Hierarchical thermoplastic rippled nanostructures regulate Schwann cell adhesion, morphology and spatial organization

Nanoscale ◽  
2017 ◽  
Vol 9 (39) ◽  
pp. 14861-14874 ◽  
Author(s):  
Cecilia Masciullo ◽  
Rossana Dell'Anna ◽  
Ilaria Tonazzini ◽  
Roman Böettger ◽  
Giancarlo Pepponi ◽  
...  

Hierarchical rippled nanotopographies are produced in PET. The effects of these nano-ripples on Schwann Cells are studied for nerve-repair applications.

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Laura J Wagstaff ◽  
Jose A Gomez-Sanchez ◽  
Shaline V Fazal ◽  
Georg W Otto ◽  
Alastair M Kilpatrick ◽  
...  

After nerve injury, myelin and Remak Schwann cells reprogram to repair cells specialized for regeneration. Normally providing strong regenerative support, these cells fail in aging animals, and during chronic denervation that results from slow axon growth. This impairs axonal regeneration and causes significant clinical problems. In mice, we find that repair cells express reduced c-Jun protein as regenerative support provided by these cells declines during aging and chronic denervation. In both cases, genetically restoring Schwann cell c-Jun levels restores regeneration to control levels. We identify potential gene candidates mediating this effect and implicate Shh in the control of Schwann cell c-Jun levels. This establishes that a common mechanism, reduced c-Jun in Schwann cells, regulates success and failure of nerve repair both during aging and chronic denervation. This provides a molecular framework for addressing important clinical problems, suggesting molecular pathways that can be targeted to promote repair in the PNS.


1986 ◽  
Vol 103 (6) ◽  
pp. 2439-2448 ◽  
Author(s):  
R Martini ◽  
M Schachner

The cellular and subcellular localization of the neural cell adhesion molecules L1, N-CAM, and myelin-associated glycoprotein (MAG), their shared carbohydrate epitope L2/HNK-1, and the myelin basic protein (MBP) were studied by pre- and post-embedding immunoelectron microscopic labeling procedures in developing mouse sciatic nerve. L1 and N-CAM showed a similar staining pattern. Both were localized on small, non-myelinated, fasciculating axons and axons ensheathed by non-myelinating Schwann cells. Schwann cells were also positive for L1 and N-CAM in their non-myelinating state and at the onset of myelination, when the Schwann cell processes had turned approximately 1.5 loops. Thereafter, neither axon nor Schwann cell could be detected to express the L1 antigen, whereas N-CAM was found in the periaxonal area and, more weakly, in compact myelin of myelinated fibers. Compact myelin, Schmidt-Lanterman incisures, paranodal loops, and finger-like processes of Schwann cells at nodes of Ranvier were L1-negative. At the nodes of Ranvier, the axolemma was also always L1- and N-CAM-negative. The L2/HNK-1 carbohydrate epitope coincided in its cellular and subcellular localization most closely to that observed for L1. MAG appeared on Schwann cells at the time L1 expression ceased. MAG was then expressed at sites of axon-myelinating Schwann cell apposition and non-compacted loops of developing myelin. When compaction of myelin occurred, MAG remained present only at the axon-Schwann cell interface; Schmidt-Lanterman incisures, inner and outer mesaxons, and paranodal loops, but not at finger-like processes of Schwann cells at nodes of Ranvier or compacted myelin. All three adhesion molecules and the L2/HNK-1 epitope could be detected in a non-uniform staining pattern in basement membrane of Schwann cells and collagen fibrils of the endoneurium. MBP was detectable in compacted myelin, but not in Schmidt-Lanterman incisures, inner and outer mesaxon, paranodal loops, and finger-like processes at nodes of Ranvier, nor in the periaxonal regions of myelinated fibers, thus showing a complementary distribution to MAG. These studies show that axon-Schwann cell interactions are characterized by the sequential appearance of cell adhesion molecules and MBP apparently coordinated in time and space. From this sequence it may be deduced that L1 and N-CAM are involved in fasciculation, initial axon-Schwann cell interaction, and onset of myelination, with MAG to follow and MBP to appear only in compacted myelin. In contrast to L1, N-CAM may be further involved in the maintenance of compact myelin and axon-myelin apposition of larger diameter axons.


2021 ◽  
Vol 13 ◽  
Author(s):  
Anjali Balakrishnan ◽  
Lauren Belfiore ◽  
Tak-Ho Chu ◽  
Taylor Fleming ◽  
Rajiv Midha ◽  
...  

Peripheral nerve injuries arising from trauma or disease can lead to sensory and motor deficits and neuropathic pain. Despite the purported ability of the peripheral nerve to self-repair, lifelong disability is common. New molecular and cellular insights have begun to reveal why the peripheral nerve has limited repair capacity. The peripheral nerve is primarily comprised of axons and Schwann cells, the supporting glial cells that produce myelin to facilitate the rapid conduction of electrical impulses. Schwann cells are required for successful nerve regeneration; they partially “de-differentiate” in response to injury, re-initiating the expression of developmental genes that support nerve repair. However, Schwann cell dysfunction, which occurs in chronic nerve injury, disease, and aging, limits their capacity to support endogenous repair, worsening patient outcomes. Cell replacement-based therapeutic approaches using exogenous Schwann cells could be curative, but not all Schwann cells have a “repair” phenotype, defined as the ability to promote axonal growth, maintain a proliferative phenotype, and remyelinate axons. Two cell replacement strategies are being championed for peripheral nerve repair: prospective isolation of “repair” Schwann cells for autologous cell transplants, which is hampered by supply challenges, and directed differentiation of pluripotent stem cells or lineage conversion of accessible somatic cells to induced Schwann cells, with the potential of “unlimited” supply. All approaches require a solid understanding of the molecular mechanisms guiding Schwann cell development and the repair phenotype, which we review herein. Together these studies provide essential context for current efforts to design glial cell-based therapies for peripheral nerve regeneration.


2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Chenyu Chu ◽  
Jia Deng ◽  
Cong Cao ◽  
Yi Man ◽  
Yili Qu

Collagen is an essential component of the extracellular matrix (ECM) and is a suitable material for nerve repair during tissue remodeling for fracture repair. Epigallocatechin-3-gallate (EGCG), an extract of green tea, shows various biological activities that are beneficial to nerve repair. Here, we developed modified collagen containing different concentrations of EGCG (0.0064%, 0.064%, and 0.64%, resp.) to induce Schwann cell proliferation and differentiation. Cell Counting Kit-8 test, live/dead assay, and SEM showed that collagen cross-linked by EGCG induced Schwann cell proliferation. Real-time polymerase chain reaction, enzyme-linked immunosorbent assay, and Western blotting revealed that EGCG-modified collagen induced Schwann cell differentiation and downregulated reactive oxygen species (ROS) levels by downregulating the MAPK P38 signaling pathway. Our results indicate that collagen cross-linked with an appropriate concentration of EGCG induces the proliferation and differentiation of Schwann cells. The EGCG-modified collagen membrane may be applicable for nerve repair and guided tissue regeneration applications.


2020 ◽  
Author(s):  
Laura J. Wagstaff ◽  
Jose A. Gomez-Sanchez ◽  
Shaline V. Fazal ◽  
Georg W. Otto ◽  
Alastair M. Kilpatrick ◽  
...  

ABSTRACTAfter nerve injury, myelin and Remak Schwann cells reprogram to repair cells specialized for regeneration. Normally providing strong regenerative support, these cells fail in aging animals, and during the chronic denervation that results from the slow growth of axons. This impairs axonal regeneration and causes a significant clinical problem. In mice, we find that repair cells express reduced c-Jun protein as the regenerative support provided by these cells declines in aging animals and during chronic denervation. In both cases, genetically restoring Schwann cell c-Jun levels restores regeneration to that in controls. We identify potential gene candidates mediating this effect and implicate Shh in the control of Schwann cell c-Jun levels. This establishes that a common mechanism, reduced c-Jun in Schwann cells, regulates the success and failure of nerve repair both during aging and chronic denervation. This provides a molecular framework for addressing important clinical problems, and suggests molecular pathways that can be targeted to promote repair in the PNS.


2006 ◽  
Vol 104 (5) ◽  
pp. 778-786 ◽  
Author(s):  
Kirsten Haastert ◽  
Christina Mauritz ◽  
Cordula Matthies ◽  
Claudia Grothe

Object The purpose of this study was to provide genetically modified adult human Schwann cells as tools for cell transplantation in peripheral nerve repair. The application of transfected autologous Schwann cells overexpressing regeneration-promoting proteins, for example, neurotrophic or growth factors, is a promising approach in the aforementioned context. To achieve an optimal clinical outcome, it is highly important to perform enrichment, genetic modification, and retransplantation of cells in a short time. Methods To enable the development of these autologous cellular prostheses, the authors tested the properties of adult human Schwann cells obtained from differently treated human peripheral nerve biopsy samples. The use of “cold jet,” a fast and effective enrichment procedure, as well as selective, serum-free culture conditions, resulted in very pure adult human Schwann cell cultures. Using an optimized electroporation protocol, as many as 48.4% of adult human Schwann cells were successfully transfected. Conclusions The authors present a very fast protocol to establish adult human Schwann cell cultures that demonstrably express plasmid proteins after plasmid DNA insertion by electroporation. These autologous human Schwann cells transfected to enhance the endogenous production of regeneration-supporting proteins will likely constitute a major component of tissue-engineered peripheral nerve grafts.


2008 ◽  
Vol 33 (5) ◽  
pp. 587-594 ◽  
Author(s):  
D. F. KALBERMATTEN ◽  
P. ERBA ◽  
D. MAHAY ◽  
M. WIBERG ◽  
G. PIERER ◽  
...  

Many strategies have been investigated to provide an ideal substitute to treat a nerve gap injury. Initially, silicone conduits were used and more recently conduits fabricated from natural materials such as poly-3-hydroxybutyrate (PHB) showed good results but still have their limitations. Surgically, a new concept optimising harvested autologous nerve graft has been introduced as the single fascicle method. It has been shown that a single fascicle repair of nerve grafting is successful. We investigated a new approach using a PHB strip seeded with Schwann cells to mimic a small nerve fascicle. Schwann cells were attached to the PHB strip using diluted fibrin glue and used to bridge a 10-mm sciatic nerve gap in rats. Comparison was made with a group using conventional PHB conduit tubes filled with Schwann cells and fibrin glue. After 2 weeks, the nerve samples were harvested and investigated for axonal and Schwann cell markers. PGP9.5 immunohistochemistry showed a superior nerve regeneration distance in the PHB strip group versus the PHB tube group (> 10 mm, crossed versus 3.17± 0.32 mm respectively, P<0.05) as well as superior Schwann cell intrusion (S100 staining) from proximal (> 10 mm, crossed versus 3.40± 0.36 mm, P<0.01) and distal (> 10 mm, crossed versus 2.91± 0.31 mm, P<0.001) ends. These findings suggest a significant advantage of a strip in rapidly connecting a nerve gap lesion and imply that single fascicle nerve grafting is advantageous for nerve repair in rats.


2018 ◽  
Author(s):  
Weili Tian ◽  
Tim Czopka ◽  
Hernán López-Schier

ABSTRACTThe obligate pro-degenerative protein Sarm1 is essential for Wallerian axon degeneration. Inhibition of Sarm1 has been proposed as a promising neuroprotective strategy with clinical relevance. Yet, the conditions that will most benefit from inhibiting Sarm1 remain undefined. Here we use genetics and pharmacology in zebrafish to show that systemic elimination of Sarm1 is glioprotective. Loss of Sarm1 does not affect macrophage recruitment to the wound microenvironment, focal injury resolution, or nerve repair. Unexpectedly, Sarm1 deficiency increases Schwann-cell resistance to toxicity by diverse chemotherapeutic agents after neuronal injury. Yet, synthetic degradation of Sarm1-deficient severed axons reversed this effect, suggesting that glioprotection is non-cell-autonomous. These findings anticipate that interventions aimed at inhibiting Sarm1 can counter heightened glial vulnerability to chemical stressors and may be an effective strategy to reduce chronic consequences of neurotrauma.


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