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Amar Kumar P, Dulin JN. Implications of regional identity for neural stem and progenitor cell transplantation in the injured or diseased nervous system. Neural Regen Res 2024; 19:715-716. [PMID: 37843199 PMCID: PMC10664136 DOI: 10.4103/1673-5374.382236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 06/08/2023] [Accepted: 06/29/2023] [Indexed: 10/17/2023] Open
Affiliation(s)
| | - Jennifer N. Dulin
- Department of Biology, Texas A&M University, College Station, TX, USA
- Texas A&M Institute for Neuroscience, Texas A&M University, College Station, TX, USA
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2
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Jagrit V, Koffler J, Dulin JN. Combinatorial strategies for cell transplantation in traumatic spinal cord injury. Front Neurosci 2024; 18:1349446. [PMID: 38510468 PMCID: PMC10951004 DOI: 10.3389/fnins.2024.1349446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 02/20/2024] [Indexed: 03/22/2024] Open
Abstract
Spinal cord injury (SCI) substantially reduces the quality of life of affected individuals. Recovery of function is therefore a primary concern of the patient population and a primary goal for therapeutic interventions. Currently, even with growing numbers of clinical trials, there are still no effective treatments that can improve neurological outcomes after SCI. A large body of work has demonstrated that transplantation of neural stem/progenitor cells (NSPCs) can promote regeneration of the injured spinal cord by providing new neurons that can integrate into injured host neural circuitry. Despite these promising findings, the degree of functional recovery observed after NSPC transplantation remains modest. It is evident that treatment of such a complex injury cannot be addressed with a single therapeutic approach. In this mini-review, we discuss combinatorial strategies that can be used along with NSPC transplantation to promote spinal cord regeneration. We begin by introducing bioengineering and neuromodulatory approaches, and highlight promising work using these strategies in integration with NSPCs transplantation. The future of NSPC transplantation will likely include a multi-factorial approach, combining stem cells with biomaterials and/or neuromodulation as a promising treatment for SCI.
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Affiliation(s)
- Vipin Jagrit
- Department of Biology, Texas A&M University, College Station, TX, United States
| | - Jacob Koffler
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, United States
- Veterans Affairs Medical Center, San Diego, CA, United States
| | - Jennifer N. Dulin
- Department of Biology, Texas A&M University, College Station, TX, United States
- Texas A&M Institute for Neuroscience, Texas A&M University, College Station, TX, United States
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3
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Zholudeva LV, Fortino T, Agrawal A, Vila OF, Williams M, McDevitt T, Lane MA, Srivastava D. Human spinal interneurons repair the injured spinal cord through synaptic integration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.11.575264. [PMID: 38260390 PMCID: PMC10802598 DOI: 10.1101/2024.01.11.575264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Advances in cell therapy offer promise for some of the most devastating neural injuries, including spinal cord injury (SCI). Endogenous VSX2-expressing spinal V2a interneurons have been implicated as a key component in plasticity and therapeutically driven recovery post-SCI. While transplantation of generic V2a neurons may have therapeutic value, generation of human spinal V2a neurons with rostro-caudal specificity and assessment of their functional synaptic integration with the injured spinal cord has been elusive. Here, we efficiently differentiated optogenetically engineered cervical V2a spinal interneurons (SpINs) from human induced pluripotent stem cells and tested their capacity to form functional synapses with injured diaphragm motor networks in a clinically-relevant sub-acute model of cervical contusion injury. Neuroanatomical tracing and immunohistochemistry demonstrated transplant integration and synaptic connectivity with injured host tissue. Optogenetic activation of transplanted human V2a SpINs revealed functional synaptic connectivity to injured host circuits, culminating in improved diaphragm activity assessed by electromyography. Furthermore, optogenetic activation of host supraspinal pathways revealed functional innervation of transplanted cells by host neurons, which also led to enhanced diaphragm contraction indicative of a functional neuronal relay. Single cell analyses pre- and post-transplantation suggested the in vivo environment resulted in maturation of cervical SpINs that mediate the formation of neuronal relays, as well as differentiation of glial progenitors involved in repair of the damaged spinal cord. This study rigorously demonstrates feasibility of generating human cervical spinal V2a interneurons that develop functional host-transplant and transplant-host connectivity resulting in improved muscle activity post-SCI.
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4
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Silverstein AL, Lawson KG, Farhadi HF, Alilain WJ. Contrasting Experimental Rodent Aftercare With Human Clinical Treatment for Cervical Spinal Cord Injury: Bridging the Translational "Valley of Death". J Neurotrauma 2023; 40:2469-2486. [PMID: 37772694 PMCID: PMC10698787 DOI: 10.1089/neu.2023.0314] [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] [Indexed: 09/30/2023] Open
Abstract
More than half of all spinal cord injuries (SCIs) occur at the cervical level and often lead to life-threatening breathing motor dysfunction. The C2 hemisection (C2Hx) and high cervical contusion mouse and rat models of SCI are widely utilized both to understand the pathological effects of SCI and to develop potential therapies. Despite rigorous research effort, pre-clinical therapeutics studied in those animal models of SCI sometimes fail when evaluated in the clinical setting. Differences between standard-of-care treatment for acute SCI administered to clinical populations and experimental animal models of SCI could influence the heterogeneity of outcome between pre-clinical and clinical studies. In this review, we have summarized both the standard clinical interventions used to treat patients with cervical SCI and the various veterinary aftercare protocols used to care for rats and mice after experimentally induced C2Hx and high cervical contusion models of SCI. Through this analysis, we have identified areas of marked dissimilarity between clinical and veterinary protocols and suggest the modification of pre-clinical animal care particularly with respect to analgesia, anticoagulative measures, and stress ulcer prophylaxis. In our discussion, we intend to inspire consideration of potential changes to aftercare for animal subjects of experimental SCI that may help to bridge the translational "Valley of Death" and ultimately contribute more effectively to finding treatments capable of restoring independent breathing function to persons with cervical SCI.
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Affiliation(s)
- Aaron L. Silverstein
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Katelyn G. Lawson
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - H. Francis Farhadi
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
- Department of Neurosurgery, Spinal Cord and Brain Injury Research Center, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Warren J. Alilain
- Department of Neuroscience, Spinal Cord and Brain Injury Research Center, College of Medicine, University of Kentucky, Lexington, Kentucky, USA
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5
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Michel-Flutot P, Lane MA, Lepore AC, Vinit S. Therapeutic Strategies Targeting Respiratory Recovery after Spinal Cord Injury: From Preclinical Development to Clinical Translation. Cells 2023; 12:1519. [PMID: 37296640 PMCID: PMC10252981 DOI: 10.3390/cells12111519] [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: 04/14/2023] [Revised: 05/15/2023] [Accepted: 05/29/2023] [Indexed: 06/12/2023] Open
Abstract
High spinal cord injuries (SCIs) lead to permanent functional deficits, including respiratory dysfunction. Patients living with such conditions often rely on ventilatory assistance to survive, and even those that can be weaned continue to suffer life-threatening impairments. There is currently no treatment for SCI that is capable of providing complete recovery of diaphragm activity and respiratory function. The diaphragm is the main inspiratory muscle, and its activity is controlled by phrenic motoneurons (phMNs) located in the cervical (C3-C5) spinal cord. Preserving and/or restoring phMN activity following a high SCI is essential for achieving voluntary control of breathing. In this review, we will highlight (1) the current knowledge of inflammatory and spontaneous pro-regenerative processes occurring after SCI, (2) key therapeutics developed to date, and (3) how these can be harnessed to drive respiratory recovery following SCIs. These therapeutic approaches are typically first developed and tested in relevant preclinical models, with some of them having been translated into clinical studies. A better understanding of inflammatory and pro-regenerative processes, as well as how they can be therapeutically manipulated, will be the key to achieving optimal functional recovery following SCIs.
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Affiliation(s)
- Pauline Michel-Flutot
- END-ICAP, UVSQ, Inserm, Université Paris-Saclay, 78000 Versailles, France;
- Department of Neuroscience, Jefferson Synaptic Biology Center, Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA;
| | - Michael A. Lane
- Marion Murray Spinal Cord Research Center, Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA;
| | - Angelo C. Lepore
- Department of Neuroscience, Jefferson Synaptic Biology Center, Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA;
| | - Stéphane Vinit
- END-ICAP, UVSQ, Inserm, Université Paris-Saclay, 78000 Versailles, France;
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6
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Aceves M, Tucker A, Chen J, Vo K, Moses J, Amar Kumar P, Thomas H, Miranda D, Dampf G, Dietz V, Chang M, Lukose A, Jang J, Nadella S, Gillespie T, Trevino C, Buxton A, Pritchard AL, Green P, McCreedy DA, Dulin JN. Developmental stage of transplanted neural progenitor cells influences anatomical and functional outcomes after spinal cord injury in mice. Commun Biol 2023; 6:544. [PMID: 37208439 PMCID: PMC10199026 DOI: 10.1038/s42003-023-04893-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 05/02/2023] [Indexed: 05/21/2023] Open
Abstract
Neural progenitor cell (NPC) transplantation is a promising therapeutic strategy for replacing lost neurons following spinal cord injury (SCI). However, how graft cellular composition influences regeneration and synaptogenesis of host axon populations, or recovery of motor and sensory functions after SCI, is poorly understood. We transplanted developmentally-restricted spinal cord NPCs, isolated from E11.5-E13.5 mouse embryos, into sites of adult mouse SCI and analyzed graft axon outgrowth, cellular composition, host axon regeneration, and behavior. Earlier-stage grafts exhibited greater axon outgrowth, enrichment for ventral spinal cord interneurons and Group-Z spinal interneurons, and enhanced host 5-HT+ axon regeneration. Later-stage grafts were enriched for late-born dorsal horn interneuronal subtypes and Group-N spinal interneurons, supported more extensive host CGRP+ axon ingrowth, and exacerbated thermal hypersensitivity. Locomotor function was not affected by any type of NPC graft. These findings showcase the role of spinal cord graft cellular composition in determining anatomical and functional outcomes following SCI.
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Affiliation(s)
- Miriam Aceves
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
- Texas A&M Institute for Neuroscience, Texas A&M University, College Station, TX, 77843, USA
| | - Ashley Tucker
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
- Texas A&M Institute for Neuroscience, Texas A&M University, College Station, TX, 77843, USA
| | - Joseph Chen
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Katie Vo
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Joshua Moses
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | | | - Hannah Thomas
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Diego Miranda
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Gabrielle Dampf
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Valerie Dietz
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Matthew Chang
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Aleena Lukose
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Julius Jang
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Sneha Nadella
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Tucker Gillespie
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Christian Trevino
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Andrew Buxton
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843, USA
| | - Anna L Pritchard
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843, USA
| | | | - Dylan A McCreedy
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
- Texas A&M Institute for Neuroscience, Texas A&M University, College Station, TX, 77843, USA
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, 77843, USA
| | - Jennifer N Dulin
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA.
- Texas A&M Institute for Neuroscience, Texas A&M University, College Station, TX, 77843, USA.
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7
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Khaing ZZ, Chen JY, Safarians G, Ezubeik S, Pedroncelli N, Duquette RD, Prasse T, Seidlits SK. Clinical Trials Targeting Secondary Damage after Traumatic Spinal Cord Injury. Int J Mol Sci 2023; 24:3824. [PMID: 36835233 PMCID: PMC9960771 DOI: 10.3390/ijms24043824] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 02/06/2023] [Accepted: 02/09/2023] [Indexed: 02/17/2023] Open
Abstract
Spinal cord injury (SCI) often causes loss of sensory and motor function resulting in a significant reduction in quality of life for patients. Currently, no therapies are available that can repair spinal cord tissue. After the primary SCI, an acute inflammatory response induces further tissue damage in a process known as secondary injury. Targeting secondary injury to prevent additional tissue damage during the acute and subacute phases of SCI represents a promising strategy to improve patient outcomes. Here, we review clinical trials of neuroprotective therapeutics expected to mitigate secondary injury, focusing primarily on those in the last decade. The strategies discussed are broadly categorized as acute-phase procedural/surgical interventions, systemically delivered pharmacological agents, and cell-based therapies. In addition, we summarize the potential for combinatorial therapies and considerations.
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Affiliation(s)
- Zin Z. Khaing
- Department of Neurological Surgery, University of Washington, Seattle, WA 98195, USA
| | - Jessica Y. Chen
- Department of Bioengineering, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Gevick Safarians
- Department of Bioengineering, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Sohib Ezubeik
- Department of Bioengineering, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Nicolas Pedroncelli
- Department of Bioengineering, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Rebecca D. Duquette
- Department of Bioengineering, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX 78712, USA
| | - Tobias Prasse
- Department of Neurological Surgery, University of Washington, Seattle, WA 98195, USA
- Department of Orthopedics and Trauma Surgery, University of Cologne, 50931 Cologne, Germany
| | - Stephanie K. Seidlits
- Department of Bioengineering, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX 78712, USA
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8
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Locke KC, Randelman ML, Hoh DJ, Zholudeva LV, Lane MA. Respiratory plasticity following spinal cord injury: perspectives from mouse to man. Neural Regen Res 2022; 17:2141-2148. [PMID: 35259820 PMCID: PMC9083159 DOI: 10.4103/1673-5374.335839] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 09/18/2021] [Accepted: 10/20/2021] [Indexed: 12/03/2022] Open
Abstract
The study of respiratory plasticity in animal models spans decades. At the bench, researchers use an array of techniques aimed at harnessing the power of plasticity within the central nervous system to restore respiration following spinal cord injury. This field of research is highly clinically relevant. People living with cervical spinal cord injury at or above the level of the phrenic motoneuron pool at spinal levels C3-C5 typically have significant impairments in breathing which may require assisted ventilation. Those who are ventilator dependent are at an increased risk of ventilator-associated co-morbidities and have a drastically reduced life expectancy. Pre-clinical research examining respiratory plasticity in animal models has laid the groundwork for clinical trials. Despite how widely researched this injury is in animal models, relatively few treatments have broken through the preclinical barrier. The three goals of this present review are to define plasticity as it pertains to respiratory function post-spinal cord injury, discuss plasticity models of spinal cord injury used in research, and explore the shift from preclinical to clinical research. By investigating current targets of respiratory plasticity research, we hope to illuminate preclinical work that can influence future clinical investigations and the advancement of treatments for spinal cord injury.
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Affiliation(s)
- Katherine C. Locke
- Department of Neurobiology & Anatomy, Drexel University, Philadelphia, PA, USA
- Marion Murray Spinal Cord Research Center, Philadelphia, PA, USA
| | - Margo L. Randelman
- Department of Neurobiology & Anatomy, Drexel University, Philadelphia, PA, USA
- Marion Murray Spinal Cord Research Center, Philadelphia, PA, USA
| | - Daniel J. Hoh
- Lillian S. Wells Department of Neurosurgery, University of Florida, Gainesville, FL, USA
| | - Lyandysha V. Zholudeva
- Marion Murray Spinal Cord Research Center, Philadelphia, PA, USA
- Cardiovascular Disease, Gladstone Institutes, San Francisco, CA, USA
| | - Michael A. Lane
- Department of Neurobiology & Anatomy, Drexel University, Philadelphia, PA, USA
- Marion Murray Spinal Cord Research Center, Philadelphia, PA, USA
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9
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Cell transplantation to repair the injured spinal cord. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2022; 166:79-158. [PMID: 36424097 PMCID: PMC10008620 DOI: 10.1016/bs.irn.2022.09.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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10
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Fortino TA, Randelman ML, Hall AA, Singh J, Bloom DC, Engel E, Hoh DJ, Hou S, Zholudeva LV, Lane MA. Transneuronal tracing to map connectivity in injured and transplanted spinal networks. Exp Neurol 2022; 351:113990. [DOI: 10.1016/j.expneurol.2022.113990] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 12/09/2021] [Accepted: 01/20/2022] [Indexed: 11/24/2022]
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11
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Allen LL, Nichols NL, Asa ZA, Emery AT, Ciesla MC, Santiago JV, Holland AE, Mitchell GS, Gonzalez-Rothi EJ. Phrenic motor neuron survival below cervical spinal cord hemisection. Exp Neurol 2021; 346:113832. [PMID: 34363808 PMCID: PMC9065093 DOI: 10.1016/j.expneurol.2021.113832] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 07/31/2021] [Accepted: 08/02/2021] [Indexed: 02/04/2023]
Abstract
Cervical spinal cord injury (cSCI) severs bulbospinal projections to respiratory motor neurons, paralyzing respiratory muscles below the injury. C2 spinal hemisection (C2Hx) is a model of cSCI often used to study spontaneous and induced plasticity and breathing recovery post-injury. One key assumption is that C2Hx dennervates motor neurons below the injury, but does not affect their survival. However, a recent study reported substantial bilateral motor neuron death caudal to C2Hx. Since phrenic motor neuron (PMN) death following C2Hx would have profound implications for therapeutic strategies designed to target spared neural circuits, we tested the hypothesis that C2Hx minimally impacts PMN survival. Using improved retrograde tracing methods, we observed no loss of PMNs at 2- or 8-weeks post-C2Hx. We also observed no injury-related differences in ChAT or NeuN immunolabeling within labelled PMNs. Although we found no evidence of PMN loss following C2Hx, we cannot rule out neuronal loss in other motor pools. These findings address an essential prerequisite for studies that utilize C2Hx as a model to explore strategies for inducing plasticity and/or regeneration within the phrenic motor system, as they provide important insights into the viability of phrenic motor neurons as therapeutic targets after high cervical injury.
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Affiliation(s)
- Latoya L Allen
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Nicole L Nichols
- Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65211, USA
| | - Zachary A Asa
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | | | - Marissa C Ciesla
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Juliet V Santiago
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Ashley E Holland
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Gordon S Mitchell
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Elisa J Gonzalez-Rothi
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA.
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12
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Neural Stem Cells: Promoting Axonal Regeneration and Spinal Cord Connectivity. Cells 2021; 10:cells10123296. [PMID: 34943804 PMCID: PMC8699545 DOI: 10.3390/cells10123296] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 11/16/2021] [Accepted: 11/16/2021] [Indexed: 11/17/2022] Open
Abstract
Spinal cord injury (SCI) leads to irreversible functional impairment caused by neuronal loss and the disruption of neuronal connections across the injury site. While several experimental strategies have been used to minimize tissue damage and to enhance axonal growth and regeneration, the corticospinal projection, which is the most important voluntary motor system in humans, remains largely refractory to regenerative therapeutic interventions. To date, one of the most promising pre-clinical therapeutic strategies has been neural stem cell (NSC) therapy for SCI. Over the last decade we have found that host axons regenerate into spinal NSC grafts placed into sites of SCI. These regenerating axons form synapses with the graft, and the graft in turn extends very large numbers of new axons from the injury site over long distances into the distal spinal cord. Here we discuss the pathophysiology of SCI that makes the spinal cord refractory to spontaneous regeneration, the most recent findings of neural stem cell therapy for SCI, how it has impacted motor systems including the corticospinal tract and the implications for sensory feedback.
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13
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Zholudeva LV, Jin Y, Qiang L, Lane MA, Fischer I. Preparation of Neural Stem Cells and Progenitors: Neuronal Production and Grafting Applications. Methods Mol Biol 2021; 2311:73-108. [PMID: 34033079 PMCID: PMC10074836 DOI: 10.1007/978-1-0716-1437-2_7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Neural stem cells (NSCs) are a valuable tool for the study of neural development and function as well as an important source of cell transplantation strategies for neural disease. NSCs can be used to study how neurons acquire distinct phenotypes and how the interactions between neurons and glial cells in the developing nervous system shape the structure and function of the CNS. NSCs can also be used for cell replacement therapies following CNS injury targeting astrocytes, oligodendrocytes, and neurons. With the availability of patient-derived induced pluripotent stem cells (iPSCs), neurons prepared from NSCs can be used to elucidate the molecular basis of neurological disorders leading to potential treatments. Although NSCs can be derived from different species and many sources, including embryonic stem cells (ESCs), iPSCs, adult CNS, and direct reprogramming of nonneural cells, isolating primary NSCs directly from fetal tissue is still the most common technique for preparation and study of neurons. Regardless of the source of tissue, similar techniques are used to maintain NSCs in culture and to differentiate NSCs toward mature neural lineages. This chapter will describe specific methods for isolating and characterizing multipotent NSCs and neural precursor cells (NPCs) from embryonic rat CNS tissue (mostly spinal cord) and from human ESCs and iPSCs as well as NPCs prepared by reprogramming. NPCs can be separated into neuronal and glial restricted progenitors (NRP and GRP, respectively) and used to reliably produce neurons or glial cells both in vitro and following transplantation into the adult CNS. This chapter will describe in detail the methods required for the isolation, propagation, storage, and differentiation of NSCs and NPCs isolated from rat and mouse spinal cords for subsequent in vitro or in vivo studies as well as new methods associated with ESCs, iPSCs, and reprogramming.
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Affiliation(s)
- Lyandysha V Zholudeva
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Ying Jin
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Liang Qiang
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Michael A Lane
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Itzhak Fischer
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA.
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14
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Zholudeva LV, Abraira VE, Satkunendrarajah K, McDevitt TC, Goulding MD, Magnuson DSK, Lane MA. Spinal Interneurons as Gatekeepers to Neuroplasticity after Injury or Disease. J Neurosci 2021; 41:845-854. [PMID: 33472820 PMCID: PMC7880285 DOI: 10.1523/jneurosci.1654-20.2020] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 12/15/2020] [Accepted: 12/17/2020] [Indexed: 12/15/2022] Open
Abstract
Spinal interneurons are important facilitators and modulators of motor, sensory, and autonomic functions in the intact CNS. This heterogeneous population of neurons is now widely appreciated to be a key component of plasticity and recovery. This review highlights our current understanding of spinal interneuron heterogeneity, their contribution to control and modulation of motor and sensory functions, and how this role might change after traumatic spinal cord injury. We also offer a perspective for how treatments can optimize the contribution of interneurons to functional improvement.
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Affiliation(s)
| | - Victoria E Abraira
- Department of Cell Biology & Neuroscience, Rutgers University, The State University of New Jersey, New Jersey, 08854
| | - Kajana Satkunendrarajah
- Departments of Neurosurgery and Physiology, Medical College of Wisconsin, Wisconsin, 53226
- Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, 53295
| | - Todd C McDevitt
- Gladstone Institutes, San Francisco, California, 94158
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California, 94143
| | | | - David S K Magnuson
- University of Louisville, Kentucky Spinal Cord Injury Research Center, Louisville, Kentucky, 40208
| | - Michael A Lane
- Department of Neurobiology and Anatomy, and the Marion Murray Spinal Cord Research Center, Drexel University, Philadelphia, Pennsylvania, 19129
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15
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Fischer I, Dulin JN, Lane MA. Transplanting neural progenitor cells to restore connectivity after spinal cord injury. Nat Rev Neurosci 2020; 21:366-383. [PMID: 32518349 PMCID: PMC8384139 DOI: 10.1038/s41583-020-0314-2] [Citation(s) in RCA: 136] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/30/2020] [Indexed: 12/12/2022]
Abstract
Spinal cord injury remains a scientific and therapeutic challenge with great cost to individuals and society. The goal of research in this field is to find a means of restoring lost function. Recently we have seen considerable progress in understanding the injury process and the capacity of CNS neurons to regenerate, as well as innovations in stem cell biology. This presents an opportunity to develop effective transplantation strategies to provide new neural cells to promote the formation of new neuronal networks and functional connectivity. Past and ongoing clinical studies have demonstrated the safety of cell therapy, and preclinical research has used models of spinal cord injury to better elucidate the underlying mechanisms through which donor cells interact with the host and thus increase long-term efficacy. While a variety of cell therapies have been explored, we focus here on the use of neural progenitor cells obtained or derived from different sources to promote connectivity in sensory, motor and autonomic systems.
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Affiliation(s)
- Itzhak Fischer
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA.
| | - Jennifer N Dulin
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - Michael A Lane
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA
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Abstract
Cellular transplantation for repair of the injured spinal cord has a rich history with strategies focused on neuroprotection, immunomodulation, and neural reconstruction. The goal of the present review is to provide a concise overview and discussion of five key themes that have become important considerations for rebuilding functional neural networks. The questions raised include: (i) who are the donor cells selected for transplantation, (ii) what is the intended target for repair, (iii) when is the optimal time for transplantation, (iv) where should the cells be delivered, and lastly (v) why does cell transplantation remain an attractive candidate for promoting neural repair after injury? Recent developments in neurobiology and engineering now enable us to start addressing these questions with multidisciplinary expertise and methods.
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Affiliation(s)
- Lyandysha V Zholudeva
- 1 Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, PA, USA.,2 The Spinal Cord Research Center, College of Medicine, Drexel University, Philadelphia, PA, USA
| | - Michael A Lane
- 1 Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, PA, USA.,2 The Spinal Cord Research Center, College of Medicine, Drexel University, Philadelphia, PA, USA
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17
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Zholudeva LV, Lane MA. Choosing the right cell for spinal cord repair. J Neurosci Res 2018; 97:109-111. [PMID: 30383302 DOI: 10.1002/jnr.24351] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 10/09/2018] [Accepted: 10/10/2018] [Indexed: 12/30/2022]
Affiliation(s)
- Lyandysha V Zholudeva
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, Pennsylvania.,The Spinal Cord Research Center, College of Medicine, Drexel University, Philadelphia, Pennsylvania
| | - Michael A Lane
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, Pennsylvania.,The Spinal Cord Research Center, College of Medicine, Drexel University, Philadelphia, Pennsylvania
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18
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Zholudeva LV, Iyer N, Qiang L, Spruance VM, Randelman ML, White NW, Bezdudnaya T, Fischer I, Sakiyama-Elbert SE, Lane MA. Transplantation of Neural Progenitors and V2a Interneurons after Spinal Cord Injury. J Neurotrauma 2018; 35:2883-2903. [PMID: 29873284 DOI: 10.1089/neu.2017.5439] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
There is growing interest in the use of neural precursor cells to treat spinal cord injury (SCI). Despite extensive pre-clinical research, it remains unclear as to which donor neuron phenotypes are available for transplantation, whether the same populations exist across different sources of donor tissue (e.g., developing tissue vs. cultured cells), and whether donor cells retain their phenotype once transplanted into the hostile internal milieu of the injured adult spinal cord. In addition, while functional improvements have been reported after neural precursor transplantation post-SCI, the extent of recovery is limited and variable. The present work begins to address these issues by harnessing ventrally derived excitatory pre-motor V2a spinal interneurons (SpINs) to repair the phrenic motor circuit after cervical SCI. Recent studies have demonstrated that Chx10-positive V2a SpINs contribute to anatomical plasticity within the phrenic circuitry after cervical SCI, thus identifying them as a therapeutic candidate. Building upon this discovery, the present work tests the hypothesis that transplantation of neural progenitor cells (NPCs) enriched with V2a INs can contribute to neural networks that promote repair and enhance respiratory plasticity after cervical SCI. Cultured NPCs (neuronal and glial restricted progenitor cells) isolated from E13.5 Green fluorescent protein rats were aggregated with TdTomato-mouse embryonic stem cell-derived V2a INs in vitro, then transplanted into the injured cervical (C3-4) spinal cord. Donor cells survive, differentiate and integrate with the host spinal cord. Functional diaphragm electromyography indicated recovery 1 month following treatment in transplant recipients. Animals that received donor cells enriched with V2a INs showed significantly greater functional improvement than animals that received NPCs alone. The results from this study offer insight into the neuronal phenotypes that might be effective for (re)establishing neuronal circuits in the injured adult central nervous system.
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Affiliation(s)
- Lyandysha V Zholudeva
- 1 Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, Pennsylvania.,2 Spinal Cord Research Center, College of Medicine, Drexel University, Philadelphia, Pennsylvania
| | - Nisha Iyer
- 3 Wisconsin Institute for Discovery, University of Wisconsin, Madison, Wisconsin
| | - Liang Qiang
- 1 Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, Pennsylvania.,2 Spinal Cord Research Center, College of Medicine, Drexel University, Philadelphia, Pennsylvania
| | - Victoria M Spruance
- 1 Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, Pennsylvania.,2 Spinal Cord Research Center, College of Medicine, Drexel University, Philadelphia, Pennsylvania
| | - Margo L Randelman
- 1 Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, Pennsylvania.,2 Spinal Cord Research Center, College of Medicine, Drexel University, Philadelphia, Pennsylvania
| | - Nicholas W White
- 4 Department of Biomedical Engineering, University of Texas, Austin, Texas
| | - Tatiana Bezdudnaya
- 1 Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, Pennsylvania.,2 Spinal Cord Research Center, College of Medicine, Drexel University, Philadelphia, Pennsylvania
| | - Itzhak Fischer
- 1 Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, Pennsylvania.,2 Spinal Cord Research Center, College of Medicine, Drexel University, Philadelphia, Pennsylvania
| | | | - Michael A Lane
- 1 Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, Pennsylvania.,2 Spinal Cord Research Center, College of Medicine, Drexel University, Philadelphia, Pennsylvania
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19
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Spruance VM, Zholudeva LV, Hormigo KM, Randelman ML, Bezdudnaya T, Marchenko V, Lane MA. Integration of Transplanted Neural Precursors with the Injured Cervical Spinal Cord. J Neurotrauma 2018; 35:1781-1799. [PMID: 29295654 PMCID: PMC6033309 DOI: 10.1089/neu.2017.5451] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Cervical spinal cord injuries (SCI) result in devastating functional consequences, including respiratory dysfunction. This is largely attributed to the disruption of phrenic pathways, which control the diaphragm. Recent work has identified spinal interneurons as possible contributors to respiratory neuroplasticity. The present work investigated whether transplantation of developing spinal cord tissue, inherently rich in interneuronal progenitors, could provide a population of new neurons and growth-permissive substrate to facilitate plasticity and formation of novel relay circuits to restore input to the partially denervated phrenic motor circuit. One week after a lateralized, C3/4 contusion injury, adult Sprague-Dawley rats received allografts of dissociated, developing spinal cord tissue (from rats at gestational days 13-14). Neuroanatomical tracing and terminal electrophysiology was performed on the graft recipients 1 month later. Experiments using pseudorabies virus (a retrograde, transynaptic tracer) revealed connections from donor neurons onto host phrenic circuitry and from host, cervical interneurons onto donor neurons. Anatomical characterization of donor neurons revealed phenotypic heterogeneity, though donor-host connectivity appeared selective. Despite the consistent presence of cholinergic interneurons within donor tissue, transneuronal tracing revealed minimal connectivity with host phrenic circuitry. Phrenic nerve recordings revealed changes in burst amplitude after application of a glutamatergic, but not serotonergic antagonist to the transplant, suggesting a degree of functional connectivity between donor neurons and host phrenic circuitry that is regulated by glutamatergic input. Importantly, however, anatomical and functional results were variable across animals, and future studies will explore ways to refine donor cell populations and entrain consistent connectivity.
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Affiliation(s)
- Victoria M Spruance
- Department of Neurobiology and Anatomy, Spinal Cord Research Center, Drexel University College of Medicine , Philadelphia, Pennsylvania
| | - Lyandysha V Zholudeva
- Department of Neurobiology and Anatomy, Spinal Cord Research Center, Drexel University College of Medicine , Philadelphia, Pennsylvania
| | - Kristiina M Hormigo
- Department of Neurobiology and Anatomy, Spinal Cord Research Center, Drexel University College of Medicine , Philadelphia, Pennsylvania
| | - Margo L Randelman
- Department of Neurobiology and Anatomy, Spinal Cord Research Center, Drexel University College of Medicine , Philadelphia, Pennsylvania
| | - Tatiana Bezdudnaya
- Department of Neurobiology and Anatomy, Spinal Cord Research Center, Drexel University College of Medicine , Philadelphia, Pennsylvania
| | - Vitaliy Marchenko
- Department of Neurobiology and Anatomy, Spinal Cord Research Center, Drexel University College of Medicine , Philadelphia, Pennsylvania
| | - Michael A Lane
- Department of Neurobiology and Anatomy, Spinal Cord Research Center, Drexel University College of Medicine , Philadelphia, Pennsylvania
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20
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The Neuroplastic and Therapeutic Potential of Spinal Interneurons in the Injured Spinal Cord. Trends Neurosci 2018; 41:625-639. [PMID: 30017476 DOI: 10.1016/j.tins.2018.06.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 06/06/2018] [Accepted: 06/12/2018] [Indexed: 12/25/2022]
Abstract
The central nervous system is not a static, hard-wired organ. Examples of neuroplasticity, whether at the level of the synapse, the cell, or within and between circuits, can be found during development, throughout the progression of disease, or after injury. One essential component of the molecular, anatomical, and functional changes associated with neuroplasticity is the spinal interneuron (SpIN). Here, we draw on recent multidisciplinary studies to identify and interrogate subsets of SpINs and their roles in locomotor and respiratory circuits. We highlight some of the recent progress that elucidates the importance of SpINs in circuits affected by spinal cord injury (SCI), especially those within respiratory networks; we also discuss potential ways that spinal neuroplasticity can be therapeutically harnessed for recovery.
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21
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Lin CC, Lai SR, Shao YH, Chen CL, Lee KZ. The Therapeutic Effectiveness of Delayed Fetal Spinal Cord Tissue Transplantation on Respiratory Function Following Mid-Cervical Spinal Cord Injury. Neurotherapeutics 2017; 14:792-809. [PMID: 28097486 PMCID: PMC5509620 DOI: 10.1007/s13311-016-0509-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Respiratory impairment due to damage of the spinal respiratory motoneurons and interruption of the descending drives from brainstem premotor neurons to spinal respiratory motoneurons is the leading cause of morbidity and mortality following cervical spinal cord injury. The present study was designed to evaluate the therapeutic effectiveness of delayed transplantation of fetal spinal cord (FSC) tissue on respiratory function in rats with mid-cervical spinal cord injury. Embryonic day-14 rat FSC tissue was transplanted into a C4 spinal cord hemilesion cavity in adult male rats at 1 week postinjury. The histological results showed that FSC-derived grafts can survive, fill the lesion cavity, and differentiate into neurons and astrocytes at 8 weeks post-transplantation. Some FSC-derived graft neurons exhibited specific neurochemical markers of neurotransmitter (e.g., serotonin, noradrenalin, or acetylcholine). Moreover, a robust expression of glutamatergic and γ-aminobutyric acid-ergic fibers was observed within FSC-derived grafts. Retrograde tracing results indicated that there was a connection between FSC-derived grafts and host phrenic nucleus. Neurophysiological recording of the phrenic nerve demonstrated that phrenic burst amplitude ipsilateral to the lesion was significantly greater in injured animals that received FSC transplantation than in those that received buffer transplantation under high respiratory drives. These results suggest that delayed FSC transplantation may have the potential to repair the injured spinal cord and promote respiratory functional recovery after mid-cervical spinal cord injury.
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Affiliation(s)
- Chia-Ching Lin
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Sih-Rong Lai
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Yu-Han Shao
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Chun-Lin Chen
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan
- Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University and Academia Sinica, Kaohsiung, Taiwan
| | - Kun-Ze Lee
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan.
- Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University and Academia Sinica, Kaohsiung, Taiwan.
- Center for Neuroscience, National Sun Yat-sen University, Kaohsiung, Taiwan.
- Institute of Medical Science and Technology, National Sun Yat-sen University, Kaohsiung, Taiwan.
- Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung, Taiwan.
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22
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Xu B, Zhao Y, Xiao Z, Wang B, Liang H, Li X, Fang Y, Han S, Li X, Fan C, Dai J. A Dual Functional Scaffold Tethered with EGFR Antibody Promotes Neural Stem Cell Retention and Neuronal Differentiation for Spinal Cord Injury Repair. Adv Healthc Mater 2017; 6. [PMID: 28233428 DOI: 10.1002/adhm.201601279] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 01/24/2017] [Indexed: 12/22/2022]
Abstract
Neural stem cells (NSCs) transplantation is a promising strategy to restore neuronal relays and neurological function of injured spinal cord because of the differentiation potential into functional neurons, but the transplanted NSCs often largely diffuse from the transplanted site and mainly differentiate into glial cells rather than neurons due to the adverse microenviornment after spinal cord injury (SCI). This paper fabricates a dual functional collagen scaffold tethered with a collagen-binding epidermal growth factor receptor (EGFR) antibody to simultaneously promote NSCs retention and neuronal differentiation by specifically binding to EGFR molecule expressed on NSCs and attenuating EGFR signaling, which is responsible for the inhibition of differentiation of NSCs toward neurons. Compared to unmodified control scaffold, the dual functional scaffold promotes the adhesion and neuronal differentiation of NSCs in vitro. Moreover, the implantation of the dual functional scaffold with exogenous NSCs in rat SCI model can capture and retain NSCs at the injury sites, and promote the neuronal differentiation of the retained NSCs into functional neurons, and finally dedicate to improving motor function of SCI rats, which provides a potential strategy for synchronously promoting stem cell retention and differentiation with biomaterials for SCI repair.
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Affiliation(s)
- Bai Xu
- Key Laboratory for Nano-Bio Interface Research; Division of Nanobiomedicine; Suzhou Institute of Nano-Tech and Nano-Bionics; Chinese Academy of Sciences; Suzhou 215123 P. R. China
| | - Yannan Zhao
- Center for Regenerative Medicine; State Key Laboratory of Molecular Developmental Biology; Institute of Genetics and Developmental Biology; Chinese Academy of Sciences; Beijing 100101 P. R. China
| | - Zhifeng Xiao
- Center for Regenerative Medicine; State Key Laboratory of Molecular Developmental Biology; Institute of Genetics and Developmental Biology; Chinese Academy of Sciences; Beijing 100101 P. R. China
| | - Bin Wang
- Center for Regenerative Medicine; State Key Laboratory of Molecular Developmental Biology; Institute of Genetics and Developmental Biology; Chinese Academy of Sciences; Beijing 100101 P. R. China
| | - Hui Liang
- Key Laboratory for Nano-Bio Interface Research; Division of Nanobiomedicine; Suzhou Institute of Nano-Tech and Nano-Bionics; Chinese Academy of Sciences; Suzhou 215123 P. R. China
| | - Xing Li
- Key Laboratory for Nano-Bio Interface Research; Division of Nanobiomedicine; Suzhou Institute of Nano-Tech and Nano-Bionics; Chinese Academy of Sciences; Suzhou 215123 P. R. China
- Center for Regenerative Medicine; State Key Laboratory of Molecular Developmental Biology; Institute of Genetics and Developmental Biology; Chinese Academy of Sciences; Beijing 100101 P. R. China
| | - Yongxiang Fang
- Center for Regenerative Medicine; State Key Laboratory of Molecular Developmental Biology; Institute of Genetics and Developmental Biology; Chinese Academy of Sciences; Beijing 100101 P. R. China
| | - Sufang Han
- Center for Regenerative Medicine; State Key Laboratory of Molecular Developmental Biology; Institute of Genetics and Developmental Biology; Chinese Academy of Sciences; Beijing 100101 P. R. China
| | - Xiaoran Li
- Key Laboratory for Nano-Bio Interface Research; Division of Nanobiomedicine; Suzhou Institute of Nano-Tech and Nano-Bionics; Chinese Academy of Sciences; Suzhou 215123 P. R. China
| | - Caixia Fan
- Key Laboratory for Nano-Bio Interface Research; Division of Nanobiomedicine; Suzhou Institute of Nano-Tech and Nano-Bionics; Chinese Academy of Sciences; Suzhou 215123 P. R. China
| | - Jianwu Dai
- Key Laboratory for Nano-Bio Interface Research; Division of Nanobiomedicine; Suzhou Institute of Nano-Tech and Nano-Bionics; Chinese Academy of Sciences; Suzhou 215123 P. R. China
- Center for Regenerative Medicine; State Key Laboratory of Molecular Developmental Biology; Institute of Genetics and Developmental Biology; Chinese Academy of Sciences; Beijing 100101 P. R. China
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23
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Dunnett SB, Björklund A. Mechanisms and use of neural transplants for brain repair. PROGRESS IN BRAIN RESEARCH 2017; 230:1-51. [PMID: 28552225 DOI: 10.1016/bs.pbr.2016.11.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Under appropriate conditions, neural tissues transplanted into the adult mammalian brain can survive, integrate, and function so as to influence the behavior of the host, opening the prospect of repairing neuronal damage, and alleviating symptoms associated with neuronal injury or neurodegenerative disease. Alternative mechanisms of action have been postulated: nonspecific effects of surgery; neurotrophic and neuroprotective influences on disease progression and host plasticity; diffuse or locally regulated pharmacological delivery of deficient neurochemicals, neurotransmitters, or neurohormones; restitution of the neuronal and glial environment necessary for proper host neuronal support and processing; promoting local and long-distance host and graft axon growth; formation of reciprocal connections and reconstruction of local circuits within the host brain; and up to full integration and reconstruction of fully functional host neuronal networks. Analysis of neural transplants in a broad range of anatomical systems and disease models, on simple and complex classes of behavioral function and information processing, have indicated that all of these alternative mechanisms are likely to contribute in different circumstances. Thus, there is not a single or typical mode of graft function; rather grafts can and do function in multiple ways, specific to each particular context. Consequently, to develop an effective cell-based therapy, multiple dimensions must be considered: the target disease pathogenesis; the neurodegenerative basis of each type of physiological dysfunction or behavioral symptom; the nature of the repair required to alleviate or remediate the functional impairments of particular clinical relevance; and identification of a suitable cell source or delivery system, along with the site and method of implantation, that can achieve the sought for repair and recovery.
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24
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Abstract
Stem cells, especially neural stem cells (NSCs), are a very attractive cell source for potential reconstruction of injured spinal cord though either neuroprotection, neural regeneration, remyelination, replacement of lost neural cells, or reconnection of disrupted axons. The later have great potential since recent studies demonstrate long-distance growth and connectivity of axons derived from transplanted NSCs after spinal cord injury (SCI). In addition, transplanted NSCs constitute a permissive environment for host axonal regeneration and serve as new targets for host axonal connection. This reciprocal connection between grafted neurons and host neurons constitutes a neuronal relay formation that could restore functional connectivity after SCI.
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25
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Sandhu MS, Ross HH, Lee KZ, Ormerod BK, Reier PJ, Fuller DD. Intraspinal transplantation of subventricular zone-derived neural progenitor cells improves phrenic motor output after high cervical spinal cord injury. Exp Neurol 2017; 287:205-215. [PMID: 27302679 PMCID: PMC6154390 DOI: 10.1016/j.expneurol.2016.06.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Revised: 06/06/2016] [Accepted: 06/09/2016] [Indexed: 01/30/2023]
Abstract
Following spinal cord injury (SCI), intraspinal transplantation of neural progenitor cells (NPCs) harvested from the forebrain sub-ventricular zone (SVZ) can improve locomotor outcomes. Cervical SCI often results in respiratory-related impairments, and here we used an established model cervical SCI (C2 hemisection, C2Hx) to confirm the feasibility of mid-cervical transplantation of SVZ-derived NPCs and the hypothesis that that this procedure would improve spontaneous respiratory motor recovery. NPCs were isolated from the SVZ of enhanced green fluorescent protein (GFP) expressing neonatal rats, and then intraspinally delivered immediately caudal to an acute C2Hx lesion in adult non-GFP rats. Whole body plethysmography conducted at 4 and 8wks post-transplant demonstrated increased inspiratory tidal volume in SVZ vs. sham transplants during hypoxic (P=0.003) or hypercapnic respiratory challenge (P=0.019). Phrenic nerve output was assessed at 8wks post-transplant; burst amplitude recorded ipsilateral to C2Hx was greater in SVZ vs. sham rats across a wide range of conditions (e.g., quiet breathing through maximal chemoreceptor stimulation; P<0.001). Stereological analyses at 8wks post-injury indicated survival of ~50% of transplanted NPCs with ~90% of cells distributed in ipsilateral white matter at or near the injection site. Peak inspiratory phrenic bursting after NPC transplant was positively correlated with the total number of surviving cells (P<0.001). Immunohistochemistry confirmed an astrocytic phenotype in a subset of the transplanted cells with no evidence for neuronal differentiation. We conclude that intraspinal transplantation of SVZ-derived NPCs can improve respiratory recovery following high cervical SCI.
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Affiliation(s)
- M S Sandhu
- University of Florida, Department of Physical Therapy, P.O. Box 100154, Gainesville, FL 32610-0154, United States
| | - H H Ross
- University of Florida, Department of Physical Therapy, P.O. Box 100154, Gainesville, FL 32610-0154, United States
| | - K Z Lee
- University of Florida, Department of Physical Therapy, P.O. Box 100154, Gainesville, FL 32610-0154, United States
| | - B K Ormerod
- University of Florida, Department of Biomedical Engineering, P.O. Box 116131, Gainesville, FL 32611-6131, United States
| | - P J Reier
- University of Florida, Department of Neuroscience, P.O. Box 100244, Gainesville, FL 32610-0244, United States
| | - D D Fuller
- University of Florida, Department of Physical Therapy, P.O. Box 100154, Gainesville, FL 32610-0154, United States.
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26
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Lane MA, Lepore AC, Fischer I. Improving the therapeutic efficacy of neural progenitor cell transplantation following spinal cord injury. Expert Rev Neurother 2016; 17:433-440. [PMID: 27927055 DOI: 10.1080/14737175.2017.1270206] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
INTRODUCTION There have been a wide range of preclinical studies testing cellular therapies to repair the injured spinal cord, yet they remain a challenge to translate because of inconsistencies in efficacy, limited number of patients with acute/subacute SCI and the high costs of clinical trials. Area covered: This paper focusses on the therapeutic potential of neural precursor cells (NPCs) because they can provide the cellular components capable of promoting repair and enhancing functional improvement following spinal cord injury (SCI). The authors discuss the challenges of NPC transplantation with respect to different populations of NPCs of glial and neuronal lineages, the timing of treatment relative to acute and chronic injury, and the progress in ongoing clinical trials. Expert commentary: Preclinical research will continue to elucidate mechanisms of recovery associated with NPC transplants, including increasing the partnership with related fields such as spinal atrophies and multiple sclerosis. The clinical trials landscape will grow and include both acute and chronic SCI with increased partnership and strengthened communication between biotechnology, government and academia. There will also be growing effort to develop better biomarkers, imaging and outcome measures for detailed assessment of neurological function and measures of quality of life.
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Affiliation(s)
- Michael A Lane
- a Department of Neurobiology & Anatomy, Spinal Cord Research Center , Drexel University , Philadelphia , PA , USA
| | - Angelo C Lepore
- b Department of Neuroscience, Vickie and Jack Farber Institute for Neuroscience , Sidney Kimmel Medical College at Thomas Jefferson University , Philadelphia , PA , USA
| | - Itzhak Fischer
- a Department of Neurobiology & Anatomy, Spinal Cord Research Center , Drexel University , Philadelphia , PA , USA
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27
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Charsar BA, Urban MW, Lepore AC. Harnessing the power of cell transplantation to target respiratory dysfunction following spinal cord injury. Exp Neurol 2016; 287:268-275. [PMID: 27531634 DOI: 10.1016/j.expneurol.2016.08.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 07/29/2016] [Accepted: 08/12/2016] [Indexed: 12/13/2022]
Abstract
The therapeutic benefit of cell transplantation has been assessed in a host of central nervous system (CNS) diseases, including disorders of the spinal cord such as traumatic spinal cord injury (SCI). The promise of cell transplantation to preserve and/or restore normal function can be aimed at a variety of therapeutic mechanisms, including replacement of lost or damaged CNS cell types, promotion of axonal regeneration or sprouting, neuroprotection, immune response modulation, and delivery of gene products such as neurotrophic factors, amongst other possibilities. Despite significant work in the field of transplantation in models of SCI, limited attention has been directed at harnessing the therapeutic potential of cell grafting for preserving respiratory function after SCI, despite the critical role pulmonary compromise plays in patient outcome in this devastating disease. Here, we will review the limited number of studies that have demonstrated the therapeutic potential of intraspinal transplantation of a variety of cell types for addressing respiratory dysfunction in SCI.
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Affiliation(s)
- Brittany A Charsar
- Department of Neuroscience, Farber Institute for Neurosciences, Sidney Kimmel Medical College, Thomas Jefferson University, 900 Walnut Street, JHN 418, Philadelphia, PA, 19107, United States
| | - Mark W Urban
- Department of Neuroscience, Farber Institute for Neurosciences, Sidney Kimmel Medical College, Thomas Jefferson University, 900 Walnut Street, JHN 418, Philadelphia, PA, 19107, United States
| | - Angelo C Lepore
- Department of Neuroscience, Farber Institute for Neurosciences, Sidney Kimmel Medical College, Thomas Jefferson University, 900 Walnut Street, JHN 418, Philadelphia, PA, 19107, United States.
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28
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Nichols NL, Mitchell GS. Quantitative assessment of integrated phrenic nerve activity. Respir Physiol Neurobiol 2015; 226:81-6. [PMID: 26724605 DOI: 10.1016/j.resp.2015.12.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 12/07/2015] [Accepted: 12/14/2015] [Indexed: 12/30/2022]
Abstract
Integrated electrical activity in the phrenic nerve is commonly used to assess within-animal changes in phrenic motor output. Because of concerns regarding the consistency of nerve recordings, activity is most often expressed as a percent change from baseline values. However, absolute values of nerve activity are necessary to assess the impact of neural injury or disease on phrenic motor output. To date, no systematic evaluations of the repeatability/reliability have been made among animals when phrenic recordings are performed by an experienced investigator using standardized methods. We performed a meta-analysis of studies reporting integrated phrenic nerve activity in many rat groups by the same experienced investigator; comparisons were made during baseline and maximal chemoreceptor stimulation in 14 wild-type Harlan and 14 Taconic Sprague Dawley groups, and in 3 pre-symptomatic and 11 end-stage SOD1(G93A) Taconic rat groups (an ALS model). Meta-analysis results indicate: (1) consistent measurements of integrated phrenic activity in each sub-strain of wild-type rats; (2) with bilateral nerve recordings, left-to-right integrated phrenic activity ratios are ∼1.0; and (3) consistently reduced activity in end-stage SOD1(G93A) rats. Thus, with appropriate precautions, integrated phrenic nerve activity enables robust, quantitative comparisons among nerves or experimental groups, including differences caused by neuromuscular disease.
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Affiliation(s)
- Nicole L Nichols
- Department of Comparative Biosciences, University of Wisconsin, Madison, WI 53706, United States; Department of Biomedical Sciences, University of Missouri, Columbia, MO 65211, United States.
| | - Gordon S Mitchell
- Department of Comparative Biosciences, University of Wisconsin, Madison, WI 53706, United States; Department of Physical Therapy, McKnight Brain Institute and Center for Respiratory Research and Rehabilitation, University of Florida, Gainesville, FL 32611-0154, United States
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Abstract
Spinal cord injury (SCI) results not only in motor and sensory deficits but also in autonomic dysfunctions. The disruption of connections between higher brain centers and the spinal cord, or the impaired autonomic nervous system itself, manifests a broad range of autonomic abnormalities. This includes compromised cardiovascular, respiratory, urinary, gastrointestinal, thermoregulatory, and sexual activities. These disabilities evoke potentially life-threatening symptoms that severely interfere with the daily living of those with SCI. In particular, high thoracic or cervical SCI often causes disordered hemodynamics due to deregulated sympathetic outflow. Episodic hypertension associated with autonomic dysreflexia develops as a result of massive sympathetic discharge often triggered by unpleasant visceral or sensory stimuli below the injury level. In the pelvic floor, bladder and urethral dysfunctions are classified according to upper motor neuron versus lower motor neuron injuries; this is dependent on the level of lesion. Most impairments of the lower urinary tract manifest in two interrelated complications: bladder storage and emptying. Inadequate or excessive detrusor and sphincter functions as well as detrusor-sphincter dyssynergia are examples of micturition abnormalities stemming from SCI. Gastrointestinal motility disorders in spinal cord injured-individuals are comprised of gastric dilation, delayed gastric emptying, and diminished propulsive transit along the entire gastrointestinal tract. As a critical consequence of SCI, neurogenic bowel dysfunction exhibits constipation and/or incontinence. Thus, it is essential to recognize neural mechanisms and pathophysiology underlying various complications of autonomic dysfunctions after SCI. This overview provides both vital information for better understanding these disorders and guides to pursue novel therapeutic approaches to alleviate secondary complications.
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Affiliation(s)
- Shaoping Hou
- Spinal Cord Research Center, Department of Neurobiology & Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania
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Gonzalez-Rothi EJ, Lee KZ, Dale EA, Reier PJ, Mitchell GS, Fuller DD. Intermittent hypoxia and neurorehabilitation. J Appl Physiol (1985) 2015; 119:1455-65. [PMID: 25997947 DOI: 10.1152/japplphysiol.00235.2015] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 05/18/2015] [Indexed: 02/05/2023] Open
Abstract
In recent years, it has become clear that brief, repeated presentations of hypoxia [i.e., acute intermittent hypoxia (AIH)] can boost the efficacy of more traditional therapeutic strategies in certain cases of neurologic dysfunction. This hypothesis derives from a series of studies in animal models and human subjects performed over the past 35 yr. In 1980, Millhorn et al. (Millhorn DE, Eldridge FL, Waldrop TG. Respir Physiol 41: 87-103, 1980) showed that electrical stimulation of carotid chemoafferent neurons produced a persistent, serotonin-dependent increase in phrenic motor output that outlasts the stimulus for more than 90 min (i.e., a "respiratory memory"). AIH elicits similar phrenic "long-term facilitation" (LTF) by a mechanism that requires cervical spinal serotonin receptor activation and de novo protein synthesis. From 2003 to present, a series of studies demonstrated that AIH can induce neuroplasticity in the injured spinal cord, causing functional recovery of breathing capacity after cervical spinal injury. Subsequently, it was demonstrated that repeated AIH (rAIH) can induce recovery of limb function, and the functional benefits of rAIH are greatest when paired with task-specific training. Since uncontrolled and/or prolonged intermittent hypoxia can elicit pathophysiology, a challenge of intermittent hypoxia research is to ensure that therapeutic protocols are well below the threshold for pathogenesis. This is possible since many low dose rAIH protocols have induced functional benefits without evidence of pathology. We propose that carefully controlled rAIH is a safe and noninvasive modality that can be paired with other neurorehabilitative strategies including traditional activity-based physical therapy or cell-based therapies such as intraspinal transplantation of neural progenitors.
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Affiliation(s)
- Elisa J Gonzalez-Rothi
- Department of Physical Therapy College of Public Health and Health Professions, University of Florida, Gainesville, Florida
| | - Kun-Ze Lee
- Department of Biological Sciences, College of Science, National Sun Yat-sen University, Kaohsiung City, Taiwan
| | - Erica A Dale
- Department of Integrative Biology and Physiology, University of California-Los Angeles, Los Angeles, California; and
| | - Paul J Reier
- Department of Neuroscience, College of Medicine, University of Florida, Gainesville, Florida
| | - Gordon S Mitchell
- Department of Physical Therapy College of Public Health and Health Professions, University of Florida, Gainesville, Florida
| | - David D Fuller
- Department of Physical Therapy College of Public Health and Health Professions, University of Florida, Gainesville, Florida;
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31
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Bonner JF, Steward O. Repair of spinal cord injury with neuronal relays: From fetal grafts to neural stem cells. Brain Res 2015; 1619:115-23. [PMID: 25591483 DOI: 10.1016/j.brainres.2015.01.006] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 12/29/2014] [Accepted: 01/05/2015] [Indexed: 02/01/2023]
Abstract
Spinal cord injury (SCI) disrupts the long axonal tracts of the spinal cord leading to devastating loss of function. Cell transplantation in the injured spinal cord has the potential to lead to recovery after SCI via a variety of mechanisms. One such strategy is the formation of neuronal relays between injured long tract axons and denervated neurons. The idea of creating a neuronal relay was first proposed over 25 years ago when fetal tissue was first successfully transplanted into the injured rodent spinal cord. Advances in labeling of grafted cells and the development of neural stem cell culturing techniques have improved the ability to create and refine such relays. Several recent studies have examined the ability to create a novel neuronal circuit between injured axons and denervated targets. This approach is an alternative to long-distance regeneration of damaged axons that may provide a meaningful degree of recovery without direct recreation of lost pathways. This brief review will examine the contribution of fetal grafting to current advances in neuronal grafting. Of particular interest will be the ability of transplanted neurons derived from fetal grafts, neural precursor cells and neural stem cells to reconnect long distance motor and sensory pathways of the injured spinal cord. This article is part of a Special Issue entitled SI: Spinal cord injury.
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Affiliation(s)
- Joseph F Bonner
- Reeve-Irvine Research Center, University of California, 1105 Gillespie Neuroscience Research Facility, Irvine, CA 92697-4265, USA.
| | - Oswald Steward
- Reeve-Irvine Research Center, University of California, 1105 Gillespie Neuroscience Research Facility, Irvine, CA 92697-4265, USA; Departments of Anatomy & Neurobiology, Neurobiology & Behavior, and Neurosurgery, University of California at Irvine School of Medicine, Irvine, CA 92697-4265, USA
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32
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Dulin JN, Lu P. Bridging the injured spinal cord with neural stem cells. Neural Regen Res 2014; 9:229-31. [PMID: 25206804 PMCID: PMC4146155 DOI: 10.4103/1673-5374.128212] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2014] [Indexed: 12/19/2022] Open
Affiliation(s)
- Jennifer N Dulin
- Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Paul Lu
- Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA ; Veterans Administration Medical Center, San Diego, CA, 92161, USA
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33
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Lu P, Kadoya K, Tuszynski MH. Axonal growth and connectivity from neural stem cell grafts in models of spinal cord injury. Curr Opin Neurobiol 2014; 27:103-9. [DOI: 10.1016/j.conb.2014.03.010] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 03/12/2014] [Accepted: 03/14/2014] [Indexed: 02/06/2023]
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Liu Y, Grumbles RM, Thomas CK. Electrical stimulation of transplanted motoneurons improves motor unit formation. J Neurophysiol 2014; 112:660-70. [PMID: 24848463 DOI: 10.1152/jn.00806.2013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Motoneurons die following spinal cord trauma and with neurological disease. Intact axons reinnervate nearby muscle fibers to compensate for the death of motoneurons, but when an entire motoneuron pool dies, there is complete denervation. To reduce denervation atrophy, we have reinnervated muscles in Fisher rats from local transplants of embryonic motoneurons in peripheral nerve. Since growth of axons from embryonic neurons is activity dependent, our aim was to test whether brief electrical stimulation of the neurons immediately after transplantation altered motor unit numbers and muscle properties 10 wk later. All surgical procedures and recordings were done in anesthetized animals. The muscle consequences of motoneuron death were mimicked by unilateral sciatic nerve section. One week later, 200,000 embryonic day 14 and 15 ventral spinal cord cells, purified for motoneurons, were injected into the tibial nerve 10-15 mm from the gastrocnemii muscles as the only neuron source for muscle reinnervation. The cells were stimulated immediately after transplantation for up to 1 h using protocols designed to examine differential effects due to pulse number, stimulation frequency, pattern, and duration. Electrical stimulation that included short rests and lasted for 1 h resulted in higher motor unit counts. Muscles with higher motor unit counts had more reinnervated fibers and were stronger. Denervated muscles had to be stimulated directly to evoke contractions. These results show that brief electrical stimulation of embryonic neurons, in vivo, has long-term effects on motor unit formation and muscle force. This muscle reinnervation provides the opportunity to use patterned electrical stimulation to produce functional movements.
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Affiliation(s)
- Yang Liu
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, Florida; and
| | - Robert M Grumbles
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, Florida; and
| | - Christine K Thomas
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, Florida; and Department of Neurological Surgery, Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, Florida
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35
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Nicaise C, Frank DM, Hala TJ, Authelet M, Pochet R, Adriaens D, Brion JP, Wright MC, Lepore AC. Early phrenic motor neuron loss and transient respiratory abnormalities after unilateral cervical spinal cord contusion. J Neurotrauma 2014; 30:1092-9. [PMID: 23534670 DOI: 10.1089/neu.2012.2728] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Contusion-type cervical spinal cord injury (SCI) is one of the most common forms of SCI observed in patients. In particular, injuries targeting the C3-C5 region affect the pool of phrenic motor neurons (PhMNs) that innervates the diaphragm, resulting in significant and often chronic respiratory dysfunction. Using a previously described rat model of unilateral midcervical C4 contusion with the Infinite Horizon Impactor, we have characterized the early time course of PhMN degeneration and consequent respiratory deficits following injury, as this knowledge is important for designing relevant treatment strategies targeting protection and plasticity of PhMN circuitry. PhMN loss (48% of the ipsilateral pool) occurred almost entirely during the first 24 h post-injury, resulting in persistent phrenic nerve axonal degeneration and denervation at the diaphragm neuromuscular junction (NMJ). Reduced diaphragm compound muscle action potential amplitudes following phrenic nerve stimulation were observed as early as the first day post-injury (30% of pre-injury maximum amplitude), with slow functional improvement over time that was associated with partial reinnervation at the diaphragm NMJ. Consistent with ipsilateral diaphragmatic compromise, the injury resulted in rapid, yet only transient, changes in overall ventilatory parameters measured via whole-body plethysmography, including increased respiratory rate, decreased tidal volume, and decreased peak inspiratory flow. Despite significant ipsilateral PhMN loss, the respiratory system has the capacity to quickly compensate for partially impaired hemidiaphragm function, suggesting that C4 hemicontusion in rats is a model of SCI that manifests subacute respiratory abnormalities. Collectively, these findings demonstrate significant and persistent diaphragm compromise in a clinically relevant model of midcervical contusion SCI; however, the therapeutic window for PhMN protection is restricted to early time points post-injury. On the contrary, preventing loss of innervation by PhMNs and/or inducing plasticity in spared PhMN axons at the diaphragm NMJ are relevant long-term targets.
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Affiliation(s)
- Charles Nicaise
- Department of Neuroscience, Farber Institute for Neurosciences, Thomas Jefferson University Medical College, Philadelphia, PA 19107, USA
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36
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Warren PM, Alilain WJ. The challenges of respiratory motor system recovery following cervical spinal cord injury. PROGRESS IN BRAIN RESEARCH 2014; 212:173-220. [DOI: 10.1016/b978-0-444-63488-7.00010-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Lee KZ, Lane MA, Dougherty BJ, Mercier LM, Sandhu MS, Sanchez JC, Reier PJ, Fuller DD. Intraspinal transplantation and modulation of donor neuron electrophysiological activity. Exp Neurol 2013; 251:47-57. [PMID: 24192152 DOI: 10.1016/j.expneurol.2013.10.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 10/21/2013] [Accepted: 10/26/2013] [Indexed: 10/26/2022]
Abstract
Rat fetal spinal cord (FSC) tissue, naturally enriched with interneuronal progenitors, was introduced into high cervical, hemi-resection (Hx) lesions. Electrophysiological analyses were conducted to determine if such grafts exhibit physiologically-patterned neuronal activity and if stimuli which increase respiratory motor output also alter donor neuron bursting. Three months following transplantation, the bursting activity of FSC neurons and the contralateral phrenic nerve were recorded in anesthetized rats during a normoxic baseline period and brief respiratory challenges. Spontaneous neuronal activity was detected in 80% of the FSC transplants, and autocorrelation of action potential spikes revealed distinct correlogram peaks in 87% of neurons. At baseline, the average discharge frequency of graft neurons was 13.0 ± 1.7 Hz, and discharge frequency increased during a hypoxic respiratory challenge (p<0.001). Parallel studies in unanesthetized rats showed that FSC tissue recipients had larger inspiratory tidal volumes during brief hypoxic exposures (p<0.05 vs. C2Hx rats). Anatomical connectivity was explored in additional graft recipients by injecting a transsynaptic retrograde viral tracer (pseudorabies virus, PRV) directly into matured transplants. Neuronal labeling occurred throughout graft tissues and also in the host spinal cord and brainstem nuclei, including those associated with respiratory control. These results underscore the neuroplastic potential of host-graft interactions and training approaches to enhance functional integration within targeted spinal circuitry.
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Affiliation(s)
- Kun-Ze Lee
- Dept. Physical Therapy, College of Public Health and Health Professions, McKnight Brain Institute, University of Florida, USA
| | - Michael A Lane
- Dept. of Biomedical Engineering, College of Engineering, University of Miami, USA
| | - Brendan J Dougherty
- Dept. Physical Therapy, College of Public Health and Health Professions, McKnight Brain Institute, University of Florida, USA
| | - Lynne M Mercier
- Dept. Neuroscience, College of Medicine, McKnight Brain Institute, University of Florida, USA
| | - Milapjit S Sandhu
- Dept. Physical Therapy, College of Public Health and Health Professions, McKnight Brain Institute, University of Florida, USA
| | - Justin C Sanchez
- Dept. of Biomedical Engineering, College of Engineering, University of Miami, USA
| | - Paul J Reier
- Dept. Neuroscience, College of Medicine, McKnight Brain Institute, University of Florida, USA
| | - David D Fuller
- Dept. Physical Therapy, College of Public Health and Health Professions, McKnight Brain Institute, University of Florida, USA.
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38
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van Gorp S, Leerink M, Kakinohana O, Platoshyn O, Santucci C, Galik J, Joosten EA, Hruska-Plochan M, Goldberg D, Marsala S, Johe K, Ciacci JD, Marsala M. Amelioration of motor/sensory dysfunction and spasticity in a rat model of acute lumbar spinal cord injury by human neural stem cell transplantation. Stem Cell Res Ther 2013; 4:57. [PMID: 23710605 PMCID: PMC3706882 DOI: 10.1186/scrt209] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 04/25/2013] [Indexed: 12/15/2022] Open
Abstract
Introduction Intraspinal grafting of human neural stem cells represents a promising approach to promote recovery of function after spinal trauma. Such a treatment may serve to: I) provide trophic support to improve survival of host neurons; II) improve the structural integrity of the spinal parenchyma by reducing syringomyelia and scarring in trauma-injured regions; and III) provide neuronal populations to potentially form relays with host axons, segmental interneurons, and/or α-motoneurons. Here we characterized the effect of intraspinal grafting of clinical grade human fetal spinal cord-derived neural stem cells (HSSC) on the recovery of neurological function in a rat model of acute lumbar (L3) compression injury. Methods Three-month-old female Sprague–Dawley rats received L3 spinal compression injury. Three days post-injury, animals were randomized and received intraspinal injections of either HSSC, media-only, or no injections. All animals were immunosuppressed with tacrolimus, mycophenolate mofetil, and methylprednisolone acetate from the day of cell grafting and survived for eight weeks. Motor and sensory dysfunction were periodically assessed using open field locomotion scoring, thermal/tactile pain/escape thresholds and myogenic motor evoked potentials. The presence of spasticity was measured by gastrocnemius muscle resistance and electromyography response during computer-controlled ankle rotation. At the end-point, gait (CatWalk), ladder climbing, and single frame analyses were also assessed. Syrinx size, spinal cord dimensions, and extent of scarring were measured by magnetic resonance imaging. Differentiation and integration of grafted cells in the host tissue were validated with immunofluorescence staining using human-specific antibodies. Results Intraspinal grafting of HSSC led to a progressive and significant improvement in lower extremity paw placement, amelioration of spasticity, and normalization in thermal and tactile pain/escape thresholds at eight weeks post-grafting. No significant differences were detected in other CatWalk parameters, motor evoked potentials, open field locomotor (Basso, Beattie, and Bresnahan locomotion score (BBB)) score or ladder climbing test. Magnetic resonance imaging volume reconstruction and immunofluorescence analysis of grafted cell survival showed near complete injury-cavity-filling by grafted cells and development of putative GABA-ergic synapses between grafted and host neurons. Conclusions Peri-acute intraspinal grafting of HSSC can represent an effective therapy which ameliorates motor and sensory deficits after traumatic spinal cord injury.
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Stein PSG. Molecular, genetic, cellular, and network functions in the spinal cord and brainstem. Ann N Y Acad Sci 2013; 1279:1-12. [PMID: 23530997 DOI: 10.1111/nyas.12083] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Studies of the model systems of spinal cord and brainstem reveal molecular, genetic, and cellular mechanisms that are critical for network and behavioral functions in the nervous system. Recent experiments establish the importance of neurogenetics in revealing cellular and network properties. Breakthroughs that utilize direct visualization of neuronal activity and network structure provide new insights. Major discoveries of plasticity in the spinal cord and brainstem contribute to basic neuroscience and, in addition, have promising therapeutic implications.
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Affiliation(s)
- Paul S G Stein
- Biology Department, Washington University, St. Louis, MO 63130, USA.
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40
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Geissler SA, Schmidt CE, Schallert T. Rodent Models and Behavioral Outcomes of Cervical Spinal Cord Injury. ACTA ACUST UNITED AC 2013; Suppl 4. [PMID: 25309824 PMCID: PMC4191831 DOI: 10.4172/2165-7939.s4-001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Rodent spinal cord injury (SCI) models have been developed to examine functional and physiological deficits after spinal cord injury with the hope that these models will elucidate information about human SCI. Models are needed to examine possible treatments and to understand histopathology after SCI; however, they should be considered carefully and chosen based on the goals of the study being performed. Contusion, compression, transection, and other models exist and have the potential to reveal important information about SCI that may be related to human SCI and the outcomes of treatment and timing of intervention.
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Affiliation(s)
- Sydney A Geissler
- Department of Biomedical Engineering, The University of Texas, Austin, TX, USA
| | - Christine E Schmidt
- Department of Biomedical Engineering, The University of Texas, Austin, TX, USA ; Professor, J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - Timothy Schallert
- Professor, Department of Psychology, The University of Texas, Austin, TX, USA ; Professor, Department of Neuroscience, The University of Texas, Austin, TX, USA
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41
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Bonner JF, Haas CJ, Fischer I. Preparation of neural stem cells and progenitors: neuronal production and grafting applications. Methods Mol Biol 2013; 1078:65-88. [PMID: 23975822 DOI: 10.1007/978-1-62703-640-5_7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Neural stem cells (NSC) are not only a valuable tool for the study of neural development and function, but an integral component in the development of transplantation strategies for neural disease. NSC can be used to study how neurons acquire distinct phenotypes and how the reciprocal interactions between neurons and glia in the developing nervous system shape the structure and function of the central nervous system (CNS). In addition, neurons prepared from NSC can be used to elucidate the molecular basis of neurological disorders as well as potential treatments. Although NSC can be derived from different species and many sources, including embryonic stem cells, induced pluripotent stem cells, adult CNS, and direct reprogramming of non-neural cells, isolating primary NSC directly from rat fetal tissue is the most common technique for preparation and study of neurons with a wealth of data available for comparison. Regardless of the source material, similar techniques are used to maintain NSC in culture and to differentiate NSC toward mature neural lineages. This chapter will describe specific methods for isolating multipotent NSC and neural precursor cells (NPC) from embryonic rat CNS tissue (mostly spinal cord). In particular, NPC can be separated into neuronal and glial restricted precursors (NRP and GRP, respectively) and used to reliably produce neurons or glial cells both in vitro and following transplantation into the adult CNS. This chapter will describe in detail the methods required for the isolation, propagation, storage, and differentiation of NSC and NPC isolated from rat spinal cords for subsequent in vitro or in vivo studies.
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Affiliation(s)
- Joseph F Bonner
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA
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42
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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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43
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Treatments to restore respiratory function after spinal cord injury and their implications for regeneration, plasticity and adaptation. Exp Neurol 2011; 235:18-25. [PMID: 22200541 DOI: 10.1016/j.expneurol.2011.12.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Revised: 11/18/2011] [Accepted: 12/09/2011] [Indexed: 02/04/2023]
Abstract
Spinal cord injury (SCI) often leads to impaired breathing. In most cases, such severe respiratory complications lead to morbidity and death. However, in the last few years there has been extensive work examining ways to restore this vital function after experimental spinal cord injury. In addition to finding strategies to rescue breathing activity, many of these experiments have also yielded a great deal of information about the innate plasticity and capacity for adaptation in the respiratory system and its associated circuitry in the spinal cord. This review article will highlight experimental SCI resulting in compromised breathing, the various methods of restoring function after such injury, and some recent findings from our own laboratory. Additionally, it will discuss findings about motor and CNS respiratory plasticity and adaptation with potential clinical and translational implications.
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Dougherty BJ, Lee KZ, Lane MA, Reier PJ, Fuller DD. Contribution of the spontaneous crossed-phrenic phenomenon to inspiratory tidal volume in spontaneously breathing rats. J Appl Physiol (1985) 2011; 112:96-105. [PMID: 22033536 DOI: 10.1152/japplphysiol.00690.2011] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Spinal cord hemisection at C2 (C2HS) severs bulbospinal inputs to ipsilateral phrenic motoneurons causing transient hemidiaphragm paralysis. The spontaneous crossed-phrenic phenomenon (sCPP) describes the spontaneous recovery of ipsilateral phrenic bursting following C2HS. We reasoned that the immediate (next breath) changes in tidal volume (V(T)) induced by ipsilateral phrenicotomy during spontaneous breathing would provide a quantitative measure of the contribution of the sCPP to postinjury V(T). Using this approach, we tested the hypothesis that the sCPP makes more substantial contributions to V(T) when respiratory drive is increased. Pneumotachography was used to measure V(T) in anesthetized, spontaneously breathing adult male rats at intervals following C2HS. A progressive increase in V(T) (ml/breath) occurred over an 8 wk period following C2HS during both poikilocapnic baseline breathing and hypercapnic respiratory challenge (7% inspired CO(2)). The sCPP did not impact baseline breathing at 1-3 days postinjury since V(T) was unchanged after ipsilateral phrenicotomy. However, by 2 wk post-C2HS, baseline phrenicotomy caused a 16 ± 2% decline in V(T); a comparable 16 ± 4% decline occurred at 8 wk. Contrary to our hypothesis, the phrenicotomy-induced declines in V(T) (%) during hypercapnic respiratory stimulation did not differ from the baseline response at any postinjury time point (all P > 0.11). We conclude that by 2 wk post-C2HS the sCPP makes a meaningful contribution to V(T) that is similar across different levels of respiratory drive.
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Affiliation(s)
- Brendan J Dougherty
- Department of Physical Therapy, McKnight Brain Institute, College of Public Health and Health Professions, University of Florida, Gainesville, Florida, USA
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Grafted human-induced pluripotent stem-cell-derived neurospheres promote motor functional recovery after spinal cord injury in mice. Proc Natl Acad Sci U S A 2011; 108:16825-30. [PMID: 21949375 DOI: 10.1073/pnas.1108077108] [Citation(s) in RCA: 386] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Once their safety is confirmed, human-induced pluripotent stem cells (hiPSCs), which do not entail ethical concerns, may become a preferred cell source for regenerative medicine. Here, we investigated the therapeutic potential of transplanting hiPSC-derived neurospheres (hiPSC-NSs) into nonobese diabetic (NOD)-severe combined immunodeficient (SCID) mice to treat spinal cord injury (SCI). For this, we used a hiPSC clone (201B7), established by transducing four reprogramming factors (Oct3/4, Sox2, Klf4, and c-Myc) into adult human fibroblasts. Grafted hiPSC-NSs survived, migrated, and differentiated into the three major neural lineages (neurons, astrocytes, and oligodendrocytes) within the injured spinal cord. They showed both cell-autonomous and noncell-autonomous (trophic) effects, including synapse formation between hiPSC-NS-derived neurons and host mouse neurons, expression of neurotrophic factors, angiogenesis, axonal regrowth, and increased amounts of myelin in the injured area. These positive effects resulted in significantly better functional recovery compared with vehicle-treated control animals, and the recovery persisted through the end of the observation period, 112 d post-SCI. No tumor formation was observed in the hiPSC-NS-grafted mice. These findings suggest that hiPSCs give rise to neural stem/progenitor cells that support improved function post-SCI and are a promising cell source for its treatment.
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Respiratory function following bilateral mid-cervical contusion injury in the adult rat. Exp Neurol 2011; 235:197-210. [PMID: 21963673 DOI: 10.1016/j.expneurol.2011.09.024] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 08/27/2011] [Accepted: 09/13/2011] [Indexed: 11/22/2022]
Abstract
The consequences of spinal cord injury (SCI) are often viewed as the result of white matter damage. However, injuries occurring at any spinal level, especially in cervical and lumbar enlargement regions, also entail segmental neuronal loss. Yet, the contributions of gray matter injury and plasticity to functional outcomes are poorly understood. The present study addressed this issue by investigating changes in respiratory function following bilateral C(3)/C(4) contusion injuries at the level of the phrenic motoneuron (PhMN) pool which in the adult rat extends from C(3) to C(5/6) and provides innervation to the diaphragm. Despite extensive white and gray matter pathology associated with two magnitudes of injury severity, ventilation was relatively unaffected during both quiet breathing and respiratory challenge (hypercapnia). On the other hand, bilateral diaphragm EMG recordings revealed that the ability to increase diaphragm activity during respiratory challenge was substantially, and chronically, impaired. This deficit has not been seen following predominantly white matter lesions at higher cervical levels. Thus, the impact of gray matter damage relative to PhMNs and/or interneurons becomes evident during conditions associated with increased respiratory drive. Unaltered ventilatory behavior, despite significant deficits in diaphragm function, suggests compensatory neuroplasticity involving recruitment of other spinal respiratory networks which may entail remodeling of connections. Transynaptic tracing, using pseudorabies virus (PRV), revealed changes in PhMN-related interneuronal labeling rostral to the site of injury, thus offering insight into the potential anatomical reorganization and spinal plasticity following cervical contusion.
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Grafted neural progenitors integrate and restore synaptic connectivity across the injured spinal cord. J Neurosci 2011; 31:4675-86. [PMID: 21430166 DOI: 10.1523/jneurosci.4130-10.2011] [Citation(s) in RCA: 161] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Transplantation of neural progenitor cells (NPC) is a promising therapeutic strategy for replacing neurons lost after spinal cord injury, but significant challenges remain regarding neuronal integration and functional connectivity. Here we tested the ability of graft-derived neurons to reestablish connectivity by forming neuronal relays between injured dorsal column (DC) sensory axons and the denervated dorsal column nuclei (DCN). A mixed population of neuronal and glial restricted precursors (NRP/GRP) derived from the embryonic spinal cord of alkaline phosphatase (AP) transgenic rats were grafted acutely into a DC lesion at C1. One week later, BDNF-expressing lentivirus was injected into the DCN to guide graft axons to the intended target. Six weeks later, we observed anterogradely traced sensory axons regenerating into the graft and robust growth of graft-derived AP-positive axons along the neurotrophin gradient into the DCN. Immunoelectron microscopy revealed excitatory synaptic connections between regenerating host axons and graft-derived neurons at C1 as well as between graft axons and DCN neurons in the brainstem. Functional analysis by stimulus-evoked c-Fos expression and electrophysiological recording showed that host axons formed active synapses with graft neurons at the injury site with the signal propagating by graft axons to the DCN. We observed reproducible electrophysiological activity at the DCN with a temporal delay predicted by our relay model. These findings provide the first evidence for the ability of NPC to form a neuronal relay by extending active axons across the injured spinal cord to the intended target establishing a critical step for neural repair with stem cells.
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The role of embryonic motoneuron transplants to restore the lost motor function of the injured spinal cord. Ann Anat 2011; 193:362-70. [PMID: 21600746 DOI: 10.1016/j.aanat.2011.04.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 03/28/2011] [Accepted: 04/06/2011] [Indexed: 12/26/2022]
Abstract
Spinal cord injury or disease result in the loss of critical numbers of spinal motoneurons and consequentially, in severe functional impairment. The most successful way to replace missing motoneurons is the use of embryonic postmitotic motoneuron grafts. This method may also at least partially restore integrity of the injured spinal cord. It has been shown that grafted motoneurons survive, differentiate and integrate into the host cord and many of them are able to reinnervate the denervated muscles. If grafted motoneurons are provided with a conduit (e.g. reimplanted ventral root) the grafted cells are able to extend their axons along the entire length of the peripheral nerves and reach the hind or forelimb muscles and to restore limb locomotion patterns. Grafted motoneurons show excellent survival in motoneuron-depleted adult host cords, but the developing spinal cord appears to provide an unfavourable environment for these motoneurons as they do not survive in immature cords. The long term survival and maturation of the grafted neurons depend on the availability of a nerve conduit and one or more target muscles, independently of whether these are ectopic nerve-muscle implants or limb muscles in their original site. Thus, grafted and host motoneurons induce functional recovery in the denervated limb muscles when their axons can grow into an avulsed and reimplanted ventral root and then reach the limb muscles. Following segmental loss of motoneurons induced by partial spinal cord injury, motoneuron-enriched embryonic grafts can be placed into the gap-like hemisection cavity in the cervical spinal cord. Such transplants induce the regeneration of great numbers of host motoneurons possibly by the bridging effect of the grafts. In this case, the regenerating host motoneurons reinnervate their original target muscles while the small graft plays a minimal role in the reinnervation of muscles. These results suggest that reconstruction of the injured spinal cord using an embryonic motoneuron-enriched spinal cord graft is a feasible way to achieve improvement after severe functional motor deficits of the spinal cord.
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