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Smith TA, Zhou L, Ghergherehchi CL, Mikesh M, Yang CZ, Tucker HO, Allgood J, Bushman JS, Bittner GD. Polyethylene glycol has immunoprotective effects on sciatic allografts, but behavioral recovery and graft tolerance require neurorrhaphy and axonal fusion. Neural Regen Res 2025; 20:1192-1206. [PMID: 38989956 DOI: 10.4103/nrr.nrr-d-23-01220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 02/29/2024] [Indexed: 07/12/2024] Open
Abstract
JOURNAL/nrgr/04.03/01300535-202504000-00033/figure1/v/2024-07-06T104127Z/r/image-tiff Behavioral recovery using (viable) peripheral nerve allografts to repair ablation-type (segmental-loss) peripheral nerve injuries is delayed or poor due to slow and inaccurate axonal regeneration. Furthermore, such peripheral nerve allografts undergo immunological rejection by the host immune system. In contrast, peripheral nerve injuries repaired by polyethylene glycol fusion of peripheral nerve allografts exhibit excellent behavioral recovery within weeks, reduced immune responses, and many axons do not undergo Wallerian degeneration. The relative contribution of neurorrhaphy and polyethylene glycol-fusion of axons versus the effects of polyethylene glycol per se was unknown prior to this study. We hypothesized that polyethylene glycol might have some immune-protective effects, but polyethylene glycol-fusion was necessary to prevent Wallerian degeneration and functional/behavioral recovery. We examined how polyethylene glycol solutions per se affect functional and behavioral recovery and peripheral nerve allograft morphological and immunological responses in the absence of polyethylene glycol-induced axonal fusion. Ablation-type sciatic nerve injuries in outbred Sprague-Dawley rats were repaired according to a modified protocol using the same solutions as polyethylene glycol-fused peripheral nerve allografts, but peripheral nerve allografts were loose-sutured (loose-sutured polyethylene glycol) with an intentional gap of 1-2 mm to prevent fusion by polyethylene glycol of peripheral nerve allograft axons with host axons. Similar to negative control peripheral nerve allografts not treated by polyethylene glycol and in contrast to polyethylene glycol-fused peripheral nerve allografts, animals with loose-sutured polyethylene glycol peripheral nerve allografts exhibited Wallerian degeneration for all axons and myelin degeneration by 7 days postoperatively and did not recover sciatic-mediated behavioral functions by 42 days postoperatively. Other morphological signs of rejection, such as collapsed Schwann cell basal lamina tubes, were absent in polyethylene glycol-fused peripheral nerve allografts but commonly observed in negative control and loose-sutured polyethylene glycol peripheral nerve allografts at 21 days postoperatively. Loose-sutured polyethylene glycol peripheral nerve allografts had more pro-inflammatory and less anti-inflammatory macrophages than negative control peripheral nerve allografts. While T cell counts were similarly high in loose-sutured-polyethylene glycol and negative control peripheral nerve allografts, loose-sutured polyethylene glycol peripheral nerve allografts expressed some cytokines/chemokines important for T cell activation at much lower levels at 14 days postoperatively. MHCI expression was elevated in loose-sutured polyethylene glycol peripheral nerve allografts, but MHCII expression was modestly lower compared to negative control at 21 days postoperatively. We conclude that, while polyethylene glycol per se reduces some immune responses of peripheral nerve allografts, successful polyethylene glycol-fusion repair of some axons is necessary to prevent Wallerian degeneration of those axons and immune rejection of peripheral nerve allografts, and produce recovery of sensory/motor functions and voluntary behaviors. Translation of polyethylene glycol-fusion technologies would produce a paradigm shift from the current clinical practice of waiting days to months to repair ablation peripheral nerve injuries.
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Affiliation(s)
- Tyler A Smith
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | - Liwen Zhou
- Department of Neuroscience, University of Texas at Austin, Austin, TX, USA
| | | | - Michelle Mikesh
- Department of Neuroscience, University of Texas at Austin, Austin, TX, USA
| | - Cathy Z Yang
- Department of Neuroscience, University of Texas at Austin, Austin, TX, USA
| | - Haley O Tucker
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | - JuliAnne Allgood
- Division of Pharmaceutical Sciences, University of Wyoming, Laramie, WY, USA
| | - Jared S Bushman
- Division of Pharmaceutical Sciences, University of Wyoming, Laramie, WY, USA
| | - George D Bittner
- Department of Neuroscience, University of Texas at Austin, Austin, TX, USA
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Bittner GD, Tuffaha S, Shores JT. Polyethylene Glycol-Fusion Repair of Peripheral Nerve Injuries. Hand Clin 2024; 40:389-397. [PMID: 38972683 DOI: 10.1016/j.hcl.2024.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 07/09/2024]
Abstract
Axons successfully repaired with polyethylene glycol (PEG) fusion tecnology restored axonal continuity thereby preventing their Wallerian degeneration and minimizing muscle atrophy. PEG fusion studies in animal models and preliminary clinical trials involving patients with digital nerve repair have shown promise for this therapeutic approach. PEG fusion is safe to perform, and given the enormous potential benefits, there is no reason not to explore its therapeutic potential.
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Affiliation(s)
- George D Bittner
- Neuroscience Department, Patterson Laboratories, The University of Texas at Austin, Room 321, 2415 Speedway, Austin, TX 78712, USA.
| | - Sami Tuffaha
- Plastic and Reconstructive Surgery, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Jaimie T Shores
- Plastic & Reconstructive Surgery, Johns Hopkins University School of Medicine, 4940 Eastern Avenue, Suite A513, Baltimore, MD 21224, USA
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Acharya N, Acharya AM, Bhat AK, Upadhya D, Punja D, Suhani S. The outcome of polyethylene glycol fusion augmented by electrical stimulation in a delayed setting of nerve repair following neurotmesis in a rat model. Acta Neurochir (Wien) 2023; 165:3993-4002. [PMID: 37907766 PMCID: PMC10739326 DOI: 10.1007/s00701-023-05854-6] [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: 07/06/2023] [Accepted: 10/10/2023] [Indexed: 11/02/2023]
Abstract
PURPOSE Polyethylene glycol is known to improve recovery following its use in repair of acute peripheral nerve injury. The duration till which PEG works remains a subject of intense research. We studied the effect of PEG with augmentation of 20Htz of electrical stimulation (ES) following neurorrhaphy at 48 h in a rodent sciatic nerve neurotmesis model. METHOD Twenty-four Sprague Dawley rats were divided into 4 groups. In group I, the sciatic nerve was transected and repaired immediately. In group II, PEG fusion was done additionally after acute repair. In group III, repair and PEG fusion were done at 48 h. In group IV, ES of 20Htz at 2 mA for 1 h was added to the steps followed for group III. Weekly assessment of sciatic functional index (SFI), pinprick, and cold allodynia tests were done at 3 weeks and euthanized. Sciatic nerve axonal count and muscle weight were done. RESULTS Groups II, III, and IV showed significantly better recovery of SFI (II: 70.10 ± 1.24/III: 84.00 ± 2.59/IV: 74.40 ± 1.71 vs I: 90.00 ± 1.38) (p < 0.001) and axonal counts (II: 4040 ± 270/III: 2121 ± 450/IV:2380 ± 158 vs I: 1024 ± 094) (p < 0.001) at 3 weeks. The experimental groups showed earlier recovery of sensation in comparison to the controls as demonstrated by pinprick and cold allodynia tests and improved muscle weights. Addition of electrical stimulation helped in better score with SFI (III: 84.00 ± 2.59 vs IV: 74.40 ± 1.71) (p < 0.001) and muscle weight (plantar flexors) (III: 0.49 ± 0.02 vs IV: 0.55 ± 0.01) (p < 0.001) in delayed repair and PEG fusions. CONCLUSION This study shows that PEG fusion of peripheral nerve repair in augmentation with ES results in better outcomes, and this benefit can be demonstrated up to a window period of 48 h after injury.
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Affiliation(s)
- Nanda Acharya
- Department of Physiology, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India, 576104
| | - A M Acharya
- Department of Hand Surgery, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India, 576104
| | - Anil K Bhat
- Department of Hand Surgery, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India, 576104.
| | - Dinesh Upadhya
- Centre for Molecular Neurosciences, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India, 576104
| | - Dhiren Punja
- Department of Physiology, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India, 576104
| | - Sumalatha Suhani
- Department of Anatomy, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India, 576104
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Lopez S, Bittner GD, Treviño RC. Rapid and effective fusion repair of severed digital nerves using neurorrhaphy and bioengineered solutions including polyethylene glycol: A case report. Front Cell Neurosci 2023; 16:1087961. [PMID: 36744063 PMCID: PMC9892895 DOI: 10.3389/fncel.2022.1087961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 12/20/2022] [Indexed: 01/20/2023] Open
Abstract
Peripheral nerve injuries (PNIs) that consist of simple nerve severance often result in severe motor impairment and permanent loss of function. Such patients face significant costs and pose major burdens to healthcare systems. Currently, the most promising surgical technique to achieve the best clinical outcome after such PNIs is immediate primary coaptation of severed nerve ends by microsutures (neurorrhaphy). However, recovery is often poor and delayed for many months due to Wallerian degeneration (WD) and slow (1-2 mm/day) axonal outgrowths from severed proximal axons that may not properly reinnervate denervated afferent/efferent targets that have atrophied. In contrast, recent pre-clinical studies using polyethylene glycol (PEG) to facilitate primary nerve repair have greatly improved the rate and extent of sensory and motor recovery and prevented much WD and muscle atrophy. That is, PEG-fused axons rapidly establish proximal-distal axoplasmic/axolemmal continuity, which do not undergo WD and maintain the structure and function of neuromuscular junction (NMJ). PEG-fused axons rapidly reinnervate denervated NMJs, thereby preventing muscle atrophy associated with monthslong denervation due to slowly regenerating axonal outgrowths. We now describe PEG-mediated fusion repair of a digital nerve in each of two patients presenting with a digital laceration resulting in total loss of sensation. The first patient's tactile perception improved markedly at 3 days postoperatively (PO). Two-point discrimination improved from greater than 10 mm at initial presentation to 4 mm at 11-week PO, and the Semmes-Weinstein monofilament score improved from greater than 6.65 to 2.83 mm, a near-normal level. The second patient had severe PO edema and scar development requiring a hand compression glove and scar massage, which began improving at 11-week PO. The sensory function then improved for 4 months PO, with both two-point discrimination and Semmes-Weinstein scores approaching near-normal levels at the final follow-up. These case study data are consistent with data from animal models. All these data suggest that PEG-fusion technologies could produce a paradigm shift from the current clinical practice of waiting days to months to repair ablation PNIs with autografts, anucleated nerve allografts, or conduits in which the patient outcome is solely dependent upon axon regeneration over months or years.
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Affiliation(s)
| | - George D. Bittner
- Department of Neuroscience, University of Texas at Austin, Austin, TX, United States,*Correspondence: George D. Bittner,
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Ho XY, Coakley S, Amor R, Anggono V, Hilliard MA. The metalloprotease ADM-4/ADAM17 promotes axonal repair. SCIENCE ADVANCES 2022; 8:eabm2882. [PMID: 35294233 PMCID: PMC8926332 DOI: 10.1126/sciadv.abm2882] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 01/25/2022] [Indexed: 05/28/2023]
Abstract
Axonal fusion is an efficient means of repair following axonal transection, whereby the regenerating axon fuses with its own separated axonal fragment to restore neuronal function. Despite being described over 50 years ago, its molecular mechanisms remain poorly understood. Here, we demonstrate that the Caenorhabditis elegans metalloprotease ADM-4, an ortholog of human ADAM17, is essential for axonal fusion. We reveal that animals lacking ADM-4 cannot repair their axons by fusion, and that ADM-4 has a cell-autonomous function within injured neurons, localizing at the tip of regrowing axon and fusion sites. We demonstrate that ADM-4 overexpression enhances fusion to levels higher than wild type, and that the metalloprotease and phosphatidylserine-binding domains are essential for its function. Last, we show that ADM-4 interacts with and stabilizes the fusogen EFF-1 to allow membranes to merge. Our results uncover a key role for ADM-4 in axonal fusion, exposing a molecular target for axonal repair.
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Affiliation(s)
- Xue Yan Ho
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Sean Coakley
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Rumelo Amor
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Victor Anggono
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Massimo A. Hilliard
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
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Petrov D, Burrell JC, Browne KD, Laimo FA, Roberts SE, Ali ZS, Cullen DK. Neurorrhaphy in Presence of Polyethylene Glycol Enables Immediate Electrophysiological Conduction in Porcine Model of Facial Nerve Injury. Front Surg 2022; 9:811544. [PMID: 35341161 PMCID: PMC8948462 DOI: 10.3389/fsurg.2022.811544] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 01/24/2022] [Indexed: 01/09/2023] Open
Abstract
Facial nerve trauma often leads to disfiguring facial muscle paralysis. Despite several promising advancements, facial nerve repair procedures often do not lead to complete functional recovery. Development of novel repair strategies requires testing in relevant preclinical models that replicate key clinical features. Several studies have reported that fusogens, such as polyethylene glycol (PEG), can improve functional recovery by enabling immediate reconnection of injured axons; however, these findings have yet to be demonstrated in a large animal model. We first describe a porcine model of facial nerve injury and repair, including the relevant anatomy, surgical approach, and naive nerve morphometry. Next, we report positive findings from a proof-of-concept experiment testing whether a neurorrhaphy performed in conjunction with a PEG solution maintained electrophysiological nerve conduction at an acute time point in a large animal model. The buccal branch of the facial nerve was transected and then immediately repaired by direct anastomosis and PEG application. Immediate electrical conduction was recorded in the PEG-fused nerves (n = 9/9), whereas no signal was obtained in a control cohort lacking calcium chelating agent in one step (n = 0/3) and in the no PEG control group (n = 0/5). Nerve histology revealed putative-fused axons across the repair site, whereas no positive signal was observed in the controls. Rapid electrophysiological recovery following nerve fusion in a highly translatable porcine model of nerve injury supports previous studies suggesting neurorrhaphy supplemented with PEG may be a promising strategy for severe nerve injury. While acute PEG-mediated axon conduction is promising, additional work is necessary to determine if physical axon fusion occurs and the longer-term fate of distal axon segments as related to functional recovery.
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Affiliation(s)
- Dmitriy Petrov
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
| | - Justin C. Burrell
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, United States
| | - Kevin D. Browne
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
| | - Franco A. Laimo
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
| | - Sanford E. Roberts
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
| | - Zarina S. Ali
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - D. Kacy Cullen
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, United States
- *Correspondence: D. Kacy Cullen
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Nuelle JAV, Bozynski C, Stoker A. Innovations in Peripheral Nerve Injury: Current Concepts and Emerging Techniques to Improve Recovery. MISSOURI MEDICINE 2022; 119:129-135. [PMID: 36036028 PMCID: PMC9339399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Despite the surgical advances in treatment of peripheral nerve injuries, consistent recovery of function is limited suggesting that a multimodal approach is required to optimize nerve regeneration. This approach should include advanced surgical repair techniques, as well as tissue engineering, cellular therapies, and application of local and systemic modulators of neuroregeneration. Further research is needed to advance these therapies from the laboratory to clinical practice, and to further understand how these treatments and techniques can act in concert to optimize functional nerve regeneration.
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Affiliation(s)
- Julia A V Nuelle
- Department of Orthopaedic Surgery, University of Missouri - Columbia School of Medicine
| | - Chantelle Bozynski
- Thompson Laboratory for Regenerative Orthopaedics, University of Missouri - Columbia, Columbia, Missouri
| | - Aaron Stoker
- Thompson Laboratory for Regenerative Orthopaedics, University of Missouri - Columbia, Columbia, Missouri
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Bittner GD, Bushman JS, Ghergherehchi CL, Roballo KCS, Shores JT, Smith TA. Typical and atypical properties of peripheral nerve allografts enable novel strategies to repair segmental-loss injuries. J Neuroinflammation 2022; 19:60. [PMID: 35227261 PMCID: PMC8886977 DOI: 10.1186/s12974-022-02395-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 01/19/2022] [Indexed: 12/20/2022] Open
Abstract
AbstractWe review data showing that peripheral nerve injuries (PNIs) that involve the loss of a nerve segment are the most common type of traumatic injury to nervous systems. Segmental-loss PNIs have a poor prognosis compared to other injuries, especially when one or more mixed motor/sensory nerves are involved and are typically the major source of disability associated with extremities that have sustained other injuries. Relatively little progress has been made, since the treatment of segmental loss PNIs with cable autografts that are currently the gold standard for repair has slow and incomplete (often non-existent) functional recovery. Viable peripheral nerve allografts (PNAs) to repair segmental-loss PNIs have not been experimentally or clinically useful due to their immunological rejection, Wallerian degeneration (WD) of anucleate donor graft and distal host axons, and slow regeneration of host axons, leading to delayed re-innervation and producing atrophy or degeneration of distal target tissues. However, two significant advances have recently been made using viable PNAs to repair segmental-loss PNIs: (1) hydrogel release of Treg cells that reduce the immunological response and (2) PEG-fusion of donor PNAs that reduce the immune response, reduce and/or suppress much WD, immediately restore axonal conduction across the donor graft and re-innervate many target tissues, and restore much voluntary behavioral functions within weeks, sometimes to levels approaching that of uninjured nerves. We review the rather sparse cellular/biochemical data for rejection of conventional PNAs and their acceptance following Treg hydrogel and PEG-fusion of PNAs, as well as cellular and systemic data for their acceptance and remarkable behavioral recovery in the absence of tissue matching or immune suppression. We also review typical and atypical characteristics of PNAs compared with other types of tissue or organ allografts, problems and potential solutions for PNA use and storage, clinical implications and commercial availability of PNAs, and future possibilities for PNAs to repair segmental-loss PNIs.
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Weiss JB, Phillips CJ, Malin EW, Gorantla VS, Harding JW, Salgar SK. Stem cell, Granulocyte-Colony Stimulating Factor and/or Dihexa to promote limb function recovery in a rat sciatic nerve damage-repair model: Experimental animal studies. Ann Med Surg (Lond) 2021; 71:102917. [PMID: 34703584 PMCID: PMC8524106 DOI: 10.1016/j.amsu.2021.102917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 10/05/2021] [Indexed: 11/04/2022] Open
Abstract
Background Optimizing nerve regeneration and re-innervation of target muscle/s is the key for improved functional recovery following peripheral nerve damage. We investigated whether administration of mesenchymal stem cell (MSC), Granulocyte-Colony Stimulating Factor (G-CSF) and/or Dihexa can improve recovery of limb function following peripheral nerve damage in rat sciatic nerve transection-repair model. Materials and methods There were 10 experimental groups (n = 6–8 rats/group). Bone marrow derived syngeneic MSCs (2 × 106; passage≤6), G-CSF (200–400 μg/kg b.wt.), Dihexa (2–4 mg/kg b.wt.) and/or Vehicle were administered to male Lewis rats locally via hydrogel at the site of nerve repair, systemically (i.v./i.p), and/or to gastrocnemius muscle. The limb sensory and motor functions were assessed at 1–2 week intervals post nerve repair until the study endpoint (16 weeks). Results The sensory function in all nerve boundaries (peroneal, tibial, sural) returned to nearly normal by 8 weeks (Grade 2.7 on a scale of Grade 0–3 [0 = No function; 3 = Normal function]) in all groups combined. The peroneal nerve function recovered quickly with return of function at one week (∼2.0) while sural nerve function recovered rather slowly at four weeks (∼1.0). Motor function at 8–16 weeks post-nerve repair as determined by walking foot print grades significantly (P < 0.05) improved with MSC + G-CSF or MSC + Dihexa administrations into gastrocnemius muscle and mitigated foot flexion contractures. Conclusions These findings demonstrate MSC, G-CSF and Dihexa are promising candidates for adjunct therapies to promote limb functional recovery after surgical nerve repair, and have implications in peripheral nerve injury and limb transplantation. IACUC No.215064. G-CSF in combination with MSCs improved limb function recovery in sciatic nerve transection- repair model. Dihexa in combination with MSC improved limb function recovery in sciatic nerve transection- repair model. Foot flexion contractures were reduced with G-CSF & MSC or Dihexa & MSC administration into target muscle gastrocnemius. MSC, G-CSF or Dihexa combination therapy is attractive, feasible & promising in peripheral nerve injury repair and have implications in limb transplantation. The findings warrant further investigation to understand the cellular/molecular mechanisms.
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Affiliation(s)
- Jessica B Weiss
- Department of Surgery, Madigan Army Medical Center, Tacoma, Fort Lewis, Washington, USA
| | - Cody J Phillips
- Department of Surgery, Madigan Army Medical Center, Tacoma, Fort Lewis, Washington, USA
| | - Edward W Malin
- Department of Surgery, Madigan Army Medical Center, Tacoma, Fort Lewis, Washington, USA
| | - Vijay S Gorantla
- Department of Surgery, Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA
| | - Joseph W Harding
- Department of Integrative Physiology & Neuroscience, Washington State University, Pullman, WA, USA
| | - Shashikumar K Salgar
- Department of Clinical Investigation, Madigan Army Medical Center, Tacoma, Fort Lewis, Washington, USA
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Fontaine C, Yeager EA, Sledziona M, Jones AK, Cheetham J. Revitalizing the common peroneal function index for assessing functional recovery following nerve injury. Brain Behav 2021; 11:e01968. [PMID: 33314721 PMCID: PMC7882187 DOI: 10.1002/brb3.1968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 10/04/2020] [Accepted: 11/02/2020] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND AND AIMS Peripheral nerve injury is common with poor functional recovery and consequent high personal and societal costs. Sciatic nerve transection and assessment of recovery using sciatic functional index (SFI) are widely used. SFI is biologically limited as axonal misdirection of axons supplying flexors and extensors in the hindlimb, after nerve injury can lead to synkinetic innervation and function which does not correspond to the degree of axonal regeneration. METHODS We reevaluated the use of traditional metrics such as print length (PL), toe spread (TS), and intermediate toe spread (ITS) as well as hock angle at mid-swing as approaches for determining recovery. We used two alternative approaches in discrete cohorts of rats following common peroneal crush injury, transection with repair and critical gap, using transection with ligation as a negative control. We compared walking track analysis (print) with digital capture and kinematics. RESULTS PL, TS, and ITS varied as expected after injury. The traditional functional index for common peroneal injury using inked prints failed to describe recovery and we derived new indices to describe recovery (all R2 > 0.88, p < .0001) although pre-injury PFI was never attained by any of the models. Kinematic analysis identified hock angle at mid-swing as a useful predictor of recovery (p < .0001). INTERPRETATION Using complementary approaches.
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Affiliation(s)
- Calder Fontaine
- Department of Clinical Sciences, Cornell College of Veterinary Medicine, Cornell University, Ithaca, NY, USA
| | - Eric A Yeager
- Department of Clinical Sciences, Cornell College of Veterinary Medicine, Cornell University, Ithaca, NY, USA
| | - Michael Sledziona
- Department of Clinical Sciences, Cornell College of Veterinary Medicine, Cornell University, Ithaca, NY, USA
| | - Amanda K Jones
- Department of Clinical Sciences, Cornell College of Veterinary Medicine, Cornell University, Ithaca, NY, USA
| | - Jonathan Cheetham
- Department of Clinical Sciences, Cornell College of Veterinary Medicine, Cornell University, Ithaca, NY, USA
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Ghergherehchi CL, Shores JT, Alderete J, Weitzel EK, Bittner GD. Methylene blue enhances polyethylene glycol-fusion repair of completely severed rat sciatic nerves. Neural Regen Res 2021; 16:2056-2063. [PMID: 33642394 PMCID: PMC8343334 DOI: 10.4103/1673-5374.308099] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Complete transection of peripheral mixed nerves immediately produces loss of sensory perception, muscle contractions and voluntary behavior mediated by the severed distal axons. In contrast to natural regeneration (~1 mm/d) of proximal axons that may eventually reinnervate denervated targets, re-innervation is restored within minutes by PEG-fusion that consists of neurorrhaphy and a sequence of well specified hypo- and isotonic calcium-free or calcium-containing solutions, the anti-oxidant methylene blue (MB) and the membrane fusogen polyethylene glycol (PEG). In this study, we examined the relative efficacy of PEG-fusion with no MB (0%), 0.5% MB, or 1% MB on the recovery of voluntary behaviors by female Sprague-Dawley rats with a complete mid-thigh severance of their sciatic nerve bathed in extracellular fluid or calcium-containing isotonic saline. The recovery of voluntary behaviors is the most relevant measure of success of any technique to repair peripheral nerve injuries. We assessed recovery by the sciatic functional index, a commonly used measure of voluntary hindlimb behaviors following complete sciatic transections. We reported that both 1% MB and 0.5% MB in sterile distilled water in our PEG-fusion protocol with neurorrhaphy significantly increased the rate and extent of behavioral recovery compared to PEG plus neurorrhaphy alone. Furthermore, 0.5% MB was as effective as 1% MB in voluntary behavioral recovery as assessed by the sciatic functional index. Since sterile 1% MB is no longer clinically available, we therefore recommend that 0.5% MB be included in upcoming human clinical trials to evaluate the safety and efficacy of PEG-fusion. All animal procedures were approved by the University of Texas Institutional Animal Care and Use Committee (AUP-2019-00225) on September 9, 2020.
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Affiliation(s)
- Cameron L Ghergherehchi
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, USA
| | - Jaimie T Shores
- Department of Plastic and Reconstructive Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Joseph Alderete
- Department of Surgery, RESTOR Laboratory, San Antonio, TX, USA
| | - Erik K Weitzel
- Department of Surgery, RESTOR Laboratory, San Antonio, TX, USA
| | - George D Bittner
- Department of Neuroscience, University of Texas at Austin, Austin, TX, USA
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12
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Van Nest DS, Kahan DM, Ilyas AM. Polyethylene Glycol Fusion of Nerve Injuries: Review of the Technique and Clinical Applicability. J Hand Microsurg 2020; 13:49-54. [PMID: 33867761 PMCID: PMC8041495 DOI: 10.1055/s-0040-1718651] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Traumatic peripheral nerve injuries present a particular challenge to hand surgeons as mechanisms of nerve-healing pose serious limitations to achieving complete functional recovery. The loss of distal axonal segments through Wallerian degeneration results in the loss of neuromuscular junctions and irreversible muscle atrophy. Current methods of repair depend on the outgrowth of proximal nerve fibers following direct end-to-end repair or gap repair techniques. Investigational techniques in nerve repair using polyethylene glycol (PEG) nerve fusion have been shown to bypass Wallerian degeneration by immediately restoring nerve axonal continuity, thus resulting in a rapid and more complete functional recovery. The purpose of this article is to review the current literature surrounding this novel technique for traumatic nerve repair, paying particular attention to the underlying physiology of nerve healing and the current applications of PEG fusion in the laboratory and clinical setting. This article also serves to identify areas of future investigation to further establish validity and feasibility and encourage the translation of PEG fusion into clinical use.
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Affiliation(s)
- Duncan S Van Nest
- Rothman Institute, Thomas Jefferson University, Philadelphia, Pennsylvania, United States
| | - David M Kahan
- Rothman Institute, Thomas Jefferson University, Philadelphia, Pennsylvania, United States
| | - Asif M Ilyas
- Rothman Institute, Thomas Jefferson University, Philadelphia, Pennsylvania, United States
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13
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Smith TA, Ghergherehchi CL, Tucker HO, Bittner GD. Coding transcriptome analyses reveal altered functions underlying immunotolerance of PEG-fused rat sciatic nerve allografts. J Neuroinflammation 2020; 17:287. [PMID: 33008419 PMCID: PMC7532577 DOI: 10.1186/s12974-020-01953-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 09/16/2020] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Current methods to repair ablation-type peripheral nerve injuries (PNIs) using peripheral nerve allografts (PNAs) often result in poor functional recovery due to immunological rejection as well as to slow and inaccurate outgrowth of regenerating axonal sprouts. In contrast, ablation-type PNIs repaired by PNAs, using a multistep protocol in which one step employs the membrane fusogen polyethylene glycol (PEG), permanently restore sciatic-mediated behaviors within weeks. Axons and cells within PEG-fused PNAs remain viable, even though outbred host and donor tissues are neither immunosuppressed nor tissue matched. PEG-fused PNAs exhibit significantly reduced T cell and macrophage infiltration, expression of major histocompatibility complex I/II and consistently low apoptosis. In this study, we analyzed the coding transcriptome of PEG-fused PNAs to examine possible mechanisms underlying immunosuppression. METHODS Ablation-type sciatic PNIs in adult Sprague-Dawley rats were repaired using PNAs and a PEG-fusion protocol combined with neurorrhaphy. Electrophysiological and behavioral tests confirmed successful PEG-fusion of PNAs. RNA sequencing analyzed differential expression profiles of protein-coding genes between PEG-fused PNAs and negative control PNAs (not treated with PEG) at 14 days PO, along with unoperated control nerves. Sequencing results were validated by quantitative reverse transcription PCR (RT-qPCR), and in some cases, immunohistochemistry. RESULTS PEG-fused PNAs display significant downregulation of many gene transcripts associated with innate and adaptive allorejection responses. Schwann cell-associated transcripts are often upregulated, and cellular processes such as extracellular matrix remodeling and cell/tissue development are particularly enriched. Transcripts encoding several potentially immunosuppressive proteins (e.g., thrombospondins 1 and 2) also are upregulated in PEG-fused PNAs. CONCLUSIONS This study is the first to characterize the coding transcriptome of PEG-fused PNAs and to identify possible links between alterations of the extracellular matrix and suppression of the allorejection response. The results establish an initial molecular basis to understand mechanisms underlying PEG-mediated immunosuppression.
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Affiliation(s)
- Tyler A Smith
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA
| | | | - Haley O Tucker
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA
| | - George D Bittner
- Department of Neuroscience, University of Texas at Austin, Austin, TX, 78712, USA.
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14
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Smith TA, Ghergherehchi CL, Mikesh M, Shores JT, Tucker HO, Bittner GD. Polyethylene glycol-fusion repair of sciatic allografts in female rats achieves immunotolerance via attenuated innate and adaptive responses. J Neurosci Res 2020; 98:2468-2495. [PMID: 32931034 DOI: 10.1002/jnr.24720] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 07/31/2020] [Accepted: 08/11/2020] [Indexed: 12/17/2022]
Abstract
Ablation/segmental loss peripheral nerve injuries (PNIs) exhibit poor functional recovery due to slow and inaccurate outgrowth of regenerating axons. Viable peripheral nerve allografts (PNAs) as growth-guide conduits are immunologically rejected and all anucleated donor/host axonal segments undergo Wallerian degeneration. In contrast, we report that ablation-type sciatic PNIs repaired by neurorrhaphy of viable sciatic PNAs and a polyethylene glycol (PEG)-fusion protocol using PEG immediately restored axonal continuity for many axons, reinnervated/maintained their neuromuscular junctions, and prevented much Wallerian degeneration. PEG-fused PNAs permanently restored many sciatic-mediated behaviors within 2-6 weeks. PEG-fused PNAs were not rejected even though host/donors were neither immunosuppressed nor tissue-matched in outbred female Sprague Dawley rats. Innate and adaptive immune responses to PEG-fused sciatic PNAs were analyzed using electron microscopy, immunohistochemistry, and quantitative reverse transcription polymerase chain reaction for morphological features, T cell and macrophage infiltration, major histocompatibility complex (MHC) expression, apoptosis, expression of cytokines, chemokines, and cytotoxic effectors. PEG-fused PNAs exhibited attenuated innate and adaptive immune responses by 14-21 days postoperatively, as evidenced by (a) many axons and cells remaining viable, (b) significantly reduced infiltration of cytotoxic and total T cells and macrophages, (c) significantly reduced expression of inflammatory cytokines, chemokines, and MHC proteins, (d) consistently low apoptotic response. Morphologically and/or biochemically, PEG-fused sciatic PNAs often resembled sciatic autografts or intact sciatic nerves. In brief, PEG-fused PNAs are an unstudied, perhaps unique, example of immune tolerance of viable allograft tissue in a nonimmune-privileged environment and could greatly improve the clinical outcomes for PNIs relative to current protocols.
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Affiliation(s)
- Tyler A Smith
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | | | - Michelle Mikesh
- Department of Neuroscience, University of Texas at Austin, Austin, TX, USA
| | - Jaimie T Shores
- Department of Plastic and Reconstructive Surgery, Vascularized Composite Allotransplantation (VCA) Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Haley O Tucker
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | - George D Bittner
- Department of Neuroscience, University of Texas at Austin, Austin, TX, USA
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15
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Vest M, Guida A, Colombini C, Cordes K, Pena D, Maki M, Briones M, Antonio S, Hollifield C, Tian E, James L, Borashan C, Woodson J, Rovig J, Shihadeh H, Karabachev A, Brosious J, Pistorio A. Closing the Gap Between Mammalian and Invertebrate Peripheral Nerve Injury: Protocol for a Novel Nerve Repair. JMIR Res Protoc 2020; 9:e18706. [PMID: 32851981 PMCID: PMC7484768 DOI: 10.2196/18706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 06/22/2020] [Accepted: 06/23/2020] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Outcomes after peripheral nerve injuries are poor despite current nerve repair techniques. Currently, there is no conclusive evidence that mammalian axons are capable of spontaneous fusion after transection. Notably, certain invertebrate species are able to auto-fuse after transection. Although mammalian axonal auto-fusion has not been observed experimentally, no mammalian study to date has demonstrated regenerating axolemmal membranes contacting intact distal segment axolemmal membranes to determine whether mammalian peripheral nerve axons have the intrinsic mechanisms necessary to auto-fuse after transection. OBJECTIVE This study aims to assess fusion competence between regenerating axons and intact distal segment axons by enhancing axon regeneration, delaying Wallerian degeneration, limiting the immune response, and preventing myelin obstruction. METHODS This study will use a rat sciatic nerve model to evaluate the effects of a novel peripheral nerve repair protocol on behavioral, electrophysiologic, and morphologic parameters. This protocol consists of a variety of preoperative, intraoperative, and postoperative interventions. Fusion will be assessed with electrophysiological conduction of action potentials across the repaired transection site. Axon-axon contact will be assessed with transmission electron microscopy. Behavioral recovery will be analyzed with the sciatic functional index. A total of 36 rats will be used for this study. The experimental group will use 24 rats and the negative control group will use 12 rats. For both the experimental and negative control groups, there will be both a behavior group and another group that will undergo electrophysiological and morphological analysis. The primary end point will be the presence or absence of action potentials across the lesion site. Secondary end points will include behavioral recovery with the sciatic functional index and morphological analysis of axon-axon contact between regenerating axons and intact distal segment axons. RESULTS The author is in the process of grant funding and institutional review board approval as of March 2020. The final follow-up will be completed by December 2021. CONCLUSIONS In this study, the efficacy of the proposed novel peripheral nerve repair protocol will be evaluated using behavioral and electrophysiologic parameters. The author believes this study will provide information regarding whether spontaneous axon fusion is possible in mammals under the proper conditions. This information could potentially be translated to clinical trials if successful to improve outcomes after peripheral nerve injury. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID) PRR1-10.2196/18706.
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Affiliation(s)
- Maxwell Vest
- Department of Plastic and Reconstructive Surgery, University of Nevada Las Vegas, Las Vegas, NV, United States
| | - Addison Guida
- Department of Plastic and Reconstructive Surgery, University of Nevada Las Vegas, Las Vegas, NV, United States
| | - Cory Colombini
- Department of Plastic and Reconstructive Surgery, University of Nevada Las Vegas, Las Vegas, NV, United States
| | - Kristina Cordes
- Department of Plastic and Reconstructive Surgery, University of Nevada Las Vegas, Las Vegas, NV, United States
| | - Diana Pena
- Department of Plastic and Reconstructive Surgery, University of Nevada Las Vegas, Las Vegas, NV, United States
| | - Marwa Maki
- Department of Plastic and Reconstructive Surgery, University of Nevada Las Vegas, Las Vegas, NV, United States
| | - Michael Briones
- Department of Plastic and Reconstructive Surgery, University of Nevada Las Vegas, Las Vegas, NV, United States
| | - Sabrina Antonio
- Department of Plastic and Reconstructive Surgery, University of Nevada Las Vegas, Las Vegas, NV, United States
| | - Carmen Hollifield
- Department of Plastic and Reconstructive Surgery, University of Nevada Las Vegas, Las Vegas, NV, United States
| | - Elli Tian
- Department of Plastic and Reconstructive Surgery, University of Nevada Las Vegas, Las Vegas, NV, United States
| | - Lucas James
- Department of Plastic and Reconstructive Surgery, University of Nevada Las Vegas, Las Vegas, NV, United States
| | - Christian Borashan
- Department of Plastic and Reconstructive Surgery, University of Nevada Las Vegas, Las Vegas, NV, United States
| | - Johnnie Woodson
- Department of Plastic and Reconstructive Surgery, University of Nevada Las Vegas, Las Vegas, NV, United States
| | - John Rovig
- Department of Plastic and Reconstructive Surgery, University of Nevada Las Vegas, Las Vegas, NV, United States
| | - Hanaa Shihadeh
- Larner College of Medicine, University of Vermont, Burlington, VT, United States
| | - Alexander Karabachev
- Larner College of Medicine, University of Vermont, Burlington, VT, United States
| | - John Brosious
- Department of Plastic and Reconstructive Surgery, University of Nevada Las Vegas, Las Vegas, NV, United States
| | - Ashley Pistorio
- Department of Plastic and Reconstructive Surgery, University of Nevada Las Vegas, Las Vegas, NV, United States
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16
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Bu Y, Wang X, Li L, Hu X, Tan D, Li Z, Lai M, Qiu X, Sun F, Wang H, Yang F, Wu D, Guo J. Lithium Loaded Octa-Poly(Ethylene Glycol) Based Adhesive Facilitates Axon Regeneration and Reconnection of Transected Peripheral Nerves. Adv Healthc Mater 2020; 9:e2000268. [PMID: 32431051 DOI: 10.1002/adhm.202000268] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 04/30/2020] [Indexed: 12/14/2022]
Abstract
At present, reconnecting the transected nerve in clinic is still mainly reliant on surgery suture. This is a procedure that requires thorough training and is also time consuming. Here, an octa-poly(ethylene glycol) (PEG)-based adhesive for fast reconnecting of the transected peripheral nerve is reported. To enhance the therapeutic efficacy, a succinyl unit is applied to endow the controllably dissolvable property of the adhesive, and lithium is loaded in the adhesive to improve the axonal regeneration. Present data reveal that this adhesive possesses good cytocompatibility and can significantly shorten the reconnecting time of the transected nerve ends compared to that required for suture surgery. Histology, electrophysiological, and behavior assessments indicate that the adhesive reconnected nerves exhibit a low grade of fibrosis, inflammation response, and myoatrophy as well as robust axonal regeneration and functional recovery. Together, these results indicate that this octa-PEG adhesive can act as an alternative to traditional nerve suture in peripheral nerve injury.
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Affiliation(s)
- Yazhong Bu
- Beijing National Laboratory for Molecular SciencesInstitute of Chemistry Chinese Academy of Sciences Beijing 100190 China
- School of Chemical SciencesUniversity of Chinese Academy of Sciences Beijing 100049 China
| | - Xianghai Wang
- Department of Histology and EmbryologySouthern Medical University Guangzhou 510515 China
- Guangdong Provincial Key Laboratory of Construction and Detection in Tissue EngineeringSouthern Medical University Guangzhou 510515 China
- Guangzhou Regenerative Medicine and Health Guangdong Laboratory Guangzhou 510530 China
| | - Lixia Li
- Department of Histology and EmbryologySouthern Medical University Guangzhou 510515 China
- Guangdong Provincial Key Laboratory of Construction and Detection in Tissue EngineeringSouthern Medical University Guangzhou 510515 China
| | - Xiaofang Hu
- Department of Histology and EmbryologySouthern Medical University Guangzhou 510515 China
- Guangdong Provincial Key Laboratory of Construction and Detection in Tissue EngineeringSouthern Medical University Guangzhou 510515 China
| | - Dandan Tan
- Department of Histology and EmbryologySouthern Medical University Guangzhou 510515 China
- Guangdong Provincial Key Laboratory of Construction and Detection in Tissue EngineeringSouthern Medical University Guangzhou 510515 China
| | - Zhenlin Li
- Department of Histology and EmbryologySouthern Medical University Guangzhou 510515 China
- Guangdong Provincial Key Laboratory of Construction and Detection in Tissue EngineeringSouthern Medical University Guangzhou 510515 China
| | - Muhua Lai
- Department of Histology and EmbryologySouthern Medical University Guangzhou 510515 China
- Guangdong Provincial Key Laboratory of Construction and Detection in Tissue EngineeringSouthern Medical University Guangzhou 510515 China
| | - Xiaozhong Qiu
- Guangdong Provincial Key Laboratory of Construction and Detection in Tissue EngineeringSouthern Medical University Guangzhou 510515 China
| | - Feifei Sun
- Beijing National Laboratory for Molecular SciencesInstitute of Chemistry Chinese Academy of Sciences Beijing 100190 China
| | - Hufei Wang
- Beijing National Laboratory for Molecular SciencesInstitute of Chemistry Chinese Academy of Sciences Beijing 100190 China
- School of Chemical SciencesUniversity of Chinese Academy of Sciences Beijing 100049 China
| | - Fei Yang
- Beijing National Laboratory for Molecular SciencesInstitute of Chemistry Chinese Academy of Sciences Beijing 100190 China
- School of Chemical SciencesUniversity of Chinese Academy of Sciences Beijing 100049 China
| | - Decheng Wu
- Beijing National Laboratory for Molecular SciencesInstitute of Chemistry Chinese Academy of Sciences Beijing 100190 China
- School of Chemical SciencesUniversity of Chinese Academy of Sciences Beijing 100049 China
| | - Jiasong Guo
- Department of Histology and EmbryologySouthern Medical University Guangzhou 510515 China
- Guangdong Provincial Key Laboratory of Construction and Detection in Tissue EngineeringSouthern Medical University Guangzhou 510515 China
- Guangzhou Regenerative Medicine and Health Guangdong Laboratory Guangzhou 510530 China
- Key Laboratory of Mental Health of the Ministry of EducationGuangdong‐Hong Kong‐Macao Greater Bay Area Center for Brain Science and Brain‐Inspired IntelligenceGuangdong Province Key Laboratory of Psychiatric Disorders Guangzhou 510515 China
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17
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Brown BL, Sandelski MM, Drejet SM, Runge EM, Shipchandler TZ, Jones KJ, Walker CL. Facial nerve repair utilizing intraoperative repair strategies. Laryngoscope Investig Otolaryngol 2020; 5:552-559. [PMID: 32596500 PMCID: PMC7314485 DOI: 10.1002/lio2.411] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 04/27/2020] [Accepted: 05/18/2020] [Indexed: 12/25/2022] Open
Abstract
OBJECTIVES To determine whether functional and anatomical outcomes following suture neurorrhaphy are improved by the addition of electrical stimulation with or without the addition of polyethylene glycol (PEG). METHODS In a rat model of facial nerve injury, complete facial nerve transection and repair was performed via (a) suture neurorrhaphy alone, (b) neurorrhaphy with the addition of brief (30 minutes) intraoperative electrical stimulation, or (c) neurorrhaphy with the addition electrical stimulation and PEG. Functional recovery was assessed weekly for 16 weeks. At 16 weeks postoperatively, motoneuron survival, amount of regrowth, and specificity of regrowth were assessed by branch labeling and tissue analysis. RESULTS The addition of brief intraoperative electrical stimulation improved all functional outcomes compared to suturing alone. The addition of PEG to electrical stimulation impaired this benefit. Motoneuron survival, amount of regrowth, and specificity of regrowth were unaltered at 16 weeks postoperative in all treatment groups. CONCLUSION The addition of brief intraoperative electrical stimulation to neurorrhaphy in this rodent model shows promising neurological benefit in the surgical repair of facial nerve injury. LEVEL OF EVIDENCE Animal study.
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Affiliation(s)
- Brandon L. Brown
- Department of Anatomy, Cell Biology and PhysiologyIndiana University School of MedicineIndianapolisIndianaUSA
- Department of Anatomical Sciences and NeurobiologyUniversity of LouisvilleLouisvilleKentuckyUSA
| | - Morgan M. Sandelski
- Department of Anatomy, Cell Biology and PhysiologyIndiana University School of MedicineIndianapolisIndianaUSA
| | - Sarah M. Drejet
- Department of OtolaryngologyIndiana University School of MedicineIndianapolisIndianaUSA
| | - Elizabeth M. Runge
- Department of Anatomy, Cell Biology and PhysiologyIndiana University School of MedicineIndianapolisIndianaUSA
| | - Taha Z. Shipchandler
- Department of OtolaryngologyIndiana University School of MedicineIndianapolisIndianaUSA
| | - Kathryn J. Jones
- Department of Anatomy, Cell Biology and PhysiologyIndiana University School of MedicineIndianapolisIndianaUSA
- Research and Development ServiceRichard L Roudebush Veterans Affairs Medical CenterIndianapolisIndianaUSA
| | - Chandler L. Walker
- Department of Anatomy, Cell Biology and PhysiologyIndiana University School of MedicineIndianapolisIndianaUSA
- Research and Development ServiceRichard L Roudebush Veterans Affairs Medical CenterIndianapolisIndianaUSA
- Department of Biomedical Sciences and Comprehensive CareIndiana University School of DentistryIndianapolisIndianaUSA
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18
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Paskal AM, Paskal W, Pietruski P, Kusmierczyk Z, Jankowska-Steifer E, Andrychowski J, Wlodarski PK. Neuroregenerative effects of polyethylene glycol and FK-506 in a rat model of sciatic nerve injury. J Plast Reconstr Aesthet Surg 2019; 73:222-230. [PMID: 31759923 DOI: 10.1016/j.bjps.2019.10.011] [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: 12/29/2018] [Revised: 09/29/2019] [Accepted: 10/05/2019] [Indexed: 01/25/2023]
Abstract
The recently introduced polyethylene glycol (PEG) treatment restores axonal continuity after nerve injury, leading to rapid recovery of nerve function. The impact of PEG therapy on neuroregeneration has not yet been compared with any intervention with an established proneuroregenerative potential. FK-506 is an immunosuppressive agent with documented proneuroregenerative potential in nerve injury models. The aim of this study was to compare the effects of PEG therapy and preinjury FK-506 administration in rats with sciatic nerve transection injury. Four groups of male Sprague Dawley rats (seven per group) underwent sciatic nerve transection with primary repair. Group A received placebo injections, group B placebo injections and PEG treatment, group C FK-506 injections, and group D both FK-506 injections and PEG treatment. Clinical outcomes were assessed by the skin prick test and Sciatic Functional Index (SFI). Regenerated nerves underwent histomorphometric analysis. The histomorphometric analysis demonstrated that compared with the controls, nerve specimens from all treated groups showed signs of enhanced neuroregeneration (higher mean axonal area) (p < 0.001). The histomorphometric parameters for group D (PEG + FK-506), mean axonal area (p < 0.001) and axonal count (p > 0.05), were significantly better than those in the other study groups. The Form factor was closest to its optimal values in group B (p < 0.0001). At the end of the study, mean skin prick test scores in all treated groups were significantly higher than those in controls (p > 0.05). During the first postoperative week, PEG-treated rats (groups B and D) presented with higher values of the SFI than animals from groups A and C, but the difference was not statistically significant. Combined therapy with PEG and FK-506 seems to produce better neuroregeneration outcomes than a simple suture-based repair complemented with either PEG or FK-506 treatment.
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Affiliation(s)
- Adriana M Paskal
- Department of Methodology, Laboratory of Centre for Preclinical Research, Medical University of Warsaw, Banacha 1B, 02-097 Warsaw, Poland
| | - Wiktor Paskal
- Department of Methodology, Laboratory of Centre for Preclinical Research, Medical University of Warsaw, Banacha 1B, 02-097 Warsaw, Poland.
| | - Piotr Pietruski
- Timeless Plastic Surgery Clinic, gen. Romana Abrahama 18/322, 03-982 Warsaw, Poland
| | - Zofia Kusmierczyk
- Department of Experimental and Clinical Physiology, Laboratory of Centre for Preclinical Research, Medical University of Warsaw, Banacha 1B, 02-097 Warsaw, Poland
| | - Ewa Jankowska-Steifer
- Department of Histology and Embryology, Laboratory of Centre for Preclinical Research, Medical University of Warsaw, Banacha 1B, 02-097 Warsaw, Poland.
| | - Jaroslaw Andrychowski
- Department of Neurology and Neurosurgery, Faculty of Medical Sciences, University of Warmia and Mazury in Olsztyn, Warszawska 30, 10-082 Olsztyn, Poland.
| | - Pawel K Wlodarski
- Department of Methodology, Laboratory of Centre for Preclinical Research, Medical University of Warsaw, Banacha 1B, 02-097 Warsaw, Poland.
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19
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Salomone R. Response to Bittner et al.: Polyethylene glycol fusion associated with antioxidants: A new promise in the treatment of traumatic paralysis. Head Neck 2019; 41:3740-3742. [DOI: 10.1002/hed.25900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 07/22/2019] [Indexed: 11/10/2022] Open
Affiliation(s)
- Raquel Salomone
- Department of OtorhinolaryngologyUniversity of São Paulo Medical School São Paulo Brazil
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20
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Vargas SA, Bittner GD. Natural mechanisms and artificial PEG-induced mechanism that repair traumatic damage to the plasmalemma in eukaryotes. CURRENT TOPICS IN MEMBRANES 2019; 84:129-167. [PMID: 31610860 DOI: 10.1016/bs.ctm.2019.07.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Eukaryotic tissues are composed of individual cells surrounded by a plasmalemma that consists of a phospholipid bilayer with hydrophobic heads that bind cell water. Bound-water creates a thermodynamic barrier that impedes the fusion of a plasmalemma with other membrane-bound intracellular structures or with the plasmalemma of adjacent cells. Plasmalemmal damage consisting of small or large holes or complete transections of a cell or axon results in calcium influx at the lesion site. Calcium activates fusogenic pathways that have been phylogenetically conserved and that lower thermodynamic barriers for fusion of membrane-bound structures. Calcium influx also activates phylogenetically conserved sealing mechanisms that mobilize the gradual accumulation and fusion of vesicles/membrane-bound structures that seal the damaged membrane. These naturally occurring sealing mechanisms for different cells vary based on the type of lesion, the type of cell, the proximity of intracellular membranous structures to the lesion and the relation to adjacent cells. The reliability of different measures to assess plasmalemmal sealing need be carefully considered for each cell type. Polyethylene glycol (PEG) bypasses calcium and naturally occurring fusogenic pathways to artificially fuse adjacent cells (PEG-fusion) or artificially seal transected axons (PEG-sealing). PEG-fusion techniques can also be used to rapidly rejoin the closely apposed, open ends of severed axons. PEG-fused axons do not (Wallerian) degenerate and PEG-fused nerve allografts are not immune-rejected, and enable behavioral recoveries not observed for any other clinical treatment. A better understanding of natural and artificial mechanisms that induce membrane fusion should provide better clinical treatment for many disorders involving plasmalemmal damage.
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Affiliation(s)
- Sara A Vargas
- Department of Neuroscience, University of Texas at Austin, Austin, TX, United states
| | - George D Bittner
- Department of Neuroscience, University of Texas at Austin, Austin, TX, United states.
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21
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Bittner G, Ghergherehchi C, Mikesh M, Sengelaub D, Trevino R, Shores J. Salomone et al did not induce PEG‐fusion repair of severed rat facial nerves. Head Neck 2019; 41:3737-3739. [DOI: 10.1002/hed.25894] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 07/22/2019] [Indexed: 11/11/2022] Open
Affiliation(s)
- George Bittner
- Department of NeuroscienceUniversity of Texas at Austin Austin Texas
- Institute for Cellular and Molecular BiologyUniversity of Texas at Austin Austin Texas
| | - Cameron Ghergherehchi
- Department of NeuroscienceUniversity of Texas at Austin Austin Texas
- Institute for Cellular and Molecular BiologyUniversity of Texas at Austin Austin Texas
| | - Michelle Mikesh
- Department of NeuroscienceUniversity of Texas at Austin Austin Texas
| | - Dale Sengelaub
- Department of Psychological and Brain SciencesIndiana University Bloomington Indiana
| | - Richard Trevino
- Department of Orthopedic SurgeryWellspan Teaching Hospitals York Pennsylvania
| | - Jamie Shores
- Department of Plastic and Reconstructive SurgeryJohns Hopkins University School of Medicine Baltimore Maryland
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22
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Messineo E, Pollins A, Thayer W. Optimization and evaluation of an in vitro model of PEG-mediated fusion of nerve cell bodies. J Clin Neurosci 2019; 63:189-195. [DOI: 10.1016/j.jocn.2019.01.037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 01/20/2019] [Accepted: 01/28/2019] [Indexed: 01/27/2023]
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23
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Bingham JR, Kniery KR, Jorstad NL, Horkayne-Szakaly I, Hoffer ZS, Salgar SK. "Stem cell therapy to promote limb function recovery in peripheral nerve damage in a rat model" - Experimental research. Ann Med Surg (Lond) 2019; 41:20-28. [PMID: 31011420 PMCID: PMC6463551 DOI: 10.1016/j.amsu.2019.03.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 02/26/2019] [Accepted: 03/24/2019] [Indexed: 02/06/2023] Open
Abstract
Background Optimizing nerve regeneration and mitigating muscle atrophy are the keys to successful outcomes in peripheral nerve damage. We investigated whether mesenchymal stem cell (MSC) therapy can improve limb function recovery in peripheral nerve damage. Materials and methods We used sciatic nerve transection/repair (SNR) and individual nerve transection/repair (INR; branches of sciatic nerve - tibial, peroneal, sural) models to study the effect of MSCs on proximal and distal peripheral nerve damages, respectively, in male Lewis rats. Syngeneic MSCs (5 × 106; passage≤6) or saline were administered locally and intravenously. Sensory/motor functions (SF/MF) of the limb were assessed. Results Rat MSCs (>90%) were CD29+, CD90+, CD34−, CD31− and multipotent. Total SF at two weeks post-SNR & INR with or without MSC therapy was ∼1.2 on a 0–3 grading scale (0 = No function; 3 = Normal); by 12 weeks it was 2.6–2.8 in all groups (n ≥ 9/group). MSCs accelerated SF onset. At eight weeks post-INR, sciatic function index (SFI), a measure of MF (0 = Normal; −100 = Nonfunctional) was −34 and −77 in MSC and vehicle groups, respectively (n ≥ 9); post-SNR it was −72 and −92 in MSC and vehicle groups, respectively. Long-term MF (24 weeks) was apparent in MSC treated INR (SFI -63) but not in SNR (SFI -100). Gastrocnemius muscle atrophy was significantly reduced (P < 0.05) in INR. Nerve histomorphometry revealed reduced axonal area (P < 0.01) but no difference in myelination (P > 0.05) in MSC treated INR compared to the naive contralateral nerve. Conclusion MSC therapy in peripheral nerve damage appears to improve nerve regeneration, mitigate flexion-contractures, and promote limb functional recovery. Mesenchymal stem cell (MSC) therapy improved limb functional recovery. MSCs improved nerve regeneration and mitigated foot flexion-contractures. Limb muscle atrophy was significantly reduced in individual nerve repair (INR). Functional recovery in distal nerve repair (INR) was superior to proximal (SNR). MSC therapy is attractive, feasible & promising in peripheral nerve injury repair.
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Affiliation(s)
- Jason R Bingham
- Department of Surgery, Madigan Army Medical Center, Tacoma, WA, 98431, USA
| | - Kevin R Kniery
- Department of Surgery, Madigan Army Medical Center, Tacoma, WA, 98431, USA
| | - Nikolas L Jorstad
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Iren Horkayne-Szakaly
- Department of Neuropathology & Ophthalmic Pathology, Joint Pathology Center, Defense Health Agency, Silver Spring, MD, 20910, USA
| | - Zachary S Hoffer
- Department of Pathology, Madigan Army Medical Center, Tacoma, WA, 98431, USA
| | - Shashikumar K Salgar
- Department of Clinical Investigation, Madigan Army Medical Center, Tacoma, WA, 98431, USA
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Paskal AM, Paskal W, Pietruski P, Wlodarski PK. Polyethylene Glycol: The Future of Posttraumatic Nerve Repair? Systemic Review. Int J Mol Sci 2019; 20:E1478. [PMID: 30909624 PMCID: PMC6471459 DOI: 10.3390/ijms20061478] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 03/18/2019] [Accepted: 03/22/2019] [Indexed: 12/13/2022] Open
Abstract
Peripheral nerve injury is a common posttraumatic complication. The precise surgical repair of nerve lesion does not always guarantee satisfactory motor and sensory function recovery. Therefore, enhancement of the regeneration process is a subject of many research strategies. It is believed that polyethylene glycol (PEG) mediates axolemmal fusion, thus enabling the direct restoration of axon continuity. It also inhibits Wallerian degeneration and recovers nerve conduction. This systemic review, performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, describes and summarizes published studies on PEG treatment efficiency in various nerve injury types and repair techniques. Sixteen original experimental studies in animal models and one in humans were analyzed. PEG treatment superiority was reported in almost all experiments (based on favorable electrophysiological, histological, or behavioral results). To date, only one study attempted to transfer the procedure into the clinical phase. However, some technical aspects, e.g., the maximal delay between trauma and successful treatment, await determination. PEG therapy is a promising prospect that may improve the surgical treatment of peripheral nerve injuries in the clinical practice.
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Affiliation(s)
- Adriana M Paskal
- Laboratory of Centre for Preclinical Research, Department of Research Methodology, Medical University of Warsaw, Banacha 1B, 02-091 Warsaw, Poland.
| | - Wiktor Paskal
- Laboratory of Centre for Preclinical Research, Department of Research Methodology, Medical University of Warsaw, Banacha 1B, 02-091 Warsaw, Poland.
| | - Piotr Pietruski
- Timeless Plastic Surgery Clinic, gen. Romana Abrahama 18/322, 03-982 Warsaw, Poland.
| | - Pawel K Wlodarski
- Laboratory of Centre for Preclinical Research, Department of Research Methodology, Medical University of Warsaw, Banacha 1B, 02-091 Warsaw, Poland.
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Fusogens: Chemical Agents That Can Rapidly Restore Function After Nerve Injury. J Surg Res 2019; 233:36-40. [DOI: 10.1016/j.jss.2018.07.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Revised: 05/03/2018] [Accepted: 07/03/2018] [Indexed: 11/17/2022]
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Lin YF, Xie Z, Zhou J, Chen HH, Shao WW, Lin HD. Effect of exogenous spastin combined with polyethylene glycol on sciatic nerve injury. Neural Regen Res 2019; 14:1271-1279. [PMID: 30804259 PMCID: PMC6425831 DOI: 10.4103/1673-5374.251336] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Polyethylene glycol can connect the distal and proximal ends of an injured nerve at the cellular level through axonal fusion to avoid Wallerian degeneration of the injured distal nerve and promote peripheral nerve regeneration. However, this method can only prevent Wallerian degeneration in 10% of axons because the cytoskeleton is not repaired in a timely fashion. Reconstruction of the cytoskeletal trunk and microtubule network has been suggested to be the key for improving the efficiency of axonal fusion. As a microtubule-severing protein, spastin has been used to enhance cytoskeletal reconstruction. Therefore, we hypothesized that spastin combined with polyethylene glycol can more effectively promote peripheral nerve regeneration. A total of 120 male Sprague-Dawley rats were randomly divided into sham, suture, polyethylene glycol, and polyethylene glycol + spastin groups. In suture group rats, only traditional nerve anastomosis of the end-to-end suture was performed after transection of the sciatic nerve. In polyethylene glycol and polyethylene glycol + spastin groups, 50 μL of polyethylene glycol or 25 μL of polyethylene glycol + 25 μL of spastin, respectively, were injected immediately under the epineurium of the distal suture. Sensory fiber regeneration distance, which was used to assess early nerve regeneration at 1 week after surgery, was shortest in the suture group, followed by polyethylene glycol group and greatest in the polyethylene glycol + spastin group. Behavioral assessment of motor function recovery in rats showed that limb function was restored in polyethylene glycol and polyethylene glycol + spastin groups at 8 weeks after surgery. At 1, 2, 4 and 8 weeks after surgery, sciatic functional index values and percentages of gastrocnemius muscle wet weight were highest in the sham group, followed by polyethylene glycol + spastin and polyethylene glycol groups, and lowest in the suture group. Masson staining was utilized to assess the morphology of muscle tissue. Morphological changes in skeletal muscle were detectable in suture, polyethylene glycol, and polyethylene glycol + spastin groups at 1, 2, 4, and 8 weeks after surgery. Among them, muscular atrophy of the suture group was most serious, followed by polyethylene glycol and polyethylene glycol + spastin groups. Ultrastructure of distal sciatic nerve tissue, as detected by transmission electron microscopy, showed a pattern of initial destruction, subsequent disintegration, and gradual repair in suture, polyethylene glycol, and polyethylene glycol + spastin groups at 1, 2, 4, and 8 weeks after surgery. As time proceeded, axonal ultrastructure gradually recovered. Indeed, the polyethylene glycol + spastin group was similar to the sham group at 8 weeks after surgery. Our findings indicate that the combination of polyethylene glycol and spastin can promote peripheral nerve regeneration. Moreover, the effect of this combination was better than that of polyethylene glycol alone, and both were superior to the traditional neurorrhaphy. This study was approved by the Animal Ethics Committee of the Second Military Medical University, China (approval No. CZ20170216) on March 16, 2017.
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Affiliation(s)
- Yao-Fa Lin
- Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, China
| | - Zheng Xie
- Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, China
| | - Jun Zhou
- Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai; Department of Orthopedics, The Second People's Hospital of Karamay, Karamay, Xinjiang Uygur Autonomous Region, China
| | - Hui-Hao Chen
- Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, China
| | - Wan-Wan Shao
- Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, China
| | - Hao-Dong Lin
- Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, China
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Salomone R, Jácomo AL, Bento RF, do Nascimento SB, Lezirovitz K, Hojaij FC, Costa HJZR. Polyethylene Glycol fusion associated with anti-oxidants: A new promise in the treatment of traumatic paralysis. Head Neck 2018; 40:2759. [PMID: 30593717 DOI: 10.1002/hed.25626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Raquel Salomone
- Department of Otorhinolaryngology, University of São Paulo Medical School, São Paulo, Brazil
| | - Alfredo Luiz Jácomo
- Department of Surgery, Anatomy Discipline, University of São Paulo Medical School, São Paulo, Brazil
| | - Ricardo F Bento
- Department of Otorhinolaryngology, University of São Paulo Medical School, São Paulo, Brazil
| | | | - Karina Lezirovitz
- Department of Genetics and Evolutionary Biology, Biosciences Institute, University of São Paulo, São Paulo, Brazil
| | - Flávio Carneiro Hojaij
- Department of Surgery, Anatomy Discipline, University of São Paulo Medical School, São Paulo, Brazil
| | - Heloisa J Z R Costa
- Department of Otorhinolaryngology, University of São Paulo Medical School, São Paulo, Brazil
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Ghergherehchi CL, Mikesh M, Sengelaub DR, Jackson DM, Smith T, Nguyen J, Shores JT, Bittner GD. Polyethylene glycol (PEG) and other bioactive solutions with neurorrhaphy for rapid and dramatic repair of peripheral nerve lesions by PEG-fusion. J Neurosci Methods 2018; 314:1-12. [PMID: 30586569 DOI: 10.1016/j.jneumeth.2018.12.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 12/17/2018] [Accepted: 12/19/2018] [Indexed: 12/30/2022]
Abstract
BACKGROUND Nervous system injuries in mammals often involve transection or segmental loss of peripheral nerves. Such injuries result in functional (behavioral) deficits poorly restored by naturally occurring 1-2 mm/d axonal outgrowths aided by primary repair or reconstruction. "Neurorrhaphy" or nerve repair joins severed connective tissues, but not severed cytoplasmic/plasmalemmal extensions (axons) within the tissue. NEW METHOD PEG-fusion consists of neurorrhaphy combined with a well-defined sequence of four pharmaceutical agents in solution, one containing polyethylene glycol (PEG), applied directly to closely apposed viable ends of severed axons. RESULTS PEG-fusion of rat sciatic nerves: (1) restores axonal continuity across coaptation site(s) within minutes, (2) prevents Wallerian degeneration of many distal severed axons, (3) preserves neuromuscular junctions, (4) prevents target muscle atrophy, (5) produces rapid and improved recovery of voluntary behaviors compared with neurorrhaphy alone, and (6) PEG-fused allografts are not rejected, despite no tissue-matching nor immunosuppression. COMPARISON WITH EXISTING METHODS If PEG-fusion protocols are not correctly executed, the results are similar to that of neurorrhaphy alone: (1) axonal continuity across coaptation site(s) is not re-established, (2) Wallerian degeneration of all distal severed axons rapidly occurs, (3) neuromuscular junctions are non-functional, (4) target muscle atrophy begins within weeks, (5) recovery of voluntary behavior occurs, if ever, after months to levels well-below that observed in unoperated animals, and (6) allografts are either rejected or not well-accepted. CONCLUSION PEG-fusion produces rapid and dramatic recovery of function following rat peripheral nerve injuries.
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Affiliation(s)
| | - Michelle Mikesh
- Department of Neuroscience, University of Texas at Austin, Austin, TX, 78712, USA.
| | - Dale R Sengelaub
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, 47405, USA.
| | | | - Tyler Smith
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA.
| | - Jacklyn Nguyen
- Department of Neuroscience, University of Texas at Austin, Austin, TX, 78712, USA.
| | - Jaimie T Shores
- Department of Plastic and Reconstructive Surgery, Vascularized Composite Allotransplantation (VCA) Laboratory, Johns Hopkins University School of Medicine, Ross Research Building 749D, 720 Rutland Avenue, Baltimore, MD, 21205, USA.
| | - George D Bittner
- Department of Neuroscience, University of Texas at Austin, Austin, TX, 78712, USA.
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Aghaie T, Jazayeri MH, Manian M, Khani L, Erfani M, Rezayi M, Ferns GA, Avan A. Gold nanoparticle and polyethylene glycol in neural regeneration in the treatment of neurodegenerative diseases. J Cell Biochem 2018; 120:2749-2755. [DOI: 10.1002/jcb.27415] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 07/12/2018] [Indexed: 12/15/2022]
Affiliation(s)
- Tayebe Aghaie
- Department of Immunology School of Medicine, Iran University of Medical Sciences Tehran Iran
| | - Mir Hadi Jazayeri
- Department of Immunology School of Medicine, Iran University of Medical Sciences Tehran Iran
- Immunology Research Center, Iran University of Medical Sciences Tehran Iran
| | - Mostafa Manian
- Department of Immunology School of Medicine, Iran University of Medical Sciences Tehran Iran
| | - leila Khani
- Department of Immunology School of Medicine, Iran University of Medical Sciences Tehran Iran
| | - Marjan Erfani
- Department of Neurology Ghaem Hospital, Mashhad University of Medical Sciences Mashhad Iran
| | - Majid Rezayi
- Metabolic syndrome Research center, Mashhad University of Medical Sciences Mashhad Iran
| | - Gordon A. Ferns
- Brighton & Sussex Medical School, Division of Medical Education, Falmer Brighton UK
| | - Amir Avan
- Metabolic syndrome Research center, Mashhad University of Medical Sciences Mashhad Iran
- Department of Modern Sciences and Technologies School of Medicine, Mashhad University of Medical Sciences Mashhad Iran
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Neumann B, Linton C, Giordano-Santini R, Hilliard MA. Axonal fusion: An alternative and efficient mechanism of nerve repair. Prog Neurobiol 2018; 173:88-101. [PMID: 30500382 DOI: 10.1016/j.pneurobio.2018.11.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 11/22/2018] [Accepted: 11/26/2018] [Indexed: 02/07/2023]
Abstract
Injuries to the nervous system can cause lifelong morbidity due to the disconnect that occurs between nerve cells and their cellular targets. Re-establishing these lost connections is the ultimate goal of endogenous regenerative mechanisms, as well as those induced by exogenous manipulations in a laboratory or clinical setting. Reconnection between severed neuronal fibers occurs spontaneously in some invertebrate species and can be induced in mammalian systems. This process, known as axonal fusion, represents a highly efficient means of repair after injury. Recent progress has greatly enhanced our understanding of the molecular control of axonal fusion, demonstrating that the machinery required for the engulfment of apoptotic cells is repurposed to mediate the reconnection between severed axon fragments, which are subsequently merged by fusogen proteins. Here, we review our current understanding of naturally occurring axonal fusion events, as well as those being ectopically produced with the aim of achieving better clinical outcomes.
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Affiliation(s)
- Brent Neumann
- Neuroscience Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne VIC 3800, Australia.
| | - Casey Linton
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Rosina Giordano-Santini
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Massimo A Hilliard
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
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Abstract
Background The management of peripheral nerve injuries remains a large challenge for plastic surgeons. With the inability to fuse axonal endings, results after microsurgical nerve repair have been inconsistent. Our current nerve repair strategies rely upon the slow and lengthy process of axonal regeneration (~1 mm/d). Polyethylene glycol (PEG) has been investigated as a potential axonal fusion agent; however, the percentage of axonal fusion has been inconsistent. The purpose of this study was to identify a PEG delivery device to standardize outcomes after attempted axonal fusion with PEG. Materials and Methods We used a rat sciatic nerve injury model in which we completely transected and repaired the left sciatic nerve to evaluate the efficacy of PEG fusion over a span of 12 weeks. In addition, we evaluated the effectiveness of a delivery device's ability to optimize results after PEG fusion. Results We found that PEG rapidly (within minutes) restores axonal continuity as assessed by electrophysiology, fluorescent retrograde tracer, and diffusion tensor imaging. Immunohistochemical analysis shows that motor axon counts are significantly increased at 1 week, 4 weeks, and 12 weeks postoperatively in PEG-treated animals. Furthermore, PEG restored behavioral functions up to 50% compared with animals that received the criterion standard epineurial repair (control animals). Conclusions The ability of PEG to rapidly restore nerve function after neurotmesis could have vast implications on the clinical management of traumatic injuries to peripheral nerves.
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Yi S, Xu L, Gu X. Scaffolds for peripheral nerve repair and reconstruction. Exp Neurol 2018; 319:112761. [PMID: 29772248 DOI: 10.1016/j.expneurol.2018.05.016] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 05/05/2018] [Accepted: 05/13/2018] [Indexed: 12/22/2022]
Abstract
Trauma-associated peripheral nerve defect is a widespread clinical problem. Autologous nerve grafting, the current gold standard technique for the treatment of peripheral nerve injury, has many internal disadvantages. Emerging studies showed that tissue engineered nerve graft is an effective substitute to autologous nerves. Tissue engineered nerve graft is generally composed of neural scaffolds and incorporating cells and molecules. A variety of biomaterials have been used to construct neural scaffolds, the main component of tissue engineered nerve graft. Synthetic polymers (e.g. silicone, polyglycolic acid, and poly(lactic-co-glycolic acid)) and natural materials (e.g. chitosan, silk fibroin, and extracellular matrix components) are commonly used along or together to build neural scaffolds. Many other materials, including the extracellular matrix, glass fabrics, ceramics, and metallic materials, have also been used to construct neural scaffolds. These biomaterials are fabricated to create specific structures and surface features. Seeding supporting cells and/or incorporating neurotrophic factors to neural scaffolds further improve restoration effects. Preliminary studies demonstrate that clinical applications of these neural scaffolds achieve satisfactory functional recovery. Therefore, tissue engineered nerve graft provides a good alternative to autologous nerve graft and represents a promising frontier in neural tissue engineering.
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Affiliation(s)
- Sheng Yi
- Key laboratory of neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Lai Xu
- Key laboratory of neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Xiaosong Gu
- Key laboratory of neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China.
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Mikesh M, Ghergherehchi CL, Hastings RL, Ali A, Rahesh S, Jagannath K, Sengelaub DR, Trevino RC, Jackson DM, Bittner GD. Polyethylene glycol solutions rapidly restore and maintain axonal continuity, neuromuscular structures, and behaviors lost after sciatic nerve transections in female rats. J Neurosci Res 2018; 96:1223-1242. [PMID: 29659058 DOI: 10.1002/jnr.24225] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 01/30/2018] [Accepted: 01/31/2018] [Indexed: 12/15/2022]
Abstract
Complete severance of major peripheral mixed sensory-motor nerve proximally in a mammalian limb produces immediate loss of action potential conduction and voluntary behaviors mediated by the severed distal axonal segments. These severed distal segments undergo Wallerian degeneration within days. Denervated muscles atrophy within weeks. Slowly regenerating (∼1 mm/day) outgrowths from surviving proximal stumps that often nonspecifically reinnervate denervated targets produce poor, if any, restoration of lost voluntary behaviors. In contrast, in this study using completely transected female rat sciatic axons as a model system, we provide extensive morphometric, immunohistochemical, electrophysiological, and behavioral data to show that these adverse outcomes are avoided by microsuturing closely apposed axonal cut ends (neurorrhaphy) and applying a sequence of well-specified solutions, one of which contains polyethylene glycol (PEG). This "PEG-fusion" procedure within minutes reestablishes axoplasmic and axolemmal continuity and signaling by nonspecifically fusing (connecting) closely apposed open ends of severed motor and/or sensory axons at the lesion site. These PEG-fused axons continue to conduct action potentials and generate muscle action potentials and muscle twitches for months and do not undergo Wallerian degeneration. Continuously innervated muscle fibers undergo much less atrophy compared with denervated muscle fibers. Dramatic behavioral recovery to near-unoperated levels occurs within days to weeks, almost certainly by activating many central nervous system and peripheral nervous system synaptic and other plasticities, some perhaps to a greater extent than most neuroscientists would expect. Negative control transections in which neurorrhaphy and all solutions except the PEG-containing solution are applied produce none of these remarkably fortuitous outcomes observed for PEG-fusion.
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Affiliation(s)
- Michelle Mikesh
- Department of Neuroscience, University of Texas at Austin, Austin, Texas
| | | | | | - Amir Ali
- Department of Neuroscience, University of Texas at Austin, Austin, Texas
| | - Sina Rahesh
- Department of Neuroscience, University of Texas at Austin, Austin, Texas
| | - Karthik Jagannath
- Department of Neuroscience, University of Texas at Austin, Austin, Texas
| | - Dale R Sengelaub
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana
| | - Richard C Trevino
- Department of Orthopedic Surgery, Wellspan Teaching Hospitals, York, Pennsylvania
| | | | - George D Bittner
- Department of Neuroscience, University of Texas at Austin, Austin, Texas
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Mikesh M, Ghergherehchi CL, Rahesh S, Jagannath K, Ali A, Sengelaub DR, Trevino RC, Jackson DM, Tucker HO, Bittner GD. Polyethylene glycol treated allografts not tissue matched nor immunosuppressed rapidly repair sciatic nerve gaps, maintain neuromuscular functions, and restore voluntary behaviors in female rats. J Neurosci Res 2018; 96:1243-1264. [PMID: 29659046 DOI: 10.1002/jnr.24227] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 01/30/2018] [Accepted: 01/31/2018] [Indexed: 02/05/2023]
Abstract
Many publications report that ablations of segments of peripheral nerves produce the following unfortunate results: (1) Immediate loss of sensory signaling and motor control; (2) rapid Wallerian degeneration of severed distal axons within days; (3) muscle atrophy within weeks; (4) poor behavioral (functional) recovery after many months, if ever, by slowly-regenerating (∼1mm/d) axon outgrowths from surviving proximal nerve stumps; and (5) Nerve allografts to repair gap injuries are rejected, often even if tissue matched and immunosuppressed. In contrast, using a female rat sciatic nerve model system, we report that neurorrhaphy of allografts plus a well-specified-sequence of solutions (one containing polyethylene glycol: PEG) successfully addresses each of these problems by: (a) Reestablishing axonal continuity/signaling within minutes by nonspecific ally PEG-fusing (connecting) severed motor and sensory axons across each anastomosis; (b) preventing Wallerian degeneration by maintaining many distal segments of inappropriately-reconnected, PEG-fused axons that continuously activate nerve-muscle junctions; (c) maintaining innervation of muscle fibers that undergo much less atrophy than otherwise-denervated muscle fibers; (d) inducing remarkable behavioral recovery to near-unoperated levels within days to weeks, almost certainly by CNS and PNS plasticities well-beyond what most neuroscientists currently imagine; and (e) preventing rejection of PEG-fused donor nerve allografts with no tissue matching or immunosuppression. Similar behavioral results are produced by PEG-fused autografts. All results for Negative Control allografts agree with current neuroscience data 1-5 given above. Hence, PEG-fusion of allografts for repair of ablated peripheral nerve segments expand on previous observations in single-cut injuries, provoke reconsideration of some current neuroscience dogma, and further extend the potential of PEG-fusion in clinical practice.
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Affiliation(s)
- Michelle Mikesh
- Department of Neuroscience, University of Texas at Austin, Austin, Texas, 78712, USA
| | - Cameron L Ghergherehchi
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, 78712, USA
| | - Sina Rahesh
- Department of Neuroscience, University of Texas at Austin, Austin, Texas, 78712, USA
| | - Karthik Jagannath
- Department of Neuroscience, University of Texas at Austin, Austin, Texas, 78712, USA
| | - Amir Ali
- Department of Neuroscience, University of Texas at Austin, Austin, Texas, 78712, USA
| | - Dale R Sengelaub
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana, 47405, USA
| | - Richard C Trevino
- Department of Orthopedic Surgery, Wellspan Teaching Hospitals, York, PA, USA
| | | | - Haley O Tucker
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, 78712, USA
| | - George D Bittner
- Department of Neuroscience, University of Texas at Austin, Austin, Texas, 78712, USA
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35
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Salomone R, Jácomo AL, Nascimento SBD, Lezirovitz K, Hojaij FC, Costa HJZR, Bento RF. Polyethylene glycol fusion associated with antioxidants: A new promise in the treatment of traumatic facial paralysis. Head Neck 2018. [PMID: 29522265 DOI: 10.1002/hed.25122] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Recent studies in invertebrates have taught us that early cell membrane regeneration is determinant for axonal recovery and survival after trauma. Many authors obtained extraordinary results in neural regeneration using polyethylene glycol fusion protocols, which also involved microsutures and antioxidants. METHODS Sixty rats were evaluated with functional and histological protocol after facial nerve neurotmesis. Groups A and B had their stumps coapted with microsuture after 24 hours of neurotmesis and groups C and D after 72 hours. In addition to the microstructure, groups B and D used the polyethylene glycol-fusion protocol for the modulation of the Ca+2 . RESULTS At the sixth week, the latency of group D and duration of group B was lower than groups A and C (P = .011). The axonal diameter of the groups that used polyethylene glycol-fusion was higher than those who did not use polyethylene glycol-fusion (P ≤ .001). CONCLUSION Although not providing a functional improvement, polyethylene glycol-fusion slowed down demyelination.
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Affiliation(s)
- Raquel Salomone
- Department of Otorhinolaryngology, University of São Paulo Medical School, São Paulo, Brazil
| | - Alfredo Luiz Jácomo
- Department of Surgery, Discipline of Human Structural Topography, University of São Paulo Medical School, São Paulo, Brazil
| | | | - Karina Lezirovitz
- Department of Otorhinolaryngology, University of São Paulo Medical School, São Paulo, Brazil
| | - Flávio Carneiro Hojaij
- Department of Surgery, Discipline of Human Structural Topography, University of São Paulo Medical School, São Paulo, Brazil
| | | | - Ricardo Ferreira Bento
- Department of Otorhinolaryngology, University of São Paulo Medical School, São Paulo, Brazil
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Bamba R, Riley DC, Kim JS, Cardwell NL, Pollins AC, Shack RB, Thayer WP. Evaluation of a Nerve Fusion Technique With Polyethylene Glycol in a Delayed Setting After Nerve Injury. J Hand Surg Am 2018; 43:82.e1-82.e7. [PMID: 28823535 DOI: 10.1016/j.jhsa.2017.07.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 07/12/2017] [Accepted: 07/13/2017] [Indexed: 02/02/2023]
Abstract
PURPOSE Polyethylene glycol (PEG) has been hypothesized to restore axonal continuity using an in vivo rat sciatic nerve injury model when nerve repair occurs within minutes after nerve injury. We hypothesized that PEG could restore axonal continuity when nerve repair was delayed. METHODS The left sciatic nerves of female Sprague-Dawley rats were transected and repaired in an end-to-end fashion using standard microsurgical techniques at 3 time points (1, 8, and 24 hours) after injury. Polyethylene glycol was delivered to the neurorrhaphy in the experimental group. Post-repair compound action potentials were immediately recorded after repair. Animals underwent behavioral assessments at 3 days and 1 week after surgery using the sciatic functional index test. The animals were sacrificed at 1 week to obtain axon counts. RESULTS The PEG-treated nerves had improved compound action potential conduction and animals treated with PEG had improved sciatic function index. Compound action potential conduction was restored in PEG-fused rats when nerves were repaired at 1, 8, and 24 hours. In the control groups, no compound action potential conduction was restored when nerves were repaired. Sciatic functional index was superior in PEG-fused rats at 3 and 7 days after surgery compared with control groups at all 3 time points of nerve repair. Distal motor and sensory axon counts were higher in the PEG-treated rats. CONCLUSIONS Polyethylene glycol fusion is a new adjunct for nerve repair that allows rapid restoration of axonal continuity. It effective when delayed nerve repair is performed. CLINICAL RELEVANCE Nerve repair with application of PEG is a potential therapy that may have efficacy in a clinical setting. It is an experimental therapy that needs more investigation as well as clinical trials.
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Affiliation(s)
- Ravinder Bamba
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN; Department of Surgery, Georgetown University, Washington, DC.
| | - David Colton Riley
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN; Georgetown University School of Medicine, Washington, DC
| | - Justine S Kim
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN
| | - Nancy L Cardwell
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN
| | - Alonda C Pollins
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN
| | - R Bruce Shack
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN
| | - Wesley P Thayer
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN
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Bittner GD, Sengelaub DR, Ghergherehchi CL. Conundrums and confusions regarding how polyethylene glycol-fusion produces excellent behavioral recovery after peripheral nerve injuries. Neural Regen Res 2018; 13:53-57. [PMID: 29451204 PMCID: PMC5840989 DOI: 10.4103/1673-5374.224363] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Current Neuroscience dogma holds that transections or ablations of a segment of peripheral nerves produce: (1) Immediate loss of axonal continuity, sensory signaling, and motor control; (2) Wallerian rapid (1–3 days) degeneration of severed distal axons, muscle atrophy, and poor behavioral recovery after many months (if ever, after ablations) by slowly-regenerating (1 mm/d), proximal-stump outgrowths that must specifically reinnervate denervated targets; (3) Poor acceptance of microsutured nerve allografts, even if tissue-matched and immune-suppressed. Repair of transections/ablations by neurorrhaphy and well-specified-sequences of PEG-fusion solutions (one containing polyethylene glycol, PEG) successfully address these problems. However, conundrums and confusions regarding unorthodox and dramatic results of PEG-fusion repair in animal model systems often lead to misunderstandings. For example, (1) Axonal continuity and signaling is re-established within minutes by non-specifically PEG-fusing (connecting) severed motor and sensory axons across each lesion site, but remarkable behavioral recovery to near-unoperated levels takes several weeks; (2) Many distal stumps of inappropriately-reconnected, PEG-fused axons do not ever (Wallerian) degenerate and continuously innervate muscle fibers that undergo much less atrophy than otherwise-denervated muscle fibers; (3) Host rats do not reject PEG-fused donor nerve allografts in a non-immuno-privileged environment with no tissue matching or immunosuppression; (4) PEG fuses apposed open axonal ends or seals each shut (thereby preventing PEG-fusion), depending on the experimental protocol; (5) PEG-fusion protocols produce similar results in animal model systems and early human case studies. Hence, iconoclastic PEG-fusion data appropriately understood might provoke a re-thinking of some Neuroscience dogma and a paradigm shift in clinical treatment of peripheral nerve injuries.
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Affiliation(s)
- George D Bittner
- Department of Neuroscience, University of Texas at Austin, Austin, TX, USA
| | - Dale R Sengelaub
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA
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Kuo CC, Su HL, Chang TL, Chiang CY, Sheu ML, Cheng FC, Chen CJ, Sheehan J, Pan HC. Prevention of Axonal Degeneration by Perineurium Injection of Mitochondria in a Sciatic Nerve Crush Injury Model. Neurosurgery 2017; 80:475-488. [PMID: 28362972 DOI: 10.1093/neuros/nyw090] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 11/23/2016] [Indexed: 11/14/2022] Open
Abstract
Background Axon degeneration leads to cytoskeletal disassembly, metabolism imbalance, and mitochondrial dysfunction during neurodegeneration or nerve injury. Objective In this study, we assess the possibility of mitigating axon degeneration by local injection of mitochondria in a crushed sciatic nerve. Methods Sciatic nerve explants cocultured with mitochondria were assessed for the optimal dosage in local injection and nerve regeneration potential. The left sciatic nerve was crushed in Sprague-Dawley rats and then local injection of mitochondria into the distal end of the injured nerve was conducted for further assessment. Results Mitochondrial coculture attenuated cytoskeletal loss and oxidative stress in isolated nerve explants. In Vivo analyses also showed that mitochondrial transplantation improved animal neurobehaviors, electrophysiology of nerve conduction, and muscle activities. Mitochondria injection significantly attenuated the oxidative stress and increased the expression of neurotrophic factors both in injured nerves and denervated muscles, as well as restored muscular integrity, and increased the pool of muscular progenitor cells and total muscle weight. Conclusion Mitochondria injection can protect injured nerves from axonal degeneration both in Vitro and in Vivo. This improvement was accompanied with the expression of neurotrophic factors as well as the reduction of oxidative stress, which may account for the functional recovery of both injured nerves and denervated muscles.
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Affiliation(s)
- Chi-Chung Kuo
- Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan, China.,Department of Neurology, Taichung Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Taichung, Taiwan, China.,School of Medicine, Tzu Chi University, Hualien, Taiwan, China
| | - Hong-Lin Su
- Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan, China
| | - Tzu-Lin Chang
- Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan, China
| | - Chien-Yi Chiang
- Institute of Biomedical Sciences, Agriculture Biotechnology Center, National Chung-Hsing University, Taichung, Taiwan, China
| | - Meei-Ling Sheu
- Institute of Biomedical Sciences, Agriculture Biotechnology Center, National Chung-Hsing University, Taichung, Taiwan, China
| | - Fu-Chou Cheng
- Department of Medical Research, Taichung Veterans General Hospital, Taichung, Taiwan, China
| | - Chun-Jung Chen
- Department of Medical Research, Taichung Veterans General Hospital, Taichung, Taiwan, China
| | - Jason Sheehan
- Department of Neurosurgery, University of Virginia, Charlottesville, Virginia, USA
| | - Hung-Chuan Pan
- Department of Neurosurgery, Taichung Veterans General Hospital, Taichung, Taiwan, China.,Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan, China
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Suchyta MA, Sabbagh MD, Morsy M, Mardini S, Moran SL. Advances in peripheral nerve regeneration as it relates to VCA. ACTA ACUST UNITED AC 2017. [DOI: 10.1080/23723505.2017.1344347] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
| | - M. Diya Sabbagh
- Department of Plastic Surgery, Mayo Clinic, Rochester, MN, USA
| | - Mohamed Morsy
- Department of Plastic Surgery, Mayo Clinic, Rochester, MN, USA
- Department of Orthopedic Surgery, Assiut University Hospital, Assiut University, Assiut, Egypt
| | - Samir Mardini
- Department of Plastic Surgery, Mayo Clinic, Rochester, MN, USA
| | - Steven L. Moran
- Department of Plastic Surgery, Mayo Clinic, Rochester, MN, USA
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Poellmann MJ, Lee RC. Repair and Regeneration of the Wounded Cell Membrane. REGENERATIVE ENGINEERING AND TRANSLATIONAL MEDICINE 2017. [DOI: 10.1007/s40883-017-0031-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Abstract
BACKGROUND Peripheral nerve injury can have a devastating impact on our military and veteran population. Current strategies for peripheral nerve repair include techniques such as nerve tubes, nerve grafts, tissue matrices, and nerve growth guides to enhance the number of regenerating axons. Even with such advanced techniques, it takes months to regain function. In animal models, polyethylene glycol (PEG) therapy has shown to improve both physiologic and behavioral outcomes after nerve transection by fusion of a portion of the proximal axons to the distal axon stumps. The objective of this study was to show the efficacy of PEG fusion in humans and to retrospectively compare PEG fusion to standard nerve repair. METHODS Patients with traumatic lacerations involving digital nerves were treated with PEG after standard microsurgical neurorrhaphy. Sensory assessment after injury was performed at 1 week, 2 weeks, 1 month, and 2 months using static two-point discrimination and Semmes-Weinstein monofilament testing. The Medical Research Council Classification (MRCC) for Sensory Recovery Scale was used to evaluate the level of injury. The PEG fusion group was compared to patient-matched controls whose data were retrospectively collected. RESULTS Four PEG fusions were performed on four nerve transections in two patients. Polyethylene glycol therapy improves functional outcomes and speed of nerve recovery in clinical setting assessed by average MRCC score in week 1 (2.8 vs 1.0, p = 0.03). At 4 weeks, MRCC remained superior in the PEG fusion group (3.8 vs 1.3, p = 0.01). At 8 weeks, there was improvement in both groups with the PEG fusion cohort remaining statistically better (4.0 vs 1.7, p = 0.01). CONCLUSION Polyethylene glycol fusion is a novel therapy for peripheral nerve repair with proven effectiveness in animal models. Clinical studies are still in early stages but have had encouraging results. Polyethylene glycol fusion is a potential revolutionary therapy in peripheral nerve repair but needs further investigation. LEVEL OF EVIDENCE Therapeutic study, level IV.
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42
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Bamba R, Riley DC, Boyer RB, Pollins AC, Shack RB, Thayer WP. Polyethylene glycol restores axonal conduction after corpus callosum transection. Neural Regen Res 2017; 12:757-760. [PMID: 28616031 PMCID: PMC5461612 DOI: 10.4103/1673-5374.206645] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Polyethylene glycol (PEG) has been shown to restore axonal continuity after peripheral nerve transection in animal models. We hypothesized that PEG can also restore axonal continuity in the central nervous system. In this current experiment, coronal sectioning of the brains of Sprague-Dawley rats was performed after animal sacrifice. 3Brain high-resolution microelectrode arrays (MEA) were used to measure mean firing rate (MFR) and peak amplitude across the corpus callosum of the ex-vivo brain slices. The corpus callosum was subsequently transected and repeated measurements were performed. The cut ends of the corpus callosum were still apposite at this time. A PEG solution was applied to the injury site and repeated measurements were performed. MEA measurements showed that PEG was capable of restoring electrophysiology signaling after transection of central nerves. Before injury, the average MFRs at the ipsilateral, midline, and contralateral corpus callosum were 0.76, 0.66, and 0.65 spikes/second, respectively, and the average peak amplitudes were 69.79, 58.68, and 49.60 μV, respectively. After injury, the average MFRs were 0.71, 0.14, and 0.25 spikes/second, respectively and peak amplitudes were 52.11, 8.98, and 16.09 μV, respectively. After application of PEG, there were spikes in MFR and peak amplitude at the injury site and contralaterally. The average MFRs were 0.75, 0.55, and 0.47 spikes/second at the ipsilateral, midline, and contralateral corpus callosum, respectively and peak amplitudes were 59.44, 45.33, 40.02 μV, respectively. There were statistically differences in the average MFRs and peak amplitudes between the midline and non-midline corpus callosum groups (P < 0.01, P < 0.05). These findings suggest that PEG restores axonal conduction between severed central nerves, potentially representing axonal fusion.
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Affiliation(s)
- Ravinder Bamba
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA.,Department of Surgery, Georgetown University, Washington, DC, USA
| | - D Colton Riley
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA.,Georgetown University School of Medicine, Washington, DC, USA
| | - Richard B Boyer
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Alonda C Pollins
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - R Bruce Shack
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Wesley P Thayer
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
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43
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Hoffman AN, Bamba R, Pollins AC, Thayer WP. Analysis of polyethylene glycol (PEG) fusion in cultured neuroblastoma cells via flow cytometry: Techniques & optimization. J Clin Neurosci 2016; 36:125-128. [PMID: 27825612 DOI: 10.1016/j.jocn.2016.10.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 10/15/2016] [Indexed: 12/15/2022]
Abstract
Polyethylene glycol (PEG) has long been used as a membrane fusogen, but recently it has been adopted as a technique for peripheral nerve repair. Vertebrate models using PEG fusion have shown improved outcomes when PEG is applied during repair of severed peripheral nerves. The cellular mechanism of PEG fusion in the peripheral nerve repair model has not previously been assessed via flow cytometry. PEG fusion was assessed in this experiment by dying B35 rat neuroblastoma cells with different color fluorescent labels. The different color cells were combined and PEG was applied in concentrations of 50%, 75% and 100%. The amount of cell fusion was assessed via flow cytometry as the percentage of double positive cells. Results showed increasing fusion and decreasing viability with increasing concentrations of PEG.
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Affiliation(s)
- Ashley N Hoffman
- Vanderbilt School of Medicine, 1161 21st Ave S # T1217, Nashville, TN 37232, United States.
| | - Ravinder Bamba
- Department of Plastic Surgery, Vanderbilt University Medical Center, 1161 21st Ave South, MCN S-2221, Nashville, TN, United States.
| | - Alonda C Pollins
- Department of Plastic Surgery, Vanderbilt University Medical Center, 1161 21st Ave South, MCN S-2221, Nashville, TN, United States.
| | - Wesley P Thayer
- Department of Plastic Surgery, Vanderbilt University Medical Center, 1161 21st Ave South, MCN S-2221, Nashville, TN, United States.
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44
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Bittner GD, Spaeth CS, Poon AD, Burgess ZS, McGill CH. Repair of traumatic plasmalemmal damage to neurons and other eukaryotic cells. Neural Regen Res 2016; 11:1033-42. [PMID: 27630671 PMCID: PMC4994430 DOI: 10.4103/1673-5374.187019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The repair (sealing) of plasmalemmal damage, consisting of small holes to complete transections, is critical for cell survival, especially for neurons that rarely regenerate cell bodies. We first describe and evaluate different measures of cell sealing. Some measures, including morphological/ultra-structural observations, membrane potential, and input resistance, provide very ambiguous assessments of plasmalemmal sealing. In contrast, measures of ionic current flow and dye barriers can, if appropriately used, provide more accurate assessments. We describe the effects of various substances (calcium, calpains, cytoskeletal proteins, ESCRT proteins, mUNC-13, NSF, PEG) and biochemical pathways (PKA, PKC, PLC, Epac, cytosolic oxidation) on plasmalemmal sealing probability, and suggest that substances, pathways, and cellular events associated with plasmalemmal sealing have undergone a very conservative evolution. During sealing, calcium ion influx mobilizes vesicles and other membranous structures (lysosomes, mitochondria, etc.) in a continuous fashion to form a vesicular plug that gradually restricts diffusion of increasingly smaller molecules and ions over a period of seconds to minutes. Furthermore, we find no direct evidence that sealing occurs through the collapse and fusion of severed plasmalemmal leaflets, or in a single step involving the fusion of one large wound vesicle with the nearby, undamaged plasmalemma. We describe how increases in perikaryal calcium levels following axonal transection account for observations that cell body survival decreases the closer an axon is transected to the perikaryon. Finally, we speculate on relationships between plasmalemmal sealing, Wallerian degeneration, and the ability of polyethylene glycol (PEG) to seal cell membranes and rejoin severed axonal ends – an important consideration for the future treatment of trauma to peripheral nerves. A better knowledge of biochemical pathways and cytoplasmic structures involved in plasmalemmal sealing might provide insights to develop treatments for traumatic nerve injuries, stroke, muscular dystrophy, and other pathologies.
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Affiliation(s)
- George D Bittner
- Department of Neuroscience, The University of Texas at Austin, Austin, TX, USA
| | | | - Andrew D Poon
- Department of Neuroscience, The University of Texas at Austin, Austin, TX, USA
| | - Zachary S Burgess
- Department of Neuroscience, The University of Texas at Austin, Austin, TX, USA
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45
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Bittner GD, Sengelaub DR, Trevino RC, Ghergherehchi CL, Mikesh M. Robinson and madison have published no data on whether polyethylene glycol fusion repair prevents reinnervation accuracy in rat peripheral nerve. J Neurosci Res 2016; 95:863-866. [PMID: 27514994 DOI: 10.1002/jnr.23849] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 06/20/2016] [Accepted: 07/05/2016] [Indexed: 12/26/2022]
Affiliation(s)
- G D Bittner
- Department of Neuroscience, University of Texas at Austin, Austin, Texas
| | - D R Sengelaub
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana
| | - R C Trevino
- Department of Orthopedic Surgery, Wellspan Health, York, Pennsylvania
| | - C L Ghergherehchi
- Department of Neuroscience, University of Texas at Austin, Austin, Texas
| | - M Mikesh
- Department of Neuroscience, University of Texas at Austin, Austin, Texas
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46
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Robinson GA, Madison RD. The title and data of Robinson and Madison (2016) are valid. J Neurosci Res 2016; 95:867-868. [PMID: 27510502 DOI: 10.1002/jnr.23867] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 07/12/2016] [Accepted: 07/13/2016] [Indexed: 12/15/2022]
Affiliation(s)
- Grant A Robinson
- Department of Neurosurgery, Duke University Medical Center, Durham, North Carolina
| | - Roger D Madison
- Department of Neurosurgery, Duke University Medical Center, Durham, North Carolina.,Biological Laboratory Research and Development Service, Veterans Affairs Medical Center, Durham, North Carolina
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47
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Bamba R, Riley DC, Kelm ND, Does MD, Dortch RD, Thayer WP. A novel technique using hydrophilic polymers to promote axonal fusion. Neural Regen Res 2016; 11:525-8. [PMID: 27212898 PMCID: PMC4870894 DOI: 10.4103/1673-5374.180724] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The management of traumatic peripheral nerve injury remains a considerable concern for clinicians. With minimal innovations in surgical technique and a limited number of specialists trained to treat peripheral nerve injury, outcomes of surgical intervention have been unpredictable. The inability to manipulate the pathophysiology of nerve injury (i.e., Wallerian degeneration) has left scientists and clinicians depending on the slow and lengthy process of axonal regeneration (~1 mm/day). When axons are severed, the endings undergo calcium-mediated plasmalemmal sealing, which limits the ability of the axon to be primarily repaired. Polythethylene glycol (PEG) in combination with a bioengineered process overcomes the inability to fuse axons. The mechanism for PEG axonal fusion is not clearly understood, but multiple studies have shown that a providing a calcium-free environment is essential to the process known as PEG fusion. The proposed mechanism is PEG-induced lipid bilayer fusion by removing the hydration barrier surrounding the axolemma and reducing the activation energy required for membrane fusion to occur. This review highlights PEG fusion, its past and current studies, and future directions in PEG fusion.
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Affiliation(s)
- Ravinder Bamba
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Surgery, Georgetown University, Washington, DC, USA
| | - D Colton Riley
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA; Georgetown University School of Medicine, Washington, DC, USA
| | - Nathaniel D Kelm
- Vanderbilt University Institute of Imaging Science, Nashville, TN, USA
| | - Mark D Does
- Vanderbilt University Institute of Imaging Science, Nashville, TN, USA
| | - Richard D Dortch
- Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Wesley P Thayer
- Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
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48
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Canavero S, Ren X, Kim CY, Rosati E. Neurologic foundations of spinal cord fusion (GEMINI). Surgery 2016; 160:11-19. [PMID: 27180142 DOI: 10.1016/j.surg.2016.01.027] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 01/08/2016] [Accepted: 01/21/2016] [Indexed: 12/17/2022]
Abstract
Cephalosomatic anastomosis has been carried out in both monkeys and mice with preservation of brain function. Nonetheless the spinal cord was not reconstructed, leaving the animals unable to move voluntarily. Here we review the details of the GEMINI spinal cord fusion protocol, which aims at restoring electrophysiologic conduction across an acutely transected spinal cord. The existence of the cortico-truncoreticulo-propriospinal pathway, a little-known anatomic entity, is described, and its importance concerning spinal cord fusion emphasized. The use of fusogens and electrical stimulation as adjuvants for nerve fusion is addressed. The possibility of achieving cephalosomatic anastomosis in humans has become reality in principle.
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Affiliation(s)
| | - XiaoPing Ren
- Hand and Microsurgical Center, the Second Affiliated Hospital of Harbin Medical University; State-Province Key Laboratories of Biomedicine-Pharmaceutics, Harbin Medical University, Harbin, China; Department of Molecular Pharmacology and Therapeutics, Stritch School of Medicine, Loyola University Chicago, Chicago, IL
| | - C-Yoon Kim
- Department of Bioengineering, College of Life Science, CHA University, Seoul, Korea; Department of Laboratory Animal Medicine, College of Veterinary Medicine, Seoul National University, Seoul, Korea
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Bittner GD, Mikesh M, Ghergherehchi CL. Polyethylene glycol-fusion retards Wallerian degeneration and rapidly restores behaviors lost after nerve severance. Neural Regen Res 2016; 11:217-9. [PMID: 27073362 PMCID: PMC4810973 DOI: 10.4103/1673-5374.177716] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
- George D Bittner
- Department of Neuroscience, University of Texas at Austin, Austin, TX, USA
| | - Michelle Mikesh
- Department of Neuroscience, University of Texas at Austin, Austin, TX, USA
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50
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Robinson GA, Madison RD. Polyethylene glycol fusion repair prevents reinnervation accuracy in rat peripheral nerve. J Neurosci Res 2016; 94:636-44. [PMID: 26994857 DOI: 10.1002/jnr.23734] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 02/08/2016] [Accepted: 02/28/2016] [Indexed: 11/12/2022]
Abstract
Functional recovery following a peripheral nerve injury is made easier when regenerating axons correctly reinnervate their original targets. Polyethylene glycol (PEG) has recently been used in attempts to fuse severed peripheral axons during suture-based repair, but an analysis of target selectivity following such repair has not been undertaken. The rat femoral nerve (in which muscle and cutaneous pathways comingle proximally but segregate distally into separate terminal nerve branches) is a convenient in vivo model for assessing motor neuron regeneration accuracy. The present study uses retrograde labeling of motor neurons to compare reinnervation accuracy after suture-based nerve repair with and without PEG fusion. The results show that adding PEG to the suture repair site blocked the preference of motor neurons to reinnervate correctly the distal terminal nerve branch to muscle that was seen with suture repair. Retrograde transport and diffusion studies also determined that PEG fusion allowed passage of probes across the repair site, as has previously been seen, but did not result in motor neuron labeling in the spinal cord. The results suggest that PEG fusion disrupts the beneficial trophic influence of muscle on motor neuron reinnervation accuracy normally seen after suture repair and that such fusion-based approaches may be best suited to nerve injuries in which accurate target reinnervation at the terminal nerve branch level is not a priority. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Grant A Robinson
- Department of Neurosurgery, Duke University Medical Center, Durham, North Carolina
| | - Roger D Madison
- Department of Neurosurgery, Duke University Medical Center, Durham, North Carolina.,Biological Laboratory Research and Development Service, Veterans Affairs Medical Center, Durham, North Carolina
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