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Cui JJ, Wang J, Xu DS, Wu S, Guo YT, Su YX, Liu YH, Wang YQ, Jing XH, Bai WZ. Alexa Fluor 488-conjugated cholera toxin subunit B optimally labels neurons 3-7 days after injection into the rat gastrocnemius muscle. Neural Regen Res 2022; 17:2316-2320. [PMID: 35259856 PMCID: PMC9083145 DOI: 10.4103/1673-5374.337055] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Neural tract tracing is used to study neural pathways and evaluate neuronal regeneration following nerve injuries. However, it is not always clear which tracer should be used to yield optimal results. In this study, we examined the use of Alexa Fluor 488-conjugated cholera toxin subunit B (AF488-CTB). This was injected into the gastrocnemius muscle of rats, and it was found that motor, sensory, and sympathetic neurons were labeled in the spinal ventral horn, dorsal root ganglia, and sympathetic chain, respectively. Similar results were obtained when we injected AF594-CTB into the tibialis anterior muscle. The morphology and number of neurons were evaluated at different time points following the AF488-CTB injection. It was found that labeled motor and sensory neurons could be observed 12 hours post-injection. The intensity was found to increase over time, and the morphology appeared clear and complete 3-7 days post-injection, with clearly distinguishable motor neuron axons and dendrites. However, 14 days after the injection, the quality of the images decreased and the neurons appeared blurred and incomplete. Nissl and immunohistochemical staining showed that the AF488-CTB-labeled neurons retained normal neurochemical and morphological features, and the surrounding microglia were also found to be unaltered. Overall, these results imply that the cholera toxin subunit B, whether unconjugated or conjugated with Alexa Fluor, is effective for retrograde tracing in muscular tissues and that it would also be suitable for evaluating the regeneration or degeneration of injured nerves.
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Affiliation(s)
- Jing-Jing Cui
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Jia Wang
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Dong-Sheng Xu
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Shuang Wu
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Ya-Ting Guo
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Yu-Xin Su
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Yi-Han Liu
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Yu-Qing Wang
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Xiang-Hong Jing
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Wan-Zhu Bai
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
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Barham M, Streppel M, Guntinas-Lichius O, Fulgham-Scott N, Vogt J, Neiss WF. Treatment With Nimodipine or FK506 After Facial Nerve Repair Neither Improves Accuracy of Reinnervation Nor Recovery of Mimetic Function in Rats. Front Neurosci 2022; 16:895076. [PMID: 35645727 PMCID: PMC9136327 DOI: 10.3389/fnins.2022.895076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Accepted: 04/25/2022] [Indexed: 11/13/2022] Open
Abstract
Purpose Nimodipine and FK506 (Tacrolimus) are drugs that have been reported to accelerate peripheral nerve regeneration. We therefore tested these substances aiming to improve the final functional outcome of motoric reinnervation after facial nerve injury. Methods In 18 female rats, the transected facial nerve was repaired by an artificial nerve conduit. The rats were then treated with either placebo, nimodipine, or FK506, for 56 days. Facial motoneurons were pre-operatively double-labeled by Fluoro-Gold and again 56 days post-operation by Fast-Blue to measure the cytological accuracy of reinnervation. The whisking motion of the vibrissae was analyzed to assess the quality of functional recovery. Results On the non-operated side, 93–97% of those facial nerve motoneurons innervating the vibrissae were double-labeled. On the operated side, double-labeling only amounted to 38% (placebo), 40% (nimodipine), and 39% (FK506), indicating severe misdirection of reinnervation. Regardless of post-operative drug or placebo therapy, the whisking frequency reached 83–100% of the normal value (6.0 Hz), but whisking amplitude was reduced to 33–48% while whisking velocity reached 39–66% of the normal values. Compared to placebo, statistically neither nimodipine nor FK506 improved accuracy of reinnervation and function recovery. Conclusion Despite previous, positive data on the speed and quantity of axonal regeneration, nimodipine and FK506 do not improve the final functional outcome of motoric reinnervation in rats.
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Affiliation(s)
- Mohammed Barham
- Department II of Anatomy, Faculty of Medicine, University of Cologne and University Hospital of Cologne, Cologne, Germany
- *Correspondence: Mohammed Barham,
| | - Michael Streppel
- Department of Ear, Nose and Throat-Department (ENT), PAN-Clinic at Neumarkt, Cologne, Germany
| | | | - Nicole Fulgham-Scott
- Department I of Anatomy, Faculty of Medicine, University of Cologne and University Hospital of Cologne, Cologne, Germany
| | - Johannes Vogt
- Department II of Anatomy, Faculty of Medicine, University of Cologne and University Hospital of Cologne, Cologne, Germany
| | - Wolfram F. Neiss
- Department I of Anatomy, Faculty of Medicine, University of Cologne and University Hospital of Cologne, Cologne, Germany
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Raslan A, Salem MAM, Al‐Hussaini A, Guntinas‐Lichius O, Irintchev A. Brief Electrical Stimulation Improves Functional Recovery After Femoral But Not After Facial Nerve Injury in Rats. Anat Rec (Hoboken) 2019; 302:1304-1313. [DOI: 10.1002/ar.24127] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 05/08/2018] [Accepted: 09/11/2018] [Indexed: 11/10/2022]
Affiliation(s)
- Ashraf Raslan
- Department of OtorhinolaryngologyJena University Hospital Jena Germany
- Department of OtorhinolaryngologyAssiut University Assiut Egypt
| | | | | | | | - Andrey Irintchev
- Department of OtorhinolaryngologyJena University Hospital Jena Germany
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Nadi M, Ramachandran S, Islam A, Forden J, Guo GF, Midha R. Testing the effectiveness and the contribution of experimental supercharge (reversed) end-to-side nerve transfer. J Neurosurg 2018; 130:702-711. [PMID: 29775143 DOI: 10.3171/2017.12.jns171570] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 12/04/2017] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Supercharge end-to-side (SETS) transfer, also referred to as reverse end-to-side transfer, distal to severe nerve compression neuropathy or in-continuity nerve injury is gaining clinical popularity despite questions about its effectiveness. Here, the authors examined SETS distal to experimental neuroma in-continuity (NIC) injuries for efficacy in enhancing neuronal regeneration and functional outcome, and, for the first time, they definitively evaluated the degree of contribution of the native and donor motor neuron pools. METHODS This study was conducted in 2 phases. In phase I, rats (n = 35) were assigned to one of 5 groups for unilateral sciatic nerve surgeries: group 1, tibial NIC with distal peroneal-tibial SETS; group 2, tibial NIC without SETS; group 3, intact tibial and severed peroneal nerves; group 4, tibial transection with SETS; and group 5, severed tibial and peroneal nerves. Recovery was evaluated biweekly using electrophysiology and locomotion tasks. At the phase I end point, after retrograde labeling, the spinal cords were analyzed to assess the degree of neuronal regeneration. In phase II, 20 new animals underwent primary retrograde labeling of the tibial nerve, following which they were assigned to one of the following 3 groups: group 1, group 2, and group 4. Then, secondary retrograde labeling from the tibial nerve was performed at the study end point to quantify the native versus donor regenerated neuronal pool. RESULTS In phase I studies, a significantly increased neuronal regeneration in group 1 (SETS) compared with all other groups was observed, but with modest (nonsignificant) improvement in electrophysiological and behavioral outcomes. In phase II experiments, the authors discovered that secondary labeling in group 1 was predominantly contributed from the donor (peroneal) pool. Double-labeling counts were dramatically higher in group 2 than in group 1, suggestive of hampered regeneration from the native tibial motor neuron pool across the NIC segment in the presence of SETS. CONCLUSIONS SETS is indeed an effective strategy to enhance axonal regeneration, which is mainly contributed by the donor neuronal pool. Moreover, the presence of a distal SETS coaptation appears to negatively influence neuronal regeneration across the NIC segment. The clinical significance is that SETS should only employ synergistic donors, as the use of antagonistic donors can downgrade recovery.
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Retrograde labeling of regenerating motor and sensory neurons using silicone caps. J Neurosci Methods 2016; 259:122-128. [DOI: 10.1016/j.jneumeth.2015.11.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 11/12/2015] [Accepted: 11/23/2015] [Indexed: 02/04/2023]
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Yu YL, Li HY, Zhang PX, Yin XF, Han N, Kou YH, Jiang BG. Comparison of commonly used retrograde tracers in rat spinal motor neurons. Neural Regen Res 2015; 10:1700-5. [PMID: 26692873 PMCID: PMC4660769 DOI: 10.4103/1673-5374.167772] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The purpose of this study was to investigate the effect of four fluorescent dyes, True Blue (TB), Fluoro-Gold (FG), Fluoro-Ruby (FR), and 1,1’-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (DiI), in retrograde tracing of rat spinal motor neurons. We transected the muscle branch of the rat femoral nerve and applied each tracer to the proximal stump in single labeling experiments, or combinations of tracers (FG-DiI and TB-DiI) in double labeling experiments. In the single labeling experiments, significantly fewer labeled motor neurons were observed after FR labeling than after TB, FG, or DiI, 3 days after tracer application. By 1 week, there were no significant differences in the number of labeled neurons between the four groups. In the double-labeling experiment, the number of double-labeled neurons in the FG-DiI group was not significantly different from that in the TB-DiI group 1 week after tracer application. Our findings indicate that TB, FG, and DiI have similar labeling efficacies in the retrograde labeling of spinal motor neurons in the rat femoral nerve when used alone. Furthermore, combinations of DiI and TB or FG are similarly effective. Therefore, of the dyes studied, TB, FG and DiI, and combinations of DiI with TB or FG, are the most suitable for retrograde labeling studies of motor neurons in the rat femoral nerve.
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Affiliation(s)
- You-Lai Yu
- Department of Trauma and Orthopedics, Peking University People's Hospital, Beijing, China
| | - Hai-Yan Li
- Department of Gastroenterology, Weifang People's Hospital, Weifang, Shandong Province, China
| | - Pei-Xun Zhang
- Department of Trauma and Orthopedics, Peking University People's Hospital, Beijing, China
| | - Xiao-Feng Yin
- Department of Trauma and Orthopedics, Peking University People's Hospital, Beijing, China
| | - Na Han
- Department of Trauma and Orthopedics, Peking University People's Hospital, Beijing, China
| | - Yu-Hui Kou
- 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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Hu W, Liu D, Zhang Y, Shen Z, Gu T, Gu X, Gu J. Neurological function following intra-neural injection of fluorescent neuronal tracers in rats. Neural Regen Res 2014; 8:1253-61. [PMID: 25206419 PMCID: PMC4107650 DOI: 10.3969/j.issn.1673-5374.2013.14.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 04/22/2013] [Indexed: 12/18/2022] Open
Abstract
Fluorescent neuronal tracers should not be toxic to the nervous system when used in long-term labeling. Previous studies have addressed tracer toxicity, but whether tracers injected into an intact nerve result in functional impairment remains to be elucidated. In the present study, we examined the functions of motor, sensory and autonomic nerves following the application of 5% Fluoro-Gold, 4% True Blue and 10% Fluoro-Ruby (5 μL) to rat tibial nerves via pressure injection. A set of evaluation methods including walking track analysis, plantar test and laser Doppler perfusion imaging was used to determine the action of the fluorescent neuronal tracers. Additionally, nerve pathology and ratio of muscle wet weight were also observed. Results showed that injection of Fluoro-Gold significantly resulted in loss of motor nerve function, lower plantar sensibility, increasing blood flow volume and higher neurogenic vasodilatation. Myelinated nerve fiber degeneration, unclear boundaries in nerve fibers and high retrograde labeling efficacy were observed in the Fluoro-Gold group. The True Blue group also showed obvious neurogenic vasodilatation, but less severe loss of motor function and degeneration, and fewer labeled motor neurons were found compared with the Fluoro-Gold group. No anomalies of motor and sensory nerve function and no myelinated nerve fiber degeneration were observed in the Fluoro-Ruby group. Experimental findings indicate that Fluoro-Gold tracing could lead to significant functional impairment of motor, sensory and autonomic nerves, while functional impairment was less severe following True Blue tracing. Fluoro-Ruby injection appears to have no effect on neurological function.
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Affiliation(s)
- Wen Hu
- School of Biology and Basic Medical Sciences, Soochow University, Suzhou 215123, Jiangsu Province, China ; Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong 226001, Jiangsu Province, China
| | - Dan Liu
- Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong 226001, Jiangsu Province, China ; Department of Hand Surgery, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
| | - Yanping Zhang
- Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong 226001, Jiangsu Province, China ; Department of Hand Surgery, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
| | - Zhongyi Shen
- Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong 226001, Jiangsu Province, China ; School of Medicine, Nantong University, Nantong 226001, Jiangsu Province, China
| | - Tianwen Gu
- Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong 226001, Jiangsu Province, China ; School of Medicine, Nantong University, Nantong 226001, Jiangsu Province, China
| | - Xiaosong Gu
- School of Biology and Basic Medical Sciences, Soochow University, Suzhou 215123, Jiangsu Province, China ; Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong 226001, Jiangsu Province, China
| | - Jianhui Gu
- Department of Hand Surgery, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
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Hernández-Morato I, Berdugo-Vega G, Sañudo JR, Mchanwell S, Vázquez T, Valderrama-Canales FJ, Pascual-Font A. Somatotopic Changes in the Nucleus Ambiguus After Section and Regeneration of the Recurrent Laryngeal Nerve of the Rat. Anat Rec (Hoboken) 2014; 297:955-63. [DOI: 10.1002/ar.22877] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 12/10/2013] [Accepted: 12/18/2013] [Indexed: 11/06/2022]
Affiliation(s)
- Ignacio Hernández-Morato
- Department of Human Anatomy and Embryology I; School of Medicine, Complutense University of Madrid; Madrid Spain
| | - Gabriel Berdugo-Vega
- Department of Human Anatomy and Embryology I; School of Medicine, Complutense University of Madrid; Madrid Spain
| | - Jose R. Sañudo
- Department of Human Anatomy and Embryology I; School of Medicine, Complutense University of Madrid; Madrid Spain
| | - Stephen Mchanwell
- School of Medical Sciences Education Development; Newcastle University; Newcastle, NE2 4BW UK
| | - Teresa Vázquez
- Department of Human Anatomy and Embryology I; School of Medicine, Complutense University of Madrid; Madrid Spain
| | | | - Arán Pascual-Font
- Department of Human Anatomy and Embryology I; School of Medicine, Complutense University of Madrid; Madrid Spain
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Kim J, Han SJ, Shin DH, Lee WS, Choi JY. Subthreshold continuous electrical stimulation facilitates functional recovery of facial nerve after crush injury in rabbit. Muscle Nerve 2011; 43:251-8. [PMID: 21254091 DOI: 10.1002/mus.21840] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We sought to determine whether electrical stimulation (ES) with subthreshold, continuous, low-frequency impulses is a viable clinical method for improving functional recovery after facial nerve crush injury. In 10 rabbits, bilateral crush injuries were made on the facial nerve by compression for 30 s with mosquito forceps, causing complete facial paralysis. Subthreshold continuous direct current ES with 20-Hz square-wave pulses was applied to the proximal stump on one side for 4 weeks. Vibrissae movement returned significantly earlier on the ES side, with a less variable recovery time. Electrophysiologically, the stimulated side had a significantly shorter latency, longer duration, and faster conduction velocity. Light and transmission electron microscopy revealed that the electrical stimulation also markedly decreased Wallerian degeneration. The average numbers of fluorescent, double-labeled nerve cells were significantly different between the ES and non-ES sides. This study shows that subthreshold, continuous, low-frequency ES immediately after a crush injury of the facial nerve results in earlier recovery of facial function and shorter overall recovery time.
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Affiliation(s)
- Jin Kim
- Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul 120-752, Korea
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Gu S, Shen Y, Xu W, Xu L, Li X, Zhou G, Gu Y, Xu J. Application of fetal neural stem cells transplantation in delaying denervated muscle atrophy in rats with peripheral nerve injury. Microsurgery 2010; 30:266-74. [PMID: 19967766 DOI: 10.1002/micr.20722] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Injury to peripheral nerves always results in progressive skeletal muscle atrophy and poor functional recovery. Previous studies have demonstrated that transplanting neural stem cells (NSCs) into peripheral nerve can differentiate into neurons and delay muscle atrophy. However, the mechanism was not very clear. In this study, we transplanted the fetal NSCs to the injured nerve and examined new formed neuromuscular junctions (NMJs) in the denervated muscle and arrest of muscle atrophy. In our study, two pregnant Fischer rats were used to harvest fetal NSCs, 70 rats were randomly divided into NSC-transplanted and control groups, five rats without surgery were used as the normal control. A volume of 5 microl culture media with or without fetal NSCs (5 x 10(6)) were transplanted into distal tibial nerve stump after the nerve was transected in two groups, respectively. Three, five, and seven months after denervation, the dry weight of gastrocnemius muscle was found significant heavier, and the fiber area was more retained in NSC-transplanted group comparing to the control group (P < 0.05). Neurons were found in the distal tibial nerves even 7 months after fetal NSCs transplantation. Newly formed NMJs were detected by immunohistochemistry. In addition, the results of electrophysiological analysis and retrograde tracing manifested that the neural pathway between muscle and differentiated neurons was integrity. In conclusions, our study demonstrated that fetal NSCs transplanted into peripheral nerves could differentiate into neurons and form functional NMJs with denervated muscle, which may be beneficial for the treatment of muscle atrophy after peripheral nerve injury.
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Affiliation(s)
- Shihui Gu
- Department of Hand Surgery, Huashan Hospital, Fudan University, Shanghai, China
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Thakor D, Spigelman I, Tabata Y, Nishimura I. Subcutaneous peripheral injection of cationized gelatin/DNA polyplexes as a platform for non-viral gene transfer to sensory neurons. Mol Ther 2007; 15:2124-31. [PMID: 17622241 DOI: 10.1038/sj.mt.6300256] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Selective modulation of sensory neuron gene expression could have numerous applications for the peripheral nervous system. Here, we report that subcutaneous peripheral injection of plasmid DNA complexed with a non-viral cationized gelatin (CG) vector led to transgene expression in rat lumbar dorsal root ganglia (DRGs). CG/DNA polyplexes appeared to undergo rapid retrograde transport through sciatic and spinal nerves, with reporter gene messenger RNA (mRNA) expression detectable in L4 and L5 DRGs within 60 hours. Maximum transgene expression was observed for polyplexes formed at 7.5:1 CG-to-DNA weight ratio under salt-free conditions, which generated 615 +/- 112 nm nanoparticles with zeta-potential of 9.4 +/- 0.19 mV. Six days after injection of the CG/DNA polypex, reporter gene protein immunofluorescence was observed in 1,164 +/- 176 DRG neurons, representing an estimated transfection rate of 47% of targeted neurons. Reporter gene expression was not detected in heart, lung, or liver tissues, suggesting a lack of systemic uptake. Measurements of tactile sensitivity indicate that CG/DNA injection did not cause behavioral toxicity. The injection platform was further used for plasmid-driven short hairpin RNA-mediated suppression of glyceraldehyde-3-phosphate dehydrogenase. This non-invasive gene delivery system could be used for the mechanistic study and targeted molecular evaluation of peripheral nervous system pathologies such as neuropathic pain.
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Affiliation(s)
- Devang Thakor
- Jane and Jerry Weintraub Center for Reconstructive Biotechnology, Division of Advanced Prosthodontics, Biomaterials, and Hospital Dentistry, School of Dentistry, University of California, Los Angeles, California 90095, USA
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Tomita K, Kubo T, Matsuda K, Hattori R, Fujiwara T, Yano K, Hosokawa K. Effect of conduit repair on aberrant motor axon growth within the nerve graft in rats. Microsurgery 2007; 27:500-9. [PMID: 17596896 DOI: 10.1002/micr.20394] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
After peripheral nerve injury, minimizing axonal misdirection has been a matter of importance to obtain good functional outcomes. In general, it becomes more challenging as the nerve defect length is longer. As previous works suggested that a conduit repair leaving a short gap could induce some target-specific reinnervation, we expected that a distally placed conduit combined with nerve graft would enhance the specificity of reinnervation, especially in dealing with a long gap. To test this, a 14-mm-long gap was created in the rat sciatic nerves and repaired with either 1) whole nerve graft (WG), 2) interfascicular nerve grafts (FG), or 3) whole nerve graft combined with distally placed silicone tube leaving a 5-mm gap (TUBG). At the end of follow up, the extent of target specific reinnervation (measurement of the compound muscle action potentials evoked by stimulation of the sciatic nerve and its tibial and common peroneal fascicles) and the accuracy of motoneuronal projection (sequential retrograde labeling of the common peroneal motor pool) were assessed. Both assessments revealed that groups FG and TUBG had a similar selectivity, which was significantly higher than in group WG. Consistent with these results, the functional recovery as assessed by walking track analysis showed no significant difference between groups FG and TUBG, whereas those were significantly superior to group WG. In contrast, histomorphometric assessment of the regenerating axons and wet muscle weight showed no significant difference among the three groups. In conclusion, conduit repair would have some effects on reducing motor axonal misdirection, and it might be more effective when used in the management of a large defect in combination with nerve graft.
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Affiliation(s)
- Koichi Tomita
- Department of Plastic Surgery, Osaka University Graduate School of Medicine, Osaka, Japan.
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