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Pardo ID, Rao DB, Morrison JP, Huddleston C, Bradley AE, Bolon B, Garman RH. Nervous System Sampling for General Toxicity and Neurotoxicity Studies in Rabbits. Toxicol Pathol 2020; 48:810-826. [PMID: 33094688 DOI: 10.1177/0192623320957637] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Although manuscripts for multiple species recommending nervous system sampling for histopathology evaluation in safety assessment have been published in the past 15 years, none have addressed the laboratory rabbit. Here, we describe 2 trimming schemes for evaluating the rabbit brain in nonclinical toxicity studies. In both schemes, the intact brain is cut in the coronal plane to permit bilateral assessment. The first scheme is recommended for general toxicity studies (tier 1) in screening agents where there is no anticipated neurotoxic potential; this 6-section approach is consistent with the Society of Toxicologic Pathology (STP) "best practice" recommendations for brain sampling in nonrodents (Toxicol Pathol 41: 1028-1048, 20131). The second trimming scheme is intended for dedicated neurotoxicity studies (tier 2) to characterize known or suspected neurotoxicants where the nervous system is a key target organ. This tier 2 strategy relies on coronal trimming of the whole brain into 3-mm-thick slices and then evaluating 12 sections. Collection of spinal cord, ganglia, and nerve specimens for rabbits during nonclinical studies should follow published STP "best practice" recommendations for sampling the central nervous system1 and peripheral nervous system (Toxicol Pathol 46: 372-402, 20182).
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Affiliation(s)
- Ingrid D Pardo
- 390190Pfizer, Inc, Global Pathology and Investigative Toxicology, Groton, CT, USA
| | - Deepa B Rao
- ToxPath Specialists, LLC (a StageBio Company), Frederick, MD, USA
| | | | - Colleen Huddleston
- 390190Pfizer, Inc, Global Pathology and Investigative Toxicology, Groton, CT, USA
| | - Alys E Bradley
- 57146Charles River Laboratories Edinburgh Ltd, Tranent, East Lothian, Scotland, United Kingdom
| | | | - Robert H Garman
- Consultants in Veterinary Pathology, Inc, Murrysville, Pennsylvania, PA, USA
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2
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Wang ZY, Wang JW, Qin LH, Zhang WG, Zhang PX, Jiang BG. Chitin biological absorbable catheters bridging sural nerve grafts transplanted into sciatic nerve defects promote nerve regeneration. CNS Neurosci Ther 2018; 24:483-494. [PMID: 29424054 DOI: 10.1111/cns.12820] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 12/23/2017] [Accepted: 01/15/2018] [Indexed: 01/15/2023] Open
Abstract
AIMS To investigate the efficacy of chitin biological absorbable catheters in a rat model of autologous nerve transplantation. METHODS A segment of sciatic nerve was removed to produce a sciatic nerve defect, and the sural nerve was cut from the ipsilateral leg and used as a graft to bridge the defect, with or without use of a chitin biological absorbable catheter surrounding the graft. The number and morphology of regenerating myelinated fibers, nerve conduction velocity, nerve function index, triceps surae muscle morphology, and sensory function were evaluated at 9 and 12 months after surgery. RESULTS All of the above parameters were improved in rats in which the nerve graft was bridged with chitin biological absorbable catheters compared with rats without catheters. CONCLUSIONS The results of this study indicate that use of chitin biological absorbable catheters to surround sural nerve grafts bridging sciatic nerve defects promotes recovery of structural, motor, and sensory function and improves muscle fiber morphology.
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Affiliation(s)
- Zhi-Yong Wang
- Department of Anatomy and Histo-embryology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Jian-Wei Wang
- Department of Anatomy and Histo-embryology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Li-Hua Qin
- Department of Anatomy and Histo-embryology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Wei-Guang Zhang
- Department of Anatomy and Histo-embryology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Pei-Xun Zhang
- Department of Trauma and Orthopedics, Peking University People's Hospital, Beijing, China
| | - Bao-Guo Jiang
- Department of Trauma and Orthopedics, Peking University People's Hospital, Beijing, China
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3
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Vein wrapping technique for nerve reconstruction in patients with thyroid cancer invading the recurrent laryngeal nerve. Arch Plast Surg 2012; 39:71-5. [PMID: 22783497 PMCID: PMC3385298 DOI: 10.5999/aps.2012.39.1.71] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 12/19/2011] [Accepted: 12/19/2011] [Indexed: 11/08/2022] Open
Abstract
Recurrent laryngeal nerve paralysis is the most common and serious complication after thyroid cancer surgery. The objective of this study was to report the advantages of the vein wrapping technique for nerve reconstruction in patients with thyroid cancer invading the recurrent laryngeal nerve and its effects on postoperative phonatory function. The subjects were three patients who underwent resection of the recurrent laryngeal nerve during surgical extirpation of papillary thyroid cancer. Free ansa cervicalis nerve graft or direct neurorrhaphy with a vein wrapping technique was used to facilitate nerve regeneration, protect the anastomosed nerve site mechanically, and prevent neuroma formation. One-year postoperative laryngoscopic examination revealed good vocal cord mobility. Maximum phonation time (19.5 ± 0.3 sec) was longer than a previously-reported value in conventional reconstruction patients (18.8 ± 6.6 sec). The present phonation efficiency index (7.88 ± 0.78) was higher than that previously calculated in conventional reconstruction (7.59 ± 2.82). The mean value of the Voice Handicap Index-10 was 6, which was within the normal range. This study demonstrates improvement in phonation indices measured 1 year after recurrent laryngeal nerve reconstruction. Our results confirm that the vein wrapping technique has theoretical advantages and could be favored over conventional reconstruction techniques for invenerate nerve injuries.
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Giusti G, Kremer T, Willems WF, Friedrich PF, Bishop AT, Shin AY. Description and validation of isometric tetanic muscle force test in rabbits. Microsurgery 2011; 32:35-42. [DOI: 10.1002/micr.20941] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Accepted: 06/20/2011] [Indexed: 01/18/2023]
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Barras FM, Kuntzer T, Zurn AD, Pasche P. Local delivery of glial cell line-derived neurotrophic factor improves facial nerve regeneration after late repair. Laryngoscope 2009; 119:846-55. [PMID: 19266571 DOI: 10.1002/lary.20169] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
OBJECTIVES/HYPOTHESIS Facial nerve regeneration is limited in some clinical situations: in long grafts, by aged patients, and when the delay between nerve lesion and repair is prolonged. This deficient regeneration is due to the limited number of regenerating nerve fibers, their immaturity and the unresponsiveness of Schwann cells after a long period of denervation. This study proposes to apply glial cell line-derived neurotrophic factor (GDNF) on facial nerve grafts via nerve guidance channels to improve the regeneration. METHODS Two situations were evaluated: immediate and delayed grafts (repair 7 months after the lesion). Each group contained three subgroups: a) graft without channel, b) graft with a channel without neurotrophic factor; and c) graft with a GDNF-releasing channel. A functional analysis was performed with clinical observation of facial nerve function, and nerve conduction study at 6 weeks. Histological analysis was performed with the count of number of myelinated fibers within the graft, and distally to the graft. Central evaluation was assessed with Fluoro-Ruby retrograde labeling and Nissl staining. RESULTS This study showed that GDNF allowed an increase in the number and the maturation of nerve fibers, as well as the number of retrogradely labeled neurons in delayed anastomoses. On the contrary, after immediate repair, the regenerated nerves in the presence of GDNF showed inferior results compared to the other groups. CONCLUSIONS GDNF is a potent neurotrophic factor to improve facial nerve regeneration in grafts performed several months after the nerve lesion. However, GDNF should not be used for immediate repair, as it possibly inhibits the nerve regeneration.
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Affiliation(s)
- Florian M Barras
- Department of Otorhinolaryngology, CHU Vaudois and University of Lausanne, Lausanne, Switzerland.
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Unezaki S, Yoshii S, Mabuchi T, Saito A, Ito S. Effects of neurotrophic factors on nerve regeneration monitored by in vivo imaging in thy1-YFP transgenic mice. J Neurosci Methods 2009; 178:308-15. [DOI: 10.1016/j.jneumeth.2008.12.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Revised: 12/16/2008] [Accepted: 12/19/2008] [Indexed: 01/15/2023]
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Bettinger CJ, Bruggeman JP, Misra A, Borenstein JT, Langer R. Biocompatibility of biodegradable semiconducting melanin films for nerve tissue engineering. Biomaterials 2009; 30:3050-7. [PMID: 19286252 DOI: 10.1016/j.biomaterials.2009.02.018] [Citation(s) in RCA: 215] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Accepted: 02/12/2009] [Indexed: 11/29/2022]
Abstract
The advancement of tissue engineering is contingent upon the development and implementation of advanced biomaterials. Conductive polymers have demonstrated potential for use as a medium for electrical stimulation, which has shown to be beneficial in many regenerative medicine strategies including neural and cardiac tissue engineering. Melanins are naturally occurring pigments that have previously been shown to exhibit unique electrical properties. This study evaluates the potential use of melanin films as a semiconducting material for tissue engineering applications. Melanin thin films were produced by solution processing and the physical properties were characterized. Films were molecularly smooth with a roughness (R(ms)) of 0.341 nm and a conductivity of 7.00+/-1.10 x 10(-5)S cm(-1) in the hydrated state. In vitro biocompatibility was evaluated by Schwann cell attachment and growth as well as neurite extension in PC12 cells. In vivo histology was evaluated by examining the biomaterial-tissue response of melanin implants placed in close proximity to peripheral nerve tissue. Melanin thin films enhanced Schwann cell growth and neurite extension compared to collagen films in vitro. Melanin films induced an inflammation response that was comparable to silicone implants in vivo. Furthermore, melanin implants were significantly resorbed after 8 weeks. These results suggest that solution-processed melanin thin films have the potential for use as a biodegradable semiconducting biomaterial for use in tissue engineering applications.
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Affiliation(s)
- Christopher J Bettinger
- Department of Chemical Engineering, Stanford University, 381 North South Mall, Stauffer III, Room 113, Stanford, CA, USA
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Yan H, Zhang F, Chen MB, Lineaweaver WC. Chapter 10 Conduit Luminal Additives for Peripheral Nerve Repair. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2009; 87:199-225. [DOI: 10.1016/s0074-7742(09)87010-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Piskin A, Kaplan S, Aktaş A, Ayyildiz M, Raimondo S, Aliç T, Bozkurt HH, Geuna S. Platelet gel does not improve peripheral nerve regeneration: An electrophysiological, stereological, and electron microscopic study. Microsurgery 2008; 29:144-53. [DOI: 10.1002/micr.20599] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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10
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Di Benedetto G, Grassetti L, Mazzucchelli R, Scarpelli M, Bertani A. Peripheral nerve regeneration: autologous conduit of vein plus perineurium. EUROPEAN JOURNAL OF PLASTIC SURGERY 2008. [DOI: 10.1007/s00238-008-0302-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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O'Neill AC, Randolph MA, Bujold KE, Kochevar IE, Redmond RW, Winograd JM. Photochemical sealing improves outcome following peripheral neurorrhaphy. J Surg Res 2008; 151:33-9. [PMID: 18599081 DOI: 10.1016/j.jss.2008.01.025] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2007] [Revised: 01/10/2008] [Accepted: 01/18/2008] [Indexed: 01/14/2023]
Abstract
INTRODUCTION Peripheral nerve transection initiates a complex molecular response in the severed nerve endings, resulting in the release of neurotrophic and neurotropic factors that are central to axonal survival and regeneration. In this study we tested the hypothesis that sealing the neurorrhaphy site from the surrounding environment using a photochemically bonded nerve wrap would optimize the endoneural environment and enhance regeneration and nerve function recovery. MATERIALS AND METHODS Adult rats underwent unilateral sciatic nerve transection and standard epineural nerve repair. The repair site was wrapped with amniotic membrane or autologous vein and then was either sealed using photochemical tissue bonding (PTB) or secured with sutures. Photochemical sealing without a wrap was also carried out. Functional recovery was assessed at 2-wk intervals using walking track analysis and nerve histomorphometry was assessed at 12 wk. RESULTS Treating nerves with PTB-sealed amnion significantly improved functional recovery and increased distal axon and fiber diameters and myelin thickness compared to nerves treated with standard neurorrhaphy alone. Direct PTB sealing of the repair site also improved function. Neither amnion secured with sutures nor vein wraps exhibited improved functional or histological recovery compared to standard neurorrhaphy. CONCLUSIONS These results suggest that sealing the peripheral nerve repair site with amnion using a photochemical technique may lead to earlier restoration of neural homeostasis and consequent enhanced repair of nerve injury.
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Affiliation(s)
- Anne C O'Neill
- Plastic Surgery Research Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA
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12
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Pfister LA, Papaloïzos M, Merkle HP, Gander B. Nerve conduits and growth factor delivery in peripheral nerve repair. J Peripher Nerv Syst 2007; 12:65-82. [PMID: 17565531 DOI: 10.1111/j.1529-8027.2007.00125.x] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Peripheral nerves possess the capacity of self-regeneration after traumatic injury. Transected peripheral nerves can be bridged by direct surgical coaptation of the two nerve stumps or by interposing autografts or biological (veins) or synthetic nerve conduits (NC). NC are tubular structures that guide the regenerating axons to the distal nerve stump. Early synthetic NC have primarily been made of silicone because of the relative flexibility and biocompatibility of this material and because medical-grade silicone tubes were readily available in various dimensions. Nowadays, NC are preferably made of biodegradable materials such as collagen, aliphatic polyesters, or polyurethanes. Although NC assist in guiding regenerating nerves, satisfactory functional restoration of severed nerves may further require exogenous growth factors. Therefore, authors have proposed NC with integrated delivery systems for growth factors or growth factor-producing cells. This article reviews the most important designs of NC with integrated delivery systems for localized release of growth factors. The various systems discussed comprise NC with growth factors being released from various types of matrices, from transplanted cells (Schwann cells or mesenchymal stem cells), or through genetic modification of cells naturally present at the site of injured tissue. Acellular delivery systems for growth factors include the NC wall itself, biodegradable microspheres seeded onto the internal surface of the NC wall, or matrices that are filled into the lumen of the NC and immobilize the growth factors through physical-chemical interactions or specific ligand-receptor interactions. A very promising and elegant system appears to be longitudinally aligned fibers inserted in the lumen of a NC that deliver the growth factors and provide additional guidance for Schwann cells and axons. This review also attempts to appreciate the most promising approaches and emphasize the importance of growth factor delivery kinetics.
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Affiliation(s)
- Lukas A Pfister
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
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13
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Clavijo-Alvarez JA, Nguyen VT, Santiago LY, Doctor JS, Lee WPA, Marra KG. Comparison of Biodegradable Conduits within Aged Rat Sciatic Nerve Defects. Plast Reconstr Surg 2007; 119:1839-1851. [PMID: 17440364 DOI: 10.1097/01.prs.0000260232.43019.a0] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Considering that little is known about the peripheral nerve regenerative capacity of elderly patients, the authors studied nerve regenerative capacity in aged rats and compared the effect of three synthetic nerve guides with different material characteristics and porosity. The authors hypothesized that the use of a biodegradable composite nerve guide (CultiGuides) would promote nerve regeneration and functional recovery in a manner similar to treatment with autografts or U.S. Food and Drug Administration-approved polyglycolic acid Neurotubes in an aged rat sciatic nerve defect model. METHODS Aged Sprague-Dawley rats (11 months old) underwent a 1-cm sciatic nerve resection in the right leg [group 1, control (contralateral leg samples), n = 10; group 2, negative (nerve gap defect), n = 6; group 3, autograft, n = 10; group 4, polycaprolactone, n = 10; group 5, CultiGuides, n = 10; and group 6, Neurotube, n = 10]. RESULTS After 12 weeks, the negative group did not demonstrate any nerve regeneration. In the regenerated and distal nerve, all treated groups had increased myelinated areas compared with the negative control. In the regenerated nerve, there was a significant increase in myelination in the Neurotube group compared with the polycaprolactone group (p < 0.001). However, in the distal nerve, there were no differences among the treatment groups. Walking track analyses and gastrocnemius muscle weight ratios were not different among treatment groups 3 through 6. CONCLUSIONS The results showed differences in myelination; Neurotubes promoted the highest degree of myelination (p < 0.001) as compared with all groups. The authors found no improvement in function of the repaired nerve as measured by percentage of autotomy, the sciatic function index, and gastrocnemius muscle weight. No group was able to recover function in this aged model.
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Affiliation(s)
- Julio A Clavijo-Alvarez
- Pittsburgh, Pa. From the Division of Plastic and Reconstructive Surgery and Department of Bioengineering, University of Pittsburgh; Department of Biological Sciences, Duquesne University; and McGowan Institute for Regenerative Medicine
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Abstract
The use of nerve conduits as an alternative for nerve grafting has a long experimental and clinical history. Luminal fillers, factors introduced into these nerve conduits, were later developed to enhance the nerve regeneration through conduits. Though many luminal fillers have been reported to improve nerve regeneration, their use has not been subjected to systematic review. This review categorizes the types of fillers used, the conduits associated with fillers, and the reported performance of luminal fillers in conduits to present a preference list for the most effective fillers to use over specific distances of nerve defect.
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Affiliation(s)
- Michael B Chen
- Division of Plastic Surgery, University of Mississippi Medical Center, Jackson, MS 39216, USA
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Lutz BS, Lidman D. Morphological and functional evaluation of leg-muscle reinnervation after coupler coaptation of the divided rat sciatic nerve. Microsurgery 2005; 25:235-40. [PMID: 15696517 DOI: 10.1002/micr.20102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Mechanical couplers are successfully used for microvascular venous anastomoses. The advantages include a simple and fast technique and a high patency rate. Couplers offer a secluded coaptation site, and might also be of use in peripheral nerve repair. The present study was designed to investigate coupler coaptation of the rat sciatic nerve, evaluating the number and locations of motor and sensory neurons projecting to the selected muscles as well as stimulation-induced muscle contraction force. Adult rats underwent either suture or coupler repair after left sciatic nerve transection. In all rats, the experimental side was compared to the healthy right side. Evaluation after 20 weeks included retrograde labeling of motoneurons and dorsal root ganglion neurons projecting to the tibial anterior muscle and to the tibial posterior muscle, histology, muscle contraction force (tibial anterior muscle and gastrocnemius muscle), and a pinch reflex test. The results show that the suture and the coupler groups did not differ significantly regarding the examined parameters, except for discrete signs of nerve compression at the coaptation site after coupler repair due to fibrous tissue ingrowth. However, this did not impair axonal regeneration. Importantly, axonal outgrowth from the repair site to the surrounding tissue was not observed after coupler coaptation, but it was observed after suture repair. These results suggest that couplers may be of value for repair of nerves in adjacency to avoid axonal crisscrossing between nerves during regeneration.
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Affiliation(s)
- Barbara S Lutz
- Department of Plastic Surgery, University Hospital Orebro, Orebro, Sweden.
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Vince V, Thil MA, Veraart C, Colin IM, Delbeke J. Biocompatibility of platinum-metallized silicone rubber: in vivo and in vitro evaluation. JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION 2004; 15:173-88. [PMID: 15109096 DOI: 10.1163/156856204322793566] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Silicone rubber is commonly used for biomedical applications, including implanted cuff electrodes for both recording and stimulation of peripheral nerves. This study was undertaken to evaluate the consequences of a new platinum metallization method on the biocompatibility of silicone rubber cuff electrodes. This method was introduced in order to allow the manufacture of spiral nerve cuff electrodes with a large number of contacts. The metallization process, implying silicone coating with poly(methyl methacrylate) (PMMA), its activation by an excimer laser and subsequent electroless metal deposition, led to a new surface microtexture. The neutral red cytotoxicity assay procedure was first applied in vitro on BALB/c 3T3 fibroblasts in order to analyze the cellular response elicited by the studied material. An in vivo assay was then performed to investigate the tissue reaction after chronic subcutaneous implantation of the metallized material. Results demonstrate that silicone rubber biocompatibility is not altered by the new platinum metallization method.
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Affiliation(s)
- V Vince
- Neural Rehabilitation Engineering Laboratory, Université catholique de Louvain, Faculty of Medicine, Department of Physiology and Pharmacology, Avenue Hippocrate 54, B-1200 Brussels, Belgium
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Schmidhammer R, Zandieh S, Hopf R, Mizner I, Pelinka LE, Kroepfl A, Redl H. Alleviated tension at the repair site enhances functional regeneration: the effect of full range of motion mobilization on the regeneration of peripheral nerves--histologic, electrophysiologic, and functional results in a rat model. ACTA ACUST UNITED AC 2004; 56:571-84. [PMID: 15128129 DOI: 10.1097/01.ta.0000114082.19295.e6] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND In the clinical management of combined tendon and nerve injuries, competing treatment strategies are well known. The effect of mobilization on the functional regeneration of peripheral nerves remains controversial. This study sought to determine the effect of full range of motion mobilization on nerve repair by using tubular segmental nerve splinting to block movement, and thereby variable tension, at the nerve repair site. METHODS In 96 rats, the right sciatic nerve was transected midthigh and coapted immediately microsurgically. The groups used in the study were as follows: group N, epineural nerve repair; group T, segmental tubular nerve splinting with fixed in situ tension at the nerve suture site,allowing segmental movement only; group TN, segmental tubular nerve splinting with alleviated in situ tension at the nerve suture site, allowing segmental movement only; and group TM, segmental tubular nerve splinting without fixed in situ tension at the nerve suture site, allowing movement of the nerve suture site. Full range of motion of the lower limbs was ensured by passive motion of hind limbs once a week after functional testing. Blinded histologic, immunohistochemical, and electrophysiologic assessment and 12 postoperative weekly function tests were carried out. RESULTS Functional and electrophysiologic results were significantly better in group TN, by segmental tubular nerve splinting with alleviated in situ tension at the nerve repair site, mainly because of less scar formation and enhanced endoneural angiogenesis at the nerve suture segment. CONCLUSION Full range of motion mobilization may impede functional nerve recovery by significant endoneural collagenization and decreased angiogenesis at the nerve suture segment. Complete alleviation of in situ (pathophysiologic) tension at the nerve suture site seems to improve functional peripheral nerve regeneration.
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Affiliation(s)
- Robert Schmidhammer
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Research Center for Traumatology of the AUVA, Donaueschingenstrasse 13, A-1200 Vienna, Austria.
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Ai H, Meng H, Ichinose I, Jones SA, Mills DK, Lvov YM, Qiao X. Biocompatibility of layer-by-layer self-assembled nanofilm on silicone rubber for neurons. J Neurosci Methods 2003; 128:1-8. [PMID: 12948543 DOI: 10.1016/s0165-0270(03)00191-2] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Electrostatic layer-by-layer (LbL) self-assembly, a novel method for ultrathin film coating has been applied to silicone rubber to encourage nerve cell adhesion. The surfaces studied consisted of precursor layers, with alternating cationic poly(ethyleneimine) (PEI) and anionic sodium poly(styrenesulfonate) (PSS) followed by alternating laminin and poly-D-lysine (PDL) layers or fibronectin and PDL layers. Film growth increased linearly with the number of layers. Every fibronectin/PDL and laminin/PDL bilayer was 4.4 and 3.5 nm thick, respectively. All layers were more hydrophilic than the unmodified silicone rubber surface, as determined from contact angle measurements. Of the coatings studied, a PDL layer was the most hydrophilic. A multilayer film with composition [PSS/PEI]3+[fibronectin/PDL]4 or [PSS/PEI]3+[laminin/PDL]4 was highly favorable for neuron adhesion, in contrast to bare silicone rubber substrate. The film coated on silicone rubber is biocompatible for cerebellar neurons with active viability, as shown by lactate dehydrogenase (LDH) assay and fluorescence cellular metabolism observations. These results demonstrate that LbL self-assembly provides an effective approach to apply films with nanometer thickness to silicone rubber. Such only few nanometer thick films are biocompatible with neurons, and may be used to coat devises for long-term implant in the central nervous system.
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Affiliation(s)
- Hua Ai
- Department of Biomedical Engineering and Institute for Micromanufacturing, Louisiana Tech University, Ruston, LA 71272, USA
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