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Sun X, Liu H, Tan Z, Hou Y, Pang M, Chen S, Xiao L, Yuan Q, Liu B, Rong L, He L. Remodeling Microenvironment for Endogenous Repair through Precise Modulation of Chondroitin Sulfate Proteoglycans Following Spinal Cord Injury. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2205012. [PMID: 36398653 DOI: 10.1002/smll.202205012] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 10/17/2022] [Indexed: 06/16/2023]
Abstract
The fluid-filled cystic cavity sealed by a dense scar developed following traumatic spinal cord injury (SCI) has been a major obstacle to neural regeneration and functional recovery. Here the transected lesion is bridged using a functional self-assembling peptide (F-SAP) hydrogel loaded with membrane-permeable intracellular sigma peptide (ISP) and intracellular LAR peptide (ILP), targeted at perturbing chondroitin sulfate proteoglycan (CSPG) inhibitory signaling. As compared to F-SAP hydrogel loaded with chondroitinase ABC, the F-SAP+ISP/ILP promotes a beneficial anti-inflammatory response via manipulation of microglia/macrophages infiltration and assembly of extracellular matrix (ECM) molecules into fibrotic matrix rather than scarring tissues. The remodeled ECM creates a permissive environment that supports axon regrowth and the formation of synaptic connections with neurons derived from endogenous neural stem cells. The remodeled networks contribute to functional recovery, as demonstrated by improved hind limb movements and electrophysiological properties. This work proposes a unique mechanism that ECM remodeling induced by CSPG-manipulation-based anti-inflammation can construct a permissive environment for neural regeneration, and shed light on the advancement of manipulation of cascading cellular and molecular events potential for endogenous repair of SCI.
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Affiliation(s)
- Xiumin Sun
- Department of Spine Surgery, The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510630, China
| | - Haiqian Liu
- Joint International Research Laboratory of CNS Regeneration Ministry of Education, Guangdong-Hong Kong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, 510623, China
- School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Zan Tan
- Department of Spine Surgery, The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510630, China
| | - Yuhui Hou
- Department of Spine Surgery, The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510630, China
| | - Mao Pang
- Department of Spine Surgery, The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510630, China
| | - Shengfeng Chen
- Joint International Research Laboratory of CNS Regeneration Ministry of Education, Guangdong-Hong Kong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, 510623, China
| | - Longyou Xiao
- Department of Spine Surgery, The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510630, China
| | - Qiuju Yuan
- Centre of Regenerative Medicine and Health, Hong Kong Institute of Science & Innovation, Chinese Academy of Sciences, Hong Kong, 999077, China
| | - Bin Liu
- Department of Spine Surgery, The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510630, China
| | - Limin Rong
- Department of Spine Surgery, The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510630, China
| | - Liumin He
- Department of Spine Surgery, The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510630, China
- Joint International Research Laboratory of CNS Regeneration Ministry of Education, Guangdong-Hong Kong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, 510623, China
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Chemistry and Function of Glycosaminoglycans in the Nervous System. ADVANCES IN NEUROBIOLOGY 2023; 29:117-162. [DOI: 10.1007/978-3-031-12390-0_5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Estrada V, Oldenburg E, Popa O, Muller HW. Mapping the long rocky road to effective spinal cord injury therapy - A meta-review of pre-clinical and clinical research. J Neurotrauma 2022; 39:591-612. [PMID: 35196894 DOI: 10.1089/neu.2021.0298] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Spinal cord injury (SCI) is a rare condition, which even after decades of research, to date still presents an incurable condition with a complex symptomatology. SCI can result in paralysis, pain, loss of sensation, bladder and sexual dysfunction, and muscle degeneration to name but a few. The large number of publications makes it difficult to keep track of current progress in the field and of the many treatment options, which have been suggested and are being proposed with increasing frequency. Scientific databases with user-oriented search options will offer possible solutions, but they are still mostly in the development phase. In this meta-analysis, we summarize and narrow down SCI therapeutic approaches applied in pre-clinical and clinical research. Statistical analyses of treatment clusters - assorted after counting annual publication numbers in PubMed and ClinicalTrials.gov databases - were performed to allow the comparison of research foci and of their translation efficacy into clinical therapy. Using the example of SCI research, our findings demonstrate the challenges that come with the accelerating research progress - an issue, which many research fields are faced with today. The analyses point out similarities and differences in the prioritization of SCI research in pre-clinical versus clinical therapy strategies. Moreover, the results demonstrate the rapidly growing importance of modern (bio-)engineering technologies.
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Affiliation(s)
- Veronica Estrada
- Heinrich Heine University Düsseldorf, 9170, Neurology, Molecular Neurobiology Laboratory, Düsseldorf, Germany;
| | - Ellen Oldenburg
- Heinrich Heine University Düsseldorf, 9170, Institute of Quantitative and Theoretical Biology, Düsseldorf, Germany;
| | - Ovidiu Popa
- Heinrich Heine University Düsseldorf, 9170, Institute of Quantitative and Theoretical Biology, Düsseldorf, Germany;
| | - Hans W Muller
- Heinrich Heine University Düsseldorf, 9170, Neurology, Düsseldorf, Germany;
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Suzuki H, Imajo Y, Funaba M, Nishida N, Sakamoto T, Sakai T. Current Concepts of Neural Stem/Progenitor Cell Therapy for Chronic Spinal Cord Injury. Front Cell Neurosci 2022; 15:794692. [PMID: 35185471 PMCID: PMC8850278 DOI: 10.3389/fncel.2021.794692] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 12/20/2021] [Indexed: 11/13/2022] Open
Abstract
Chronic spinal cord injury (SCI) is a devastating condition that results in major neurological deficits and social burden. It continues to be managed symptomatically, and no real therapeutic strategies have been devised for its treatment. Neural stem/neural progenitor cells (NSCs/NPCs) being used for the treatment of chronic SCI in experimental SCI models can not only replace the lost cells and remyelinate axons in the injury site but also support their growth and provide neuroprotective factors. Currently, several clinical studies using NSCs/NPCs are underway worldwide. NSCs/NPCs also have the potential to differentiate into all three neuroglial lineages to regenerate neural circuits, demyelinate denuded axons, and provide trophic support to endogenous cells. This article explains the challenging pathophysiology of chronic SCI and discusses key NSC/NPC-based techniques having the greatest potential for translation over the next decade.
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Lucas-Osma AM, Schmidt EKA, Vavrek R, Bennett DJ, Fouad K, Fenrich KK. Rehabilitative training improves skilled forelimb motor function after cervical unilateral contusion spinal cord injury in rats. Behav Brain Res 2021; 422:113731. [PMID: 34979221 DOI: 10.1016/j.bbr.2021.113731] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 12/14/2021] [Accepted: 12/29/2021] [Indexed: 11/16/2022]
Abstract
Animal models of cervical spinal cord injury (SCI) have frequently utilized partial transection injuries to evaluate plasticity promoting treatments such as rehabilitation training of skilled reaching and grasping tasks. Though highly useful for studying the effects of cutting specific spinal tracts that are important for skilled forelimb motor function, cervical partial-transection SCI-models underappreciate the extensive spread of most human SCIs, thus offering poor predictability for the clinical setting. Conversely, moderate cervical contusion SCI models targeting the spinal tracts important for skilled reaching and grasping can better replicate the increased size of most human SCIs and are often considered more clinically relevant. However, it is unknown whether animals with moderate cervical contusion SCIs that damage key spinal motor tracts can train in skilled reaching and grasping tasks. In this study, we quantify the impact of injury size and distribution on recovery in a skilled motor task called the single pellet reaching, grasping and retrieval (SPRGR) task in rats with cervical unilateral contusion injuries (UCs), and compare to rats with a partial transection SCIs (i.e., dorsolateral quadrant transection; DLQ). We found that UCs damage key tracts important for performing skilled motor tasks, similar to DLQs, but UCs also produce more extensive grey matter damage and more ventral white matter damage than DLQs. We also compared forelimb functionality at 1, 3, and 5 weeks of rehabilitative motor training between trained and untrained rats and found a more severe drop in SPRGR performance than in DLQ SCIs. Nevertheless, despite more severe injuries and initially low SPRGR performance, rehabilitative training for contusion animals resulted in significant improvements in SPRGR performance and proportionally more recovery than DLQ rats. Our findings show that rehabilitative motor training can facilitate considerable amounts of motor recovery despite extensive spinal cord damage, especially grey matter damage, thus supporting the use of contusion or compression SCI models and showing that ventral grey and white matter damage are not necessarily detrimental to recovery after training.
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Affiliation(s)
- Ana M Lucas-Osma
- Neuroscience and Mental Health Institute, University of Alberta; Edmonton, Alberta, Canada; Faculty of Rehabilitation Medicine, University of Alberta; Edmonton, Alberta, Canada
| | - Emma K A Schmidt
- Neuroscience and Mental Health Institute, University of Alberta; Edmonton, Alberta, Canada; Faculty of Rehabilitation Medicine, University of Alberta; Edmonton, Alberta, Canada; Department of Physical Therapy, University of Alberta; Edmonton, Alberta, Canada
| | - Romana Vavrek
- Neuroscience and Mental Health Institute, University of Alberta; Edmonton, Alberta, Canada; Faculty of Rehabilitation Medicine, University of Alberta; Edmonton, Alberta, Canada; Department of Physical Therapy, University of Alberta; Edmonton, Alberta, Canada
| | - David J Bennett
- Neuroscience and Mental Health Institute, University of Alberta; Edmonton, Alberta, Canada; Faculty of Rehabilitation Medicine, University of Alberta; Edmonton, Alberta, Canada
| | - Karim Fouad
- Neuroscience and Mental Health Institute, University of Alberta; Edmonton, Alberta, Canada; Faculty of Rehabilitation Medicine, University of Alberta; Edmonton, Alberta, Canada; Department of Physical Therapy, University of Alberta; Edmonton, Alberta, Canada
| | - Keith K Fenrich
- Neuroscience and Mental Health Institute, University of Alberta; Edmonton, Alberta, Canada; Faculty of Rehabilitation Medicine, University of Alberta; Edmonton, Alberta, Canada.
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Li C, Sahu S, Kou G, Jagadeesan N, Joseph TP, Li Lin S, Schachner M. Chondroitin 6-sulfate-binding peptides improve recovery in spinal cord-injured mice. Eur J Pharmacol 2021; 910:174421. [PMID: 34391768 DOI: 10.1016/j.ejphar.2021.174421] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 08/01/2021] [Accepted: 08/11/2021] [Indexed: 02/05/2023]
Abstract
The role of glycosaminoglycan sulfation patterns, particularly in regard to scar formation and inhibition of neuritogenesis, has been mainly studied in cell culture with a focus on chondroitin 4-sulfate. In this study, we investigated chondroitin 6-sulfate (C6S) and found that it also inhibits neurite outgrowth of mouse cerebellar granule neurons in vitro. To examine whether the inhibitory activity of C6S could be neutralized, seven previously characterized high-affinity C6S-binding peptides were tested, among which three peptides neutralized the inhibitory functions of C6S. We further investigated these peptides in a mouse model of spinal cord injury, since upregulation of C6S expression in the glial scar following injury has been associated with reduced axonal regrowth and functional recovery. We here subjected mice to severe compression injury at thoracic levels T7-T9, immediately followed by inserting gelfoam patches soaked in C6S-binding peptides or in a control peptide. Application of C6S-binding peptides led to functional recovery after injury and prevented fibrotic glial scar formation, as seen by decreased activation of astrocytes and microglia/macrophages. Decreased expression of several lecticans and deposition of fibronectin at the site of injury were also observed. Application of C6S-binding peptides led to axonal regrowth and inhibited the C6S-mediated activation of RhoA/ROCK and decrease of PI3K-Akt-mTOR signaling pathways. Taken together, these results indicate that treatment with C6S-binding peptides improves functional recovery in a mouse model of spinal cord injury.
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Affiliation(s)
- Caijie Li
- Center for Neuroscience, Shantou University Medical College, Shantou, Guangdong 515041, China
| | - Sudhanshu Sahu
- Center for Neuroscience, Shantou University Medical College, Shantou, Guangdong 515041, China
| | - Guanhua Kou
- Center for Neuroscience, Shantou University Medical College, Shantou, Guangdong 515041, China
| | - Nataraj Jagadeesan
- Center for Neuroscience, Shantou University Medical College, Shantou, Guangdong 515041, China
| | - Thomson Patrick Joseph
- Center for Neuroscience, Shantou University Medical College, Shantou, Guangdong 515041, China
| | - Stanley Li Lin
- Department of Cell Biology, Shantou University Medical College, Shantou, China; Guangdong Provincial Key Laboratory for Breast Cancer Diagnosis and Treatment, Shantou University Medical College, Shantou, China
| | - Melitta Schachner
- Center for Neuroscience, Shantou University Medical College, Shantou, Guangdong 515041, China; Keck Center for Collaborative Neuroscience and Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ, 08854, USA.
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Hart CG, Karimi-Abdolrezaee S. Recent insights on astrocyte mechanisms in CNS homeostasis, pathology, and repair. J Neurosci Res 2021; 99:2427-2462. [PMID: 34259342 DOI: 10.1002/jnr.24922] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 06/06/2021] [Accepted: 06/24/2021] [Indexed: 12/20/2022]
Abstract
Astrocytes play essential roles in development, homeostasis, injury, and repair of the central nervous system (CNS). Their development is tightly regulated by distinct spatial and temporal cues during embryogenesis and into adulthood throughout the CNS. Astrocytes have several important responsibilities such as regulating blood flow and permeability of the blood-CNS barrier, glucose metabolism and storage, synapse formation and function, and axon myelination. In CNS pathologies, astrocytes also play critical parts in both injury and repair mechanisms. Upon injury, they undergo a robust phenotypic shift known as "reactive astrogliosis," which results in both constructive and deleterious outcomes. Astrocyte activation and migration at the site of injury provides an early defense mechanism to minimize the extent of injury by enveloping the lesion area. However, astrogliosis also contributes to the inhibitory microenvironment of CNS injury and potentiate secondary injury mechanisms, such as inflammation, oxidative stress, and glutamate excitotoxicity, which facilitate neurodegeneration in CNS pathologies. Intriguingly, reactive astrocytes are increasingly a focus in current therapeutic strategies as their activation can be modulated toward a neuroprotective and reparative phenotype. This review will discuss recent advancements in knowledge regarding the development and role of astrocytes in the healthy and pathological CNS. We will also review how astrocytes have been genetically modified to optimize their reparative potential after injury, and how they may be transdifferentiated into neurons and oligodendrocytes to promote repair after CNS injury and neurodegeneration.
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Affiliation(s)
- Christopher G Hart
- Department of Physiology and Pathophysiology, Spinal Cord Research Centre, Children's Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, MB, Canada
| | - Soheila Karimi-Abdolrezaee
- Department of Physiology and Pathophysiology, Spinal Cord Research Centre, Children's Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, MB, Canada
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Suzuki H, Sakai T. Current Concepts of Stem Cell Therapy for Chronic Spinal Cord Injury. Int J Mol Sci 2021; 22:ijms22147435. [PMID: 34299053 PMCID: PMC8308009 DOI: 10.3390/ijms22147435] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 07/08/2021] [Accepted: 07/09/2021] [Indexed: 12/14/2022] Open
Abstract
Chronic spinal cord injury (SCI) is a catastrophic condition associated with significant neurological deficit and social and financial burdens. It is currently being managed symptomatically with no real therapeutic strategies available. In recent years, a number of innovative regenerative strategies have emerged and have been continuously investigated in clinical trials. In addition, several more are coming down the translational pipeline. Among ongoing and completed trials are those reporting the use of mesenchymal stem cells, neural stem/progenitor cells, induced pluripotent stem cells, olfactory ensheathing cells, and Schwann cells. The advancements in stem cell technology, combined with the powerful neuroimaging modalities, can now accelerate the pathway of promising novel therapeutic strategies from bench to bedside. Various combinations of different molecular therapies have been combined with supportive scaffolds to facilitate favorable cell–material interactions. In this review, we summarized some of the most recent insights into the preclinical and clinical studies using stem cells and other supportive drugs to unlock the microenvironment in chronic SCI to treat patients with this condition. Successful future therapies will require these stem cells and other synergistic approaches to address the persistent barriers to regeneration, including glial scarring, loss of structural framework, and immunorejection.
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Li X, Li M, Tian L, Chen J, Liu R, Ning B. Reactive Astrogliosis: Implications in Spinal Cord Injury Progression and Therapy. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:9494352. [PMID: 32884625 PMCID: PMC7455824 DOI: 10.1155/2020/9494352] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 05/06/2020] [Accepted: 07/31/2020] [Indexed: 12/11/2022]
Abstract
Astrocytes are the most populous glial cells in the central nervous system (CNS). They are essential to CNS physiology and play important roles in the maintenance of homeostasis, development of synaptic plasticity, and neuroprotection. Nevertheless, under the influence of certain factors, astrocytes may also exert detrimental effects through a process of reactive astrogliosis. Previous studies have shown that astrocytes have more than one type of polarization. Two types have been extensively researched. One is a damaging change that occurs under inflammation and has been termed A1 astrocyte, while the other is a restorative change that occurs under ischemic induction and was termed A2 astrocyte. Researchers are now increasingly paying attention to the role of astrocytes in spinal cord injury (SCI), degenerative diseases, chronic pain, neurological tumors, and other CNS disorders. In this review, we discuss (a) the characteristics of polarized astrocytes, (b) the relationship between astrocyte polarization and SCI, and (c) new implications of reactive astrogliosis for future SCI therapies.
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Affiliation(s)
- Xinyu Li
- Jinan Central Hospital, Cheeloo College of Medicine, Shandong University, No. 105, Jiefang Road, Jinan, Shandong 250013, China
| | - Meng Li
- Jinan Central Hospital, Cheeloo College of Medicine, Shandong University, No. 105, Jiefang Road, Jinan, Shandong 250013, China
| | - Lige Tian
- Jinan Central Hospital, Cheeloo College of Medicine, Shandong University, No. 105, Jiefang Road, Jinan, Shandong 250013, China
| | - Jianan Chen
- Jinan Central Hospital, Cheeloo College of Medicine, Shandong University, No. 105, Jiefang Road, Jinan, Shandong 250013, China
| | - Ronghan Liu
- Jinan Central Hospital, Cheeloo College of Medicine, Shandong University, No. 105, Jiefang Road, Jinan, Shandong 250013, China
| | - Bin Ning
- Jinan Central Hospital, Cheeloo College of Medicine, Shandong University, No. 105, Jiefang Road, Jinan, Shandong 250013, China
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Benmelouka A, Shamseldin LS, Nourelden AZ, Negida A. A Review on the Etiology and Management of Pediatric Traumatic Spinal Cord Injuries. ADVANCED JOURNAL OF EMERGENCY MEDICINE 2019; 4:e28. [PMID: 32322796 PMCID: PMC7163256 DOI: 10.22114/ajem.v0i0.256] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
CONTEXT Pediatric traumatic spinal cord injury (SCI) is an uncommon presentation in the emergency department. Severe injuries are associated with devastating outcomes and complications, resulting in high costs to both the society and the economic system. EVIDENCE ACQUISITION The data on pediatric traumatic spinal cord injuries has been narratively reviewed. RESULTS Pediatric SCI is a life-threatening emergency leading to serious outcomes and high mortality in children if not managed promptly. Pediatric SCI can impose many challenges to neurosurgeons and caregivers because of the lack of large studies with high evidence level and specific guidelines in terms of diagnosis, initial management and of in-hospital treatment options. Several novel potential treatment options for SCI have been developed and are currently under investigation. However, research studies into this field have been limited by the ethical and methodological challenges. CONCLUSION Future research is needed to investigate the safety and efficacy of the recent uprising neurodegenerative techniques in SCI population. Owing to the current limitations, there is a need to develop novel trial methodologies that can overcome the current methodological and ethical limitations.
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Affiliation(s)
| | | | | | - Ahmed Negida
- Medical Research Group of Egypt, Egypt
- Faculty of Medicine, Zagazig University, Zagazig, Egypt
- Neurosurgery Department, Bahçeşehir University, Istanbul, Turkey
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Alizadeh A, Dyck SM, Karimi-Abdolrezaee S. Traumatic Spinal Cord Injury: An Overview of Pathophysiology, Models and Acute Injury Mechanisms. Front Neurol 2019; 10:282. [PMID: 30967837 PMCID: PMC6439316 DOI: 10.3389/fneur.2019.00282] [Citation(s) in RCA: 603] [Impact Index Per Article: 120.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 03/05/2019] [Indexed: 12/11/2022] Open
Abstract
Traumatic spinal cord injury (SCI) is a life changing neurological condition with substantial socioeconomic implications for patients and their care-givers. Recent advances in medical management of SCI has significantly improved diagnosis, stabilization, survival rate and well-being of SCI patients. However, there has been small progress on treatment options for improving the neurological outcomes of SCI patients. This incremental success mainly reflects the complexity of SCI pathophysiology and the diverse biochemical and physiological changes that occur in the injured spinal cord. Therefore, in the past few decades, considerable efforts have been made by SCI researchers to elucidate the pathophysiology of SCI and unravel the underlying cellular and molecular mechanisms of tissue degeneration and repair in the injured spinal cord. To this end, a number of preclinical animal and injury models have been developed to more closely recapitulate the primary and secondary injury processes of SCI. In this review, we will provide a comprehensive overview of the recent advances in our understanding of the pathophysiology of SCI. We will also discuss the neurological outcomes of human SCI and the available experimental model systems that have been employed to identify SCI mechanisms and develop therapeutic strategies for this condition.
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Affiliation(s)
- Arsalan Alizadeh
- Regenerative Medicine Program, Department of Physiology and Pathophysiology, Rady Faculty of Health Sciences, Spinal Cord Research Center, University of Manitoba, Winnipeg, MB, Canada
| | - Scott Matthew Dyck
- Regenerative Medicine Program, Department of Physiology and Pathophysiology, Rady Faculty of Health Sciences, Spinal Cord Research Center, University of Manitoba, Winnipeg, MB, Canada
| | - Soheila Karimi-Abdolrezaee
- Regenerative Medicine Program, Department of Physiology and Pathophysiology, Rady Faculty of Health Sciences, Spinal Cord Research Center, University of Manitoba, Winnipeg, MB, Canada
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Dyck S, Kataria H, Akbari-Kelachayeh K, Silver J, Karimi-Abdolrezaee S. LAR and PTPσ receptors are negative regulators of oligodendrogenesis and oligodendrocyte integrity in spinal cord injury. Glia 2018; 67:125-145. [PMID: 30394599 DOI: 10.1002/glia.23533] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Revised: 09/18/2018] [Accepted: 09/19/2018] [Indexed: 12/26/2022]
Abstract
Following spinal cord injury (SCI), the population of mature oligodendrocytes undergoes substantial cell death; promoting their preservation and replacement is a viable strategy for preserving axonal integrity and white matter repair in the injured spinal cord. Dramatic upregulation of matrix chondroitin sulfate proteoglycans (CSPGs) is shown to pose an obstacle to endogenous repair processes, and targeting CSPGs improves functional recovery after SCI. However, the cellular and molecular mechanisms underlying the inhibitory effects of CSPGs remain largely undefined. Modulation of CSPGs specific signaling receptors, leukocyte common antigen-related (LAR), and protein tyrosine phosphatase-sigma (PTPσ) allows us to uncover the role and mechanisms of CSPGs in regulating oligodendrocytes in SCI. Here, utilizing specific functionally blocking peptides in a clinically relevant model of contusive/compressive SCI in the rat, we demonstrate that inhibition of PTPσ and LAR receptors promotes oligodendrogenesis by endogenous precursor cells, attenuates caspase 3-mediated cell death in mature oligodendrocytes, and preserves myelin. In parallel in vitro systems, we have unraveled that CSPGs directly induce apoptosis in populations of neural precursor cells and oligodendrocyte progenitor cells and limit their ability for oligodendrocyte differentiation, maturation, and myelination. These negative effects of CSPGs are mediated through the activation of both LAR and PTPσ receptors and the downstream Rho/ROCK pathway. Thus, we have identified a novel inhibitory role for PTPσ and LAR in regulating oligodendrocyte differentiation and apoptosis in the injured adult spinal cord and a new feasible therapeutic strategy for optimizing endogenous cell replacement following SCI.
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Affiliation(s)
- Scott Dyck
- Department of Physiology and Pathophysiology, The Regenerative Medicine Program, The Spinal Cord Research Center, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Hardeep Kataria
- Department of Physiology and Pathophysiology, The Regenerative Medicine Program, The Spinal Cord Research Center, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Khashayar Akbari-Kelachayeh
- Department of Physiology and Pathophysiology, The Regenerative Medicine Program, The Spinal Cord Research Center, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Jerry Silver
- Department of Neuroscience, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Soheila Karimi-Abdolrezaee
- Department of Physiology and Pathophysiology, The Regenerative Medicine Program, The Spinal Cord Research Center, University of Manitoba, Winnipeg, Manitoba, Canada.,Children's Hospital Research Institute of Manitoba, Winnipeg, Manitoba, Canada
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Tran AP, Warren PM, Silver J. The Biology of Regeneration Failure and Success After Spinal Cord Injury. Physiol Rev 2018. [PMID: 29513146 DOI: 10.1152/physrev.00017.2017] [Citation(s) in RCA: 490] [Impact Index Per Article: 81.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Since no approved therapies to restore mobility and sensation following spinal cord injury (SCI) currently exist, a better understanding of the cellular and molecular mechanisms following SCI that compromise regeneration or neuroplasticity is needed to develop new strategies to promote axonal regrowth and restore function. Physical trauma to the spinal cord results in vascular disruption that, in turn, causes blood-spinal cord barrier rupture leading to hemorrhage and ischemia, followed by rampant local cell death. As subsequent edema and inflammation occur, neuronal and glial necrosis and apoptosis spread well beyond the initial site of impact, ultimately resolving into a cavity surrounded by glial/fibrotic scarring. The glial scar, which stabilizes the spread of secondary injury, also acts as a chronic, physical, and chemo-entrapping barrier that prevents axonal regeneration. Understanding the formative events in glial scarring helps guide strategies towards the development of potential therapies to enhance axon regeneration and functional recovery at both acute and chronic stages following SCI. This review will also discuss the perineuronal net and how chondroitin sulfate proteoglycans (CSPGs) deposited in both the glial scar and net impede axonal outgrowth at the level of the growth cone. We will end the review with a summary of current CSPG-targeting strategies that help to foster axonal regeneration, neuroplasticity/sprouting, and functional recovery following SCI.
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Affiliation(s)
- Amanda Phuong Tran
- Department of Neurosciences, Case Western Reserve University , Cleveland, Ohio ; and School of Biomedical Sciences, University of Leeds , Leeds , United Kingdom
| | - Philippa Mary Warren
- Department of Neurosciences, Case Western Reserve University , Cleveland, Ohio ; and School of Biomedical Sciences, University of Leeds , Leeds , United Kingdom
| | - Jerry Silver
- Department of Neurosciences, Case Western Reserve University , Cleveland, Ohio ; and School of Biomedical Sciences, University of Leeds , Leeds , United Kingdom
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Moon LDF. Chromatolysis: Do injured axons regenerate poorly when ribonucleases attack rough endoplasmic reticulum, ribosomes and RNA? Dev Neurobiol 2018; 78:1011-1024. [PMID: 30027624 PMCID: PMC6334169 DOI: 10.1002/dneu.22625] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 05/31/2018] [Accepted: 06/04/2018] [Indexed: 02/06/2023]
Abstract
After axonal injury, chromatolysis (fragmentation of Nissl substance) can occur in the soma. Electron microscopy shows that chromatolysis involves fission of the rough endoplasmic reticulum. In CNS neurons (which do not regenerate axons back to their original targets) or in motor neurons or dorsal root ganglion neurons denied axon regeneration (e.g., by transection and ligation), chromatolysis is often accompanied by degranulation (loss of ribosomes from rough endoplasmic reticulum), disaggregation of polyribosomes and degradation of monoribosomes into dust‐like particles. Ribosomes and rough endoplasmic reticulum may also be degraded in autophagic vacuoles by ribophagy and reticulophagy, respectively. In other words, chromatolysis is disruption of parts of the protein synthesis infrastructure. Whereas some neurons may show transient or no chromatolysis, severely injured neurons can remain chromatolytic and never again synthesize normal levels of protein; some may atrophy or die. Ribonuclease(s) might cause the following features of chromatolysis: fragmentation and degranulation of rough endoplasmic reticulum, disaggregation of polyribosomes and degradation of monoribosomes. For example, ribonucleases in the EndoU/PP11 family can modify rough endoplasmic reticulum; many ribonucleases can degrade mRNA causing polyribosomes to unchain and disperse, and they can disassemble monoribosomes; Ribonuclease 5 can control rRNA synthesis and degrade tRNA; Ribonuclease T2 can degrade ribosomes, endoplasmic reticulum and RNA within autophagic vacuoles; and Ribonuclease IRE1α acts as a stress sensor within the endoplasmic reticulum. Regeneration might be improved after axonal injury by protecting the protein synthesis machinery from catabolism; targeting ribonucleases using inhibitors can enhance neurite outgrowth and could be a profitable strategy in vivo. © 2018 Wiley Periodicals, Inc. Develop Neurobiol, 2018
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Affiliation(s)
- Lawrence David Falcon Moon
- Neurorestoration Group, Wolfson Centre for Age-Related Diseases, 16-20 Newcomen Street, London, SE1 1UL, United Kingdom
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Raspa A, Bolla E, Cuscona C, Gelain F. Feasible stabilization of chondroitinase abc enables reduced astrogliosis in a chronic model of spinal cord injury. CNS Neurosci Ther 2018; 25:86-100. [PMID: 29855151 DOI: 10.1111/cns.12984] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 05/03/2018] [Accepted: 05/04/2018] [Indexed: 11/30/2022] Open
Abstract
AIMS Usually, spinal cord injury (SCI) develops into a glial scar containing extracellular matrix molecules including chondroitin sulfate proteoglycans (CSPGs). Chondroitinase ABC (ChABC), from Proteus vulgaris degrading the glycosaminoglycan (GAG) side chains of CSPGs, offers the opportunity to improve the final outcome of SCI. However, ChABC usage is limited by its thermal instability, requiring protein structure modifications, consecutive injections at the lesion site, or implantation of infusion pumps. METHODS Aiming at more feasible strategy to preserve ChABC catalytic activity, we assessed various stabilizing agents in different solutions and demonstrated, via a spectrophotometric protocol, that the 2.5 mol/L Sucrose solution best stabilized ChABC as far as 14 days in vitro. RESULTS ChABC activity was improved in both stabilizing and diluted solutions at +37°C, that is, mimicking their usage in vivo. We also verified the safety of the proposed aqueous sucrose solution in terms of viability/cytotoxicity of mouse neural stem cells (NSCs) in both proliferating and differentiating conditions in vitro. Furthermore, we showed that a single intraspinal treatment with ChABC and sucrose reduced reactive gliosis at the injury site in chronic contusive SCI in rats and slightly enhanced their locomotor recovery. CONCLUSION Usage of aqueous sucrose solutions may be a feasible strategy, in combination with rehabilitation, to ameliorate ChABC-based treatments to promote the regeneration of central nervous system injuries.
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Affiliation(s)
- Andrea Raspa
- Opera di San Pio da Pietrelcina, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy
| | - Edoardo Bolla
- Center for Nanomedicine and Tissue Engineering (CNTE), A.O. Ospedale Niguarda Cà Granda, Piazza dell'Ospedale Maggiore, Milan, Italy
| | - Claudia Cuscona
- Center for Nanomedicine and Tissue Engineering (CNTE), A.O. Ospedale Niguarda Cà Granda, Piazza dell'Ospedale Maggiore, Milan, Italy
| | - Fabrizio Gelain
- Opera di San Pio da Pietrelcina, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy.,Center for Nanomedicine and Tissue Engineering (CNTE), A.O. Ospedale Niguarda Cà Granda, Piazza dell'Ospedale Maggiore, Milan, Italy
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Suzuki H, Ahuja CS, Salewski RP, Li L, Satkunendrarajah K, Nagoshi N, Shibata S, Fehlings MG. Neural stem cell mediated recovery is enhanced by Chondroitinase ABC pretreatment in chronic cervical spinal cord injury. PLoS One 2017; 12:e0182339. [PMID: 28771534 PMCID: PMC5542671 DOI: 10.1371/journal.pone.0182339] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 07/17/2017] [Indexed: 01/05/2023] Open
Abstract
Traumatic spinal cord injuries (SCIs) affect millions of people worldwide; the majority of whom are in the chronic phase of their injury. Unfortunately, most current treatments target the acute/subacute injury phase as the microenvironment of chronically injured cord consists of a well-established glial scar with inhibitory chondroitin sulfate proteoglycans (CSPGs) which acts as a potent barrier to regeneration. It has been shown that CSPGs can be degraded in vivo by intrathecal Chondroitinase ABC (ChABC) to produce a more permissive environment for regeneration by endogenous cells or transplanted neural stem cells (NSCs) in the subacute phase of injury. Using a translationally-relevant clip-contusion model of cervical spinal cord injury in mice we sought to determine if ChABC pretreatment could modify the harsh chronic microenvironment to enhance subsequent regeneration by induced pluripotent stem cell-derived NSCs (iPS-NSC). Seven weeks after injury—during the chronic phase—we delivered ChABC by intrathecal osmotic pump for one week followed by intraparenchymal iPS-NSC transplant rostral and caudal to the injury epicenter. ChABC administration reduced chronic-injury scar and resulted in significantly improved iPSC-NSC survival with clear differentiation into all three neuroglial lineages. Neurons derived from transplanted cells also formed functional synapses with host circuits on patch clamp analysis. Furthermore, the combined treatment led to recovery in key functional muscle groups including forelimb grip strength and measures of forelimb/hindlimb locomotion assessed by Catwalk. This represents important proof-of-concept data that the chronically injured spinal cord can be ‘unlocked’ by ChABC pretreatment to produce a microenvironment conducive to regenerative iPS-NSC therapy.
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Affiliation(s)
- Hidenori Suzuki
- Division of Genetics and Development, Krembil Research Institute, Toronto, Canada
- Department of Orthopedics Surgery, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Christopher S. Ahuja
- Division of Genetics and Development, Krembil Research Institute, Toronto, Canada
- Institute of Medical Science, University of Toronto, Toronto, Canada
- Division of Neurosurgery, University of Toronto, University of Toronto, Toronto, Canada
| | - Ryan P. Salewski
- Division of Genetics and Development, Krembil Research Institute, Toronto, Canada
- Institute of Medical Science, University of Toronto, Toronto, Canada
- Faculty of Medicine, University of Toronto, Toronto, Canada
| | - Lijun Li
- Division of Genetics and Development, Krembil Research Institute, Toronto, Canada
| | | | - Narihito Nagoshi
- Division of Genetics and Development, Krembil Research Institute, Toronto, Canada
- Department of Orthopedics Surgery, Keio University, Tokyo, Japan
| | | | - Michael G. Fehlings
- Division of Genetics and Development, Krembil Research Institute, Toronto, Canada
- Institute of Medical Science, University of Toronto, Toronto, Canada
- Division of Neurosurgery, University of Toronto, University of Toronto, Toronto, Canada
- Faculty of Medicine, University of Toronto, Toronto, Canada
- Spinal Program, University Health Network, Toronto Western Hospital, Toronto, Canada
- * E-mail:
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Ahuja CS, Fehlings M. Concise Review: Bridging the Gap: Novel Neuroregenerative and Neuroprotective Strategies in Spinal Cord Injury. Stem Cells Transl Med 2016; 5:914-24. [PMID: 27130222 DOI: 10.5966/sctm.2015-0381] [Citation(s) in RCA: 140] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 03/07/2016] [Indexed: 12/13/2022] Open
Abstract
UNLABELLED Spinal cord injuries (SCIs) result in devastating lifelong disability for patients and their families. The initial mechanical trauma is followed by a damaging secondary injury cascade involving proapoptotic signaling, ischemia, and inflammatory cell infiltration. Ongoing cellular necrosis releases ATP, DNA, glutamate, and free radicals to create a cytotoxic postinjury milieu. Long-term regeneration of lost or injured networks is further impeded by cystic cavitation and the formation of an inhibitory glial-chondroitin sulfate proteoglycan scar. In this article, we discuss important neuroprotective interventions currently applied in clinical practice, including surgical decompression, blood pressure augmentation, and i.v. methylprednisolone. We then explore exciting translational therapies on the horizon, such as riluzole, minocycline, fibroblast growth factor, magnesium, and hypothermia. Finally, we summarize the key neuroregenerative strategies of the next decade, including glial scar degradation, Rho-ROCK inhibition, cell-based therapies, and novel bioengineered adjuncts. Throughout, we emphasize the need for combinatorial approaches to this multifactorial problem and discuss relevant studies at the forefront of translation. We conclude by providing our perspectives on the future direction of SCI research. SIGNIFICANCE Spinal cord injuries (SCIs) result in devastating, lifelong disability for patients and their families. This article discusses important neuroprotective interventions currently applied in clinical practice, including surgical decompression, blood pressure augmentation, and i.v. methylprednisolone. Translational therapies on the horizon are discussed, such as riluzole, minocycline, fibroblast growth factor, magnesium, and hypothermia. The key neuroregenerative strategies of the next decade are summarized, including glial scar degradation, Rho-ROCK inhibition, cell-based therapies, and novel bioengineered adjuncts. The need for combinatorial approaches to this multifactorial problem is emphasized, relevant studies at the forefront of translation are discussed, and perspectives on the future direction of SCI research are presented.
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Affiliation(s)
- Christopher S Ahuja
- Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Ontario, Canada Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Michael Fehlings
- Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Ontario, Canada Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada McEwen Centre for Regenerative Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada Department of Surgery, University of Toronto, Toronto, Ontario, Canada Spine Program, University of Toronto, Toronto, Ontario, Canada McLaughlin Centre for Molecular Medicine, University of Toronto, Toronto, Ontario, Canada
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Dyck SM, Karimi-Abdolrezaee S. Chondroitin sulfate proteoglycans: Key modulators in the developing and pathologic central nervous system. Exp Neurol 2015; 269:169-87. [PMID: 25900055 DOI: 10.1016/j.expneurol.2015.04.006] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 04/11/2015] [Accepted: 04/14/2015] [Indexed: 12/15/2022]
Abstract
Chondroitin Sulfate Proteoglycans (CSPGs) are a major component of the extracellular matrix in the central nervous system (CNS) and play critical role in the development and pathophysiology of the brain and spinal cord. Developmentally, CSPGs provide guidance cues for growth cones and contribute to the formation of neuronal boundaries in the developing CNS. Their presence in perineuronal nets plays a crucial role in the maturation of synapses and closure of critical periods by limiting synaptic plasticity. Following injury to the CNS, CSPGs are dramatically upregulated by reactive glia which form a glial scar around the lesion site. Increased level of CSPGs is a hallmark of all CNS injuries and has been shown to limit axonal plasticity, regeneration, remyelination, and conduction after injury. Additionally, CSPGs create a non-permissive milieu for cell replacement activities by limiting cell migration, survival and differentiation. Mounting evidence is currently shedding light on the potential benefits of manipulating CSPGs in combination with other therapeutic strategies to promote spinal cord repair and regeneration. Moreover, the recent discovery of multiple receptors for CSPGs provides new therapeutic targets for targeted interventions in blocking the inhibitory properties of CSPGs following injury. Here, we will provide an in depth discussion on the impact of CSPGs in normal and pathological CNS. We will also review the recent preclinical therapies that have been developed to target CSPGs in the injured CNS.
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Affiliation(s)
- Scott M Dyck
- Regenerative Medicine Program, Department of Physiology and the Spinal Cord Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Soheila Karimi-Abdolrezaee
- Regenerative Medicine Program, Department of Physiology and the Spinal Cord Research Centre, University of Manitoba, Winnipeg, Manitoba, Canada.
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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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Abstract
Three theories of regeneration dominate neuroscience today, all purporting to explain why the adult central nervous system (CNS) cannot regenerate. One theory proposes that Nogo, a molecule expressed by myelin, prevents axonal growth. The second theory emphasizes the role of glial scars. The third theory proposes that chondroitin sulfate proteoglycans (CSPGs) prevent axon growth. Blockade of Nogo, CSPG, and their receptors indeed can stop axon growth in vitro and improve functional recovery in animal spinal cord injury (SCI) models. These therapies also increase sprouting of surviving axons and plasticity. However, many investigators have reported regenerating spinal tracts without eliminating Nogo, glial scar, or CSPG. For example, many motor and sensory axons grow spontaneously in contused spinal cords, crossing gliotic tissue and white matter surrounding the injury site. Sensory axons grow long distances in injured dorsal columns after peripheral nerve lesions. Cell transplants and treatments that increase cAMP and neurotrophins stimulate motor and sensory axons to cross glial scars and to grow long distances in white matter. Genetic studies deleting all members of the Nogo family and even the Nogo receptor do not always improve regeneration in mice. A recent study reported that suppressing the phosphatase and tensin homolog (PTEN) gene promotes prolific corticospinal tract regeneration. These findings cannot be explained by the current theories proposing that Nogo and glial scars prevent regeneration. Spinal axons clearly can and will grow through glial scars and Nogo-expressing tissue under some circumstances. The observation that deleting PTEN allows corticospinal tract regeneration indicates that the PTEN/AKT/mTOR pathway regulates axonal growth. Finally, many other factors stimulate spinal axonal growth, including conditioning lesions, cAMP, glycogen synthetase kinase inhibition, and neurotrophins. To explain these disparate regenerative phenomena, I propose that the spinal cord has evolved regenerative mechanisms that are normally suppressed by multiple extrinsic and intrinsic factors but can be activated by injury, mediated by the PTEN/AKT/mTOR, cAMP, and GSK3b pathways, to stimulate neural growth and proliferation.
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Affiliation(s)
- Wise Young
- W. M. Keck Center for Collaborative Neuroscience, Rutgers, State University of New Jersey, Piscataway, NJ, USA
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Examination of the combined effects of chondroitinase ABC, growth factors and locomotor training following compressive spinal cord injury on neuroanatomical plasticity and kinematics. PLoS One 2014; 9:e111072. [PMID: 25350665 PMCID: PMC4211738 DOI: 10.1371/journal.pone.0111072] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 09/23/2014] [Indexed: 12/13/2022] Open
Abstract
While several cellular and pharmacological treatments have been evaluated following spinal cord injury (SCI) in animal models, it is increasingly recognized that approaches to address the glial scar, including the use of chondroitinase ABC (ChABC), can facilitate neuroanatomical plasticity. Moreover, increasing evidence suggests that combinatorial strategies are key to unlocking the plasticity that is enabled by ChABC. Given this, we evaluated the anatomical and functional consequences of ChABC in a combinatorial approach that also included growth factor (EGF, FGF2 and PDGF-AA) treatments and daily treadmill training on the recovery of hindlimb locomotion in rats with mid thoracic clip compression SCI. Using quantitative neuroanatomical and kinematic assessments, we demonstrate that the combined therapy significantly enhanced the neuroanatomical plasticity of major descending spinal tracts such as corticospinal and serotonergic-spinal pathways. Additionally, the pharmacological treatment attenuated chronic astrogliosis and inflammation at and adjacent to the lesion with the modest synergistic effects of treadmill training. We also observed a trend for earlier recovery of locomotion accompanied by an improvement of the overall angular excursions in rats treated with ChABC and growth factors in the first 4 weeks after SCI. At the end of the 7-week recovery period, rats from all groups exhibited an impressive spontaneous recovery of the kinematic parameters during locomotion on treadmill. However, although the combinatorial treatment led to clear chronic neuroanatomical plasticity, these structural changes did not translate to an additional long-term improvement of locomotor parameters studied including hindlimb-forelimb coupling. These findings demonstrate the beneficial effects of combined ChABC, growth factors and locomotor training on the plasticity of the injured spinal cord and the potential to induce earlier neurobehavioral recovery. However, additional approaches such as stem cell therapies or a more adapted treadmill training protocol may be required to optimize this repair strategy in order to induce sustained functional locomotor improvement.
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Cannabinoid CB2 receptor (CB2R) stimulation delays rubrospinal mitochondrial-dependent degeneration and improves functional recovery after spinal cord hemisection by ERK1/2 inactivation. Cell Death Dis 2014; 5:e1404. [PMID: 25188514 PMCID: PMC4540196 DOI: 10.1038/cddis.2014.364] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 07/11/2014] [Accepted: 07/22/2014] [Indexed: 12/19/2022]
Abstract
Spinal cord injury (SCI) is a devastating condition of CNS that often results in severe functional impairments for which there are no restorative therapies. As in other CNS injuries, in addition to the effects that are related to the primary site of damage, these impairments are caused by degeneration of distal regions that are connected functionally to the primary lesion site. Modulation of the endocannabinoid system (ECS) counteracts this neurodegeneration, and pharmacological modulation of type-2 cannabinoid receptor (CB2R) is a promising therapeutic target for several CNS pathologies, including SCI. This study examined the effects of CB2R modulation on the fate of axotomized rubrospinal neurons (RSNs) and functional recovery in a model of spinal cord dorsal hemisection (SCH) at the cervical level in rats. SCH induced CB2R expression, severe atrophy, and cell death in contralateral RSNs. Furthermore, SCH affected molecular changes in the apoptotic cascade in RSNs – increased cytochrome c release, apoptosome formation, and caspase-3 activity. CB2R stimulation by its selective agonist JWH-015 significantly increased the bcl-2/bax ratio, reduced cytochrome c release, delayed atrophy and degeneration, and improved spontaneous functional recovery through ERK1/2 inactivation. These findings implicate the ECS, particularly CB2R, as part of the endogenous neuroprotective response that is triggered after SCI. Thus, CB2R modulation might represent a promising therapeutic target that lacks psychotropic effects and can be used to exploit ECS-based approaches to counteract neuronal degeneration.
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Large-scale chondroitin sulfate proteoglycan digestion with chondroitinase gene therapy leads to reduced pathology and modulates macrophage phenotype following spinal cord contusion injury. J Neurosci 2014; 34:4822-36. [PMID: 24695702 DOI: 10.1523/jneurosci.4369-13.2014] [Citation(s) in RCA: 164] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Chondroitin sulfate proteoglycans (CSPGs) inhibit repair following spinal cord injury. Here we use mammalian-compatible engineered chondroitinase ABC (ChABC) delivered via lentiviral vector (LV-ChABC) to explore the consequences of large-scale CSPG digestion for spinal cord repair. We demonstrate significantly reduced secondary injury pathology in adult rats following spinal contusion injury and LV-ChABC treatment, with reduced cavitation and enhanced preservation of spinal neurons and axons at 12 weeks postinjury, compared with control (LV-GFP)-treated animals. To understand these neuroprotective effects, we investigated early inflammatory changes following LV-ChABC treatment. Increased expression of the phagocytic macrophage marker CD68 at 3 d postinjury was followed by increased CD206 expression at 2 weeks, indicating that large-scale CSPG digestion can alter macrophage phenotype to favor alternatively activated M2 macrophages. Accordingly, ChABC treatment in vitro induced a significant increase in CD206 expression in unpolarized monocytes stimulated with conditioned medium from spinal-injured tissue explants. LV-ChABC also promoted the remodelling of specific CSPGs as well as enhanced vascularity, which was closely associated with CD206-positive macrophages. Neuroprotective effects of LV-ChABC corresponded with improved sensorimotor function, evident as early as 1 week postinjury, a time point when increased neuronal survival correlated with reduced apoptosis. Improved function was maintained into chronic injury stages, where improved axonal conduction and increased serotonergic innervation were also observed. Thus, we demonstrate that ChABC gene therapy can modulate secondary injury processes, with neuroprotective effects that lead to long-term improved functional outcome and reveal novel mechanistic evidence that modulation of macrophage phenotype may underlie these effects.
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Kanno H, Pressman Y, Moody A, Berg R, Muir EM, Rogers JH, Ozawa H, Itoi E, Pearse DD, Bunge MB. Combination of engineered Schwann cell grafts to secrete neurotrophin and chondroitinase promotes axonal regeneration and locomotion after spinal cord injury. J Neurosci 2014; 34:1838-55. [PMID: 24478364 PMCID: PMC3905147 DOI: 10.1523/jneurosci.2661-13.2014] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 11/14/2013] [Accepted: 12/19/2013] [Indexed: 11/21/2022] Open
Abstract
Transplantation of Schwann cells (SCs) is a promising therapeutic strategy for spinal cord repair. SCs introduced into lesions support axon regeneration, but because these axons do not exit the transplant, additional approaches with SCs are needed. Here, we transplanted SCs genetically modified to secrete a bifunctional neurotrophin (D15A) and chondroitinase ABC (ChABC) into a subacute contusion injury in rats. We examined the effects of these modifications on graft volume, SC number, degradation of chondroitin sulfate proteoglycans (CSPGs), astrogliosis, SC myelination of axons, propriospinal and supraspinal axon numbers, locomotor outcome (BBB scoring, CatWalk gait analysis), and mechanical and thermal sensitivity on the hind paws. D15A secreted from transplanted SCs increased graft volume and SC number and myelinated axon number. SCs secreting ChABC significantly decreased CSPGs, led to some egress of SCs from the graft, and increased propriospinal and 5-HT-positive axons in the graft. SCs secreting both D15A and ChABC yielded the best responses: (1) the largest number of SC myelinated axons, (2) more propriospinal axons in the graft and host tissue around and caudal to it, (3) more corticospinal axons closer to the graft and around and caudal to it, (4) more brainstem neurons projecting caudal to the transplant, (5) increased 5-HT-positive axons in the graft and caudal to it, (6) significant improvement in aspects of locomotion, and (7) improvement in mechanical and thermal allodynia. This is the first evidence that the combination of SC transplants engineered to secrete neurotrophin and chondroitinase further improves axonal regeneration and locomotor and sensory function.
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Affiliation(s)
- Haruo Kanno
- Miami Project to Cure Paralysis
- Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan, 9808574
| | | | | | | | - Elizabeth M. Muir
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, CB2 3EG, United Kingdom, and
| | - John H. Rogers
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, CB2 3EG, United Kingdom, and
| | - Hiroshi Ozawa
- Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan, 9808574
| | - Eiji Itoi
- Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan, 9808574
| | - Damien D. Pearse
- Miami Project to Cure Paralysis
- Department of Neurological Surgery
- Neuroscience Program
- Interdisciplinary Stem Cell Institute, and
| | - Mary Bartlett Bunge
- Miami Project to Cure Paralysis
- Department of Neurological Surgery
- Neuroscience Program
- Interdisciplinary Stem Cell Institute, and
- Department of Cell Biology, University of Miami Miller School of Medicine, Miami, Florida 33136
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Burnside ER, Bradbury EJ. Review: Manipulating the extracellular matrix and its role in brain and spinal cord plasticity and repair. Neuropathol Appl Neurobiol 2014; 40:26-59. [DOI: 10.1111/nan.12114] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 12/20/2013] [Indexed: 12/17/2022]
Affiliation(s)
- E. R. Burnside
- King's College London; Regeneration Group; The Wolfson Centre for Age-Related Diseases; Guy's Campus; London UK
| | - E. J. Bradbury
- King's College London; Regeneration Group; The Wolfson Centre for Age-Related Diseases; Guy's Campus; London UK
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Schwartz NB, Domowicz MS. Chemistry and Function of Glycosaminoglycans in the Nervous System. ADVANCES IN NEUROBIOLOGY 2014; 9:89-115. [DOI: 10.1007/978-1-4939-1154-7_5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Combination of Chondroitinase ABC, Glial Cell Line–Derived Neurotrophic Factor and Nogo A Antibody Delayed-Release Microspheres Promotes the Functional Recovery of Spinal Cord Injury. J Craniofac Surg 2013; 24:2153-7. [DOI: 10.1097/01.scs.0000436700.65891.3b] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Renno WM, Al-Khaledi G, Mousa A, Karam SM, Abul H, Asfar S. (-)-Epigallocatechin-3-gallate (EGCG) modulates neurological function when intravenously infused in acute and, chronically injured spinal cord of adult rats. Neuropharmacology 2013; 77:100-19. [PMID: 24071567 DOI: 10.1016/j.neuropharm.2013.09.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 08/13/2013] [Accepted: 09/09/2013] [Indexed: 12/17/2022]
Abstract
Spinal cord injury (SCI) causes severe and long lasting motor and sensory deficits, chronic pain, and autonomic dysreflexia. (-)-epigallocatechin-3-gallate (EGCG) has shown to produce neuroprotective effect in a broad range of neurodegenerative disease animal models. This study designed to test the efficacy of intravenous infusion of EGCG for 36 h, in acutely injured rats' spinal cord: within first 4 h post-injury and, in chronically SC injured rats: after one year of injury. Functional outcomes measured using standard BBB scale, The Louisville Swim Scale (LSS) and, pain behavior assessment tests. 72 Female adult rats subjected to moderate thoracic SCI using MASCIS Impactor, blindly randomized as the following: (I) Acute SCI + EGCG (II) Acute SCI + saline. (III) Chronic SCI + EGCG. (IV) Chronic SCI + saline and, sham SCI animals. EGCG i.v. treatment of acute and, chronic SCI animals resulted in significantly better recovery of motor and sensory functions, BBB and LSS (P < 0.005) and (P < 0.05) respectively. Tactile allodynia, mechanical nociception (P < 0.05) significantly improved. Paw withdrawal and, tail flick latencies increase significantly (P < 0.05). Moreover, in the EGCG treated acute SCI animals the percentage of lesion size area significantly reduced (P < 0.0001) and, the number of neurons in the spinal cord increased (P < 0.001). Percent areas of GAP-43 and GFAP immunohistochemistry showed significant (P < 0.05) increase. We conclude that the therapeutic window of opportunity for EGCG to depict neurological recovery in SCI animals, is viable up to one year post SCI when intravenously infused for 36 h.
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Affiliation(s)
- Waleed M Renno
- Department of Anatomy, Kuwait University, Faculty of Medicine, Kuwait.
| | - Ghanim Al-Khaledi
- Department of Pharmacology, Kuwait University, Faculty of Medicine, Kuwait
| | - Alyaa Mousa
- Department of Anatomy, Kuwait University, Faculty of Medicine, Kuwait
| | - Shaima M Karam
- Department of Pharmacology, Kuwait University, Faculty of Medicine, Kuwait
| | - Habib Abul
- Department of Pharmacology, Kuwait University, Faculty of Medicine, Kuwait
| | - Sami Asfar
- Department of Surgery, Kuwait University, Faculty of Medicine, Kuwait
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29
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Gherardini L, Gennaro M, Pizzorusso T. Perilesional treatment with chondroitinase ABC and motor training promote functional recovery after stroke in rats. Cereb Cortex 2013; 25:202-12. [PMID: 23960208 DOI: 10.1093/cercor/bht217] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Ischemic stroke insults may lead to chronic functional limitations that adversely affect patient movements. Partial motor recovery is thought to be sustained by neuronal plasticity, particularly in areas close to the lesion site. It is still unknown if treatments acting exclusively on cortical plasticity of perilesional areas could result in behavioral amelioration. We tested whether enhancing plasticity in the ipsilesional cortex using local injections of chondroitinase ABC (ChABC) could promote recovery of skilled motor function in a focal cortical ischemia of forelimb motor cortex in rats. Using the skilled reaching test, we found that acute and delayed ChABC treatment induced recovery of impaired motor skills in treated rats. vGLUT1, vGLUT2, and vGAT staining indicated that functional recovery after acute ChABC treatment was associated with local plastic modification of the excitatory cortical circuitry positive for VGLUT2. ChABC effects on vGLUT2 staining were present only in rats undergoing behavioral training. Thus, the combination of treatments targeting the CSPG component of the extracellular matrix in perilesional areas and rehabilitation could be sufficient to enhance functional recovery from a focal stroke.
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Affiliation(s)
- Lisa Gherardini
- Institute of Neuroscience, CNR, Pisa 56124, Italy, Institute of Clinical Physiology, CNR, Siena 53100, Italy and
| | | | - Tommaso Pizzorusso
- Institute of Neuroscience, CNR, Pisa 56124, Italy, NEUROFARBA Dept, University of Florence, Florence 50135, Italy
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30
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Forgione N, Fehlings MG. Rho-ROCK inhibition in the treatment of spinal cord injury. World Neurosurg 2013; 82:e535-9. [PMID: 23298675 DOI: 10.1016/j.wneu.2013.01.009] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 01/03/2013] [Indexed: 11/18/2022]
Abstract
BACKGROUND The Rho pathway has been shown to have a role in the pathophysiology of spinal cord injury (SCI). Upregulation of the Rho signaling pathway occurs as a result of SCI. Activation of Rho and its downstream effector kinases triggers growth cone collapse and represents a significant barrier to axon regeneration. Furthermore, there is evidence that Rho-ROCK signaling mediates the inhibitory effects of chondroitin sulfate proteoglycans on neurons, and that inhibition of Rho and ROCK can reverse chondroitin sulfate proteoglycan-mediated inhibition of neurite outgrowth. Work building on these findings suggests that inhibition of this pathway may boost neuroprotection and axonal regeneration after SCI. METHODS A narrative review. RESULTS Investigators have identified a C3 transferase, which selectively inhibits Rho without affecting other guanine triphosphatases. This has been shown to promote axonal sprouting and recovery of locomotor function after hemisection of the thoracic spinal cord in a mouse model of SCI. The neuroprotective properties of Rho inhibitors in animal models of SCI have been reinforced by studies carried out in vitro using retinal ganglion cells. In light of this, a Rho inhibitor known as Cethrin has been evaluated as a therapeutic intervention for SCI in a phase I/IIa clinical trial with promising results. CONCLUSIONS The Rho pathway has been shown to have a role in the pathophysiology of SCI and preclinical and clinical work and is currently a promising target for the treatment of patients with SCI.
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Affiliation(s)
- Nicole Forgione
- Division of Genetics and Development, Toronto Western Research Institute, Toronto, Ontario, Canada
| | - Michael G Fehlings
- Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada.
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31
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Nicaise C, Putatunda R, Hala TJ, Regan KA, Frank DM, Brion JP, Leroy K, Pochet R, Wright MC, Lepore AC. Degeneration of phrenic motor neurons induces long-term diaphragm deficits following mid-cervical spinal contusion in mice. J Neurotrauma 2012; 29:2748-60. [PMID: 23176637 DOI: 10.1089/neu.2012.2467] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
A primary cause of morbidity and mortality following cervical spinal cord injury (SCI) is respiratory compromise, regardless of the level of trauma. In particular, SCI at mid-cervical regions targets degeneration of both descending bulbospinal respiratory axons and cell bodies of phrenic motor neurons, resulting in deficits in the function of the diaphragm, the primary muscle of inspiration. Contusion-type trauma to the cervical spinal cord is one of the most common forms of human SCI; however, few studies have evaluated mid-cervical contusion in animal models or characterized consequent histopathological and functional effects of degeneration of phrenic motor neuron-diaphragm circuitry. We have generated a mouse model of cervical contusion SCI that unilaterally targets both C4 and C5 levels, the location of the phrenic motor neuron pool, and have examined histological and functional outcomes for up to 6 weeks post-injury. We report that phrenic motor neuron loss in cervical spinal cord, phrenic nerve axonal degeneration, and denervation at diaphragm neuromuscular junctions (NMJ) resulted in compromised ipsilateral diaphragm function, as demonstrated by persistent reduction in diaphragm compound muscle action potential amplitudes following phrenic nerve stimulation and abnormalities in spontaneous diaphragm electromyography (EMG) recordings. This injury paradigm is reproducible, does not require ventilatory assistance, and provides proof-of-principle that generation of unilateral cervical contusion is a feasible strategy for modeling diaphragmatic/respiratory deficits in mice. This study and its accompanying analyses pave the way for using transgenic mouse technology to explore the function of specific genes in the pathophysiology of phrenic motor neuron degeneration and respiratory dysfunction following cervical SCI.
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Affiliation(s)
- Charles Nicaise
- Department of Neuroscience, Farber Institute for Neurosciences, Thomas Jefferson University Medical College, Philadelphia, Pennsylvania, USA
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Starkey ML, Bartus K, Barritt AW, Bradbury EJ. Chondroitinase ABC promotes compensatory sprouting of the intact corticospinal tract and recovery of forelimb function following unilateral pyramidotomy in adult mice. Eur J Neurosci 2012; 36:3665-78. [PMID: 23061434 DOI: 10.1111/ejn.12017] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 08/26/2012] [Accepted: 09/12/2012] [Indexed: 12/11/2022]
Abstract
Chondroitin sulphate proteoglycans (CSPGs) are extracellular matrix molecules whose inhibitory activity is attenuated by the enzyme chondroitinase ABC (ChABC). Here we assess whether CSPG degradation can promote compensatory sprouting of the intact corticospinal tract (CST) following unilateral injury and restore function to the denervated forelimb. Adult C57BL/6 mice underwent unilateral pyramidotomy and treatment with either ChABC or a vehicle control. Significant impairments in forepaw symmetry were observed following pyramidotomy, with injured mice preferentially using their intact paw during spontaneous vertical exploration of a cylinder. No recovery on this task was observed in vehicle-treated mice. However, ChABC-treated mice showed a marked recovery of function, with forelimb symmetry fully restored by 5 weeks post-injury. Functional recovery was associated with robust sprouting of the uninjured CST, with numerous axons observed crossing the midline in the brainstem and spinal cord and terminating in denervated grey matter. CST fibres in the denervated side of the spinal cord following ChABC treatment were closely associated with the synaptic marker vGlut1. Immunohistochemical assessment of chondroitin-4-sulphate revealed that CSPGs were heavily digested around lamina X, alongside midline crossing axons and in grey matter regions where sprouting axons and reduced peri-neuronal net staining was observed. Thus, we demonstrate that CSPG degradation promotes midline crossing and reinnervation of denervated target regions by intact CST axons and leads to restored function in the denervated forepaw. Enhancing compensatory sprouting using ChABC provides a route to restore function that could be applied to disorders such as spinal cord injury and stroke.
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Affiliation(s)
- Michelle L Starkey
- Regeneration Group, King's College London, Wolfson Centre for Age-Related Diseases, Hodgkin Building, Guy's Campus, London Bridge, London, SE1 IUL, UK
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Wilcox JT, Cadotte D, Fehlings MG. Spinal cord clinical trials and the role for bioengineering. Neurosci Lett 2012; 519:93-102. [PMID: 22366402 DOI: 10.1016/j.neulet.2012.02.028] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 02/08/2012] [Indexed: 12/31/2022]
Abstract
There is considerable need for bringing effective therapies for spinal cord injury (SCI) to the clinic. Excellent medical and surgical management has mitigated poor prognoses after SCI; however, few advances have been made to return lost function. Bioengineering approaches have shown great promise in preclinical rodent models, yet there remains a large translational gap to carry these forward in human trials. Herein, we provide a framework of human clinical trials, an overview of past trials for SCI, as well as bioengineered approaches that include: directly applied pharmacologics, cellular transplantation, biomaterials and functional neurorehabilitation. Success of novel therapies will require the correct application of comprehensive preclinical studies with well-designed and expertly conducted human clinical trials. While biologics and bioengineered strategies are widely considered to represent the high potential benefits for those who have sustained a spinal injury, few such therapies have been thoroughly tested with appreciable efficacy for use in human SCI. With these considerations, we propose that bioengineered strategies are poised to enter clinical trials.
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Affiliation(s)
- Jared T Wilcox
- Institute of Medical Science, University of Toronto, Toronto, Canada M5S 1A8
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Reier PJ, Lane MA, Hall ED, Teng YD, Howland DR. Translational spinal cord injury research: preclinical guidelines and challenges. HANDBOOK OF CLINICAL NEUROLOGY 2012; 109:411-33. [PMID: 23098728 PMCID: PMC4288927 DOI: 10.1016/b978-0-444-52137-8.00026-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Advances in the neurobiology of spinal cord injury (SCI) have prompted increasing attention to opportunities for moving experimental strategies towards clinical applications. Preclinical studies are the centerpiece of the translational process. A major challenge is to establish strategies for achieving optimal translational progression while minimizing potential repetition of previous disappointments associated with clinical trials. This chapter reviews and expands upon views pertaining to preclinical design reported in recently published opinion surveys. Subsequent discussion addresses other preclinical considerations more specifically related to current and potentially imminent cellular and pharmacological approaches to acute/subacute and chronic SCI. Lastly, a retrospective and prospective analysis examines how guidelines currently under discussion relate to select examples of past, current, and future clinical translations. Although achieving definition of the "perfect" preclinical scenario is difficult to envision, this review identifies therapeutic robustness and independent replication of promising experimental findings as absolutely critical prerequisites for clinical translation. Unfortunately, neither has been fully embraced thus far. Accordingly, this review challenges the notion "everything works in animals and nothing in humans", since more rigor must first be incorporated into the bench-to-bedside translational process by all concerned, whether in academia, clinical medicine, or corporate circles.
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Affiliation(s)
- Paul J Reier
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, USA.
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35
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Kwok JC, Dick G, Wang D, Fawcett JW. Extracellular matrix and perineuronal nets in CNS repair. Dev Neurobiol 2011; 71:1073-89. [DOI: 10.1002/dneu.20974] [Citation(s) in RCA: 303] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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36
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Bartus K, James ND, Bosch KD, Bradbury EJ. Chondroitin sulphate proteoglycans: key modulators of spinal cord and brain plasticity. Exp Neurol 2011; 235:5-17. [PMID: 21871887 DOI: 10.1016/j.expneurol.2011.08.008] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Revised: 07/15/2011] [Accepted: 08/08/2011] [Indexed: 01/08/2023]
Abstract
Chondroitin sulphate proteoglycans (CSPGs) are a family of inhibitory extracellular matrix molecules that are highly expressed during development, where they are involved in processes of pathfinding and guidance. CSPGs are present at lower levels in the mature CNS, but are highly concentrated in perineuronal nets where they play an important role in maintaining stability and restricting plasticity. Whilst important for maintaining stable connections, this can have an adverse effect following insult to the CNS, restricting the capacity for repair, where enhanced synapse formation leading to new connections could be functionally beneficial. CSPGs are also highly expressed at CNS injury sites, where they can restrict anatomical plasticity by inhibiting sprouting and reorganisation, curbing the extent to which spared systems may compensate for the loss function of injured pathways. Modification of CSPGs, usually involving enzymatic degradation of glycosaminoglycan chains from the CSPG molecule, has received much attention as a potential strategy for promoting repair following spinal cord and brain injury. Pre-clinical studies in animal models have demonstrated a number of reparative effects of CSPG modification, which are often associated with functional recovery. Here we discuss the potential of CSPG modification to stimulate restorative plasticity after injury, reviewing evidence from studies in the brain, the spinal cord and the periphery.
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Affiliation(s)
- K Bartus
- Wolfson Centre for Age-Related Diseases, King's College London, Guy's Campus, London Bridge, SE1 1UL, UK.
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37
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Zhang SX, Huang F, Gates M, Holmberg EG. Scar ablation combined with LP/OEC transplantation promotes anatomical recovery and P0-positive myelination in chronically contused spinal cord of rats. Brain Res 2011; 1399:1-14. [DOI: 10.1016/j.brainres.2011.05.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 04/30/2011] [Accepted: 05/02/2011] [Indexed: 01/27/2023]
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Jefferson SC, Tester NJ, Howland DR. Chondroitinase ABC promotes recovery of adaptive limb movements and enhances axonal growth caudal to a spinal hemisection. J Neurosci 2011; 31:5710-20. [PMID: 21490212 PMCID: PMC3117673 DOI: 10.1523/jneurosci.4459-10.2011] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 01/17/2011] [Accepted: 02/16/2011] [Indexed: 01/23/2023] Open
Abstract
A number of studies have shown that chondroitinase ABC (Ch'ase ABC) digestion of inhibitory chondroitin sulfate glycosaminoglycans significantly enhances axonal growth and recovery in rodents following spinal cord injury (SCI). Further, our group has shown improved recovery following SCI in the larger cat model. The purpose of the current study was to determine whether intraspinal delivery of Ch'ase ABC, following T10 hemisections in adult cats, enhances adaptive movement features during a skilled locomotor task and/or promotes plasticity of spinal and supraspinal circuitry. Here, we show that Ch'ase ABC enhanced crossing of a peg walkway post-SCI and significantly improved ipsilateral hindlimb trajectories and integration into a functional forelimb-hindlimb coordination pattern. Recovery of these complex movements was associated with significant increases in neurofilament immunoreactivity immediately below the SCI in the ipsilateral white (p = 0.033) and contralateral gray matter (p = 0.003). Further, the rubrospinal tract is critical in the normal cat during skilled movements that require accurate paw placements and trajectories like those seen during peg walkway crossing. Rubrospinal connections were assessed following Fluoro-Gold injections, caudal to the hemisection. Significantly more retrogradely labeled right (axotomized) red nucleus (RN) neurons were seen in Ch'ase ABC-treated (23%) compared with control-treated cats (8%; p = 0.032) indicating that a larger number of RN neurons in Ch'ase ABC-treated cats had axons below the lesion level. Thus, following SCI, Ch'ase ABC may facilitate axonal growth at the spinal level, enhance adaptive features of locomotion, and affect plasticity of rubrospinal circuitry known to support adaptive behaviors in the normal cat.
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Affiliation(s)
- Stephanie C Jefferson
- Brain Rehabilitation and Research Center, Malcom Randall VA Medical Center, Gainesville, North Florida/South Georgia Veterans Health System, Florida 32608, USA
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