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Jiang Y, Cai Y, Yang N, Gao S, Li Q, Pang Y, Su P. Molecular mechanisms of spinal cord injury repair across vertebrates: A comparative review. Eur J Neurosci 2024; 60:4552-4568. [PMID: 38978308 DOI: 10.1111/ejn.16462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 05/09/2024] [Accepted: 06/20/2024] [Indexed: 07/10/2024]
Abstract
In humans and other adult mammals, axon regeneration is difficult in axotomized neurons. Therefore, spinal cord injury (SCI) is a devastating event that can lead to permanent loss of locomotor and sensory functions. Moreover, the molecular mechanisms of axon regeneration in vertebrates are not very well understood, and currently, no effective treatment is available for SCI. In striking contrast to adult mammals, many nonmammalian vertebrates such as reptiles, amphibians, bony fishes and lampreys can spontaneously resume locomotion even after complete SCI. In recent years, rapid progress in the development of next-generation sequencing technologies has offered valuable information on SCI. In this review, we aimed to provide a comparison of axon regeneration process across classical model organisms, focusing on crucial genes and signalling pathways that play significant roles in the regeneration of individually identifiable descending neurons after SCI. Considering the special evolutionary location and powerful regenerative ability of lamprey and zebrafish, they will be the key model organisms for ongoing studies on spinal cord regeneration. Detailed study of SCI in these model organisms will help in the elucidation of molecular mechanisms of neuron regeneration across species.
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Affiliation(s)
- Ying Jiang
- College of Life Science, Liaoning Normal University, Dalian, China
- Lamprey Research Center, Liaoning Normal University, Dalian, China
- Collaborative Innovation Center of Seafood Deep Processing, Dalian Polytechnic University, Dalian, China
| | - Yang Cai
- College of Life Science, Liaoning Normal University, Dalian, China
- Lamprey Research Center, Liaoning Normal University, Dalian, China
- Collaborative Innovation Center of Seafood Deep Processing, Dalian Polytechnic University, Dalian, China
| | - Ning Yang
- College of Life Science, Liaoning Normal University, Dalian, China
- Lamprey Research Center, Liaoning Normal University, Dalian, China
- Collaborative Innovation Center of Seafood Deep Processing, Dalian Polytechnic University, Dalian, China
| | - Si Gao
- College of Life Science, Liaoning Normal University, Dalian, China
- Lamprey Research Center, Liaoning Normal University, Dalian, China
- Collaborative Innovation Center of Seafood Deep Processing, Dalian Polytechnic University, Dalian, China
| | - Qingwei Li
- College of Life Science, Liaoning Normal University, Dalian, China
- Lamprey Research Center, Liaoning Normal University, Dalian, China
- Collaborative Innovation Center of Seafood Deep Processing, Dalian Polytechnic University, Dalian, China
| | - Yue Pang
- College of Life Science, Liaoning Normal University, Dalian, China
- Lamprey Research Center, Liaoning Normal University, Dalian, China
- Collaborative Innovation Center of Seafood Deep Processing, Dalian Polytechnic University, Dalian, China
| | - Peng Su
- College of Life Science, Liaoning Normal University, Dalian, China
- Lamprey Research Center, Liaoning Normal University, Dalian, China
- Collaborative Innovation Center of Seafood Deep Processing, Dalian Polytechnic University, Dalian, China
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Hough RA, McClellan AD. Spinal cord injury significantly alters the properties of reticulospinal neurons: delayed repolarization mediated by potassium channels. J Neurophysiol 2023; 130:1265-1281. [PMID: 37820016 PMCID: PMC10994645 DOI: 10.1152/jn.00251.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 09/21/2023] [Accepted: 10/10/2023] [Indexed: 10/13/2023] Open
Abstract
After rostral spinal cord injury (SCI) of lampreys, the descending axons of injured (axotomized) reticulospinal (RS) neurons regenerate and locomotor function gradually recovers. Our previous studies indicated that relative to uninjured lamprey RS neurons, injured RS neurons display several dramatic changes in their biophysical properties, called the "injury phenotype." In the present study, at the onset of applied depolarizing current pulses for membrane potentials below as well as above threshold for action potentials (APs), injured RS neurons displayed a transient depolarization consisting of an initial depolarizing component followed by a delayed repolarizing component. In contrast, for uninjured neurons the transient depolarization was mostly only evident at suprathreshold voltages when APs were blocked. For injured RS neurons, the delayed repolarizing component resisted depolarization to threshold and made these neurons less excitable than uninjured RS neurons. After block of voltage-gated sodium and calcium channels for injured RS neurons, the transient depolarization was still present. After a further block of voltage-gated potassium channels, the delayed repolarizing component was abolished or significantly reduced, with little or no effect on the initial depolarizing component. Voltage-clamp experiments indicated that the delayed repolarizing component was due to a noninactivating outward-rectifying potassium channel whose conductance (gK) was significantly larger for injured RS neurons compared to that for uninjured neurons. Thus, SCI results in an increase in gK and other changes in the biophysical properties of injured lamprey RS neurons that lead to a reduction in excitability, which is proposed to create an intracellular environment that supports axonal regeneration.NEW & NOTEWORTHY After spinal cord injury (SCI), lamprey reticulospinal (RS) neurons responded to subthreshold depolarizing current pulses with a transient depolarization, which included an initial depolarization that was due to passive channels followed by a delayed repolarization that was mediated by voltage-gated potassium channels. The conductance of these channels (gK) was significantly increased for RS neurons after SCI and contributed to a reduction in excitability, which is expected to provide supportive conditions for subsequent axonal regeneration.
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Affiliation(s)
- Ryan A Hough
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, United States
| | - Andrew D McClellan
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, United States
- Interdisciplinary Neuroscience Program, University of Missouri, Columbia, Missouri, United States
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Maxson Jones K, Morgan JR. Lampreys and spinal cord regeneration: "a very special claim on the interest of zoologists," 1830s-present. Front Cell Dev Biol 2023; 11:1113961. [PMID: 37228651 PMCID: PMC10203415 DOI: 10.3389/fcell.2023.1113961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 04/24/2023] [Indexed: 05/27/2023] Open
Abstract
Employing history of science methods, including analyses of the scientific literature, archival documents, and interviews with scientists, this paper presents a history of lampreys in neurobiology from the 1830s to the present. We emphasize the lamprey's roles in helping to elucidate spinal cord regeneration mechanisms. Two attributes have long perpetuated studies of lampreys in neurobiology. First, they possess large neurons, including multiple classes of stereotypically located, 'identified' giant neurons in the brain, which project their large axons into the spinal cord. These giant neurons and their axonal fibers have facilitated electrophysiological recordings and imaging across biological scales, ranging from molecular to circuit-level analyses of nervous system structures and functions and including their roles in behavioral output. Second, lampreys have long been considered amongst the most basal extant vertebrates on the planet, so they have facilitated comparative studies pointing to conserved and derived characteristics of vertebrate nervous systems. These features attracted neurologists and zoologists to studies of lampreys between the 1830s and 1930s. But, the same two attributes also facilitated the rise of the lamprey in neural regeneration research after 1959, when biologists first wrote about the spontaneous, robust regeneration of some identified CNS axons in larvae after spinal cord injuries, coupled with recovery of normal swimming. Not only did large neurons promote fresh insights in the field, enabling studies incorporating multiple scales with existing and new technologies. But investigators also were able to attach a broad scope of relevance to their studies, interpreting them as suggesting conserved features of successful, and sometimes even unsuccessful, CNS regeneration. Lamprey research demonstrated that functional recovery takes place without the reformation of the original neuronal connections, for instance, by way of imperfect axonal regrowth and compensatory plasticity. Moreover, research performed in the lamprey model revealed that factors intrinsic to neurons are integral in promoting or hindering regeneration. As this work has helped illuminate why basal vertebrates accomplish CNS regeneration so well, whereas mammals do it so poorly, this history presents a case study in how biological and medical value have been, and could continue to be, gleaned from a non-traditional model organism for which molecular tools have been developed only relatively recently.
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Affiliation(s)
- Kathryn Maxson Jones
- Center for Medical Ethics and Health Policy, Baylor College of Medicine, Houston, TX, United States
- Department of History, Purdue University, West Lafayette, IN, United States
- Marine Biological Laboratory, The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Woods Hole, MA, United States
| | - Jennifer R. Morgan
- Marine Biological Laboratory, The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Woods Hole, MA, United States
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González-Llera L, Sobrido-Cameán D, Santos-Durán GN, Barreiro-Iglesias A. Full regeneration of descending corticotropin-releasing hormone axons after a complete spinal cord injury in lampreys. Comput Struct Biotechnol J 2022; 20:5690-5697. [PMID: 36320936 PMCID: PMC9596600 DOI: 10.1016/j.csbj.2022.10.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/14/2022] [Accepted: 10/14/2022] [Indexed: 11/16/2022] Open
Abstract
Sea lampreys are a vertebrate model of interest for the study of spontaneous axon regeneration after spinal cord injury (SCI). Axon regeneration research in lampreys has focused on the study of giant descending neurons, but less so on neurochemically-distinct descending neuronal populations with small caliber axons. Corticotropin-releasing hormone (CRH) is a neuropeptide that regulates the stress response or locomotion. CRH is also a neuropeptide of interest in the SCI context because descending CRHergic projections from the Barrington's nucleus control micturition behavior in mammals. Recent work from our group revealed that in sea lampreys the CRHergic innervation of the spinal cord is only of descending origin. Thus, the lack of intrinsic CRH spinal cord neurons provides the opportunity to analyze the regeneration of this descending system by using immunofluorescence methods. Here, we used an antibody against the sea lamprey mature CRH peptide, confocal microscopy, lightning adaptive deconvolution, and ImageJ to analyze the regenerative capacity of the descending CRH-immunoreactive (-ir) axons of larval sea lampreys after a complete SCI at the level of the fifth gill. At 10 weeks post-lesion, when behavioral analyses showed that injured animals had recovered normal appearing locomotion, our results revealed a full recovery of the number of CRH-ir profiles (axons) at the level of the sixth gill. Thus, the CRH descending axons of lampreys fully regenerate after a complete SCI. Our study provides a new model to study spontaneous and successful axonal regeneration in a specific neuronal type with small caliber axons by using simple immunohistochemical methods.
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Affiliation(s)
| | | | | | - Antón Barreiro-Iglesias
- Corresponding author at: CIBUS, Rúa Lope Gómez de Marzoa, Campus Vida, 15782 Santiago de Compostela, A Coruña, Spain.
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NPC transplantation rescues sci-driven cAMP/EPAC2 alterations, leading to neuroprotection and microglial modulation. Cell Mol Life Sci 2022; 79:455. [PMID: 35904607 PMCID: PMC9338125 DOI: 10.1007/s00018-022-04494-w] [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: 06/05/2022] [Revised: 07/07/2022] [Accepted: 07/17/2022] [Indexed: 11/17/2022]
Abstract
Neural progenitor cell (NPC) transplantation represents a promising treatment strategy for spinal cord injury (SCI); however, the underlying therapeutic mechanisms remain incompletely understood. We demonstrate that severe spinal contusion in adult rats causes transcriptional dysregulation, which persists from early subacute to chronic stages of SCI and affects nearly 20,000 genes in total tissue extracts. Functional analysis of this dysregulated transcriptome reveals the significant downregulation of cAMP signalling components immediately after SCI, involving genes such as EPAC2 (exchange protein directly activated by cAMP), PKA, BDNF, and CAMKK2. The ectopic transplantation of spinal cord-derived NPCs at acute or subacute stages of SCI induces a significant transcriptional impact in spinal tissue, as evidenced by the normalized expression of a large proportion of SCI-affected genes. The transcriptional modulation pattern driven by NPC transplantation includes the rescued expression of cAMP signalling genes, including EPAC2. We also explore how the sustained in vivo inhibition of EPAC2 downstream signalling via the intrathecal administration of ESI-05 for 1 week impacts therapeutic mechanisms involved in the NPC-mediated treatment of SCI. NPC transplantation in SCI rats in the presence and absence of ESI-05 administration prompts increased rostral cAMP levels; however, NPC and ESI-05 treated animals exhibit a significant reduction in EPAC2 mRNA levels compared to animals receiving only NPCs treatment. Compared with transplanted animals, NPCs + ESI-05 treatment increases the scar area (as shown by GFAP staining), polarizes microglia into an inflammatory phenotype, and increases the magnitude of the gap between NeuN + cells across the lesion. Overall, our results indicate that the NPC-associated therapeutic mechanisms in the context of SCI involve the cAMP pathway, which reduces inflammation and provides a more neuropermissive environment through an EPAC2-dependent mechanism.
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Rodemer W, Gallo G, Selzer ME. Mechanisms of Axon Elongation Following CNS Injury: What Is Happening at the Axon Tip? Front Cell Neurosci 2020; 14:177. [PMID: 32719586 PMCID: PMC7347967 DOI: 10.3389/fncel.2020.00177] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 05/22/2020] [Indexed: 12/12/2022] Open
Abstract
After an injury to the central nervous system (CNS), functional recovery is limited by the inability of severed axons to regenerate and form functional connections with appropriate target neurons beyond the injury. Despite tremendous advances in our understanding of the mechanisms of axon growth, and of the inhibitory factors in the injured CNS that prevent it, disappointingly little progress has been made in restoring function to human patients with CNS injuries, such as spinal cord injury (SCI), through regenerative therapies. Clearly, the large number of overlapping neuron-intrinsic and -extrinsic growth-inhibitory factors attenuates the benefit of neutralizing any one target. More daunting is the distances human axons would have to regenerate to reach some threshold number of target neurons, e.g., those that occupy one complete spinal segment, compared to the distances required in most experimental models, such as mice and rats. However, the difficulties inherent in studying mechanisms of axon regeneration in the mature CNS in vivo have caused researchers to rely heavily on extrapolation from studies of axon regeneration in peripheral nerve, or of growth cone-mediated axon development in vitro and in vivo. Unfortunately, evidence from several animal models, including the transected lamprey spinal cord, has suggested important differences between regeneration of mature CNS axons and growth of axons in peripheral nerve, or during embryonic development. Specifically, long-distance regeneration of severed axons may not involve the actin-myosin molecular motors that guide embryonic growth cones in developing axons. Rather, non-growth cone-mediated axon elongation may be required to propel injured axons in the mature CNS. If so, it may be necessary to use other experimental models to promote regeneration that is sufficient to contact a critical number of target neurons distal to a CNS lesion. This review examines the cytoskeletal underpinnings of axon growth, focusing on the elongating axon tip, to gain insights into how CNS axons respond to injury, and how this might affect the development of regenerative therapies for SCI and other CNS injuries.
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Affiliation(s)
- William Rodemer
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Gianluca Gallo
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States.,Department of Anatomy and Cell Biology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Michael E Selzer
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States.,Department of Neurology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
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Sobrido-Cameán D, Robledo D, Sánchez L, Rodicio MC, Barreiro-Iglesias A. Serotonin inhibits axonal regeneration of identifiable descending neurons after a complete spinal cord injury in lampreys. Dis Model Mech 2019; 12:dmm.037085. [PMID: 30709851 PMCID: PMC6398502 DOI: 10.1242/dmm.037085] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 01/22/2019] [Indexed: 02/06/2023] Open
Abstract
Classical neurotransmitters are mainly known for their roles as neuromodulators, but they also play important roles in the control of developmental and regenerative processes. Here, we used the lamprey model of spinal cord injury to study the effect of serotonin in axon regeneration at the level of individually identifiable descending neurons. Pharmacological and genetic manipulations after a complete spinal cord injury showed that endogenous serotonin inhibits axonal regeneration in identifiable descending neurons through the activation of serotonin 1A receptors and a subsequent decrease in cyclic adenosine monophosphate (cAMP) levels. RNA sequencing revealed that changes in the expression of genes that control axonal guidance could be a key factor determining the serotonin effects during regeneration. This study provides new targets of interest for research in non-regenerating mammalian models of traumatic central nervous system injuries and extends the known roles of serotonin signalling during neuronal regeneration.
This article has an associated First Person interview with the first author of the paper. Summary: Pharmacological and genetic manipulations show that endogenous serotonin inhibits axonal regeneration of individually identifiable descending neurons of lampreys after a complete spinal cord injury.
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Affiliation(s)
- Daniel Sobrido-Cameán
- Department of Functional Biology, CIBUS, Faculty of Biology, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Diego Robledo
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Midlothian EH25 9RG, UK
| | - Laura Sánchez
- Department of Genetics, University of Santiago de Compostela, Campus de Lugo, 27002 Lugo, Spain
| | - María Celina Rodicio
- Department of Functional Biology, CIBUS, Faculty of Biology, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Antón Barreiro-Iglesias
- Department of Functional Biology, CIBUS, Faculty of Biology, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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Benes JA, House KN, Burks FN, Conaway KP, Julien DP, Donley JP, Iyamu MA, McClellan AD. Regulation of axonal regeneration following spinal cord injury in the lamprey. J Neurophysiol 2017; 118:1439-1456. [PMID: 28469003 DOI: 10.1152/jn.00986.2016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 04/24/2017] [Accepted: 04/29/2017] [Indexed: 12/12/2022] Open
Abstract
Following rostral spinal cord injury (SCI) in larval lampreys, injured descending brain neurons, particularly reticulospinal (RS) neurons, regenerate their axons, and locomotor behavior recovers in a few weeks. However, axonal regeneration of descending brain neurons is mostly limited to relatively short distances, but the mechanisms for incomplete axonal regeneration are unclear. First, lampreys with rostral SCI exhibited greater axonal regeneration of descending brain neurons, including RS neurons, as well as more rapid recovery of locomotor muscle activity right below the lesion site, compared with animals with caudal SCI. In addition, following rostral SCI, most injured RS neurons displayed the "injury phenotype," whereas following caudal SCI, most injured neurons displayed normal electrical properties. Second, following rostral SCI, at cold temperatures (~4-5°C), axonal transport was suppressed, axonal regeneration and behavioral recovery were blocked, and injured RS neurons displayed normal electrical properties. Cold temperatures appear to prevent injured RS neurons from detecting and/or responding to SCI. It is hypothesized that following rostral SCI, injured descending brain neurons are strongly stimulated to regenerate their axons, presumably because of elimination of spinal synapses and reduced neurotrophic support. However, when these neurons regenerate their axons and make synapses right below the lesion site, restoration of neurotrophic support very likely suppress further axonal regeneration. In contrast, caudal SCI is a weak stimulus for axonal regeneration, presumably because of spared synapses above the lesion site. These results may have implications for mammalian SCI, which can spare synapses above the lesion site for supraspinal descending neurons and propriospinal neurons.NEW & NOTEWORTHY Lampreys with rostral spinal cord injury (SCI) exhibited greater axonal regeneration of descending brain neurons and more rapid recovery of locomotor muscle activity below the lesion site compared with animals with caudal SCI. In addition, following rostral SCI, most injured reticulospinal (RS) neurons displayed the "injury phenotype," whereas following caudal SCI, most injured neurons had normal electrical properties. We hypothesize that following caudal SCI, the spared synapses of injured RS neurons might limit axonal regeneration and behavioral recovery.
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Affiliation(s)
- Jessica A Benes
- Division of Biological Sciences, University of Missouri, Columbia, Missouri; and
| | - Kylie N House
- Division of Biological Sciences, University of Missouri, Columbia, Missouri; and
| | - Frank N Burks
- Division of Biological Sciences, University of Missouri, Columbia, Missouri; and
| | - Kris P Conaway
- Division of Biological Sciences, University of Missouri, Columbia, Missouri; and
| | - Donald P Julien
- Division of Biological Sciences, University of Missouri, Columbia, Missouri; and
| | - Jeffrey P Donley
- Division of Biological Sciences, University of Missouri, Columbia, Missouri; and
| | - Michael A Iyamu
- Division of Biological Sciences, University of Missouri, Columbia, Missouri; and
| | - Andrew D McClellan
- Division of Biological Sciences, University of Missouri, Columbia, Missouri; and .,Interdisciplinary Neuroscience Program, University of Missouri, Columbia, Missouri
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9
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Learning to swim, again: Axon regeneration in fish. Exp Neurol 2017; 287:318-330. [DOI: 10.1016/j.expneurol.2016.02.022] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 02/25/2016] [Accepted: 02/27/2016] [Indexed: 01/10/2023]
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10
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Xia T, Huang B, Ni S, Gao L, Wang J, Wang J, Chen A, Zhu S, Wang B, Li G, Zhu S, Li X. The combination of db-cAMP and ChABC with poly(propylene carbonate) microfibers promote axonal regenerative sprouting and functional recovery after spinal cord hemisection injury. Biomed Pharmacother 2016; 86:354-362. [PMID: 28011383 DOI: 10.1016/j.biopha.2016.12.045] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2016] [Revised: 12/08/2016] [Accepted: 12/08/2016] [Indexed: 12/27/2022] Open
Abstract
This study describes the use of poly(propylene carbonate) (PPC) electrospun microfibres impregnated with a combination of dibutyryl cyclic adenosine monophosphate (db-cAMP) and chondroitinase ABC (ChABC) in the treatment of right-side hemisected spinal cord injury (SCI). Release of db-cAMP and/or ChABC from the microfibres was assessed in vitro using high-performance liquid chromatography (HPLC). Drug-impregnated microfibres were implanted into the hemisected thoracic spinal cord of rats, and treatment was evaluated using functional recovery examinations and immunohistochemistry. Our results demonstrated that the microfibres containing db-cAMP and/or ChABC displayed a stable and prolonged release of each agent. Sustained delivery of db-cAMP and/or ChABC was found to promote axonal regenerative sprouting, functional recovery, and reduced glial scar formation when compared to untreated control animals. The combination of both db-cAMP and ChABC was determined to be more effective than using either drug alone in the treatment of SCI. These findings demonstrate the feasibility of using PPC electrospun microfibres for multi-drug combination therapy in SCI.
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Affiliation(s)
- Tongliang Xia
- Department of Neurosurgery, Qilu Hospital of Shandong University and Brain Science Research Institute, Shandong University, 107# Wenhua Xi Road, Jinan, 250012, PR China
| | - Bin Huang
- Department of Neurosurgery, Qilu Hospital of Shandong University and Brain Science Research Institute, Shandong University, 107# Wenhua Xi Road, Jinan, 250012, PR China
| | - Shilei Ni
- Department of Neurosurgery, Qilu Hospital of Shandong University and Brain Science Research Institute, Shandong University, 107# Wenhua Xi Road, Jinan, 250012, PR China
| | - Lei Gao
- Jiyang County People's Hospital of Shandong Provence, 9# Xinyuan Street, Jinyang County, Jinan, 251400, PR China
| | - Jiangang Wang
- Department of Neurosurgery, Qilu Hospital of Shandong University and Brain Science Research Institute, Shandong University, 107# Wenhua Xi Road, Jinan, 250012, PR China
| | - Jian Wang
- Department of Neurosurgery, Qilu Hospital of Shandong University and Brain Science Research Institute, Shandong University, 107# Wenhua Xi Road, Jinan, 250012, PR China; Department of Biomedicine, University of Bergen, Jonas Lies Vei 91, 5009 Bergen, Norway
| | - Anjing Chen
- Department of Neurosurgery, Qilu Hospital of Shandong University and Brain Science Research Institute, Shandong University, 107# Wenhua Xi Road, Jinan, 250012, PR China
| | - Shaowei Zhu
- Department of Neurology, Qilu Hospital of Shandong University, 107# Wenhua Xi Road, Jinan, 250012, PR China
| | - Benlin Wang
- Department of Neurosurgery, Qilu Hospital of Shandong University and Brain Science Research Institute, Shandong University, 107# Wenhua Xi Road, Jinan, 250012, PR China
| | - Gang Li
- Department of Neurosurgery, Qilu Hospital of Shandong University and Brain Science Research Institute, Shandong University, 107# Wenhua Xi Road, Jinan, 250012, PR China
| | - Shugan Zhu
- Department of Neurosurgery, Qilu Hospital of Shandong University and Brain Science Research Institute, Shandong University, 107# Wenhua Xi Road, Jinan, 250012, PR China
| | - Xingang Li
- Department of Neurosurgery, Qilu Hospital of Shandong University and Brain Science Research Institute, Shandong University, 107# Wenhua Xi Road, Jinan, 250012, PR China.
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Moldovan M, Alvarez S, Rosberg MR, Krarup C. Persistent alterations in active and passive electrical membrane properties of regenerated nerve fibers of man and mice. Eur J Neurosci 2015; 43:388-403. [DOI: 10.1111/ejn.13047] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 07/31/2015] [Accepted: 08/13/2015] [Indexed: 12/12/2022]
Affiliation(s)
- Mihai Moldovan
- Department of Neuroscience and Pharmacology; University of Copenhagen; Copenhagen Denmark
- Department of Clinical Neurophysiology; NF3063 Rigshospitalet 9 Blegdamsvej 2100 Copenhagen Denmark
| | - Susana Alvarez
- Department of Neuroscience and Pharmacology; University of Copenhagen; Copenhagen Denmark
- Department of Clinical Neurophysiology; NF3063 Rigshospitalet 9 Blegdamsvej 2100 Copenhagen Denmark
| | - Mette R. Rosberg
- Department of Neuroscience and Pharmacology; University of Copenhagen; Copenhagen Denmark
- Department of Clinical Neurophysiology; NF3063 Rigshospitalet 9 Blegdamsvej 2100 Copenhagen Denmark
| | - Christian Krarup
- Department of Neuroscience and Pharmacology; University of Copenhagen; Copenhagen Denmark
- Department of Clinical Neurophysiology; NF3063 Rigshospitalet 9 Blegdamsvej 2100 Copenhagen Denmark
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12
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Kuffler DP. Platelet-Rich Plasma Promotes Axon Regeneration, Wound Healing, and Pain Reduction: Fact or Fiction. Mol Neurobiol 2015; 52:990-1014. [PMID: 26048672 DOI: 10.1007/s12035-015-9251-x] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Indexed: 11/25/2022]
Abstract
Platelet-rich plasma (PRP) has been tested in vitro, in animal models, and clinically for its efficacy in enhancing the rate of wound healing, reducing pain associated with injuries, and promoting axon regeneration. Although extensive data indicate that PRP-released factors induce these effects, the claims are often weakened because many studies were not rigorous or controlled, the data were limited, and other studies yielded contrary results. Critical to assessing whether PRP is effective are the large number of variables in these studies, including the method of PRP preparation, which influences the composition of PRP; type of application; type of wounds; target tissues; and diverse animal models and clinical studies. All these variables raise the question of whether one can anticipate consistent influences and raise the possibility that most of the results are correct under the circumstances where PRP was tested. This review examines evidence on the potential influences of PRP and whether PRP-released factors could induce the reported influences and concludes that the preponderance of evidence suggests that PRP has the capacity to induce all the claimed influences, although this position cannot be definitively argued. Well-defined and rigorously controlled studies of the potential influences of PRP are required in which PRP is isolated and applied using consistent techniques, protocols, and models. Finally, it is concluded that, because of the purported benefits of PRP administration and the lack of adverse events, further animal and clinical studies should be performed to explore the potential influences of PRP.
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Affiliation(s)
- Damien P Kuffler
- Institute of Neurobiology, University of Puerto Rico, Medical Sciences Campus, 201 Blvd. Del Valle, San Juan, 00901, Puerto Rico,
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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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Cyclic AMP promotes axon regeneration, lesion repair and neuronal survival in lampreys after spinal cord injury. Exp Neurol 2013; 250:31-42. [PMID: 24041988 DOI: 10.1016/j.expneurol.2013.09.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 09/03/2013] [Accepted: 09/08/2013] [Indexed: 01/10/2023]
Abstract
Axon regeneration after spinal cord injury in mammals is inadequate to restore function, illustrating the need to design better strategies for improving outcomes. Increasing the levels of the second messenger cyclic adenosine monophosphate (cAMP) after spinal cord injury enhances axon regeneration across a wide variety of species, making it an excellent candidate molecule that has therapeutic potential. However, several important aspects of the cellular and molecular mechanisms by which cAMP enhances axon regeneration are still unclear, such as how cAMP affects axon growth patterns, the molecular components within growing axon tips, the lesion scar, and neuronal survival. To address these points, we took advantage of the large, identified reticulospinal (RS) neurons in lamprey, a vertebrate that exhibits robust axon regeneration after a complete spinal cord transection. Application of a cAMP analog, db-cAMP, at the time of spinal cord transection increased the number of axons that regenerated across the lesion site. Db-cAMP also promoted axons to regenerate in straighter paths, prevented abnormal axonal growth patterns, increased the levels of synaptotagmin within axon tips, and increased the number of axotomized neurons that survived after spinal cord injury, thereby increasing the pool of neurons available for regeneration. There was also a transient increase in the number of microglia/macrophages and improved repair of the lesion site. Taken together, these data reveal several new features of the cellular and molecular mechanisms underlying cAMP-mediated enhancement of axon regeneration, further emphasizing the positive roles for this conserved pathway.
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