1
|
Gu X, Rahman FS, Bendale G, Tran B, Miyata JF, Hernandez A, Anand S, Romero-Ortega MI. Pleiotrophin-Neuregulin1 promote axon regeneration and sorting in conduit repair of critical nerve gap injuries. RESEARCH SQUARE 2023:rs.3.rs-3429258. [PMID: 37986821 PMCID: PMC10659554 DOI: 10.21203/rs.3.rs-3429258/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Significant challenges remain in the treatment of critical nerve gap injuries using artificial nerve conduits. We previously reported successful axon regeneration across a 40 mm nerve gap using a biosynthetic nerve implant (BNI) with multi-luminal synergistic growth factor release. However, axon sorting, remyelination, and functional recovery were limited. Neuregulin1 (NRG1) plays a significant role in regulating the proliferation and differentiation of Schwann cells (SCs) during development and after injury. We hypothesize that the release of NRG1 type III combined with pleiotrophin (PTN) in the BNI will enhance axon growth, remyelination, and function of regenerated nerves across a critical gap. A rabbit 40 mm peroneal gap injury model was used to investigate the therapeutic efficacy of BNIs containing either NRG1, PTN, or PTN+NRG1 growth factor release. We found that NRG1 treatment doubled the number of regenerated axons (1276±895) compared to empty controls (633±666) and PTN tripled this number (2270±989). NRG1 also significantly increased the number of SOX10+ Schwann cells in mid-conduit (20.42%±11.78%) and reduced the number of abnormal Remak axon bundles. The combination of PTN+NRG1 increased axon diameter (1.70±1.06) vs control (1.21±0.77) (p<0.01), with 15.35% of axons above 3 μm, comparable to autograft. However, the total number of remyelinated axons was not increased by the added NRG1 release, which correlated with absence of axonal NRG1 type III expression in the regenerated axons. Electrophysiological evaluation showed higher muscle force recruitment (23.8±16.0 mN vs 17.4±1.4 mN) and maximum evoked compound motor action potential (353 μV vs 37 μV) in PTN-NRG1 group versus control, which correlated with the improvement in the toe spread recovery observed in PTN-NRG1 treated animals (0.64±0.02) vs control (0.50±0.01). These results revealed the need of a combination of pro-regenerative and remyelinating growth factor combination therapy for the repair of critical nerve gaps.
Collapse
Affiliation(s)
- Xingjian Gu
- Department of Biomedical Engineering, University of Houston, Houston TX 77204
| | - Farial S. Rahman
- Department of Biomedical Engineering, University of Houston, Houston TX 77204
| | - G Bendale
- Department of Biomedical Engineering, University of Houston, Houston TX 77204
| | - B Tran
- Department of Biomedical Engineering, University of Houston, Houston TX 77204
| | - JF Miyata
- Department of Biomedical Engineering, University of Houston, Houston TX 77204
| | - A Hernandez
- Department of Biomedical Engineering, University of Houston, Houston TX 77204
| | - S Anand
- Department of Biomedical Engineering, University of Houston, Houston TX 77204
| | | |
Collapse
|
2
|
Chi S, Li S, Cao G, Guo J, Han Y, Zhou Y, Zhang X, Li Y, Luo Z, Li X, Rong L, Zhang M, Li L, Tang S. The interplay of common genetic variants NRG1 rs2439302 and RET rs2435357 increases the risk of developing Hirschsprung's disease. Front Cell Dev Biol 2023; 11:1184799. [PMID: 37484916 PMCID: PMC10361661 DOI: 10.3389/fcell.2023.1184799] [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: 03/12/2023] [Accepted: 06/14/2023] [Indexed: 07/25/2023] Open
Abstract
Introduction: As a congenital and genetically related disease, many single nucleotide polymorphisms (SNPs) have been reported to be associated with the risk of HSCR. Our previous research showed that SNP rs2439302 (NRG1) interacted with rs2435357 (RET) to increase the risk of HSCR development. However, the underlying molecular mechanism is still not well understood. Methods: SNP rs2439302 (NRG1) and rs2435357 (RET) were genotyped in 470 HSCR cases. The expression of NRG1 and RET was investigated in the colon of HSCR patients. Knockdown of the NRG1 and RET homologs was performed in zebrafish to investigate their synergistic effect on ENS development. The effect of SNP rs2439302 and rs2435357 polymorphism on neuron proliferation, migration, and differentiation were investigated in SHSY-5Y cells and IPSCs. Results: Significant downregulation of NRG1 and RET expression was noticed in the aganglionic segment of HSCR patients and SHSY-5Y cells with rs2439302 GG/rs2435357 TT genotype. NRG1 and RET double mutants caused the most severe reduction in enteric neuron numbers than NRG1 single mutant or RET single mutant in the hindgut of zebrafish. SHSY-5Y cells and IPSCs with rs2439302 GG/rs2435357 TT genotype exhibited a decreased proliferative, migration, and differentiative capacity. CTCF showed a considerably higher binding ability to SNP rs2439302 CC than GG. NRG1 reduction caused a further decrease in SOX10 expression via the PI3K/Akt pathway, which regulates RET expression by directly binding to rs2435357. Discussion: SNP rs2439302 (NRG1) GG increases the risk of developing HSCR by affecting the binding of transcription factor CTCF and interacting with rs2435357 (RET) to regulate RET expression via the PI3K/Akt/SOX10 pathway.
Collapse
Affiliation(s)
- Shuiqing Chi
- Department of Pediatric Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Shuai Li
- Department of Pediatric Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Guoqing Cao
- Department of Pediatric Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jialing Guo
- Department of Pediatric Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yunqiao Han
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Yun Zhou
- Department of Pediatric Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xi Zhang
- Department of Pediatric Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yibo Li
- Department of Pediatric Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhibin Luo
- Department of Pediatric Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiangyang Li
- Department of Pediatric Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Liying Rong
- Department of Pediatric Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Mengxin Zhang
- Department of Pediatric Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Linglu Li
- China Zebrafish Resource Center, National Aquatic Biological Resource Center, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Shaotao Tang
- Department of Pediatric Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| |
Collapse
|
3
|
Negro S, Pirazzini M, Rigoni M. Models and methods to study Schwann cells. J Anat 2022; 241:1235-1258. [PMID: 34988978 PMCID: PMC9558160 DOI: 10.1111/joa.13606] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 11/26/2021] [Accepted: 11/29/2021] [Indexed: 12/22/2022] Open
Abstract
Schwann cells (SCs) are fundamental components of the peripheral nervous system (PNS) of all vertebrates and play essential roles in development, maintenance, function, and regeneration of peripheral nerves. There are distinct populations of SCs including: (1) myelinating SCs that ensheath axons by a specialized plasma membrane, called myelin, which enhances the conduction of electric impulses; (2) non-myelinating SCs, including Remak SCs, which wrap bundles of multiple axons of small caliber, and perysinaptic SCs (PSCs), associated with motor axon terminals at the neuromuscular junction (NMJ). All types of SCs contribute to PNS regeneration through striking morphological and functional changes in response to nerve injury, are affected in peripheral neuropathies and show abnormalities and a diminished plasticity during aging. Therefore, methodological approaches to study and manipulate SCs in physiological and pathophysiological conditions are crucial to expand the present knowledge on SC biology and to devise new therapeutic strategies to counteract neurodegenerative conditions and age-derived denervation. We present here an updated overview of traditional and emerging methodologies for the study of SCs for scientists approaching this research field.
Collapse
Affiliation(s)
- Samuele Negro
- Department of Biomedical SciencesUniversity of PaduaPaduaItaly
| | - Marco Pirazzini
- Department of Biomedical SciencesUniversity of PaduaPaduaItaly
- CIR‐MyoCentro Interdipartimentale di Ricerca di MiologiaUniversity of PaduaPadovaItaly
| | - Michela Rigoni
- Department of Biomedical SciencesUniversity of PaduaPaduaItaly
- CIR‐MyoCentro Interdipartimentale di Ricerca di MiologiaUniversity of PaduaPadovaItaly
| |
Collapse
|
4
|
Abstract
BACKGROUND Acellular nerve allograft (ANA) occupies an increasingly prominent role in the treatment of peripheral nerve reconstruction. There is demonstrable efficacy; however, some grafts fail to support axonal regrowth and the reasons for this are unclear. This study examines the ANA experience in a specialized peripheral nerve surgery department to discuss the clinical and histological findings in failed cases. METHOD Failed ANA grafts were identified from a prospective database using Medical Research Council Classification (MRCC) S3 and M3 as thresholds for success. Cases in which ANA grafting was indicated for nerve related pain and dysesthesia but where no subjective improvement in symptoms occurred were also included. Patients requiring revision surgery after ANA grafting were also considered failures. Cases were then examined in conjunction with a literature review to identify possible mechanisms of failure, including detailed histological analysis in 2 cases. RESULTS Eight failed procedures were identified from a database of 99 separate allograft records on 74 patients. This included procedures for 2 tibial nerves, 2 superficial radial nerves, 2 median nerves, 1 digital nerve and a lateral cord brachial plexus injury (male/female, 5:3; age range, 24-54 years). Allograft length range 25 to 120 mm. One postoperative infection was identified. Histological findings in 2 cases included adequate vascularization of allograft material without subsequent axonal regeneration, a reduction of large myelinated fibers proximal to a tibial nerve allograft in the setting of a chronic injury, and a preference for small rather than large fiber regeneration. CONCLUSIONS This article reports instances of ANA graft failure in a variety of contexts, for which the primary reasons for failure remain unclear. The etiology is likely to be multifactorial with both patient, graft and surgeon factors contributing to failure. Further clinical and histological analysis of ANA failures will improve our understanding of the mechanisms of graft failure.
Collapse
Affiliation(s)
- Calum Thomson
- From the Department of Peripheral Nerve Surgery, Queen Elizabeth Hospital
| | | | - Ute Pohl
- Department of Cellular Pathology
| | - Dominic M Power
- The Birmingham Peripheral Nerve Injury Service, Queen Elizabeth Hospital, Birmingham, United Kingdom
| |
Collapse
|
5
|
Dong X, Wu P, Yan L, Liu K, Wei W, Cheng Q, Liang X, Chen Y, Dai H. Oriented nanofibrous P(MMD-co-LA)/Deferoxamine nerve scaffold facilitates peripheral nerve regeneration by regulating macrophage phenotype and revascularization. Biomaterials 2021; 280:121288. [PMID: 34894585 DOI: 10.1016/j.biomaterials.2021.121288] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 11/12/2021] [Accepted: 11/25/2021] [Indexed: 12/14/2022]
Abstract
Delayed injured nerve regeneration remains a clinical problem, partly ascribing to the lack of regulation of regenerative microenvironment, topographical cues, and blood nourishment. Functional electrospun conduits have been established as an efficacious strategy to facilitate nerve regeneration by providing structural guidance, regulating the regenerative immune microenvironment, and improving vascular regeneration. However, the synthetic polymers conventionally used to fabricate electrospinning scaffolds, such as poly(L-lactic acid), poly(glycolic acid), and poly(lactic-co-glycolic acid), can cause aseptic inflammation due to acidic degradation products. Therefore, a poly[3(S)-methyl-morpholine-2,5-dione-co-lactic] [P(MMD-co-LA)] containing alanine units with good mechanical properties and reduced acid degradation products, was obtained by melt ring-opening polymerization (ROP). Here, we aimed to explore the effect of oriented nanofiber/Deferoxamine (DFO, a hydrophilic angiogenic drug) scaffold in the rapid construction of a favorable regenerative microenvironment, including cell bridge, polarized vascular system, and immune microenvironment. In vitro studies have shown that the scaffold can sustainably release DFO, which accelerates the migration and tube formation of human umbilical vein endothelial cells (HUVECs), as well as the expression of genes related to angiogenesis. The physical clues provided by the arranged nanofibers can regulate the polarization of macrophages and reduce the expression of inflammatory factors. Furthermore, the in vivo results demonstrated a higher M2 polarization level of the oriented nanofibrous scaffold treatment group with reducedinflammation reaction in the injured nerve. Moreover, the in-situ release of DFO up-regulated the expression of HIF1-α and SDF-1α genes, as well as the expression of HIF1-α's target gene VEGF, further promoting revascularization and enhancing nerve regeneration at the defect site. The obtained results provide essential insights on accelerating the creation of the nerve regeneration microenvironment by combining the physiological processes of nerve regeneration with topographical cues and chemical signal induction.
Collapse
Affiliation(s)
- Xianzhen Dong
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Biomedical Materials and Engineering Research Center of Hubei Province, Wuhan University of Technology, Wuhan, 430070, China
| | - Ping Wu
- Department of Biomedical Engineering and Hubei Province Key Laboratory of Allergy and Immune-Related Diseases, School of Basic Medical Sciences, Wuhan University, Wuhan, 430071, China
| | - Lesan Yan
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Biomedical Materials and Engineering Research Center of Hubei Province, Wuhan University of Technology, Wuhan, 430070, China
| | - Kun Liu
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Biomedical Materials and Engineering Research Center of Hubei Province, Wuhan University of Technology, Wuhan, 430070, China
| | - Wenying Wei
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Biomedical Materials and Engineering Research Center of Hubei Province, Wuhan University of Technology, Wuhan, 430070, China
| | - Qiang Cheng
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Biomedical Materials and Engineering Research Center of Hubei Province, Wuhan University of Technology, Wuhan, 430070, China
| | - Xinyue Liang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Biomedical Materials and Engineering Research Center of Hubei Province, Wuhan University of Technology, Wuhan, 430070, China
| | - Yun Chen
- Department of Biomedical Engineering and Hubei Province Key Laboratory of Allergy and Immune-Related Diseases, School of Basic Medical Sciences, Wuhan University, Wuhan, 430071, China.
| | - Honglian Dai
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Biomedical Materials and Engineering Research Center of Hubei Province, Wuhan University of Technology, Wuhan, 430070, China; Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory, Xianhu Hydrogen Valley, Foshan, 528200, China.
| |
Collapse
|
6
|
Sohn EJ, Nam YK. The Transcription Factor TFCP2L1 is Associated with Myelination via miR708-5p Regulation in the Peripheral Nerve System. Neurochem Res 2021; 47:434-445. [PMID: 34581937 DOI: 10.1007/s11064-021-03457-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 08/25/2021] [Accepted: 09/22/2021] [Indexed: 11/25/2022]
Abstract
MicroRNAs (miRNAs) have been implicated in nerve injury and demyelination; however, their functions in peripheral nerves remain unclear. To determine the potential functions of miRNAs, an miRNA array was carried out. Here, miRNA array analysis of neuregulin-treated Schwann cells revealed 18 upregulated (> 2-fold) and 13 downregulated (> 2-fold) miRNAs. After sciatic nerve injury, miR708-5p was highly expressed in neuregulin-treated Schwann cells, whereas it was downregulated during postnatal development. A predicted functional interaction was found between miR708-5p and transcription factor CP2-like protein 1 (TFCP2L1) using a bioinformatics tool. This finding suggested that miR708-5p may regulate TFCP2L1. During sciatic nerve development, TFCP2L1 was upregulated on postnatal days 1 and 4, while it was downregulated after nerve axotomy and crush injury. Notably, TFCP2L1 was upregulated in cAMP-treated Schwann cells. We also found that activity of the myelin protein zero promoter was downregulated in TFCP2L1 siRNA-treated Schwann cells, whereas it was upregulated in TFCP2L1-overexpressing cells. Immunofluorescence analysis showed that TFCP2L1 was localized in Schwann cells. In addition, miR708-5p overexpression promoted migration of Schwann cells, while miR-708-5p inhibitor inhibited migration. miR708-5p inhibitor also blocked the migration of TFCP2L1 siRNA-treated Schwann cells. These findings indicate the functions of miR708-5p in TFCP2L1 regulation in the peripheral nervous system occur via regulation of Schwann cell migration.
Collapse
Affiliation(s)
- Eun Jung Sohn
- Department of Convergence Medical Sciences, School of Medicine, Pusan National University, Pusan National University, Yangsan, South Korea.
| | - Yun Kyung Nam
- Department of Molecular Neuroscience, College of Medicine, Dong-A University, Busan, South Korea
| |
Collapse
|
7
|
Malavasi EL, Ghosh A, Booth DG, Zagnoni M, Sherman DL, Brophy PJ. Dynamic early clusters of nodal proteins contribute to node of Ranvier assembly during myelination of peripheral neurons. eLife 2021; 10:68089. [PMID: 34240706 PMCID: PMC8289411 DOI: 10.7554/elife.68089] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 07/07/2021] [Indexed: 12/31/2022] Open
Abstract
Voltage-gated sodium channels cluster in macromolecular complexes at nodes of Ranvier to promote rapid nerve impulse conduction in vertebrate nerves. Node assembly in peripheral nerves is thought to be initiated at heminodes at the extremities of myelinating Schwann cells, and fusion of heminodes results in the establishment of nodes. Here we show that assembly of 'early clusters' of nodal proteins in the murine axonal membrane precedes heminode formation. The neurofascin (Nfasc) proteins are essential for node assembly, and the formation of early clusters also requires neuronal Nfasc. Early clusters are mobile and their proteins are dynamically recruited by lateral diffusion. They can undergo fusion not only with each other but also with heminodes, thus contributing to the development of nodes in peripheral axons. The formation of early clusters constitutes the earliest stage in peripheral node assembly and expands the repertoire of strategies that have evolved to establish these essential structures.
Collapse
Affiliation(s)
- Elise Lv Malavasi
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Aniket Ghosh
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Daniel G Booth
- Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Michele Zagnoni
- Centre for Microsystems & Photonics, Dept. Electronic and Electrical Engineering, University of Strathclyde, Strathclyde, United Kingdom
| | - Diane L Sherman
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Peter J Brophy
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| |
Collapse
|
8
|
GFAP and desmin expression in lymphatic tissues leads to difficulties in distinguishing between glial and stromal cells. Sci Rep 2021; 11:13322. [PMID: 34172765 PMCID: PMC8233388 DOI: 10.1038/s41598-021-92364-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 06/07/2021] [Indexed: 11/12/2022] Open
Abstract
Recently, we found many immune cells including antigen presenting cells neurally hard wired in the T-cell zone of most lymphoid organs like amongst others, lymph nodes in rats, mice and humans. Single immune cells were reached by single neurites and enclosed with a dense neural meshwork. As it is well known that axons are always accompanied by glial cells, we were able to identify Schwann cells in the hilum, medullary and capsule region, like expected. Unexpected was the result, that we found oligodendrocyte-like cells in these regions, myelinating more than one axon. Likewise important was the finding, that one of the standard glial markers used, a polyclonal GFAP antibody equally bound to desmin and therefore marked nearly all stromal cells in cortical, paracortical and medullary cord regions. More detailed analysis showed that these results also appeared in many other non-lymphoid organs. Therefore, polyclonal GFAP antibodies are only conditionally usable for immunohistochemical analysis in peripheral tissues outside the central nervous system. It remains to be elucidated, if the binding of the GFAP antibody to desmin has its reason in a special desmin variant that can give stromal cells glial character.
Collapse
|
9
|
Fontenas L, Kucenas S. Spinal cord precursors utilize neural crest cell mechanisms to generate hybrid peripheral myelinating glia. eLife 2021; 10:64267. [PMID: 33554855 PMCID: PMC7886336 DOI: 10.7554/elife.64267] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 02/05/2021] [Indexed: 12/11/2022] Open
Abstract
During development, oligodendrocytes and Schwann cells myelinate central and peripheral nervous system axons, respectively, while motor exit point (MEP) glia are neural tube-derived, peripheral glia that myelinate axonal territory between these populations at MEP transition zones. From which specific neural tube precursors MEP glia are specified, and how they exit the neural tube to migrate onto peripheral motor axons, remain largely unknown. Here, using zebrafish, we found that MEP glia arise from lateral floor plate precursors and require foxd3 to delaminate and exit the spinal cord. Additionally, we show that similar to Schwann cells, MEP glial development depends on axonally derived neuregulin1. Finally, our data demonstrate that overexpressing axonal cues is sufficient to generate additional MEP glia in the spinal cord. Overall, these studies provide new insight into how a novel population of hybrid, peripheral myelinating glia are generated from neural tube precursors and migrate into the periphery.
Collapse
Affiliation(s)
- Laura Fontenas
- Department of Biology, University of Virginia, Charlottesville, United States
| | - Sarah Kucenas
- Department of Biology, University of Virginia, Charlottesville, United States
| |
Collapse
|
10
|
Zhang RC, Du WQ, Zhang JY, Yu SX, Lu FZ, Ding HM, Cheng YB, Ren C, Geng DQ. Mesenchymal stem cell treatment for peripheral nerve injury: a narrative review. Neural Regen Res 2021; 16:2170-2176. [PMID: 33818489 PMCID: PMC8354135 DOI: 10.4103/1673-5374.310941] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Peripheral nerve injuries occur as the result of sudden trauma and lead to reduced quality of life. The peripheral nervous system has an inherent capability to regenerate axons. However, peripheral nerve regeneration following injury is generally slow and incomplete that results in poor functional outcomes such as muscle atrophy. Although conventional surgical procedures for peripheral nerve injuries present many benefits, there are still several limitations including scarring, difficult accessibility to donor nerve, neuroma formation and a need to sacrifice the autologous nerve. For many years, other therapeutic approaches for peripheral nerve injuries have been explored, the most notable being the replacement of Schwann cells, the glial cells responsible for clearing out debris from the site of injury. Introducing cultured Schwann cells to the injured sites showed great benefits in promoting axonal regeneration and functional recovery. However, there are limited sources of Schwann cells for extraction and difficulties in culturing Schwann cells in vitro. Therefore, novel therapeutic avenues that offer maximum benefits for the treatment of peripheral nerve injuries should be investigated. This review focused on strategies using mesenchymal stem cells to promote peripheral nerve regeneration including exosomes of mesenchymal stem cells, nerve engineering using the nerve guidance conduits containing mesenchymal stem cells, and genetically engineered mesenchymal stem cells. We present the current progress of mesenchymal stem cell treatment of peripheral nerve injuries.
Collapse
Affiliation(s)
- Rui-Cheng Zhang
- Department of Neurology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Wen-Qi Du
- Department of Human Anatomy, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Jing-Yuan Zhang
- Department of Neurosurgery, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong Province, China
| | - Shao-Xia Yu
- Department of Neurology, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong Province, China
| | - Fang-Zhi Lu
- Department of Neurology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Hong-Mei Ding
- Department of Neurology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Yan-Bo Cheng
- Department of Neurology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Chao Ren
- Department of Neurology, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong Province, China
| | - De-Qin Geng
- Department of Neurology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| |
Collapse
|
11
|
Min Q, Parkinson DB, Dun XP. Migrating Schwann cells direct axon regeneration within the peripheral nerve bridge. Glia 2020; 69:235-254. [PMID: 32697392 DOI: 10.1002/glia.23892] [Citation(s) in RCA: 120] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 07/03/2020] [Accepted: 07/08/2020] [Indexed: 12/12/2022]
Abstract
Schwann cells within the peripheral nervous system possess a remarkable regenerative potential. Current research shows that peripheral nerve-associated Schwann cells possess the capacity to promote repair of multiple tissues including peripheral nerve gap bridging, skin wound healing, digit tip repair as well as tooth regeneration. One of the key features of the specialized repair Schwann cells is that they become highly motile. They not only migrate into the area of damaged tissue and become a key component of regenerating tissue but also secrete signaling molecules to attract macrophages, support neuronal survival, promote axonal regrowth, activate local mesenchymal stem cells, and interact with other cell types. Currently, the importance of migratory Schwann cells in tissue regeneration is most evident in the case of a peripheral nerve transection injury. Following nerve transection, Schwann cells from both proximal and distal nerve stumps migrate into the nerve bridge and form Schwann cell cords to guide axon regeneration. The formation of Schwann cell cords in the nerve bridge is key to successful peripheral nerve repair following transection injury. In this review, we first examine nerve bridge formation and the behavior of Schwann cell migration in the nerve bridge, and then discuss how migrating Schwann cells direct regenerating axons into the distal nerve. We also review the current understanding of signals that could activate Schwann cell migration and signals that Schwann cells utilize to direct axon regeneration. Understanding the molecular mechanism of Schwann cell migration could potentially offer new therapeutic strategies for peripheral nerve repair.
Collapse
Affiliation(s)
- Qing Min
- School of Pharmacy, Hubei University of Science and Technology, Xianning, Hubei Province, People's Republic of China
| | - David B Parkinson
- Peninsula Medical School, Faculty of Health, Plymouth University, Plymouth, Devon, UK
| | - Xin-Peng Dun
- School of Pharmacy, Hubei University of Science and Technology, Xianning, Hubei Province, People's Republic of China
- Peninsula Medical School, Faculty of Health, Plymouth University, Plymouth, Devon, UK
- The Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, People's Republic of China
| |
Collapse
|
12
|
Jafari M, Delaviz H, Torabi S, Mohammadi J, Gheitasi I. The Effect of Muscle Graft With Nerve Growth Factor and Laminin on Sciatic Nerve Repair in Rats. Basic Clin Neurosci 2020; 10:333-344. [PMID: 32231770 PMCID: PMC7101516 DOI: 10.32598/bcn.9.10.145] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 04/29/2017] [Accepted: 03/03/2018] [Indexed: 11/21/2022] Open
Abstract
Introduction: Peripheral nerve injury is one of the most common damages that lead to physical disability. Considering the similarity between the coatings of skeletal muscles and nerve fibers, we conducted this research to determine the effect of muscle graft with Nerve Growth Factor (NGF) and Laminin (L) on nerve repair. Methods: We cut a 10-mm length of the sciatic nerve from 42 female Wistar rats (Weight: 200±250 g) and equally divided the rats into three groups. In the muscle graft+NGF+laminin group, the degenerated skeletal muscle was sutured with proximal and distal ends of the transected sciatic nerve. Then, NGF (100 ng) and laminin (1.28 mg/mL) were injected into the muscle graft. In the muscle graft group, normal saline was injected into the muscle graft. In the control group, 10 mm of the sciatic nerve was removed without any treatment. Functional recovery was assessed based on Sciatic Functional Index (SFI). Also, tracing motor neurons and histological studies were performed to evaluate nerve repair. The obtained data were analyzed by ANOVA test. Results: The Mean±SD SFI value significantly increased in the muscle graft+NGF+laminin (−76.6±2.9) and muscle graft (−82.1±3.5) groups 60 days after the injury compared to the control group. The Mean±SD number of labeled motor neurons significantly increased in the muscle graft+NGF+laminin (78.6±3.1) and muscle graft (61.3±6.1) groups compared to the control group (P<0.001). The mean number of myelinated axons in the distal segments of the muscle graft+NGF+laminin increased significantly compared to the muscle graft group. Conclusion: These findings suggest that muscle graft followed by NGF and laminin administration have therapeutic effects on nerve repair.
Collapse
Affiliation(s)
- Mehrzad Jafari
- Cellular and Molecular Research Center, Yasuj University of Medical Sciences, Yasuj, Iran
| | - Hamdollah Delaviz
- Cellular and Molecular Research Center, Yasuj University of Medical Sciences, Yasuj, Iran
| | - Somayeh Torabi
- Cellular and Molecular Research Center, Yasuj University of Medical Sciences, Yasuj, Iran
| | - Jamshid Mohammadi
- Herbal Medicine Research Center, Yasuj University of Medical Sciences, Yasuj, Iran
| | - Izadpanah Gheitasi
- Herbal Medicine Research Center, Yasuj University of Medical Sciences, Yasuj, Iran
| |
Collapse
|
13
|
Adhipandito CF, Ludji DPKS, Aprilianto E, Jenie RI, Al-Najjar B, Hariono M. Matrix metalloproteinase9 as the protein target in anti-breast cancer drug discovery: an approach by targeting hemopexin domain. FUTURE JOURNAL OF PHARMACEUTICAL SCIENCES 2019. [DOI: 10.1186/s43094-019-0001-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
|
14
|
Kang WB, Chen YJ, Lu DY, Yan JZ. Folic acid contributes to peripheral nerve injury repair by promoting Schwann cell proliferation, migration, and secretion of nerve growth factor. Neural Regen Res 2019; 14:132-139. [PMID: 30531087 PMCID: PMC6263007 DOI: 10.4103/1673-5374.243718] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
After peripheral nerve injury, intraperitoneal injection of folic acid improves axon quantity, increases axon density and improves electromyography results. However, the mechanisms for this remain unclear. This study explored whether folic acid promotes peripheral nerve injury repair by affecting Schwann cell function. Primary Schwann cells were obtained from rats by in vitro separation and culture. Cell proliferation, assayed using the Cell Counting Kit-8 assay, was higher in cells cultured for 72 hours with 100 mg/L folic acid compared with the control group. Cell proliferation was also higher in the 50, 100, 150, and 200 mg/L folic acid groups compared with the control group after culture for 96 hours. Proliferation was markedly higher in the 100 mg/L folic acid group compared with the 50 mg/L folic acid group and the 40 ng/L nerve growth factor group. In Transwell assays, the number of migrated Schwann cells dramatically increased after culture with 100 and 150 mg/L folic acid compared with the control group. In nerve growth factor enzyme-linked immunosorbent assays, treatment of Schwann cell cultures with 50, 100, and 150 mg/L folic acid increased levels of nerve growth factor in the culture medium compared with the control group at 3 days. The nerve growth factor concentration of Schwann cell cultures treated with 100 mg/L folic acid group was remarkably higher than that in the 50 and 150 mg/L folic acid groups at 3 days. Nerve growth factor concentration in the 10, 50, and 100 mg/L folic acid groups was higher than that in the control group at 7 days. The nerve growth factor concentration in the 50 mg/L folic acid group was remarkably higher than that in the 10 and 100 mg/L folic acid groups at 7 days. In vivo, 80 μg/kg folic acid was intraperitoneally administrated for 7 consecutive days after sciatic nerve injury. Immunohistochemical staining showed that the number of Schwann cells in the folic acid group was greater than that in the control group. We suggest that folic acid may play a role in improving the repair of peripheral nerve injury by promoting the proliferation and migration of Schwann cells and the secretion of nerve growth factors.
Collapse
Affiliation(s)
- Wei-Bo Kang
- Department of Orthopedic Surgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Yong-Jie Chen
- Department of Orthopedic Surgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Du-Yi Lu
- Department of Orthopedic Surgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Jia-Zhi Yan
- Department of Orthopedic Surgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| |
Collapse
|
15
|
Wang P, Yang M, Jiang L, Wu YJ. A fungicide miconazole ameliorates tri-o-cresyl phosphate-induced demyelination through inhibition of ErbB/Akt pathway. Neuropharmacology 2018; 148:31-39. [PMID: 30553827 DOI: 10.1016/j.neuropharm.2018.12.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 11/21/2018] [Accepted: 12/12/2018] [Indexed: 12/21/2022]
Abstract
Organophosphorus compound (OP)-induced delayed neuropathy (OPIDN) is characterized by distal axonal degeneration and demyelination of the central and peripheral axons, which leads to progressive muscle weakness, ataxia and paralysis in several days after OP intoxication. This study aimed to investigate the possible use of an imidazole fungicide miconazole as a novel therapy for OPIDN. Adult hens, the most commonly used animal models in OPIDN studies, were orally given tri-o-cresyl phosphate (TOCP). We showed that miconazole, which was administered daily to hens beginning on the 7th day after TOCP exposure, drastically ameliorated the neurotoxic symptoms and histopathological damages in spinal cord and sciatic nerves. Mechanistically, miconazole inhibited the TOCP-induced activation of ErbB/Akt signaling, and enhanced the myelin basic protein (MBP) expression. In a glial cell model sNF96.2 cells, miconazole restored the TOCP-inhibited MBP expression, and promoted cell differentiation as well as cell migration by inhibiting the activation of ErbB/Akt signaling pathway. In sum, miconazole, a synthetic imidazole fungicide, could ameliorate the symptoms and histopathological changes of OPIDN, probably by promoting glial cell differentiation and migration to enhance myelination via inhibiting the activation of ErbB/Akt. Thus, miconazole is a promising candidate therapy for the clinical treatment of OPIDN.
Collapse
Affiliation(s)
- Pan Wang
- Laboratory of Molecular Toxicology, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1-5 Beichenxilu Road, Beijing, 100101, China
| | - Min Yang
- Laboratory of Molecular Toxicology, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1-5 Beichenxilu Road, Beijing, 100101, China
| | - Lu Jiang
- Laboratory of Molecular Toxicology, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1-5 Beichenxilu Road, Beijing, 100101, China
| | - Yi-Jun Wu
- Laboratory of Molecular Toxicology, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1-5 Beichenxilu Road, Beijing, 100101, China.
| |
Collapse
|
16
|
Lau YT, Kwok LF, Tam KW, Chan YS, Shum DKY, Shea GKH. Genipin-treated chitosan nanofibers as a novel scaffold for nerve guidance channel design. Colloids Surf B Biointerfaces 2018; 162:126-134. [DOI: 10.1016/j.colsurfb.2017.11.061] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2017] [Revised: 10/30/2017] [Accepted: 11/22/2017] [Indexed: 10/18/2022]
|
17
|
Ronchi G, Cillino M, Gambarotta G, Fornasari BE, Raimondo S, Pugliese P, Tos P, Cordova A, Moschella F, Geuna S. Irreversible changes occurring in long-term denervated Schwann cells affect delayed nerve repair. J Neurosurg 2017; 127:843-856. [DOI: 10.3171/2016.9.jns16140] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVEMultiple factors may affect functional recovery after peripheral nerve injury, among them the lesion site and the interval between the injury and the surgical repair. When the nerve segment distal to the lesion site undergoes chronic degeneration, the ensuing regeneration (when allowed) is often poor. The aims of the current study were as follows: 1) to examine the expression changes of the neuregulin 1/ErbB system during long-term nerve degeneration; and 2) to investigate whether a chronically denervated distal nerve stump can sustain nerve regeneration of freshly axotomized axons.METHODSThis study used a rat surgical model of delayed nerve repair consisting of a cross suture between the chronically degenerated median nerve distal stump and the freshly axotomized ulnar proximal stump. Before the suture, a segment of long-term degenerated median nerve stump was harvested for analysis. Functional, morphological, morphometric, and biomolecular analyses were performed.RESULTSThe results showed that neuregulin 1 is highly downregulated after chronic degeneration, as well as some Schwann cell markers, demonstrating that these cells undergo atrophy, which was also confirmed by ultrastructural analysis. After delayed nerve repair, it was observed that chronic degeneration of the distal nerve stump compromises nerve regeneration in terms of functional recovery, as well as the number and size of regenerated myelinated fibers. Moreover, neuregulin 1 is still downregulated after delayed regeneration.CONCLUSIONSThe poor outcome after delayed nerve regeneration might be explained by Schwann cell impairment and the consequent ineffective support for nerve regeneration. Understanding the molecular and biological changes occurring both in the chronically degenerating nerve and in the delayed nerve repair may be useful to the development of new strategies to promote nerve regeneration. The results suggest that neuregulin 1 has an important role in Schwann cell activity after denervation, indicating that its manipulation might be a good strategy for improving outcome after delayed nerve repair.
Collapse
Affiliation(s)
- Giulia Ronchi
- 1Department of Clinical and Biological Sciences,
- 2Neuroscience Institute Cavalieri Ottolenghi, and
| | - Michele Cillino
- 3Plastic and Reconstructive Surgery, Department of Surgical, Oncological and Oral Sciences, University of Palermo, Italy
| | | | | | - Stefania Raimondo
- 1Department of Clinical and Biological Sciences,
- 2Neuroscience Institute Cavalieri Ottolenghi, and
| | - Pierfrancesco Pugliese
- 4Reconstructive Microsurgery, Centro Traumatologico Ortopedico Hospital, University of Torino; and
| | - Pierluigi Tos
- 4Reconstructive Microsurgery, Centro Traumatologico Ortopedico Hospital, University of Torino; and
| | - Adriana Cordova
- 3Plastic and Reconstructive Surgery, Department of Surgical, Oncological and Oral Sciences, University of Palermo, Italy
| | - Francesco Moschella
- 3Plastic and Reconstructive Surgery, Department of Surgical, Oncological and Oral Sciences, University of Palermo, Italy
| | - Stefano Geuna
- 1Department of Clinical and Biological Sciences,
- 2Neuroscience Institute Cavalieri Ottolenghi, and
| |
Collapse
|
18
|
Church JS, Milich LM, Lerch JK, Popovich PG, McTigue DM. E6020, a synthetic TLR4 agonist, accelerates myelin debris clearance, Schwann cell infiltration, and remyelination in the rat spinal cord. Glia 2017; 65:883-899. [PMID: 28251686 DOI: 10.1002/glia.23132] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 02/02/2017] [Accepted: 02/03/2017] [Indexed: 12/26/2022]
Abstract
Oligodendrocyte progenitor cells (OPCs) are present throughout the adult brain and spinal cord and can replace oligodendrocytes lost to injury, aging, or disease. Their differentiation, however, is inhibited by myelin debris, making clearance of this debris an important step for cellular repair following demyelination. In models of peripheral nerve injury, TLR4 activation by lipopolysaccharide (LPS) promotes macrophage phagocytosis of debris. Here we tested whether the novel synthetic TLR4 agonist E6020, a Lipid A mimetic, promotes myelin debris clearance and remyelination in spinal cord white matter following lysolecithin-induced demyelination. In vitro, E6020 induced TLR4-dependent cytokine expression (TNFα, IL1β, IL-6) and NF-κB signaling, albeit at ∼10-fold reduced potency compared to LPS. Microinjection of E6020 into the intact rat spinal cord gray/white matter border induced macrophage activation, OPC proliferation, and robust oligodendrogenesis, similar to what we described previously using an intraspinal LPS microinjection model. Finally, a single co-injection of E6020 with lysolecithin into spinal cord white matter increased axon sparing, accelerated myelin debris clearance, enhanced Schwann cell infiltration into demyelinated lesions, and increased the number of remyelinated axons. In vitro assays confirmed that direct stimulation of macrophages by E6020 stimulates myelin phagocytosis. These data implicate TLR4 signaling in promoting repair after CNS demyelination, likely by stimulating phagocytic activity of macrophages, sparing axons, recruiting myelinating cells, and promoting remyelination. This work furthers our understanding of immune-myelin interactions and identifies a novel synthetic TLR4 agonist as a potential therapeutic avenue for white matter demyelinating conditions such as spinal cord injury and multiple sclerosis.
Collapse
Affiliation(s)
- Jamie S Church
- Neuroscience Graduate Program, The Ohio State University, Columbus, Ohio, USA.,Center for Brain and Spinal Cord Repair, The Ohio State University, Columbus, Ohio, USA
| | - Lindsay M Milich
- Department of Neuroscience, The Ohio State University, Columbus, Ohio, USA
| | - Jessica K Lerch
- Center for Brain and Spinal Cord Repair, The Ohio State University, Columbus, Ohio, USA.,Department of Neuroscience, The Ohio State University, Columbus, Ohio, USA
| | - Phillip G Popovich
- Center for Brain and Spinal Cord Repair, The Ohio State University, Columbus, Ohio, USA.,Department of Neuroscience, The Ohio State University, Columbus, Ohio, USA
| | - Dana M McTigue
- Center for Brain and Spinal Cord Repair, The Ohio State University, Columbus, Ohio, USA.,Department of Neuroscience, The Ohio State University, Columbus, Ohio, USA
| |
Collapse
|
19
|
Carr L, Parkinson DB, Dun XP. Expression patterns of Slit and Robo family members in adult mouse spinal cord and peripheral nervous system. PLoS One 2017; 12:e0172736. [PMID: 28234971 PMCID: PMC5325304 DOI: 10.1371/journal.pone.0172736] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 02/08/2017] [Indexed: 11/19/2022] Open
Abstract
The secreted glycoproteins, Slit1-3, are classic axon guidance molecules that act as repulsive cues through their well characterised receptors Robo1-2 to allow precise axon pathfinding and neuronal migration. The expression patterns of Slit1-3 and Robo1-2 have been most characterized in the rodent developing nervous system and the adult brain, but little is known about their expression patterns in the adult rodent peripheral nervous system. Here, we report a detailed expression analysis of Slit1-3 and Robo1-2 in the adult mouse sciatic nerve as well as their expression in the nerve cell bodies within the ventral spinal cord (motor neurons) and dorsal root ganglion (sensory neurons). Our results show that, in the adult mouse peripheral nervous system, Slit1-3 and Robo1-2 are expressed in the cell bodies and axons of both motor and sensory neurons. While Slit1 and Robo2 are only expressed in peripheral axons and their cell bodies, Slit2, Slit3 and Robo1 are also expressed in satellite cells of the dorsal root ganglion, Schwann cells and fibroblasts of peripheral nerves. In addition to these expression patterns, we also demonstrate the expression of Robo1 in blood vessels of the peripheral nerves. Our work gives important new data on the expression patterns of Slit and Robo family members within the peripheral nervous system that may relate both to nerve homeostasis and the reaction of the peripheral nerves to injury.
Collapse
Affiliation(s)
- Lauren Carr
- Plymouth University Peninsula Schools of Medicine and Dentistry, Plymouth, Devon, United Kingdom
| | - David B. Parkinson
- Plymouth University Peninsula Schools of Medicine and Dentistry, Plymouth, Devon, United Kingdom
| | - Xin-peng Dun
- Plymouth University Peninsula Schools of Medicine and Dentistry, Plymouth, Devon, United Kingdom
- Hubei University of Science and Technology, Xian-Ning City, Hubei, China
| |
Collapse
|
20
|
Huang G, Sun Z, Wu J, Shui S, Han X, Guo D, Li T. Calreticulin Promotes Proliferation and Migration But Inhibits Apoptosis in Schwann Cells. Med Sci Monit 2016; 22:4516-4522. [PMID: 27876711 PMCID: PMC5132423 DOI: 10.12659/msm.900956] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Background Previous studies indicated that calreticulin (CRT) regulated various biological processes. This study was aimed to investigate the function of CRT in Schwann cells (SCs). Material/Methods SCs were separated from sciatic nerves of mice and were transfected with pcDNA3.1-CRT (pc-CRT), small interfering RNA targets CRT (siCRT), or their corresponding negative controls. The expression of CRT was determined by quantitative reverse transcription PCR (qRT-PCR) and Western blot analysis. Then, cell proliferation, migration, and apoptosis were measured by 3-(4, 5-dimethylhiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, modified 2-chamber migration assay, and flow cytometry, respectively. Finally, the phosphorylation levels of key kinases in the phosphatidylinositol-3-kinase (PI3K)/AKT and the extracellular signal-regulated kinase/ribosomal S6 kinase 2 (ERK/S6) pathways were detected by Western blot analysis. Results Overexpression of CRT remarkably increased viability (P<0.05, P<0.01 or P<0.001) and migration (P<0.001), but inhibited apoptosis (P<0.05). The CRT-knockdown showed the inverse impacts on viability (P<0.05 or P<0.001), migration (P<0.001), and apoptosis (P<0.001). Additionally, the phosphorylation levels of AKT (Thr308 and Ser473), ERK, and S6 were all up-regulated in CRT-overexpressed cells (P<0.001), and were down-regulated in CRT-knockdown cells (P<0.05, P<0.01 or P<0.001). Conclusions Overexpression of CRT in SCs promoted cell proliferation and migration but suppressed cell apoptosis. The PI3K/AKT and ERK/S6 pathways might be involved in the functional effects of CRT on SCs.
Collapse
Affiliation(s)
- Gui Huang
- Department of Pathology, Huaihe Hospital, Henan University, Kaifeng, Henan, China (mainland)
| | - Zhulei Sun
- Department of Pathology, Huaihe Hospital, Henan University, Kaifeng, Henan, China (mainland)
| | - Jiang Wu
- Department of Pathology, Huaihe Hospital, Henan University, Kaifeng, Henan, China (mainland)
| | - Shaofeng Shui
- Department of Interventional Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China (mainland)
| | - Xinwei Han
- Department of Interventional Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China (mainland)
| | - Dong Guo
- Department of Interventional Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China (mainland)
| | - Tengfei Li
- Department of Interventional Radiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China (mainland)
| |
Collapse
|
21
|
Rao SNR, Pearse DD. Regulating Axonal Responses to Injury: The Intersection between Signaling Pathways Involved in Axon Myelination and The Inhibition of Axon Regeneration. Front Mol Neurosci 2016; 9:33. [PMID: 27375427 PMCID: PMC4896923 DOI: 10.3389/fnmol.2016.00033] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 05/02/2016] [Indexed: 01/06/2023] Open
Abstract
Following spinal cord injury (SCI), a multitude of intrinsic and extrinsic factors adversely affect the gene programs that govern the expression of regeneration-associated genes (RAGs) and the production of a diversity of extracellular matrix molecules (ECM). Insufficient RAG expression in the injured neuron and the presence of inhibitory ECM at the lesion, leads to structural alterations in the axon that perturb the growth machinery, or form an extraneous barrier to axonal regeneration, respectively. Here, the role of myelin, both intact and debris, in antagonizing axon regeneration has been the focus of numerous investigations. These studies have employed antagonizing antibodies and knockout animals to examine how the growth cone of the re-growing axon responds to the presence of myelin and myelin-associated inhibitors (MAIs) within the lesion environment and caudal spinal cord. However, less attention has been placed on how the myelination of the axon after SCI, whether by endogenous glia or exogenously implanted glia, may alter axon regeneration. Here, we examine the intersection between intracellular signaling pathways in neurons and glia that are involved in axon myelination and axon growth, to provide greater insight into how interrogating this complex network of molecular interactions may lead to new therapeutics targeting SCI.
Collapse
Affiliation(s)
- Sudheendra N R Rao
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine Miami, FL, USA
| | - Damien D Pearse
- The Miami Project to Cure Paralysis, University of Miami Miller School of MedicineMiami, FL, USA; The Department of Neurological Surgery, University of Miami Miller School of MedicineMiami, FL, USA; The Neuroscience Program, University of Miami Miller School of MedicineMiami, FL, USA; The Interdisciplinary Stem Cell Institute, University of Miami Miller School of MedicineMiami, FL, USA; Bruce W. Carter Department of Veterans Affairs Medical CenterMiami, FL, USA
| |
Collapse
|
22
|
Cattin AL, Burden JJ, Van Emmenis L, Mackenzie FE, Hoving JJA, Garcia Calavia N, Guo Y, McLaughlin M, Rosenberg LH, Quereda V, Jamecna D, Napoli I, Parrinello S, Enver T, Ruhrberg C, Lloyd AC. Macrophage-Induced Blood Vessels Guide Schwann Cell-Mediated Regeneration of Peripheral Nerves. Cell 2015; 162:1127-39. [PMID: 26279190 PMCID: PMC4553238 DOI: 10.1016/j.cell.2015.07.021] [Citation(s) in RCA: 580] [Impact Index Per Article: 64.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2015] [Revised: 06/11/2015] [Accepted: 06/30/2015] [Indexed: 12/22/2022]
Abstract
The peripheral nervous system has remarkable regenerative capacities in that it can repair a fully cut nerve. This requires Schwann cells to migrate collectively to guide regrowing axons across a 'bridge' of new tissue, which forms to reconnect a severed nerve. Here we show that blood vessels direct the migrating cords of Schwann cells. This multicellular process is initiated by hypoxia, selectively sensed by macrophages within the bridge, which via VEGF-A secretion induce a polarized vasculature that relieves the hypoxia. Schwann cells then use the blood vessels as "tracks" to cross the bridge taking regrowing axons with them. Importantly, disrupting the organization of the newly formed blood vessels in vivo, either by inhibiting the angiogenic signal or by re-orienting them, compromises Schwann cell directionality resulting in defective nerve repair. This study provides important insights into how the choreography of multiple cell-types is required for the regeneration of an adult tissue.
Collapse
Affiliation(s)
- Anne-Laure Cattin
- MRC Laboratory for Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Jemima J Burden
- MRC Laboratory for Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Lucie Van Emmenis
- MRC Laboratory for Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Francesca E Mackenzie
- Department of Cell Biology, UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Julian J A Hoving
- MRC Laboratory for Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK
| | | | - Yanping Guo
- UCL Cancer Institute, UCL, 72 Huntley Street, London WC1E 6DD, UK
| | - Maeve McLaughlin
- MRC Laboratory for Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Laura H Rosenberg
- MRC Laboratory for Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Victor Quereda
- MRC Laboratory for Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Denisa Jamecna
- MRC Laboratory for Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Ilaria Napoli
- MRC Laboratory for Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Simona Parrinello
- MRC Laboratory for Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Tariq Enver
- UCL Cancer Institute, UCL, 72 Huntley Street, London WC1E 6DD, UK
| | - Christiana Ruhrberg
- Department of Cell Biology, UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Alison C Lloyd
- MRC Laboratory for Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK; UCL Cancer Institute, UCL, 72 Huntley Street, London WC1E 6DD, UK.
| |
Collapse
|
23
|
Ronchi G, Haastert-Talini K, Fornasari BE, Perroteau I, Geuna S, Gambarotta G. The Neuregulin1/ErbB system is selectively regulated during peripheral nerve degeneration and regeneration. Eur J Neurosci 2015; 43:351-64. [DOI: 10.1111/ejn.12974] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 05/26/2015] [Accepted: 06/02/2015] [Indexed: 01/06/2023]
Affiliation(s)
- Giulia Ronchi
- Department of Clinical and Biological Sciences; University of Torino; Regione Gonzole 10 Orbassano 10043 Italy
- Neuroscience Institute of the ‘Cavalieri Ottolenghi’ Foundation (NICO); University of Torino; Orbassano Italy
| | - Kirsten Haastert-Talini
- Hannover Medical School; Institute of Neuroanatomy; Hannover Germany
- Center for Systems Neuroscience (ZSN); Hannover Germany
| | - Benedetta Elena Fornasari
- Department of Clinical and Biological Sciences; University of Torino; Regione Gonzole 10 Orbassano 10043 Italy
| | - Isabelle Perroteau
- Department of Clinical and Biological Sciences; University of Torino; Regione Gonzole 10 Orbassano 10043 Italy
- Neuroscience Institute of Torino (NIT); University of Torino; Orbassano Italy
| | - Stefano Geuna
- Department of Clinical and Biological Sciences; University of Torino; Regione Gonzole 10 Orbassano 10043 Italy
- Neuroscience Institute of the ‘Cavalieri Ottolenghi’ Foundation (NICO); University of Torino; Orbassano Italy
- Neuroscience Institute of Torino (NIT); University of Torino; Orbassano Italy
| | - Giovanna Gambarotta
- Department of Clinical and Biological Sciences; University of Torino; Regione Gonzole 10 Orbassano 10043 Italy
- Neuroscience Institute of Torino (NIT); University of Torino; Orbassano Italy
| |
Collapse
|
24
|
Neuregulin-1β Regulates the migration of Different Neurochemical Phenotypic Neurons from Organotypically Cultured Dorsal Root Ganglion Explants. Cell Mol Neurobiol 2015; 36:69-81. [DOI: 10.1007/s10571-015-0221-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 06/02/2015] [Indexed: 10/24/2022]
|
25
|
Chukhlieb M, Raasakka A, Ruskamo S, Kursula P. The N-terminal cytoplasmic domain of neuregulin 1 type III is intrinsically disordered. Amino Acids 2015; 47:1567-77. [PMID: 25944317 DOI: 10.1007/s00726-015-1998-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 04/21/2015] [Indexed: 11/30/2022]
Abstract
Axonally expressed neuregulin 1 (NRG1) type III is a transmembrane protein involved in various neurodevelopmental processes, including myelination and Schwann cell migration. NRG1 type III has one transmembrane domain and a C-terminal extracellular segment, which contains an epidermal growth factor homology domain. Little is known, however, about the intracellular N terminus of NRG1 type III, and the structure-function relationships of this cytoplasmic domain have remained uncharacterized. In the current study, we carried out the first structural and functional studies on the NRG1 type III cytoplasmic domain. Based on sequence analyses, the domain is predicted to be largely disordered, while a strictly conserved region close to the transmembrane segment may contain helical structure and bind metal ions. As shown by synchrotron radiation circular dichroism spectroscopy, the recombinant NRG1 type III cytoplasmic domain was disordered in solution, but it was able to fold partially into a helical structure, especially when both metals and membrane-mimicking compounds were present. NRG1 cytoplasmic tail binding to metals was further confirmed by calorimetry. These results suggest that the juxtamembrane segment of the NRG1 type III cytoplasmic domain may fold onto the membrane surface upon metal binding. Using synchrotron small-angle X-ray scattering, we further proved that the NRG1 cytoplasmic domain is intrinsically disordered, highly elongated, and behaves like a random polymer. Our work provides the first biochemical and biophysical data on the previously unexplored cytoplasmic domain of NRG1 type III, which will help elucidate the detailed structure-function relationships of this domain.
Collapse
Affiliation(s)
- Maryna Chukhlieb
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland
| | | | | | | |
Collapse
|
26
|
Reischauer S, Arnaout R, Ramadass R, Stainier DYR. Actin binding GFP allows 4D in vivo imaging of myofilament dynamics in the zebrafish heart and the identification of Erbb2 signaling as a remodeling factor of myofibril architecture. Circ Res 2014; 115:845-56. [PMID: 25228389 DOI: 10.1161/circresaha.115.304356] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
RATIONALE Dilated cardiomyopathy is a leading cause of congestive heart failure and a debilitating complication of antineoplastic therapies. Despite disparate causes for dilated cardiomyopathy, maladaptive cardiac remodeling and decreased systolic function are common clinical consequences, begging an investigation of in vivo contractile dynamics in development and disease, one that has been impossible to date. OBJECTIVE To image myocardial contractile filament dynamics in vivo and to assess potential causes of dilated cardiomyopathy in antineoplastic therapies targeting the epidermal growth factor receptor Erbb2. METHODS AND RESULTS We generated a transgenic zebrafish line expressing an actin-binding green fluorescent protein in cardiomyocytes, allowing an in vivo imaging of myofilaments. Analysis of this line revealed architectural differences in myofibrils of the distinct cardiomyocyte subtypes. We used this model to investigate the effects of Erbb2 signaling on myofibrillar organization because drugs targeting ERBB2 (HER2/NEU) signaling, a mainstay of breast cancer chemotherapy, cause dilated cardiomyopathy in many patients. High-resolution in vivo imaging revealed that Erbb2 signaling regulates a switch between a dense apical network of filamentous myofibrils and the assembly of basally localized myofibrils in ventricular cardiomyocytes. CONCLUSIONS Using this novel line, we compiled a reference for myofibrillar microarchitecture among myocardial subtypes in vivo and at different developmental stages, establishing this model as a tool to analyze in vivo cardiomyocyte contractility and remodeling for a broad range of cardiovascular questions. Furthermore, we applied this model to study Erbb2 signaling in cardiomyopathy. We show a direct link between Erbb2 activity and remodeling of myofibrils, revealing an unexpected mechanism with potentially important implications for prevention and treatment of cardiomyopathy.
Collapse
Affiliation(s)
- Sven Reischauer
- From the Department of Biochemistry and Biophysics (S.R., D.Y.R.S.) and Division of Cardiology, Department of Medicine, Cardiovascular Research Institute (R.A.), University of California, San Francisco; and Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (S.R., R.R., D.Y.R.S.).
| | - Rima Arnaout
- From the Department of Biochemistry and Biophysics (S.R., D.Y.R.S.) and Division of Cardiology, Department of Medicine, Cardiovascular Research Institute (R.A.), University of California, San Francisco; and Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (S.R., R.R., D.Y.R.S.)
| | - Radhan Ramadass
- From the Department of Biochemistry and Biophysics (S.R., D.Y.R.S.) and Division of Cardiology, Department of Medicine, Cardiovascular Research Institute (R.A.), University of California, San Francisco; and Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (S.R., R.R., D.Y.R.S.)
| | - Didier Y R Stainier
- From the Department of Biochemistry and Biophysics (S.R., D.Y.R.S.) and Division of Cardiology, Department of Medicine, Cardiovascular Research Institute (R.A.), University of California, San Francisco; and Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (S.R., R.R., D.Y.R.S.).
| |
Collapse
|
27
|
Gambarotta G, Ronchi G, Geuna S, Perroteau I. Neuregulin 1 isoforms could be an effective therapeutic candidate to promote peripheral nerve regeneration. Neural Regen Res 2014; 9:1183-5. [PMID: 25206780 PMCID: PMC4146285 DOI: 10.4103/1673-5374.135324] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/16/2014] [Indexed: 12/29/2022] Open
Affiliation(s)
- Giovanna Gambarotta
- Department of Clinical and Biological Sciences, University of Turin, Italy ; Neuroscience Institute of Turin (NIT), University of Turin, Italy
| | - Giulia Ronchi
- Department of Clinical and Biological Sciences, University of Turin, Italy ; Neuroscience Institute of the "Cavalieri Ottolenghi" Foundation (NICO), University of Turin, Italy
| | - Stefano Geuna
- Department of Clinical and Biological Sciences, University of Turin, Italy ; Neuroscience Institute of Turin (NIT), University of Turin, Italy ; Neuroscience Institute of the "Cavalieri Ottolenghi" Foundation (NICO), University of Turin, Italy
| | - Isabelle Perroteau
- Department of Clinical and Biological Sciences, University of Turin, Italy ; Neuroscience Institute of Turin (NIT), University of Turin, Italy
| |
Collapse
|
28
|
Wang Y, Wu X, Zhong Y, Shen J, Wu X, Ju S, Wang X. Effects of histone deacetylase inhibition on the survival, proliferation and migration of Schwann cells, as well as on the expression of neurotrophic factors and genes associated with myelination. Int J Mol Med 2014; 34:599-605. [PMID: 24888454 DOI: 10.3892/ijmm.2014.1792] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 05/06/2014] [Indexed: 11/06/2022] Open
Abstract
Trichostatin A (TSA), a histone deacetylase (HDAC) inhibitor, has been shown to have neuroprotective, neurotrophic and anti-inflammatory properties in both animal and cellular models of neurodegenerative disorders. In a previous study of ours, we demonstrated that TSA inhibited the proliferation and increased the differentiation of neuronal precursor cells (NPCs). However, the effects of TSA on Schwann cells (SCs) have not yet been fully elucidated. Thus, in the present study, using SCs derived from adult rat sciatic nerves, we investigated the effects of TSA on the survival, proliferation, migration and myelination of SCs. We found that TSA significantly induced SC death when used at high concentrations. We also observed that TSA promoted the proliferation of SCs in a time-dependent manner. In addition, TSA inhibited the migration of SCs. Moreover, RT-PCR revealed that TSA increased the mRNA expression of several neurotrophic factors and inhibited the expression of genes associated with myelination, including myelin basic protein (MBP) and myelin protein zero (MPZ). Taken together, our results suggest that TSA plays an important role in regulating the growth and biological function of SCs. These data may contribute to our understanding of TSA-based treatment of neurodegenerative diseases.
Collapse
Affiliation(s)
- Yazhou Wang
- Laboratory Medicine Center, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Xingjun Wu
- Department of Neurology, Xuhui Central Hospital, Xuhui, Shanghai 200031, P.R. China
| | - Yueping Zhong
- Department of Neurosurgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Jianhong Shen
- Department of Neurosurgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Xinhua Wu
- Surgical Comprehensive Laboratory, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Shaoqing Ju
- Laboratory Medicine Center, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| | - Xiaofei Wang
- Laboratory Medicine Center, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China
| |
Collapse
|
29
|
Van Raamsdonk CD, Deo M. Links between Schwann cells and melanocytes in development and disease. Pigment Cell Melanoma Res 2013; 26:634-45. [DOI: 10.1111/pcmr.12134] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 06/28/2013] [Indexed: 01/31/2023]
Affiliation(s)
| | - Mugdha Deo
- Department of Medical Genetics; University of British Columbia; Vancouver; BC; Canada
| |
Collapse
|
30
|
Repair of the Peripheral Nerve-Remyelination that Works. Brain Sci 2013; 3:1182-97. [PMID: 24961524 PMCID: PMC4061866 DOI: 10.3390/brainsci3031182] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 07/07/2013] [Accepted: 07/19/2013] [Indexed: 12/15/2022] Open
Abstract
In this review we summarize the events known to occur after an injury in the peripheral nervous system. We have focused on the Schwann cells, as they are the most important cells for the repair process and facilitate axonal outgrowth. The environment created by this cell type is essential for the outcome of the repair process. The review starts with a description of the current state of knowledge about the initial events after injury, followed by Wallerian degeneration, and subsequent regeneration. The importance of surgical repair, carried out as soon as possible to increase the chances of a good outcome, is emphasized throughout the review. The review concludes by describing the target re-innervation, which today is one of the most serious problems for nerve regeneration. It is clear, compiling this data, that even though regeneration of the peripheral nervous system is possible, more research in this area is needed in order to perfect the outcome.
Collapse
|