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Wang Y, Su H, Zhong J, Zhan Z, Zhao Q, Liu Y, Li S, Wang H, Yang C, Yu L, Tan B, Yin Y. Osteopontin enhances the effect of treadmill training and promotes functional recovery after spinal cord injury. MOLECULAR BIOMEDICINE 2023; 4:44. [PMID: 38015348 PMCID: PMC10684450 DOI: 10.1186/s43556-023-00154-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Accepted: 11/05/2023] [Indexed: 11/29/2023] Open
Abstract
In this study, we examined the combined impact of osteopontin (OPN) and treadmill training on mice with spinal cord injury (SCI). OPN was overexpressed by injecting AAV9-SPP1-GFP into the sensorimotor cortex, followed by a left incomplete C5 crush injury two weeks later. Mice (Ex or Ex + OPN group) were trained at 50% maximum running speed for 8 weeks. To analyze the effects, we used biotinylated dextran amine (BDA) for tracing the corticospinal tract (CST) and performed Western blotting and immunohistochemical methods to assess the activation of the mammalian target of rapamycin (mTOR). We also examined axonal regeneration and conducted behavioral tests to measure functional recovery. The results demonstrated that treadmill training promoted the expression of neurotrophic factors such as brain-derived neurotrophic factor (BNDF) and insulin-like growth factor I (IGF-1) and activated mTOR signaling. OPN amplified the effect of treadmill training on activating mTOR signaling indicated by upregulated phosphorylation of ribosomal protein S6 kinase (S6). The combination of OPN and exercise further promoted functional recovery and facilitated limited CST axonal regeneration which did not occur with treadmill training and OPN treatment alone. These findings indicate that OPN enhances the effects of treadmill training in the treatment of SCI and offer new therapeutic insights for spinal cord injury.
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Affiliation(s)
- Yunhang Wang
- Department of Rehabilitation Medicine, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, 400010, China
- Department of Rehabilitation, Zhejiang University School of Medicine Second Affiliated Hospital, 88 Jiefang Road, Hangzhou, Zhejiang, 310009, China
| | - Hong Su
- Department of Rehabilitation Medicine, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, 400010, China
| | - Juan Zhong
- Department of Rehabilitation Medicine, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, 400010, China
| | - Zuxiong Zhan
- Department of Rehabilitation Medicine, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, 400010, China
| | - Qin Zhao
- Department of Rehabilitation Medicine, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, 400010, China
| | - Yuan Liu
- State Key Laboratory of Trauma, Burns and Combined Injury, Department of Special War Wound, Daping Hospital, Army Medical University, Chongqing, 400042, China
| | - Sen Li
- State Key Laboratory of Trauma, Burns and Combined Injury, Department of Special War Wound, Daping Hospital, Army Medical University, Chongqing, 400042, China
| | - Haiyan Wang
- State Key Laboratory of Trauma, Burns and Combined Injury, Department of Special War Wound, Daping Hospital, Army Medical University, Chongqing, 400042, China
| | - Ce Yang
- State Key Laboratory of Trauma, Burns and Combined Injury, Department of Special War Wound, Daping Hospital, Army Medical University, Chongqing, 400042, China
| | - Lehua Yu
- Department of Rehabilitation Medicine, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, 400010, China
| | - Botao Tan
- Department of Rehabilitation Medicine, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, 400010, China.
| | - Ying Yin
- Department of Rehabilitation Medicine, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, 400010, China.
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Paramasivam A, Mickymaray S, Jayakumar S, Jeraud M, Perumal P, Alassaf A, Aljabr AA, Dasarathy S, Rangasamy SB. Locomotor Behavior Analysis in Spinal Cord Injured Macaca radiata after Predegenerated Peripheral Nerve Grafting-A Preliminary Evidence. Vet Sci 2021; 8:vetsci8120288. [PMID: 34941815 PMCID: PMC8707676 DOI: 10.3390/vetsci8120288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 11/16/2021] [Accepted: 11/19/2021] [Indexed: 11/16/2022] Open
Abstract
INTRODUCTION Primate animal models are being utilized to explore novel therapies for spinal cord injuries. This study aimed to evaluate the efficiency of the transplantation of predegenerated nerve segments in unilateral spinal cord-hemisected bonnet monkeys' (Macaca radiata) locomotor functions using the complex runways. MATERIALS AND METHODS The bonnet monkeys were initially trained to walk in a bipedal motion on grid and staircase runways. In one group of trained monkeys, surgical hemisection was made in the spinal cord at the T12-L1 level. In the other group, hemisection was induced in the spinal cord, and the ulnar nerve was also transected at the same time (transplant group). After one week, the hemisected cavity was reopened and implanted with predegenerated ulnar nerve segments obtained from the same animal of the transplant group. RESULTS All the operated monkeys showed significant deficits in locomotion on runways at the early postoperative period. The walking ability of operated monkeys was found to be gradually improved, and they recovered nearer to preoperative level at the fourth postoperative month, and there were no marked differences. CONCLUSION The results demonstrate that there were no significant improvements in the locomotion of monkeys on runways after the delayed grafting of nerve segments until one year later. The failure of the predegenerated nerve graft as a possible therapeutic strategy to improve the locomotion of monkeys may be due to a number of factors set in motion by trauma, which could possibly prevent the qualities of regeneration. The exact reason for this ineffectiveness of predegenerated nerve segments and their underlying mechanism is not known.
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Affiliation(s)
- Anand Paramasivam
- Department of Basic Medical Sciences, College of Dentistry, Majmaah University, Al-Majmaah 11952, Saudi Arabia;
- Department of Physiology, Dr. ALM PGIBMS, University of Madras, Chennai 600113, India; (M.J.); (P.P.); (S.B.R.)
- Department of Medical Education, College of Dentistry, Majmaah University, Majmaah 11952, Saudi Arabia;
- Correspondence:
| | - Suresh Mickymaray
- Department of Biology, College of Science, Majmaah University, Majmaah 11952, Saudi Arabia;
| | - Saikarthik Jayakumar
- Department of Basic Medical Sciences, College of Dentistry, Majmaah University, Al-Majmaah 11952, Saudi Arabia;
- Department of Medical Education, College of Dentistry, Majmaah University, Majmaah 11952, Saudi Arabia;
| | - Mathew Jeraud
- Department of Physiology, Dr. ALM PGIBMS, University of Madras, Chennai 600113, India; (M.J.); (P.P.); (S.B.R.)
- Department of Physiology, Ibn Sina National College for Medical Studies, Jeddah 22421, Saudi Arabia
| | - Periasamy Perumal
- Department of Physiology, Dr. ALM PGIBMS, University of Madras, Chennai 600113, India; (M.J.); (P.P.); (S.B.R.)
- Department of Physiology, Vellore Medical College, Vellore 632002, India
| | - Abdullah Alassaf
- Department of Preventive Dental Sciences, College of Dentistry, Majmaah University, Majmaah 11952, Saudi Arabia;
| | | | - Sridevi Dasarathy
- Department of Neurological Sciences, Rush University Medical Centre, Chicago, IL 60612, USA;
| | - Suresh Babu Rangasamy
- Department of Physiology, Dr. ALM PGIBMS, University of Madras, Chennai 600113, India; (M.J.); (P.P.); (S.B.R.)
- Department of Neurological Sciences, Rush University Medical Centre, Chicago, IL 60612, USA;
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Muheremu A, Shu L, Liang J, Aili A, Jiang K. Sustained delivery of neurotrophic factors to treat spinal cord injury. Transl Neurosci 2021; 12:494-511. [PMID: 34900347 PMCID: PMC8633588 DOI: 10.1515/tnsci-2020-0200] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 11/04/2021] [Accepted: 11/05/2021] [Indexed: 12/16/2022] Open
Abstract
Acute spinal cord injury (SCI) is a devastating condition that results in tremendous physical and psychological harm and a series of socioeconomic problems. Although neurons in the spinal cord need neurotrophic factors for their survival and development to reestablish their connections with their original targets, endogenous neurotrophic factors are scarce and the sustainable delivery of exogeneous neurotrophic factors is challenging. The widely studied neurotrophic factors such as brain-derived neurotrophic factor, neurotrophin-3, nerve growth factor, ciliary neurotrophic factor, basic fibroblast growth factor, and glial cell-derived neurotrophic factor have a relatively short cycle that is not sufficient enough for functionally significant neural regeneration after SCI. In the past decades, scholars have tried a variety of cellular and viral vehicles as well as tissue engineering scaffolds to safely and sustainably deliver those necessary neurotrophic factors to the injury site, and achieved satisfactory neural repair and functional recovery on many occasions. Here, we review the neurotrophic factors that have been used in trials to treat SCI, and vehicles that were commonly used for their sustained delivery.
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Affiliation(s)
- Aikeremujiang Muheremu
- Department of Spine Surgery, Sixth Affiliated Hospital of Xinjiang Medical University, 39 Wuxing Nan Rd, Tianshan District, Urumqi, Xinjiang, 86830001, People’s Republic of China
| | - Li Shu
- Department of Orthopedics, Sixth Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang, 86830001, People’s Republic of China
| | - Jing Liang
- Department of Laboratory Medicine, Sixth Affiliated Hospital of Xinjiang Medical University, 39, Wuxing Nan Rd, Tianshan District, Urumqi, Xinjiang, 86830001, People’s Republic of China
| | - Abudunaibi Aili
- Department of Spine Surgery, Sixth Affiliated Hospital of Xinjiang Medical University, 39 Wuxing Nan Rd, Tianshan District, Urumqi, Xinjiang, 86830001, People’s Republic of China
| | - Kan Jiang
- Department of Orthopedics, Sixth Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang, 86830001, People’s Republic of China
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Petrova V, Eva R. The Virtuous Cycle of Axon Growth: Axonal Transport of Growth-Promoting Machinery as an Intrinsic Determinant of Axon Regeneration. Dev Neurobiol 2018; 78:898-925. [PMID: 29989351 DOI: 10.1002/dneu.22608] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 05/25/2018] [Accepted: 05/26/2018] [Indexed: 02/02/2023]
Abstract
Injury to the brain and spinal cord has devastating consequences because adult central nervous system (CNS) axons fail to regenerate. Injury to the peripheral nervous system (PNS) has a better prognosis, because adult PNS neurons support robust axon regeneration over long distances. CNS axons have some regenerative capacity during development, but this is lost with maturity. Two reasons for the failure of CNS regeneration are extrinsic inhibitory molecules, and a weak intrinsic capacity for growth. Extrinsic inhibitory molecules have been well characterized, but less is known about the neuron-intrinsic mechanisms which prevent axon re-growth. Key signaling pathways and genetic/epigenetic factors have been identified which can enhance regenerative capacity, but the precise cellular mechanisms mediating their actions have not been characterized. Recent studies suggest that an important prerequisite for regeneration is an efficient supply of growth-promoting machinery to the axon; however, this appears to be lacking from non-regenerative axons in the adult CNS. In the first part of this review, we summarize the evidence linking axon transport to axon regeneration. We discuss the developmental decline in axon regeneration capacity in the CNS, and comment on how this is paralleled by a similar decline in the selective axonal transport of regeneration-associated receptors such as integrins and growth factor receptors. In the second part, we discuss the mechanisms regulating selective polarized transport within neurons, how these relate to the intrinsic control of axon regeneration, and whether they can be targeted to enhance regenerative capacity. © 2018 Wiley Periodicals, Inc. Develop Neurobiol 00: 000-000, 2018.
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Affiliation(s)
- Veselina Petrova
- John Van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 OPY, United Kingdom
| | - Richard Eva
- John Van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 OPY, United Kingdom
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5
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Hodgetts SI, Harvey AR. Neurotrophic Factors Used to Treat Spinal Cord Injury. VITAMINS AND HORMONES 2016; 104:405-457. [PMID: 28215303 DOI: 10.1016/bs.vh.2016.11.007] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The application of neurotrophic factors as a therapy to improve morphological and behavioral outcomes after experimental spinal cord injury (SCI) has been the focus of many studies. These studies vary markedly in the type of neurotrophic factor that is delivered, the mode of administration, and the location, timing, and duration of the treatment. Generally, the majority of studies have had significant success if neurotrophic factors are applied in or close to the lesion site during the acute or the subacute phase after SCI. Comparatively fewer studies have administered neurotrophic factors in order to directly target the somata of injured neurons. The mode of delivery varies between acute injection of recombinant proteins, subacute or chronic delivery using a variety of strategies including osmotic minipumps, cell-mediated delivery, delivery using polymer release vehicles or supporting bridges of some sort, or the use of gene therapy to modify neurons, glial cells, or precursor/stem cells. In this brief review, we summarize the state of play of many of the therapies using these factors, most of which have been undertaken in rodent models of SCI.
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Affiliation(s)
- S I Hodgetts
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, Perth, WA, Australia; Western Australian Neuroscience Research Institute, Perth, WA, Australia.
| | - A R Harvey
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, Perth, WA, Australia; Western Australian Neuroscience Research Institute, Perth, WA, Australia
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6
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Siebert JR, Eade AM, Osterhout DJ. Biomaterial Approaches to Enhancing Neurorestoration after Spinal Cord Injury: Strategies for Overcoming Inherent Biological Obstacles. BIOMED RESEARCH INTERNATIONAL 2015; 2015:752572. [PMID: 26491685 PMCID: PMC4600545 DOI: 10.1155/2015/752572] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 07/22/2015] [Indexed: 01/14/2023]
Abstract
While advances in technology and medicine have improved both longevity and quality of life in patients living with a spinal cord injury, restoration of full motor function is not often achieved. This is due to the failure of repair and regeneration of neuronal connections in the spinal cord after injury. In this review, the complicated nature of spinal cord injury is described, noting the numerous cellular and molecular events that occur in the central nervous system following a traumatic lesion. In short, postinjury tissue changes create a complex and dynamic environment that is highly inhibitory to the process of neural regeneration. Strategies for repair are outlined with a particular focus on the important role of biomaterials in designing a therapeutic treatment that can overcome this inhibitory environment. The importance of considering the inherent biological response of the central nervous system to both injury and subsequent therapeutic interventions is highlighted as a key consideration for all attempts at improving functional recovery.
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Affiliation(s)
- Justin R. Siebert
- Lake Erie College of Osteopathic Medicine at Seton Hill, Greensburg, PA 15601, USA
| | - Amber M. Eade
- Lake Erie College of Osteopathic Medicine at Seton Hill, Greensburg, PA 15601, USA
| | - Donna J. Osterhout
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, NY 13210, USA
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7
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Challagundla M, Koch JC, Ribas VT, Michel U, Kügler S, Ostendorf T, Bradke F, Müller HW, Bähr M, Lingor P. AAV-mediated expression of BAG1 and ROCK2-shRNA promote neuronal survival and axonal sprouting in a rat model of rubrospinal tract injury. J Neurochem 2015; 134:261-75. [DOI: 10.1111/jnc.13102] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Revised: 02/14/2015] [Accepted: 03/06/2015] [Indexed: 11/27/2022]
Affiliation(s)
| | - Jan Christoph Koch
- Department of Neurology; University Medicine Göttingen; Göttingen Germany
| | | | - Uwe Michel
- Department of Neurology; University Medicine Göttingen; Göttingen Germany
| | - Sebastian Kügler
- Department of Neurology; University Medicine Göttingen; Göttingen Germany
| | - Thomas Ostendorf
- Department of Neurology; University Medicine Göttingen; Göttingen Germany
| | - Frank Bradke
- German Center for Neurodegenerative Diseases (DZNE); Bonn Germany
| | - Hans Werner Müller
- Department of Neurology; Molecular Neurobiology Laboratory; Heinrich-Heine-University Medical Center Düsseldorf; Düsseldorf Germany
| | - Mathias Bähr
- Department of Neurology; University Medicine Göttingen; Göttingen Germany
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB); Göttingen Germany
| | - Paul Lingor
- Department of Neurology; University Medicine Göttingen; Göttingen Germany
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB); Göttingen Germany
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8
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Harvey AR, Lovett SJ, Majda BT, Yoon JH, Wheeler LPG, Hodgetts SI. Neurotrophic factors for spinal cord repair: Which, where, how and when to apply, and for what period of time? Brain Res 2014; 1619:36-71. [PMID: 25451132 DOI: 10.1016/j.brainres.2014.10.049] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 10/20/2014] [Accepted: 10/23/2014] [Indexed: 12/22/2022]
Abstract
A variety of neurotrophic factors have been used in attempts to improve morphological and behavioural outcomes after experimental spinal cord injury (SCI). Here we review many of these factors, their cellular targets, and their therapeutic impact on spinal cord repair in different, primarily rodent, models of SCI. A majority of studies report favourable outcomes but results are by no means consistent, thus a major aim of this review is to consider how best to apply neurotrophic factors after SCI to optimize their therapeutic potential. In addition to which factors are chosen, many variables need be considered when delivering trophic support, including where and when to apply a given factor or factors, how such factors are administered, at what dose, and for how long. Overall, the majority of studies have applied neurotrophic support in or close to the spinal cord lesion site, in the acute or sub-acute phase (0-14 days post-injury). Far fewer chronic SCI studies have been undertaken. In addition, comparatively fewer studies have administered neurotrophic factors directly to the cell bodies of injured neurons; yet in other instructive rodent models of CNS injury, for example optic nerve crush or transection, therapies are targeted directly at the injured neurons themselves, the retinal ganglion cells. The mode of delivery of neurotrophic factors is also an important variable, whether delivered by acute injection of recombinant proteins, sub-acute or chronic delivery using osmotic minipumps, cell-mediated delivery, delivery using polymer release vehicles or supporting bridges of some sort, or the use of gene therapy to modify neurons, glial cells or precursor/stem cells. Neurotrophic factors are often used in combination with cell or tissue grafts and/or other pharmacotherapeutic agents. Finally, the dose and time-course of delivery of trophic support should ideally be tailored to suit specific biological requirements, whether they relate to neuronal survival, axonal sparing/sprouting, or the long-distance regeneration of axons ending in a different mode of growth associated with terminal arborization and renewed synaptogenesis. This article is part of a Special Issue entitled SI: Spinal cord injury.
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Affiliation(s)
- Alan R Harvey
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
| | - Sarah J Lovett
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Bernadette T Majda
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Jun H Yoon
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Lachlan P G Wheeler
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Stuart I Hodgetts
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
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9
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Viscomi MT, Molinari M. Remote neurodegeneration: multiple actors for one play. Mol Neurobiol 2014; 50:368-89. [PMID: 24442481 DOI: 10.1007/s12035-013-8629-x] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 12/24/2013] [Indexed: 12/19/2022]
Abstract
Remote neurodegeneration significantly influences the clinical outcome in many central nervous system (CNS) pathologies, such as stroke, multiple sclerosis, and traumatic brain and spinal cord injuries. Because these processes develop days or months after injury, they are accompanied by a therapeutic window of opportunity. The complexity and clinical significance of remote damage is prompting many groups to examine the factors of remote degeneration. This research is providing insights into key unanswered questions, opening new avenues for innovative neuroprotective therapies. In this review, we evaluate data from various remote degeneration models to describe the complexity of the systems that are involved and the importance of their interactions in reducing damage and promoting recovery after brain lesions. Specifically, we recapitulate the current data on remote neuronal degeneration, focusing on molecular and cellular events, as studied in stroke and brain and spinal cord injury models. Remote damage is a multifactorial phenomenon in which many components become active in specific time frames. Days, weeks, or months after injury onset, the interplay between key effectors differentially affects neuronal survival and functional outcomes. In particular, we discuss apoptosis, inflammation, oxidative damage, and autophagy-all of which mediate remote degeneration at specific times. We also review current findings on the pharmacological manipulation of remote degeneration mechanisms in reducing damage and sustaining outcomes. These novel treatments differ from those that have been proposed to limit primary lesion site damage, representing new perspectives on neuroprotection.
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Affiliation(s)
- Maria Teresa Viscomi
- Experimental Neurorehabilitation Laboratory, Santa Lucia Foundation I.R.C.C.S., Via del Fosso di Fiorano 65, 00143, Rome, Italy,
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10
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Silva NA, Sousa N, Reis RL, Salgado AJ. From basics to clinical: a comprehensive review on spinal cord injury. Prog Neurobiol 2013; 114:25-57. [PMID: 24269804 DOI: 10.1016/j.pneurobio.2013.11.002] [Citation(s) in RCA: 509] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 11/12/2013] [Accepted: 11/12/2013] [Indexed: 12/15/2022]
Abstract
Spinal cord injury (SCI) is a devastating neurological disorder that affects thousands of individuals each year. Over the past decades an enormous progress has been made in our understanding of the molecular and cellular events generated by SCI, providing insights into crucial mechanisms that contribute to tissue damage and regenerative failure of injured neurons. Current treatment options for SCI include the use of high dose methylprednisolone, surgical interventions to stabilize and decompress the spinal cord, and rehabilitative care. Nonetheless, SCI is still a harmful condition for which there is yet no cure. Cellular, molecular, rehabilitative training and combinatorial therapies have shown promising results in animal models. Nevertheless, work remains to be done to ascertain whether any of these therapies can safely improve patient's condition after human SCI. This review provides an extensive overview of SCI research, as well as its clinical component. It starts covering areas from physiology and anatomy of the spinal cord, neuropathology of the SCI, current clinical options, neuronal plasticity after SCI, animal models and techniques to assess recovery, focusing the subsequent discussion on a variety of promising neuroprotective, cell-based and combinatorial therapeutic approaches that have recently moved, or are close, to clinical testing.
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Affiliation(s)
- Nuno A Silva
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Nuno Sousa
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Rui L Reis
- ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal; 3B's Research Group - Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, 4806-909 Caldas das Taipas, Guimarães, Portugal
| | - António J Salgado
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.
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Exogenous BDNF enhances the integration of chronically injured axons that regenerate through a peripheral nerve grafted into a chondroitinase-treated spinal cord injury site. Exp Neurol 2012; 239:91-100. [PMID: 23022460 DOI: 10.1016/j.expneurol.2012.09.011] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Revised: 08/03/2012] [Accepted: 09/20/2012] [Indexed: 12/20/2022]
Abstract
Although axons lose some of their intrinsic capacity for growth after their developmental period, some axons retain the potential for regrowth after injury. When provided with a growth-promoting substrate such as a peripheral nerve graft (PNG), severed axons regenerate into and through the graft; however, they stop when they reach the glial scar at the distal graft-host interface that is rich with inhibitory chondroitin sulfate proteoglycans. We previously showed that treatment of a spinal cord injury site with chondroitinase (ChABC) allows axons within the graft to traverse the scar and reinnervate spinal cord, where they form functional synapses. While this improvement in outgrowth was significant, it still represented only a small percentage (<20%) of axons compared to the total number of axons that regenerated into the PNG. Here we tested whether providing exogenous brain-derived neurotrophic factor (BDNF) via lentivirus in tissue distal to the PNG would augment regeneration beyond a ChABC-treated glial interface. We found that ChABC treatment alone promoted axonal regeneration but combining ChABC with BDNF-lentivirus did not increase the number of axons that regenerated back into spinal cord. Combining BDNF with ChABC did increase the number of spinal cord neurons that were trans-synaptically activated during electrical stimulation of the graft, as indicated by c-Fos expression, suggesting that BDNF overexpression improved the functional significance of axons that did reinnervate distal spinal cord tissue.
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Weishaupt N, Blesch A, Fouad K. BDNF: the career of a multifaceted neurotrophin in spinal cord injury. Exp Neurol 2012; 238:254-64. [PMID: 22982152 DOI: 10.1016/j.expneurol.2012.09.001] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 08/30/2012] [Accepted: 09/02/2012] [Indexed: 12/19/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) has been identified as a potent promoter of neurite growth, a finding that has led to an ongoing exploration of this neurotrophin as a potential treatment for spinal cord injury. BDNF's many effects in the nervous system make it an excellent candidate for neuroprotective strategies as well as for promoting axonal regeneration, plasticity and re-myelination. In addition, neuronal activity and physical exercise can modulate the expression of BDNF, suggesting that non-invasive means to increase BDNF levels might exist. Nonetheless, depending on the location, amount and duration of BDNF delivery, this potent neurotrophin can also have adverse effects, such as modulation of nociceptive pathways or contribution to spasticity. Taken together, the benefits and possible risks require careful assessment when considering this multifaceted neurotrophin as a treatment option for spinal cord injury.
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Affiliation(s)
- N Weishaupt
- Centre for Neuroscience, University of Alberta, Edmonton, Canada.
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Receptor tyrosine kinases: molecular switches regulating CNS axon regeneration. JOURNAL OF SIGNAL TRANSDUCTION 2012; 2012:361721. [PMID: 22848811 PMCID: PMC3405719 DOI: 10.1155/2012/361721] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Accepted: 06/04/2012] [Indexed: 01/04/2023]
Abstract
The poor or lack of injured adult central nervous system (CNS) axon regeneration results in devastating consequences and poor functional recovery. The interplay between the intrinsic and extrinsic factors contributes to robust inhibition of axon regeneration of injured CNS neurons. The insufficient or lack of trophic support for injured neurons is considered as one of the major obstacles contributing to their failure to survive and regrow their axons after injury. In the CNS, many of the signalling pathways associated with neuronal survival and axon regeneration are regulated by several classes of receptor tyrosine kinases (RTK) that respond to a variety of ligands. This paper highlights and summarises the most relevant recent findings pertinent to different classes of the RTK family of molecules, with a particular focus on elucidating their role in CNS axon regeneration.
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Carter LM, McMahon SB, Bradbury EJ. Delayed treatment with chondroitinase ABC reverses chronic atrophy of rubrospinal neurons following spinal cord injury. Exp Neurol 2011; 228:149-56. [PMID: 21215745 DOI: 10.1016/j.expneurol.2010.12.023] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Revised: 12/04/2010] [Accepted: 12/24/2010] [Indexed: 01/05/2023]
Abstract
Degradation of extracellular matrix chondroitin sulphate proteoglycans (CSPGs) using Chondroitinase ABC (ChABC) is a promising strategy for the treatment of spinal cord injury, with potent effects on promoting functional recovery and anatomical repair in spinal injured animals. We have previously demonstrated that ChABC treatment prevents atrophy of corticospinal projection neurons following spinal injury in adult YFP-H mice. Here, we investigate whether ChABC-mediated repair of the cell body extends to rubrospinal projection neurons (RSNs), whether neuroprotective effects can be sustained long-term and importantly, whether delayed treatment with ChABC can reverse chronic atrophy. Adult YFP-H mice underwent unilateral rubrospinal tract transection and were treated with ChABC or a control enzyme, delivered either acutely post-injury or after a one month delay. Eight weeks following injury and control treatment, RSNs in the injured red nucleus, identified by YFP label and NeuN immunoreactivity, showed severe atrophy, with ~40% loss of mean cell area compared to uninjured neurons in the contralateral red nucleus. Both acute and delayed treatment with ChABC promoted a significant rescue of injured RSNs, restoring cell area to ~80% and ~70%, respectively, of that in uninjured neurons. Thus, we demonstrate for the first time that CSPG degradation in the injured spinal cord not only promotes sustained rescue of cell atrophy when delivered acutely but can also reverse chronic atrophy in descending projection neurons. Thus, modulation of the extracellular matrix can mediate neuroprotective effects both early and late after spinal cord injury.
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Affiliation(s)
- Lucy M Carter
- King's College London, Neurorestoration Group, Wolfson Centre for Age Related Diseases, Wolfson Wing, Hodgkin Building, Guy's Campus, London Bridge, London SE1 1UL, UK.
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Viscomi M, Oddi S, Latini L, Bisicchia E, Maccarrone M, Molinari M. The endocannabinoid system: A new entry in remote cell death mechanisms. Exp Neurol 2010; 224:56-65. [DOI: 10.1016/j.expneurol.2010.03.023] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Accepted: 03/25/2010] [Indexed: 10/19/2022]
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Plunet WT, Lam CK, Lee JHT, Liu J, Tetzlaff W. Prophylactic dietary restriction may promote functional recovery and increase lifespan after spinal cord injury. Ann N Y Acad Sci 2010; 1198 Suppl 1:E1-11. [DOI: 10.1111/j.1749-6632.2010.05564.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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17
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Blits B, Derks S, Twisk J, Ehlert E, Prins J, Verhaagen J. Adeno-associated viral vector (AAV)-mediated gene transfer in the red nucleus of the adult rat brain: Comparative analysis of the transduction properties of seven AAV serotypes and lentiviral vectors. J Neurosci Methods 2010; 185:257-63. [DOI: 10.1016/j.jneumeth.2009.10.009] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Revised: 10/08/2009] [Accepted: 10/09/2009] [Indexed: 10/20/2022]
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Wannier-Morino P, Schmidlin E, Freund P, Belhaj-Saif A, Bloch J, Mir A, Schwab M, Rouiller E, Wannier T. Fate of rubrospinal neurons after unilateral section of the cervical spinal cord in adult macaque monkeys: Effects of an antibody treatment neutralizing Nogo-A. Brain Res 2008; 1217:96-109. [DOI: 10.1016/j.brainres.2007.11.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Accepted: 11/02/2007] [Indexed: 10/22/2022]
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19
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Al-Izki S, Kirkwood PA, Lemon RN, Enríquez Denton M. Electrophysiological actions of the rubrospinal tract in the anaesthetised rat. Exp Neurol 2008; 212:118-31. [PMID: 18501352 DOI: 10.1016/j.expneurol.2008.03.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Revised: 03/06/2008] [Accepted: 03/12/2008] [Indexed: 10/22/2022]
Abstract
The rubrospinal tract (RST) of the rat is widely used in studies of regeneration and plasticity, but the electrophysiology of its spinal actions has not been described. In anaesthetised rats with neuromuscular blockade, a tungsten microelectrode was located in the region of the red nucleus (RN) by combining stereotaxis with recording of antidromic potentials evoked from the contralateral spinal cord. Single stimuli through this electrode typically elicited two descending volleys in the contralateral dorsolateral funiculus (DLF) separated by about 1 ms, and one volley recorded from the ipsilateral DLF. Latencies of the ipsilateral and the early contralateral volley were similar. The activation of these volleys depended on the location of the stimulation site in or near the RN. Evidence is adduced to show that: (a) the late contralateral volley is carried by fibres of RST neurones, synaptically activated; (b) the early contralateral volley is mostly carried by RST fibres stimulated directly; (c) the ipsilateral volley is sometimes carried by RST fibres from the RN on the side contralateral to the stimulus; (d) otherwise, either early volley may derive from fibres in other tracts. Synaptic potentials related to the volleys were recorded within the cervical enlargement and their distribution plotted on cross-sections of the spinal cord. These measurements suggest that the great majority of RST terminations are on interneurones in the intermediate region contralateral to the RN. Direct synaptic actions on motoneurones are likely to be weak. Stimulation parameters appropriate for specific activation of the RST in future studies are suggested.
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Affiliation(s)
- Sarah Al-Izki
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, Queen Square, London WC1N 3BG, United Kingdom
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Lu J, Zheng YL, Wu DM, Luo L, Sun DX, Shan Q. Ursolic acid ameliorates cognition deficits and attenuates oxidative damage in the brain of senescent mice induced by D-galactose. Biochem Pharmacol 2007; 74:1078-90. [PMID: 17692828 DOI: 10.1016/j.bcp.2007.07.007] [Citation(s) in RCA: 219] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Revised: 07/01/2007] [Accepted: 07/02/2007] [Indexed: 11/23/2022]
Abstract
Ursolic acid (UA), a pentracyclic triterpene, is reported to have an antioxidant activity. Here we assessed the protective effect of UA against the d-galactose (D-gal)-induced neurotoxicity. We found that UA markedly reversed the D-gal induced learning and memory impairment by behavioral tests. The following antioxidant defense enzymes were measured: superoxide dismutases (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR). The content of the lipid peroxidation product malondialdehyde (MDA) was also analyzed. Our results indicated that the neuroprotective effect of UA against D-gal induced neurotoxicity might be caused, at least in part, by the increase in the activity of antioxidant enzymes with a reduction in lipid peroxidation. And UA also inhibited the activation of caspase-3 induced by D-gal. Furthermore, we found that UA significantly increased the level of growth-associated protein GAP43 in the brain of D-gal-treated mice. These results suggest that the pharmacological action of UA may offer a novel therapeutic strategy for the treatment of age-related conditions.
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Affiliation(s)
- Jun Lu
- Key Laboratory for Biotechnology on Medicinal Plants of Jiangsu Province, Xuzhou Normal University, Xuzhou 221116, PR China
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21
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Kwon BK, Liu J, Lam C, Plunet W, Oschipok LW, Hauswirth W, Di Polo A, Blesch A, Tetzlaff W. Brain-derived neurotrophic factor gene transfer with adeno-associated viral and lentiviral vectors prevents rubrospinal neuronal atrophy and stimulates regeneration-associated gene expression after acute cervical spinal cord injury. Spine (Phila Pa 1976) 2007; 32:1164-73. [PMID: 17495772 DOI: 10.1097/brs.0b013e318053ec35] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Experimental animal study. OBJECTIVE To determine if viral vectors carrying the gene for brain-derived neurotrophic factor (BDNF) could be used to promote an axonal regenerative response in rubrospinal neurons after an acute cervical spinal cord injury. SUMMARY OF BACKGROUND DATA Following axotomy in the cervical spinal cord, rubrospinal neurons undergo severe atrophy and fail to up-regulate important genes for regeneration. This can be attenuated or reversed with the infusion of BDNF to the injured cell bodies. This infusion technique, however, causes substantial parenchymal damage around the red nucleus and is limited by occlusion of the infusion pumps. This study examined whether viral vectors could be used to deliver the BDNF gene in a less damaging fashion and whether this could promote a regenerative response in injured rubrospinal neurons. METHODS Following a cervical spinal cord injury, the viral vectors were injected into the vicinity of the injured red nucleus. The extent of parenchymal damage around the red nucleus was assessed, as was the immunoreactivity to BDNF and cellular transfection patterns. Rubrospinal neuronal cross-sectional area was measured to determine if atrophy had been reversed, and in situ hybridization for GAP-43 and Talpha1 tubulin was performed to determine if there genes, which are important for axonal regeneration, were up-regulated. RESULTS Parenchymal damage associated with viral injection was significantly less than with previous infusion techniques. BDNF immunoreactivity around the red nucleus indicated that the BDNF transgene was expressed. Both viral vectors reversed rubrospinal neuronal atrophy and promoted the expression of GAP-43 and Talpha1 tubulin. CONCLUSIONS Viral-mediated transfer of the BDNF gene was successful at promoting a regenerative response in rubrospinal neurons following acute cervical spinal cord injury, with significantly less parenchymal damage than previously observed when infusing the BDNF protein.
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Affiliation(s)
- Brian K Kwon
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
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22
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Vaidla E, Talvik I, Kulla A, Sibul H, Maasalu K, Metsvaht T, Piirsoo A, Talvik T. Neonatal spinal muscular atrophy type 1 with bone fractures and heart defect. J Child Neurol 2007; 22:67-70. [PMID: 17608308 DOI: 10.1177/0883073807299954] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The authors present the case of an infant girl with severe generalized weakness, multiple bone fractures, and heart defect. She needed mechanical ventilation from birth. Radiographs showed mid-diaphyseal fractures of both humeri and of the right femur as well as generalized osteopenia. Electroneuromyography showed spontaneous fibrillations at rest with no active movements. Motor response to a stimulus could not be registered. A systolic heart murmur was detected, and echocardiography showed a large atrial septal defect and an additional membrane in the left atrium. DNA analysis confirmed the diagnosis of spinal muscular atrophy on the third day of life. Histology of the muscle showed both hypertrophic and atrophic fibers. Degenerating swollen neurons were found in the ventral horns of the spinal cord and also in the mesencephalic red nucleus, which has not been described before. Humeral bone showed only partly formed cortical bone. The spectrum of spinal muscular atrophy is very diverse, and atypical clinical findings do not always rule out 5q spinal muscular atrophy. The SMN1 gene should still be investigated.
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Affiliation(s)
- Eve Vaidla
- Department of Pediatrics, Tartu University, 6 Lunini Street, Tartu 51014, Estonia
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Abstract
Spinal cord injury (SCI) can lead to paraplegia or quadriplegia. Although there are no fully restorative treatments for SCI, various rehabilitative, cellular and molecular therapies have been tested in animal models. Many of these have reached, or are approaching, clinical trials. Here, we review these potential therapies, with an emphasis on the need for reproducible evidence of safety and efficacy. Individual therapies are unlikely to provide a panacea. Rather, we predict that combinations of strategies will lead to improvements in outcome after SCI. Basic scientific research should provide a rational basis for tailoring specific combinations of clinical therapies to different types of SCI.
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Affiliation(s)
- Sandrine Thuret
- Centre for the Cellular Basis of Behaviour, Institute of Psychiatry, King's College London, P.O. Box 39, 1-2 WW Ground, Denmark Hill, London SE5 8AF, UK
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Harvey AR, Hu Y, Leaver SG, Mellough CB, Park K, Verhaagen J, Plant GW, Cui Q. Gene therapy and transplantation in CNS repair: The visual system. Prog Retin Eye Res 2006; 25:449-89. [PMID: 16963308 DOI: 10.1016/j.preteyeres.2006.07.002] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Normal visual function in humans is compromised by a range of inherited and acquired degenerative conditions, many of which affect photoreceptors and/or retinal pigment epithelium. As a consequence the majority of experimental gene- and cell-based therapies are aimed at rescuing or replacing these cells. We provide a brief overview of these studies, but the major focus of this review is on the inner retina, in particular how gene therapy and transplantation can improve the viability and regenerative capacity of retinal ganglion cells (RGCs). Such studies are relevant to the development of new treatments for ocular conditions that cause RGC loss or dysfunction, for example glaucoma, diabetes, ischaemia, and various inflammatory and neurodegenerative diseases. However, RGCs and associated central visual pathways also serve as an excellent experimental model of the adult central nervous system (CNS) in which it is possible to study the molecular and cellular mechanisms associated with neuroprotection and axonal regeneration after neurotrauma. In this review we present the current state of knowledge pertaining to RGC responses to injury, neurotrophic and gene therapy strategies aimed at promoting RGC survival, and how best to promote the regeneration of RGC axons after optic nerve or optic tract injury. We also describe transplantation methods being used in attempts to replace lost RGCs or encourage the regrowth of RGC axons back into visual centres in the brain via peripheral nerve bridges. Cooperative approaches including novel combinations of transplantation, gene therapy and pharmacotherapy are discussed. Finally, we consider a number of caveats and future directions, such as problems associated with compensatory sprouting and the reformation of visuotopic maps, the need to develop efficient, regulatable viral vectors, and the need to develop different but sequential strategies that target the cell body and/or the growth cone at appropriate times during the repair process.
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Affiliation(s)
- Alan R Harvey
- School of Anatomy and Human Biology, The University of Western Australia, Crawley, WA 6009, Australia
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25
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Lynskey JV, Sandhu FA, Sandhu FA, Dai HN, Dai HN, McAtee M, Slotkin JR, Slotkin JR, MacArthur L, Bregman BS. Delayed intervention with transplants and neurotrophic factors supports recovery of forelimb function after cervical spinal cord injury in adult rats. J Neurotrauma 2006; 23:617-34. [PMID: 16689666 DOI: 10.1089/neu.2006.23.617] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The adult central nervous system is capable of considerable anatomical reorganization and functional recovery after injury. Functional outcomes, however, vary greatly, depending upon size and location of injury, type and timing of intervention, and type of recovery and plasticity evaluated. The present study was undertaken to assess the recovery of skilled and unskilled forelimb function in adult rats after a C5/C6 spinal cord over-hemisection and delayed intervention with fetal spinal cord transplants and neurotrophins. Recovery of forelimb function was evaluated during both target reaching (a skilled behavior) and vertical exploration (an unskilled behavior). Anatomical tracing and immunohistochemistry were used to assess the growth of descending raphespinal, corticospinal, and rubrospinal fibers at the injury site, tracts that normally confer forelimb function. Delayed intervention with transplants and either brain-derived neurotrophic factor (BDNF) or neurotrophin-3 (NT-3) restored skilled left forelimb reaching to pre-injury levels. Animals showed recovery of normal reaching movements rather than compensation with abnormal movements. Transplants and NT-3 also improved right forelimb use during an unskilled vertical exploration, but not skilled right reaching. Intervention with fetal transplant tissue supported the growth of descending serotonergic, corticospinal, and rubrospinal fibers into the transplant at the lesion site. The addition of neurotrophins, however, did not significantly increase axonal growth at the lesion site. These studies suggest that the recovery of skilled and unskilled forelimb use is possible after a large cervical spinal cord injury following delayed intervention with fetal spinal cord and neurotrophins. Plasticity of both spared and axotomized descending pathways likely contributes to the functional recovery observed.
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Affiliation(s)
- James V Lynskey
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC 20007, USA
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26
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Hagg T, Oudega M. Degenerative and spontaneous regenerative processes after spinal cord injury. J Neurotrauma 2006; 23:264-80. [PMID: 16629615 DOI: 10.1089/neu.2006.23.263] [Citation(s) in RCA: 203] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Spinal cord injury results in acute as well as progressive secondary destruction of local and distant nervous tissue through a number of degenerative mechanisms. Spinal cord injury also initiates a number of endogenous neuroprotective and regenerative responses. Understanding of these mechanisms might identify potential targets for treatments after spinal cord injury in humans. Here, we first discuss recent developments in our understanding of the immediate traumatic and subsequent secondary degeneration of local tissue and long projecting pathways in animal models. These include the inflammatory and vascular responses during the acute phase, as well as cell death, demyelination and scar formation in the subacute and chronic phases. Secondly, we discuss the spontaneous axonal regeneration of injured and plasticity of uninjured systems, and other repair-related responses in animals, including the upregulation of regeneration-associated genes in some neurons, increases in neurotrophic factors in the spinal cord and remyelination by oligodendrocyte precursors and invading Schwann cells. Lastly, we comment on the still limited understanding of the neuropathology in humans, which is largely similar to that in rodents. However, there also are potentially important differences, including the reduced glial scarring, inflammation and demyelination, the increased Schwannosis and the protracted Wallerian degeneration in humans. The validity of current rodent models for human spinal cord injury is also discussed. The emphasis of this review is on the literature from 2002 to early 2005.
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Affiliation(s)
- Theo Hagg
- Kentucky Spinal Cord Injury Research Center, Department of Neurological Surgery, University of Louisville, Louisville, Kentucky 40292, USA.
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Zhou LH, Wu W. Survival of Injured Spinal Motoneurons in Adult Rat upon Treatment with Glial Cell Line–Derived Neurotrophic Factor at 2 Weeks but Not at 4 Weeks after Root Avulsion. J Neurotrauma 2006; 23:920-7. [PMID: 16774476 DOI: 10.1089/neu.2006.23.920] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
We conducted a study of whether treatment with glial cell line-derived neurotrophic factor (GDNF) initiated at 2 or 4 weeks after spinal-root avulsion could promote survival and regulate neuronal nitric oxide synthase (nNOS) expression in adult rat spinal motoneurons. By 6 weeks after root avulsion, the treatment given at 2 weeks not only increased motoneuron survival (86.1% vs. 27.9%), but also reversed the atrophy of injured motoneurons and increased their somatic size (101.3% vs. 52.9%) in comparison to the untreated control group of animals. All surviving motoneurons in the GDNF-treated group showed immunoreactivity for choline acetyltransferase. In contrast, GDNF treatment at 4 weeks post-injury failed to promote motoneuron survival (33.1% vs. 27.9%) at 6 weeks compared to the control group. Both the 2- and 4-week post-injury treatments downregulated nNOS expression. This finding suggests that injured adult motoneurons die shortly (a few weeks in the rat) after root avulsion injury, but can be saved from degeneration by treatment within the proper time frame after injury, which in the case of GDNF treatment in rats, appears to be within 2 weeks of the avulsion injury of the spinal root. These findings provide useful information for choosing the best time frame for the potential clinical treatment of brachial plexus avulsion.
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Affiliation(s)
- Li-Hua Zhou
- Department of Anatomy, Zhong Shan Medical College, Sun Yat-sen University, Guangzhou, Guangzhou, China
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28
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Deumens R, Koopmans GC, Joosten EAJ. Regeneration of descending axon tracts after spinal cord injury. Prog Neurobiol 2005; 77:57-89. [PMID: 16271433 DOI: 10.1016/j.pneurobio.2005.10.004] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2005] [Revised: 08/23/2005] [Accepted: 10/05/2005] [Indexed: 02/03/2023]
Abstract
Axons within the adult mammalian central nervous system do not regenerate spontaneously after injury. Upon injury, the balance between growth promoting and growth inhibitory factors in the central nervous system dramatically changes resulting in the absence of regeneration. Axonal responses to injury vary considerably. In central nervous system regeneration studies, the spinal cord has received a lot of attention because of its relatively easy accessibility and its clinical relevance. The present review discusses the axon-tract-specific requirements for regeneration in the rat. This knowledge is very important for the development and optimalization of therapies to repair the injured spinal cord.
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Affiliation(s)
- Ronald Deumens
- Department of Psychiatry and Neuropsychology, Division Neuroscience, European Graduate School of Neuroscience EURON, University of Maastricht, Maastricht, The Netherlands.
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29
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Kwon BK, Fisher CG, Dvorak MF, Tetzlaff W. Strategies to promote neural repair and regeneration after spinal cord injury. Spine (Phila Pa 1976) 2005; 30:S3-13. [PMID: 16138063 DOI: 10.1097/01.brs.0000175186.17923.87] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Retrospective review of current literature regarding neuroprotection and axonal regeneration therapies for acute spinal cord injury. OBJECTIVES To provide an update for spine clinicians of the emerging therapeutic strategies for promoting neural repair and regeneration after spinal cord injury. SUMMARY OF BACKGROUND DATA The neuroscientific community has generated a number of novel potential treatments for spinal injuries, some of which have entered clinical trials. Clinicians who manage spinal cord trauma are likely to encounter patients and their families who have questions or wish to be involved in these emerging treatments. METHODS Literature review, with particular focus on currently used medications that may have neuroprotective potential in spinal cord injury, and axonal regeneration strategies that are emerging in preliminary human clinical trials. RESULTS A number of medications such as erythropoietin and minocycline have demonstrated neuroprotective properties in animal models of spinal cord injury, and their long-established safety in humans make them appealing candidates for clinical trials. Human experience with novel neuroprotective and axonal regeneration strategies is growing around the world, and the peer-reviewed reporting of this is anxiously awaited. CONCLUSIONS The initiation of human clinical trials for spinal cord-injured patients heralds great hope that effective therapies will be forthcoming, although a great deal remains to be learned. Clinicians must provide leadership in the epidemiologic design and rigor of these initial forays into human evaluation.
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Affiliation(s)
- Brian K Kwon
- Division of Spine, Department of Orthopaedics, International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada.
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30
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Dusart I, Ghoumari A, Wehrle R, Morel MP, Bouslama-Oueghlani L, Camand E, Sotelo C. Cell death and axon regeneration of Purkinje cells after axotomy: challenges of classical hypotheses of axon regeneration. ACTA ACUST UNITED AC 2005; 49:300-16. [PMID: 16111558 DOI: 10.1016/j.brainresrev.2004.11.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2004] [Revised: 11/16/2004] [Accepted: 11/24/2004] [Indexed: 12/11/2022]
Abstract
Although adult mammalian neurons are able to regenerate their axons in the peripheral nervous system under certain conditions, they are not able to do it in the central nervous system. The environment surrounding the severed axons appears to be a key factor for axon regeneration. Many studies aiming to enhance axon regeneration in the CNS of adult mammals have successfully manipulated this environment by adding growth permissive molecules and/or neutralizing growth inhibitory molecules. In both cases, the number of axons able to regenerate was low and the different neuronal populations were not equal in their regenerative response, suggesting that manipulation of the environment is not always sufficient. This is particularly well illustrated in the cerebellar system, in which axotomized inferior olivary neurons regenerate when confronted with a permissive environment, whereas mature Purkinje cells do not. The intrinsic ability of a neuron to regenerate its axon is generally correlated with the intensity of its reaction to axotomy (expression of molecules, probability to die). Furthermore, molecules such as GAP-43 (growth-associated molecule) and c-Jun are involved in both axon regeneration and cell death suggesting that these two processes are linked. Surprisingly, Purkinje cells lose their capacity to regenerate their axon (even in the absence of myelin) during development before losing their capacity to react to an axotomy by cell death. These results emphasize the different reactions to axotomy between neuron types and underline that in Purkinje cells, the two cell decisions (axon regeneration and cell death) are differently regulated and therefore not part of the same signaling pathway.
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Affiliation(s)
- I Dusart
- UMR-7102, Université Pierre et Marie Curie, 9 Quai Saint Bernard, 75005 Paris, France.
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31
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Ramer LM, Ramer MS, Steeves JD. Setting the stage for functional repair of spinal cord injuries: a cast of thousands. Spinal Cord 2005; 43:134-61. [PMID: 15672094 DOI: 10.1038/sj.sc.3101715] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Here we review mechanisms and molecules that necessitate protection and oppose axonal growth in the injured spinal cord, representing not only a cast of villains but also a company of therapeutic targets, many of which have yet to be fully exploited. We next discuss recent progress in the fields of bridging, overcoming conduction block and rehabilitation after spinal cord injury (SCI), where several treatments in each category have entered the spotlight, and some are being tested clinically. Finally, studies that combine treatments targeting different aspects of SCI are reviewed. Although experiments applying some treatments in combination have been completed, auditions for each part in the much-sought combination therapy are ongoing, and performers must demonstrate robust anatomical regeneration and/or significant return of function in animal models before being considered for a lead role.
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Affiliation(s)
- L M Ramer
- ICORD (International Collaboration on Repair Discoveries), The University of British Columbia, Vancouver, BC, Canada
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