151
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Abstract
A range of passive and active devices are under development or are already in clinical use to partially restore function after spinal cord injury (SCI). Prosthetic devices to promote host tissue regeneration and plasticity and reconnection are under development, comprising bioengineered bridging materials free of cells. Alternatively, artificial electrical stimulation and robotic bridges may be used, which is our focus here. A range of neuroprostheses interfacing either with CNS or peripheral nervous system both above and below the lesion are under investigation and are at different stages of development or translation to the clinic. In addition, there are orthotic and robotic devices which are being developed and tested in the laboratory and clinic that can provide mechanical assistance, training or substitution after SCI. The range of different approaches used draw on many different aspects of our current but limited understanding of neural regeneration and plasticity, and spinal cord function and interactions with the cortex. The best therapeutic practice will ultimately likely depend on combinations of these approaches and technologies and on balancing the combined effects of these on the biological mechanisms and their interactions after injury. An increased understanding of plasticity of brain and spinal cord, and of the behavior of innate modular mechanisms in intact and injured systems, will likely assist in future developments. We review the range of device designs under development and in use, the basic understanding of spinal cord organization and plasticity, the problems and design issues in device interactions with the nervous system, and the possible benefits of active motor devices.
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Affiliation(s)
- Simon F Giszter
- Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129, USA.
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152
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Okada S, Nakamura M, Renault-Mihara F, Mukaino M, Saiwai H, Toyama Y, Iwamoto Y, Okano H. The role of cytokine signaling in pathophysiology for spinal cord injury. Inflamm Regen 2008. [DOI: 10.2492/inflammregen.28.440] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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153
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Deng Y, Liu Y, Zhu W, Bi X, Wang Y, Ye M, Zhou GQ. The co-transplantation of human bone marrow stromal cells and embryo olfactory ensheathing cells as a new approach to treat spinal cord injury in a rat model. Cytotherapy 2008; 10:551-64. [DOI: 10.1080/14653240802165673] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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154
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Sandrow HR, Shumsky JS, Amin A, Houle JD. Aspiration of a cervical spinal contusion injury in preparation for delayed peripheral nerve grafting does not impair forelimb behavior or axon regeneration. Exp Neurol 2007; 210:489-500. [PMID: 18295206 DOI: 10.1016/j.expneurol.2007.11.029] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Revised: 11/21/2007] [Accepted: 11/26/2007] [Indexed: 01/17/2023]
Abstract
A peripheral nerve graft model was used to examine axonal growth after a unilateral cervical (C) contusion injury in adult rats and to determine if manipulation of an injury site prior to transplantation affects spontaneous behavioral recovery. After a short delay (7 d) the epicenter of a C4 contusion was exposed and aspirated without harming the cavity walls followed by apposition with one end of a pre-degenerated tibial nerve to the rostral cavity wall. After a longer delay (28 d) the aspirated cavity was treated with GDNF to promote regeneration by chronically injured neurons. In both groups forelimb and hindlimb locomotor scores decreased significantly 2 d after lesion site manipulation, but by 7 d, the forelimb score was not different from the pre-manipulation score. There was no significant difference in grid walking or grip strength scores for the affected forelimb in either group 7 d after contusion vs. 7 d after manipulation. Over 1500 brain stem and propriospinal neurons grew axons into the graft with either delay. These results demonstrate that a contusion injury site can be manipulated prior to transplantation without causing long-lasting forelimb or hindlimb behavioral deficits and that peripheral nerve grafts support axonal growth after acute or chronic contusion injury.
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Affiliation(s)
- Harra R Sandrow
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19129, USA
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155
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García-Alías G, Lin R, Akrimi SF, Story D, Bradbury EJ, Fawcett JW. Therapeutic time window for the application of chondroitinase ABC after spinal cord injury. Exp Neurol 2007; 210:331-8. [PMID: 18158149 DOI: 10.1016/j.expneurol.2007.11.002] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2007] [Revised: 11/08/2007] [Accepted: 11/08/2007] [Indexed: 11/17/2022]
Abstract
Rats with a crush in the dorsal funiculi of the C4 segment of the spinal cord were treated with chondroitinase ABC delivered to the lateral ventricle, receiving 6 intraventricular injections on alternate days. In order to investigate the time window of efficacy of chondroitinase, treatment was begun at the time of injury or after a 2, 4 or 7 days delay. Behavioural testing over 6 weeks showed that acutely treated animals showed improved skilled forelimb reaching compared to penicillinase controls. Forelimb contact placing recovered in treated animals but not controls, and gait analysis showed recovery towards normal forelimb stride length in treated animals but not controls. Chondroitinase-treated animals showed greater axon regeneration than controls. The treatment effect on contact placing, stride length and axon regeneration was not dependent on the timing of the start of treatment, but in skilled paw reaching acutely treated animals recovered better function. The area of chondroitinase ABC digestion visualized by stub antibody staining included widespread digestion around the lateral ventricles and partial digestion of cervical spinal cord white matter, but not grey matter.
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Affiliation(s)
- Guillermo García-Alías
- Centre for Brain Repair, Department of Clinical Neuroscience, University of Cambridge, Cambridge CB2 0PY, UK
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156
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Biernaskie J, Sparling JS, Liu J, Shannon CP, Plemel JR, Xie Y, Miller FD, Tetzlaff W. Skin-derived precursors generate myelinating Schwann cells that promote remyelination and functional recovery after contusion spinal cord injury. J Neurosci 2007; 27:9545-59. [PMID: 17804616 PMCID: PMC6672973 DOI: 10.1523/jneurosci.1930-07.2007] [Citation(s) in RCA: 222] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Transplantation of exogenous cells is one approach to spinal cord repair that could potentially enhance the growth and myelination of endogenous axons. Here, we asked whether skin-derived precursors (SKPs), a neural crest-like precursor that can be isolated and expanded from mammalian skin, could be used to repair the injured rat spinal cord. To ask this question, we isolated and expanded genetically tagged murine SKPs and either transplanted them directly into the contused rat spinal cord or differentiated them into Schwann cells (SCs), and performed similar transplantations with the isolated, expanded SKP-derived SCs. Neuroanatomical analysis of these transplants 12 weeks after transplantation revealed that both cell types survived well within the injured spinal cord, reduced the size of the contusion cavity, myelinated endogenous host axons, and recruited endogenous SCs into the injured cord. However, SKP-derived SCs also provided a bridge across the lesion site, increased the size of the spared tissue rim, myelinated spared axons within the tissue rim, reduced reactive gliosis, and provided an environment that was highly conducive to axonal growth. Importantly, SKP-derived SCs provided enhanced locomotor recovery relative to both SKPs and forebrain subventricular zone neurospheres, and had no impact on mechanical or heat sensitivity thresholds. Thus, SKP-derived SCs provide an accessible, potentially autologous source of cells for transplantation into and treatment of the injured spinal cord.
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Affiliation(s)
- Jeff Biernaskie
- Developmental and Stem Cell Biology Group, Hospital for Sick Children, and
| | - Joseph S. Sparling
- International Collaboration on Repair Discoveries, and
- Departments of Zoology and
| | - Jie Liu
- International Collaboration on Repair Discoveries, and
- Departments of Zoology and
| | - Casey P. Shannon
- International Collaboration on Repair Discoveries, and
- Departments of Zoology and
| | - Jason R. Plemel
- International Collaboration on Repair Discoveries, and
- Departments of Zoology and
| | - Yuanyun Xie
- International Collaboration on Repair Discoveries, and
- Departments of Zoology and
| | - Freda D. Miller
- Developmental and Stem Cell Biology Group, Hospital for Sick Children, and
- Departments of Molecular and Medical Genetics and
- Physiology, University of Toronto, Toronto, Ontario, Canada M5G 1L7, and
| | - Wolfram Tetzlaff
- International Collaboration on Repair Discoveries, and
- Departments of Zoology and
- Surgery, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
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157
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Lu P, Tuszynski MH. Growth factors and combinatorial therapies for CNS regeneration. Exp Neurol 2007; 209:313-20. [PMID: 17927983 DOI: 10.1016/j.expneurol.2007.08.004] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Accepted: 08/01/2007] [Indexed: 12/11/2022]
Abstract
There has been remarkable progress in the last 20 years in understanding mechanisms that underlie the success of axonal regeneration in the peripheral nervous system, and the failure of axonal regeneration in the central nervous system. Following the identification of these underlying mechanisms, several distinct therapeutic approaches have been tested in in vivo models of spinal cord injury (SCI) to enhance central axonal structural plasticity, including the therapeutic administration of neurotrophic factors. While several tested mechanisms apparently enhance axonal growth, more recent, properly controlled studies indicate that experimental approaches to combine therapies that target distinct neural mechanisms achieve greater axonal growth than therapies applied in isolation. The search for combination therapies that optimize axonal growth after SCI continues.
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Affiliation(s)
- Paul Lu
- Department of Neurosciences, University of California San Diego, La Jolla, CA 92093-0626, USA
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158
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Abstract
The concept of brain plasticity covers all the mechanisms involved in the capacity of the brain to adjust and remodel itself in response to environmental requirements, experience, skill acquisition, and new challenges including brain lesions. Advances in neuroimaging and neurophysiologic techniques have increased our knowledge of task-related changes in cortical representation areas in the intact and injured human brain. The recognition that neuronal progenitor cells proliferate and differentiate in the subventricular zone and dentate gyrus in the adult mammalian brain has raised the hope that regeneration may be possible after brain lesions. Regeneration will require that new cells differentiate, survive, and integrate into existing neural networks and that axons regenerate. To what extent this will be possible is difficult to predict. Current research explores the possibilities to modify endogenous neurogenesis and facilitate axonal regeneration using myelin inhibitory factors. After apoptotic damage in mice new cortical neurons can form long-distance connections. Progenitor cells from the subventricular zone migrate to cortical and subcortical regions after ischemic brain lesions, apparently directed by signals from the damaged region. Postmortem studies on human brains suggest that neurogenesis may be altered in degenerative diseases. Functional and anatomic data indicate that myelin inhibitory factors, cell implantation, and modification of extracellular matrix may be beneficial after spinal cord lesions. Neurophysiologic data demonstrating that new connections are functioning are needed to prove regeneration. Even if not achieving the goal, methods aimed at regeneration can be beneficial by enhancing plasticity in intact brain regions.
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Affiliation(s)
- Barbro B Johansson
- Wallenberg Neuroscience Center, Department of Clinical Neuroscience, Lund University, Lund, Sweden.
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159
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Cittelly DM, Perez-Polo JR. Antiapoptotic therapies in the treatment of spinal cord injury. FUTURE NEUROLOGY 2007. [DOI: 10.2217/14796708.2.4.425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mechanical trauma to the spinal cord triggers events resulting in the death of neurons and glia over several weeks following the initial injury. It has been suggested that the prevention of delayed apoptosis after spinal cord injury (SCI) is likely to have a beneficial effect by reducing the extent of neuronal and oligodendroglial death, which would translate into better functional outcomes. Drugs acting at different levels in the apoptotic cascade (i.e., caspase inhibitors and antiapoptotic Bcl-xL) have been shown to decrease apoptotic cell death, but benefits in functional outcomes result only when inflammation is also decreased. Furthermore, long-term antiapoptotic therapy can result in nonapoptotic death with necrotic features, which will further increase inflammation and worsen outcome. Even though neuroprotective therapies are one of the targets for the promotion of functional recovery after SCI, targeting only post-SCI apoptosis is unlikely to be as successful as more integrated interventions that also target inflammation.
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Affiliation(s)
- Diana M Cittelly
- Department of Biochemistry, 1430 Tulane Ave, SL43, New Orleans, LA 70112, USA
| | - J Regino Perez-Polo
- University of Texas, Medical Branch at Galveston 301 University Boulevard, Department of Biochemistry & Molecular Biology, Galveston, TX 77555–1072, USA
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160
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Baron-Van Evercooren A, Lachapelle F, Nait-Oumesmar B, Pham-Dinh D. [Promoting myelin repair in disorders such as multiple sclerosis and some types of leukodystrophy: current studies]. Rev Neurol (Paris) 2007; 163:523-31. [PMID: 17571021 DOI: 10.1016/s0035-3787(07)90459-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Several ways of promoting myelin repair in myelin disorders such as multiple sclerosis and certain types of leukodystrophies are currently being investigated. Numerous studies suggest that it is possible to repair the central nervous system (CNS) by cell transplantation or by enhancing endogenous remyelination. Investigations in animal models indicate that cell therapy results in robust anatomical and functional recovery of acute myelin lesions. These models are also used to explore and validate the role of candidate molecules to stimulate endogenous remyelination by activating the myelin competent population or providing neuroprotection. However, in view of the heterogeneity of the lesion environment in MS, it seems more likely that cell therapy alone will not be able to contribute efficiently to the repair of the lesion. Further developments should indicate whether combining multiple approaches will be more powerful to achieve global myelin repair in the CNS than applying these strategies alone.
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161
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Leyssen M, Hassan BA. A fruitfly's guide to keeping the brain wired. EMBO Rep 2007; 8:46-50. [PMID: 17203102 PMCID: PMC1796755 DOI: 10.1038/sj.embor.7400869] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2006] [Accepted: 11/08/2006] [Indexed: 11/09/2022] Open
Abstract
The behaviour of all animals is governed by the connectivity of neural circuits in the brain. Neurodevelopmental and neurodegenerative diseases, as well as traumatic injuries to the nervous system, can alter or disrupt the normal connectivity of the brain and result in disability. In this review, we highlight the contributions of the genetic model organism Drosophila melanogaster to our understanding of neural connectivity in health and disease. In this context we also discuss the research areas in which we believe the fruitfly is likely to be a useful model system in the future.
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Affiliation(s)
- Maarten Leyssen
- Flanders Interuniversity Institute for Biotechnology (VIB)/University of Leuven School of Medicine, Department of Molecular and Developmental Genetics, PO Box 602, Herestraat 49, B-3000 Leuven, Belgium
- Present address: Institute for Molecular Pathology, Dr Bohrgasse 7, 1030 Vienna, Austria
- Tel: +32 16 346226; Fax: +32 16 347190;
| | - Bassem A Hassan
- Flanders Interuniversity Institute for Biotechnology (VIB)/University of Leuven School of Medicine, Department of Molecular and Developmental Genetics, PO Box 602, Herestraat 49, B-3000 Leuven, Belgium
- Tel: +43 1 797 30 423; Fax: +43 1 798 71 53;
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162
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Cittelly DM, Nesic O, Johnson K, Hulsebosch C, Perez-Polo JR. Detrimental effects of antiapoptotic treatments in spinal cord injury. Exp Neurol 2007; 210:295-307. [PMID: 18302959 DOI: 10.1016/j.expneurol.2007.03.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2006] [Revised: 02/27/2007] [Accepted: 03/01/2007] [Indexed: 10/23/2022]
Abstract
Long-term functional impairments due to spinal cord injury (SCI) in the rat result from secondary apoptotic death regulated, in part, by SCI-induced decreases in protein levels of the antiapoptotic protein Bcl-xL. We have shown that exogenous administration of Bcl-xL spares neurons 24 h after SCI. However, long-term effects of chronic application of Bcl-xL have not been characterized. To counteract SCI-induced decreases in Bcl-xL and resulting apoptosis, we used the TAT protein transduction domain fused to the Bcl-xL protein (Tat-Bcl-xL), or its antiapoptotic domain BH4 (Tat-BH4). We used intrathecal delivery of Tat-Bcl-xL, or Tat-BH4, into injured spinal cords for 24 h or 7 days, and apoptosis, neuronal death and locomotor recovery were assessed up to 2 months after injury. Both, Tat-Bcl-xL and Tat-BH4, significantly decreased SCI-induced apoptosis in thoracic segments containing the site of injury (T10) at 24 h or 7 days after SCI. However, the 7-day delivery of Tat-Bcl-xL, or Tat-BH4, also induced a significant impairment of locomotor recovery that lasted beyond the drug delivery time. We found that the 7-day administration of Tat-Bcl-xL, or Tat-BH4, significantly increased non-apoptotic neuronal loss and robustly augmented microglia/macrophage activation. These results indicate that the antiapoptotic treatment targeting Bcl-xL shifts neuronal apoptosis to necrosis, increases the inflammatory response and impairs locomotor recovery. Our results suggest that a combinatorial treatment consisting of antiapoptotic and anti-inflammatory agents may be necessary to achieve tissue preservation and significant improvement in functional recovery after SCI.
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Affiliation(s)
- Diana M Cittelly
- Neurosciences and Cell Biology, University of Texas Medical Branch, Galveston, Texas 77555, USA
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163
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Woolfe F, Waxman SG, Hains BC. In SilicoModeling of Axonal Reconnection within A Discrete Fiber Tract after Spinal Cord Injury. J Neurotrauma 2007; 24:421-32. [PMID: 17376004 DOI: 10.1089/neu.2006.0131] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Following spinal cord injury (SCI), descending axons that carry motor commands from the brain to the spinal cord are injured or transected, producing chronic motor dysfunction and paralysis. Reconnection of these axons is a major prerequisite for restoration of function after SCI. Thus far, only modest gains in motor function have been achieved experimentally or in the clinic after SCI, identifying the practical limitations of current treatment approaches. In this paper, we use an ordinary differential equation (ODE) to simulate the relative and synergistic contributions of several experimentally-established biological factors related to inhibition or promotion of axonal repair and restoration of function after SCI. The factors were mathematically modeled by the ODE. The results of our simulation show that in a model system, many factors influenced the achievability of axonal reconnection. Certain factors more strongly affected axonal reconnection in isolation, and some factors interacted in a synergistic fashion to produce further improvements in axonal reconnection. Our data suggest that mathematical modeling may be useful in evaluating the complex interactions of discrete therapeutic factors not possible in experimental preparations, and highlight the benefit of a combinatorial therapeutic approach focused on promoting axonal sprouting, attraction of cut ends, and removal of growth inhibition for achieving axonal reconnection. Predictions of this simulation may be of utility in guiding future experiments aimed at restoring function after SCI.
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Affiliation(s)
- Franco Woolfe
- Department of Applied Mathematics, Yale University, New Haven, Connecticut 06516, USA
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164
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Bramlett HM, Dietrich WD. Progressive damage after brain and spinal cord injury: pathomechanisms and treatment strategies. PROGRESS IN BRAIN RESEARCH 2007; 161:125-41. [PMID: 17618974 DOI: 10.1016/s0079-6123(06)61009-1] [Citation(s) in RCA: 238] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The pathophysiology of brain and spinal cord injury (SCI) is complex and involves multiple injury mechanisms that are spatially and temporally specific. It is now appreciated that many of these injury mechanisms remain active days to weeks after a primary insult. Long-term survival studies in clinically relevant experimental studies have documented the structural changes that continue at the level of the insult as well as in remote brain structures. After traumatic brain injury (TBI), progressive atrophy of both gray and white matter structures continues up to 1 year post-trauma. Progressive changes may therefore underlie some of the long-term functional deficits observed in this patient population. After SCI, similar features of progressive injury are observed including delayed cell death of neurons and oligodendrocytes, axonal demyelination of intact fiber tracts and retrograde tract degeneration. SCI also leads to supraspinal changes in cell survival and remote brain circuitry. The progressive changes in multiple structures after brain and SCI are important because of their potential consequences on chronic or developing neurological deficits associated with these insults. In addition, the better understanding of these injury cascades may one day allow new treatments to be developed that can inhibit these responses to injury and hopefully promote recovery. This chapter summarizes some of the recent data regarding progressive damage after CNS trauma and mechanisms underlying these changes.
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Affiliation(s)
- Helen M Bramlett
- Department of Neurological Surgery, Neurotrauma Research Center, The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, 1095 NW 14th Terrace, Miami, FL 33136, USA.
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165
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Sasaki M, Li B, Lankford KL, Radtke C, Kocsis JD. Remyelination of the injured spinal cord. PROGRESS IN BRAIN RESEARCH 2007; 161:419-33. [PMID: 17618995 PMCID: PMC2605400 DOI: 10.1016/s0079-6123(06)61030-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Contusive spinal cord injury (SCI) can result in necrosis of the spinal cord, but often long white matter tracts outside of the central necrotic core are demyelinated. One experimental strategy to improve functional outcome following SCI is to transplant myelin-forming cells to remyelinate these axons and improve conduction. This review focuses on transplantation studies using olfactory ensheathing cell (OEC) to improve functional outcome in experimental models of SCI and demyelination. The biology of the OEC, and recent experimental research and clinical studies using OECs as a potential cell therapy candidate are discussed.
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Affiliation(s)
- Masanori Sasaki
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA
- Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Bingcang Li
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA
- Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516, USA
- Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, P.R. China
| | - Karen L. Lankford
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA
- Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Christine Radtke
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA
- Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516, USA
- Department of Plastic, Hand and Reconstructive Surgery, Medical School Hannover, Hannover, Germany
| | - Jeffery D. Kocsis
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA
- Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT 06516, USA
- Corresponding author. Tel.: +1-(203)-937-3802; Fax: +1-(203)-937-3801; E-mail:
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166
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Tang BL, Low CB. Genetic Manipulation of Neural Stem Cells for Transplantation into the Injured Spinal Cord. Cell Mol Neurobiol 2006; 27:75-85. [PMID: 17151948 DOI: 10.1007/s10571-006-9119-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2006] [Accepted: 09/06/2006] [Indexed: 12/20/2022]
Abstract
The injured adult spinal cord is not conducive for neuronal regeneration and neurogenesis. Engrafted neural precursor cells (NPCs) differentiate largely into astroglia, with only a very small percentage becoming neurons (which might replace injured neurons) or oligodendroglia (which might improve injury induced demyelination of spared neurons). Several recent attempts have been made to enhanced neurogenesis or oligodendroglia differentiation of transplanted NPCs by genetic manipulation. These include exogenous expression of noggin, with the idea of antagonizing the astroglia differentiation promoting Bone Morphogenetic Proteins (BMPs). Direct attempts to enhance neurogenesis have also been made in transgenic over-expression of neurogenic basic helix-loop-helix transcription factors. These experiments resulted in some interesting observations, which we discuss here in the light of recent advances in development of cell-based engraftment therapy for spinal cord injuries.
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Affiliation(s)
- Bor Luen Tang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Garden City, Singapore.
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167
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Hakkoum D, Stoppini L, Muller D. Interleukin-6 promotes sprouting and functional recovery in lesioned organotypic hippocampal slice cultures. J Neurochem 2006; 100:747-57. [PMID: 17144903 DOI: 10.1111/j.1471-4159.2006.04257.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Interleukin (IL)-6 is a pro-inflammatory cytokine now widely recognized to contribute to the molecular events that follow CNS injury. Little is known, however, about its action on axonal sprouting and regeneration in the brain. We addressed this issue using the model of transection of Schaffer collaterals in mice organotypic hippocampal slice cultures. Transection of slice cultures was associated with a marked release of IL-6 that could be neutralized by an IL-6 blocking antibody. We monitored functional recovery across the lesion by recording synaptic responses using a multi-electrode array. We found that application of IL-6 antibodies to the cultures after lesioning significantly reduced functional recovery across the lesion. Furthermore, the level of expression of the 43-kDa growth-associated protein (GAP-43) was lower in slices treated with the IL-6 neutralizing antibody than in those treated with a control IgG. Conversely, addition of exogenous IL-6 to the culture medium resulted in a dose-dependent enhancement of functional recovery across the lesion and a higher level of expression of GAP-43. Co-culture of CA3 hemi-slices from thy1-YFP mice with CA1 hemi-slices from wild-type animals confirmed that IL-6-treated co-cultures exhibited an increased number of growing fluorescent fibres across the lesion site. Taken together these data indicate that IL-6 plays an important role in CNS repair mechanisms by promoting regrowth and axon regeneration.
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Affiliation(s)
- David Hakkoum
- Department of Basic Neurosciences, University of Geneva, Geneva, Switzerland.
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168
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Abstract
Abstract
OBJECTIVE
To provide a comprehensive review of the treatment trials in the field of spinal cord injury, emphasizing what has been learned about the effectiveness of the agents and strategies tested and the quality of the methodology. The review aims to provide useful information for the improvement of future trials. The review audience includes practitioners, researchers, and consumers.
METHODS
All publications describing organized trials since the 1960s were analyzed in detail, emphasizing randomized, prospective controlled trials and published Phase I and II trials. Trials were categorized into neuroprotection, surgery, regeneration, and rehabilitation trials. Special attention was paid to design, outcome measures, and case selection.
RESULTS
There are 10 randomized prospective control trials in the acute phase that have provided much useful information. Current neurological grading systems are greatly improved, but still have significant shortcomings, and independent, trained, and blinded examiners are mandatory. Other trial designs should be considered, especially those using adaptive randomization. Only methylprednisolone and thyrotropin-releasing hormone have been shown to be effective, but the results of the former are controversial, and studies involving the latter involved too few patients. None of the surgical trials has proven effectiveness. Currently, a multitude of cell-based Phase I trials in several countries are attracting large numbers of patients, but such treatments are unproven in effectiveness and may cause harm. Only a small number are being conducted in a randomized or blinded format. Several consortia have committed to a promise to improve the conduct of trials.
CONCLUSION
A large number of trials in the field of spinal cord injury have been conducted, but with few proven gains for patients. This review reveals several shortcomings in trial design and makes several recommendations for improvement.
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Affiliation(s)
- Charles H Tator
- Division of Neurosurgery, Toronto Western Hospital, 399 Bathurst Street, Suite 4W-433, Toronto, ON M5T 2S8, Canada.
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