Segment Of Sciatic Nerve Research Articles

Transplantation of Preconditioned Schwann Cells Following Hemisection Spinal Cord Injury

Chronically compressed sciatic nerve segments were transplanted to hemisected spinal cord injured rats. Histologic evaluation and behavior functional outcomes were tested after 6 weeks following surgery. To evaluate the outcome of preconditioned peripheral nerves as a permissive environment in axonal regeneration of the injured spinal cord. Schwann cells have been used to facilitate a permissive environment for the injured spinal cord to regenerate. Previous experiments have shown compressive mechanical stress to be important in stimulating the regenerative behavior of Schwann cells. Transplantation of highly permissive Schwann cell-enriched peripheral nerve grafts may enhance regeneration in spinal cord injury. Adult Sprague-Dawley rats (n = 24) were used to create a hemisection injury of the spinal cord. At 1-week postinjury creation, the spinal cords were reexposed for all animals. Peripheral nerve grafts were obtained from rat sciatic nerve, either untreated or subjected to mechanical compression for 2 weeks with nonconstrictive tubing. Transplantation of grafts was performed after a resection of the glial scar. Functional outcome was measured using the Basso, Beattie, Bresnahan Locomotor Rating Score and footprint analysis. Tract tracing of descending and ascending spinal cord tracts was performed at 6 weeks after surgery for histologic evaluation of axonal regeneration. Preconditioned transplants had significantly higher Basso, Beattie, Bresnahan Scores versus hemisection alone in the late postoperative period (P < 0.05). They also had significantly less foot exorotation and base of support when compared to nonconditioned transplants. Histologic analysis showed increased regeneration at lesional sites for preconditioned transplants versus control group (P < 0.05). Functional recovery after hemisection injury improved significantly in the late postoperative period with transplantation of preconditioned peripheral nerve. Preconditioned grafts also exhibit sustained axonal regeneration at and past the lesional site in histologic analysis. Further investigation with later time points is warranted.

Impaired Axonal Regeneration by Isolectin B4-Binding Dorsal Root Ganglion NeuronsIn Vitro

The subpopulation of dorsal root ganglion (DRG) neurons recognized by Griffonia simplicifolia isolectin B4 (IB4) differ from other neurons by expressing receptors for glial cell line-derived neurotrophic factor (GDNF) rather than neurotrophins. Additionally, IB4-labeled neurons do not express the laminin receptor, alpha7-integrin (Gardiner et al., 2005), necessary for optimal axonal regeneration in the peripheral nervous system. In cultures of dissociated DRG neurons of adult mice on laminin, robust spontaneous neurite outgrowth from IB4-negative neurons occurs and is strongly enhanced by previous axotomy. In contrast, IB4-labeled neurons show little neurite outgrowth and do not express GAP 43, even after axotomy or culture with GDNF. Moreover, growth of their axons through collagen gels is impaired compared with other DRG neurons. To determine whether the sparse neurite outgrowth of IB4-labeled neurons is attributable to lack of integrin expression, DRG cultures were infected with a herpes simplex 1 vector encoding alpha7-integrin, but its forced expression failed to promote neurite outgrowth in either IB4-labeled or other DRG neurons or in cultured adult retinal ganglion cells. Forced coexpression of both alpha7-integrin and GAP 43 also failed to promote neurite outgrowth in IB4-labeled neurons. In addition, cultured sciatic nerve segments were found to release much lower levels of GDNF, demonstrated by ELISA, than nerve growth factor. These findings together with their impaired intrinsic axonal regeneration capacity may contribute to the known vulnerability of the IB4-labeled population of DRG neurons to peripheral nerve injury.

Successful storage of peripheral nerves using University of Wisconsin solution with polyphenol

We have previously reported that green tea polyphenol can preserve peripheral nerve segments for up to 1 month. In this study, we investigated the effect on peripheral nerve preservation of adding polyphenol to the conventional University of Wisconsin solution (UW solution), which has been widely used for organ storage. Twenty millimeter-long sciatic nerve segments, harvested from Lewis rats, were immersed in UW solution containing polyphenol (1 mg/mL) for 1 week and then in UW solution alone at 4 °C for 3 additional weeks before transplantation into recipient Lewis rats. Neural cell viability of the preserved nerve segments was confirmed by vital staining (calcein-AM/ethidium homodimer), electron microscopy, and genomic studies. Morphologically, nerve regeneration was similar to that of fresh isografts and superior to that of grafts stored with UW solution alone. Moreover, the electrophysiological results were equal to those of fresh isografts. Polyphenol has the potential to be used for peripheral nerve storage and could be useful for routine peripheral nerve banking.

Propagation of scrapie in peripheral nerves after footpad infection in normal and neurotoxin exposed hamsters

As is known from various animal models, the spread of agents causing transmissible spongiform encephalopathies (TSE) after peripheral infection affects peripheral nerves before reaching the central nervous system (CNS) and leading to a fatal end of the disease. The lack of therapeutic approaches for TSE is partially due to the limited amount of information available on the involvement of host biological compartments and processes in the propagation of the infectious agent. The in vivo model presented here can provide information on the spread of the scrapie agent via the peripheral nerves of hamsters under normal and altered axonal conditions. Syrian hamsters were unilaterally footpad (f.p.) infected with scrapie. The results of the spatiotemporal ultrasensitive immunoblot-detection of scrapie-associated prion protein (PrP(Sc)) in serial nerve segments of both distal sciatic nerves could be interpreted as a centripetal and subsequent centrifugal neural spread of PrP(Sc) for this route of infection. In order to determine whether this propagation is dependent on main components in the axonal cytoskeleton (e.g. neurofilaments, also relevant for the component ;a' of slow axonal transport mechanisms), hamsters were treated -in an additional experiment- with the neurotoxin beta,beta-iminodiproprionitrile (IDPN) around the beginning of the scrapie infection. A comparison of the Western blot signals of PrP(Sc) in the ipsilateral and in the subsequently affected contralateral sciatic nerve segments with the results revealed from IDPN-untreated animals at preclinical and clinical stages of the TSE disease, indicated similar amounts of PrP(Sc). Furthermore, the mean survival time was unchanged in both groups. This in vivo model, therefore, suggests that the propagation of PrP(Sc) along peripheral nerves is not dependent on an intact neurofilament component of the axonal cytoskeleton. Additionally, the model indicates that the spread of PrP(Sc) is not mediated by the slow component ;a' of the axonal transport mechanism.

Axonal transport of BDNF precursor in primary sensory neurons

Recent studies have shown that the precursor of brain-derived neurotrophic factor (pro-BDNF) activates p75NTR with high affinity to induce apoptosis. Here we show that pro-BDNF is transported anterogradely and retrogradely in sensory neurons of adult rats. After a crush injury of sciatic nerves, dorsal roots or dorsal column in adult Sprague-Dawley rats, the immunoreactivity for pro-BDNF accumulated at both the proximal and distal segments. The accumulation reached a maximum at 24 h after injury. Western blot analysis also revealed pro-BDNF in sciatic nerve segments proximal and distal to the ligature and in the spinal cord. Biotinylated or Alexa-488-labelled pro-BDNF injected into sciatic nerve was internalized and transported both retrogradely and anterogradely within sensory neurons. These results demonstrate that pro-BDNF is anterogradely and retrogradely transported in sensory neurons, suggesting that endogenous pro-BDNF may be released and play important functions.

Axonal transports of tripeptidyl peptidase II in rat sciatic nerves

Axonal transport of tripeptidyl peptidase II, a putative cholecystokinin inactivating serine peptidase, was examined in the proximal, middle, and distal segments of rat sciatic nerves using a double ligation technique. Enzyme activity significantly increased not only in the proximal segment but also in the distal segment 12–72 h after ligation, and the maximal enzyme activity was found in the proximal and distal segments at 72 h. Western blot analysis of tripeptidyl peptidase II showed that its immunoreactivities in the proximal and distal segments were 3.1- and 1.7-fold higher than that in the middle segment. The immunohistochemical analysis of the segments also showed an increase in immunoreactive tripeptidyl peptidase II level in the proximal and distal segments in comparison with that in the middle segment, indicating that tripeptidyl peptidase II is transported by anterograde and retrograde axonal flow. The results suggest that tripeptidyl peptidase II may be involved in the metabolism of neuropeptides in nerve terminals or synaptic clefts.

Upregulation of chondroitin 6-sulphotransferase-1 facilitates Schwann cell migration during axonal growth

Cell migration is central to development and post-traumatic regeneration. The differential increase in 6-sulphated chondroitins during axonal growth in both crushed sciatic nerves and brain development suggests that chondroitin 6-sulphotransferase-1 (C6ST-1) is a key enzyme that mediates cell migration in the process. We have cloned the cDNA of the C6ST-1 gene (C6st1) (GenBank accession number AF178689) from crushed sciatic nerves of adult rats and produced ribonucleotide probes accordingly to track signs of 6-sulphated chondroitins at the site of injury. We found C6st1 mRNA expression in Schwann cells emigrating from explants of both sciatic nerve segments and embryonic dorsal root ganglia. Immunocytochemistry indicated pericellular 6-sulphated chondroitin products around C6ST-1-expressing frontier cells. Motility analysis of frontier cells in cultures subjected to staged treatment with chondroitinase ABC indicated that freshly produced 6-sulphated chondroitin moieties facilitated Schwann cell motility, unlike restrictions resulting from proteoglycan interaction with matrix components. Sciatic nerve crush provided further evidence of in vivo upregulation of the C6ST-1 gene in mobile Schwann cells that guided axonal regrowth 1-14 days post crush; downregulation then accompanied declining mobility of Schwann cells as they engaged in the myelination of re-growing axons. These findings are the first to identify upregulated C6st1 gene expression correlating with the motility of Schwann cells that guide growing axons through both developmental and injured environments.

September 13 Highlights

Sahenk et al. examined efficacy of NT-3 treatment in animal models and in a randomized controlled pilot trial in patients with CMT1A. NT-3 augmented axonal regeneration in the animal models, improved sensory scores of patients, and increased the number of small myelinated fibers in sural nerves. ![][1] figure. NT-3 treated (A), regenerating axons in (A), untreated (B), and BDNF treated nude mice (C) at 8 weeks. see page 681 The editorial by Pleasure and Chance considers the mechanism by which NT-3 enhances regeneration of myelinated axons in CMT1A, a disorder affecting primarily Schwann cells. NT-3 improves axonal degenerative disorders caused by neurotoxins such as pyridoxine and cisplatin. It may exert its therapeutic effects primarily on neuronal perikarya or axons. If this is correct, NT-3 therapy may enhance axonal maintenance and regeneration in CMT1A by substituting for the lack of normal Schwann cell tropic support that results from the excess Schwann cell synthesis of PMP22 in these patients. Alternatively, since Sahenk et al. observed that NT-3 treatment increased the numbers of Schwann cells in both nude mouse CMT1A xenografts and in Trembler-J sciatic nerve segments distal to a crush, the therapeutic effect of NT-3 in CMT1A … [1]: /embed/graphic-1.gif

Both positive and negative factors regulate gene expression following chronic facial nerve resection

Previously, we reported that following a chronic nerve resection, removal of the neuroma reversed the atrophy, increased the number of countable motoneurons and resulted in the re-expression of GAP-43 and α tubulin mRNA. In the present study, we questioned whether this response was due to the removal of the neuroma, or a result of factors such as neurotrophins, produced at the injury site. To test this hypothesis, 10 weeks after axotomy, the axonal transport blocker colchicine or, glial derived neurotrophic factor (GDNF) was injected proximal to the neuroma. The injection of GDNF or colchicine elicited an increase in motoneuron size and in GAP-43, but not α tubulin, mRNA. These data suggest that in addition to factors produced at the injury site, the neuroma acts as a source of target-like repressive signals that when removed results in an increase in gene expression and motoneuron size. To analyze the regenerative potential of chronically resected motoneurons, mice without a previous nerve injury and mice with a chronic resection received a pre-degenerated segment of sciatic nerve attached to the proximal facial nerve stump. Axons from both the chronic and acute groups grew into the grafts, however, significantly more retrogradely labeled motoneurons were counted in the acute group compared to the chronic resection group. No difference in motoneuron cell size was observed between the two groups of regenerated neurons. Therefore, despite severe atrophy, many of the surviving mouse facial motoneurons retain the propensity to extend their axons when provided with the appropriate environment.

The Effects of Exogenous Nitric Oxide Donor on Motor Functional Recovery of Reperfused Peripheral Nerve

To investigate the effects of the nitric oxide donor S-nitroso-N-acetylcysteine (SNAC) on motor functional recovery of reperfused rat sciatic nerve. Seventy-eight rats were divided into groups treated with SNAC (100 nmol/100 g/min), methylprednisolone 30 mg/kg/h for 15 minutes, 45-minute pause, 5.4 mg/kg/h for 1.5 h), and phosphate-buffered saline 0.2 mL/100 g/h). A 1-cm segment of sciatic nerve had 2 hours of ischemia and the results were evaluated after various reperfusion periods using a walking track test, muscle contractile testing, muscle weight, and histology. During reperfusion there was a significant overall improvement in sciatic functional index measurement and isometric titanic contractile force for the SNAC-treated group compared with the methylprednisolone- and phosphate-buffered saline- treated groups. The SNAC group had significantly earlier improvement in the sciatic functional index measurement between days 7 and 28. Restoration of the contractile force and muscle weight of the extensor digitorum longus muscle began earlier in the SNAC group--after day 11--whereas the other 2 groups showed progressive atrophy until day 21, with a significant difference between the SNAC group and the other 2 groups. Histologic examination showed that SNAC-treated rats had less severe degeneration and earlier regeneration of axons than the others. Although methylprednisolone-treated rats showed earlier recovery than phosphate-buffered saline-treated rats in all parameters there were no significant differences between these 2 groups. Supplementation of nitric oxide is effective in promoting motor functional recovery of the reperfused peripheral nerve and has potential to replace or augment steroids as therapeutic agents in treatment of nervous system ischemia/reperfusion injury.

Effect of Unilateral Damage to Sciatic Nerve on Phenotype of Lumbrical Muscles in Experimental and Contralateral Legs in Rats

Expression of slow myosin in fast lumbrical muscle during unilateral damage to the sciatic nerve was studied in rats. Four weeks after unilateral excision of sciatic nerve segment or its crushing, the content of slow fiber in the lumbrical muscle of the contralateral leg tended to increase (detected using monoclonal antibodies against slow myosin). The extrapyramidal system seems to modulate the phenotype of muscle fibers via motoneurons of the spinal cord, while the compensatory activation of this system manifests in pronounced "deceleration" of both the fast and slow muscles in the hind legs.

Peripheral Nerve Allografts Stored in Green Tea Polyphenol Solution

We previously demonstrated the successful 1-month storage of peripheral nerve segments in a green tea polyphenol extract. We investigated whether this method could reduce the donor-host immune reaction associated with peripheral nerve allotransplantation. Sciatic nerve segments (20 mm long) were harvested from Dark Agouti (DA) rats, stored in polyphenol solution (1 mg/mL) for 1 month, and transplanted into recipient major histocompatibility complex-mismatched Lewis rats to bridge 15-mm-long sciatic nerve gaps (polyphenol-treated allograft group). The controls were an isograft group (nerve segments harvested from Lewis rats were immediately transplanted into Lewis rats), a polyphenol-treated isograft group (nerve segments harvested from Lewis rats were treated by polyphenol in the same method and transplanted into Lewis rats), and a fresh allograft group (nerve segments harvested from DA rats were transplanted into Lewis rats without storage). To investigate the origins of the cells in the transplanted nerves, sciatic nerve segments harvested from the male DA rat donors were transplanted into female Lewis rat recipients; genomic DNA was extracted from each nerve segment and amplified by polymerase chain reaction using primers specific for the rat sex-determining region of the Y-chromosome (Sry). Nerve regeneration in the polyphenol-treated allograft group was similar to that in the isografted group. Sry-specific bands were detected in all samples in the sex-mismatched polyphenol-treated allograft specimens despite their major histocompatibility complex incompatibility. Storage in green tea polyphenol solution can reduce both ischemic damage to nerve tissue and donor-host immune reactions after allotransplantation.

Optimal conditions for peripheral nerve storage in green tea polyphenol: an experimental study in animals

Our previous study demonstrated successful peripheral nerve storage for 1 month using polyphenol solution. We here report two studies to solve residual problems in using polyphenols as a storage solution for peripheral nerves. Study 1 was designed to determine the optimal concentration of the polyphenol solution and the optimal immersion period for nerve storage. Rat sciatic nerve segments were immersed in polyphenol solution at three different concentrations (2.5, 1.0, and 0.5 mg/ml) for three different periods (1, 7, and 26 days). Electrophysiological and morphological studies demonstrated that nerve regeneration from nerve segments that had been immersed in 1 mg/ml polyphenol solution for 1 week and in Dulbecco's modified Eagle's medium (DMEM) for the subsequent 3 weeks was superior to the regeneration in other treatment groups. In study 2, the permeability of nerve tissue to polyphenol solution was investigated using canine sciatic nerve segments stored in 1.0 mg/ml polyphenol solution for 1 week and in DMEM for the subsequent 3 weeks. Electron microscopy revealed that the Schwann cell structure within 500–700 μm of the perineurium was preserved, but cells deeper than 500–700 μm were badly damaged or had disappeared. The infiltration limit for polyphenol solution into neural tissue is inferred to be 500–700 μm.

Vimentin-Dependent Spatial Translocation of an Activated MAP Kinase in Injured Nerve

How are phosphorylated kinases transported over long intracellular distances, such as in the case of axon to cell body signaling after nerve injury? Here, we show that the MAP kinases Erk1 and Erk2 are phosphorylated in sciatic nerve axoplasm upon nerve injury, concomitantly with the production of soluble forms of the intermediate filament vimentin by local translation and calpain cleavage in axoplasm. Vimentin binds phosphorylated Erks (pErk), thus linking pErk to the dynein retrograde motor via direct binding of vimentin to importin beta. Injury-induced Elk1 activation and neuronal regeneration are inhibited or delayed in dorsal root ganglion neurons from vimentin null mice, and in rats treated with a MEK inhibitor or with a peptide that prevents pErk-vimentin binding. Thus, soluble vimentin enables spatial translocation of pErk by importins and dynein in lesioned nerve.

Proteomics of the Injured Rat Sciatic Nerve Reveals Protein Expression Dynamics During Regeneration

Using proteomics, we investigated the temporal expression profiles of proteins in rat sciatic nerve after experimental crush. Extracts of sciatic nerves collected at 5, 10, and 35 days after injury were analyzed by two-dimensional gel electrophoresis and quantitative image analysis. Of the approximately 1,500 protein spots resolved on each gel, 121 showed significant regulation during at least one time point. Using cluster analysis, these proteins were grouped into two expression profiles of down-regulation and four of up-regulation. These profiles mainly reflected differences in cellular origins in addition to different functional roles. Mass spectrometric analysis identified 82 proteins pertaining to several functional classes, i.e. acute-phase proteins, antioxidant proteins, and proteins involved in protein synthesis/maturation/degradation, cytoskeletal (re)organization, and in lipid metabolism. Several proteins not previously implicated in nerve regeneration were identified, e.g. translationally controlled tumor protein, annexin A9/31, vitamin D-binding protein, alpha-crystallin B, alpha-synuclein, dimethylargininases, and reticulocalbin. Real-time PCR analysis of selected genes showed which were expressed in the nerve versus the dorsal root ganglion neurons. In conclusion, this study highlights the complexity and temporal aspect of the molecular process underlying nerve regeneration and points to the importance of glial and inflammatory determinants.

Transverse elasticity of rabbit sciatic nerves tested by in vitro compression

The Young's modulus of a rabbit sciatic nerve under stepwise in vitro linear compression test was estimated. Segments of rabbit sciatic nerves were compressed in the transverse direction with a custom‐made parallel compression apparatus. Digital images of the cross‐sectional face were taken simultaneously by using a camera mounted on a microscope. The applied force and the gap between the parallel plates of the compression apparatus were measured. Digitized images of the nerve crosssections were used to construct two‐dimensional models of the nerves. The parallel compression results showed that the mean Young's modulus of rabbit sciatic nerves was 41.6±5.0 kPa. By direct visual inspection and by comparing the finite element model simulation results and experimental data, we may suggest that the large fascicle is the main load‐bearing component while the small fascicle and the loose connective tissues like the epineurium bear less load in the parallel compression process.

Resistance to Disruption and Gapping of Peripheral Nerve Repairs: An In Vitro Biomechanical Assessment of Techniques

One potential cause of suboptimal results after nerve repair is disruption or gapping of the neurorrhaphy in the postoperative period. This study assesses the biomechanical strength of five nerve repair techniques: fibrin glue, simple epineurial sutures, and three other novel neurorrhaphy methods. Fifty rabbit sciatic nerve segments were divided and repaired utilizing one of five different methods, producing five groups of ten specimens. Fibrin glue and four epineurial suture techniques (simple, horizontal mattress, "Tajima," "Bunnell") were employed. Repaired nerve segments were ramp-loaded to failure on an Instron 8300 materials-testing machine at a displacement rate of 5 mm/min. Gapping at the repair site was captured using high-resolution video. Differences among the five groups were assessed for significance using ANOVA and Fisher's protected least squares differences post-hoc testing. The mean force to produce disruption was higher for mattress suture repairs relative to simple repairs, but not significantly so (p = 0.31). Both were significantly stronger than fibrin glue repairs (p < 0.0001). "Tajima" and "Bunnell" repairs were both statistically stronger than glue (p < 0.0001), simple (p < 0.0001), or mattress (p = 0.0004) repairs, but not significantly different from one another (p = 0.48). Data for gapping at the repair site were similar with all suture techniques outperforming fibrin glue (p = 0.003). "Bunnell" repairs demonstrated the most resistance to gapping, compared to glue (p < 0.0001), simple (p = 0.0001), mattress (p = 0.007) and "Tajima" repairs (p = 0.01). These data demonstrate that repairs done utilizing fibrin glue are significantly weaker than all types of suture repairs. Two novel techniques for nerve repair (epineurial "Tajima" and "Bunnell") are significantly more resistant to disruption and gapping. Further evaluation to assess the effect of these repair techniques on function is required.

The role of MAP kinases in rapid gene induction after lesioning of the rat sciatic nerve.

Lesion of the sciatic nerve caused a rapid activation of p38MAP kinase in the injured nerve adjacent to the site of transection. This activation was detectable 3 min after lesioning, increased during the next 15 min and remained high for several hours. Erk1/2 activation was also observed as early as 15 min after lesioning. Activation of these MAP kinases was seen in both the external sheaths and the endoneurium. The separation of the external sheaths from the endoneurium accelerated the p38MAP kinase activation. To evaluate whether the injury-activated MAP kinase cascades are implicated in the rapid gene induction observed after nerve lesion, experiments were performed with an ex vivo model. Segments of sciatic nerves were incubated in oxygenated Krebs-Ringer buffer. MAP kinases were activated at 15 min and remained active after 6 h. Induction of mRNA was also observed for nerve growth factor (NGF), interleukin 6 (IL-6), leukaemia inhibitory factor (LIF) and deiodinases of type 2 (D2) and type 3 (D3). Thus, the ex vivo model mimics events occurring in the animal after nerve section. Finally, nerve segments were incubated in the presence of specific inhibitors of Erk1/2 activation (U0126) and of p38MAP kinase activity (SB203580). U0126 inhibited D3, LIF and to a lesser extent NGF mRNA induction, but did not affect significantly the induction of D2 and IL-6 mRNAs. SB203580 inhibited the expression of the genes for D3 and LIF. We conclude that MAP kinase cascades, activated by nerve transection, are involved in the rapid gene induction in the nerve.

Changes in expression of PACAP in rat sensory neurons in response to sciatic nerve compression.

In the present study, expression of pituitary adenylate cyclase-activating polypeptide (PACAP) in rat dorsal root ganglion (DRG) neurons and sciatic nerve following experimental sciatic nerve compression was studied with the use of quantitative immunohistochemistry and in situ hybridization. Previously, we have investigated changes in PACAP expression after nerve transection and, here, the far more frequently encountered condition of nerve compression injury is examined. Nerve compression was performed unilaterally on the rat sciatic nerve, at mid-thigh level, by application of a narrow silicone tube around the nerve for 3, 7, 14 or 28 days, respectively. We detect a statistically significant upregulation in the number and density of PACAP mRNA expression in both small and large DRG neurons in response to nerve compression. An increased number of PACAP-immunoreactive neurons is also found in the ipsilateral DRG. In addition, PACAP immunoreactivity is observed in the compressed sciatic nerve segment and adjacent nerve tissue after nerve compression. The present findings can be compared with previous studies where we have shown that PACAP expression is upregulated in DRG; in response to peripheral inflammation (primarily in small-medium neurons), and after axotomy (dramatic upregulation in medium-large neurons). In view of the recent findings of an increased PACAP expression in DRG after nerve compression, as well as the previous findings of a modulation of PACAP expression in response to axotomy and inflammation, it is likely that PACAP is also involved in the modulation of the response to peripheral nerve compression.

Successful storage of peripheral nerve before transplantation using green tea polyphenol: an experimental study in rats

Green tea polyphenol is known to act as a buffer, reducing biological responses to oxidative stress. Several effects of polyphenol have been reported, such as protection of tissue from ischemia, antineoplasmic and anti-inflammatory effects, and suppression of arteriosclerosis. In this study, we investigated whether peripheral nerve segments could be kept viable in a polyphenol solution for 1 month. Sciatic nerve segments, 20 mm long, were harvested from Lewis rats and treated in three different ways before transplanting to recipient Lewis rats to bridge sciatic nerve gaps created by removal of 15-mm-long nerve segments. Group F: nerve segments were transplanted immediately after harvesting. Group P: nerve segments were transplanted after they had been stored in Dulbecco's Modified Eagle's Medium (DMEM) containing polyphenol for 7 days at 4°C and then in DMEM for 21 days at 4°C. Group M: nerve segments were stored in DMEM solution alone for 28 days at 4°C. Viability of the nerve segments was assessed by vital staining (calcein-AM/ethidium homodimer), by electron microscopy and by genomic studies before transplantation. Nerve regeneration was evaluated using electrophysiological and morphological studies 12 and 24 weeks after transplantation. Neural cell viability of the preserved nerve segments was confirmed in group P, in which the nerve regeneration was similar to that in group F and superior to that in group M. Peripheral nerve segments can be successfully preserved for 1 month using green tea polyphenol.