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Yadav A, Dabur R. Skeletal muscle atrophy after sciatic nerve damage: Mechanistic insights. Eur J Pharmacol 2024; 970:176506. [PMID: 38492879 DOI: 10.1016/j.ejphar.2024.176506] [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: 01/08/2024] [Revised: 03/13/2024] [Accepted: 03/14/2024] [Indexed: 03/18/2024]
Abstract
Sciatic nerve injury leads to molecular events that cause muscular dysfunction advancement in atrophic conditions. Nerve damage renders muscles permanently relaxed which elevates intracellular resting Ca2+ levels. Increased Ca2+ levels are associated with several cellular signaling pathways including AMPK, cGMP, PLC-β, CERB, and calcineurin. Also, multiple enzymes involved in the tricarboxylic acid cycle and oxidative phosphorylation are activated by Ca2+ influx into mitochondria during muscle contraction, to meet increased ATP demand. Nerve damage induces mitophagy and skeletal muscle atrophy through increased sensitivity to Ca2+-induced opening of the permeability transition pore (PTP) in mitochondria attributed to Ca2+, ROS, and AMPK overload in muscle. Activated AMPK interacts negatively with Akt/mTOR is a highly prevalent and well-described central pathway for anabolic processes. Over the decade several reports indicate abnormal behavior of signaling machinery involved in denervation-induced muscle loss but end up with some controversial outcomes. Therefore, understanding how the synthesis and inhibitory stimuli interact with cellular signaling to control muscle mass and morphology may lead to new pharmacological insights toward understanding the underlying mechanism of muscle loss after sciatic nerve damage. Hence, the present review summarizes the existing literature on denervation-induced muscle atrophy to evaluate the regulation and expression of differential regulators during sciatic damage.
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Affiliation(s)
- Aarti Yadav
- Clinical Biochemistry Laboratory, Department of Biochemistry, Maharshi Dayanand University, Rohtak, 124001, Haryana, India
| | - Rajesh Dabur
- Clinical Biochemistry Laboratory, Department of Biochemistry, Maharshi Dayanand University, Rohtak, 124001, Haryana, India.
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Rink-Notzon S, Reuscher J, Wollny L, Sarikcioglu L, Bilmen S, Manthou M, Gordon T, Angelov DN. Appropriate dosage, timing, and site of intramuscular injections of brain-derived neurotrophic factor (BDNF) promote motor recovery after facial nerve injury in rats. Muscle Nerve 2024; 69:490-497. [PMID: 38328996 DOI: 10.1002/mus.28051] [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: 07/18/2023] [Revised: 01/18/2024] [Accepted: 01/21/2024] [Indexed: 02/09/2024]
Abstract
INTRODUCTION/AIMS Daily intramuscular injections of fibroblast growth factor 2 (FGF2) but not of brain-derived neurotrophic factor (BDNF) significantly improve whisking behavior and mono-innervation of the rat levator labii superioris (LLS) muscle 56 days after buccal nerve transection and suture (buccal-buccal anastomosis, BBA). We explored the dose-response of BDNF, FGF2, and insulin growth factor 2 (IGF2) on the same parameters, asking whether higher doses of BDNF would promote recovery. METHODS After BBA, growth factors were injected (30 μL volume) daily into the LLS muscle over 14, 28, or 56 days. At 56 days, video-based motion analysis of vibrissal whisking was performed and the extent of mono- and poly-reinnervation of the reinnervated neuromuscular junctions (NMJs) of the muscle determined with immunostaining of the nerve with β-tubulin and histochemical staining of the endplates with Alexa Fluor 488-conjugated α-bungarotoxin. RESULTS The dose-response curve demonstrated significantly higher whisking amplitudes and corresponding increased mono-innervation of the NMJ in the reinnervated LLS muscle at concentrations of 20-30 μg/mL BDNF administered daily for 14-28 days after BBA surgery. In contrast, high doses of IGF2 and FGF2, or doses of 20 and 40 μg/mL of BDNF administered for 14-56 days had no effect on either whisking behavior or in reducing poly-reinnervation of endplates in the muscle. DISCUSSION These data suggest that the re-establishment of mono-innervation of whiskerpad muscles and the improved motor function by injections of BDNF into the paralyzed vibrissal musculature after facial nerve injury have translation potential and promote clinical application.
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Affiliation(s)
- Svenja Rink-Notzon
- Department of Prosthetic Dentistry, School of Dental and Oral Medicine, University of Cologne, Cologne, Germany
| | - Jannika Reuscher
- Department of Anatomy II, University of Cologne, Cologne, Germany
| | - Laura Wollny
- Department of Anatomy II, University of Cologne, Cologne, Germany
| | | | - Süreyya Bilmen
- Vocational School of Health Services, Akdeniz University, Antalya, Turkey
| | - Marilena Manthou
- Department of Histology and Embryology, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Tessa Gordon
- Department of Surgery, The Hospital for Sick Children, Toronto, Ontario, Canada
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Doherty C, Lodyga M, Correa J, Di Ciano-Oliveira C, Plant PJ, Bain JR, Batt J. Utilization of the Rat Tibial Nerve Transection Model to Evaluate Cellular and Molecular Mechanisms Underpinning Denervation-Mediated Muscle Injury. Int J Mol Sci 2024; 25:1847. [PMID: 38339124 PMCID: PMC10855399 DOI: 10.3390/ijms25031847] [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: 12/23/2023] [Revised: 01/19/2024] [Accepted: 01/28/2024] [Indexed: 02/12/2024] Open
Abstract
Peripheral nerve injury denervates muscle, resulting in muscle paralysis and atrophy. This is reversible if timely muscle reinnervation occurs. With delayed reinnervation, the muscle's reparative ability declines, and muscle-resident fibro-adipogenic progenitor cells (FAPs) proliferate and differentiate, inducing fibro-fatty muscle degradation and thereby physical disability. The mechanisms by which the peripheral nerve regulates FAPs expansion and differentiation are incompletely understood. Using the rat tibial neve transection model, we demonstrated an increased FAPs content and a changing FAPs phenotype, with an increased capacity for adipocyte and fibroblast differentiation, in gastrocnemius muscle post-denervation. The FAPs response was inhibited by immediate tibial nerve repair with muscle reinnervation via neuromuscular junctions (NMJs) and sensory organs (e.g., muscle spindles) or the sensory protection of muscle (where a pure sensory nerve is sutured to the distal tibial nerve stump) with reinnervation by muscle spindles alone. We found that both procedures reduced denervation-mediated increases in glial-cell-line-derived neurotrophic factor (GDNF) in muscle and that GDNF promoted FAPs adipogenic and fibrogenic differentiation in vitro. These results suggest that the peripheral nerve controls FAPs recruitment and differentiation via the modulation of muscle GDNF expression through NMJs and muscle spindles. GDNF can serve as a therapeutic target in the management of denervation-induced muscle injury.
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Affiliation(s)
- Christina Doherty
- Keenan Research Center for Biomedical Science, St. Michael’s Hospital, Unity Health Toronto, Toronto, ON M5B 1T8, Canada; (C.D.); (M.L.); (J.C.); (C.D.C.-O.); (P.J.P.)
| | - Monika Lodyga
- Keenan Research Center for Biomedical Science, St. Michael’s Hospital, Unity Health Toronto, Toronto, ON M5B 1T8, Canada; (C.D.); (M.L.); (J.C.); (C.D.C.-O.); (P.J.P.)
| | - Judy Correa
- Keenan Research Center for Biomedical Science, St. Michael’s Hospital, Unity Health Toronto, Toronto, ON M5B 1T8, Canada; (C.D.); (M.L.); (J.C.); (C.D.C.-O.); (P.J.P.)
| | - Caterina Di Ciano-Oliveira
- Keenan Research Center for Biomedical Science, St. Michael’s Hospital, Unity Health Toronto, Toronto, ON M5B 1T8, Canada; (C.D.); (M.L.); (J.C.); (C.D.C.-O.); (P.J.P.)
| | - Pamela J. Plant
- Keenan Research Center for Biomedical Science, St. Michael’s Hospital, Unity Health Toronto, Toronto, ON M5B 1T8, Canada; (C.D.); (M.L.); (J.C.); (C.D.C.-O.); (P.J.P.)
| | - James R. Bain
- Division of Plastic Surgery, Faculty of Health Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada;
| | - Jane Batt
- Keenan Research Center for Biomedical Science, St. Michael’s Hospital, Unity Health Toronto, Toronto, ON M5B 1T8, Canada; (C.D.); (M.L.); (J.C.); (C.D.C.-O.); (P.J.P.)
- Department of Medicine, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5S 3H2, Canada
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Iwasaki T, Akeda K, Kawaguchi K, Yamada J, Hasegawa T, Takegami N, Fujiwara T, Sudo A. Expression of Glial-Cell-Line-Derived Neurotrophic Factor Family Ligands in Human Intervertebral Discs. Int J Mol Sci 2023; 24:15874. [PMID: 37958856 PMCID: PMC10649213 DOI: 10.3390/ijms242115874] [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: 09/05/2023] [Revised: 10/25/2023] [Accepted: 10/31/2023] [Indexed: 11/15/2023] Open
Abstract
Glial-cell-line-derived neurotrophic factor (GDNF) family ligands (GFLs) contribute to the sensitization of primary afferents and are involved in the pathogenesis of inflammatory pain. The purpose of this preliminary study was to examine the expression of other GFLs (neurturin (NRTN), artemin (ARTN), persephin (PSPN)) and receptors in human IVD cells and tissues exhibiting early and advanced stages of degeneration. Human IVD cells were cultured as a monolayer after isolation from the nucleus pulposus (NP) and anulus fibrosus (AF) tissues. The mRNA expression of NRTN, ARTN, PSPN, and their receptors (GFRA2-GFRA4) was quantified using real-time PCR. Protein expression was evaluated using immunohistochemistry and Western blotting. The expression of NRTN, ARTN, PSPN, and their co-receptors (GFRA2-GFRA4) was identified in human IVD cells at both mRNA and protein levels. A trend was noted wherein the mRNA expression of ARTN, PSPN, and GFRA2 was upregulated by IL-1β treatment in a dose-dependent manner. The percentages of immunopositive cells in the advanced degenerate stage of ARTN, PSPN, and GFRA2 were significantly higher than those in the early degenerate stage. Their expression was enhanced in advanced tissue degeneration, which suggests that GFLs (ARTN and PSPN) may be involved in the pathogenesis of discogenic pain.
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Affiliation(s)
| | - Koji Akeda
- Department of Orthopedic Surgery, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu City 514-8507, Mie, Japan; (T.I.); (K.K.); (J.Y.); (T.H.); (N.T.); (T.F.); (A.S.)
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The Cellular and Molecular Signature of ALS in Muscle. J Pers Med 2022; 12:jpm12111868. [PMID: 36579600 PMCID: PMC9692882 DOI: 10.3390/jpm12111868] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 10/29/2022] [Accepted: 11/01/2022] [Indexed: 11/11/2022] Open
Abstract
Amyotrophic lateral sclerosis is a disease affecting upper and lower motor neurons. Although motor neuron death is the core event of ALS pathology, it is increasingly recognized that other tissues and cell types are affected in the disease, making potentially major contributions to the occurrence and progression of pathology. We review here the known cellular and molecular characteristics of muscle tissue affected by ALS. Evidence of toxicity in skeletal muscle tissue is considered, including metabolic dysfunctions, impaired proteostasis, and deficits in muscle regeneration and RNA metabolism. The role of muscle as a secretory organ, and effects on the skeletal muscle secretome are also covered, including the increase in secretion of toxic factors or decrease in essential factors that have consequences for neuronal function and survival.
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6
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Tereshenko V, Dotzauer DC, Luft M, Ortmayr J, Maierhofer U, Schmoll M, Festin C, Carrero Rojas G, Klepetko J, Laengle G, Politikou O, Farina D, Blumer R, Bergmeister KD, Aszmann OC. Autonomic Nerve Fibers Aberrantly Reinnervate Denervated Facial Muscles and Alter Muscle Fiber Population. J Neurosci 2022; 42:8297-8307. [PMID: 36216502 PMCID: PMC9653283 DOI: 10.1523/jneurosci.0670-22.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 08/17/2022] [Accepted: 08/24/2022] [Indexed: 11/27/2022] Open
Abstract
The surgical redirection of efferent neural input to a denervated muscle via a nerve transfer can reestablish neuromuscular control after nerve injuries. The role of autonomic nerve fibers during the process of muscular reinnervation remains largely unknown. Here, we investigated the neurobiological mechanisms behind the spontaneous functional recovery of denervated facial muscles in male rodents. Recovered facial muscles demonstrated an abundance of cholinergic axonal endings establishing functional neuromuscular junctions. The parasympathetic source of the neuronal input was confirmed to be in the pterygopalatine ganglion. Furthermore, the autonomically reinnervated facial muscles underwent a muscle fiber change to a purely intermediate muscle fiber population myosin heavy chain type IIa. Finally, electrophysiological tests revealed that the postganglionic parasympathetic fibers travel to the facial muscles via the sensory infraorbital nerve. Our findings demonstrated expanded neuromuscular plasticity of denervated striated muscles enabling functional recovery via alien autonomic fibers. These findings may further explain the underlying mechanisms of sensory protection implemented to prevent atrophy of a denervated muscle.SIGNIFICANCE STATEMENT Nerve injuries represent significant morbidity and disability for patients. Rewiring motor nerve fibers to other target muscles has shown to be a successful approach in the restoration of motor function. This demonstrates the remarkable capacity of the CNS to adapt to the needs of the neuromuscular system. Yet, the capability of skeletal muscles being reinnervated by nonmotor axons remains largely unknown. Here, we show that under deprivation of original efferent input, the neuromuscular system can undergo functional and morphologic remodeling via autonomic nerve fibers. This may explain neurobiological mechanisms of the sensory protection phenomenon, which is because of parasympathetic reinnervation.
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Affiliation(s)
- Vlad Tereshenko
- Clinical Laboratory for Bionic Extremity Reconstruction, Department of Plastic, Reconstructive, and Aesthetic Surgery, Medical University of Vienna, 1090 Vienna, Austria
- Centers for Biomedical Research, Medical University of Vienna, 1090 Vienna, Austria
- Department of Orthopedics and Trauma Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Dominik C Dotzauer
- Clinical Laboratory for Bionic Extremity Reconstruction, Department of Plastic, Reconstructive, and Aesthetic Surgery, Medical University of Vienna, 1090 Vienna, Austria
- Centers for Biomedical Research, Medical University of Vienna, 1090 Vienna, Austria
| | - Matthias Luft
- Clinical Laboratory for Bionic Extremity Reconstruction, Department of Plastic, Reconstructive, and Aesthetic Surgery, Medical University of Vienna, 1090 Vienna, Austria
- Centers for Biomedical Research, Medical University of Vienna, 1090 Vienna, Austria
| | - Joachim Ortmayr
- Clinical Laboratory for Bionic Extremity Reconstruction, Department of Plastic, Reconstructive, and Aesthetic Surgery, Medical University of Vienna, 1090 Vienna, Austria
- Centers for Biomedical Research, Medical University of Vienna, 1090 Vienna, Austria
| | - Udo Maierhofer
- Clinical Laboratory for Bionic Extremity Reconstruction, Department of Plastic, Reconstructive, and Aesthetic Surgery, Medical University of Vienna, 1090 Vienna, Austria
- Centers for Biomedical Research, Medical University of Vienna, 1090 Vienna, Austria
| | | | - Christopher Festin
- Clinical Laboratory for Bionic Extremity Reconstruction, Department of Plastic, Reconstructive, and Aesthetic Surgery, Medical University of Vienna, 1090 Vienna, Austria
- Centers for Biomedical Research, Medical University of Vienna, 1090 Vienna, Austria
| | | | - Johanna Klepetko
- Clinical Laboratory for Bionic Extremity Reconstruction, Department of Plastic, Reconstructive, and Aesthetic Surgery, Medical University of Vienna, 1090 Vienna, Austria
- Centers for Biomedical Research, Medical University of Vienna, 1090 Vienna, Austria
| | - Gregor Laengle
- Clinical Laboratory for Bionic Extremity Reconstruction, Department of Plastic, Reconstructive, and Aesthetic Surgery, Medical University of Vienna, 1090 Vienna, Austria
- Centers for Biomedical Research, Medical University of Vienna, 1090 Vienna, Austria
| | - Olga Politikou
- Clinical Laboratory for Bionic Extremity Reconstruction, Department of Plastic, Reconstructive, and Aesthetic Surgery, Medical University of Vienna, 1090 Vienna, Austria
- Centers for Biomedical Research, Medical University of Vienna, 1090 Vienna, Austria
| | - Dario Farina
- Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom
| | | | - Konstantin D Bergmeister
- Clinical Laboratory for Bionic Extremity Reconstruction, Department of Plastic, Reconstructive, and Aesthetic Surgery, Medical University of Vienna, 1090 Vienna, Austria
- Centers for Biomedical Research, Medical University of Vienna, 1090 Vienna, Austria
- Department of Plastic, Aesthetic, and Reconstructive Surgery, Karl Landsteiner University of Health Sciences, University Hospital, A-3500 Krems an der Donau, Austria
| | - Oskar C Aszmann
- Clinical Laboratory for Bionic Extremity Reconstruction, Department of Plastic, Reconstructive, and Aesthetic Surgery, Medical University of Vienna, 1090 Vienna, Austria
- Department of Plastic, Reconstructive, and Aesthetic Surgery, Medical University of Vienna, 1090 Vienna, Austria
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7
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Bolívar S, Udina E. Preferential regeneration and collateral dynamics of motor and sensory neurons after nerve injury in mice. Exp Neurol 2022; 358:114227. [PMID: 36108714 DOI: 10.1016/j.expneurol.2022.114227] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 08/26/2022] [Accepted: 09/08/2022] [Indexed: 11/04/2022]
Abstract
Specificity in regeneration after peripheral nerve injuries is a major determinant of functional recovery. Unfortunately, regenerating motor and sensory axons rarely find their original pathways to reinnervate appropriate target organs. Although a preference of motor axons to regenerate towards the muscle has been described, little is known about the specificity of the heterogeneous sensory populations. Here, we propose the comparative study of regeneration in different neuron subtypes. Using female and male reporter mice, we assessed the regenerative preference of motoneurons (ChAT-Cre/Ai9), proprioceptors (PV-Cre/Ai9), and cutaneous mechanoreceptors (Npy2r-Cre/Ai9). The femoral nerve of these animals was transected above the bifurcation and repaired with fibrin glue. Regeneration was assessed by applying retrograde tracers in the distal branches of the nerve 1 or 8 weeks after the lesion and counting the retrotraced somas and the axons in the branches. We found that cutaneous mechanoreceptors regenerated faster than other populations, followed by motoneurons and, lastly, proprioceptors. All neuron types had an early preference to regenerate into the cutaneous branch whereas, at long term, all neurons regenerated more through their original branch. Finally, we found that myelinated neurons extend more regenerative sprouts in the cutaneous than in the muscle branch of the femoral nerve and, particularly, that motoneurons have more collaterals than proprioceptors. Our findings reveal novel differences in regeneration dynamics and specificity, which indicate distinct regenerative mechanisms between neuron subtypes that can be potentially modulated to improve functional recovery after nerve injury.
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Affiliation(s)
- Sara Bolívar
- Institute of Neurosciences, Department Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 08193 Bellaterra, Spain
| | - Esther Udina
- Institute of Neurosciences, Department Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 08193 Bellaterra, Spain.
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8
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Adidharma W, Khouri AN, Lee JC, Vanderboll K, Kung TA, Cederna PS, Kemp SWP. Sensory nerve regeneration and reinnervation in muscle following peripheral nerve injury. Muscle Nerve 2022; 66:384-396. [PMID: 35779064 DOI: 10.1002/mus.27661] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 06/09/2022] [Accepted: 06/11/2022] [Indexed: 11/11/2022]
Abstract
Sensory afferent fibers are an important component of motor nerves and compose the majority of axons in many nerves traditionally thought of as "pure" motor nerves. These sensory afferent fibers innervate special sensory end organs in muscle, including muscle spindles that respond to changes in muscle length and Golgi tendons that detect muscle tension. Both play a major role in proprioception, sensorimotor extremity control feedback, and force regulation. After peripheral nerve injury, there is histological and electrophysiological evidence that sensory afferents can reinnervate muscle, including muscle that was not the nerve's original target. Reinnervation can occur after different nerve injury and muscle models, including muscle graft, crush, and transection injuries, and occurs in a nonspecific manner, allowing for cross-innervation to occur. Evidence of cross-innervation includes the following: muscle spindle and Golgi tendon afferent-receptor mismatch, vagal sensory fiber reinnervation of muscle, and cutaneous afferent reinnervation of muscle spindle or Golgi tendons. There are several notable clinical applications of sensory reinnervation and cross-reinnervation of muscle, including restoration of optimal motor control after peripheral nerve repair, flap sensation, sensory protection of denervated muscle, neuroma treatment and prevention, and facilitation of prosthetic sensorimotor control. This review focuses on sensory nerve regeneration and reinnervation in muscle, and the clinical applications of this phenomena. Understanding the physiology and limitations of sensory nerve regeneration and reinnervation in muscle may ultimately facilitate improvement of its clinical applications.
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Affiliation(s)
- Widya Adidharma
- Department of Surgery, Section of Plastic Surgery, University of Michigan Health System, Ann Arbor, Michigan
| | - Alexander N Khouri
- Department of Surgery, Section of Plastic Surgery, University of Michigan Health System, Ann Arbor, Michigan
| | - Jennifer C Lee
- Department of Surgery, Section of Plastic Surgery, University of Michigan Health System, Ann Arbor, Michigan
| | - Kathryn Vanderboll
- Department of Surgery, Section of Plastic Surgery, University of Michigan Health System, Ann Arbor, Michigan
| | - Theodore A Kung
- Department of Surgery, Section of Plastic Surgery, University of Michigan Health System, Ann Arbor, Michigan
| | - Paul S Cederna
- Department of Surgery, Section of Plastic Surgery, University of Michigan Health System, Ann Arbor, Michigan.,Department of Biomedical Engineering, Ann Arbor, Michigan
| | - Stephen W P Kemp
- Department of Surgery, Section of Plastic Surgery, University of Michigan Health System, Ann Arbor, Michigan.,Department of Biomedical Engineering, Ann Arbor, Michigan
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Kolesnikova IM, Rumyantsev SA, Volkova NI, Gaponov AM, Grigor’eva TV, Laikov AV, Makarov VV, Yudin SM, Borisenko OV, Shestopalov AV. Influence of Obesity and Its Metabolic Type on the Serum Concentration of Neurotrophins. NEUROCHEM J+ 2022. [DOI: 10.1134/s1819712422020088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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10
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Cintron-Colon AF, Almeida-Alves G, VanGyseghem JM, Spitsbergen JM. GDNF to the rescue: GDNF delivery effects on motor neurons and nerves, and muscle re-innervation after peripheral nerve injuries. Neural Regen Res 2021; 17:748-753. [PMID: 34472460 PMCID: PMC8530131 DOI: 10.4103/1673-5374.322446] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Peripheral nerve injuries commonly occur due to trauma, like a traffic accident. Peripheral nerves get severed, causing motor neuron death and potential muscle atrophy. The current golden standard to treat peripheral nerve lesions, especially lesions with large (≥ 3 cm) nerve gaps, is the use of a nerve autograft or reimplantation in cases where nerve root avulsions occur. If not tended early, degeneration of motor neurons and loss of axon regeneration can occur, leading to loss of function. Although surgical procedures exist, patients often do not fully recover, and quality of life deteriorates. Peripheral nerves have limited regeneration, and it is usually mediated by Schwann cells and neurotrophic factors, like glial cell line-derived neurotrophic factor, as seen in Wallerian degeneration. Glial cell line-derived neurotrophic factor is a neurotrophic factor known to promote motor neuron survival and neurite outgrowth. Glial cell line-derived neurotrophic factor is upregulated in different forms of nerve injuries like axotomy, sciatic nerve crush, and compression, thus creating great interest to explore this protein as a potential treatment for peripheral nerve injuries. Exogenous glial cell line-derived neurotrophic factor has shown positive effects in regeneration and functional recovery when applied in experimental models of peripheral nerve injuries. In this review, we discuss the mechanism of repair provided by Schwann cells and upregulation of glial cell line-derived neurotrophic factor, the latest findings on the effects of glial cell line-derived neurotrophic factor in different types of peripheral nerve injuries, delivery systems, and complementary treatments (electrical muscle stimulation and exercise). Understanding and overcoming the challenges of proper timing and glial cell line-derived neurotrophic factor delivery is paramount to creating novel treatments to tend to peripheral nerve injuries to improve patients’ quality of life.
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Affiliation(s)
| | | | | | - John M Spitsbergen
- Biological Sciences Department, Western Michigan University, Kalamazoo, MI, USA
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11
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GDNF synthesis, signaling, and retrograde transport in motor neurons. Cell Tissue Res 2020; 382:47-56. [PMID: 32897420 PMCID: PMC7529617 DOI: 10.1007/s00441-020-03287-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Accepted: 08/18/2020] [Indexed: 02/06/2023]
Abstract
Glial cell line–derived neurotrophic factor (GDNF) is a 134 amino acid protein belonging in the GDNF family ligands (GFLs). GDNF was originally isolated from rat glial cell lines and identified as a neurotrophic factor with the ability to promote dopamine uptake within midbrain dopaminergic neurons. Since its discovery, the potential neuroprotective effects of GDNF have been researched extensively, and the effect of GDNF on motor neurons will be discussed herein. Similar to other members of the TGF-β superfamily, GDNF is first synthesized as a precursor protein (pro-GDNF). After a series of protein cleavage and processing, the 211 amino acid pro-GDNF is finally converted into the active and mature form of GDNF. GDNF has the ability to trigger receptor tyrosine kinase RET phosphorylation, whose downstream effects have been found to promote neuronal health and survival. The binding of GDNF to its receptors triggers several intracellular signaling pathways which play roles in promoting the development, survival, and maintenance of neuron-neuron and neuron-target tissue interactions. The synthesis and regulation of GDNF have been shown to be altered in many diseases, aging, exercise, and addiction. The neuroprotective effects of GDNF may be used to develop treatments and therapies to ameliorate neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS). In this review, we provide a detailed discussion of the general roles of GDNF and its production, delivery, secretion, and neuroprotective effects on motor neurons within the mammalian neuromuscular system.
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12
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Rink S, Chatziparaskeva C, Elles L, Pavlov S, Nohroudi K, Bendella H, Sarikcioglu L, Manthou M, Dunlop S, Gordon T, Angelov DN. Neutralizing
BDNF
and
FGF2
injection into denervated skeletal muscle improve recovery after nerve repair. Muscle Nerve 2020; 62:404-412. [DOI: 10.1002/mus.26991] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 05/22/2020] [Accepted: 05/30/2020] [Indexed: 12/18/2022]
Affiliation(s)
- Svenja Rink
- Department of Prosthetic Dentistry, School of Dental and Oral MedicineUniversity of Cologne Germany
| | | | - Luisa Elles
- Department of Anatomy IUniversity of Cologne Germany
| | - Stoyan Pavlov
- Department of Anatomy, Histology and EmbryologyMedical University Varna Bulgaria
| | | | - Habib Bendella
- Department of NeurosurgeryUniversity of Witten/Herdecke, Cologne Merheim Medical Center (CMMC) Cologne Germany
| | | | - Marilena Manthou
- Department of Histology and EmbryologyAristotle University Thessaloniki Greece
| | - Sarah Dunlop
- School of Biological SciencesThe University of Western Australia Australia
| | - Tessa Gordon
- Department of SurgeryThe Hospital for Sick Children Toronto Ontario Canada
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13
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Sala-Jarque J, Mesquida-Veny F, Badiola-Mateos M, Samitier J, Hervera A, del Río JA. Neuromuscular Activity Induces Paracrine Signaling and Triggers Axonal Regrowth after Injury in Microfluidic Lab-On-Chip Devices. Cells 2020; 9:cells9020302. [PMID: 32012727 PMCID: PMC7072511 DOI: 10.3390/cells9020302] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/17/2020] [Accepted: 01/23/2020] [Indexed: 12/19/2022] Open
Abstract
Peripheral nerve injuries, including motor neuron axonal injury, often lead to functional impairments. Current therapies are mostly limited to surgical intervention after lesion, yet these interventions have limited success in restoring functionality. Current activity-based therapies after axonal injuries are based on trial-error approaches in which the details of the underlying cellular and molecular processes are largely unknown. Here we show the effects of the modulation of both neuronal and muscular activity with optogenetic approaches to assess the regenerative capacity of cultured motor neuron (MN) after lesion in a compartmentalized microfluidic-assisted axotomy device. With increased neuronal activity, we observed an increase in the ratio of regrowing axons after injury in our peripheral-injury model. Moreover, increasing muscular activity induces the liberation of leukemia inhibitory factor and glial cell line-derived neurotrophic factor in a paracrine fashion that in turn triggers axonal regrowth of lesioned MN in our 3D hydrogel cultures. The relevance of our findings as well as the novel approaches used in this study could be useful not only after axotomy events but also in diseases affecting MN survival.
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Affiliation(s)
- Julia Sala-Jarque
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain; (J.S.-J.); (F.M.-V.); (M.B.-M.); (J.S.)
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
- Department of Cell Biology, Physiology and Immunology, Faculty of Biology, Universitat de Barcelona, 08028 Barcelona, Spain
- Institute of Neuroscience, University of Barcelona, 08028 Barcelona, Spain
| | - Francina Mesquida-Veny
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain; (J.S.-J.); (F.M.-V.); (M.B.-M.); (J.S.)
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
- Department of Cell Biology, Physiology and Immunology, Faculty of Biology, Universitat de Barcelona, 08028 Barcelona, Spain
- Institute of Neuroscience, University of Barcelona, 08028 Barcelona, Spain
| | - Maider Badiola-Mateos
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain; (J.S.-J.); (F.M.-V.); (M.B.-M.); (J.S.)
- Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBERBBN), 28029 Madrid, Spain
- Department of Electronics and Biomedical Engineering, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Josep Samitier
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain; (J.S.-J.); (F.M.-V.); (M.B.-M.); (J.S.)
- Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBERBBN), 28029 Madrid, Spain
- Department of Electronics and Biomedical Engineering, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Arnau Hervera
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain; (J.S.-J.); (F.M.-V.); (M.B.-M.); (J.S.)
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
- Department of Cell Biology, Physiology and Immunology, Faculty of Biology, Universitat de Barcelona, 08028 Barcelona, Spain
- Institute of Neuroscience, University of Barcelona, 08028 Barcelona, Spain
- Correspondence: (A.H.); (J.A.d.R.)
| | - José Antonio del Río
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain; (J.S.-J.); (F.M.-V.); (M.B.-M.); (J.S.)
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
- Department of Cell Biology, Physiology and Immunology, Faculty of Biology, Universitat de Barcelona, 08028 Barcelona, Spain
- Institute of Neuroscience, University of Barcelona, 08028 Barcelona, Spain
- Correspondence: (A.H.); (J.A.d.R.)
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14
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Jia H, Wang Y, Chen J, Li JP, Han HQ, Tong XJ, He ZY, Ma WZ. Combination of BMSCs-laden acellular nerve xenografts transplantation and G-CSF administration promotes sciatic nerve regeneration. Synapse 2019; 73:e22093. [PMID: 30761618 DOI: 10.1002/syn.22093] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/03/2019] [Accepted: 02/11/2019] [Indexed: 12/12/2022]
Abstract
Peripheral nerve gaps often lead to interrupted innervation, manifesting as severe sensory and motor dysfunctions. The repairs of the nerve injuries have not achieved satisfactory curative effects in clinic. The transplantation of bone marrow stromal cells (BMSCs)-laden acellular nerve xenografts (ANX) has been proven more effective than the acellular nerve allografting. Besides, granulocyte colony-stimulating factor (G-CSF) can inhibit inflammation and apoptosis, and thus is conducive to the microenvironmental improvement of axonal regeneration. This study aims to investigate the joint effect of BMSCs-seeded ANX grafting and G-CSF administration, and explore the relevant mechanisms. Adult SD rats were divided into five groups randomly: ANX group, ANX combined with G-CSF group, BMSCs-laden ANX group, BMSCs-laden ANX combined with G-CSF group, and autograft group. Eight weeks after transplantation, the detection of praxiology and neuroelectrophysiology was conducted, and then the morphology of the regenerated nerves was analyzed. The inflammatory response and apoptosis in the nerve grafts as well as the expression of the growth-promoting factors in the regenerated tissues were further assayed. G-CSF intervention and BMSCs implanting synergistically promoted peripheral nerve regeneration and functional recovery following ANX bridging, and the restoration effect was matchable with that of the autologous nerve grafting. Moreover, local inflammation was alleviated, the apoptosis of the seeded BMSCs was decreased, and the levels of the neuromodulatory factors were elevated. In conclusion, the union application of BMSCs-implanted ANX and G-CSF ameliorated the niche of neurotization and advanced nerve regeneration substantially. The strategy achieved the favorable effectiveness as an alternative to the autotransplantation.
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Affiliation(s)
- Hua Jia
- Department of Human Anatomy and Histoembryology, College of Basic Medical Sciences, Ningxia Medical University, Yinchuan, China
| | - Ying Wang
- Research Institute of Neural Tissue Engineering, Department of Anatomy, Mudanjiang College of Medicine, Mudanjiang, China
| | - Jiao Chen
- Department of Human Anatomy and Histoembryology, College of Basic Medical Sciences, Ningxia Medical University, Yinchuan, China
| | - Jun-Ping Li
- Department of Human Anatomy and Histoembryology, College of Basic Medical Sciences, Ningxia Medical University, Yinchuan, China
| | - Huai-Qin Han
- Department of Human Anatomy and Histoembryology, College of Basic Medical Sciences, Ningxia Medical University, Yinchuan, China
| | - Xiao-Jie Tong
- Department of Anatomy, College of Basic Medical Sciences, China Medical University, Shenyang, China
| | - Zhong-Yi He
- Department of Human Anatomy and Histoembryology, College of Basic Medical Sciences, Ningxia Medical University, Yinchuan, China
| | - Wen-Zhi Ma
- Department of Human Anatomy and Histoembryology, College of Basic Medical Sciences, Ningxia Medical University, Yinchuan, China.,Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education, Key Laboratory of Reproduction and Genetics of Ningxia Hui Autonomous Region, Ningxia Medical University, Yinchuan, China
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15
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Halievski K, Nath SR, Katsuno M, Adachi H, Sobue G, Breedlove SM, Lieberman AP, Jordan CL. Disease Affects Bdnf Expression in Synaptic and Extrasynaptic Regions of Skeletal Muscle of Three SBMA Mouse Models. Int J Mol Sci 2019; 20:ijms20061314. [PMID: 30875922 PMCID: PMC6470984 DOI: 10.3390/ijms20061314] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 03/08/2019] [Accepted: 03/09/2019] [Indexed: 01/01/2023] Open
Abstract
Spinal bulbar muscular atrophy (SBMA) is a slowly progressive, androgen-dependent neuromuscular disease in men that is characterized by both muscle and synaptic dysfunction. Because gene expression in muscle is heterogeneous, with synaptic myonuclei expressing genes that regulate synaptic function and extrasynaptic myonuclei expressing genes to regulate contractile function, we used quantitative PCR to compare gene expression in these two domains of muscle from three different mouse models of SBMA: the "97Q" model that ubiquitously expresses mutant human androgen receptor (AR), the 113Q knock-in (KI) model that expresses humanized mouse AR with an expanded glutamine tract, and the "myogenic" model that overexpresses wild-type rat AR only in skeletal muscle. We were particularly interested in neurotrophic factors because of their role in maintaining neuromuscular function via effects on both muscle and synaptic function, and their implicated role in SBMA. We confirmed previous reports of the enriched expression of select genes (e.g., the acetylcholine receptor) in the synaptic region of muscle, and are the first to report the synaptic enrichment of others (e.g., glial cell line-derived neurotrophic factor). Interestingly, all three models displayed comparably dysregulated expression of most genes examined in both the synaptic and extrasynaptic domains of muscle, with only modest differences between regions and models. These findings of comprehensive gene dysregulation in muscle support the emerging view that skeletal muscle may be a prime therapeutic target for restoring function of both muscles and motoneurons in SBMA.
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Affiliation(s)
- Katherine Halievski
- Neuroscience Program, 108 Giltner Hall, Michigan State University, East Lansing, MI 48824-1115, USA.
| | - Samir R Nath
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
| | - Masahisa Katsuno
- Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
| | - Hiroaki Adachi
- Department of Neurology, University of Occupational and Environment Health School of Medicine, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu Fukuoka 807-8555, Japan.
| | - Gen Sobue
- Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
| | - S Marc Breedlove
- Neuroscience Program, 108 Giltner Hall, Michigan State University, East Lansing, MI 48824-1115, USA.
| | - Andrew P Lieberman
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
| | - Cynthia L Jordan
- Neuroscience Program, 108 Giltner Hall, Michigan State University, East Lansing, MI 48824-1115, USA.
- Physiology Department, 108 Giltner Hall, Michigan State University, East Lansing, MI 48824-1115, USA.
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16
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Kang H, Tian L, Thompson WJ. Schwann cell guidance of nerve growth between synaptic sites explains changes in the pattern of muscle innervation and remodeling of synaptic sites following peripheral nerve injuries. J Comp Neurol 2019; 527:1388-1400. [PMID: 30620049 DOI: 10.1002/cne.24625] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 12/17/2018] [Accepted: 12/20/2018] [Indexed: 01/14/2023]
Abstract
Terminal Schwann cells (SCs) are nonmyelinating glia that are a prominent component of the neuromuscular junction (NMJ) where motor neurons form synapses onto muscle fibers. These cells play important roles not only in development and maintenance of the neuromuscular synapse but also restoring synaptic function after nerve damage. In response to muscle denervation, terminal SCs undergo dramatic changes in their gene expression patterns as well as in their morphology, such as extending elaborate processes into inter-junctional space. These SC processes serve as a path to guide axon terminal sprouts from nearby innervated junctions, promoting rapid reinnervation of denervated fibers. We studied the role of terminal SCs in synapse reformation by using two different fluorescent proteins to simultaneously label motor axons and SCs; we examined these junctions repeatedly in living animals using a fluorescence microscope. Here, we show that alterations in the patterns of muscle innervation following recovery from nerve injury can be explained by SC guidance of regenerating axons. In turn, this guidance leads to remodeling of the NMJ itself.
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Affiliation(s)
- Hyuno Kang
- Section of Molecular Cell and Developmental Biology, The University of Texas at Austin, Austin, Texas.,Gwangju Center, Korea Basic Science Institute, Gwangju, South Korea
| | - Le Tian
- Section of Molecular Cell and Developmental Biology, The University of Texas at Austin, Austin, Texas
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17
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Shanmukha S, Narayanappa G, Nalini A, Alladi PA, Raju TR. Sporadic amyotrophic lateral sclerosis (SALS) - skeletal muscle response to cerebrospinal fluid from SALS patients in a rat model. Dis Model Mech 2018; 11:11/4/dmm031997. [PMID: 29666144 PMCID: PMC5963857 DOI: 10.1242/dmm.031997] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 03/05/2018] [Indexed: 01/17/2023] Open
Abstract
Skeletal muscle atrophy is the most prominent feature of amyotrophic lateral sclerosis (ALS), an adult-onset neurodegenerative disease of motor neurons. However, the contribution of skeletal muscle to disease progression remains elusive. Our previous studies have shown that intrathecal injection of cerebrospinal fluid from sporadic ALS patients (ALS-CSF) induces several degenerative changes in motor neurons and glia of neonatal rats. Here, we describe various pathologic events in the rat extensor digitorum longus muscle following intrathecal injection of ALS-CSF. Adenosine triphosphatase staining and electron microscopic (EM) analysis revealed significant atrophy and grouping of type 2 fibres in ALS-CSF-injected rats. Profound neuromuscular junction (NMJ) damage, such as fragmentation accompanied by denervation, were revealed by α-bungarotoxin immunostaining. Altered expression of key NMJ proteins, rapsyn and calpain, was also observed by immunoblotting. In addition, EM analysis showed sarcolemmal folding, Z-line streaming, structural alterations of mitochondria and dilated sarcoplasmic reticulum. The expression of trophic factors was affected, with significant downregulation of vascular endothelial growth factor (VEGF), marginal reduction in insulin-like growth factor-1 (IGF-1), and upregulation of brain-derived neurotrophic factor (BDNF) and glial-derived neurotrophic factor (GDNF). However, motor neurons might be unable to harness the enhanced levels of BDNF and GDNF, owing to impaired NMJs. We propose that ALS-CSF triggers motor neuronal degeneration, resulting in pathological changes in the skeletal muscle. Muscle damage further aggravates the motor neuronal pathology, because of the interdependency between them. This sets in a vicious cycle, leading to rapid and progressive loss of motor neurons, which could explain the relentless course of ALS.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Shruthi Shanmukha
- Department of Neurophysiology, National Institute of Mental Health and Neurosciences, Hosur Road, Bangalore 560 029, India
| | - Gayathri Narayanappa
- Department of Neuropathology, National Institute of Mental Health and Neurosciences, Hosur Road, Bangalore 560 029, India
| | - Atchayaram Nalini
- Department of Neurology, National Institute of Mental Health and Neurosciences, Hosur Road, Bangalore 560 029, India
| | - Phalguni Anand Alladi
- Department of Neurophysiology, National Institute of Mental Health and Neurosciences, Hosur Road, Bangalore 560 029, India
| | - Trichur R Raju
- Department of Neurophysiology, National Institute of Mental Health and Neurosciences, Hosur Road, Bangalore 560 029, India
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18
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Rosko AJ, Kupfer RA, Oh SS, Haring CT, Feldman EL, Hogikyan ND. Immunohistologic analysis of spontaneous recurrent laryngeal nerve reinnervation in a rat model. Laryngoscope 2017; 128:E117-E122. [DOI: 10.1002/lary.27004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/16/2017] [Indexed: 01/29/2023]
Affiliation(s)
- Andrew J. Rosko
- Department of Otolaryngology-Head and Neck Surgery; University of Michigan Health Center; Ann Arbor Michigan U.S.A
| | - Robbi A. Kupfer
- Department of Otolaryngology-Head and Neck Surgery; University of Michigan Health Center; Ann Arbor Michigan U.S.A
| | - Sang S. Oh
- Department of Neurology; University of Michigan Medical School; Ann Arbor Michigan U.S.A
| | - Catherine T. Haring
- Department of Otolaryngology-Head and Neck Surgery; University of Michigan Health Center; Ann Arbor Michigan U.S.A
| | - Eva L. Feldman
- Department of Neurology; University of Michigan Medical School; Ann Arbor Michigan U.S.A
| | - Norman D. Hogikyan
- Department of Otolaryngology-Head and Neck Surgery; University of Michigan Health Center; Ann Arbor Michigan U.S.A
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19
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Bendella H, Rink S, Grosheva M, Sarikcioglu L, Gordon T, Angelov DN. Putative roles of soluble trophic factors in facial nerve regeneration, target reinnervation, and recovery of vibrissal whisking. Exp Neurol 2017; 300:100-110. [PMID: 29104116 DOI: 10.1016/j.expneurol.2017.10.029] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 10/25/2017] [Accepted: 10/30/2017] [Indexed: 12/15/2022]
Abstract
It is well-known that, after nerve transection and surgical repair, misdirected regrowth of regenerating motor axons may occur in three ways. The first way is that the axons enter into endoneurial tubes that they did not previously occupy, regenerate through incorrect fascicles and reinnervate muscles that they did not formerly supply. Consequently the activation of these muscles results in inappropriate movements. The second way is that, in contrast with the precise target-directed pathfinding by elongating motor nerves during embryonic development, several axons rather than a single axon grow out from each transected nerve fiber. The third way of misdirection occurs by the intramuscular terminal branching (sprouting) of each regenerating axon to culminate in some polyinnervation of neuromuscular junctions, i.e. reinnervation of junctions by more than a single axon. Presently, "fascicular" or "topographic specificity" cannot be achieved and hence target-directed nerve regeneration is, as yet, unattainable. Nonetheless, motor and sensory reinnervation of appropriate endoneurial tubes does occur and can be promoted by brief nerve electrical stimulation. This review considers the expression of neurotrophic factors in the neuromuscular system and how this expression can promote functional recovery, with emphasis on the whisking of vibrissae on the rat face in relationship to the expression of the factors. Evidence is reviewed for a role of neurotrophic factors as short-range diffusible sprouting stimuli in promoting complete functional recovery of vibrissal whisking in blind Sprague Dawley (SD)/RCS rats but not in SD rats with normal vision, after facial nerve transection and surgical repair. Briefly, a complicated time course of growth factor expression in the nerves and denervated muscles include (1) an early increase in FGF2 and IGF2, (2) reduced NGF between 2 and 14days after nerve transection and surgical repair, (3) a late rise in BDNF and (4) reduced IGF1 protein in the denervated muscles at 28days. These findings suggest that recovery of motor function after peripheral nerve injury is due, at least in part, to a complex regulation of nerve injury-associated neurotrophic factors and cytokines at the neuromuscular junctions of denervated muscles. In particular, the increase of FGF2 and concomittant decrease of NGF during the first week after facial nerve-nerve anastomosis in SD/RCS blind rats may prevent intramuscular axon sprouting and, in turn, reduce poly-innervation of the neuromuscular junction.
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Affiliation(s)
- Habib Bendella
- Department of Neurosurgery, University of Witten/Herdecke, Cologne Merheim Medical Center (CMMC), Cologne, Germany
| | - Svenja Rink
- Department of Prosthetic Dentistry, School of Dental and Oral Medicine, University of Cologne, Germany
| | - Maria Grosheva
- Department of Oto-Rhino-Laryngology, University of Cologne, Germany
| | | | - Tessa Gordon
- Department of Surgery, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
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20
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Aare S, Spendiff S, Vuda M, Elkrief D, Perez A, Wu Q, Mayaki D, Hussain SNA, Hettwer S, Hepple RT. Failed reinnervation in aging skeletal muscle. Skelet Muscle 2016; 6:29. [PMID: 27588166 PMCID: PMC5007704 DOI: 10.1186/s13395-016-0101-y] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 08/05/2016] [Indexed: 12/08/2023] Open
Abstract
BACKGROUND Skeletal muscle displays a marked accumulation of denervated myofibers at advanced age, which coincides with an acceleration of muscle atrophy. METHODS In this study, we evaluated the hypothesis that the accumulation of denervated myofibers in advanced age is due to failed reinnervation by examining muscle from young adult (YA) and very old (VO) rats and from a murine model of sporadic denervation secondary to neurotrypsin over-expression (Sarco mouse). RESULTS Both aging rat muscle and Sarco mouse muscle exhibited marked fiber-type grouping, consistent with repeating cycles of denervation and reinnervation, yet in VO muscle, rapsyn at the endplate increased and was associated with only a 10 % decline in acetylcholine receptor (AChR) intensity, whereas in Sarco mice, there was a decline in rapsyn and a 25 % decrease in AChR intensity. Transcripts of muscle-specific kinase (21-fold), acetylcholine receptor subunits α (68-fold), ε (threefold) and γ (47-fold), neural cell adhesion molecule (66-fold), and runt-related transcription factor 1 (33-fold) were upregulated in VO muscle of the rat, consistent with the marked persistent denervation evidenced by a large proportion of very small fibers (>20 %). In the Sarco mice, there were much smaller increases in denervation transcripts (0-3.5-fold) and accumulation of very small fibers (2-6 %) compared to the VO rat, suggesting a reduced capacity for reinnervation in aging muscle. Despite the marked persistent denervation in the VO rat muscle, transcripts of neurotrophins involved in promoting axonal sprouting following denervation exhibited no increase, and several miRNAs predicted to suppress neurotrophins were elevated in VO rat. CONCLUSIONS Our results support the hypothesis that the accumulation of denervated fibers with aging is due to failed reinnervation and that this may be affected by a limited neurotrophin response that mediates axonal sprouting following denervation.
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Affiliation(s)
- Sudhakar Aare
- Research Institute of the McGill University Health Centre, EM2.2232, RI MUHC, 1001 Decarie Blvd, Montreal, QC Canada H4A 3J1 ; McGill Research Centre for Physical Activity and Health, McGill University, Montreal, QC Canada
| | - Sally Spendiff
- Research Institute of the McGill University Health Centre, EM2.2232, RI MUHC, 1001 Decarie Blvd, Montreal, QC Canada H4A 3J1 ; McGill Research Centre for Physical Activity and Health, McGill University, Montreal, QC Canada
| | - Madhusudanarao Vuda
- Research Institute of the McGill University Health Centre, EM2.2232, RI MUHC, 1001 Decarie Blvd, Montreal, QC Canada H4A 3J1 ; McGill Research Centre for Physical Activity and Health, McGill University, Montreal, QC Canada
| | - Daren Elkrief
- Research Institute of the McGill University Health Centre, EM2.2232, RI MUHC, 1001 Decarie Blvd, Montreal, QC Canada H4A 3J1 ; McGill Research Centre for Physical Activity and Health, McGill University, Montreal, QC Canada ; Department of Kinesiology and Physical Education, McGill University, Montreal, QC Canada
| | - Anna Perez
- Research Institute of the McGill University Health Centre, EM2.2232, RI MUHC, 1001 Decarie Blvd, Montreal, QC Canada H4A 3J1
| | - Qinghua Wu
- Research Institute of the McGill University Health Centre, EM2.2232, RI MUHC, 1001 Decarie Blvd, Montreal, QC Canada H4A 3J1 ; McGill Research Centre for Physical Activity and Health, McGill University, Montreal, QC Canada
| | - Dominique Mayaki
- Research Institute of the McGill University Health Centre, EM2.2232, RI MUHC, 1001 Decarie Blvd, Montreal, QC Canada H4A 3J1
| | - Sabah N A Hussain
- Research Institute of the McGill University Health Centre, EM2.2232, RI MUHC, 1001 Decarie Blvd, Montreal, QC Canada H4A 3J1
| | | | - Russell T Hepple
- Research Institute of the McGill University Health Centre, EM2.2232, RI MUHC, 1001 Decarie Blvd, Montreal, QC Canada H4A 3J1 ; McGill Research Centre for Physical Activity and Health, McGill University, Montreal, QC Canada ; Department of Kinesiology and Physical Education, McGill University, Montreal, QC Canada
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21
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Willand MP, Rosa E, Michalski B, Zhang JJ, Gordon T, Fahnestock M, Borschel GH. Electrical muscle stimulation elevates intramuscular BDNF and GDNF mRNA following peripheral nerve injury and repair in rats. Neuroscience 2016; 334:93-104. [PMID: 27476437 DOI: 10.1016/j.neuroscience.2016.07.040] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 07/21/2016] [Accepted: 07/23/2016] [Indexed: 10/21/2022]
Abstract
Despite advances in surgery, patients with nerve injuries frequently have functional deficits. We previously demonstrated in a rat model that daily electrical muscle stimulation (EMS) following peripheral nerve injury and repair enhances reinnervation, detectable as early as two weeks post-injury. In this study, we explain the enhanced early reinnervation observed with electrical stimulation. In two groups of rats, the tibial nerve was transected and immediately repaired. Gastrocnemius muscles were implanted with intramuscular electrodes for sham or muscle stimulation. Muscles were stimulated daily, eliciting 600 contractions for one hour/day, repeated five days per week. Sixteen days following nerve injury, muscles were assessed for functional reinnervation by motor unit number estimation methods using electromyographic recording. In a separate cohort of rats, surgical and electrical stimulation procedures were identical but muscles and distal nerve stumps were harvested for molecular analysis. We observed that stimulated muscles had significantly higher motor unit number counts. Intramuscular levels of brain-derived and glial cell line-derived neurotrophic factor (BDNF and GDNF) mRNA were significantly upregulated in muscles that underwent daily electrical stimulation compared to those without stimulation. The corresponding levels of trophic factor mRNA within the distal stump were not different from one another, indicating that the intramuscular electrical stimulus does not modulate Schwann cell-derived trophic factor transcription. Stimulation over a three-month period maintained elevated muscle-derived GDNF but not BDNF mRNA. In conclusion, EMS elevates intramuscular trophic factor mRNA levels which may explain how EMS enhances neural regeneration following nerve injury.
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Affiliation(s)
- Michael P Willand
- Department of Surgery, Division of Plastic Reconstructive Surgery, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada.
| | - Elyse Rosa
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Bernadeta Michalski
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Jennifer J Zhang
- Department of Surgery, Division of Plastic Reconstructive Surgery, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; SickKids Research Institute Program in Neuroscience and Mental Health, Toronto, ON, Canada
| | - Tessa Gordon
- Department of Surgery, Division of Plastic Reconstructive Surgery, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Margaret Fahnestock
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Gregory H Borschel
- Department of Surgery, Division of Plastic Reconstructive Surgery, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada; SickKids Research Institute Program in Neuroscience and Mental Health, Toronto, ON, Canada; University of Toronto Division of Plastic and Reconstructive Surgery, Toronto, ON, Canada
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22
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Hendry JM, Alvarez-Veronesi MC, Snyder-Warwick A, Gordon T, Borschel GH. Side-To-Side Nerve Bridges Support Donor Axon Regeneration Into Chronically Denervated Nerves and Are Associated With Characteristic Changes in Schwann Cell Phenotype. Neurosurgery 2016; 77:803-13. [PMID: 26171579 DOI: 10.1227/neu.0000000000000898] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Chronic denervation resulting from long nerve regeneration times and distances contributes greatly to suboptimal outcomes following nerve injuries. Recent studies showed that multiple nerve grafts inserted between an intact donor nerve and a denervated distal recipient nerve stump (termed "side-to-side nerve bridges") enhanced regeneration after delayed nerve repair. OBJECTIVE To examine the cellular aspects of axon growth across these bridges to explore the "protective" mechanism of donor axons on chronically denervated Schwann cells. METHODS In Sprague Dawley rats, 3 side-to-side nerve bridges were placed over a 10-mm distance between an intact donor tibial (TIB) nerve and a recipient denervated common peroneal (CP) distal nerve stump. Green fluorescent protein-expressing TIB axons grew across the bridges and were counted in cross section after 4 weeks. Immunofluorescent axons and Schwann cells were imaged over a 4-month period. RESULTS Denervated Schwann cells dedifferentiated to a proliferative, nonmyelinating phenotype within the bridges and the recipient denervated CP nerve stump. As donor TIB axons grew across the 3 side-to-side nerve bridges and into the denervated CP nerve, the Schwann cells redifferentiated to the myelinating phenotype. Bridge placement led to an increased mass of hind limb anterior compartment muscles after 4 months of denervation compared with muscles whose CP nerve was not "protected" by bridges. CONCLUSION This study describes patterns of donor axon regeneration and myelination in the denervated recipient nerve stump and supports a mechanism where these donor axons sustain a proregenerative state to prevent deterioration in the face of chronic denervation.
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Affiliation(s)
- J Michael Hendry
- *Division of Plastic and Reconstructive Surgery, The Hospital for Sick Children, Toronto, ON, Canada; ‡Department of Surgery, §Institute of Medical Science, and ¶Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada; ‖SickKids Research Institute Program in Neuroscience, Toronto, ON, Canada
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Hizay A, Seitz M, Grosheva M, Sinis N, Kaya Y, Bendella H, Sarikcioglu L, Dunlop SA, Angelov DN. FGF-2 is required to prevent astrogliosis in the facial nucleus after facial nerve injury and mechanical stimulation of denervated vibrissal muscles. J Biomed Res 2016; 30:142-148. [PMID: 28276669 PMCID: PMC4820891 DOI: 10.7555/jbr.30.20140042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 11/28/2014] [Accepted: 04/10/2015] [Indexed: 01/20/2023] Open
Abstract
Recently, we have shown that manual stimulation of paralyzed vibrissal muscles after facial-facial anastomosis reduced the poly-innervation of neuromuscular junctions and restored vibrissal whisking. Using gene knock outs, we found a differential dependence of manual stimulation effects on growth factors. Thus, insulin-like growth factor-1 and brain-derived neurotrophic factor are required to underpin manual stimulation-mediated improvements, whereas FGF-2 is not. The lack of dependence on FGF-2 in mediating these peripheral effects prompted us to look centrally, i.e. within the facial nucleus where increased astrogliosis after facial-facial anastomosis follows "synaptic stripping". We measured the intensity of Cy3-fluorescence after immunostaining for glial fibrillary acidic protein (GFAP) as an indirect indicator of synaptic coverage of axotomized neurons in the facial nucleus of mice lacking FGF-2 (FGF-2-/- mice). There was no difference in GFAP-Cy3-fluorescence (pixel number, gray value range 17–103) between intact wildtype mice (2.12± 0.37×107) and their intact FGF-2-/- counterparts (2.12± 0.27×107) nor after facial-facial anastomosis +handling (wildtype: 4.06± 0.32×107; FGF-2-/-: 4.39±0.17×107). However, after facial-facial anastomosis, GFAP-Cy3-fluorescence remained elevated in FGF-2-/--animals (4.54±0.12×107), whereas manual stimulation reduced the intensity of GFAP-immunofluorescence in wild type mice to values that were not significantly different from intact mice (2.63± 0.39×10 ). We conclude that FGF-2 is not required to underpin the beneficial effects of manual stimulation at the neuro-muscular junction, but it is required to minimize astrogliosis in the brainstem and, by implication, restore synaptic coverage of recovering facial motoneurons.
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Affiliation(s)
- Arzu Hizay
- Department of Anatomy, Akdeniz University, Faculty of Medicine, Dumlupinar Bulvari 07058 Kampus, Antalya, Turkey
| | - Mark Seitz
- Department of Anatomy I, University of Cologne, Joseph-Stelzmann-Strasse 9, D-50924 Cologne, FR Germany
| | - Maria Grosheva
- Department of Oto-Rhino-Laryngology, University Hospital Cologne, Joseph-Stelzmann-Strasse 9, D-50924 Cologne, FR Germany
| | - Nektarios Sinis
- Depeartment of Plastic-, Hand- and Reconstructive Microsurgery, Berlin, FR 12249, Germany
| | - Yasemin Kaya
- Department of Anatomy, Akdeniz University, Faculty of Medicine, Dumlupinar Bulvari 07058 Kampus, Antalya, Turkey
| | - Habib Bendella
- Department of Neurosurgery, Hospital Merheim, University of Witten-Herdecke, Ostmerheimer Straße 200, 51109 Cologne, Germany
| | - Levent Sarikcioglu
- Department of Anatomy, Akdeniz University, Faculty of Medicine, Dumlupinar Bulvari 07058 Kampus, Antalya, Turkey
| | - Sarah A Dunlop
- Experimental and Regenerative Neurosciences, School of Animal Biology, University of Western Australia (M092) 35 Stirling Highway, CRAWLEY WA 6009, Australia
| | - Doychin N Angelov
- Department of Anatomy I, University of Cologne, Joseph-Stelzmann-Strasse 9, D-50924 Cologne, FR Germany;
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Grosheva M, Nohroudi K, Schwarz A, Rink S, Bendella H, Sarikcioglu L, Klimaschewski L, Gordon T, Angelov DN. Comparison of trophic factors' expression between paralyzed and recovering muscles after facial nerve injury. A quantitative analysis in time course. Exp Neurol 2016; 279:137-148. [PMID: 26940083 DOI: 10.1016/j.expneurol.2016.02.020] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Revised: 02/07/2016] [Accepted: 02/26/2016] [Indexed: 01/08/2023]
Abstract
After peripheral nerve injury, recovery of motor performance negatively correlates with the poly-innervation of neuromuscular junctions (NMJ) due to excessive sprouting of the terminal Schwann cells. Denervated muscles produce short-range diffusible sprouting stimuli, of which some are neurotrophic factors. Based on recent data that vibrissal whisking is restored perfectly during facial nerve regeneration in blind rats from the Sprague Dawley (SD)/RCS strain, we compared the expression of brain derived neurotrophic factor (BDNF), fibroblast growth factor-2 (FGF2), insulin growth factors 1 and 2 (IGF1, IGF2) and nerve growth factor (NGF) between SD/RCS and SD-rats with normal vision but poor recovery of whisking function after facial nerve injury. To establish which trophic factors might be responsible for proper NMJ-reinnervation, the transected facial nerve was surgically repaired (facial-facial anastomosis, FFA) for subsequent analysis of mRNA and proteins expressed in the levator labii superioris muscle. A complicated time course of expression included (1) a late rise in BDNF protein that followed earlier elevated gene expression, (2) an early increase in FGF2 and IGF2 protein after 2 days with sustained gene expression, (3) reduced IGF1 protein at 28 days coincident with decline of raised mRNA levels to baseline, and (4) reduced NGF protein between 2 and 14 days with maintained gene expression found in blind rats but not the rats with normal vision. These findings suggest that recovery of motor function after peripheral nerve injury is due, at least in part, to a complex regulation of lesion-associated neurotrophic factors and cytokines in denervated muscles. The increase of FGF-2 protein and concomittant decrease of NGF (with no significant changes in BDNF or IGF levels) during the first week following FFA in SD/RCS blind rats possibly prevents the distal branching of regenerating axons resulting in reduced poly-innervation of motor endplates.
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Affiliation(s)
- Maria Grosheva
- Department of Oto-Rhino-Laryngology, University of Cologne, Germany
| | | | - Alisa Schwarz
- Department of Anatomy I, University of Cologne, Germany
| | - Svenja Rink
- Department of Anatomy I, University of Cologne, Germany
| | - Habib Bendella
- Department of Neurosurgery, Hospital Merheim, University of Witten-Herdecke, Cologne, Germany
| | | | - Lars Klimaschewski
- Division of Neuroanatomy Innsbruck Medical University, 6020 Innsbruck, Austria
| | - Tessa Gordon
- Department of Surgery,The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
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25
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Madhu V, Dighe AS, Cui Q, Deal DN. Dual Inhibition of Activin/Nodal/TGF-β and BMP Signaling Pathways by SB431542 and Dorsomorphin Induces Neuronal Differentiation of Human Adipose Derived Stem Cells. Stem Cells Int 2015; 2016:1035374. [PMID: 26798350 PMCID: PMC4699250 DOI: 10.1155/2016/1035374] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 09/03/2015] [Indexed: 12/16/2022] Open
Abstract
Damage to the nervous system can cause devastating diseases or musculoskeletal dysfunctions and transplantation of progenitor stem cells can be an excellent treatment option in this regard. Preclinical studies demonstrate that untreated stem cells, unlike stem cells activated to differentiate into neuronal lineage, do not survive in the neuronal tissues. Conventional methods of inducing neuronal differentiation of stem cells are complex and expensive. We therefore sought to determine if a simple, one-step, and cost effective method, previously reported to induce neuronal differentiation of embryonic stem cells and induced-pluripotent stem cells, can be applied to adult stem cells. Indeed, dual inhibition of activin/nodal/TGF-β and BMP pathways using SB431542 and dorsomorphin, respectively, induced neuronal differentiation of human adipose derived stem cells (hADSCs) as evidenced by formation of neurite extensions, protein expression of neuron-specific gamma enolase, and mRNA expression of neuron-specific transcription factors Sox1 and Pax6 and matured neuronal marker NF200. This process correlated with enhanced phosphorylation of p38, Erk1/2, PI3K, and Akt1/3. Additionally, in vitro subcutaneous implants of SB431542 and dorsomorphin treated hADSCs displayed significantly higher expression of active-axonal-growth-specific marker GAP43. Our data offers novel insights into cell-based therapies for the nervous system repair.
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Affiliation(s)
- Vedavathi Madhu
- Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA 22908, USA
| | - Abhijit S. Dighe
- Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA 22908, USA
| | - Quanjun Cui
- Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA 22908, USA
| | - D. Nicole Deal
- Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA 22908, USA
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26
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Cisterna BA, Cardozo C, Sáez JC. Neuronal involvement in muscular atrophy. Front Cell Neurosci 2014; 8:405. [PMID: 25540609 PMCID: PMC4261799 DOI: 10.3389/fncel.2014.00405] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 11/10/2014] [Indexed: 12/18/2022] Open
Abstract
The innervation of skeletal myofibers exerts a crucial influence on the maintenance of muscle tone and normal operation. Consequently, denervated myofibers manifest atrophy, which is preceded by an increase in sarcolemma permeability. Recently, de novo expression of hemichannels (HCs) formed by connexins (Cxs) and other none selective channels, including P2X7 receptors (P2X7Rs), and transient receptor potential, sub-family V, member 2 (TRPV2) channels was demonstrated in denervated fast skeletal muscles. The denervation-induced atrophy was drastically reduced in denervated muscles deficient in Cxs 43 and 45. Nonetheless, the transduction mechanism by which the nerve represses the expression of the above mentioned non-selective channels remains unknown. The paracrine action of extracellular signaling molecules including ATP, neurotrophic factors (i.e., brain-derived neurotrophic factor (BDNF)), agrin/LDL receptor-related protein 4 (Lrp4)/muscle-specific receptor kinase (MuSK) and acetylcholine (Ach) are among the possible signals for repression for connexin expression. This review discusses the possible role of relevant factors in maintaining the normal functioning of fast skeletal muscles and suppression of connexin hemichannel expression.
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Affiliation(s)
- Bruno A. Cisterna
- Departamento de Fisiología, Pontificia Universidad Católica de ChileSantiago, Chile
| | - Christopher Cardozo
- Center of Excellence for the Medical Consequences of Spinal Cord Injury, James J. Peters Veterans Affairs Medical CenterBronx, NY, USA
- Departments of Medicine and Rehabilitation Medicine, Icahn School of Medicine at Mount SinaiNew York, NY, USA
| | - Juan C. Sáez
- Departamento de Fisiología, Pontificia Universidad Católica de ChileSantiago, Chile
- Instituto Milenio, Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de ValparaísoValparaíso, Chile
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Wu P, Chawla A, Spinner RJ, Yu C, Yaszemski MJ, Windebank AJ, Wang H. Key changes in denervated muscles and their impact on regeneration and reinnervation. Neural Regen Res 2014; 9:1796-809. [PMID: 25422641 PMCID: PMC4239769 DOI: 10.4103/1673-5374.143424] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/11/2014] [Indexed: 11/29/2022] Open
Abstract
The neuromuscular junction becomes progressively less receptive to regenerating axons if nerve repair is delayed for a long period of time. It is difficult to ascertain the denervated muscle's residual receptivity by time alone. Other sensitive markers that closely correlate with the extent of denervation should be found. After a denervated muscle develops a fibrillation potential, muscle fiber conduction velocity, muscle fiber diameter, muscle wet weight, and maximal isometric force all decrease; remodeling increases neuromuscular junction fragmentation and plantar area, and expression of myogenesis-related genes is initially up-regulated and then down-regulated. All these changes correlate with both the time course and degree of denervation. The nature and time course of these denervation changes in muscle are reviewed from the literature to explore their roles in assessing both the degree of detrimental changes and the potential success of a nerve repair. Fibrillation potential amplitude, muscle fiber conduction velocity, muscle fiber diameter, mRNA expression levels of myogenic regulatory factors and nicotinic acetylcholine receptor could all reflect the severity and length of denervation and the receptiveness of denervated muscle to regenerating axons, which could possibly offer an important clue for surgical choices and predict the outcomes of delayed nerve repair.
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Affiliation(s)
- Peng Wu
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA ; Department of Hand Surgery, Huashan Hospital, Fudan University, Shanghai, China ; Department of Orthopedic Surgery, the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, China
| | - Aditya Chawla
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA ; Department of Orthopedic Surgery, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Robert J Spinner
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA
| | - Cong Yu
- Department of Hand Surgery, Huashan Hospital, Fudan University, Shanghai, China
| | - Michael J Yaszemski
- Departments of Orthopedic Surgery and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
| | | | - Huan Wang
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA ; Shanghai Key Laboratory of Peripheral Nerve and Microsurgery, Shanghai, China
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Rosa E, Cha J, Bain JR, Fahnestock M. Calcitonin gene-related peptide regulation of glial cell-line derived neurotrophic factor in differentiated rat myotubes. J Neurosci Res 2014; 93:514-20. [PMID: 25403360 DOI: 10.1002/jnr.23512] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 09/29/2014] [Accepted: 10/09/2014] [Indexed: 01/05/2023]
Abstract
Glial cell-line derived neurotrophic factor (GDNF) is the most potent trophic factor for motoneuron survival and neuromuscular junction formation. GDNF is upregulated in injured or denervated skeletal muscle and returns to normal levels following reinnervation. However, the mechanism by which GDNF is regulated in denervated muscle is not well understood. The nerve-derived neurotransmitter calcitonin gene-related peptide (CGRP) is upregulated following neuromuscular injury and is subsequently released from motoneurons at the neuromuscular junction. CGRP also promotes nerve regeneration, but the mechanism is not well understood. The current study investigates whether this increase in CGRP regulates GDNF, thus playing a key role in promoting regeneration of injured nerves. This study demonstrates that CGRP increases GDNF secretion without affecting its transcription or translation. Rat L6 myoblasts were differentiated into myotubes and subsequently treated with CGRP. GDNF mRNA expression levels were quantified by quantitative real-time reverse transcription-polymerase chain reaction, and secreted GDNF was quantified in the conditioned medium by ELISA. CGRP treatment increased secreted GDNF protein without altering GDNF mRNA levels. The translational inhibitor cycloheximide did not affect CGRP-induced GDNF secreted protein levels, whereas the secretional inhibitor brefeldin A blocked the CGRP-induced increase in GDNF. This study highlights the importance of injury-induced upregulation of CGRP by exposing its ability to increase GDNF levels and demonstrates a secretional mechanism for regulation of this key regeneration-promoting neurotrophic factor.
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Affiliation(s)
- Elyse Rosa
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, Ontario, Canada
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29
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Sensoric protection after median nerve injury: babysitter-procedure prevents muscular atrophy and improves neuronal recovery. BIOMED RESEARCH INTERNATIONAL 2014; 2014:724197. [PMID: 25133176 PMCID: PMC4123520 DOI: 10.1155/2014/724197] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 06/05/2014] [Accepted: 06/10/2014] [Indexed: 11/17/2022]
Abstract
The babysitter-procedure might offer an alternative when nerve reconstruction is delayed in order to overcome muscular atrophy due to denervation. In this study we aimed to show that a sensomotoric babysitter-procedure after median nerve injury is capable of preserving irreversible muscular atrophy. The median nerve of 20 female Wistar rats was denervated. 10 animals received a sensory protection with the N. cutaneous brachii. After six weeks the median nerve was reconstructed by autologous nerve grafting from the contralateral median nerve in the babysitter and the control groups. Grasping tests measured functional recovery over 15 weeks. At the end of the observation period the weight of the flexor digitorum sublimis muscle was determined. The median nerve was excised for histological examinations. Muscle weight (P < 0.0001) was significantly superior in the babysitter group compared to the control group at the end of the study. The histological evaluation revealed a significantly higher diameter of axons (P = 0.0194), nerve fiber (P = 0.0409), and nerve surface (P = 0.0184) in the babysitter group. We conclude that sensory protection of a motor nerve is capable of preserving muscule weight and we may presume that metabolism of the sensory nerve was sufficient to keep the target muscle's weight and vitality.
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30
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Li Q, Zhang P, Yin X, Han N, Kou Y, Jiang B. Early sensory protection in reverse end-to-side neurorrhaphy to improve the functional recovery of chronically denervated muscle in rat: a pilot study. J Neurosurg 2014; 121:415-22. [PMID: 24878291 DOI: 10.3171/2014.4.jns131723] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECT Early innervation by sensory nerves has been proposed to prevent atrophy of chronically denervated muscle, but conventional end-to-end (ETE) neurorrhaphy has been demonstrated to have adverse effects on muscle contractile function. The aim of the present study was to investigate the potential for modified sensory nerve protection in reverse end-to-side (ETS) neurorrhaphy as a way of improving the functional recovery of denervated muscle. METHODS Four groups of rats underwent surgical denervation of the tibial nerve projecting to the right hindlimbs (Group 1, unprotected controls; Group 2, positive control [immediate repair without delayed denervation]; Group 3, ETS protected; and Group 4, ETE protected). The proximal and distal stumps of the tibial nerve were ligated in all animals except for those in the immediate-repair group. Other animals underwent denervation without sural nerve protection, or with ETE or ETS neurorrhaphy. The ETE- and ETS-protected and unprotected groups underwent an additional surgery in which the trimmed proximal and distal tibial nerve stumps were sutured together. After 3 months of recovery, the tibial function index was determined, and electrophysiological, histological, and morphometric parameters were assessed. RESULTS Significant muscle atrophy was observed in the unprotected group, while a well-preserved ultrastructure was observed for the gastrocnemius muscle in the ETE- and ETS-protected groups. Enhanced recovery in the ETS-protected group was indicated by the tibial function index, motor nerve conduction velocity, muscle contractile force tests, and the histological results. In contrast, early sensory nerve protection in ETE neurorrhaphy impaired the recovery of the regenerated axons and diminished the contractile force of the denervated muscle. CONCLUSIONS Early sensory protection in reverse ETS neurorrhaphy is an effective method for improving the functional recovery of chronically denervated muscle following peripheral nerve injury in rats.
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Affiliation(s)
- Qingtian Li
- Department of Trauma and Orthopaedics, Peking University People's Hospital, Beijing, China
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31
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Madison RD, Robinson GA. Accuracy of regenerating motor neurons: influence of diffusion in denervated nerve. Neuroscience 2014; 273:128-40. [PMID: 24846614 DOI: 10.1016/j.neuroscience.2014.05.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2014] [Revised: 05/07/2014] [Accepted: 05/09/2014] [Indexed: 12/21/2022]
Abstract
Following injury to a peripheral nerve the denervated distal nerve segment undergoes remarkable changes including loss of the blood-nerve barrier, Schwann cell proliferation, macrophage invasion, and the production of many cytokines and neurotrophic factors. The aggregate consequence of such changes is that the denervated nerve becomes a permissive and even preferred target for regenerating axons from the proximal nerve segment. The possible role that an original end-organ target (e.g. muscle) may play in this phenomenon during the regeneration period is largely unexplored. We used the rat femoral nerve as an in vivo model to begin to address this question. We also examined the effects of disrupting communication with muscle in terms of accuracy of regenerating motor neurons as judged by their ability to correctly project to their original terminal nerve branch. Our results demonstrate that the accuracy of regenerating motor neurons is dependent upon the denervated nerve segment remaining in uninterrupted continuity with muscle. We hypothesized that this influence of muscle on the denervated nerve might be via diffusion-driven movement of biomolecules or the active axonal transport that continues in severed axons for several days in the rat, so we devised experiments to separate these two possibilities. Our data show that disrupting ongoing diffusion-driven movement in a denervated nerve significantly reduces the accuracy of regenerating motor neurons.
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Affiliation(s)
- R D Madison
- Department of Surgery, Duke University Medical Center, Durham, NC 27710, United States; Biological Laboratory Research and Development Service of the Veterans Affairs Medical Center, Durham, NC 27705, United States.
| | - G A Robinson
- Department of Surgery, Duke University Medical Center, Durham, NC 27710, United States
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Sustained delivery of VEGF maintains innervation and promotes reperfusion in ischemic skeletal muscles via NGF/GDNF signaling. Mol Ther 2014; 22:1243-1253. [PMID: 24769910 DOI: 10.1038/mt.2014.76] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 04/17/2014] [Indexed: 12/14/2022] Open
Abstract
Tissue reinnervation following trauma, disease, or transplantation often presents a significant challenge. Here, we show that the delivery of vascular endothelial growth factor (VEGF) from alginate hydrogels ameliorates loss of skeletal muscle innervation after ischemic injury by promoting both maintenance and regrowth of damaged axons in mice. Nerve growth factor (NGF) and glial-derived neurotrophic factor (GDNF) mediated VEGF-induced axonal regeneration, and the expression of both is induced by VEGF presentation. Using both in vitro and in vivo modeling approaches, we demonstrate that the activity of NGF and GDNF regulates VEGF-driven angiogenesis, controlling endothelial cell sprouting and blood vessel maturation. Altogether, these studies produce evidence of new mechanisms of VEGF action, further broaden the understanding of the roles of NGF and GDNF in angiogenesis and axonal regeneration, and suggest approaches to improve axonal and ischemic tissue repair therapies.
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Wu-Fienberg Y, Moore AM, Marquardt LM, Newton P, Johnson PJ, Mackinnon SE, Sakiyama-Elbert SE, Wood MD. Viral transduction of primary Schwann cells using a Cre-lox system to regulate GDNF expression. Biotechnol Bioeng 2014; 111:1886-94. [PMID: 24728940 DOI: 10.1002/bit.25247] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 02/21/2014] [Accepted: 03/24/2014] [Indexed: 11/06/2022]
Abstract
Glial cell-line-derived neurotrophic factor (GDNF) is a potent neurotrophic factor known to enhance motor nerve regeneration following its delivery. However, recent studies have determined that extended GDNF delivery to regenerating axons can entrap motor axons at the site of GDNF delivery. This entrapment leads to reduced motor axons available to reinnervate muscle. To address this issue, we designed a cell-based GDNF expression system that can temporally regulate protein expression using an inducible gene excision mechanism to prevent entrapment at the site of expression. To design this system for regulation of GDNF expression, we transduced two lentiviral vectors, one containing a constitutively active GDNF transgene flanked by two loxP sites, and the other containing a tetracycline-inducible cre transgene along with its constitutively active transactivator, into Schwann cells (SCs). These SCs over-express GDNF, but expression can be suppressed through the administration of tetracycline family antibiotics, such as doxycycline. The engineered SCs produced significantly more GDNF as compared to untransduced controls, as measured by enzyme-linked immunosorbent assay (ELISA). Following doxycycline treatment, these SCs produced significantly lower levels of GDNF and induced less neurite extension as compared to untreated SCs. Engineered SCs treated with doxycycline showed a marked increase in Cre recombinase expression, as visualized by immunohistochemistry (IHC), providing evidence of a mechanism for the observed changes in GDNF expression levels and biological activity. This cell-based GDNF expression system could have potential for future in vivo studies to provide a temporally controlled GDNF source to promote axon growth.
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Affiliation(s)
- Yuewei Wu-Fienberg
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Washington University School of Medicine, Campus Box 8238, 660 South Euclid Avenue, St. Louis, Missouri, 63110
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Hausner T, Marvaldi L, Márton G, Pajer K, Hopf R, Schmidhammer R, Hausott B, Redl H, Nógrádi A, Klimaschewski L. Inhibition of calpains fails to improve regeneration through a peripheral nerve conduit. Neurosci Lett 2014; 566:280-5. [PMID: 24631569 PMCID: PMC4000267 DOI: 10.1016/j.neulet.2014.03.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 02/18/2014] [Accepted: 03/05/2014] [Indexed: 12/17/2022]
Abstract
Calpain inhibitor leupeptin locally applied to transected sciatic nerve of rats. Axon number and myelination not significantly increased 3 months after lesion. No difference in behavioral tests after nerve regeneration.
Intramuscular injection of the calpain inhibitor leupeptin promotes peripheral nerve regeneration in primates (Badalamente et al., 1989 [13]), and direct positive effects of leupeptin on axon outgrowth were observed in vitro (Hausott et al., 2012 [12]). In this study, we applied leupeptin (2 mg/ml) directly to collagen-filled nerve conduits in the rat sciatic nerve transection model. Analysis of myelinated axons and retrogradely labeled motoneurons as well as functional ‘CatWalk’ video analysis did not reveal significant differences between vehicle controls and leupeptin treated animals. Therefore, leupeptin does not improve nerve regeneration via protease inhibition in regrowing axons or in surrounding Schwann cells following a single application to a peripheral nerve conduit suggesting indirect effects on motor endplate integrity if applied systemically.
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Affiliation(s)
- Thomas Hausner
- Austrian Cluster of Tissue Regeneration and Ludwig Boltzmann Institute for Experimental and Clinical Traumatology at the Research Centre for Traumatology of the Austrian Workers' Compensation Board (AUVA), Donaueschingenstr. 13, 1200 Vienna, Austria; Department of Trauma Surgery and Sports Traumatology, Paracelsus Medical University, Müllner Hauptstr. 48-50, 5020 Salzburg, Austria; Department of Surgery, State Hospital Hainburg, Hofmeisterstr. 70, 2410 Hainburg, Austria
| | - Letizia Marvaldi
- Division of Neuroanatomy, Department of Anatomy, Histology and Embryology, Innsbruck Medical University, Muellerstrasse 59, 6020 Innsbruck, Austria
| | - Gábor Márton
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Szeged, Hungary
| | - Krisztián Pajer
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Szeged, Hungary
| | - Rudolf Hopf
- Austrian Cluster of Tissue Regeneration and Ludwig Boltzmann Institute for Experimental and Clinical Traumatology at the Research Centre for Traumatology of the Austrian Workers' Compensation Board (AUVA), Donaueschingenstr. 13, 1200 Vienna, Austria
| | - Robert Schmidhammer
- Austrian Cluster of Tissue Regeneration and Ludwig Boltzmann Institute for Experimental and Clinical Traumatology at the Research Centre for Traumatology of the Austrian Workers' Compensation Board (AUVA), Donaueschingenstr. 13, 1200 Vienna, Austria; Vienna Private Clinic, Pelikangasse 15, 1090 Vienna, Austria
| | - Barbara Hausott
- Division of Neuroanatomy, Department of Anatomy, Histology and Embryology, Innsbruck Medical University, Muellerstrasse 59, 6020 Innsbruck, Austria
| | - Heinz Redl
- Austrian Cluster of Tissue Regeneration and Ludwig Boltzmann Institute for Experimental and Clinical Traumatology at the Research Centre for Traumatology of the Austrian Workers' Compensation Board (AUVA), Donaueschingenstr. 13, 1200 Vienna, Austria
| | - Antal Nógrádi
- Austrian Cluster of Tissue Regeneration and Ludwig Boltzmann Institute for Experimental and Clinical Traumatology at the Research Centre for Traumatology of the Austrian Workers' Compensation Board (AUVA), Donaueschingenstr. 13, 1200 Vienna, Austria; Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Szeged, Hungary.
| | - Lars Klimaschewski
- Division of Neuroanatomy, Department of Anatomy, Histology and Embryology, Innsbruck Medical University, Muellerstrasse 59, 6020 Innsbruck, Austria.
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Madison RD, McGee C, Rawson R, Robinson GA. Extracellular vesicles from a muscle cell line (C2C12) enhance cell survival and neurite outgrowth of a motor neuron cell line (NSC-34). J Extracell Vesicles 2014; 3:22865. [PMID: 24563732 PMCID: PMC3930942 DOI: 10.3402/jev.v3.22865] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 01/24/2014] [Accepted: 01/28/2014] [Indexed: 12/26/2022] Open
Abstract
Introduction There is renewed interest in extracellular vesicles over the past decade or 2 after initially being thought of as simple cellular garbage cans to rid cells of unwanted components. Although there has been intense research into the role of extracellular vesicles in the fields of tumour and stem cell biology, the possible role of extracellular vesicles in nerve regeneration is just in its infancy. Background When a peripheral nerve is damaged, the communication between spinal cord motor neurons and their target muscles is disrupted and the result can be the loss of coordinated muscle movement. Despite state-of-the-art surgical procedures only approximately 10% of adults will recover full function after peripheral nerve repair. To improve upon such results will require a better understanding of the basic mechanisms that influence axon outgrowth and the interplay between the parent motor neuron and the distal end organ of muscle. It has previously been shown that extracellular vesicles are immunologically tolerated, display targeting ligands on their surface, and can be delivered in vivo to selected cell populations. All of these characteristics suggest that extracellular vesicles could play a significant role in nerve regeneration. Methods We have carried out studies using 2 very well characterized cell lines, the C2C12 muscle cell line and the motor neuron cell line NSC-34 to ask the question: Do extracellular vesicles from muscle influence cell survival and/or neurite outgrowth of motor neurons? Conclusion Our results show striking effects of extracellular vesicles derived from the muscle cell line on the motor neuron cell line in terms of neurite outgrowth and survival.
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Affiliation(s)
- Roger D Madison
- Department of Surgery, Duke University Medical Center, Durham, NC, USA ; Research Service of the Veterans Affairs Medical Center, Durham, NC, USA
| | - Christopher McGee
- Research Service of the Veterans Affairs Medical Center, Durham, NC, USA
| | - Renee Rawson
- Department of Surgery, Duke University Medical Center, Durham, NC, USA
| | - Grant A Robinson
- Department of Surgery, Duke University Medical Center, Durham, NC, USA
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Functional recovery of denervated skeletal muscle with sensory or mixed nerve protection: a pilot study. PLoS One 2013; 8:e79746. [PMID: 24244555 PMCID: PMC3820544 DOI: 10.1371/journal.pone.0079746] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 09/24/2013] [Indexed: 01/02/2023] Open
Abstract
Functional recovery is usually poor following peripheral nerve injury when reinnervation is delayed. Early innervation by sensory nerve has been indicated to prevent atrophy of the denervated muscle. It is hypothesized that early protection with sensory axons is adequate to improve functional recovery of skeletal muscle following prolonged denervation of mixed nerve injury. In this study, four groups of rats received surgical denervation of the tibial nerve. The proximal and distal stumps of the tibial nerve were ligated in all animals except for those in the immediate repair group. The experimental groups underwent denervation with nerve protection of peroneal nerve (mixed protection) or sural nerve (sensory protection). The experimental and unprotected groups had a stage II surgery in which the trimmed proximal and distal tibial nerve stumps were sutured together. After 3 months of recovery, electrophysiological, histological and morphometric parameters were assessed. It was detected that the significant muscle atrophy and a good preserved structure of the muscle were observed in the unprotected and protective experimental groups, respectively. Significantly fewer numbers of regenerated myelinated axons were observed in the sensory-protected group. Enhanced recovery in the mixed protection group was indicated by the results of the muscle contraction force tests, regenerated myelinated fiber, and the results of the histological analysis. Our results suggest that early axons protection by mixed nerve may complement sensory axons which are required for promoting functional recovery of the denervated muscle natively innervated by mixed nerve.
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Releasing the brake: restoring fast axonal transport in neurodegenerative disorders. Trends Cell Biol 2013; 23:634-43. [PMID: 24091156 DOI: 10.1016/j.tcb.2013.08.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 08/26/2013] [Accepted: 08/27/2013] [Indexed: 12/15/2022]
Abstract
Emerging evidence suggests that the dysregulation of fast axonal transport (FAT) plays a crucial role in several neurodegenerative disorders. Some of these diseases are caused by mutations affecting the molecular motors or adaptors that mediate FAT, and transport defects in organelles such as mitochondria and vesicles are observed in most, if not all neurodegenerative disorders. The relationship between neurodegenerative disorders and FAT is probably due to the extreme polarization of neurons, which extend long processes such as axons and dendrites. These characteristics render neurons particularly sensitive to transport alterations. Here we review the impact of such alterations on neuronal survival. We also discuss various strategies that might restore FAT, potentially slowing disease progression.
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Johnson PJ, Wood MD, Moore AM, Mackinnon SE. Tissue engineered constructs for peripheral nerve surgery. Eur Surg 2013; 45. [PMID: 24385980 DOI: 10.1007/s10353-013-0205-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Tissue engineering has been defined as "an interdisciplinary field that applies the principles of engineering and life sciences toward the development of biological substitutes that restore, maintain, or improve tissue function or a whole organ". Traumatic peripheral nerve injury resulting in significant tissue loss at the zone of injury necessitates the need for a bridge or scaffold for regenerating axons from the proximal stump to reach the distal stump. METHODS A review of the literature was used to provide information on the components necessary for the development of a tissue engineered peripheral nerve substitute. Then, a comprehensive review of the literature is presented composed of the studies devoted to this goal. RESULTS Extensive research has been directed toward the development of a tissue engineered peripheral nerve substitute to act as a bridge for regenerating axons from the proximal nerve stump seeking the distal nerve. Ideally this nerve substitute would consist of a scaffold component that mimics the extracellular matrix of the peripheral nerve and a cellular component that serves to stimulate and support regenerating peripheral nerve axons. CONCLUSIONS The field of tissue engineering should consider its challenge to not only meet the autograft "gold standard" but also to understand what drives and inhibits nerve regeneration in order to surpass the results of an autograft.
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Affiliation(s)
- P J Johnson
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Washington University School of Medicine, 660 South Euclid, 8238, Saint Louis, MO 63110, USA
| | - M D Wood
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Washington University School of Medicine, 660 South Euclid, 8238, Saint Louis, MO 63110, USA
| | - A M Moore
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Washington University School of Medicine, 660 South Euclid, 8238, Saint Louis, MO 63110, USA
| | - S E Mackinnon
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Washington University School of Medicine, 660 South Euclid, 8238, Saint Louis, MO 63110, USA
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The effects of target skeletal muscle cells on dorsal root ganglion neuronal outgrowth and migration in vitro. PLoS One 2013; 8:e52849. [PMID: 23341911 PMCID: PMC3544851 DOI: 10.1371/journal.pone.0052849] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Accepted: 11/21/2012] [Indexed: 11/19/2022] Open
Abstract
Targets of neuronal innervations play a vital role in regulating the survival and differentiation of innervating neurotrophin-responsive neurons. During development, neurons extend axons to their targets, and then their survival become dependent on the trophic substances secreted by their target cells. Sensory endings were present on myoblasts, myotubes, and myofibers in all intrafusal bundles regardless of age. The interdependence of sensory neurons and skeletal muscle (SKM) cells during both embryonic development and the maintenance of the mature functional state has not been fully understood. In the present study, neuromuscular cocultures of organotypic dorsal root ganglion (DRG) explants and dissociate SKM cells were established. Using this culture system, the morphological relationship between DRG neurons and SKM cells, neurites growth and neuronal migration were investigated. The migrating neurons were determined by fluorescent labeling of microtubule-associated protein-2 (MAP-2) and neurofilament 200 (NF-200) or growth-associated protein 43 (GAP-43). The expression of NF-200 and GAP-43 and their mRNAs was evaluated by Western blot assay and real time-PCR analysis. The results reveal that DRG explants showed more dense neurites outgrowth in neuromuscular cocultures as compared with that in the culture of DRG explants alone. The number of total migrating neurons (the MAP-2-expressing neurons) and the percentage NF-200-immunoreactive (IR) and GAP-43-IR neurons increased significantly in the presence of SKM cells. The levels of NF-200 and GAP-43 and their mRNAs increased significantly in neuromuscular cocultures as compared with that in the culture of DRG explants alone. These results suggested that target SKM cells play an important role in regulating neuronal protein synthesis, promoting neuritis outgrowth and neuronal migration of DRG explants in vitro. These results not only provide new clues for a better understanding of the association of SKM cells with DRG sensory neurons during development, they may also have implications for axonal regeneration after nerve injury.
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Future Perspectives in Nerve Repair and Regeneration. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2013; 109:165-92. [DOI: 10.1016/b978-0-12-420045-6.00008-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Klimaschewski L, Hausott B, Angelov DN. The pros and cons of growth factors and cytokines in peripheral axon regeneration. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2013; 108:137-71. [PMID: 24083434 DOI: 10.1016/b978-0-12-410499-0.00006-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Injury to a peripheral nerve induces a complex cellular and molecular response required for successful axon regeneration. Proliferating Schwann cells organize into chains of cells bridging the lesion site, which is invaded by macrophages. Approximately half of the injured neuron population sends out axons that enter the glial guidance channels in response to secreted neurotrophic factors and neuropoietic cytokines. These lesion-associated polypeptides create an environment that is highly supportive for axon regrowth, particularly after acute injury, and ensure that the vast majority of regenerating axons are directed toward the distal nerve stump. Unfortunately, most neurotrophic factors and neuropoietic cytokines are also strong stimulators of axonal sprouting. Although some of the axonal branches will withdraw at later stages, the sprouting effect contributes to the misdirection of reinnervation that results in the lack of functional recovery observed in many patients with peripheral nerve injuries. Here, we critically review the role of neuronal growth factors and cytokines during axon regeneration in the peripheral nervous system. Their differential effects on axon elongation and sprouting were elucidated in various studies on intraneuronal signaling mechanisms following nerve lesion. The present data define a goal for future therapeutic strategies, namely, to selectively stimulate a Ras/Raf/ERK-mediated axon elongation program over an intrinsic PI3K-dependent axonal sprouting program in lesioned motor and sensory neurons. Instead of modulating growth factor or cytokine levels at the lesion site, targeting specific intraneuronal molecules, such as the negative feedback inhibitors of ERK signaling, has been shown to promote long-distance regeneration while avoiding sprouting of regenerating axons until they have reached their target areas.
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Affiliation(s)
- Lars Klimaschewski
- Division of Neuroanatomy, Department of Anatomy and Histology, Innsbruck Medical University, Innsbruck, Austria
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Santosa KB, Jesuraj NJ, Viader A, MacEwan M, Newton P, Hunter DA, Mackinnon SE, Johnson PJ. Nerve allografts supplemented with schwann cells overexpressing glial-cell-line-derived neurotrophic factor. Muscle Nerve 2012; 47:213-23. [PMID: 23169341 DOI: 10.1002/mus.23490] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/03/2012] [Indexed: 12/14/2022]
Abstract
INTRODUCTION We sought to determine whether supplementation of acellular nerve allografts (ANAs) with Schwann cells overexpressing GDNF (G-SCs) would enhance functional recovery after peripheral nerve injury. METHODS SCs expanded in vitro were infected with a lentiviral vector to induce GDNF overexpression. Wild-type SCs (WT-SCs) and G-SCs were seeded into ANAs used to repair a 14-mm nerve gap defect. Animals were harvested after 6 and 12 weeks for histomorphometric and muscle force analysis. RESULTS At 6 weeks, histomorphometry revealed that ANAs supplemented with G-SCs promoted similar regeneration compared with isograft at midgraft. However, G-SCs failed to promote regeneration into the distal stump. At 12 weeks, ANAs with G-SCs had lower maximum and specific force production compared with controls. CONCLUSIONS The combined results suggest that consistent overexpression of GDNF by G-SCs trapped axons in the graft and prevented functional regeneration.
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Affiliation(s)
- Katherine B Santosa
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri 63110, USA
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Lin S, Xu L, Hu S, Zhang C, Wang Y, Xu J. Optimal time-point for neural stem cell transplantation to delay denervated skeletal muscle atrophy. Muscle Nerve 2012; 47:194-201. [PMID: 23042154 DOI: 10.1002/mus.23447] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/01/2012] [Indexed: 12/22/2022]
Abstract
INTRODUCTION Transplantation of neural stem cells (NSCs) is a promising treatment to delay denervated skeletal muscle atrophy; however, the optimal time-point between peripheral nerve injury and NSC transplantation needs to be determined. METHODS Improvement in rat gastrocnemius muscle function was evaluated after NSCs were transplanted into sectioned distal tibial nerves. We also assessed survival and differentiation. ANOVA was used to compare the mean value of the number of neuron-like cells, cross-sectional area amelioration, the amount of activated fibers, and latency and amplitude of the gastrocnemius compound muscle action potential. RESULTS The group in which the NSCs were transplanted 1 week after tibial nerve transection had the largest number of neuron-like cells, maximum cross-sectional area amelioration, and maximum amount of activated gastrocnemius fibers compared with all other groups (P < 0.01). CONCLUSIONS The optimal time-point for NSC transplantation for delaying denervated skeletal muscle atrophy is 1 week after severing the nerve.
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Affiliation(s)
- Sen Lin
- Department of Orthopaedics, Shanghai Sixth People's Hospital and School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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Li H, Zhang W, Liu G, Li J, Liu H, Li Z. Expression of tyrosine kinase receptors in cultured dorsal root ganglion neurons in the presence of monosialoganglioside and skeletal muscle cells. J Muscle Res Cell Motil 2012; 33:341-50. [PMID: 22968393 DOI: 10.1007/s10974-012-9322-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Accepted: 09/03/2012] [Indexed: 12/30/2022]
Abstract
The neurotrophic factor-like activity of monosialoganglioside (GM1) has been shown to activate tyrosine kinase receptors (Trk). Targets of neuronal innervation play a vital role in regulating the survival and differentiation of innervating neurotrophin-responsive neurons. Both GM1 and target skeletal muscle (SKM) cells are essential for the maintenance of the function of neurons. However, much less is known about the effects of GM1 or/and target SKM cells on the expression of Trk receptors in dorsal root ganglion (DRG) neurons. Here we have tested what extent to the expression of TrkA, TrkB, and TrkC receptors in primary cultured of DRG neurons in absence or presence of GM1 or/and SKM cells. In this experiment, we found that: (1) GM1 promoted expression of TrkA and TrkB but not TrkC in primary cultured DRG neurons; (2) target SKM cells promoted expression of TrkC but not TrkA and TrkB in neuromuscular cocultures without GM1 treatment; and (3) GM1 and target SKM cells had additional effects on expression of these three Trk receptors. The results of the present study offered new clues for a better understanding of the association of GM1 and target SKM on the expression of Trk receptors.
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Affiliation(s)
- Hao Li
- Department of Anatomy, Shandong University School of Medicine, Jinan 250012, China.
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Zhang W, Li H, Xing Z, Yuan H, Kindy MS, Li Z. Expression of mRNAs for PPT, CGRP, NF-200, and MAP-2 in cocultures of dissociated DRG neurons and skeletal muscle cells in administration of NGF or NT-3. Folia Histochem Cytobiol 2012; 50:312-8. [PMID: 22763971 DOI: 10.5603/fhc.2012.0041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 02/03/2012] [Indexed: 11/25/2022] Open
Abstract
Both neurotrophins (NTs) and target skeletal muscle (SKM) cells are essential for the maintenance of the function of neurons and nerve-muscle communication. However, much less is known about the association of target SKM cells with distinct NTs on the expression of mRNAs for preprotachykinin (PPT), calcitonin-gene related peptide (CGRP), neurofilament 200 (NF-200), and microtubule associated protein 2 (MAP-2) in dorsal root ganglion (DRG) sensory neurons. In the present study, a neuromuscular coculture model of dissociated dorsal root ganglion (DRG) neurons and SKM cells was established. The morphology of DRG neurons and SKM cells in coculture was observed with an inverted phase contrast microscope. The effects of nerve growth factor (NGF) or neurotrophin-3 (NT-3) on the expression of mRNAs for PPT, CGRP, NF-200, and MAP-2 was analyzed by real time-PCR assay. The morphology of DRG neuronal cell bodies and SKM cells in neuromuscular coculture at different conditions was similar. The neurons presented evidence of dense neurite outgrowth in the presence of distinct NTs in neuromuscular cocultures. NGF and NT-3 increased mRNA levels of PPT, CGRP, and NF-200, but not MAP-2, in neuromuscular cocultures. These results offer new clues towards a better understanding of the association of target SKM cells with distinct NTs on the expression of mRNAs for PPT, CGRP, NF-200 and MAP-2, and implicate the association of target SKM cells and NTs with DRG sensory neuronal phenotypes.
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Affiliation(s)
- Weiwei Zhang
- Department of Anatomy, Shandong University School of Medicine, Jinan, China
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Omori M, Sakakibara S, Hashikawa K, Terashi H, Tahara S, Sugiyama D. Comparison of reinnervation for preservation of denervated muscle volume with motor and sensory nerve: An experimental study. J Plast Reconstr Aesthet Surg 2012; 65:943-9. [DOI: 10.1016/j.bjps.2012.01.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 12/26/2011] [Accepted: 01/26/2012] [Indexed: 11/26/2022]
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Boyd KU, Nimigan AS, Mackinnon SE. Nerve reconstruction in the hand and upper extremity. Clin Plast Surg 2012; 38:643-60. [PMID: 22032591 DOI: 10.1016/j.cps.2011.07.008] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the management of traumatic peripheral nerve injuries, the severity or degree of injury dictates the decision making between surgical management versus conservative management and serial examination. This review explores some of the recent literature, specifically addressing recent basic science advances in end-to-side and reverse end-to-side recovery, Schwann cell migration, and neuropathic pain. The management of nerve gaps, including the use of nerve conduits and acellularized nerve allografts, is examined. Current commonly performed nerve transfers are detailed with focus on both motor and sensory nerve transfers, their indications, and a basic overview of selected surgical techniques.
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Affiliation(s)
- Kirsty U Boyd
- Division of Plastic and Reconstructive Surgery, Department of Surgery, University of Ottawa, 1053 Carling Avenue, Ottawa, ON K1Y 4E9, Canada
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Jia H, Wang Y, Tong XJ, Liu GB, Li Q, Zhang LX, Sun XH. Sciatic nerve repair by acellular nerve xenografts implanted with BMSCs in rats xenograft combined with BMSCs. Synapse 2011; 66:256-69. [PMID: 22127791 DOI: 10.1002/syn.21508] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Accepted: 11/07/2011] [Indexed: 12/23/2022]
Abstract
Acellular nerves possess the structural and biochemical features similar to those of naive endoneurial tubes, and have been proved bioactive for allogeneil graft in nerve tissue engineering. However, the source of allogenic donators is restricted in clinical treatment. To explore sufficient substitutes for acellular nerve allografts (ANA), we investigated the effectiveness of acellular nerve xenografts (ANX) combined with bone marrow stromal cells (BMSCs) on repairing peripheral nerve injuries. The acellular nerves derived from Sprague-Dawley rats and New Zealand rabbits were prepared, respectively, and BMSCs were implanted into the nerve scaffolds and cultured in vitro. All the grafts were employed to bridge 1 cm rat sciatic nerve gaps. Fifty Wistar rats were randomly divided into five groups (n = 10 per group): ANA group, ANX group, BMSCs-laden ANA group, BMSCs-laden ANX group, and autologous nerve graft group. At 8 weeks post-transplantation, electrophysiological study was performed and the regenerated nerves were assayed morphologically. Besides, growth-promoting factors in the regenerated tissues following the BMSCs integration were detected. The results indicated that compared with the acellular nerve control groups, nerve regeneration and functional rehabilitation for the xenogenic nerve transplantation integrated with BMSCs were advanced significantly, and the rehabilitation efficacy was comparable with that of the autografting. The expression of neurotrophic factors in the regenerated nerves, together with that of brain-derived neurotrophic factor (BDNF) in the spinal cord and muscles were elevated largely. In conclusion, ANX implanted with BMSCs could replace allografts to promote nerve regeneration effectively, which offers a reliable approach for repairing peripheral nerve defects.
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Affiliation(s)
- Hua Jia
- Department of Anatomy, College of Basic Medical Sciences, Ningxia Medical University, Yinchuan 750004, China
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Kale SS, Glaus SW, Yee A, Nicoson MC, Hunter DA, Mackinnon SE, Johnson PJ. Reverse end-to-side nerve transfer: from animal model to clinical use. J Hand Surg Am 2011; 36:1631-1639.e2. [PMID: 21872405 DOI: 10.1016/j.jhsa.2011.06.029] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 06/23/2011] [Accepted: 06/24/2011] [Indexed: 02/02/2023]
Abstract
PURPOSE Functional recovery after peripheral nerve injury is predominantly influenced by time to reinnervation and number of regenerated motor axons. For nerve injuries in which incomplete regeneration is anticipated, a reverse end-to-side (RETS) nerve transfer might be useful to augment the regenerating nerve with additional axons and to more quickly reinnervate target muscle. This study evaluates the ability of peripheral nerve axons to regenerate across an RETS nerve transfer. We present a case report demonstrating its potential clinical applicability. METHODS Thirty-six Lewis rats were randomized into 3 groups. In group 1 (negative control), the tibial nerve was transected and prevented from regenerating. In group 2 (positive control), the tibial and peroneal nerves were transected, and an end-to-end (ETE) nerve transfer was performed. In group 3 (experimental model), the tibial nerve and peroneal nerves were transected, and an RETS nerve transfer was performed between the proximal end of the peroneal nerve and the side of the denervated distal tibial stump. Nerve histomorphometry and perfused muscle mass were evaluated. Six Thy1-GFP transgenic Sprague Dawley rats, expressing green fluorescent protein in their neural tissues, also had the RETS procedure for evaluation with confocal microscopy. RESULTS Nerve histomorphometry showed little to no regeneration in chronic denervation animals but statistically similar regeneration in ETE and RETS animals at 5 and 10 weeks. Muscle mass preservation was similar between ETE and RETS groups by 10 weeks and significantly better than negative controls at both time points. Nerve regeneration was robust across the RETS coaptation of Thy1-GFP rats by 5 weeks. CONCLUSIONS Axonal regeneration occurs across an RETS coaptation. An RETS nerve transfer might augment motor recovery when less-than-optimal recovery is otherwise anticipated. TYPE OF STUDY/LEVEL OF EVIDENCE Therapeutic I.
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Affiliation(s)
- Santosh S Kale
- Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, St. Louis, MO, USA
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Abstract
The postsurgical period during which neurons remain without target connections (chronic axotomy) and distal nerve stumps and target muscles are denervated (chronic denervation) deleteriously affects functional recovery. An autologous nerve graft and cross-suture paradigm in Sprague Dawley rats was used to systematically and independently control time of motoneuron axotomy, denervation of distal nerve sheaths, and muscle denervation to determine relative contributions of each factor to recovery failure. Tibial (TIB) nerve was cross-sutured to common peroneal (CP) nerve via a contralateral 15 mm nerve autograft to reinnervate the tibialis anterior (TA) muscle immediately or after prolonging TIB axotomy, CP autograft denervation, or TA muscle denervation. Numbers of motoneurons that reinnervated TA muscle declined exponentially from 99 ± 15 to asymptotic mean (± SE) values of 35 ± 1, 41 ± 10, and 13 ± 5, respectively. Enlarged reinnervated motor units fully compensated for reduced motoneuron numbers after prolonged axotomy and autograft denervation, but the maximal threefold enlargement did not compensate for the severe loss of regenerating nerves through chronically denervated nerve stumps and for failure of reinnervated muscle fibers to recover from denervation atrophy. Muscle force, weight, and cross-sectional area declined. Our results demonstrate that chronic denervation of the distal stump plays a key role in reduced nerve regeneration, but the denervated muscle is also a contributing factor. That chronic Schwann cell denervation within the nerve autograft reduced regeneration less than after the denervation of both CP nerve stump and TA muscle, argues that chronic muscle denervation negatively impacts nerve regeneration.
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