1
|
Dominguez-Bajo A, Clotman F. Potential Roles of Specific Subclasses of Premotor Interneurons in Spinal Cord Function Recovery after Traumatic Spinal Cord Injury in Adults. Cells 2024; 13:652. [PMID: 38667267 PMCID: PMC11048910 DOI: 10.3390/cells13080652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 04/04/2024] [Accepted: 04/05/2024] [Indexed: 04/28/2024] Open
Abstract
The differential expression of transcription factors during embryonic development has been selected as the main feature to define the specific subclasses of spinal interneurons. However, recent studies based on single-cell RNA sequencing and transcriptomic experiments suggest that this approach might not be appropriate in the adult spinal cord, where interneurons show overlapping expression profiles, especially in the ventral region. This constitutes a major challenge for the identification and direct targeting of specific populations that could be involved in locomotor recovery after a traumatic spinal cord injury in adults. Current experimental therapies, including electrical stimulation, training, pharmacological treatments, or cell implantation, that have resulted in improvements in locomotor behavior rely on the modulation of the activity and connectivity of interneurons located in the surroundings of the lesion core for the formation of detour circuits. However, very few publications clarify the specific identity of these cells. In this work, we review the studies where premotor interneurons were able to create new intraspinal circuits after different kinds of traumatic spinal cord injury, highlighting the difficulties encountered by researchers, to classify these populations.
Collapse
Affiliation(s)
- Ana Dominguez-Bajo
- Université catholique de Louvain, Louvain Institute of Biomolecular Science and Technology (LIBST), Animal Molecular and Cellular Biology Group (AMCB), Place Croix du Sud 4–5, 1348 Louvain la Neuve, Belgium
| | - Frédéric Clotman
- Université catholique de Louvain, Louvain Institute of Biomolecular Science and Technology (LIBST), Animal Molecular and Cellular Biology Group (AMCB), Place Croix du Sud 4–5, 1348 Louvain la Neuve, Belgium
| |
Collapse
|
2
|
Pitts T, Iceman KE, Huff A, Musselwhite MN, Frazure ML, Young KC, Greene CL, Howland DR. Laryngeal and swallow dysregulation following acute cervical spinal cord injury. J Neurophysiol 2022; 128:405-417. [PMID: 35830612 PMCID: PMC9359645 DOI: 10.1152/jn.00469.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Laryngeal function is vital to airway protection. While swallow is mediated by the brainstem, mechanisms underlying increased risk of dysphagia after cervical spinal cord injury (SCI) are unknown. We hypothesized that loss of descending phrenic drive affects swallow and breathing differently, and loss of ascending spinal afferent information alters swallow regulation. We recorded electromyograms from upper airway and chest wall muscles in freely breathing pentobarbital-anesthetized cats and rats. Inspiratory laryngeal activity increased ~two-fold following C2 lateral-hemisection. Ipsilateral to the injury, crural diaphragm EMG amplitude was reduced during breathing (62 ± 25% change post-injury), but no animal had complete termination of activity; 75% of animals increased contralateral diaphragm recruitment, but this did not reach significance. During swallow, laryngeal adductor and pharyngeal constrictor muscles increased activity, and diaphragm activity was bilaterally suppressed. This was unexpected because of the ipsilateral-specific response during breathing. Swallow-breathing coordination was also disrupted and more swallows occurred during early expiration. Finally, to determine if the chest wall is a major source of feedback for laryngeal regulation, we performed T1 total transections in rats. As in the C2 lateral-hemisection, inspiratory laryngeal recruitment was the first feature noted. In contrast to the C2 lateral-hemisection, diaphragmatic drive increased after T1 transection. Overall, we found that SCI alters laryngeal drive during swallow and breathing, and reduced swallow-related diaphragm activity. Our results show behavior-specific effects, suggesting SCI affects swallow more than breathing, and emphasizes the need for additional studies on the effects of ascending afferents from the spinal cord on laryngeal function.
Collapse
Affiliation(s)
- Teresa Pitts
- Kentucky Spinal Cord Injury Center, Department of Neurological Surgery, University of Louisville, Louisville, KY, United States
| | - Kimberly E Iceman
- Kentucky Spinal Cord Injury Center, Department of Neurological Surgery, University of Louisville, Louisville, KY, United States
| | - Alyssa Huff
- Center for Integrative Brain Research, Seattle Children's Hospital, Seattle, WA, United States
| | - Matthew Nicholas Musselwhite
- Kentucky Spinal Cord Injury Center, Department of Neurological Surgery, University of Louisville, Louisville, KY, United States
| | - Michael L Frazure
- Kentucky Spinal Cord Injury Center, Department of Neurological Surgery, University of Louisville, Louisville, KY, United States
| | - Kellyanna C Young
- Kentucky Spinal Cord Injury Center, Department of Neurological Surgery, University of Louisville, Louisville, KY, United States
| | - Clinton L Greene
- Kentucky Spinal Cord Injury Center, Department of Neurological Surgery, University of Louisville, Louisville, KY, United States
| | - Dena Ruth Howland
- Kentucky Spinal Cord Injury Center, Department of Neurological Surgery, University of Louisville, Louisville, KY, United States.,Research Service, Robley Rex VA Medical Center, Louisville, KY, United States
| |
Collapse
|
3
|
Yao Q, Guan J, Ma L, Cheng L, Duan F, Xu F, Zhao W, Duan W, Wu H, Chen Z, Jian F. Wireless Epidural Electrical Stimulation in Combination With Serotonin Agonists Improves Intraspinal Metabolism in Spinal Cord Injury Rats. Neuromodulation 2020; 24:416-426. [PMID: 33377590 DOI: 10.1111/ner.13344] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 11/14/2020] [Accepted: 11/30/2020] [Indexed: 12/25/2022]
Abstract
OBJECTIVES The combination of epidural electrical stimulation (EES) and serotonin agonists (5-HTA) effectively restores rhythmic lower-limb movements and improves intraspinal hemodynamics after spinal cord injury (SCI). Nonetheless, whether EES + 5-HTA improves intraspinal metabolism remains unclear. The present study aimed to evaluate the effects of EES + 5-HTA on intraspinal metabolism in SCI rats. MATERIALS AND METHODS Wireless EES (WEES) implantation with complete T8 transection was performed in SCI rats. Electrodes were placed at the T12 and L2 vertebral levels. After rest for a week, the SCI rats received 11 weeks of WEES + 5-HTA treatment and treadmill training. WEES was switched off after each daily training. Locomotor function was evaluated by motion capture at week 12. Positron emission tomography-computed tomography was conducted to evaluate basal metabolism when WEES was switched off and assess task metabolism when WEES was switched on. RESULTS With locomotor recovery after training for 11 weeks, WEES + 5-HTA conjointly improved basal metabolism (vs. each intervention alone; p < 0.05) and linearly modulated task metabolism in a frequency-dependent manner (R2 = 0.8901). Furthermore, 60 Hz of WEES was identified as the threshold for the extensive activation of the spinal cord's task metabolism below the transection plane (p < 0.05). CONCLUSIONS WEES + 5-HTA could conjointly restore basal metabolism to a healthy level and modulate task metabolism by adjusting the stimulation frequency.
Collapse
Affiliation(s)
- Qingyu Yao
- Department of Neurosurgery, China International Neuroscience Institute (CHINA-INI), Xuanwu Hospital, Capital Medical University, Beijing, China.,Research Center of Spine and Spinal Cord, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,Lab of Spinal Cord Injury and Functional Reconstruction, China International Neuroscience Institute (CHINA-INI), Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Jian Guan
- Department of Neurosurgery, China International Neuroscience Institute (CHINA-INI), Xuanwu Hospital, Capital Medical University, Beijing, China.,Research Center of Spine and Spinal Cord, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,Lab of Spinal Cord Injury and Functional Reconstruction, China International Neuroscience Institute (CHINA-INI), Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Longbing Ma
- Department of Neurosurgery, China International Neuroscience Institute (CHINA-INI), Xuanwu Hospital, Capital Medical University, Beijing, China.,Research Center of Spine and Spinal Cord, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,Lab of Spinal Cord Injury and Functional Reconstruction, China International Neuroscience Institute (CHINA-INI), Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Lei Cheng
- Department of Neurosurgery, China International Neuroscience Institute (CHINA-INI), Xuanwu Hospital, Capital Medical University, Beijing, China.,Research Center of Spine and Spinal Cord, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,Lab of Spinal Cord Injury and Functional Reconstruction, China International Neuroscience Institute (CHINA-INI), Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Feng Duan
- College of Artificial Intelligence, Nankai University, Tianjin, China
| | - Fu Xu
- School of Aerospace Engineering, Tsinghua University, Beijing, China
| | - Wang Zhao
- Department of Management Science, University of Strathclyde, Glasgow, UK
| | - Wanru Duan
- Department of Neurosurgery, China International Neuroscience Institute (CHINA-INI), Xuanwu Hospital, Capital Medical University, Beijing, China.,Research Center of Spine and Spinal Cord, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,Lab of Spinal Cord Injury and Functional Reconstruction, China International Neuroscience Institute (CHINA-INI), Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Hao Wu
- Department of Neurosurgery, China International Neuroscience Institute (CHINA-INI), Xuanwu Hospital, Capital Medical University, Beijing, China.,Research Center of Spine and Spinal Cord, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,Lab of Spinal Cord Injury and Functional Reconstruction, China International Neuroscience Institute (CHINA-INI), Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Zan Chen
- Department of Neurosurgery, China International Neuroscience Institute (CHINA-INI), Xuanwu Hospital, Capital Medical University, Beijing, China.,Research Center of Spine and Spinal Cord, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,Lab of Spinal Cord Injury and Functional Reconstruction, China International Neuroscience Institute (CHINA-INI), Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Fengzeng Jian
- Department of Neurosurgery, China International Neuroscience Institute (CHINA-INI), Xuanwu Hospital, Capital Medical University, Beijing, China.,Research Center of Spine and Spinal Cord, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,Lab of Spinal Cord Injury and Functional Reconstruction, China International Neuroscience Institute (CHINA-INI), Xuanwu Hospital, Capital Medical University, Beijing, China
| |
Collapse
|
4
|
Ford TW, Kirkwood PA. Bulbospinal connections to intercostal motoneurones following a chronic lateral spinal cord lesion. Respir Physiol Neurobiol 2020; 284:103566. [PMID: 33129988 DOI: 10.1016/j.resp.2020.103566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 10/17/2020] [Accepted: 10/20/2020] [Indexed: 10/23/2022]
Abstract
Previous evidence from electrophysiological experiments in anaesthetized cats with a chronic lateral lesion of the lower thoracic spinal cord indicated an expansion of the functional projections of expiratory bulbospinal neurones (EBSNs) in the segment above the lesion, measured at 16 weeks post-lesion. Here we investigate connections made by the same EBSNs to motoneurones in that segment, using cross-correlations between their discharges. The connections to the internal intercostal nerve motoneurones were found to be no different from controls. However, a significant increase was found in the number of connections between EBSNs and γ motoneurones of the external intercostal nerve (8/24, compared to 1/16) with possibly additional connections to the α motoneurones of the same nerve. Increased connections to the γ motoneurones of the internal intercostal nerve could not be ruled out. The expanded functional projections are thus likely to include new connections to γ motoneurones. We suggest that γ motoneurones may be inherently more receptive to new inputs. If so, the previously discounted role of abnormal fusimotor discharges in motor disorders would be worth reconsideration.
Collapse
Affiliation(s)
- Timothy W Ford
- Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Peter A Kirkwood
- Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, UK.
| |
Collapse
|
5
|
Meehan CF, Ford TW, Kirkwood PA. Plasticity of thoracic interneurones rostral to a lateral spinal cord lesion. Exp Neurol 2020; 331:113361. [PMID: 32464119 DOI: 10.1016/j.expneurol.2020.113361] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Revised: 05/03/2020] [Accepted: 05/17/2020] [Indexed: 01/14/2023]
Abstract
The morphology and projections of ventral horn interneurones in the segment above an ipsilateral thoracic lateral spinal cord lesion were studied in the cat by intracellular injections of Neurobiotin at 6 to 18 weeks post-lesion and compared with previously published control data from uninjured spinal cords. The cell axons ascended, descended or both, mostly contralaterally and mostly spared by the lesion. Unusual morphological dendritic features were seen in the lesion group, mostly growth-related, including complex dendritic appendages, twisted or multiple-branched terminal dendrites, commissural dendrites, apparently swollen proximal dendrites and rostrocaudal asymmetries. Significant quantitative differences included more dendritic spines in the lesion group (3.4×) and smaller soma areas in the lesion group (with similar numbers of primary dendrites and rostrocaudal dendritic spans). Immunoreactivity to microtubule associated protein 2a/b was detected in the proximal, but not distal, dendrites of cells in the lesion group, corresponding to an overall decrease in immunoreactivity in the ventral horns on the lesion side compared to the other. For axon collaterals, significant increases for the lesion group were seen in the number of collaterals in the first 4 mm of axon and in the area of ventral/intermediate horn occupied by terminals, including increased innervation of some regions, among which were the intermediolateral columns. This dendritic and axonal plasticity makes the interneuones candidates for a role in detour circuits but also for a maladaptive role in autonomic hyperreflexia.
Collapse
Affiliation(s)
- Claire Francesca Meehan
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK.
| | - Timothy W Ford
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Peter A Kirkwood
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| |
Collapse
|
6
|
Jensen VN, Alilain WJ, Crone SA. Role of Propriospinal Neurons in Control of Respiratory Muscles and Recovery of Breathing Following Injury. Front Syst Neurosci 2020; 13:84. [PMID: 32009911 PMCID: PMC6978673 DOI: 10.3389/fnsys.2019.00084] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 12/16/2019] [Indexed: 12/20/2022] Open
Abstract
Respiratory motor failure is the leading cause of death in spinal cord injury (SCI). Cervical injuries disrupt connections between brainstem neurons that are the primary source of excitatory drive to respiratory motor neurons in the spinal cord and their targets. In addition to direct connections from bulbospinal neurons, respiratory motor neurons also receive excitatory and inhibitory inputs from propriospinal neurons, yet their role in the control of breathing is often overlooked. In this review, we will present evidence that propriospinal neurons play important roles in patterning muscle activity for breathing. These roles likely include shaping the pattern of respiratory motor output, processing and transmitting sensory afferent information, coordinating ventilation with motor activity, and regulating accessory and respiratory muscle activity. In addition, we discuss recent studies that have highlighted the importance of propriospinal neurons for recovery of respiratory muscle function following SCI. We propose that molecular genetic approaches to target specific developmental neuron classes in the spinal cord would help investigators resolve the many roles of propriospinal neurons in the control of breathing. A better understanding of how spinal circuits pattern breathing could lead to new treatments to improve breathing following injury or disease.
Collapse
Affiliation(s)
- Victoria N. Jensen
- Neuroscience Graduate Program, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Warren J. Alilain
- Spinal Cord and Brain Injury Research Center, University of Kentucky College of Medicine, Lexington, KY, United States,Department of Neuroscience, University of Kentucky College of Medicine, Lexington, KY, United States
| | - Steven A. Crone
- Division of Neurosurgery, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States,Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States,Department of Neurosurgery, University of Cincinnati College of Medicine, Cincinnati, OH, United States,*Correspondence: Steven A. Crone
| |
Collapse
|
7
|
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.
Collapse
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
| |
Collapse
|
8
|
Santamaría AJ, Benavides FD, DiFede DL, Khan A, Pujol MV, Dietrich WD, Marttos A, Green BA, Hare JM, Guest JD. Clinical and Neurophysiological Changes after Targeted Intrathecal Injections of Bone Marrow Stem Cells in a C3 Tetraplegic Subject. J Neurotrauma 2018; 36:500-516. [PMID: 29790404 DOI: 10.1089/neu.2018.5716] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
High-level quadriplegia is a devastating condition with limited treatment options. Bone marrow derived stem cells (BMSCs) are reported to have immunomodulatory and neurotrophic effects in spinal cord injury (SCI). We report a subject with complete C2 SCI who received three anatomically targeted intrathecal infusions of BMSCs under a single-patient expanded access investigational new drug (IND). She underwent intensive physical therapy and was followed for >2 years. At end-point, her American Spinal Injury Association Impairment Scale (AIS) grade improved from A to B, and she recovered focal pressure touch sensation over several body areas. We conducted serial neurophysiological testing to monitor changes in residual connectivity. Motor, sensory, and autonomic system testing included motor evoked potentials (MEPs), somatosensory evoked potentials (SSEPs), electromyography (EMG) recordings, F waves, galvanic skin responses, and tilt-table responses. The quality and magnitude of voluntary EMG activations increased over time, but remained below the threshold of clinically obvious movement. Unexpectedly, at 14 months post-injury, deep inspiratory maneuvers triggered respiratory-like EMG bursting in the biceps and several other muscles. This finding means that connections between respiratory neurons and motor neurons were newly established, or unmasked. We also report serial analysis of MRI, International Standards for Neurological Classification of SCI (ISNCSCI), pulmonary function, pain scores, cerebrospinal fluid (CSF) cytokines, and bladder assessment. As a single case, the linkage of the clinical and neurophysiological changes to either natural history or to the BMSC infusions cannot be resolved. Nevertheless, such detailed neurophysiological assessment of high cervical SCI patients is rarely performed. Our findings indicate that electrophysiology studies are sensitive to define both residual connectivity and new plasticity.
Collapse
Affiliation(s)
- Andrea J Santamaría
- 1 The Miami Project to Cure Paralysis, University of Miami, Miller School of Medicine, Miami, Florida
| | - Francisco D Benavides
- 1 The Miami Project to Cure Paralysis, University of Miami, Miller School of Medicine, Miami, Florida
| | - Darcy L DiFede
- 2 Interdisciplinary Stem Cell Institute, University of Miami, Miller School of Medicine, Miami, Florida
| | - Aisha Khan
- 2 Interdisciplinary Stem Cell Institute, University of Miami, Miller School of Medicine, Miami, Florida
| | - Marietsy V Pujol
- 2 Interdisciplinary Stem Cell Institute, University of Miami, Miller School of Medicine, Miami, Florida
| | - W Dalton Dietrich
- 1 The Miami Project to Cure Paralysis, University of Miami, Miller School of Medicine, Miami, Florida.,3 Department of Neurological Surgery, University of Miami, Miller School of Medicine, Miami, Florida
| | - Antonio Marttos
- 4 Surgical Critical Care, University of Miami, Miller School of Medicine, Miami, Florida
| | - Barth A Green
- 3 Department of Neurological Surgery, University of Miami, Miller School of Medicine, Miami, Florida
| | - Joshua M Hare
- 2 Interdisciplinary Stem Cell Institute, University of Miami, Miller School of Medicine, Miami, Florida
| | - James D Guest
- 1 The Miami Project to Cure Paralysis, University of Miami, Miller School of Medicine, Miami, Florida.,3 Department of Neurological Surgery, University of Miami, Miller School of Medicine, Miami, Florida
| |
Collapse
|
9
|
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.
Collapse
|
10
|
Jones SE, Dutschmann M. Testing the hypothesis of neurodegeneracy in respiratory network function with a priori transected arterially perfused brain stem preparation of rat. J Neurophysiol 2016; 115:2593-607. [PMID: 26888109 DOI: 10.1152/jn.01073.2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 02/12/2016] [Indexed: 11/22/2022] Open
Abstract
Degeneracy of respiratory network function would imply that anatomically discrete aspects of the brain stem are capable of producing respiratory rhythm. To test this theory we a priori transected brain stem preparations before reperfusion and reoxygenation at 4 rostrocaudal levels: 1.5 mm caudal to obex (n = 5), at obex (n = 5), and 1.5 (n = 7) and 3 mm (n = 6) rostral to obex. The respiratory activity of these preparations was assessed via recordings of phrenic and vagal nerves and lumbar spinal expiratory motor output. Preparations with a priori transection at level of the caudal brain stem did not produce stable rhythmic respiratory bursting, even when the arterial chemoreceptors were stimulated with sodium cyanide (NaCN). Reperfusion of brain stems that preserved the pre-Bötzinger complex (pre-BötC) showed spontaneous and sustained rhythmic respiratory bursting at low phrenic nerve activity (PNA) amplitude that occurred simultaneously in all respiratory motor outputs. We refer to this rhythm as the pre-BötC burstlet-type rhythm. Conserving circuitry up to the pontomedullary junction consistently produced robust high-amplitude PNA at lower burst rates, whereas sequential motor patterning across the respiratory motor outputs remained absent. Some of the rostrally transected preparations expressed both burstlet-type and regular PNA amplitude rhythms. Further analysis showed that the burstlet-type rhythm and high-amplitude PNA had 1:2 quantal relation, with burstlets appearing to trigger high-amplitude bursts. We conclude that no degenerate rhythmogenic circuits are located in the caudal medulla oblongata and confirm the pre-BötC as the primary rhythmogenic kernel. The absence of sequential motor patterning in a priori transected preparations suggests that pontine circuits govern respiratory pattern formation.
Collapse
Affiliation(s)
- Sarah E Jones
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria, Australia
| | - Mathias Dutschmann
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria, Australia
| |
Collapse
|