Number Of Myelinated Nerve Fibers Research Articles

Role of shortwave and microwave diathermy in peripheral neuropathy.

ObjectiveThis study was performed to review the current evidence for the efficacy of shortwave and microwave diathermy in promoting nerve regeneration after peripheral nerve injuries in both animal models and human patients.MethodsAn extensive literature search was conducted without publication data restrictions. Studies including the intervention and outcome in animal or human models were selected. Non-English studies, reviews, letters, and case reports were excluded.ResultsEleven articles were included in this study. Shortwave diathermy at the frequency of 27.12 or 40.68 MHz was used in six of seven animal studies, while only one study utilized microwave diathermy at 915 MHz. Seven animal experiments demonstrated that shortwave or microwave diathermy produces an increased myelinated nerve fiber number, myelin sheath thickness, and axon diameter as well as improved electrophysiological parameters and locomotion. A total of 128 patients (207 wrists) were enrolled in four clinical studies. The clinical use of diathermy in human patients with carpal tunnel syndrome showed positive effects on pain, hand function, and electrophysiological findings.ConclusionsShortwave or microwave diathermy can improve the electrophysiological parameters, myelinated fiber number, and axon diameter of the injured nerve.

Aging of bovine spinal cord: an alteration of myelinated nerve fibers in the white matter

To gain more knowledge of age-related changes in the spinal cord of the bovine species, the structure of 15 clinically normal aged cattle (Holstein-Friesian cows 8–13 years of age) was histopathologically examined. In 12 (80%) of the 15 animals, the common histopathological features identified were alteration of a small number of myelinated nerve fibers in the white matter, with less than 4 nerve fibers affected per cross-sectional area of the spinal cord. Alteration of nerve fibers was characterized by dilation of myelin sheaths with loss of axons or macrophage infiltration, resembling features of Wallerian axonal degeneration. The occurrence of this nerve fiber alteration had a predilection for the lateral and ventral white matter funiculi. In eight cattle, so-called axonal spheroids were rarely present in the white matter. There was little evidence of glial reaction against nerve fiber alteration. Gray horn neurons were unremarkable. Lipofuscin granules were recognized in neurons, glial cells, and neuropil of the medulla oblongata examined in six cows. The changes observed in the spinal cord white matter of the present cows were similar to those described previously in aged human beings and domestic and laboratory animals, and thus were likely to have been a phenomenon which was closely related to aging. The strict clinical significance of the histopathological changes in the spinal cord white matter remains undetermined.

The combined effect of mesenchymal stem cells and resveratrol on type 1 diabetic neuropathy.

Diabetic neuropathy (DN) is one of the most common diabetic complications that results in an increase in patient discomfort and pain. The present study demonstrated that mesenchymal stem cells (MSCs) or resveratrol (RSV) may improve diabetic hyperglycemia and neuropathy. The aim of the present study was to investigate the combined effect of MSCs and RSV on DN. A total of 100 non-obese diabetic mice were divided into the following six groups: Normal control, MSCs, RSV, MSCs + RSV, insulin and diabetic control groups. Following homologous therapy, the levels of blood glucose and C-peptide, islets, nuclear factor (NF)-κB, nerve growth factor (NGF) and myelin basic protein (MBP), and the sciatic nerve structure in each group were examined and evaluated. Following the administration of therapy, the levels of blood glucose and C-peptide in mice in the MSCs + RSV group were significantly improved when compared with the other diabetic groups, and the dosage of insulin therapy required was the lowest among the six experimental groups (P<0.05). The levels of NGF, MBP and NF-κB in the MSCs + RSV group were significantly improved compared with the MSCs and RSV groups (P<0.05). Furthermore, the diameter of the axon, number of myelinated nerve fibers and the depth of the myelin sheath in the MSCs + RSV group were greatest among the five examined groups (excluding the control). The combination of RSV and MSCs could relieve hyperglycemia and improve DN. This indicated that the combination of RSV and MSCs may be a novel therapeutic method for the treatment of DN.

Reinnervation of spinal cord anterior horn cells after median nerve repair using transposition with other nerves.

Our previous studies have confirmed that during nerve transposition repair to injured peripheral nerves, the regenerated nerve fibers of motor neurons in the anterior horn of the spinal cord can effectively repair distal nerve and target muscle tissue and restore muscle motor function. To observe the effect of nerve regeneration and motor function recovery after several types of nerve transposition for median nerve defect (2 mm), 30 Sprague-Dawley rats were randomly divided into sham operation group, epineurial neurorrhaphy group, musculocutaneous nerve transposition group, medial pectoral nerve transposition group, and radial nerve muscular branch transposition group. Three months after nerve repair, the wrist flexion test was used to evaluate the recovery of wrist flexion after regeneration of median nerve in the affected limbs of rats. The number of myelinated nerve fibers, the thickness of myelin sheath, the diameter of axons and the cross-sectional area of axons in the proximal and distal segments of the repaired nerves were measured by osmic acid staining. The ratio of newly produced distal myelinated nerve fibers to the number of proximal myelinated nerve fibers was calculated. Wet weights of the flexor digitorum superficialis muscles were measured. Muscle fiber morphology was detected using hematoxylin-eosin staining. The cross-sectional area of muscle fibers was calculated to assess the recovery of muscles. Results showed that wrist flexion function was restored, and the nerve grew into the distal effector in all three nerve transposition groups and the epineurial neurorrhaphy group. There were differences in the number of myelinated nerve fibers in each group. The magnification of proximal to distal nerves was 1.80, 3.00, 2.50, and 3.12 in epineurial neurorrhaphy group, musculocutaneous nerve transposition group, medial pectoral nerve transposition group, and radial nerve muscular branch transposition group, respectively. Nevertheless, axon diameters of new nerve fibers, cross-sectional areas of axons, thicknesses of myelin sheath, wet weights of flexor digitorum superficialis muscle and cross-sectional areas of muscle fibers of all three groups of donor nerves from different anterior horn motor neurons after nerve transposition were similar to those in the epineurial neurorrhaphy group. Our findings indicate that donor nerve translocation from different anterior horn motor neurons can effectively repair the target organs innervated by the median nerve. The corresponding spinal anterior horn motor neurons obtain functional reinnervation and achieve some degree of motor function in the affected limbs.

Olfactory ensheathing cells promote nerve regeneration and functional recovery after facial nerve defects.

Olfactory ensheathing cells from the olfactory bulb and olfactory mucosa have been found to increase axonal sprouting and pathfinding and promote the recovery of vibrissae motor performance in facial nerve transection injured rats. However, it is not yet clear whether olfactory ensheathing cells promote the reparation of facial nerve defects in rats. In this study, a collagen sponge and silicone tube neural conduit was implanted into the 6-mm defect of the buccal branch of the facial nerve in adult rats. Olfactory ensheathing cells isolated from the olfactory bulb of newborn Sprague-Dawley rats were injected into the neural conduits connecting the ends of the broken nerves, the morphology and function of the regenerated nerves were compared between the rats implanted with olfactory ensheathing cells with the rats injected with saline. Facial paralysis was assessed. Nerve electrography was used to measure facial nerve-induced action potentials. Visual inspection, anatomical microscopy and hematoxylin-eosin staining were used to assess the histomorphology around the transplanted neural conduit and the morphology of the regenerated nerve. Using fluorogold retrograde tracing, toluidine blue staining and lead uranyl acetate staining, we also measured the number of neurons in the anterior exterior lateral facial nerve motor nucleus, the number of myelinated nerve fibers, and nerve fiber diameter and myelin sheath thickness, respectively. After surgery, olfactory ensheathing cells decreased facial paralysis and the latency of the facial nerve-induced action potentials. There were no differences in the general morphology of the regenerating nerves between the rats implanted with olfactory ensheathing cells and the rats injected with saline. Between-group results showed that olfactory ensheathing cell treatment increased the number of regenerated neurons, improved nerve fiber morphology, and increased the number of myelinated nerve fibers, nerve fiber diameter, and myelin sheath thickness. In conclusion, implantation of olfactory ensheathing cells can promote regeneration and functional recovery after facial nerve damage in rats.

Simvastatin vs. L-Carnitine: An experimental study on optimizing nerve repair.

Complicity and slow rate of axons regeneration necessitates microsurgery that adjuvant therapy can help it. Improving nerve metabolic capacity and response to neural growth factors are positive effects of simvastatin and L-carnitine. To decrease neuronal loss after axotomy and improve neuronal regeneration, this study was designed to assay effects of these agents on nerve repair. Left sciatic nerve of 70 female rats were cut and repaired under aseptic microsurgery. Based on medications and treatment period, seven groups were formed. no medication. SIM1W: one week daily oral simvastatin. LC1W: one week daily oral L-carnitine. Plb1W: one week daily oral placebo. SIM1M: one month daily oral simvastatin. LC1M: one month daily oral L-carnitine. Plb1M: one month daily oral placebo. Following 90 days, behavioral assessments and then histopathology were done. Mean reflex time of withdrawal reflex latency and toe out angle in all experimented groups increased than normal. Long-term drug-medication significantly improved toe out angle. In long-term drug-medication, inflammation and neural bundle differentiation were significantly lower and higher, respectively. Vascular index showed reduction but number of myelinated nerve fibers had rises in drug-medicated groups compared to control and placebo groups. No obvious differences were detected in myeline diameter. Both Simvastatin and L-carnitine can accelerate and improve the process of nerve regeneration in a long enough treatment period. The regulatory influence of these exogenous neurotrophic drugs may be essential to optimize regeneration of nerve fibers; so can broaden horizons for novel therapeutic modalities to decrease neuronal apoptosis.

Functional evaluation outcomes correlate with histomorphometric changes in the rat sciatic nerve crush injury model: A comparison between sciatic functional index and kinematic analysis.

Elucidating whether there is a correlation between biomechanical functions and histomorphometric data in the rat sciatic nerve crush injury model would contribute to an accurate evaluation of the regeneration state without sacrificing animals. The gold standard for functional evaluation is the sciatic functional index (SFI) despite there being intrinsic shortcomings. Kinematic analysis is considered a reliable and sensitive approach for functional evaluation, most commonly assessed as ankle angle at various phases of a gait cycle. Studies utilizing the toe angle for functional evaluation are scarce, and changes in the toe angle following surgery remain unknown. The present study assessed correlations of ankle angle, toe angle and SFI with histomorphometric data, aiming to determine which parameters most accurately reflect changes in histomorphometric data over time. Six Lewis rats were designated as the control group. 30 animals received surgery, six of them were randomly selected on the first, second, third, fourth, and sixth week after surgery for measurements of ankle and toe angles in the “toe-off” phase, and for evaluation of SFI. Histomorphometric analysis were also performed, to determine the number of myelinated nerve fibers, diameters of myelinated nerve fibers, axon diameters, and myelin sheath thicknesses. Furthermore, we investigated changes in ankle angle, toe angle, SFI, and histomorphometric data over time, as well as correlations between ankle angle, toe angle, and SFI with histomorphometric data. The results revealed that changes in SFI, ankle angle, and toe angle highly correlate with histomorphometric data in the rat sciatic nerve crush injury model. Toe angle reflected changes in histomorphometric data with time more precisely than ankle angle or SFI did, and ankle angle was a better prognostic parameter than SFI.

A basic fibroblast growth factor slow‐release system combined to a biodegradable nerve conduit improves endothelial cell and Schwann cell proliferation: A preliminary study in a rat model

A basic fibroblast growth factor (bFGF) slow-release system was combined to a biodegradable nerve conduit with the hypothesis this slow-release system would increase the capacity to promote nerve vascularization and Schwann cell proliferation in a rat model. Slow-release of bFGF was determined using Enzyme-Linked ImmunoSorbent Assay (ELISA). A total of 60 rats were used to create a 10 mm gap in the sciatic nerve. A polyglycolic acid-based nerve conduit was used to bridge the gap, either without or with a bFGF slow-release incorporated around the conduit (n = 30 in each group). At 2 (n = 6), 4 (n = 6), 8 (n = 6), and 20 (n = 12) weeks after surgery, samples were resected and subjected to histological, immunohistochemical, and transmission electron microscopic evaluation for nerve regeneration. Continuous release of bFGF was found during the observation period of 2 weeks. After in vivo implantation of the nerve conduit, greater endothelial cell migration and vascularization resulted at 2 weeks (proximal: 20.0 ± 2.0 vs. 12.7 ± 2.1, P = .01, middle: 17.3 ± 3.5 vs. 8.7 ± 3.2, P = .03). Schwann cells showed a trend toward greater proliferation and axonal growth had significant elongation (4.9 ± 1.1 mm vs. 2.8 ± 1.5 mm, P = .04) at 4 weeks after implantation. The number of myelinated nerve fibers, indicating nerve maturation, were increased 20 weeks after implantation (proximal: 83.3 ± 7.5 vs. 53.3 ± 5.5, P = .06, distal: 71.0 ± 12.5 vs. 44.0 ± 11.1, P = .04). These findings suggest that the bFGF slow-release system improves nerve vascularization and Schwann cell proliferation through the biodegradable nerve conduit.

Research of acellular xenogeneic nerve combined with adipose-derived stem cells and platelet rich plasma in repair of rabbit facial nerve injury

To investigate the early effects of acellular xenogeneic nerve combined with adipose-derived stem cells (ADSCs) and platelet rich plasma (PRP) in repairing facial nerve injury in rabbits. The bilateral sciatic nerves of 15 3-month-old male Sprague-Dawley rats were harvested and decellularized as xenografts. The allogeneic ADSCs were extracted from the neck and back fat pad of healthy adult New Zealand rabbits with a method of digestion by collagenase type Ⅰ and the autologous PRP was prepared by two step centrifugation. The 3rd generation ADSCs with good growth were labelled with CM-Dil living cell stain, and the labelling and fluorescence attenuation of the cells were observed by fluorescence microscope. Another 32 New Zealand rabbits were randomly divided into 4 groups and established the left facial nerve defect in length of 1 cm ( n=8). The nerve defects of groups A, B, C, and D were repaired with CM-Dil-ADSCs composite xenogeneic nerve+autologous PRP, CM-Dil-ADSCs composite xenogeneic nerve, xenogeneic nerve, and autologous nerve, respectively. At 1 and 8 weeks after operation, the angle between the upper lip and the median line of the face (angle θ) was measured. At 4 and 8 weeks after operation, the nerve conduction velocity was recorded by electrophysiological examination. At 8 weeks after operation, the CM-Dil-ADSCs at the distal and proximal ends of regenerative nerve graft segment in groups A and B were observed by fluorescence microscopy; after toluidine blue staining, the number of myelinated nerve fibers in regenerated nerve was calculated; the structure of regenerated nerve fibers was observed by transmission electron microscope. ADSCs labelled by CM-Dil showed that the labelling rate of cells was more than 90% under fluorescence microscope, and the labelled cells proliferated well, and the fluorescence attenuated slightly after passage. All the animals survived after operation, the incision healed well and no infection occurred. At 1 week after operation, all the animals in each group had different degrees of dysfunction. The angle θ of the left side in groups A, B, C, and D were (53.4±2.5), (54.0±2.6), (53.7±2.4), and (53.0±2.1)°, respectively; showing significant differences when compared with the healthy sides ( P<0.05). At 8 weeks after operation, the angle θ of the left side in groups A, B, C, and D were (61.9±4.7), (56.8±4.2), (54.6±3.8), and (63.8±5.8)°, respectively; showing significant differences when compared with the healthy sides and with the values at 1 week ( P<0.05). Gross observation showed that the integrity and continuity of regenerated nerve in 4 groups were good, and no neuroma and obvious enlargement was found. At 4 and 8 weeks after operation, the electrophysiological examination results showed that the nerve conduction velocity was significantly faster in groups A and D than in groups B and C ( P<0.05), and in group B than in group C ( P<0.05); no significant difference was found between groups A and D ( P>0.05). At 8 weeks after operation, the fluorescence microscopy observation showed a large number of CM-Dil-ADSCs passing through the distal and proximal transplants in group A, and relatively few cells passing in group B. Toluidine blue staining showed that the density of myelinated nerve fibers in groups A and D were significantly higher than those in groups B and C ( P<0.05), and in group B than in group C ( P<0.05); no significant difference was found between groups A and D ( P>0.05). Transmission electron microscope observation showed that the myelinated nerve sheath in group D was large in diameter and thickness in wall. The morphology of myelin sheath in group A was irregular and smaller than that in group D, and there was no significant difference between groups B and C. ADSCs can survive as a seed cell in vivo, and can be differentiated into Schwann-like cells under PRP induction. It can achieve better results when combined with acellular xenogeneic nerve to repair peripheral nerve injury in rabbits.

The total number of myelinated nerve fibers is reduced in corpus callosum in brains from patients with Alzheimer's disease.

The total number of myelinated fibers in corpus callosum (CC) in Alzheimer's disease is poorly described. Using a two-dimensional fractionator principle we estimated the total number of fibers in ten females patients with Alzheimer's disease (AD) (mean age 82.8years) and 12 female control subjects (mean age 80.6years) and found the mean number of myelinated fibers to be significantly 30% higher in the control group (90.0× 106; coefficient of variation= SD/mean= 27%) than in the AD group (69.3× 106; coefficient of variation= 20%) (p= 0.028). A significant loss of fibers (≥2.2μm in diameter) was found in the anterior part of the CC in AD patients compared to control subjects (p= 0.045). For both groups, we found a positive correlation between the total number of myelinated fibers and CC cross-sectional area (AD, r= 0.81; control subjects, r= 0.73). There was a negative correlation in both groups between age and total number of myelinated fibers (AD, r=-0.81; controls subjects, r=-0.59). These results implicate a loss of intrahemispheric connections in the pathophysiology of AD.

Expression patterns and role of PTEN in rat peripheral nerve development and injury

Studies have suggested that phosphatase and tensin homolog (PTEN) plays an important role in neuroprotection and neuronal regeneration. To better understand the potential role of PTEN with respect to peripheral nerve development and injury, we investigated the expression pattern of PTEN at different stages of rat peripheral nerve development and injury and subsequently assessed the effect of pharmacological inhibition of PTEN using bpV(pic) on axonal regeneration in a rat sciatic nerve crush injury model. During the early stages of development, PTEN exhibits low expression in neuronal cell bodies and axons. From embryonic day (E) 18.5 and postnatal day (P)5 to adult, PTEN protein becomes more detectable, with high expression in the dorsal root ganglia (DRG) and axons. PTEN expression is inhibited in peripheral nerves, preceding myelination during neuronal development and remyelination after acute nerve injury. Low PTEN expression after nerve injury promotes Akt/mammalian target of rapamycin (mTOR) signaling pathway activity. In vivo pharmacological inhibition of PTEN using bpV(pic) promoted axonal regrowth, increased the number of myelinated nerve fibers, improved locomotive recovery and enhanced the amplitude response and nerve conduction velocity following stimulation in a rat sciatic nerve crush injury model. Thus, we suggest that PTEN may play potential roles in peripheral nerve development and regeneration and that inhibition of PTEN expression is beneficial for nerve regeneration and functional recovery after peripheral nerve injury.

Negative Pressure Therapy in the Regeneration of the Sciatic Nerve Using Vacuum - Assisted Closure in a Rabbit Model.

BackgroundThe aim of this study was to investigate the effects of negative pressure therapy in the regeneration of the rabbit sciatic nerve using vacuum assisted closure (VAC).Material/MethodsThirty male New Zealand white rabbits underwent surgical injury of the sciatic nerve, followed by negative pressure therapy using vacuum assisted closure (VAC), in three treatment groups: Group A: 0 kPa; Group B: −20 kPa; Group C: −40 kPa. At 12 weeks following surgery, the following factors were studied: motor nerve conduction velocity (MNCV); the number of myelinated nerve fibers; the wet weight of the gastrocnemius muscle. Gastrocnemius muscle and sciatic nerve tissue samples were studied for the expression of S100, and brain-derived neurotrophic factor (BDNF) using Western blot.ResultsAt 12 weeks following VAC treatment, the MNCV, number of myelinated nerve fibers, and wet weight of the gastrocnemius muscle showed significant differences between the groups (p<0.05), in the following order: Group B >Group A >Group C. The sciatic nerve at 12 weeks following VAC in Group B and Group C showed a significant increase in expression of S100 and BDNF when compared with Group A; no significant differences were detected between Group B and Group C results from Western blot at 12 weeks.ConclusionsThe findings of this study, using negative pressure therapy in VAC in a rabbit model of sciatic nerve damage, have shown that moderate negative pressure was beneficial, but high values did not benefit sciatic nerve repair.

A morphological and biochemical evaluation of the effects of quercetin on experimental sciatic nerve damage in rats.

The present study evaluated the neuroprotective and antioxidant effects of quercetin in a rat model of sciatic nerve crush injury using histopathological, morphometric and biochemical methods. A total of 48 male Sprague Dawley rats, aged 10–12 weeks old were randomly divided into eight groups, consisting of two sham groups (S-7, S-28), three quercetin-treated groups (Q-7, Q-28; 200 mg/kg/7 days), trauma (T-7, T-28; 1 min sciatic nerve crush injury) and three trauma+quercetin groups (T+Q-7, T+Q-28; trauma+quercetin 200 mg/kg/7 days). Rats were sacrificed on day 7 or 28. Oxidant-antioxidant biochemical parameters in nerve tissues from all groups were analyzed using histopathological staining with toluidine blue and Masson's trichrome. DNA fragmentations were identified using terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling in cells from each tissue sample. Degeneration of the axons and myelin sheath, the breakdown of the concentric lamellar structure of the myelin sheath and axonal swelling were observed in groups T-7 and T-28. Myelin sheath thicknesses, nerve fiber diameters and the number of myelinated nerve fibers decreased, while the apoptotic index (AI) increased in the T-7 and T-28 groups. However, it was observed that nerve regeneration began in the T+Q-7 and T+Q-28 groups compared with the sham groups, together with the healing of cellular damage and axonal structure and a decrease in the AI. Malondialdehyde and superoxide dismutase activity did not differ significantly between the T-7 and S-7 groups. However, catalase activity significantly decreased in the T-28 group when compared with the sham 7 day group. Tissue malondialdehyde levels significantly increased, while serum catalase activity increased in the T+Q-7 group compared with the T-7 group. These results suggest that quercetin has beneficial effects on nerve regeneration and may shorten the healing period in crush-type sciatic nerve injuries.

Chitosan conduit combined with hyaluronic acid prevent sciatic nerve scar in a rat model of peripheral nerve crush injury.

In the present study, the effects of hyaluronic acid (HA) combined with chitosan conduit on peripheral nerve scarring and regeneration were investigated in a rat model of peripheral nerve crush injury. A total of 60 Sprague-Dawley rats were randomly distributed into four groups (15 rats in each group), in which the nerve was either not treated (control group) or treated with chitosan conduit, hyaluronic acid, or chitosan conduit coupled with hyaluronic acid following clamp injury to the sciatic nerve. The surgical sites were evaluated by assessing the sciatic functional index, the degree of scar adhesions, the numbers of myelinated nerve fibers, the average diameter of myelinated nerve fibers and the myelin sheath thickness. Larger epineurial scar thickness was observed in the control groups compared with the treatment groups at 4, 8 and 12 weeks following surgery. There was no significant difference in scar adhesion among the four groups at 4 weeks following surgery. However, animals receiving chitosan coupled with HA demonstrated better neural recovery, as measured by reduced nerve adherence to surrounding tissues, less scar adhesion, increased number of axons, nerve fiber diameter and myelin thickness. In conclusion, the application of chitosan conduit combined with HA, to a certain extent, inhibited sciatic nerve extraneural scaring and adhesion, and promoted neural regeneration and recovery.

Total brachial plexus injury: contralateral C7 root transfer to the lower trunk versus the median nerve.

Contralateral C7 (cC7) root transfer to the healthy side is the main method for the treatment of brachial plexus root injury. A relatively new modification of this method involves cC7 root transfer to the lower trunk via the prespinal route. In the current study, we examined the effectiveness of this method using electrophysiological and histological analyses. To this end, we used a rat model of total brachial plexus injury, and cC7 root transfer was performed to either the lower trunk via the prespinal route or the median nerve via a subcutaneous tunnel to repair the injury. At 4, 8 and 12 weeks, the grasping test was used to measure the changes in grasp strength of the injured forepaw. Electrophysiological changes were examined in the flexor digitorum superficialis muscle. The change in the wet weight of the forearm flexor was also measured. Atrophy of the flexor digitorum superficialis muscle was assessed by hematoxylin-eosin staining. Toluidine blue staining was used to count the number of myelinated nerve fibers in the injured nerves. Compared with the traditional method, cC7 root transfer to the lower trunk via the prespinal route increased grasp strength of the injured forepaw, increased the compound muscle action potential maximum amplitude, shortened latency, substantially restored tetanic contraction of the forearm flexor muscles, increased the wet weight of the muscle, reduced atrophy of the flexor digitorum superficialis muscle, and increased the number of myelinated nerve fibers. These findings demonstrate that for finger flexion functional recovery in rats with total brachial plexus injury, transfer of the cC7 root to the lower trunk via the prespinal route is more effective than transfer to the median nerve via subcutaneous tunnel.

P53-Mediated oligodendrocyte apoptosis initiates demyelination after compressed spinal cord injury by enhancing ER-mitochondria interaction and E2F1 expression

Oligodendrocyte apoptosis mediated demyelination is a pathological change characteristic of compressed spinal cord injury (CSCI). However, the mechanism of demyelination due to oligodendrocyte apoptosis is not known. In this study, after successfully establishing a rat CSCI model using a custom-made compressor, we investigated the pathological changes, MBP expression, as well as apoptosis-related protein (p53, active caspase-3) expression to determine whether or not apoptosis and demyelination occurred after injury. To understand the possible mechanism of oligodendrocyte apoptosis, caspase-12 and cytochrome C were analyzed to explore the relationship between oligodendrocyte apoptosis and endoplasmic reticulum(ER)-mitochondria interaction. The transcription factor, E2F1, was also detected by immunofluorescence and Western blot assays. The results showed that CSCI increased the expression levels of p53, E2F1 and active caspase-3 followed by the swelling and breakdown of myelin sheaths. The number of myelinated nerve fibers also decreased with down-regulated expression of MBP. Expression levels of caspase-12 and cytochrome C were enhanced along with a reduction in the number of oligodendrocytes. After treatment of CSCI in rats with Pifithrin-μ(PFT-μ), a specific inhibitor of p53, pathomorphological changes of myelin sheath improved significantly. Expression levels of E2F1, active caspase-3, caspase-12 and cytochrome C were down-regulated, consistent with reduced the number of apoptotic oligodendrocytes. These results demonstrated that over-expression of p53 could mediate oligodendrocyte apoptosis thus resulting in demyelination in two ways; by enhancing ER-mitochondria interaction and by triggering the E2F1 mediated apoptosis pathway.

Changes of endogenous Spastin expression after sciatic nerve injury in rats

To investigate the expression change of endogenous Spastin after sciatic nerve injury in rats, and to discuss the role and significance in the peripheral nerve regeneration. Thirty-six adult male Sprague Dawley rats weighing 180-220 g were randomly divided into the experimental group ( n=30) and the control group ( n=6). Sciatic nerve compression damage model was established in the experimental group, and the sciatic nerve was only exposed in the control group. The L 4-6 spinal cord tissue was obtained to detect Spastin mRNA and protein levels by real-time fluorescence quantitative PCR and Western blot at 1, 3, 7, 14, and 28 days after operation in the experimental group ( n=6) and at 7 days in the control group. Meanwhile, the sciatic nerve at 5 mm distal to the injured site was obtained to observe the ultrastructure of the distal axon by transmission electron microscope (TEM). The expression trends of Spastin gene and Spastin protein in L 4-6 spinal cord tissue of 2 groups were basically identical. In the experimental group, the expressions of Spastin gene and protein decreased at the beginning, and then increased; the expressions reduced to the minimum at 7 days after operation, and came back to the initial level at 28 days. The expression levels of Spastin mRNA and protein at 3, 7, and 14 days were significantly lower in the experimental group than the control group ( P<0.05), but no significant difference was noted between 2 groups at 1 and 28 days ( P>0.05). The expression levels of Spastin mRNA and protein at 3, 7, and 14 days were significantly lower than those at 1 and 28 days in the experimental group ( P<0.05), but no significant difference was noted between at 1 day and 28 days ( P>0.05). At 1, 3, and 7 days after operation, the myelin damage was observed by TEM; at 14 days, there were regenerating Schwann cells; at 28 days, a large number of myelinated nerve fibers were seen, which were closed to normal form. In the process of sciatic nerve regeneration after injury, a complex succession of changes take place in the expression of endogenous Spastin protein in rats, indicating that Spastin protein plays an important role in the process.

Decellularized nerve xenograft combined with lycium barbarum polysaccharide for repair of sciatic nerve defect in rats

Objective To explore the effect of lycium barbarum polysaccharide (LBP) and decellularized nerve xenograft combination on nerve regeneration and recovery in repairing rat sciatic nerve defects. Methods Xenogeneic acellular nerve scaffolds were prepared by chemical extraction of tibial nerves from rabbits. A 10 mm left sciatic nerve defect model was created in 90 healthy adult Sprague-Dawley rats who were randomly divided into 5 groups: blank group (n=18), model group (n=18), LBP group (n=18), scaffold group (n=18), LBP and scaffold combination group (n=18). Two weeks after model creation. The sciatic nerve defect in LBP, scaffold and combination groups was repaired either by LBP, by scaffold, or by the LBP xenograft combination. After the second surgery, the rats survived for 4, 8 and 12 weeks, respectively. Gross observation of the scaffold, nerve conduction study to measure sciatic nerve motor nerve conduction velocity (MNCV), and neuromorphometry analysis of the graft were carried out at these three time points. Results Neuroma formation at the proximal nerve end was observed in the model group and LBP group. Adhesion of nerve ends to the surrounding tissue was more severe in the model group than in the LBP group. The sizes of the nerve grafts in the scaffold group and combination group were comparable. Proficient vascularization on the surface of these grafts was seen. There was only slight adhesion to the surrounding tissue. The regenerated nerve fibers in the combination group were denser and better oriented. Motor nerve conduction velocity recovery and the number of myelinated nerve fibers in the grafts were measured at 12 weeks postoperatively for blank, model, LBP, scaffold and combination groups, respectively. The differences among the groups were significant (P<0.05). Conclusion The combination of LBP and xenogeneic acellular nerve scaffold enhances peripheral nerve regeneration and recovery when used to repair nerve defects. Key words: Sciatic nerve; Nerve regeneration; Xenogeneic acellular nerve scaffold; Lycium barbarum polysaccharide

The Effect of Short Nerve Grafts in Series on Axonal Regeneration Across Isografts or Acellular Nerve Allografts

To evaluate the regenerative effect of the additional suture line when using either isografts (ISOs) or acellular nerve allografts (ANAs) placed end-to-end to span a short gap in a rat model. Rat sciatic nerves were transected and repaired with 2-cm nerve grafts (ISO or ANA). The grafts were 2 cm in length or a 1-cm segment was connected end-to-end to a 1-cm segment to yield a 2-cm length. At 8 weeks, extensor digitorum longus (EDL) muscle force and mass were measured. Nerves were harvested for histomorphometry. In a separate parallel study, the nerves were harvested 2 weeks following graft implantation to assess gene expression changes. All grafts demonstrated regeneration across the 2-cm segment(s). The additional suture line did not result in statistical differences in the number of myelinated nerve fibers that reached the distal nerve. However, when the graft types were compared, there was a significant decrease in nerve fibers in the ANA groups. The EDL muscle mass was significantly greater by using nerve ISOs compared with ANAs, regardless of an additional suture line, but there were no statistical differences noted in EDL muscle force. Gene expression analysis did not differ owing to an additional suture line. Minimal axonal loss and no functional deficits were identified with an additional suture line in this rodent short nerve gap model. Placing nerve grafts in series is a viable option for treating short nerve gaps; however, the use of autografts remains preferable over the use of ANAs.

Combination of small gap suture with nerve fragments in the experimental study of the rat nerve defects

Objective: To study the effect of nerve fragments and small gap suture of epineurium in peripheral nerve repair. Methods: (1) The experimental animals were randomly divided into control group, simple small gap suture group, small gap suture combined neural debris group; (2) observing the nerve anastomosis after two weeks; (3) testing nerve fiber regeneration after eight weeks; (4) testing gastrocnemius wet weight ratio after eight weeks; (5) pathological image analysis: the number of regenerated nerve fibers, the diameter and myelin thickness of regenerated nerve fiber were measured. Results: (1) Scar tissue was formed in traditional suture anastomotic adhesions; in simple small gap suture group, obvious adhesions was not found surrounding the tissue; for combination group of small gap suture with nerve debris, there was no obvious adhesions, and the outer membrane of small gap turned thinner than before. (2) Compared with the normal control group, the wet weight was increased significantly in the small gap suture group; relative to the small gap group, the wet weight was increased significantly in the small gap plus nerve fragments group. (3) Compared with the control group, the total number of myelinated nerve fibers was increased significantly in the small-gap suture group and small gap plusnerve fragments group; the diameter of nerve fibers and myelin thickness were increased significantly in simple small gap group and the small gap plus nerve debris group. (4) Histology showed: Compared with simple small gap suture group, nerve fiber density was increased, arrangement is neat in the small gap plus nerve fragments group. Conclusions: The nerve fragments plus epineurium small gap suture has a significant role in the repair of peripheral nerve injury.