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Biocompatibility and efficacy of five-channel and eight-channel crosslinked urethane-doped polyester elastomers (CUPEs) as nerve guidance conduit for reconstruction of segmental peripheral nerve defect using rat modelHo, Wing-hang, Angela, 何穎恆 January 2013 (has links)
Introduction
Peripheral nerve injury is common in clinical practice. The usual etiologies are penetrating injury, stretch, compression, crush and ischemia. Outcome of nerve injury depends on the etiology and also the management. Nerve defect is a challenging scenario. The current gold standard of managing a nerve defect is autologous nerve graft.
However, due to the selection of nerve graft and donor site morbidity, artificial nerve conduits are gaining popularity. However, there are drawbacks of single hollow conduit such as lack of internal support to prevent conduit collapse and inability so as to recreate the proper native spatial arrangement of cells and extracellular matrix within the conduit. In this study, the biocompatibility and efficacy of five-channel and eight-channel Crosslinked Urethane-doped Polyester Elastomers (CUPEs) as nerve guidance conduit will be evaluated through a rat model with reconstruction of segmental peripheral nerve defect.
Material and method
Eighteen adult Sprague-Dawley rats were used. Tthey were randomly allocated to three groups: autograft group, five-channel conduit group and eight-channel conduit group with each consisted of six rats. A 10mm nerve defects were created at the right sciatic nerve. They were bridged with reverse autograft, 5-channel conduit and 8-channel conduit. After eight weeks the rats were euthanized and the reconstructed nerves were harvested for histomorphometric analysis.
Results
All conduits showed regenerated nerve tissue inside. There was no collapse of the conduits. There were no severe tissue reaction or scarring near the reconstructed nerve. No neuroma was formed. Histomorphometric analysis showed nerve regeneration was enhanced with increasing number of channels inside conduit. There was overall drop in fiber density between proximal and distal segment among all groups.
Conclusions
CUPE nerve guidance conduit is biocompatible and shows good nerve regeneration in reconstructing nerve defect. / published_or_final_version / Obstetrics and Gynaecology / Master / Master of Medical Sciences
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Flexible nerve guidance conduit for peripheral nerve regenerationChoy, Wai-man., 蔡維敏. January 2012 (has links)
The golden method of peripheral nerve system injury is the nerve autograft, but it is associated with
drawbacks such as donor site morbidity, needs of second incisions and the shortage of nerve grafts.
Comparatively, connecting the nerve defect directly is an alternative. Unfortunately, if the defects
are long, the induced tension will deteriorate the nerve regeneration. These limitations led to the
development of artificial nerve guidance conduit (NGC). The market available NGC have problems
of unsatisfactory functional recovery and may collapse after the implantation. These are attributed
to material and structural deficiencies. Therefore, there is essential to study a biomaterial, which has
excellent biological and physical properties to fit the NGC application. In addition, some studies
suggested that the poor functional recovery resulted from the NGC implantation were due to the
lack of micro-guidance inside the conduit. Thus, it is necessary to investigate the structural
influence on the functional recovery of peripheral nerve injury.
Crosslinked urethane-doped polyester elastomer (CUPE) is newly invented for a blood vessel graft
because it possesses similar mechanical properties of blood vessel which is similar to nerve as well.
Therefore, CUPE was also considered to be the NGC. Its biocompatibility has been proved to be
excellent in the previous study done by Dr. Andrew SL, Ip. Targeting on the long peripheral nerve
regeneration, the aims of this study are (1) to investigate the biocompatibility of CUPE in in-vitro
condition and (2) to study the influence of nerve-like structure on the peripheral nerve system injury
in an animal model. The ultimate goal is to enhance the functional recovery of peripheral nerve
system injury by implanting a flexible biomaterial, CUPE, which has a nerve-like microarchitecture.
It is hypothesized that the nerve-like structure can promote the axonal regeneration.
The surface energy and roughness of CUPE were investigated. It showed a relatively low surface
energy compared to other conventional biopolymers such that the cell adhesion and also the
proliferation were inhibited. Therefore, the CUPE was modified by the immersion into a high
glucose DMEM. The change in the hydrophilicity, roughness and cell viability of medium treated
CUPE were studied. The hydrophilicity of treated CUPE was increased but the roughness was
remaining unchanged whereas the pH of the immersion solution did not cause any effect on the cell
activity on the CUPE. In the pilot animal study, five channels along the CUPE-NGC had a similar
myelinated fiber density and population compared to the nerve autograft. Also, the channels in the
CUPE-NGC were fragmented.
In summary, the medium treatment could enhance the hydrophilicity of CUPE and the cell activity
on CUPE. Such modifications did not governed by the pH of the medium. The NGC-CUPE with
five channels, which imitated a basic nerve structure was shown to have a similar tissue
regeneration and the functional recovery as the nerve autograft did. The results proved the
hypothesis that the nerve-like structure can promote the functional recovery of peripheral nerve
system injury with the use of a new biomaterial, CUPE as the NGC substrate. / published_or_final_version / Orthopaedics and Traumatology / Master / Master of Philosophy
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The morphological plasticity of Retiral ganglion cells during development and regeneration: a luciferyellow intracellular injection study劉錦昌, Lau, Kam-cheung. January 1991 (has links)
published_or_final_version / Anatomy / Doctoral / Doctor of Philosophy
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Zinc-finger transcription factors and the response of non-myelinating Schwann cells to axonal injuryEllerton, Elaine Louise 29 August 2008 (has links)
Not available / text
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Axonal regrowth and morphological plasticity of retinal ganglion cellsin the adult hamster左雨鵬, Cho, Yu-pang, Eric. January 1990 (has links)
published_or_final_version / Anatomy / Doctoral / Doctor of Philosophy
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The ultrastructural characteristics of the reinnervating neuromuscular junctionLakia, Brent M. January 2006 (has links)
Since the discovery of peripheral nerve regeneration nearly a century ago, the mechanisms that guide this regeneration have been elusive. This project aimed to describe how an axon is able to traverse the environment of the body and precisely reinnervate its target cell. Using a novel technique of combining light and electron microscopy, I observed reinnervating axons in transgenic mice to answer the questions of whether Schwann cells are an important guidance cue for the motor neuron and whether the outgrowing axon is fully developed or the process is a step-wise process of activation. The data suggests that Schwann cell contact is important for the tip of the regenerating axon to guide the axon back to its synapse on the muscle fiber. Further, it seems that the tip of the axon is not capable of synaptic transmission as it lacks active zones, suggesting that reinnervation is a step-wise process. / Department of Physiology and Health Science
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