton C, Mehos CJ, McCurdy KE, Pinkowski NJ, Zhang H, Shuttleworth CW, Morton RA. Spreading Depolarizations Occur in Mild Traumatic Brain Injuries and Are Associated with Postinjury Behavior. eNeuro 2019; 6:ENEURO.0070-19.2019. [PMID: 31748237 PMCID: PMC6893232 DOI: 10.1523/eneuro.0070-19.2019] [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: 02/26/2019] [Revised: 11/06/2019] [Accepted: 11/11/2019] [Indexed: 01/20/2023] Open
Abstract
Millions of people suffer mild traumatic brain injuries (mTBIs) every year, and there is growing evidence that repeated injuries can result in long-term pathology. The acute symptoms of these injuries may or may not include the loss of consciousness but do include disorientation, confusion, and/or the inability to concentrate. Most of these acute symptoms spontaneously resolve within a few hours or days. However, the underlying physiological and cellular mechanisms remain unclear. Spreading depolarizations (SDs) are known to occur in rodents and humans following moderate and severe TBIs, and SDs have long been hypothesized to occur in more mild injuries. Using a closed skull impact model, we investigated the presence of SDs immediately following a mTBI. Animals remained motionless for multiple minutes following an impact and once recovered had fewer episodes of movement. We recorded the defining electrophysiological properties of SDs, including the large extracellular field potential shifts and suppression of high-frequency cortical activity. Impact-induced SDs were also associated with a propagating wave of reduced cerebral blood flow (CBF). In the wake of the SD, there was a prolonged period of reduced CBF that recovered in approximately 90 min. Similar to SDs in more severe injuries, the impact-induced SDs could be blocked with ketamine. Interestingly, impacts at a slower velocity did not produce the prolonged immobility and did not initiate SDs. Our data suggest that SDs play a significant role in mTBIs and SDs may contribute to the acute symptoms of mTBIs.
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Affiliation(s)
- Johann M Pacheco
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM 87131
| | - Ashlyn Hines-Lanham
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM 87131
| | - Claire Stratton
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM 87131
| | - Carissa J Mehos
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM 87131
| | - Kathryn E McCurdy
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM 87131
| | - Natalie J Pinkowski
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM 87131
| | - Haikun Zhang
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM 87131
| | - C William Shuttleworth
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM 87131
| | - Russell A Morton
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM 87131
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4
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Alves JL, Rato J, Silva V. Why Does Brain Trauma Research Fail? World Neurosurg 2019; 130:115-121. [PMID: 31284053 DOI: 10.1016/j.wneu.2019.06.212] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 06/26/2019] [Accepted: 06/27/2019] [Indexed: 02/06/2023]
Abstract
Traumatic brain injury (TBI) represents a major health care problem and a significant social and economic issue worldwide. Considering the generalized failure in introducing effective drugs and clinical protocols, there is an urgent need for efficient treatment modalities, able to improve devastating posttraumatic morbidity and mortality. In this work, the status of brain trauma research is analyzed in all its aspects, including basic and translational science and clinical trials. Implicit and explicit challenges to different lines of research are discussed and clinical trial structures and outcomes are scrutinized, along with possible explanations for systematic therapeutic failures and their implications for future development of drug and clinical trials. Despite significant advances in basic and clinical research in recent years, no specific therapeutic protocols for TBI have been shown to be effective. New potential therapeutic targets have been identified, following a better understanding of pathophysiologic mechanisms underlying TBI, although with disappointing results. Several reasons can be pinpointed at different levels, from inaccurate animal models of disease to faulty preclinical and clinical trials, with poor design and subjective outcome measures. Distinct strategies can be delineated to overcome specific shortcomings of research studies. Identifying and contextualizing the failures that have dominated TBI research is mandatory. This review analyzes current approaches and discusses possible strategies for improving outcomes.
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Affiliation(s)
- José Luís Alves
- Department of Neurosurgery, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal.
| | - Joana Rato
- Department of Neurosurgery, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal
| | - Vitor Silva
- Department of Neurosurgery, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal
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5
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Walker A, Kim J, Wyatt J, Terlouw A, Balachandran K, Wolchok J. Repeated In Vitro Impact Conditioning of Astrocytes Decreases the Expression and Accumulation of Extracellular Matrix. Ann Biomed Eng 2019; 47:967-979. [PMID: 30706307 DOI: 10.1007/s10439-019-02219-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 01/24/2019] [Indexed: 12/19/2022]
Abstract
Pathological changes to the physical and chemical properties of brain extracellular matrix (ECM) occur following injury. It is generally assumed that astrocytes play an important role in these changes. What remain unclear are the triggers that lead to changes in the regulation of ECM by astrocytes following injury. We hypothesize that mechanical stimulation triggers genotypic and phenotypic changes to astrocytes that could ultimately reshape the ECM composition of the central nervous system following injury. To explore astrocyte mechanobiology, an in vitro drop test bioreactor was employed to condition primary rat astrocytes using short duration (10 ms), high deceleration (150G) and strain (20%) impact stimuli. Experiments were designed to explore the effect of single and repeated impact (single vs. double) on mechano-sensitive behavior including cell viability; ECM gene (collagens I and IV, fibronectin, neurocan, versican) and reactivity gene [glial fibrillary acidic protein (GFAP), S100B, vimentin] expression; matrix regulatory cytokine secretion [matrix metalloproteinase 2 (MMP-2), tissue inhibitor of metalloproteinases 1 (TIMP1), transforming growth factor beta 1 (TGFβ1)]; and matrix accumulation [collagen and glycosaminoglycan (GAG)]. Experiments revealed that both ECM and reactive gliosis gene expression was significantly decreased in response to impact conditioning. The decreases for several genes, including collagen, versican, and GFAP were sensitive to impact number, suggesting mechano-sensitivity to repeated impact conditioning. The measured decreases in ECM gene expression were supported by longer-term in vitro experiments that demonstrated significant decreases in chondroitin sulfate proteoglycan (CSPG) and collagen accumulation within impact conditioned 3-D scaffolds accompanied by a 25% decrease in elastic modulus. Overall, the general trend across all samples was towards altered ECM and reactive gliosis gene expression in response to impact. These results suggest that the regulation of ECM production by astrocytes is sensitive to mechanical stimuli, and that repeated impact conditioning may increase this sensitivity.
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Affiliation(s)
- Addison Walker
- Department of Biomedical Engineering, University of Arkansas, 125 Engineering Hall, Fayetteville, AR, 72701, USA
| | - Johntaehwan Kim
- Department of Biomedical Engineering, University of Arkansas, 125 Engineering Hall, Fayetteville, AR, 72701, USA
| | - Joseph Wyatt
- Department of Biomedical Engineering, University of Arkansas, 125 Engineering Hall, Fayetteville, AR, 72701, USA
| | - Abby Terlouw
- Department of Biomedical Engineering, University of Arkansas, 125 Engineering Hall, Fayetteville, AR, 72701, USA
| | - Kartik Balachandran
- Department of Biomedical Engineering, University of Arkansas, 125 Engineering Hall, Fayetteville, AR, 72701, USA
| | - Jeffrey Wolchok
- Department of Biomedical Engineering, University of Arkansas, 125 Engineering Hall, Fayetteville, AR, 72701, USA.
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6
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Phillips JK, Sherman SA, Oungoulian SR, Finan JD. Method for High Speed Stretch Injury of Human Induced Pluripotent Stem Cell-derived Neurons in a 96-well Format. J Vis Exp 2018. [PMID: 29733307 PMCID: PMC6100707 DOI: 10.3791/57305] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Traumatic brain injury (TBI) is a major clinical challenge with high morbidity and mortality. Despite decades of pre-clinical research, no proven therapies for TBI have been developed. This paper presents a novel method for pre-clinical neurotrauma research intended to complement existing pre-clinical models. It introduces human pathophysiology through the use of human induced pluripotent stem cell-derived neurons (hiPSCNs). It achieves loading pulse duration similar to the loading durations of clinical closed head impact injury. It employs a 96-well format that facilitates high throughput experiments and makes efficient use of expensive cells and culture reagents. Silicone membranes are first treated to remove neurotoxic uncured polymer and then bonded to commercial 96-well plate bodies to create stretchable 96-well plates. A custom-built device is used to indent some or all of the well bottoms from beneath, inducing equibiaxial mechanical strain that mechanically injures cells in culture in the wells. The relationship between indentation depth and mechanical strain is determined empirically using high speed videography of well bottoms during indentation. Cells, including hiPSCNs, can be cultured on these silicone membranes using modified versions of conventional cell culture protocols. Fluorescent microscopic images of cell cultures are acquired and analyzed after injury in a semi-automated fashion to quantify the level of injury in each well. The model presented is optimized for hiPSCNs but could in theory be applied to other cell types.
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Affiliation(s)
- Jack K Phillips
- Department of Neurosurgery, NorthShore University HealthSystem
| | - Sydney A Sherman
- Department of Neurosurgery, NorthShore University HealthSystem; Midwestern University/Chicago College of Osteopathic Medicine
| | | | - John D Finan
- Department of Neurosurgery, NorthShore University HealthSystem;
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7
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Effgen GB, Morrison B. Electrophysiological and Pathological Characterization of the Period of Heightened Vulnerability to Repetitive Injury in an in Vitro Stretch Model. J Neurotrauma 2017; 34:914-924. [DOI: 10.1089/neu.2016.4477] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Affiliation(s)
- Gwen B. Effgen
- Department of Biomedical Engineering, Columbia University, New York, New York
| | - Barclay Morrison
- Department of Biomedical Engineering, Columbia University, New York, New York
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8
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Bioorthogonal chemical imaging of metabolic activities in live mammalian hippocampal tissues with stimulated Raman scattering. Sci Rep 2016; 6:39660. [PMID: 28000773 PMCID: PMC5175176 DOI: 10.1038/srep39660] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 11/25/2016] [Indexed: 12/22/2022] Open
Abstract
Brain is an immensely complex system displaying dynamic and heterogeneous metabolic activities. Visualizing cellular metabolism of nucleic acids, proteins, and lipids in brain with chemical specificity has been a long-standing challenge. Recent development in metabolic labeling of small biomolecules allows the study of these metabolisms at the global level. However, these techniques generally require nonphysiological sample preparation for either destructive mass spectrometry imaging or secondary labeling with relatively bulky fluorescent labels. In this study, we have demonstrated bioorthogonal chemical imaging of DNA, RNA, protein and lipid metabolism in live rat brain hippocampal tissues by coupling stimulated Raman scattering microscopy with integrated deuterium and alkyne labeling. Heterogeneous metabolic incorporations for different molecular species and neurogenesis with newly-incorporated DNA were observed in the dentate gyrus of hippocampus at the single cell level. We further applied this platform to study metabolic responses to traumatic brain injury in hippocampal slice cultures, and observed marked upregulation of protein and lipid metabolism particularly in the hilus region of the hippocampus within days of mechanical injury. Thus, our method paves the way for the study of complex metabolic profiles in live brain tissue under both physiological and pathological conditions with single-cell resolution and minimal perturbation.
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9
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Stretch Injury of Human Induced Pluripotent Stem Cell Derived Neurons in a 96 Well Format. Sci Rep 2016; 6:34097. [PMID: 27671211 PMCID: PMC5037451 DOI: 10.1038/srep34097] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 09/07/2016] [Indexed: 01/27/2023] Open
Abstract
Traumatic brain injury (TBI) is a major cause of mortality and morbidity with limited therapeutic options. Traumatic axonal injury (TAI) is an important component of TBI pathology. It is difficult to reproduce TAI in animal models of closed head injury, but in vitro stretch injury models reproduce clinical TAI pathology. Existing in vitro models employ primary rodent neurons or human cancer cell line cells in low throughput formats. This in vitro neuronal stretch injury model employs human induced pluripotent stem cell-derived neurons (hiPSCNs) in a 96 well format. Silicone membranes were attached to 96 well plate tops to create stretchable, culture substrates. A custom-built device was designed and validated to apply repeatable, biofidelic strains and strain rates to these plates. A high content approach was used to measure injury in a hypothesis-free manner. These measurements are shown to provide a sensitive, dose-dependent, multi-modal description of the response to mechanical insult. hiPSCNs transition from healthy to injured phenotype at approximately 35% Lagrangian strain. Continued development of this model may create novel opportunities for drug discovery and exploration of the role of human genotype in TAI pathology.
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10
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Lamprecht MR, Elkin BS, Kesavabhotla K, Crary JF, Hammers JL, Huh JW, Raghupathi R, Morrison B. Strong Correlation of Genome-Wide Expression after Traumatic Brain Injury In Vitro and In Vivo Implicates a Role for SORLA. J Neurotrauma 2016; 34:97-108. [PMID: 26919808 DOI: 10.1089/neu.2015.4306] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The utility of in vitro models of traumatic brain injury (TBI) depends on their ability to recapitulate the in vivo TBI cascade. In this study, we used a genome-wide approach to compare changes in gene expression at several time points post-injury in both an in vitro model and an in vivo model of TBI. We found a total of 2073 differentially expressed genes in our in vitro model and 877 differentially expressed genes in our in vivo model when compared to noninjured controls. We found a strong correlation in gene expression changes between the two models (r = 0.69), providing confidence that the in vitro model represented at least part of the in vivo injury cascade. From these data, we searched for genes with significant changes in expression over time (analysis of covariance) and identified sorting protein-related receptor with A-type repeats (SORLA). SORLA directs amyloid precursor protein to the recycling pathway by direct binding and away from amyloid-beta producing enzymes. Mutations of SORLA have been linked to Alzheimer's disease (AD). We confirmed downregulation of SORLA expression in organotypic hippocampal slice cultures by immunohistochemistry and Western blotting and present preliminary data from human tissue that is consistent with these experimental results. Together, these data suggest that the in vitro model of TBI used in this study strongly recapitulates the in vivo TBI pathobiology and is well suited for future mechanistic or therapeutic studies. The data also suggest the possible involvement of SORLA in the post-traumatic cascade linking TBI to AD.
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Affiliation(s)
- Michael R Lamprecht
- 1 Department of Biomedical Engineering, Columbia University , New York, New York
| | - Benjamin S Elkin
- 1 Department of Biomedical Engineering, Columbia University , New York, New York.,2 MEA Forensic Engineers & Scientists , Mississauga, Ontario, Canada
| | - Kartik Kesavabhotla
- 1 Department of Biomedical Engineering, Columbia University , New York, New York
| | - John F Crary
- 3 Department of Pathology, Fishberg Department of Neuroscience, Friedman Brain Institute , and the Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Jennifer L Hammers
- 4 Office of Chief Medical Examiner , City of New York, New York, New York
| | - Jimmy W Huh
- 5 Department of Anesthesia and Critical Care, Children's Hospital of Philadelphia , Philadelphia, Pennsylvania
| | - Ramesh Raghupathi
- 6 Department of Neurobiology and Anatomy, Drexel University College of Medicine , Philadelphia, Pennsylvania
| | - Barclay Morrison
- 1 Department of Biomedical Engineering, Columbia University , New York, New York
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11
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Vogel EW, Effgen GB, Patel TP, Meaney DF, Bass CRD, Morrison B. Isolated Primary Blast Inhibits Long-Term Potentiation in Organotypic Hippocampal Slice Cultures. J Neurotrauma 2015; 33:652-61. [PMID: 26414012 DOI: 10.1089/neu.2015.4045] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Over the last 13 years, traumatic brain injury (TBI) has affected over 230,000 U.S. service members through the conflicts in Iraq and Afghanistan, mostly as a result of exposure to blast events. Blast-induced TBI (bTBI) is multi-phasic, with the penetrating and inertia-driven phases having been extensively studied. The effects of primary blast injury, caused by the shockwave interacting with the brain, remain unclear. Earlier in vivo studies in mice and rats have reported mixed results for primary blast effects on behavior and memory. Using a previously developed shock tube and in vitro sample receiver, we investigated the effect of isolated primary blast on the electrophysiological function of rat organotypic hippocampal slice cultures (OHSC). We found that pure primary blast exposure inhibited long-term potentiation (LTP), the electrophysiological correlate of memory, with a threshold between 9 and 39 kPa·ms impulse. This deficit occurred well below a previously identified threshold for cell death (184 kPa·ms), supporting our previously published finding that primary blast can cause changes in brain function in the absence of cell death. Other functional measures such as spontaneous activity, network synchronization, stimulus-response curves, and paired-pulse ratios (PPRs) were less affected by primary blast exposure, as compared with LTP. This is the first study to identify a tissue-level tolerance threshold for electrophysiological changes in neuronal function to isolated primary blast.
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Affiliation(s)
- Edward W Vogel
- 1 Department of Biomedical Engineering, Columbia University , New York, New York
| | - Gwen B Effgen
- 1 Department of Biomedical Engineering, Columbia University , New York, New York
| | - Tapan P Patel
- 2 Department of Bioengineering, University of Pennsylvania , Philadelphia, Pennsylvania
| | - David F Meaney
- 2 Department of Bioengineering, University of Pennsylvania , Philadelphia, Pennsylvania
| | - Cameron R Dale Bass
- 3 Department of Biomedical Engineering, Duke University , Durham, North Carolina
| | - Barclay Morrison
- 1 Department of Biomedical Engineering, Columbia University , New York, New York
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12
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A novel perspective on neuron study: damaging and promoting effects in different neurons induced by mechanical stress. Biomech Model Mechanobiol 2015; 15:1019-27. [DOI: 10.1007/s10237-015-0743-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 10/29/2015] [Indexed: 12/11/2022]
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13
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Lamprecht MR, Morrison B. A Combination Therapy of 17β-Estradiol and Memantine Is More Neuroprotective Than Monotherapies in an Organotypic Brain Slice Culture Model of Traumatic Brain Injury. J Neurotrauma 2015; 32:1361-8. [DOI: 10.1089/neu.2015.3912] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Affiliation(s)
| | - Barclay Morrison
- Department of Biomedical Engineering, Columbia University, New York, New York
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14
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Rao W, Zhang L, Peng C, Hui H, Wang K, Su N, Wang L, Dai SH, Yang YF, Chen T, Luo P, Fei Z. Downregulation of STIM2 improves neuronal survival after traumatic brain injury by alleviating calcium overload and mitochondrial dysfunction. Biochim Biophys Acta Mol Basis Dis 2015; 1852:2402-13. [PMID: 26300487 DOI: 10.1016/j.bbadis.2015.08.014] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 07/28/2015] [Accepted: 08/19/2015] [Indexed: 12/30/2022]
Abstract
Although store-operated calcium entry (SOCE) has been implicated in several neurological disorders, the exact mechanism for its role in traumatic brain injury (TBI) has not been elucidated. In this study, we found that TBI upregulated the expression of a calcium sensor protein called stromal interactive molecule 2 (STIM2); however, the levels of its homologue, STIM1, were unaffected. Both STIM1 and STIM2 are crucial components of SOCE, both in vivo and in vitro. Using shRNA, we discovered that downregulation of STIM2, but not STIM1, significantly improved neuronal survival in both an in vitro and in vivo model of TBI, decreasing neuronal apoptosis, and preserving neurological function. This neuroprotection was associated with alleviating TBI-induced calcium overload and preserving mitochondrial function. Additionally, downregulation of STIM2 not only inhibited Ca(2+) release from the endoplasmic reticulum (ER), but also reduced SOCE-mediated Ca(2+) influx, decreased mitochondrial Ca(2+), restored mitochondrial morphology and improved mitochondrial function, including MMP maintenance, ROS production and ATP synthesis. These results indicate that inhibition of STIM2 can protect neurons from TBI by inhibiting calcium overload and preserving mitochondrial function. This suggests that STIM2 might be an effective interventional target for TBI.
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Affiliation(s)
- Wei Rao
- Department of Neurosurgery, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, PR China
| | - Lei Zhang
- Department of Neurosurgery, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, PR China
| | - Cheng Peng
- Department of Neurosurgery, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, PR China
| | - Hao Hui
- Department of Neurosurgery, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, PR China
| | - Kai Wang
- Department of Neurosurgery, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, PR China
| | - Ning Su
- Department of Neurosurgery, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, PR China
| | - Li Wang
- Department of Neurosurgery, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, PR China
| | - Shu-Hui Dai
- Department of Neurosurgery, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, PR China
| | - Yue-Fan Yang
- Department of Neurosurgery, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, PR China
| | - Tao Chen
- Department of Neurosurgery, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, PR China
| | - Peng Luo
- Department of Neurosurgery, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, PR China
| | - Zhou Fei
- Department of Neurosurgery, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, PR China.
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15
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Previtera ML, Firestein BL. Glutamate affects dendritic morphology of neurons grown on compliant substrates. Biotechnol Prog 2015; 31:1128-32. [PMID: 25827105 DOI: 10.1002/btpr.2085] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 03/25/2015] [Indexed: 12/26/2022]
Abstract
Brain stiffness changes in response to injury or disease. As a secondary consequence, glutamate is released from neurons and astroglia. Two types of glutamate receptors, N-methyl-d-aspartate (NMDA) and α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, sense mechanotransduction, leading to downstream signaling in neurons. Recently, our group reported that these two receptors affect dendrite morphology in hippocampal neurons grown on compliant substrates. Blocking receptor activity has distinct effects on dendrites, depending on whether neurons are grown on soft or stiff gels. In the current study, we examine whether exposure to glutamate itself alters stiffness-mediated changes to dendrites in hippocampal neurons. We find that glutamate augments changes seen when neurons are grown on soft gels of 300 or 600 Pa, but in contrast, glutamate attenuates changes seen when neurons are grown on stiff gels of 3,000 Pa. These results suggest that there is interplay between mechanosensing and glutamate receptor activation in determining dendrite morphology in neurons.
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Affiliation(s)
- Michelle L Previtera
- Graduate Program in Molecular Biosciences, the State University of New Jersey, Piscataway, NJ, 08854-8082.,Dept. of Cell Biology and Neuroscience, the State University of New Jersey, Piscataway, NJ, 08854-8082
| | - Bonnie L Firestein
- Dept. of Cell Biology and Neuroscience, the State University of New Jersey, Piscataway, NJ, 08854-8082.,Dept. of Biomedical Engineering, Rutgers, the State University of New Jersey, Piscataway, NJ, 08854-8082
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Predicting changes in cortical electrophysiological function after in vitro traumatic brain injury. Biomech Model Mechanobiol 2015; 14:1033-44. [PMID: 25628144 DOI: 10.1007/s10237-015-0652-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 01/14/2015] [Indexed: 01/09/2023]
Abstract
Finite element (FE) models of traumatic brain injury (TBI) are capable of predicting injury-induced brain tissue deformation. However, current FE models are not equipped to predict the biological consequences of tissue deformation, which requires the determination of tolerance criteria relating the effects of mechanical stimuli to biologically relevant functional responses. To address this deficiency, we present functional tolerance criteria for the cortex for alterations in neuronal network electrophysiological function in response to controlled mechanical stimuli. Organotypic cortical slice cultures were mechanically injured via equibiaxial stretch with a well-characterized in vitro model of TBI at tissue strains and strain rates relevant to TBI (up to Lagrangian strain of 0.59 and strain rates up to 29 [Formula: see text]. At 4-6 days post-injury, electrophysiological function was assessed simultaneously throughout the cortex using microelectrode arrays. Electrophysiological parameters associated with unstimulated spontaneous network activity (neural event rate, duration, and magnitude), stimulated evoked responses (the maximum response [Formula: see text], the stimulus current necessary for a half-maximal response [Formula: see text], and the electrophysiological parameter [Formula: see text] that is representative of firing uniformity), and evoked paired-pulse ratios at varying interstimulus intervals were quantified for each cortical slice culture. Nonlinear regression was performed between mechanical injury parameters as independent variables (tissue strain and strain rate) and each electrophysiological parameter as output. Parsimonious best-fit equations were determined from a large pool of candidate equations with tenfold cross-validation. Changes in electrophysiological parameters were dependent on strain and strain rate in a complex manner. Compared to the hippocampus, the cortex was less spontaneously active, less excitable, and less prone to significant changes in electrophysiological function in response to controlled deformation (strain or strain rate). Our study provides functional data that can be incorporated into FE models to improve their predictive capabilities of the in vivo consequences of TBI.
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Heller Z, Wyatt J, Arnaud A, Wolchok JC. An In Vitro Impact Model for the Study of Central Nervous System Cell Mechanobiology. Cell Mol Bioeng 2014. [DOI: 10.1007/s12195-014-0347-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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18
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Effgen GB, Vogel EW, Lynch KA, Lobel A, Hue CD, Meaney DF, Bass CR“D, Morrison B. Isolated Primary Blast Alters Neuronal Function with Minimal Cell Death in Organotypic Hippocampal Slice Cultures. J Neurotrauma 2014; 31:1202-10. [DOI: 10.1089/neu.2013.3227] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Gwen B. Effgen
- Department of Biomedical Engineering, Columbia University, New York, New York
| | - Edward W. Vogel
- Department of Biomedical Engineering, Columbia University, New York, New York
| | - Kimberly A. Lynch
- Department of Biomedical Engineering, Columbia University, New York, New York
| | - Ayelet Lobel
- Department of Biomedical Engineering, Columbia University, New York, New York
| | - Christopher D. Hue
- Department of Biomedical Engineering, Columbia University, New York, New York
| | - David F. Meaney
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | | | - Barclay Morrison
- Department of Biomedical Engineering, Columbia University, New York, New York
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19
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Lamprecht MR, Morrison B. GPR30 activation is neither necessary nor sufficient for acute neuroprotection by 17β-estradiol after an ischemic injury in organotypic hippocampal slice cultures. Brain Res 2014; 1563:131-7. [DOI: 10.1016/j.brainres.2014.03.037] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 03/04/2014] [Accepted: 03/25/2014] [Indexed: 12/11/2022]
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20
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Meaney DF, Morrison B, Dale Bass C. The mechanics of traumatic brain injury: a review of what we know and what we need to know for reducing its societal burden. J Biomech Eng 2014; 136:021008. [PMID: 24384610 PMCID: PMC4023660 DOI: 10.1115/1.4026364] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 12/20/2013] [Accepted: 12/27/2013] [Indexed: 12/25/2022]
Abstract
Traumatic brain injury (TBI) is a significant public health problem, on pace to become the third leading cause of death worldwide by 2020. Moreover, emerging evidence linking repeated mild traumatic brain injury to long-term neurodegenerative disorders points out that TBI can be both an acute disorder and a chronic disease. We are at an important transition point in our understanding of TBI, as past work has generated significant advances in better protecting us against some forms of moderate and severe TBI. However, we still lack a clear understanding of how to study milder forms of injury, such as concussion, or new forms of TBI that can occur from primary blast loading. In this review, we highlight the major advances made in understanding the biomechanical basis of TBI. We point out opportunities to generate significant new advances in our understanding of TBI biomechanics, especially as it appears across the molecular, cellular, and whole organ scale.
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Affiliation(s)
- David F. Meaney
- Departments of Bioengineeringand Neurosurgery,University of Pennsylvania,Philadelphia, PA 19104-6392e-mail:
| | - Barclay Morrison
- Department of Biomedical Engineering,Columbia University,New York, NY 10027
| | - Cameron Dale Bass
- Department of Biomedical Engineering,Duke University,Durham, NC 27708-0281
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21
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Gurkoff G, Shahlaie K, Lyeth B, Berman R. Voltage-gated calcium channel antagonists and traumatic brain injury. Pharmaceuticals (Basel) 2013; 6:788-812. [PMID: 24276315 PMCID: PMC3816709 DOI: 10.3390/ph6070788] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 06/06/2013] [Accepted: 06/06/2013] [Indexed: 01/17/2023] Open
Abstract
Traumatic brain injury (TBI) is a leading cause of death and disability in the United States. Despite more than 30 years of research, no pharmacological agents have been identified that improve neurological function following TBI. However, several lines of research described in this review provide support for further development of voltage gated calcium channel (VGCC) antagonists as potential therapeutic agents. Following TBI, neurons and astrocytes experience a rapid and sometimes enduring increase in intracellular calcium ([Ca2+]i). These fluxes in [Ca2+]i drive not only apoptotic and necrotic cell death, but also can lead to long-term cell dysfunction in surviving cells. In a limited number of in vitro experiments, both L-type and N-type VGCC antagonists successfully reduced calcium loads as well as neuronal and astrocytic cell death following mechanical injury. In rodent models of TBI, administration of VGCC antagonists reduced cell death and improved cognitive function. It is clear that there is a critical need to find effective therapeutics and rational drug delivery strategies for the management and treatment of TBI, and we believe that further investigation of VGCC antagonists should be pursued before ruling out the possibility of successful translation to the clinic.
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Affiliation(s)
- Gene Gurkoff
- Department of Neurological Surgery, One Shields Avenue, University of California, Davis, CA 95616, USA; E-Mails: (K.S.); (B.L.); (R.B.)
- NSF Center for Biophotonics Science and Technology, Suite 2700 Stockton Blvd, Suite 1400, Sacramento, CA, 95817, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-530-754-7501; Fax: +1-530-754-5125
| | - Kiarash Shahlaie
- Department of Neurological Surgery, One Shields Avenue, University of California, Davis, CA 95616, USA; E-Mails: (K.S.); (B.L.); (R.B.)
| | - Bruce Lyeth
- Department of Neurological Surgery, One Shields Avenue, University of California, Davis, CA 95616, USA; E-Mails: (K.S.); (B.L.); (R.B.)
| | - Robert Berman
- Department of Neurological Surgery, One Shields Avenue, University of California, Davis, CA 95616, USA; E-Mails: (K.S.); (B.L.); (R.B.)
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Dollé JP, Morrison B, Schloss RR, Yarmush ML. An organotypic uniaxial strain model using microfluidics. LAB ON A CHIP 2013; 13:432-42. [PMID: 23233120 PMCID: PMC3546521 DOI: 10.1039/c2lc41063j] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Traumatic brain injuries are the leading cause of disability each year in the US. The most common and devastating consequence is the stretching of axons caused by shear deformation that occurs during rotational acceleration of the brain during injury. The injury effects on axonal molecular and functional events are not fully characterized. We have developed a strain injury model that maintains the three dimensional cell architecture and neuronal networks found in vivo with the ability to visualize individual axons and their response to a mechanical injury. The advantage of this model is that it can apply uniaxial strains to axons that make functional connections between two organotypic slices and injury responses can be observed in real-time and over long term. This uniaxial strain model was designed to be capable of applying an array of mechanical strains at various rates of strain, thus replicating a range of modes of axonal injury. Long term culture, preservation of slice and cell orientation, and slice-slice connection on the device was demonstrated. The device has the ability to strain either individual axons or bundles of axons through the control of microchannel dimensions. The fidelity of the model was verified by observing characteristic responses to various strain injuries which included axonal beading, delayed elastic effects and breakdown in microtubules. Microtubule breakdown was shown to be dependent on the degree of the applied strain field, where maximal breakdown was observed at peak strain and minimal breakdown is observed at low strain. This strain injury model could be a powerful tool in assessing strain injury effects on functional axonal connections.
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Affiliation(s)
- Jean-Pierre Dollé
- Department of Biomedical Engineering, Rutgers, the State University of New Jersey, 599 Taylor Road, Piscataway, New Jersey 08854. Fax: 732-445-3753, Phone: 732-445-4500
| | - Barclay Morrison
- Department of Biomedical Engineering, Columbia University, 351 Engineering Terrace, 1210 Amsterdam Avenue, New York, NY 10027. Fax: 212-854-8725, Phone: 212-854-6277
| | - Rene R. Schloss
- Department of Biomedical Engineering, Rutgers, the State University of New Jersey, 599 Taylor Road, Piscataway, New Jersey 08854. Fax: 732-445-3753, Phone: 732-445-4500
| | - Martin L. Yarmush
- Department of Biomedical Engineering, Rutgers, the State University of New Jersey, 599 Taylor Road, Piscataway, New Jersey 08854. Fax: 732-445-3753, Phone: 732-445-4500
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Dossi E, Heine C, Servettini I, Gullo F, Sygnecka K, Franke H, Illes P, Wanke E. Functional Regeneration of the ex-vivo Reconstructed Mesocorticolimbic Dopaminergic System. Cereb Cortex 2012; 23:2905-22. [DOI: 10.1093/cercor/bhs275] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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24
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Dixon SJ, Lemberg KM, Lamprecht MR, Skouta R, Zaitsev EM, Gleason CE, Patel DN, Bauer AJ, Cantley AM, Yang WS, Morrison B, Stockwell BR. Ferroptosis: an iron-dependent form of nonapoptotic cell death. Cell 2012; 149:1060-72. [PMID: 22632970 DOI: 10.1016/j.cell.2012.03.042] [Citation(s) in RCA: 8838] [Impact Index Per Article: 736.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Revised: 03/09/2012] [Accepted: 03/13/2012] [Indexed: 02/06/2023]
Abstract
Nonapoptotic forms of cell death may facilitate the selective elimination of some tumor cells or be activated in specific pathological states. The oncogenic RAS-selective lethal small molecule erastin triggers a unique iron-dependent form of nonapoptotic cell death that we term ferroptosis. Ferroptosis is dependent upon intracellular iron, but not other metals, and is morphologically, biochemically, and genetically distinct from apoptosis, necrosis, and autophagy. We identify the small molecule ferrostatin-1 as a potent inhibitor of ferroptosis in cancer cells and glutamate-induced cell death in organotypic rat brain slices, suggesting similarities between these two processes. Indeed, erastin, like glutamate, inhibits cystine uptake by the cystine/glutamate antiporter (system x(c)(-)), creating a void in the antioxidant defenses of the cell and ultimately leading to iron-dependent, oxidative death. Thus, activation of ferroptosis results in the nonapoptotic destruction of certain cancer cells, whereas inhibition of this process may protect organisms from neurodegeneration.
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Affiliation(s)
- Scott J Dixon
- Department of Biological Sciences, Columbia University, 550 West 120th Street, Northwest Corner Building, MC 4846, New York, NY 10027, USA
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25
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Moderate traumatic brain injury triggers rapid necrotic death of immature neurons in the hippocampus. J Neuropathol Exp Neurol 2012; 71:348-59. [PMID: 22437344 DOI: 10.1097/nen.0b013e31824ea078] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Traumatic brain injury (TBI) causes cell death predominantly in the cerebral cortex, but there is additional secondary cell death in the hippocampus. We previously found that most of the dying cells in the mouse hippocampus are newborn immature granular neurons in a mouse model of lateral controlled cortical impact (CCI) injury with a moderate level of impact. It is not known how long this selective cell death in the hippocampal dentate gyrus lasts, and how it is induced. Using Fluoro-Jade B and immunohistochemistry, we show that most of the neuron death in the hippocampus occurs within 24 hours after TBI and that cell death continues at low level for at least another 2 weeks in this lateral CCI model. Most of the dying immature granular neurons did not exhibit morphologic characteristics of apoptosis, and only a small subpopulation of the dying cells was positive for apoptotic markers. In contrast, most of the dying cells coexpressed the receptor-interacting protein 1, a marker of necrosis, suggesting that immature neurons mainly died of necrosis. These results indicate that moderate TBI mainly triggers rapid necrotic death of immature neurons in the hippocampus in a mouse CCI model.
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Abstract
In vitro models of traumatic brain injury (TBI) are helping elucidate the pathobiological mechanisms responsible for dysfunction and delayed cell death after mechanical stimulation of the brain. Researchers have identified compounds that have the potential to break the chain of molecular events set in motion by traumatic injury. Ultimately, the utility of in vitro models in identifying novel therapeutics will be determined by how closely the in vitro cascades recapitulate the sequence of cellular events that play out in vivo after TBI. Herein, the major in vitro models are reviewed, and a discussion of the physical injury mechanisms and culture preparations is employed. A comparison between the efficacy of compounds tested in vitro and in vivo is presented as a critical evaluation of the fidelity of in vitro models to the complex pathobiology that is TBI. We conclude that in vitro models were greater than 88% predictive of in vivo results.
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Affiliation(s)
- Barclay Morrison
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA.
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Effgen GB, Hue CD, Vogel E, Panzer MB, Meaney DF, Bass CR, Morrison B. A Multiscale Approach to Blast Neurotrauma Modeling: Part II: Methodology for Inducing Blast Injury to in vitro Models. Front Neurol 2012; 3:23. [PMID: 22375134 PMCID: PMC3285773 DOI: 10.3389/fneur.2012.00023] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Accepted: 02/07/2012] [Indexed: 01/09/2023] Open
Abstract
Due to the prominent role of improvised explosive devices (IEDs) in wounding patterns of U.S. war-fighters in Iraq and Afghanistan, blast injury has risen to a new level of importance and is recognized to be a major cause of injuries to the brain. However, an injury risk-function for microscopic, macroscopic, behavioral, and neurological deficits has yet to be defined. While operational blast injuries can be very complex and thus difficult to analyze, a simplified blast injury model would facilitate studies correlating biological outcomes with blast biomechanics to define tolerance criteria. Blast-induced traumatic brain injury (bTBI) results from the translation of a shock wave in-air, such as that produced by an IED, into a pressure wave within the skull-brain complex. Our blast injury methodology recapitulates this phenomenon in vitro, allowing for control of the injury biomechanics via a compressed-gas shock tube used in conjunction with a custom-designed, fluid-filled receiver that contains the living culture. The receiver converts the air shock wave into a fast-rising pressure transient with minimal reflections, mimicking the intracranial pressure history in blast. We have developed an organotypic hippocampal slice culture model that exhibits cell death when exposed to a 530 ± 17.7-kPa peak overpressure with a 1.026 ± 0.017-ms duration and 190 ± 10.7 kPa-ms impulse in-air. We have also injured a simplified in vitro model of the blood-brain barrier, which exhibits disrupted integrity immediately following exposure to 581 ± 10.0 kPa peak overpressure with a 1.067 ± 0.006-ms duration and 222 ± 6.9 kPa-ms impulse in-air. To better prevent and treat bTBI, both the initiating biomechanics and the ensuing pathobiology must be understood in greater detail. A well-characterized, in vitro model of bTBI, in conjunction with animal models, will be a powerful tool for developing strategies to mitigate the risks of bTBI.
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Affiliation(s)
- Gwen B Effgen
- Department of Biomedical Engineering, Columbia University New York, NY, USA
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28
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Staal JA, Alexander SR, Liu Y, Dickson TD, Vickers JC. Characterization of cortical neuronal and glial alterations during culture of organotypic whole brain slices from neonatal and mature mice. PLoS One 2011; 6:e22040. [PMID: 21789209 PMCID: PMC3137607 DOI: 10.1371/journal.pone.0022040] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Accepted: 06/14/2011] [Indexed: 01/19/2023] Open
Abstract
Background Organotypic brain slice culturing techniques are extensively used in a wide range of experimental procedures and are particularly useful in providing mechanistic insights into neurological disorders or injury. The cellular and morphological alterations associated with hippocampal brain slice cultures has been well established, however, the neuronal response of mouse cortical neurons to culture is not well documented. Methods In the current study, we compared the cell viability, as well as phenotypic and protein expression changes in cortical neurons, in whole brain slice cultures from mouse neonates (P4–6), adolescent animals (P25–28) and mature adults (P50+). Cultures were prepared using the membrane interface method. Results Propidium iodide labeling of nuclei (due to compromised cell membrane) and AlamarBlue™ (cell respiration) analysis demonstrated that neonatal tissue was significantly less vulnerable to long-term culture in comparison to the more mature brain tissues. Cultures from P6 animals showed a significant increase in the expression of synaptic markers and a decrease in growth-associated proteins over the entire culture period. However, morphological analysis of organotypic brain slices cultured from neonatal tissue demonstrated that there were substantial changes to neuronal and glial organization within the neocortex, with a distinct loss of cytoarchitectural stratification and increased GFAP expression (p<0.05). Additionally, cultures from neonatal tissue had no glial limitans and, after 14 DIV, displayed substantial cellular protrusions from slice edges, including cells that expressed both glial and neuronal markers. Conclusion In summary, we present a substantial evaluation of the viability and morphological changes that occur in the neocortex of whole brain tissue cultures, from different ages, over an extended period of culture.
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Affiliation(s)
- Jerome A Staal
- Menzies Research Institute, University of Tasmania, Hobart, Tasmania, Australia
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29
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Kutzing MK, Luo V, Firestein BL. Measurement of synchronous activity by microelectrode arrays uncovers differential effects of sublethal and lethal glutamate concentrations on cortical neurons. Ann Biomed Eng 2011; 39:2252-62. [PMID: 21544673 DOI: 10.1007/s10439-011-0319-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 04/25/2011] [Indexed: 10/18/2022]
Abstract
We grew cultures of rat cortical cells on microelectrode arrays to investigate the effects of glutamate-mediated neurotoxicity as a model of traumatic brain injury. Treatment with two different concentrations of glutamate, 175 and 250 μM, led to different outcomes. Cultures treated with 250 μM glutamate suffered a loss in overall activity that was not seen in cultures treated with 175 μM glutamate. An analysis of the changes in the synchronization of action potential firing between electrodes, however, revealed a loss of synchronization in subsets of electrode pairs treated with both the higher and lower concentrations of glutamate. We found that this loss of action potential synchronization was dependent on the initial amount of synchronization prior to injury. Finally, our data suggest that the synchronization of electrical activity as well as the susceptibility to loss of firing synchrony is independent of the distance between neurons in a network.
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Affiliation(s)
- Melinda K Kutzing
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854-8082, USA
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30
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Mazzone GL, Nistri A. Electrochemical detection of endogenous glutamate release from rat spinal cord organotypic slices as a real-time method to monitor excitotoxicity. J Neurosci Methods 2011; 197:128-32. [DOI: 10.1016/j.jneumeth.2011.01.033] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 01/27/2011] [Accepted: 01/28/2011] [Indexed: 01/28/2023]
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31
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Mazzone GL, Nistri A. Effect of the PARP-1 Inhibitor PJ 34 on Excitotoxic Damage Evoked by Kainate on Rat Spinal Cord Organotypic Slices. Cell Mol Neurobiol 2010; 31:469-78. [DOI: 10.1007/s10571-010-9640-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Accepted: 12/13/2010] [Indexed: 12/20/2022]
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Yu Z, Graudejus O, Tsay C, Lacour SP, Wagner S, Morrison B. Monitoring hippocampus electrical activity in vitro on an elastically deformable microelectrode array. J Neurotrauma 2010; 26:1135-45. [PMID: 19594385 DOI: 10.1089/neu.2008.0810] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Interfacing electronics and recording electrophysiological activity in mechanically active biological tissues is challenging. This challenge extends to recording neural function of brain tissue in the setting of traumatic brain injury (TBI), which is caused by rapid (within hundreds of milliseconds) and large (greater than 5% strain) brain deformation. Interfacing electrodes must be biocompatible on multiple levels and should deform with the tissue to prevent additional mechanical damage. We describe an elastically stretchable microelectrode array (SMEA) that is capable of undergoing large, biaxial, 2-D stretch while remaining functional. The new SMEA consists of elastically stretchable thin metal films on a silicone membrane. It can stimulate and detect electrical activity from cultured brain tissue (hippocampal slices), before, during, and after large biaxial deformation. We have incorporated the SMEA into a well-characterized in vitro TBI research platform, which reproduces the biomechanics of TBI by stretching the SMEA and the adherent brain slice culture. Mechanical injury parameters, such as strain and strain rate, can be precisely controlled to generate specific levels of damage. The SMEA allowed for quantification of neuronal function both before and after injury, without breaking culture sterility or repositioning the electrodes for the injury event, thus enabling serial and long-term measurements. We report tests of the SMEA and an initial application to study the effect of mechanical stimuli on neuron function, which could be employed as a high-content, drug-screening platform for TBI.
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Affiliation(s)
- Zhe Yu
- Department of Biomedical Engineering, Columbia University, New York, New York 10027, USA
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33
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Ring A, Tanso R, Noraberg J. The use of Organotypic Hippocampal Slice Cultures to Evaluate Protection by Non-competitive NMDA Receptor Antagonists against Excitotoxicity. Altern Lab Anim 2010; 38:71-82. [DOI: 10.1177/026119291003800108] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
There is great interest in testing neuroprotectants which inhibit the neurodegeneration that results from excessive activation of N-methyl-D-aspartate (NMDA) receptors. As an alternative to in vivo testing in animal models, we demonstrate here the use of a complex in vitro model to compare the efficacy and toxicity of NMDA receptor inhibitors. Organotypic hippocampal slice cultures were used to compare the effectiveness of the Alzheimer's disease drug, memantine, the Parkinson's disease drug, procyclidine, and the novel neuroprotectant, gacyclidine (GK11), against NMDA-induced toxicity. All three drugs are non-competitive NMDA receptor open-channel blockers that inhibit excitotoxic injury, and their neuroprotective capacities have been extensively investigated in vivo in animal models. They have also been evaluated as potential countermeasure agents against organophosphate poisoning. Quantitative densitometric image analysis of propidium iodide uptake in hippocampal regions CA1, CA3 and DG, showed that, after exposure to 10μM NMDA for 24 hours, GK11 was the most potent of the three drugs, with an IC50 of about 50nM and complete protection at 250nM. When applied at high doses, GK11 was still the more potent neuroprotectant, and also the least cytotoxic. These findings are consistent with those from in vivo tests in rodents. We conclude that the slice culture model provides valuable pre-clinical data, and that applying the model to the screening of neuroprotectants might significantly limit the use of in vivo tests in animals.
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Affiliation(s)
- Avi Ring
- Department of Protection, Norwegian Defence Research Establishment, Kjeller, Norway
| | - Rita Tanso
- Department of Protection, Norwegian Defence Research Establishment, Kjeller, Norway
| | - Jens Noraberg
- Department of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
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Selective vulnerability of hippocampal cornu ammonis 1 pyramidal cells to excitotoxic insult is associated with the expression of polyamine-sensitive N-methyl-D-asparate-type glutamate receptors. Neuroscience 2010; 165:525-34. [PMID: 19837138 DOI: 10.1016/j.neuroscience.2009.10.018] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2009] [Revised: 10/08/2009] [Accepted: 10/09/2009] [Indexed: 12/30/2022]
Abstract
Excess glutamate release and stimulation of post-synaptic glutamatergic receptors have been implicated in the pathophysiology of many neurological diseases. The hippocampus, and the pyramidal cell layer of the cornu ammonus 1 (CA1) region in particular, has been noted for its selective sensitivity to excitotoxic insults. The current studies examined the role of N-methyl-D-aspartate (NMDA) receptor subunit composition and sensitivity to stimulatory effects of the polyamine spermidine, an allosteric modulator of NMDA NR2 subunit activity, in hippocampal CA1 region sensitivity to excitotoxic insult. Organotypic hippocampal slice cultures of 8 day-old neonatal rat were obtained and maintained in vitro for 5 days. At this time, immunohistochemical analysis of mature neuron density (NeuN); microtubule associated protein-2(a,b) density (MAP-2); and NMDA receptor NR1 and NR2B subunit density in the primary cell layers of the dentate gyrus (DG), CA3, and CA1 regions, was conducted. Further, autoradiographic analysis of NMDA receptor distribution and density (i.e. [(125)I]MK-801 binding) and spermidine (100 microM)-potentiated [(125)I]MK-801 binding in the primary cell layers of these regions was examined. A final series of studies examined effects of prolonged exposure to NMDA (0.1-10 microM) on neurodegeneration in the primary cell layers of the DG, CA3, and CA1 regions, in the absence and presence of spermidine (100 microM) or ifenprodil (100 microM), an allosteric inhibitor of NR2B polypeptide subunit activity. The pyramidal cell layer of the CA1 region demonstrated significantly greater density of mature neurons, MAP-2, NR1 and NR2B subunits, and [(125)I]MK-801 binding than the CA3 region or DG. Twenty-four hour NMDA (10 microM) exposure produced marked neurodegeneration (approximately 350% of control cultures) in the CA1 pyramidal cell region that was significantly reduced by co-exposure to ifenprodil or DL-2-Amino-5-phosphonopentanoic acid (APV). The addition of spermidine significantly potentiated [(125)I]MK-801 binding and neurodegeneration induced by exposure to a non-toxic concentration of NMDA, exclusively in the CA1 region. This neurodegeneration was markedly reduced with co-exposure to ifenprodil. These data suggest that selective sensitivity of the CA1 region to excitotoxic stimuli may be attributable to the density of mature neurons expressing polyamine-sensitive NR2B polypeptide subunits.
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Yu Z, Morrison B. Experimental mild traumatic brain injury induces functional alteration of the developing hippocampus. J Neurophysiol 2009; 103:499-510. [PMID: 19923245 DOI: 10.1152/jn.00775.2009] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It is estimated that approximately 1.5 million Americans suffer a traumatic brain injury (TBI) every year, of which approximately 80% are considered mild injuries. Because symptoms caused by mild TBI last less than half an hour by definition and apparently resolve without treatment, the study of mild TBI is often neglected resulting in a significant knowledge gap for this wide-spread problem. In this work, we studied functional (electrophysiological) alterations of the neonatal/juvenile hippocampus after experimental mild TBI. Our previous work reported significant cell death after in vitro injury >10% biaxial deformation. Here we report that biaxial deformation as low as 5% affected neuronal function during the first week after in vitro mild injury of hippocampal slice cultures. These results suggest that even very mild mechanical events may lead to a quantifiable neuronal network dysfunction. Furthermore, our results highlight that safe limits of mechanical deformation or tolerance criteria may be specific to a particular outcome measure and that neuronal function is a more sensitive measure of injury than cell death. In addition, the age of the tissue at injury was found to be an important factor affecting posttraumatic deficits in electrophysiological function, indicating a relationship between developmental status and vulnerability to mild injury. Our findings suggest that mild pediatric TBI could result in functional deficits that are more serious than currently appreciated.
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Affiliation(s)
- Zhe Yu
- Department of Biomedical Engineering, Columbia University, 1210 Amsterdam Ave., 351 Engineering Terrace, New York, NY 10027, USA
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Chen YC, Smith DH, Meaney DF. In-vitro approaches for studying blast-induced traumatic brain injury. J Neurotrauma 2009; 26:861-76. [PMID: 19397424 DOI: 10.1089/neu.2008.0645] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Traumatic brain injury caused by explosive or blast events is currently divided into four phases: primary, secondary, tertiary, and quaternary blast injury. These phases of blast-induced traumatic brain injury (bTBI) are biomechanically distinct, and can be modeled in both in-vivo and in-vitro systems. The purpose of this review is to consider the mechanical phases of bTBI, how these phases are reproduced with in-vitro models, and to review findings from these models to assess how each phase of bTBI can be examined in more detail. Highlighted are some important gaps in the literature that may be addressed in the future to better identify the exact contributing mechanisms for bTBI. These in-vitro models, viewed in combination with in-vivo models and clinical studies, can be used to assess both the mechanisms and possible treatments for this type of trauma.
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Affiliation(s)
- Yung Chia Chen
- Departments of Bioengineering, University of Pennsylvania, 210 S. 33rd Street, Philadelphia, PA 19104, USA
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37
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Spaethling JM, Klein DM, Singh P, Meaney DF. Calcium-permeable AMPA receptors appear in cortical neurons after traumatic mechanical injury and contribute to neuronal fate. J Neurotrauma 2009; 25:1207-16. [PMID: 18986222 DOI: 10.1089/neu.2008.0532] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Traumatic brain injury (TBI) is one of the most disabling injuries in the population, with 1.5 million Americans new cases each year and 5.3 million Americans overall requiring long-term daily care as a result of their injuries. One critical aspect in developing effective treatments for TBI is determining if new, specific receptor populations emerge in the early phase after injury that can subsequently be targeted to reduce neuronal death after injury. One specific glutamate receptor subtype, the calcium-permeable AMPA receptor (CP-AMPAR), is becoming increasingly recognized for its role in physiological and pathophysiological processes. Although present in relatively low levels in the mature brain, recent studies show that CP-AMPARs can appear following ischemic brain injury or status epilepticus, and the mechanisms that regulate the appearance of these receptors include alterations in transcription, RNA editing, and receptor trafficking. In this report, we use an in vitro model of TBI to show a gradual appearance of CP-AMPARs four hours following injury to cortical neurons. Moreover, the appearance of these receptors is mediated by the phosphorylation of CaMKIIalpha following injury. Selectively blocking CP-AMPARs after mechanical injury leads to a significant reduction in the cell death that occurs 24 h following injury in untreated controls, and is similar in protection offered by broad-spectrum NMDA and AMPA receptor antagonists. These data point to a potentially new and more targeted therapeutic approach for treating TBI.
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Affiliation(s)
- Jennifer M Spaethling
- Department of Pharmacology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6321, USA
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38
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Meacham KW, Giuly RJ, Guo L, Hochman S, DeWeerth SP. A lithographically-patterned, elastic multi-electrode array for surface stimulation of the spinal cord. Biomed Microdevices 2008; 10:259-69. [PMID: 17914674 PMCID: PMC2573864 DOI: 10.1007/s10544-007-9132-9] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
A new, scalable process for microfabrication of a silicone-based, elastic multi-electrode array (MEA) is presented. The device is constructed by spinning poly(dimethylsiloxane) (PDMS) silicone elastomer onto a glass slide, depositing and patterning gold to construct wires and electrodes, spinning on a second PDMS layer, and then micropatterning the second PDMS layer to expose electrode contacts. The micropatterning of PDMS involves a custom reactive ion etch (RIE) process that preserves the underlying gold thin film. Once completed, the device can be removed from the glass slide for conformal interfacing with neural tissue. Prototype MEAs feature electrodes smaller than those known to be reported on silicone substrate (60 microm diameter exposed electrode area) and were capable of selectively stimulating the surface of the in vitro isolated spinal cord of the juvenile rat. Stretchable serpentine traces were also incorporated into the functional PDMS-based MEA, and their implementation and testing is described.
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Affiliation(s)
- Kathleen W Meacham
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 313 Ferst Drive, Atlanta, GA 30332, USA
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Elkin BS, Morrison B. Region-specific tolerance criteria for the living brain. STAPP CAR CRASH JOURNAL 2007; 51:127-138. [PMID: 18278594 DOI: 10.4271/2007-22-0005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Computational models of traumatic brain injury (TBI) can predict injury-induced brain deformation. However, predicting the biological consequences (i.e. cell death or dysfunction) of induced brain deformation requires tolerance criteria. Here, we present a tolerance criterion for the cortex which exhibits important differences from that of the hippocampus. Organotypic slice cultures of the rat cortex, which maintain tissue architecture and cell content consistent with that in vivo, were mechanically injured with an in vitro model described previously. Cultures were stretched equibiaxially up to 0.35 Lagrangian strain at strain rates up to 50 s(-1). Cell death was quantified at 1, 2, 3, and 4 days following injury. Statistical analysis (repeated measures ANOVA) showed that all three factors (Strain, Strain Rate, and Time post-injury) significantly affected cell death. An equation describing cell death as a function of the significant parameters was then fit to the data. Compared to the hippocampus, the cortex was less vulnerable to stretch-induced injury and demonstrated a strain threshold below 0.20. Strain rate was also a significant factor for cortical but not hippocampal cell death. Cortical cell death began at an earlier time point than in the hippocampus, with cell death evident at 1 day post-injury versus 3 days in the hippocampus. In conclusion, different regions of the brain respond differently to identical mechanical stimuli, and this difference should be incorporated into finite element models of TBI if they are to more accurately predict in vivo consequences of TBI.
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Affiliation(s)
- Benjamin S Elkin
- Department of Biomedical Engineering, Columbia University, 351 Engineering Terrace, 1210 Amsterdam Ave., New York, NY, USA
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Montero M, Nielsen M, Rønn LCB, Møller A, Noraberg J, Zimmer J. Neuroprotective effects of the AMPA antagonist PNQX in oxygen-glucose deprivation in mouse hippocampal slice cultures and global cerebral ischemia in gerbils. Brain Res 2007; 1177:124-35. [PMID: 17894933 DOI: 10.1016/j.brainres.2007.08.038] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Revised: 08/08/2007] [Accepted: 08/10/2007] [Indexed: 11/17/2022]
Abstract
PNQX (9-methyl-amino-6-nitro-hexahydro-benzo(F)quinoxalinedione) is a selective AMPA antagonist with demonstrated neuroprotective effects in focal ischemia in rats. Here we report corresponding effects in mouse hippocampal slice cultures subjected to oxygen and glucose deprivation (OGD) and in transient global cerebral ischemia in gerbils. For in vitro studies, hippocampal slice cultures derived from 7-day-old mice and grown for 14 days, were submersed in oxygen-glucose deprived medium for 30 min and exposed to PNQX for 24 h, starting together with OGD, immediately after OGD, or 2 h after OGD. For comparison, other cultures were exposed to the NMDA antagonist MK-801 using the same protocol. Both PNQX and MK-801 displayed significant neuroprotective effects in all hippocampal subfields when present during and after OGD. When added just after OGD, only PNQX retained some neuroprotective effect. When added 2 h after OGD neither PNQX nor MK-801 had an effect. Transient global cerebral ischemia was induced in Mongolian gerbils by occlusion of both common carotid arteries for 4.5 min, with PNQX (10 mg/kg) being injected i.p. 30, 60 and 90 min after the insult. Subsequent analysis of brain sections stained for the neurodegeneration marker Fluoro-Jade B and immunostained for the astroglial marker glial fibrillary acidic protein revealed a significant PNQX-induced decrease in neuronal cell death and astroglial activation. We conclude that, PNQX provided neuroprotection against both global cerebral ischemia in gerbils in vivo and oxygen-glucose deprivation in mouse hippocampal slice cultures.
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Affiliation(s)
- Maria Montero
- Anatomy and Neurobiology, Institute of Medical Biology, University of Southern Denmark, Winslowparken 21st, DK-5000 Odense C, Denmark.
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Elkin BS, Azeloglu EU, Costa KD, Morrison B. Mechanical heterogeneity of the rat hippocampus measured by atomic force microscope indentation. J Neurotrauma 2007; 24:812-22. [PMID: 17518536 DOI: 10.1089/neu.2006.0169] [Citation(s) in RCA: 205] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Knowledge of brain tissue mechanical properties may be critical for formulating hypotheses about traumatic brain injury (TBI) mechanisms and for accurate TBI simulations. To determine the local mechanical properties of anatomical subregions within the rat hippocampus, the atomic force microscope (AFM) was adapted for use on living brain tissue. The AFM provided advantages over alternative methods for measuring local mechanical properties of brain because of its high spatial resolution, high sensitivity, and ability to measure live samples under physiologic conditions. From AFM indentations, a mean pointwise or depth-dependent apparent elastic modulus, E, was determined for the following hippocampal subregions: CA1 pyramidal cell layer (CA1P) and stratum radiatum (CA1SR), CA3 pyramidal cell layer (CA3P) and stratum radiatum (CA3SR), and the dentate gyrus (DG). For all regions, E was indentation-depth-dependent, reflecting the nonlinearity of brain tissue. At an indentation depth of 3microm, E was 234 +/- 152 Pa for CA3P, 308 +/- 184 Pa for CA3SR, 137 +/- 97 Pa for CA1P, 169 +/- 52 Pa for CA1SR, and 201 +/- 133 Pa for DG (mean +/- SD). Our results demonstrate for the first time that the hippocampus is mechanically heterogeneous. Based on our findings, we discuss hypotheses accounting for experimentally observed patterns of hippocampal cell death, which can be tested with biofidelic finite element models of TBI.
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Affiliation(s)
- Benjamin S Elkin
- Department of Biomedical Engineering, Columbia University, New York, New York 10027, USA
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