scholarly journals Major cellular events in peripheral nerve regeneration: A brief overview

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Naidu M ◽  
David P
Keyword(s):  
Peripheral Nerve ◽  
Schwann Cells ◽  
Wallerian Degeneration ◽  
Peripheral Nerve Regeneration ◽  
Scar Tissue ◽  
Regenerative Process ◽  
Cellular Events ◽  
Neural Cell Adhesion ◽  
Proximal Stump ◽  
Regeneration Response

Injury to a peripheral nerve leads to degeneration of the segment distal to the site of lesion, a process referred to as Wallerian degeneration. During Wallerian degeneration, axons and myelin sheaths undergo degeneration and are phagocytosed by macrophages and Schwann cells. The Schwann cells proliferate and the endoneurial tubes persist, together the whole structure is known as the band of Büngner. Within few hours, the damaged axons in the proximal stump initiate a regeneration response, with formation of new growth cones. During Wallerian degeneration, neurotrophins, neural cell adhesion molecules, cytokines and other soluble factors are upregulated to facilitate regeneration. The recovery of the target in mammals is often variable, but almost never complete. In humans, scar tissue forms at the site of lesion and this often results in poor recovery of the target. The major events underlying this regenerative process is highlighted and discussed in this review.

Early events of peripheral nerve regeneration

2005 ◽  
Vol 2 (2) ◽  
pp. 139-147 ◽  
Author(s):  
DAVID MCDONALD ◽  
CHU CHENG ◽  
YUANYUAN CHEN ◽  
DOUGLAS ZOCHODNE
Keyword(s):  
Peripheral Nerve ◽  
Peripheral Nerves ◽  
Wallerian Degeneration ◽  
De Novo ◽  
Peripheral Nerve Regeneration ◽  
Confocal Imaging ◽  
Double Labeling ◽  
Proximal Stump ◽  
Cell Processes ◽  
Early Regeneration

Early regeneration of injured peripheral nerves involves a series of events that are important in the success of eventual reconnection. In many nerve injuries, such as transections with gaps, axons and Schwann cells (SCs) penetrate into new microenvironments de novo, not involving zones of Wallerian degeneration. We studied unexplored axon–SC interactions by sampling of newly forming connections through a silicone conduit across transected rat sciatic peripheral nerve gaps. Axon and SC participation in bridge formation was addressed by light microscopy, electron microscopy and by double-labeling immunohistochemistry, including confocal imaging, and several, less appreciated aspects of early regrowth were identified. There are limitations to early and widespread regeneration of axons and SCs into bridges initially formed from connective tissue and blood vessels. Regrowth is ‘staggered’ such that only a small percentage of parent axons sampled the early bridge. There is an intimate, almost invariable relationship between SCs and extension of axons, which challenges the concept that axons lead and SCs follow. ‘Naked’ axons were infrequent and limited in scope. Axons did not seek out and adhere to vascular laminin but intimately followed laminin deposits associated with apposed SCs. Growth cones identified by labeling of β III tubulin, PGP 9.5 and GAP43/B50 were complex, implying a pause in their regrowth, and were most prominent at the proximal stump–regenerative bridge interface. There is surprising and substantial hostility to local regrowth of axons into newly forming peripheral nerve bridges. Early axon outgrowth, associated with apposed Schwann cell processes, is highly constrained even when not exposed to adjacent myelin and products of Wallerian degeneration.

Resorbable Structures for Schwann Cell Enhanced Peripheral Nerve Regeneration

1998 ◽  
Vol 550 ◽  
Author(s):  
A.E. Silva ◽  
LC. Summerhayes ◽  
D.J. Trantolo ◽  
D.L. Wise ◽  
M.V. Catftaneo ◽  
...  
Keyword(s):  
Growth Factor ◽  
Schwann Cell ◽  
Peripheral Nerve ◽  
Nerve Regeneration ◽  
Schwann Cells ◽  
Peripheral Nerve Regeneration ◽  
Cell Movement ◽  
Regenerative Process

AbstractSchwann cells play a dual role serving as a physical framework for regenerating nerves, providing extracellular matrix proteins and specific adhesion molecules facilitating attachment and cell movement, and as a source of stimulatory factors mediated by the release or reception of different ligands important in growth and cell signaling events. To investigate the role of one such ligand, glial growth factor (GGF), in peripheral nerve regeneration, a bioabsorbable nerve guide, prepared from a poly(lactic-co-glycolic) acid (PLGA) foam was seeded with autogenous Schwann cells in the presence and absence of growth factor and evaluated in vivo using a rat sciatic nerve regeneration model. Four weeks post-operatively peripheral nerve regeneration was evident. The resorbable foam implant demonstrated extensive neo-vascularization in and around the guide with no evidence of an inflammatory response or encapsulation. The study showed a statistically significant increase in all measured parameters of nerve regeneration in the presence of GGF. Increased numbers of blood vessels in the regenerated tissue accompanied increased total axon counts after twelve weeks. The addition of exogenous Schwann cells resulted in reduced total axon counts perhaps due to the competition for limited growth factors released by the regenerating tissues. The Schwann cell groups, however, displayed the highest myelination indices recorded likely reflecting the role of Schwann cells in the myelination process. Measurements of conduction velocities (EMGs) revealed the highest conductance velocities recorded in nerves regenerated in the presence of both GGF and Schwann cells. Clearly, the inclusion of GGF in the nerve regenerative process is beneficial with respect to both the generation of new axons and the establishment of a functional endpoint.

scholarly journals Histopathological analysis of gangliosides use in peripheral nerve regeneration after axonotmesis in rats

2008 ◽  
Vol 23 (4) ◽  
pp. 364-371 ◽  
Author(s):  
Camila Maria Beder Ribeiro ◽  
Belmiro Cavalcanti do Egito Vasconcelos ◽  
Joaquim Celestino da Silva Neto ◽  
Valdemiro Amaro da Silva Júnior ◽  
Nancy Gurgel Figueiredo
Keyword(s):  
Sciatic Nerve ◽  
Peripheral Nerve ◽  
Nerve Regeneration ◽  
Schwann Cells ◽  
Peripheral Nerve Regeneration ◽  
Cell Activity ◽  
Control Group ◽  
Histopathological Analysis ◽  
Male Wistar Rats ◽  
The Right

PURPOSE: To analyze the action of gangliosides in peripheral nerve regeneration in the sciatic nerve of the rat. METHODS: The sample was composed of 96 male Wistar rats. The animals were anaesthetized and, after identification of the anaesthesic plane, an incision was made in the posterior region of the thigh, followed by skin and muscle divulsion. The right sciatic nerve was isolated and compressed for 2 minutes. Continuous suture of the skin was performed. The animals were randomly divided into two groups: the experimental group (EG), which received subcutaneous injection of gangliosides, and the control group (CG), which received saline solution (0.9%) to mimic the effects of drug administration. RESULTS: No differences were observed between the experimental and control groups evaluated on the eighth day of observation. At 15 and 30 days the EG showed an decrease in Schwann cell activity and an apparent improvement in fibre organization; at 60 days, there was a slight presence of Schwann cells in the endoneural space and the fibres were organized, indicating nerve regeneration. At 15 and 30 days, the level of cell reaction in the CG had diminished, but there were many cells with cytoplasm in activity and in mitosis; at 60 days, hyperplastic Schwann cells and mitotic activity were again observed, as well as nerve regeneration, but to a lesser extent than in the EG. CONCLUSION: The administration of exogenous gangliosides seems to improve nerve regeneration.

scholarly journals ATP Release through Lysosomal Exocytosis from Peripheral Nerves: The Effect of Lysosomal Exocytosis on Peripheral Nerve Degeneration and Regeneration after Nerve Injury

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Junyang Jung ◽  
Hyun Woo Jo ◽  
Hyunseob Kwon ◽  
Na Young Jeong
Keyword(s):  
Peripheral Nerve ◽  
Schwann Cells ◽  
Nerve Injury ◽  
Peripheral Nerves ◽  
Wallerian Degeneration ◽  
Atp Release ◽  
Nerve Degeneration ◽  
Peripheral Neurons ◽  
Charcot Marie Tooth Disease ◽  
Axonal Degradation

Studies have shown that lysosomal activation increases in Schwann cells after nerve injury. Lysosomal activation is thought to promote the engulfment of myelin debris or fragments of injured axons in Schwann cells during Wallerian degeneration. However, a recent interpretation of lysosomal activation proposes a different view of the phenomenon. During Wallerian degeneration, lysosomes become secretory vesicles and are activated for lysosomal exocytosis. The lysosomal exocytosis triggers adenosine 5′-triphosphate (ATP) release from peripheral neurons and Schwann cells during Wallerian degeneration. Exocytosis is involved in demyelination and axonal degradation, which facilitate nerve regeneration following nerve degeneration. At this time, released ATP may affect the communication between cells in peripheral nerves. In this review, our description of the relationship between lysosomal exocytosis and Wallerian degeneration has implications for the understanding of peripheral nerve degenerative diseases and peripheral neuropathies, such as Charcot-Marie-Tooth disease or Guillain-Barré syndrome.

The Astrocyte Inhibition of Peripheral Nerve Regeneration Is Reversed by Schwann Cells

1994 ◽  
Vol 126 (1) ◽  
pp. 44-60 ◽  
Author(s):  
Véronique Guénard ◽  
Patrick Aebischer ◽  
Richard P. Bunge
Keyword(s):  
Peripheral Nerve ◽  
Nerve Regeneration ◽  
Schwann Cells ◽  
Peripheral Nerve Regeneration
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