1
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Hardy PB, Wang BY, Chan KM, Webber CA, Senger JLB. The use of electrical stimulation to enhance recovery following peripheral nerve injury. Muscle Nerve 2024. [PMID: 39347555 DOI: 10.1002/mus.28262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 09/04/2024] [Accepted: 09/07/2024] [Indexed: 10/01/2024]
Abstract
Peripheral nerve injury is common and can have devastating consequences. In severe cases, functional recovery is often poor despite surgery. This is primarily due to the exceedingly slow rate of nerve regeneration at only 1-3 mm/day. The local environment in the distal nerve stump supportive of nerve regrowth deteriorates over time and the target end organs become atrophic. To overcome these challenges, investigations into treatments capable of accelerating nerve regrowth are of great clinical relevance and are an active area of research. One intervention that has shown great promise is perioperative electrical stimulation. Postoperative stimulation helps to expedite the Wallerian degeneration process and reduces delays caused by staggered regeneration at the site of nerve injury. By contrast, preoperative "conditioning" stimulation increases the rate of nerve regrowth along the nerve trunk. Over the past two decades, a rich body of literature has emerged that provides molecular insights into the mechanism by which electrical stimulation impacts nerve regeneration. The end result is upregulation of regeneration-associated genes in the neuronal body and accelerated transport to the axon front for regrowth. The efficacy of brief electrical stimulation on patients with peripheral nerve injuries was demonstrated in a number of randomized controlled trials on compressive, transection and traction injuries. As approved equipment to deliver this treatment is becoming available, it may be feasible to deploy this novel treatment in a wide range of clinical settings.
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Affiliation(s)
- Paige B Hardy
- Department of Surgery, University of Alberta, Edmonton, Alberta, Canada
| | - Bonnie Y Wang
- Division of Physical Medicine and Rehabilitation, University of Alberta, Edmonton, Alberta, Canada
| | - K Ming Chan
- Division of Physical Medicine and Rehabilitation, University of Alberta, Edmonton, Alberta, Canada
| | | | - Jenna-Lynn B Senger
- Division of Plastic & Reconstructive Surgery, University of British Columbia, Vancouver, British Columbia, Canada
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2
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Dahlin LB. The Dynamics of Nerve Degeneration and Regeneration in a Healthy Milieu and in Diabetes. Int J Mol Sci 2023; 24:15241. [PMID: 37894921 PMCID: PMC10607341 DOI: 10.3390/ijms242015241] [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: 09/01/2023] [Revised: 10/06/2023] [Accepted: 10/09/2023] [Indexed: 10/29/2023] Open
Abstract
Appropriate animal models, mimicking conditions of both health and disease, are needed to understand not only the biology and the physiology of neurons and other cells under normal conditions but also under stress conditions, like nerve injuries and neuropathy. In such conditions, understanding how genes and different factors are activated through the well-orchestrated programs in neurons and other related cells is crucial. Knowledge about key players associated with nerve regeneration intended for axonal outgrowth, migration of Schwann cells with respect to suitable substrates, invasion of macrophages, appropriate conditioning of extracellular matrix, activation of fibroblasts, formation of endothelial cells and blood vessels, and activation of other players in healthy and diabetic conditions is relevant. Appropriate physical and chemical attractions and repulsions are needed for an optimal and directed regeneration and are investigated in various nerve injury and repair/reconstruction models using healthy and diabetic rat models with relevant blood glucose levels. Understanding dynamic processes constantly occurring in neuropathies, like diabetic neuropathy, with concomitant degeneration and regeneration, requires advanced technology and bioinformatics for an integrated view of the behavior of different cell types based on genomics, transcriptomics, proteomics, and imaging at different visualization levels. Single-cell-transcriptional profile analysis of different cells may reveal any heterogeneity among key players in peripheral nerves in health and disease.
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Affiliation(s)
- Lars B. Dahlin
- Department of Translational Medicine—Hand Surgery, Lund University, SE-205 02 Malmö, Sweden; ; Tel.: +46-40-33-17-24
- Department of Hand Surgery, Skåne University Hospital, SE-205 02 Malmö, Sweden
- Department of Biomedical and Clinical Sciences, Linköping University, SE-581 83 Linköping, Sweden
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3
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Golshadi M, Claffey EF, Grenier JK, Miller A, Willand M, Edwards MG, Moore TP, Sledziona M, Gordon T, Borschel GH, Cheetham J. Delay modulates the immune response to nerve repair. NPJ Regen Med 2023; 8:12. [PMID: 36849720 PMCID: PMC9970988 DOI: 10.1038/s41536-023-00285-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 02/10/2023] [Indexed: 03/01/2023] Open
Abstract
Effective regeneration after peripheral nerve injury requires macrophage recruitment. We investigated the activation of remodeling pathways within the macrophage population when repair is delayed and identified alteration of key upstream regulators of the inflammatory response. We then targeted one of these regulators, using exogenous IL10 to manipulate the response to injury at the repair site. We demonstrate that this approach alters macrophage polarization, promotes macrophage recruitment, axon extension, neuromuscular junction formation, and increases the number of regenerating motor units reaching their target. We also demonstrate that this approach can rescue the effects of delayed nerve graft.
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Affiliation(s)
- Masoud Golshadi
- Cornell University College of Veterinary Medicine, 930 Campus Road, Ithaca, NY, 14853, USA
| | - Elaine F Claffey
- Cornell University College of Veterinary Medicine, 930 Campus Road, Ithaca, NY, 14853, USA
| | - Jennifer K Grenier
- Cornell University College of Veterinary Medicine, 930 Campus Road, Ithaca, NY, 14853, USA
| | - Andrew Miller
- Cornell University College of Veterinary Medicine, 930 Campus Road, Ithaca, NY, 14853, USA
| | - Michael Willand
- Epineuron Technologies Inc, 5100 Orbitor Dr., Mississauga, ON, L4W 5R8, Canada
| | | | - Tim P Moore
- Cornell University College of Veterinary Medicine, 930 Campus Road, Ithaca, NY, 14853, USA
| | - Michael Sledziona
- Cornell University College of Veterinary Medicine, 930 Campus Road, Ithaca, NY, 14853, USA
| | - Tessa Gordon
- Hospital for Sick Children, 555 University Ave, Toronto, ON, M5G 1×8, Canada
| | | | - Jonathan Cheetham
- Cornell University College of Veterinary Medicine, 930 Campus Road, Ithaca, NY, 14853, USA.
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4
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E2F1 Expression and Apoptosis Initiation in Crayfish and Rat Peripheral Neurons and Glial Cells after Axonal Injury. Int J Mol Sci 2022; 23:ijms23084451. [PMID: 35457270 PMCID: PMC9026502 DOI: 10.3390/ijms23084451] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 04/08/2022] [Accepted: 04/13/2022] [Indexed: 02/04/2023] Open
Abstract
Neurotrauma is among the main causes of human disability and mortality. The transcription factor E2F1 is one of the key proteins that determine the fate of cells. The involvement of E2F1 in the regulation of survival and death of peripheral nerve cells after axotomy has not been previously studied. We, for the first time, studied axotomy-induced changes in the expression and localization of E2F1 following axonal injury in rats and crayfish. Immunoblotting and immunofluorescence microscopy were used for the analysis of the expression and intracellular localization of E2F1 and its changes after axotomy. To evaluate whether this transcription factor promotes cell apoptosis, we examined the effect of pharmacological inhibition of E2F activity in axotomized rat models. In this work, axotomy caused increased expression of E2F1 as early as 4 h and even 1 h after axotomy of mechanoreceptor neurons and ganglia of crayfish ventral nerve cord (VNC), as well as rat dorsal root ganglia (DRG). The level of E2F1 expression increased both in the cytoplasm and the nuclei of neurons. Pharmacological inhibition of E2F demonstrated a pronounced neuroprotective activity against axotomized DRGs. E2F1 and downstream targets could be considered promising molecular targets for the development of potential neuroprotective agents.
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5
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Role of Myc Proto-Oncogene as a Transcriptional Hub to Regulate the Expression of Regeneration-Associated Genes following Preconditioning Peripheral Nerve Injury. J Neurosci 2021; 41:446-460. [PMID: 33262248 DOI: 10.1523/jneurosci.1745-20.2020] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 11/16/2020] [Accepted: 11/18/2020] [Indexed: 12/20/2022] Open
Abstract
Preconditioning peripheral nerve injury enhances the intrinsic growth capacity of DRGs sensory axons by inducing transcriptional upregulation of the regeneration-associated genes (RAGs). However, it is still unclear how preconditioning injury leads to the orchestrated induction of many RAGs. The present study identified Myc proto-oncogene as a transcriptional hub gene to regulate the expression of a distinct subset of RAGs in DRGs following the preconditioning injury. We demonstrated that c-MYC bound to the promoters of certain RAGs, such as Jun, Atf3, and Sprr1a, and that Myc upregulation following SNI preceded that of the RAGs bound by c-MYC. Marked DNA methylation of the Myc exon 3 sequences was implicated in the early transcriptional activation and accompanied by open histone marks. Myc deletion led to a decrease in the injury-induced expression of a distinct subset of RAGs, which were highly overlapped with the list of RAGs that were upregulated by Myc overexpression. Following dorsal hemisection spinal cord injury in female rats, Myc overexpression in DRGs significantly prevented the retraction of the sensory axons in a manner dependent on its downstream RAG, June Our results suggest that Myc plays a critical role in axon regeneration via its transcriptional activity to regulate the expression of a spectrum of downstream RAGs and subsequent effector molecules. Identification of more upstream hub transcription factors and the epigenetic mechanisms specific for individual hub transcription factors would advance our understanding of how the preconditioning injury induces orchestrated upregulation of RAGs.
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6
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Loverde JR, Tolentino RE, Soteropoulos P, Pfister BJ. Biomechanical Forces Regulate Gene Transcription During Stretch-Mediated Growth of Mammalian Neurons. Front Neurosci 2021; 14:600136. [PMID: 33408609 PMCID: PMC7780124 DOI: 10.3389/fnins.2020.600136] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 11/11/2020] [Indexed: 11/25/2022] Open
Abstract
At birth, there are 100 billion neurons in the human brain, with functional neural circuits extending through the spine to the epidermis of the feet and toes. Following birth, limbs and vertebrae continue to grow by several orders of magnitude, forcing established axons to grow by up to 200 cm in length without motile growth cones. The leading regulatory paradigm suggests that biomechanical expansion of mitotic tissue exerts tensile force on integrated nervous tissue, which synchronizes ongoing growth of spanning axons. Here, we identify unique transcriptional changes in embryonic rat DRG and cortical neurons while the corresponding axons undergo physiological levels of controlled mechanical stretch in vitro. Using bioreactors containing cultured neurons, we recapitulated the peak biomechanical increase in embryonic rat crown-rump-length. Biologically paired sham and “stretch-grown” DRG neurons spanned 4.6- and 17.2-mm in length following static or stretch-induced growth conditions, respectively, which was associated with 456 significant changes in gene transcription identified by genome-wide cDNA microarrays. Eight significant genes found in DRG were cross-validated in stretch-grown cortical neurons by qRT-PCR, which included upregulation of Gpat3, Crem, Hmox1, Hpse, Mt1a, Nefm, Sprr1b, and downregulation of Nrep. The results herein establish a link between biomechanics and gene transcription in mammalian neurons, which elucidates the mechanism underlying long-term growth of axons, and provides a basis for new research in therapeutic axon regeneration.
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Affiliation(s)
- Joseph R Loverde
- Department of Biomedical Engineering, Center for Injury Biomechanics, Materials, and Medicine, New Jersey Institute of Technology, Newark, NJ, United States
| | - Rosa E Tolentino
- Department of Biomedical Engineering, Center for Injury Biomechanics, Materials, and Medicine, New Jersey Institute of Technology, Newark, NJ, United States
| | - Patricia Soteropoulos
- Department of Microbiology, Biochemistry and Molecular Genetics, Genomics Center, Rutgers New Jersey Medical School, Rutgers University, Newark, NJ, United States
| | - Bryan J Pfister
- Department of Biomedical Engineering, Center for Injury Biomechanics, Materials, and Medicine, New Jersey Institute of Technology, Newark, NJ, United States
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7
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Kalinski AL, Yoon C, Huffman LD, Duncker PC, Kohen R, Passino R, Hafner H, Johnson C, Kawaguchi R, Carbajal KS, Jara JS, Hollis E, Geschwind DH, Segal BM, Giger RJ. Analysis of the immune response to sciatic nerve injury identifies efferocytosis as a key mechanism of nerve debridement. eLife 2020; 9:60223. [PMID: 33263277 PMCID: PMC7735761 DOI: 10.7554/elife.60223] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 12/01/2020] [Indexed: 12/12/2022] Open
Abstract
Sciatic nerve crush injury triggers sterile inflammation within the distal nerve and axotomized dorsal root ganglia (DRGs). Granulocytes and pro-inflammatory Ly6Chigh monocytes infiltrate the nerve first and rapidly give way to Ly6Cnegative inflammation-resolving macrophages. In axotomized DRGs, few hematogenous leukocytes are detected and resident macrophages acquire a ramified morphology. Single-cell RNA-sequencing of injured sciatic nerve identifies five macrophage subpopulations, repair Schwann cells, and mesenchymal precursor cells. Macrophages at the nerve crush site are molecularly distinct from macrophages associated with Wallerian degeneration. In the injured nerve, macrophages ‘eat’ apoptotic leukocytes, a process called efferocytosis, and thereby promote an anti-inflammatory milieu. Myeloid cells in the injured nerve, but not axotomized DRGs, strongly express receptors for the cytokine GM-CSF. In GM-CSF-deficient (Csf2-/-) mice, inflammation resolution is delayed and conditioning-lesion-induced regeneration of DRG neuron central axons is abolished. Thus, carefully orchestrated inflammation resolution in the nerve is required for conditioning-lesion-induced neurorepair.
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Affiliation(s)
- Ashley L Kalinski
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States
| | - Choya Yoon
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States
| | - Lucas D Huffman
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States.,Neuroscience Graduate Program, University of Michigan Medical School, Ann Arbor, United States
| | - Patrick C Duncker
- Department of Neurology, University of Michigan Medical School, Ann Arbor, United States
| | - Rafi Kohen
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States.,Neuroscience Graduate Program, University of Michigan Medical School, Ann Arbor, United States
| | - Ryan Passino
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States
| | - Hannah Hafner
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States
| | - Craig Johnson
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States
| | - Riki Kawaguchi
- Program in Neurogenetics, Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Kevin S Carbajal
- Department of Neurology, University of Michigan Medical School, Ann Arbor, United States
| | | | - Edmund Hollis
- Burke Neurological Institute, White Plains, United States.,The Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, United States
| | - Daniel H Geschwind
- Program in Neurogenetics, Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Benjamin M Segal
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, United States.,The Neurological Institute, The Ohio State University, Columbus, United States
| | - Roman J Giger
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States.,Neuroscience Graduate Program, University of Michigan Medical School, Ann Arbor, United States.,Department of Neurology, University of Michigan Medical School, Ann Arbor, United States
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8
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Senger JL, Chan KM, Macandili H, Chan AWM, Verge VMK, Jones KE, Webber CA. Conditioning electrical stimulation promotes functional nerve regeneration. Exp Neurol 2019; 315:60-71. [PMID: 30731076 DOI: 10.1016/j.expneurol.2019.02.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Revised: 01/30/2019] [Accepted: 02/01/2019] [Indexed: 12/11/2022]
Abstract
Peripheral nerve regeneration following injury is often incomplete, resulting in significant personal and socioeconomic costs. Although a conditioning crush lesion prior to surgical nerve transection and repair greatly promotes nerve regeneration and functional recovery, feasibility and ethical considerations have hindered its clinical applicability. In a recent proof of principle study, we demonstrated that conditioning electrical stimulation (CES) had effects on early nerve regeneration, similar to that seen in conditioning crush lesions (CCL). To convincingly determine its clinical utility, establishing the effects of CES on target reinnervation and functional outcomes is of utmost importance. In this study, we found that CES improved nerve regeneration and reinnervation well beyond that of CCL. Specifically, compared to CCL, CES resulted in greater intraepidermal skin and NMJ reinnervation, and greater physiological and functional recovery including mechanosensation, compound muscle action potential on nerve conduction studies, normalization of gait pattern, and motor performance on the horizontal ladder test. These findings have direct clinical relevance as CES could be delivered at the bedside before scheduled nerve surgery.
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Affiliation(s)
- Jenna-Lynn Senger
- Department of Surgery, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - K Ming Chan
- Division of Physical Rehabilitation, University of Alberta, Edmonton, AB T6G 2G3, Canada
| | - Haecy Macandili
- Department of Surgery, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Ashley W M Chan
- Department of Surgery, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Valerie M K Verge
- Department of Anatomy and Cell Biology, Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, SK S7K 0M7, Canada
| | - Kelvin E Jones
- Department of Biomedical Engineering, University of Alberta, Edmonton, AB T6G 2H9, Canada
| | - Christine A Webber
- Department of Surgery, University of Alberta, Edmonton, AB T6G 2H7, Canada.
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9
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Raoofi A, Abdollahifar MA, Aliaghaei A, Piryaei A, Hejazi F, Sajadi E, Rashidiani-Rashidabadi A, Sadeghi Y. Peripheral axotomy-induced changes of motor function and histological structure of spinal anterior horn. Eur J Transl Myol 2019; 29:7945. [PMID: 31019660 PMCID: PMC6460218 DOI: 10.4081/ejtm.2019.7945] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 12/17/2018] [Indexed: 01/09/2023] Open
Abstract
The aim of this study was to evaluate changes of both peripheral motor function and histology of spinal anterior horn in adult rats after unilateral sciatectomy. Ten adult healthy rats served as control group, while in the ten rat experimental group the right sciatic nerve was severed. We followed-up nerve motor function using a sciatic function index and electromyography activity of the gastrocnemious muscle. The rats of the experimental group presented the expected gross locomotor deficit and leg muscle atrophy. At 12 weeks post sciatectomy, L4 and L5 spinal cord segments were removed from the twenty rats and were analysed by istological stereological methods. In the axotomized animals volume of the anterior horn and its content of motor neurons decreased, while the content of astrocytes increased (p < 0.05). Thus, in adult rats, beside the obvious peripheral nerve disfuction, the sciatic nerve axotomy have severe consequences on the soma of the injured motor neurons in the spinal anterior horn. All these quantitative analyses may be usefull to quantify changes occurring in adult animals after axotomy and eventual management to modify the final outcomes in peripheral nerve disorders.
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Affiliation(s)
- Amir Raoofi
- Department of Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammad Amin Abdollahifar
- Department of Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Abbas Aliaghaei
- Department of Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Abbas Piryaei
- Department of Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Fatemeh Hejazi
- Department of Polymer Engineering and Color Technology, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran
| | - Ensieh Sajadi
- Department of Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Ali Rashidiani-Rashidabadi
- Department of Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Yousef Sadeghi
- Department of Biology and Anatomical Sciences, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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10
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Senger JLB, Verge VMK, Chan KM, Webber CA. The nerve conditioning lesion: A strategy to enhance nerve regeneration. Ann Neurol 2018. [DOI: 10.1002/ana.25209] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
| | - Valerie M. K. Verge
- Department of Anatomy and Cell Biology, and Cameco MS Neuroscience Research Center; University of Saskatchewan; Saskatoon Saskatchewan
| | - K. Ming Chan
- Department of Physical Rehabilitation; University of Alberta; Edmonton Alberta Canada
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11
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Affiliation(s)
- Xuenong Bo
- Centre for Neuroscience and Trauma, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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12
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Senger JLB, Verge VMK, Macandili HSJ, Olson JL, Chan KM, Webber CA. Electrical stimulation as a conditioning strategy for promoting and accelerating peripheral nerve regeneration. Exp Neurol 2017; 302:75-84. [PMID: 29291403 DOI: 10.1016/j.expneurol.2017.12.013] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 12/23/2017] [Accepted: 12/26/2017] [Indexed: 02/07/2023]
Abstract
The delivery of a nerve insult (a "conditioning lesion") prior to a subsequent test lesion increases the number of regenerating axons and accelerates the speed of regeneration from the test site. A major barrier to clinical translation is the lack of an ethically acceptable and clinically feasible method of conditioning that does not further damage the nerve. Conditioning electrical stimulation (CES), a non-injurious intervention, has previously been shown to improve neurite outgrowth in vitro. In this study, we examined whether CES upregulates regeneration-associated gene (RAG) expression and promotes nerve regeneration in vivo, similar to a traditional nerve crush conditioning lesion (CCL). Adult rats were divided into four cohorts based on conditioning treatment to the common peroneal (fibular) nerve: i) CES (1h, 20Hz); ii) CCL (10s crush); iii) sham CES (1h, 0Hz); or iv) naïve (unconditioned). Immunofluorescence and qRT-PCR revealed significant RAG upregulation in the dorsal root ganglia of both CES and CCL animals, evident at 3-14days post-conditioning. To mimic a clinical microsurgical nerve repair, all cohorts underwent a common peroneal nerve cut and coaptation one week following conditioning. Both CES and CCL animals increased the length of nerve regeneration (3.8-fold) as well as the total number of regenerating axons (2.2-fold), compared to the sham and naïve-conditioned animals (p<0.001). These data support CES as a non-injurious conditioning paradigm that is comparable to a traditional CCL and is therefore a novel means to potentially enhance peripheral nerve repair in the clinical setting.
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Affiliation(s)
- J L B Senger
- Department of Surgery, University of Alberta, Alberta, Canada
| | - V M K Verge
- Department of Anatomy and Cell Biology & Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatchewan, Canada
| | - H S J Macandili
- Department of Surgery, University of Alberta, Alberta, Canada
| | - J L Olson
- Department of Surgery, University of Alberta, Alberta, Canada
| | - K M Chan
- Division of Physical Medicine and Rehabilitation, University of Alberta, Alberta, Canada
| | - C A Webber
- Department of Surgery, University of Alberta, Alberta, Canada.
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13
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Intraneural Injection of ATP Stimulates Regeneration of Primary Sensory Axons in the Spinal Cord. J Neurosci 2017; 38:1351-1365. [PMID: 29279307 PMCID: PMC5815342 DOI: 10.1523/jneurosci.1660-17.2017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 11/06/2017] [Accepted: 11/09/2017] [Indexed: 12/17/2022] Open
Abstract
Injury to the peripheral axons of sensory neurons strongly enhances the regeneration of their central axons in the spinal cord. It remains unclear on what molecules that initiate such conditioning effect. Because ATP is released extracellularly by nerve and other tissue injury, we hypothesize that injection of ATP into a peripheral nerve might mimic the stimulatory effect of nerve injury on the regenerative state of the primary sensory neurons. We found that a single injection of 6 μl of 150 μm ATP into female rat sciatic nerve quadrupled the number of axons growing into a lesion epicenter in spinal cord after a concomitant dorsal column transection. A second boost ATP injection 1 week after the first one markedly reinforced the stimulatory effect of a single injection. Single ATP injection increased expression of phospho-STAT3 and GAP43, two markers of regenerative activity, in sensory neurons. Double ATP injections sustained the activation of phospho-STAT3 and GAP43, which may account for the marked axonal growth across the lesion epicenter. Similar studies performed on P2X7 or P2Y2 receptor knock-out mice indicate P2Y2 receptors are involved in the activation of STAT3 after ATP injection or conditioning lesion, whereas P2X7 receptors are not. Injection of ATP at 150 μm caused little Wallerian degeneration and behavioral tests showed no significant long-term adverse effects on sciatic nerve functions. The results in this study reveal possible mechanisms underlying the stimulation of regenerative programs and suggest a practical strategy for stimulating axonal regeneration following spinal cord injury. SIGNIFICANCE STATEMENT Injury of peripheral axons of sensory neurons has been known to strongly enhance the regeneration of their central axons in the spinal cord. In this study, we found that injection of ATP into a peripheral nerve can mimic the effect of peripheral nerve injury and significantly increase the number of sensory axons growing across lesion epicenter in the spinal cord. ATP injection increased expression of several markers for regenerative activity in sensory neurons, including phospho-STAT3 and GAP43. ATP injection did not cause significant long-term adverse effects on the functions of the injected nerve. These results may lead to clinically applicable strategies for enhancing neuronal responses that support regeneration of injured axons.
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14
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Preferential Enhancement of Sensory and Motor Axon Regeneration by Combining Extracellular Matrix Components with Neurotrophic Factors. Int J Mol Sci 2016; 18:ijms18010065. [PMID: 28036084 PMCID: PMC5297700 DOI: 10.3390/ijms18010065] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 11/28/2016] [Accepted: 12/24/2016] [Indexed: 11/29/2022] Open
Abstract
After peripheral nerve injury, motor and sensory axons are able to regenerate but inaccuracy of target reinnervation leads to poor functional recovery. Extracellular matrix (ECM) components and neurotrophic factors (NTFs) exert their effect on different neuronal populations creating a suitable environment to promote axonal growth. Here, we assessed in vitro and in vivo the selective effects of combining different ECM components with NTFs on motor and sensory axons regeneration and target reinnervation. Organotypic cultures with collagen, laminin and nerve growth factor (NGF)/neurotrophin-3 (NT3) or collagen, fibronectin and brain-derived neurotrophic factor (BDNF) selectively enhanced sensory neurite outgrowth of DRG neurons and motor neurite outgrowth from spinal cord slices respectively. For in vivo studies, the rat sciatic nerve was transected and repaired with a silicone tube filled with a collagen and laminin matrix with NGF/NT3 encapsulated in poly(lactic-co-glycolic acid) (PLGA) microspheres (MP) (LM + MP.NGF/NT3), or a collagen and fibronectin matrix with BDNF in PLGA MPs (FN + MP.BDNF). Retrograde labeling and functional tests showed that LM + MP.NGF/NT3 increased the number of regenerated sensory neurons and improved sensory functional recovery, whereas FN + MP.BDNF preferentially increased regenerated motoneurons and enhanced motor functional recovery. Therefore, combination of ECM molecules with NTFs may be a good approach to selectively enhance motor and sensory axons regeneration and promote appropriate target reinnervation.
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Law V, Dong S, Rosales JL, Jeong MY, Zochodne D, Lee KY. Enhancement of Peripheral Nerve Regrowth by the Purine Nucleoside Analog and Cell Cycle Inhibitor, Roscovitine. Front Cell Neurosci 2016; 10:238. [PMID: 27799897 PMCID: PMC5066473 DOI: 10.3389/fncel.2016.00238] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 09/30/2016] [Indexed: 02/03/2023] Open
Abstract
Peripheral nerve regeneration is a slow process that can be associated with limited outcomes and thus a search for novel and effective therapy for peripheral nerve injury and disease is crucial. Here, we found that roscovitine, a synthetic purine nucleoside analog, enhances neurite outgrowth in neuronal-like PC12 cells. Furthermore, ex vivo analysis of pre-injured adult rat dorsal root ganglion (DRG) neurons showed that roscovitine enhances neurite regrowth in these cells. Likewise, in vivo transected sciatic nerves in rats locally perfused with roscovitine had augmented repopulation of new myelinated axons beyond the transection zone. By mass spectrometry, we found that roscovitine interacts with tubulin and actin. It interacts directly with tubulin and causes a dose-dependent induction of tubulin polymerization as well as enhances Guanosine-5′-triphosphate (GTP)-dependent tubulin polymerization. Conversely, roscovitine interacts indirectly with actin and counteracts the inhibitory effect of cyclin-dependent kinases 5 (Cdk5) on Actin-Related Proteins 2/3 (Arp2/3)-dependent actin polymerization, and thus, causes actin polymerization. Moreover, in the presence of neurotrophic factors such as nerve growth factor (NGF), roscovitine-enhanced neurite outgrowth is mediated by increased activation of the extracellular signal-regulated kinases 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK) pathways. Since microtubule and F-actin dynamics are critical for axonal regrowth, the ability of roscovitine to activate the ERK1/2 and p38 MAPK pathways and support polymerization of tubulin and actin indicate a major role for this purine nucleoside analog in the promotion of axonal regeneration. Together, our findings demonstrate a therapeutic potential for the purine nucleoside analog, roscovitine, in peripheral nerve injury.
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Affiliation(s)
- Vincent Law
- Department of Cell Biology and Anatomy, Arnie Charbonneau Cancer Institute, Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada
| | - Sophie Dong
- Department of Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada
| | - Jesusa L Rosales
- Department of Biochemistry and Molecular Biology, Snyder Institute for Chronic Diseases, University of Calgary Calgary, AB, Canada
| | - Myung-Yung Jeong
- Department of Cogno-Mechatronics Engineering, Pusan National University Pusan, South Korea
| | - Douglas Zochodne
- Department of Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada
| | - Ki-Young Lee
- Department of Cell Biology and Anatomy, Arnie Charbonneau Cancer Institute, Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada
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Khaitin AM, Rudkovskii MV, Uzdensky AB. The method of isolation of the crayfish abdominal stretch receptor maintaining a connection of the sensory neuron to the ventral nerve cord ganglion. INVERTEBRATE NEUROSCIENCE 2014; 15:176. [DOI: 10.1007/s10158-014-0176-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2014] [Accepted: 10/10/2014] [Indexed: 11/30/2022]
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Barton MJ, Morley JW, Stoodley MA, Lauto A, Mahns DA. Nerve repair: toward a sutureless approach. Neurosurg Rev 2014; 37:585-95. [PMID: 25015388 DOI: 10.1007/s10143-014-0559-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 02/04/2014] [Accepted: 04/13/2014] [Indexed: 12/16/2022]
Abstract
Peripheral nerve repair for complete section injuries employ reconstructive techniques that invariably require sutures in their application. Sutures are unable to seal the nerve, thus incapable of preventing leakage of important intraneural fluids from the regenerating nerve. Furthermore, sutures are technically demanding to apply for direct repairs and often induce detrimental scarring that impedes healing and functional recovery. To overcome these limitations, biocompatible and biodegradable glues have been used to seal and repair peripheral nerves. Although creating a sufficient seal, they can lack flexibility and present infection risks or cytotoxicity. Other adhesive biomaterials have recently emerged into practice that are usually based on proteins such as albumin and collagen or polysaccharides like chitosan. These adhesives form their union to nerve tissue by either photothermal (tissue welding) or photochemical (tissue bonding) activation with laser light. These biomaterial adhesives offer significant advantages over sutures, such as their capacity to unite and seal the epineurium, ease of application, reduced invasiveness and add the potential for drug delivery in situ to facilitate regeneration. This paper reviews a number of different peripheral nerve repair (or reconstructive) techniques currently used clinically and in experimental procedures for nerve injuries with or without tissue deficit.
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Affiliation(s)
- Matthew J Barton
- Griffith Health Institute, Griffith University, Gold Coast Campus, Queensland, 4222, Australia,
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Wong WK, Cheung AWS, Yu SW, Sha O, Cho EYP. Hepatocyte growth factor promotes long-term survival and axonal regeneration of retinal ganglion cells after optic nerve injury: comparison with CNTF and BDNF. CNS Neurosci Ther 2014; 20:916-29. [PMID: 24992648 DOI: 10.1111/cns.12304] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 06/02/2014] [Accepted: 06/04/2014] [Indexed: 11/29/2022] Open
Abstract
AIMS Different trophic factors are known to promote retinal ganglion cell survival and regeneration, but each had their own limitations. We report that hepatocyte growth factor (HGF) confers distinct advantages in supporting ganglion cell survival and axonal regeneration, when compared to two well-established trophic factors ciliary neurotrophic factor (CNTF) and brain-derived neurotrophic factor (BDNF). METHODS Ganglion cells in adult hamster were injured by cutting the optic nerve. HGF, CNTF, or BDNF was injected at different dosages intravitreally after injury. Ganglion cell survival was quantified at 7, 14, or 28 days postinjury. Peripheral nerve (PN) grafting to the cut optic nerve of the growth factor-injected eye was performed either immediately after injury or delayed until 7 days post-injury. Expression of heat-shock protein 27 and changes in microglia numbers were quantified in different growth factor groups. The cellular distribution of c-Met in the retina was examined by anti-c-Met immunostaining. RESULTS Hepatocyte Growth Factor (HGF) was equally potent as BDNF in promoting short-term survival (up to 14 days post-injury) and also supported survival at 28 days post-injury when ganglion cells treated by CNTF or BDNF failed to be sustained. When grafting was performed without delay, HGF stimulated twice the number of axons to regenerate compared with control but was less potent than CNTF. However, in PN grafting delayed for 7 days after optic nerve injury, HGF maintained a better propensity of ganglion cells to regenerate than CNTF. Unlike CNTF, HGF application did not increase HSP27 expression in ganglion cells. Microglia proliferation was prolonged in HGF-treated retinas compared with CNTF or BDNF. C-Met was localized to both ganglion cells and Muller cells, suggesting HGF could be neuroprotective via interacting with both neurons and glia. CONCLUSION Compared with CNTF or BDNF, HGF is advantageous in sustaining long-term ganglion cell survival and their propensity to respond to favorable stimuli.
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Affiliation(s)
- Wai-Kai Wong
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China
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Neurotrophins and nerve regeneration-associated genes are expressed in the cornea after lamellar flap surgery. Cornea 2013; 31:1460-7. [PMID: 22673847 DOI: 10.1097/ico.0b013e318247b60e] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
PURPOSE To determine the in vivo expression of neurotrophins (NTs) and nerve regeneration-associated genes (RAGs) after surgically creating a hinged lamellar corneal flap in thy1-YFP mice. METHODS Lamellar corneal flaps with multiple hinges were created in thy1-YFP mice. Mice were killed at weeks 2, 4, and 8. Quantitative polymerase chain reaction was performed to determine the expression of NTs and RAGs in the corneas after lamellar transection. Nerve growth factor (Ngf), brain-derived neurotrophic factor (Bdnf), glial cell-derived neurotrophic factor (Gdnf), neurotrophin 3, neurotrophin 5, small proline-rich repeat protein 1A (Sprr1a), growth-associated protein 43 (Gap43), and beta III tubulin (Tubb3) gene expressions were analyzed. Whole-mount confocal immunofluorescence and Western analyses were performed for localization and abundance of robustly expressed genes. RESULTS Sprouts of fine YFP-positive fronds emanating from transected (injured) nerve bundles were seen in the flap area at 2 weeks onward. Bdnf and Sprr1a were robustly and significantly expressed at 2 weeks postoperatively (>2-fold increase in expression; P<0.05). Bdnf localized to thy1-YFP+ cells in operated corneas. Sprr1a localized to corneal epithelial cell membranes. At 8 weeks, none of the NTs and RAGs had increased expression. Bdnf (ρ=0.73, P=0.001) and Sprr1a (ρ=0.76, P=0.001) showed a significant positive correlation with beta III tubulin. CONCLUSIONS The neurotrophin Bdnf and RAG Sprr1a are robustly and significantly expressed during corneal nerve regeneration in vivo.
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Toll EC, Seifalian AM, Birchall MA. The role of immunophilin ligands in nerve regeneration. Regen Med 2012; 6:635-52. [PMID: 21916598 DOI: 10.2217/rme.11.43] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Tacrolimus (FK506) is a widely used immunosuppressant in organ transplantation. However, it also has neurotrophic activity that occurs independently of its immunosuppressive effects. Other neurotrophic immunophilin ligands that do not exhibit immunosuppression have subsequently been developed and studied in various models of nerve injury. This article reviews the literature on the use of tacrolimus and other immunophilin ligands in peripheral nerve, cranial nerve and spinal cord injuries. The most convincing evidence of enhanced nerve regeneration is seen with systemic administration of tacrolimus in peripheral nerve injury, although clinical use is limited due to its immunosuppressive side effects. Local tacrolimus delivery to the site of nerve repair in peripheral and cranial nerve injury is less effective but requires further investigation. Tacrolimus can enhance outcomes in nerve allograft reconstruction and accelerates reinnervation of complex functional allograft transplants. Other non-immunosuppressive immunophilins ligands such as V-10367 and FK1706 demonstrate enhanced neuroregeneration in the peripheral nervous system and CNS. Mixed results are found in the application of immunophilin ligands to treat spinal cord injury. Immunophilin ligands have great potential in the treatment of nerve injury, but further preclinical studies are necessary to permit translation into clinical trials.
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Affiliation(s)
- Edward C Toll
- Division of Surgery and Interventional Science, University College London, UK.
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Ghannad-Rezaie M, Wang X, Mishra B, Collins C, Chronis N. Microfluidic chips for in vivo imaging of cellular responses to neural injury in Drosophila larvae. PLoS One 2012; 7:e29869. [PMID: 22291895 PMCID: PMC3264548 DOI: 10.1371/journal.pone.0029869] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2011] [Accepted: 12/05/2011] [Indexed: 12/17/2022] Open
Abstract
With powerful genetics and a translucent cuticle, the Drosophila larva is an ideal model system for live imaging studies of neuronal cell biology and function. Here, we present an easy-to-use approach for high resolution live imaging in Drosophila using microfluidic chips. Two different designs allow for non-invasive and chemical-free immobilization of 3rd instar larvae over short (up to 1 hour) and long (up to 10 hours) time periods. We utilized these ‘larva chips’ to characterize several sub-cellular responses to axotomy which occur over a range of time scales in intact, unanaesthetized animals. These include waves of calcium which are induced within seconds of axotomy, and the intracellular transport of vesicles whose rate and flux within axons changes dramatically within 3 hours of axotomy. Axonal transport halts throughout the entire distal stump, but increases in the proximal stump. These responses precede the degeneration of the distal stump and regenerative sprouting of the proximal stump, which is initiated after a 7 hour period of dormancy and is associated with a dramatic increase in F-actin dynamics. In addition to allowing for the study of axonal regeneration in vivo, the larva chips can be utilized for a wide variety of in vivo imaging applications in Drosophila.
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Affiliation(s)
- Mostafa Ghannad-Rezaie
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Xing Wang
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Bibhudatta Mishra
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Catherine Collins
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail: (NC); (CC)
| | - Nikos Chronis
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail: (NC); (CC)
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Abstract
Failure of axon regeneration after central nervous system (CNS) injuries results in permanent functional deficits. Numerous studies in the past suggested that blocking extracellular inhibitory influences alone is insufficient to allow the majority of injured axons to regenerate, pointing to the importance of revisiting the hypothesis that diminished intrinsic regenerative ability critically underlies regeneration failure. Recent studies in different species and using different injury models have started to reveal important cellular and molecular mechanisms within neurons that govern axon regeneration. This review summarizes these observations and discusses possible strategies for stimulating axon regeneration and perhaps functional recovery after CNS injury.
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Affiliation(s)
- Kai Liu
- FM Kirby Neurobiology Center, Children's Hospital, and Department of Neurology, Harvard Medical School, Boston, Massachusetts 02115, USA
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Diffuse traumatic axonal injury in the mouse induces atrophy, c-Jun activation, and axonal outgrowth in the axotomized neuronal population. J Neurosci 2011; 31:5089-105. [PMID: 21451046 DOI: 10.1523/jneurosci.5103-10.2011] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Traumatic axonal injury (TAI) is a consistent component of traumatic brain injury (TBI) and is associated with much of its morbidity. Little is known regarding the long-term retrograde neuronal consequences of TAI and/or the potential that TAI could lead to anterograde axonal reorganization and repair. To investigate the repertoire of anterograde and retrograde responses triggered by TIA, Thy1-YFP-H mice were subjected to mild central fluid percussion injury and killed at various times between 15 min and 28 d post-injury. Based upon confocal assessment of the endogenous neuronal fluorescence, such injury was found to result in diffuse TAI throughout layer V of the neocortex within yellow fluorescent protein (YFP)-positive axons. When these fluorescent approaches were coupled with various quantitative and immunohistochemical approaches, we found that this TAI did not result in neuronal death over the 28 d period assessed. Rather, it elicited neuronal atrophy. Within these same axotomized neuronal populations, TAI was also found to induce an early and sustained activation of the transcription factors c-Jun and ATF-3 (activating transcription factor 3), known regulators of axon regeneration. Parallel ultrastructural studies confirmed that these reactive changes are consistent with atrophy in the absence of neuronal death. Concurrent with those events ongoing in the neuronal cell bodies, their downstream axonal segments revealed, as early as 1 d post-injury, morphological changes consistent with reactive sprouting that was accompanied by significant axonal elongation over time. Collectively, these TAI-linked events are consistent with sustained neuronal recovery, an activation of a regenerative genetic program, and subsequent axonal reorganization suggestive of some form of regenerative response.
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Xiong X, Wang X, Ewanek R, Bhat P, Diantonio A, Collins CA. Protein turnover of the Wallenda/DLK kinase regulates a retrograde response to axonal injury. ACTA ACUST UNITED AC 2010; 191:211-23. [PMID: 20921142 PMCID: PMC2953441 DOI: 10.1083/jcb.201006039] [Citation(s) in RCA: 215] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Regenerative responses to axonal injury involve changes in gene expression; however, little is known about how such changes can be induced from a distant site of injury. In this study, we describe a nerve crush assay in Drosophila melanogaster to study injury signaling and regeneration mechanisms. We find that Wallenda (Wnd), a conserved mitogen-activated protein kinase (MAPK) kinase kinase homologous to dual leucine zipper kinase, functions as an upstream mediator of a cell-autonomous injury signaling cascade that involves the c-Jun NH(2)-terminal kinase MAPK and Fos transcription factor. Wnd is physically transported in axons, and axonal transport is required for the injury signaling mechanism. Wnd is regulated by a conserved E3 ubiquitin ligase, named Highwire (Hiw) in Drosophila. Injury induces a rapid increase in Wnd protein concomitantly with a decrease in Hiw protein. In hiw mutants, injury signaling is constitutively active, and neurons initiate a faster regenerative response. Our data suggest that the regulation of Wnd protein turnover by Hiw can function as a damage surveillance mechanism for responding to axonal injury.
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Affiliation(s)
- Xin Xiong
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
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Deumens R, Bozkurt A, Meek MF, Marcus MAE, Joosten EAJ, Weis J, Brook GA. Repairing injured peripheral nerves: Bridging the gap. Prog Neurobiol 2010; 92:245-76. [PMID: 20950667 DOI: 10.1016/j.pneurobio.2010.10.002] [Citation(s) in RCA: 358] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Revised: 09/30/2010] [Accepted: 10/05/2010] [Indexed: 02/06/2023]
Abstract
Peripheral nerve injuries that induce gaps larger than 1-2 cm require bridging strategies for repair. Autologous nerve grafts are still the gold standard for such interventions, although alternative treatments, as well as treatments to improve the therapeutic efficacy of autologous nerve grafting are generating increasing interest. Investigations are still mostly experimental, although some clinical studies have been undertaken. In this review, we aim to describe the developments in bridging technology which aim to replace the autograft. A multi-disciplinary approach is of utmost importance to develop and optimise treatments of the most challenging peripheral nerve injuries.
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Affiliation(s)
- Ronald Deumens
- Department of Anesthesiology, Maastricht University Medical Center, Maastricht, The Netherlands.
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