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Defects of the peripheral nervous system are extremely frequent in trauma and surgeries and have high socioeconomic costs. If the direct suture of a lesion is not possible, i.e., nerve gap > 2 cm, it is necessary to use grafts. While the gold standard is the autograft, it has disadvantages related to its harvesting, with an inevitable functional deficit and further morbidity. An alternative to autografting is represented by the acellular nerve allograft (ANA), which avoids disadvantages of autograft harvesting and fresh allograft rejection. In this research, the authors intend to transfer to human nerves a novel technique, previously implemented in animal models, to decellularize nerves. The new method is based on soaking the nerve tissues in decellularizing solutions while associating ultrasounds and freeze-thaw cycles. It is performed without interrupting the sterility chain, so that the new graft may not require post-production γ-ray irradiation, which is suspected to affect the structural and functional quality of tissues. The new method is rapid, safe, and inexpensive if compared with available commercial ANAs. Histology and immunohistochemistry have been adopted to evaluate the new decellularized nerves. The study shows that the new method can be applied to human nerve samples, obtaining similar, and, sometimes better, results compared with the chosen control method, the Hudson technique.

Background: Treatment of nerve injuries proves to be a worldwide clinical challenge. Vascularized nerve grafts are suggested to be a promising alternative for bridging a nerve gap to the current gold standard, an autologous non-vascularized nerve graft. However, there is no adequate clinical evidence for the beneficial effect of vascularized nerve grafts and they are still disputed in clinical practice., Objective: To systematically review whether vascularized nerve grafts give a superior nerve recovery compared to non-vascularized nerve autografts regarding histological and electrophysiological outcomes in animal models., Material and Methods: PubMed and Embase were systematically searched. The inclusion criteria were as follows: 1) the study was an original full paper which presented unique data; 2) a clear comparison between a vascularized and a non-vascularized autologous nerve transfer was made; 3) the population study were animals of all genders and ages. A standardized mean difference and 95% confidence intervals for each comparison was calculated to estimate the overall effect. Subgroup analyses were conducted on graft length, species and time frames., Results: Fourteen articles were included in this review and all were included in the meta-analyses. A vascularized nerve graft resulted in a significantly larger diameter, higher nerve conduction velocity and axonal count compared to an autologous non-vascularized nerve graft. However, during sensitivity analysis the effect on axonal count disappeared. No significant difference was observed in muscle weight., Conclusion: Treating a nerve gap with a vascularized graft results in superior nerve recovery compared to non-vascularized nerve autografts in terms of axon count, diameter and nerve conduction velocity. No difference in muscle weight was seen. However, this conclusion needs to be taken with some caution due to the inherent limitations of this meta-analysis. We recommend future studies to be performed under conditions more closely resembling human circumstances and to use long nerve defects., Competing Interests: The authors have declared that no competing interests exist.

The main aim of this study was to evaluate the efficacy of cerium oxide nanoparticles (CNPs) encapsulated in fabricated hybrid silk-fibroin (SF)/polycaprolactone (PCL) nanofibers as an artificial neural guidance conduit (NGC) applicable for peripheral nerve regeneration. The NGC was prepared by PCL and SF filled with CNPs. The mechanical properties, contact angle, and cell biocompatibility experiments showed that the optimized concentration of CNPs inside SF and SF/PCL wall of conduits was 1% (wt/wt). The SEM image analysis showed the nanoscale texture of the scaffold in different topologies depend on composition with fiber diameters at about 351 ± 54 nm and 420 ± 73 nm respectively for CNPs + SF and CNPs + SF/PCL fibrous mats. Furthermore, contact angle measurement confirmed the hydrophilic behavior of the membranes, ascribable to the SF content and surface modification through modified methanol treatment. The balance of morphological and biochemical properties of hybrid CNPs 1% (wt/wt) + SF/PCL construct improves cell adhesion and proliferation in comparison with lower concentrations of CNPs in nanofibrous scaffolds. The release of CNPs 1% (wt/wt) from both CNPs + SF and CNPs+ SF/PCL fibrous mats was highly controlled and very slow during the extended time of incubation until 60 days. Fabricated double-layered NGC using CNPs + SF and CNPs + SF/PCL fibers was consistent for application in nervous tissue engineering and regenerative medicine from a structural and biocompatible perspective., (© 2021 Wiley Periodicals LLC.)

Introduction: The gold standard reconstruction for facial reanimation is the functional muscle transfer. The reinnervation of a muscle is never complete, and clinical results are variable with 20% not achieving a satisfactory outcome. We hypothesise that this may be due to a mismatch between the characteristics of the donor nerve and transferred muscle., Method: 81 YFP-16 and 14 YFP-H mice were studied in three intervention groups over three time periods. Two parameters were investigated: the number and surface area of reinnervated neuromuscular junctions and regenerating axons. An assessment was made of motor unit proportions., Results: All cases of nerve repair and nerve graft, the neuromuscular junctions (NMJ) were completely reinnervated by regenerating axons. The number and calibre of the regenerating axons were significantly different from controls for both intervention groups. The motor units were smaller in both intervention groups., Discussion: Reinnervation occurs after nerve repair or graft; however, the arbour was reinnervated by large numbers of much smaller axons. These axons showed some evidence of remodelling in the repair group, but not in the graft group. Neither group achieved the parameters of the control group. There were persistent qualitative changes to the morphology of both axons and junctions. Imaging documented both synkinesis and alterations that resemble those seen in ageing., Conclusion: Overall, the efficacy of reinnervation is very high with all NMJ reoccupied by regenerating axons. The way small axons are remodelled is different in the nerve repairs compared with the nerve grafts., Competing Interests: Declaration of Competing Interest None declared., (Crown Copyright © 2020. Published by Elsevier Ltd. All rights reserved.)

Microvascular disturbance, excessive inflammation and gliosis are key pathophysiologic changes in relation to functional status following the traumatic spinal cord injury (SCI). Continuous release of vascular endothelial growth factor (VEGF) to the lesion site was proved be able to promote the vascular remodelling, whereas the effects on reduction of inflammation and gliosis remain unclear. Currently, aiming at exploring the synergistic roles of VEGF and neurotrophin-3 (NT-3) on angiogenesis, anti-inflammation and neural repair, we developed a technique to co-deliver VEGF 165 and NT-3 locally with a homotopic graft of tissue-engineered acellular spinal cord scaffold (ASCS) in a hemisected (3 mm in length) SCI model. As the potential in secretion of growth factors (GFs), bone mesenchymal stem cells (BMSCs) were introduced with the aim to enhance the VEGF/NT-3 release. Our data demonstrate that sustained VEGF/NT-3 release from ASCS significantly increases the local levels of VEGF/NT-3 and angiogenesis, regardless of whether it is in combination with BMSCs transplantation that exhibits positive effects on anti-inflammation, axonal outgrowth and locomotor recovery. This study verifies that co-delivery of VEGF/NT-3 reduces inflammation and gliosis in the hemisected spinal cord, promotes axonal outgrowth and results in better locomotor recovery, while the BMSCs transplantation facilitates these functions limitedly.

In this paper, we describe the application of the 4D biofabrication approach for the fabrication of artificial nerve graft. Bilayer scaffolds consisting of uniaxially aligned polycaprolactone-poly(glycerol sebacate) (PCL-PGS) and randomly aligned methacrylated hyaluronic acid (HA-MA) fibers were fabricated using electrospinning and further used for the culture of PC-12 neuron cells. Tubular structures form instantly after immersion of fibrous bilayer in an aqueous buffer and the diameter of obtained tubes can be controlled by changing bilayer parameters such as the thickness of each layer, overall bilayer thickness, and medium counterion concentration. Designed scaffolds showed a self-folded scroll-like structure with high stability after four weeks of real-time degradation. The significance of this research is in the fabrication of tuneable tubular nerve guide conduits that can simplify the current existing clinical treatment of neural injuries.

Purpose: To investigate the effects of Chemically Extracted Acellular Nerves (CEANs) when combined with Adipose-Derived mesenchymal Stem Cell (ADSC) transplantation on the repair of sciatic nerve defects in rabbits., Methods: A total of 71 six-month-old Japanese rabbit were used in this study. Twenty rabbits served as sciatic nerve donors, while the other 51 rabbits were randomly divided into Autologous Nerve Transplantation Group (ANT, n=17), CEAN group (n=17) and CEAN-ADSCs group (n=17). In all these groups, the rabbit's left sciatic nerves were injured before the experiment, and the uninjured sciatic nerves on their right side were used as the control (CON). Electrophysiological tests were carried out and sciatic nerves were prepared for histomorphology and stretch testing at 24 weeks post-transplant., Results: There were significant differences between ANT and Con groups in amplitude (AMP): P=0.031; motor nerve conduction velocity (MNCV): P=0.029; Maximum stress: P=0.029; and Maximum strain P=0.027. There were also differences between the CEAN and CEAN+ADSCs groups in AMP: P=0.026, MNCV: P=0.024; Maximum stress: P=0.025 and Maximum strain: P=0.030. No significant differences in these parameters were observed when comparing the ANT and CEAN+SACN groups (MNCV: P=0.071) or the CEAN and ANT groups (Maximum stress: P=0.069; Maximum strain P=0.077)., Conclusion: Addition of ADSCs has a significant impact on the recovery of nerve function, morphology, and tensile mechanical properties following sciatic nerve injury.

Introduction: Critical limitations of processed acellular nerve allograft (PNA) are linked to Schwann cell function. Side-to-side bridge grafting may enhance PNA neurotrophic potential., Methods: Sprague-Dawley rats underwent tibial nerve transection and immediate repair with 20-mm PNA (n = 33) or isograft (ISO; n = 9) or 40-mm PNA (n = 33) or ISO (n = 9). Processed acellular nerve allograft groups received zero, one, or three side-to-side bridge grafts between the peroneal nerve and graft. Muscle weight, force generation, and nerve histomorphology were tested 20 weeks after repair. Selected animals underwent neuron back labeling with fluorescent dyes., Results: Inner axon diameters, g-ratios, and axon counts were smaller in the distal vs proximal aspect of each graft (P < .05). Schwann cell counts were greater, with a lower proportion of senescent cells for groups with bridges (P < .05). Retrograde labeling demonstrated that 6.6% to 17.7% of reinnervating neurons were from the peroneal pool., Discussion: Bridge grafting positively influenced muscle recovery and Schwann cell counts and senescence after long PNA nerve reconstruction., (© 2019 Wiley Periodicals, Inc.)

Autologous nerve transplantation, which is the gold standard for clinical treatment of peripheral nerve injury, still has many limitations. In this study, aligned chitosan fiber hydrogel (ACG) grafted with a bioactive peptide mixture consisting of RGI (Ac-RGIDKRHWNSQGG) and KLT (Ac-KLTWQELYQLKYKGIGG), designated as ACG-RGI/KLT, was used as nerve conduit filler to repair sciatic nerve defects in rats. Methods : Chitosan nanofiber hydrogel was prepared by a combination of electrospinning and mechanical stretching methods, and was then grafted with RGI and KLT, which are peptides mimicking brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF), respectively. The physicochemical properties of ACG-RGI/KLT were fully characterized. In vitro , the distribution, proliferation, and secretory activity of Schwann cells were analyzed. Next, the in vivo repair potential for 15-mm rat sciatic nerve defects was examined. The recovery of regenerated nerve, muscle, and motor function was evaluated by neuromuscular histology, electrophysiology, and catwalk gait analysis. Results : We first constructed directionally aligned chitosan nanofiber hydrogel grafted with RGI/KLT peptide mixture (ACG-RGI/KLT). ACG-RGI/KLT oriented the Schwann cells, and promoted the proliferation and secretion of neurotrophic factors by Schwann cells. At an early injury stage, ACG-RGI/KLT not only enhanced nerve regeneration, but also promoted vascular penetration. At 12 weeks, ACG-RGI/KLT facilitated nerve regeneration and functional recovery in rats. Conclusions : Aligned chitosan nanofiber hydrogel grafted with RGI/KLT peptide provides an effective means of repairing sciatic nerve defects and shows great potential for clinical application., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Trauma-associated peripheral nerve defect is a widespread clinical problem. Autologous nerve grafting, the current gold standard technique for the treatment of peripheral nerve injury, has many internal disadvantages. Emerging studies showed that tissue engineered nerve graft is an effective substitute to autologous nerves. Tissue engineered nerve graft is generally composed of neural scaffolds and incorporating cells and molecules. A variety of biomaterials have been used to construct neural scaffolds, the main component of tissue engineered nerve graft. Synthetic polymers (e.g. silicone, polyglycolic acid, and poly(lactic-co-glycolic acid)) and natural materials (e.g. chitosan, silk fibroin, and extracellular matrix components) are commonly used along or together to build neural scaffolds. Many other materials, including the extracellular matrix, glass fabrics, ceramics, and metallic materials, have also been used to construct neural scaffolds. These biomaterials are fabricated to create specific structures and surface features. Seeding supporting cells and/or incorporating neurotrophic factors to neural scaffolds further improve restoration effects. Preliminary studies demonstrate that clinical applications of these neural scaffolds achieve satisfactory functional recovery. Therefore, tissue engineered nerve graft provides a good alternative to autologous nerve graft and represents a promising frontier in neural tissue engineering., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: Chronic consumption of most drugs of abuse leads to brain oxidative stress and neuroinflammation, which inhibit the glutamate transporter GLT-1, proposed to perpetuate drug intake. The present study aimed at inhibiting chronic ethanol and nicotine self-administration and relapse by the non-invasive intranasal administration of antioxidant and anti-inflammatory secretome generated by adipose tissue-derived activated mesenchymal stem cells. The anti-addiction mechanism of stem cell secretome is also addressed., Methods: Rats bred for their alcohol preference ingested alcohol chronically or were trained to self-administer nicotine. Secretome of human adipose tissue-derived activated mesenchymal stem cells was administered intranasally to animals, both (i) chronically consuming alcohol or nicotine and (ii) during a protracted deprivation before a drug re-access leading to relapse intake., Results: The intranasal administration of secretome derived from activated mesenchymal stem cells inhibited chronic self-administration of ethanol or nicotine by 85% and 75%, respectively. Secretome administration further inhibited by 85-90% the relapse "binge" intake that occurs after a protracted drug deprivation followed by a 60-min drug re-access. Secretome administration fully abolished the oxidative stress induced by chronic ethanol or nicotine self-administration, shown by the normalization of the hippocampal oxidized/reduced glutathione ratio, and the neuroinflammation determined by astrocyte and microglial immunofluorescence. Knockdown of the glutamate transporter GLT-1 by the intracerebral administration of an antisense oligonucleotide fully abolished the inhibitory effect of the secretome on ethanol and nicotine intake., Conclusions: The non-invasive intranasal administration of secretome generated by human adipose tissue-derived activated mesenchymal stem cells markedly inhibits alcohol and nicotine self-administration, an effect mediated by the glutamate GLT-1 transporter. Translational implications are envisioned.

Objective: Chronic application of brain implants monitoring or modulating neuronal activity are hindered by the foreign body response of the tissue. Topographical modification of implant surfaces may reduce negative tissue response by imitating the structure of the extracellular matrix and therefore affecting the attachment and behavior of neural cells., Approach: In our in vitro study, the effect of nanostructuring was investigated on two commercially used neural implant materials: silicon and platinum. The adhesion, survival and arrangement of neural stem cells (NE4C) and microglial cells (BV2) were investigated and compared to nanostructured and flat Si and Pt surfaces using cell viability studies and fluorescent microscopy image analysis., Main Results: Our data indicated that neural cells established strong adhesive couplings with each other, instead of binding to the artificial surfaces., Significance: The phenomena resemble some features of in vivo separation of living tissue from the implanted artificial material, providing an in vitro model for studying immune response.

Introduction: Various methods have been suggested to improve fat graft survival and decrease graft loss. The exact mechanism of fat graft survival is still unclear, and new strategies are needed to further investigate it., Materials and Methods: The efficacy of epineural sheath in fat volume maintenance was tested in rat model. Five experimental groups were created: group 1, fat graft without any coverage; group 2, epineural sheath tube alone; group 3, epineural sheath tube filled with fat graft; group 4, fat graft mixed with minced epineural sheath without any coverage; and group 5, fat graft covered with the epineural sheath patch. All grafts were implanted into the dorsal subcutaneous region and were followed for up to 12 weeks, when samples were harvested for hematoxylin and eosin and immunostaining for vascular endothelial growth factor expression and perilipin evaluation of fat viability., Results: In groups 1 and 4, over 25% of graft loss was observed at first week, over 50% at third week, and 100% at sixth week postimplantation. The weight of fat graft within the epineural sheath tube and the weight of epineural tube (ET) alone were maintained up to 12 weeks postimplantation. The weight of fat graft within the epineural patch was maintained up to 6 weeks, but 50% of weight loss was observed between 6 and 12 weeks. Structure of the epineural sheath tubes and patches was intact, and no leakage of fat graft was observed. Based on hematoxylin and eosin staining, normal structure and integrity of the fat graft within the ET were preserved up to 12 weeks postimplantation. Characteristic adipocyte morphology was confirmed by perilipin staining, showing viable fat cells in groups 3 and 5 at 12 weeks. Increased vascular endothelial growth factor expression was observed in groups 2, 3, 4, and 5., Conclusions: Both, the ETs and epineural patches maintained 100% and 50% of fat graft weight at 12 weeks postimplantation, respectively. These results were confirmed by histology and immunostaining showing viable adipocytes within the epineural patches (6 weeks) and tubes (12 weeks). These results are encouraging and justify further evaluation of fat volume maintenance in preclinical large animal model in preparation to clinical application.

Purpose of Review: The purpose of this review was to review the imaging, particularly positron emission tomography (PET), findings in neurorestoration studies in movement disorders, with specific focus on neural transplantation in Parkinson's disease (PD) and Huntington's disease (HD)., Recent Findings: PET findings in PD transplantation studies have shown that graft survival as reflected by increases in dopaminergic PET markers does not necessarily correlate with clinical improvement. PD patients with more denervated ventral striatum and more imbalanced serotonin-to-dopamine ratio in the grafted neurons tended to have worse outcome. In HD transplantation studies, variable graft survival and clinical responses may be related to host inflammatory/immune responses to the grafts. Information gleaned from imaging findings in previous neural transplantation studies has been used to refine study protocol and patient selection in future trials. This includes identifying suitable candidates for transplantation using imaging markers, employing multiple and/or novel PET tracers to better assess graft functions and inflammatory responses to grafts.

Background: Tissue processing to create immunotolerant nerve allograft removes neurosupportive cells. Few strategies have been described for implanting new cells into the graft to support axonal regeneration., New Method: Micropuncture of the nerve allograft surface combined with immersion into a pressurized cell-rich solution to potentiate the introduction of viable Schwann cells (SC) into processed nerve allograft. Allografts were used to repair rodent sciatic nerve defects. At 3, 7, and 21days, grafts were harvested, stained for SCs, and analyzed using total cross sectional area (CSA) occupied by SCs to quantify SC presence., Results: At days 3 and 7, SC CSA was significantly greater for the injection group compared to all other groups. At day 21, SC CSA for the injection group (0.2252%±0.2730) was significantly greater compared to following groups: pressurized-punctured (0.0653%±0.0934), nonpressurized-nonpunctured (0.0607%±0.0709), punctured-control (0.0246%±0.0398), and nonpunctured-control (0.0126%±0.0151). A significant decrease in percent CSA occupied by SCs from day 3 to day 21 was noted in nonpressurized-punctured group (p=0.0106), pressurized-nonpunctured group (p=0.0477), and injection group (p=0.0010)., Comparison With Existing Method(s): Most studies have used small caliber hypodermic needles to inject the cells into grafts., Conclusions: Despite a presumed decrease in cell viability over the three weeks of the study, the large initial inoculum achieved by injection technique results in higher levels of final SC seeding in acellular nerve allograft compared with bathing techniques with or without micropuncture or pressurization., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Dissection of the cavernous nerves during radical prostatectomy for prostate cancer eliminates spontaneous erections. Using the rat as an experimental model, we compared the regenerative capacity of autologous nerve grafts and Schwann-cell-seeded nerve guides. After bilateral excision of cavernous nerve segments, cavernous nerves were reconstructed using unseeded silicon tubes, nerve autografts and silicon tubes seeded with either Glial-cell-line-derived (GDNF)-overexpressing or green fluorescent protein (GFP)-expressing Schwann cells (SCs) (16 study nerves per group). Control groups underwent either a sham operation or bilateral excision of cavernous nerve segments without repair. After 12 weeks erectile function was assessed by neurostimulation and intracavernous pressure (ICP) measurement. The reconstructed nerve segments were excised and histologically analyzed. We demonstrated an intact erectile response upon neurostimulation in 25% (4/16) of autologous nerve grafts, in 50% (8/16) of unseeded tubes, in 75% (12/16) of the Schwann-cell-GFP group and in 93.75% (15/16) of the GDNF group. ICP was significantly increased when comparing the Schwann-cell-GFP group with nerve autografts, unseeded conduits and negative controls (P<0.005). In conclusion, Schwann-cell-seeded scaffolds combined with neurotrophic factors are superior to unseeded tubes and autologous nerve grafts. They present a promising therapeutic approach for the repair of erectile nerve gaps., Competing Interests: The authors declare no competing or financial interests., (© 2016. Published by The Company of Biologists Ltd.)

Background: Chronic denervation resulting from long nerve regeneration times and distances contributes greatly to suboptimal outcomes following nerve injuries. Recent studies showed that multiple nerve grafts inserted between an intact donor nerve and a denervated distal recipient nerve stump (termed "side-to-side nerve bridges") enhanced regeneration after delayed nerve repair., Objective: To examine the cellular aspects of axon growth across these bridges to explore the "protective" mechanism of donor axons on chronically denervated Schwann cells., Methods: In Sprague Dawley rats, 3 side-to-side nerve bridges were placed over a 10-mm distance between an intact donor tibial (TIB) nerve and a recipient denervated common peroneal (CP) distal nerve stump. Green fluorescent protein-expressing TIB axons grew across the bridges and were counted in cross section after 4 weeks. Immunofluorescent axons and Schwann cells were imaged over a 4-month period., Results: Denervated Schwann cells dedifferentiated to a proliferative, nonmyelinating phenotype within the bridges and the recipient denervated CP nerve stump. As donor TIB axons grew across the 3 side-to-side nerve bridges and into the denervated CP nerve, the Schwann cells redifferentiated to the myelinating phenotype. Bridge placement led to an increased mass of hind limb anterior compartment muscles after 4 months of denervation compared with muscles whose CP nerve was not "protected" by bridges., Conclusion: This study describes patterns of donor axon regeneration and myelination in the denervated recipient nerve stump and supports a mechanism where these donor axons sustain a proregenerative state to prevent deterioration in the face of chronic denervation.

Objective: To summarize the research progress of autologous vein nerve conduit for the repair of peripheral nerve defect., Methods: The recent domestic and foreign literature concerning autologous vein nerve conduit for repair of peripheral nerve defect was analyzed and summarized., Results: A large number of basic researches and clinical applications show that the effect of autologous venous nerve conduit is close to that of autologous nerve transplantation in repairing short nerve defect, especially the compound nerve conduit has a variety of autologous nerve tissue, cells, and growth factors, etc., Conclusion: Autologous vein nerve conduit for repair of non-nerve defect can be a good supplement of autologous nerve graft, improvement of autologous venous catheter to repair peripheral nerve defect is the research direction in the future.

Background: The authors evaluated the efficacy of decellularized nerve as a scaffold for nerve regeneration., Methods: Sciatic nerves harvested from Sprague-Dawley rats were decellularized in combination with sodium dodecyl sulfate and Triton X-100, and examined with scanning electron microscopy and immunofluorescence staining. A graft into the sciatic nerve in Wistar rats was performed with the decellularized Sprague-Dawley rat sciatic nerves [allograft: 10 mm long (n = 3) for short term and 15 mm long (n = 5) for long term]. As a control, a portion of sciatic nerve of Wistar rats was cut, reversed, and resutured in situ [autograft: 10 mm long (n = 3) and 15 mm long (n = 5) for different terms, respectively]. Samples were harvested 4 weeks postoperatively and prepared for immunohistochemistry. Von Frey hair test, static toe spread factor measurement, and electrophysiologic and histomorphologic analyses were carried out to evaluate nerve recovery 24 weeks postoperatively., Results: Scanning electron microscopic images revealed the honeycomb structure, and immunohistology showed that the three-dimensional structure of the basal lamina column on which cell adhesion molecules are integrated is preserved through the decellularization protocols. Limited ED1-positive macrophage invasion was found through the decellularized sciatic nerves, suggesting that antigenicity remained more or less after this treatment. Nevertheless, NF160-positive axons accompanied by S100-positive Schwann cells penetrated through the decellularized sciatic nerves. Sciatic nerve function had recovered, and there were no significant differences in the electrophysiologic and histomorphologic recovery in the groups., Conclusion: These results suggest that the decellularized allogeneic nerve is a suitable scaffold to bridge a nerve gap.

Inhibition of β-site APP cleaving enzyme 1 (BACE1) is being pursued as a therapeutic target for treating patients with Alzheimer's disease because BACE1 is the sole β-secretase for generating β-amyloid peptide. Knowledge regarding the other cellular functions of BACE1 is therefore critical for the safe use of BACE1 inhibitors in human patients. BACE1 deficiency in mice causes hypomyelination during development and impairs remyelination in injured sciatic nerves. Since BACE1 is expected to be ubiquitously expressed, we asked whether axonal or Schwann cell BACE1 is required for optimal remyelination. By swapping sciatic nerve segments from BACE1-null mice with the corresponding wild-type nerve segments or vice versa, we tested how a deficiency of BACE1 in Schwann cells or axons affects remyelination. Our results show that BACE1 in axons and Schwann cells is similarly important for remyelination of regenerated axons. Nerve injury induces BACE1 transcription and protein levels are elevated in Schwann cells. Expression of type I neuregulin 1 (Nrg1), rather than type III Nrg1, was induced by Schwann cells, and the abolished Nrg1 cleavage in BACE1-null Schwann cells contributed to decreased remyelination of regenerated axons. Hence, this study is the first to demonstrate the equal importance of axonal and Schwann cell BACE1 for remyelination of injured nerves., (Copyright © 2015 the authors 0270-6474/15/353806-09$15.00/0.)

Object: The objective of this study was to report the results of elbow, thumb, and finger extension reconstruction via nerve transfer in midcervical spinal cord injuries., Methods: Thirteen upper limbs from 7 patients with tetraplegia, with an average age of 26 years, were operated on an average of 7 months after a spinal cord injury. The posterior division of the axillary nerve was used to reinnervate the triceps long and upper medial head motor branches in 9 upper limbs. Both the posterior division and the branch to the middle deltoid were used in 2 upper limbs, and the anterior division of the axillary nerve in the final 2 limbs. For thumb and finger extension reconstruction, the nerve to the supinator was transferred to the posterior interosseous nerve., Results: In 22 of the 27 recipient nerves, a peripheral type of palsy with muscle denervation was identified. At an average of 19 months follow-up, elbow strength scored M4 in 11 upper limbs and M3 in 2, according to the British Medical Research Council scale. Thumb extension scored M4 in 8 upper limbs and scored M3 in 4. Finger extension scored M4 in 12 hands. No donor-site deficits were reported or observed., Conclusions: Nerve transfers are effective at restoring elbow, thumb, and finger extension in patients with a midcervical spinal cord injury, which occurs in the majority of patients with a peripheral type of palsy with muscle denervation in their upper limbs. Efforts should be made to perform operations in these patients within 12 months of injury.

Adipose-derived stem cells were isolated from rats and differentiated to a Schwann cell-like phenotype in vitro. The differentiated cells (dADSCs) underwent self-alignment in a tethered type-1 collagen gel, followed by stabilisation to generate engineered neural tissue (EngNT-dADSC). The pro-regenerative phenotype of dADSCs was enhanced by this process, and the columns of aligned dADSCs in the aligned collagen matrix supported and guided neurite extension in vitro. EngNT-dADSC sheets were rolled to form peripheral nerve repair constructs that were implanted within NeuraWrap conduits to bridge a 15 mm gap in rat sciatic nerve. After 8 weeks regeneration was assessed using immunofluorescence imaging and transmission electron microscopy and compared to empty conduit and nerve graft controls. The proportion of axons detected in the distal stump was 3.5 fold greater in constructs containing EngNT-dADSC than empty tube controls. Our novel combination of technologies that can organise autologous therapeutic cells within an artificial tissue construct provides a promising new cellular biomaterial for peripheral nerve repair., (Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Introduction: Peripheral nerve injuries are encountered frequently in clinical practice. In nerve repair, an end-to-end suture is the preferable choice of treatment. However, where primary closure is not possible, the defect is to be repaired with a nerve graft., Methods: A total of 21 female Wistar rats weighing 230 to 290 g were used in the study. They were classified into the following 3 groups: (I) nerve graft, (II) vein graft, and (III) minced nerve graft. In group I, after exposure of the tibial nerve, a 1-cm-long nerve gap was created on the tibial nerve, and the defect was repaired epineurally by using the autogenous nerve. In group II, the 1-cm tibial nerve defect was repaired by using an autogenous vein graft. In group III, a 1-cm nerve graft was divided to 3 equal parts, with one of the nerve parts being minced with microscissors and placed in the vein graft lumen. Thereafter, a 1-cm tibial nerve defect was repaired by the vein graft filled with minced nerve tissue. The tibial function indices (TFIs) were calculated for functional assessment using the Bain-Mackinnon-Hunter formula. Light and electron microscopic evaluations were performed for morphometric assessment. In addition, the myelinated fibers were counted in all groups., Results: The TFIs of group II were found to be the lowest among all the groups after the sixth week, whereas the TFI of group I was found to be better than the other groups after the sixth week. There was no difference in TFIs between group I and group III. On the basis of the number of myelinated fibers, there was no statistically significant difference between group I and group III, whereas the difference was significant (P<0.05) between groups I/III and group II. Presence of peripheral nerves in light microscopic evaluation revealed normal characteristics of myelinated fibers in all groups. The myelinated axon profile was near normal in the nerve graft group in electron microscopic evaluation. However, there were more degenerated axons with disturbed contours and vacuolizations in the vein graft group compared to the minced nerve graft group., Conclusions: We can conclude that using minced nerve tissue in vein grafts as a conduit increases the regeneration of nerves (almost like the nerve graft group) and it may not be caused by donor-site morbidity. It can be used in the repair of nerve defects instead of autogenous nerve grafts after further experimental evidence and clinical trials.

This study evaluated whether bone marrow-derived mesenchymal stem cells (BM-MSCs) combined with xenogeneic acellular nerve grafts (xANGs) would reduce the inflammation reaction of xANGs transplantation. BM-MSCs were extracted, separated, purified, and cultured from the bone marrow of rats. Then BM-MSCs were seeded into 5 mm xANGs as experimental group, while xANGs group was chosen as control. Subcutaneous implantation and nerve grafts transplantation were done in this study. Walking-track tests, electrophysiological tests, H&E staining, and immunostaining of CD4, CD8, and CD68 of subcutaneous implantations, cytokine concentrations of IL-2, IL-10, IFN-γ and TNF-α in lymphocytes supernatants and serum of the two groups were evaluated. Walking-track tests and electrophysiological tests suggested the group of BM-MSCs with xANGs obtained better results than xANGs group (P < 0.05). H&E staining and immunostaining of CD4, CD8, and CD68 of subcutaneous implantations showed there were less inflammatory cells in the group of BM-MSCs when compared with the xANGs group. The cytokine concentrations of IL-2, IFN-γ, and TNF-α in BM-MSCs group were lower than xANGs group in lymphocytes supernatants and serum (P < 0.05). However, IL-10 concentrations in BM-MSCs group were higher than xANGs group (P < 0.05). xANG with BM-MSCs showed better nerve repair function when compared with xANG group. Furthermore, xANG with BM-MSCs showed less inflammatory reaction which might indicate the reason of its better nerve regeneration.

The present work compared the local injection of mononuclear cells to the spinal cord lateral funiculus with the alternative approach of local delivery with fibrin sealant after ventral root avulsion (VRA) and reimplantation. For that, female adult Lewis rats were divided into the following groups: avulsion only, reimplantation with fibrin sealant; root repair with fibrin sealant associated with mononuclear cells; and repair with fibrin sealant and injected mononuclear cells. Cell therapy resulted in greater survival of spinal motoneurons up to four weeks post-surgery, especially when mononuclear cells were added to the fibrin glue. Injection of mononuclear cells to the lateral funiculus yield similar results to the reimplantation alone. Additionally, mononuclear cells added to the fibrin glue increased neurotrophic factor gene transcript levels in the spinal cord ventral horn. Regarding the motor recovery, evaluated by the functional peroneal index, as well as the paw print pressure, cell treated rats performed equally well as compared to reimplanted only animals, and significantly better than the avulsion only subjects. The results herein demonstrate that mononuclear cells therapy is neuroprotective by increasing levels of brain derived neurotrophic factor (BDNF) and glial derived neurotrophic factor (GDNF). Moreover, the use of fibrin sealant mononuclear cells delivery approach gave the best and more long lasting results.

Background: This study evaluated whether Schwann-like cells (SLCs) induced from bone marrow-derived mesenchymal stem cells (BM-MSCs) transplanted into acellular nerve grafts (ANGs) could repair nerve defects compared with nerve isografts and ANGs with BM-MSCs., Methods: BM-MSCs extracted, separated and purified from the bone marrow of rats, and some of the BM-MSCs were cultured with mixed induction agents that could induce BM-MSCs into SLCs. Either SLCs or BM-MSCs were seeded onto 10-mm ANGs, and the isografts were chosen as the control. The walking-track test, tibialis anterior muscle weight measurement, electrophysiological examination, toluidine blue staining, transmission electron micrographs and immunostaining of S-100 and VEGF in these three groups were evaluated in a 10-mm rat sciatic injury-repair model., Results: The walking-track test, tibialis anterior muscle weight measurement and electrophysiological examination of the sciatic nerve suggested the groups of ANGs with SLCs and isografts obtained better results than the BM-MSC group (P<0.05). Meanwhile, the results of the SLCs and isograft groups were similar (P>0.05). All the histomorphometric analyses (toluidine blue staining, transmission electron micrographs and immunostaining of S-100 and VEGF) showed that there were more regenerating nerve fibers in the group of ANGs with SLCs than the BM-MSCs (P<0.05), but there was no significant difference between the SLC and isograft groups (P>0.05)., Conclusions: SLCs seeded in ANGs and isografts show better functional regeneration compared with BM-MSCs seeded in ANGs. Additionally, SLCs combined with ANGs present almost the same outcome as the isografts. Therefore, SLCs with ANGs can be a good choice in nerve defect repairs.

Processed nerve allografts are increasingly used as "off the shelf" nerve replacements for surgically bridging nerve gaps. Benchmarking the regenerative capacity of a commercially available human-derived nerve or xenograft in a rat nerve injury model would provide a convenient platform for future studies seeking to modify the processed nerve graft. Human and rat processed nerve grafts were used to bridge a 14 mm defect in a Sprague-Dawley rat sciatic nerve. Reversed autografts served as a positive control group. Twelve weeks following surgery, the distal nerve stumps were retrograde labeled and harvested for histology and histomorphometry. The cross-sectional areas of the human- and rat-derived processed nerve grafts were similar. Neuron counts and myelinated axon counts following use of the human-derived processed xenografts were decreased compared with those obtained from both the rat-derived processed nerve allografts and the autografts; the rat-derived processed nerve allografts were statistically equivalent to autografts. Measures of nerve fiber diameter and myelination revealed inferior axon regeneration maturity in both processed nerve grafts compared with autografts. Processed xenografts showed significantly reduced regeneration compared with autografts or processed allografts indicating that cross-species immunological reactions are important considerations in this rat model., (Copyright © 2013 Wiley Periodicals, Inc.)

Acellular nerve grafting is often inferior as well as an inadequate alternative to autografting for the repair of long gaps in peripheral nerves. Moreover, the injection method is not perfect. During the injection of cells, the syringe can destroy the acellular nerve structure and the limited accumulation of seed cells. To resolve this problem, we constructed a nerve graft by acellular nerve grafting. Bone marrow-mesenchymal stromal cells (BM-MSCs) were affixed with fibrin glue and injected inside or around the graft, which was then used to repair a 15-mm nerve defect in rats. The acellular nerve graft maintained its structure and composition, and its tensile strength was decreased, as determined by two-photon microscopy and a tensile testing device. In vitro, MSCs embedded in fibrin glue survived and secreted growth factors such as nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). We repaired 15-mm Sprague-Dawley rat sciatic nerve defects using this nerve graft construction, and MSCs injected around the graft helped improve nerve regeneration and functional recovery of peripheral nerve lesions as determined by functional analysis and histology. Therefore, we conclude that supplying MSCs in fibrin glue around acellular nerves is successful in maintaining the nerve structure and can support nerve regeneration similar to the direct injection of MSCs into the acellular nerve for long nerve defects but may avoid destroying the nerve graft. The technique is simple and is another option for stem cell transplantation.

Objective: To investigate the effect of tissue engineering nerve on repair of rat sciatic nerve defect., Methods: Forty-five rats with defective sciatic nerve were randomly divided into three groups. Rats in group A were repaired by acellular nerve grafts only. Rats in group B were repaired by tissue engineering nerve. In group C, rats were repaired by autogenous nerve grafts. After six and twelve weeks, sciatic nerve functional index (SFI), neural electrophysiology (NEP), histological and transmission electron microscope observation, recovery ratio of wet weight of gastrocnemius muscle, regenerated myelinated nerve fibers number, nerve fiber diameter, and thickness of the myelin sheath were measured to assess the effect., Results: After six and twelve weeks, the recovery ratio of SFI and wet weight of gastrocnemius muscle, NEP, and the result of regenerated myelinated nerve fibers in groups B and C were superior to that of group A (P < 0.05), and the difference between groups B and C was not statistically significant (P > 0.05)., Conclusion: The tissue engineering nerve composed of acellular allogenic nerve scaffold and Schwann cells-like cells can effectively repair the nerve defect in rats and its effect was similar to that of the autogenous nerve grafts.

This study reported preliminary clinical experience of using decelluarised nerve allograft material for repair of digital nerve defect in five hand injury patients. From October 2009 to July 2010, five patients with traumatic nerve defect were treated with nerve repair using AxoGen® nerve allograft (AxoGen Inc, Alachua, FL) in California Hospital Medical Center. All patients were followed at least for 12 months, and sensory recovery and signs of infection or rejection were documented by a hand therapist. Average two-point discrimination was 6 mm, and average Semmes-Weinstein Monofilaments test was 4.31. No wound infections or signs of rejections were observed at wound site. All patients reported sensory improvement during the follow-up period after operation. It is believed that decellularised nerve allografts may provide a readily available option for repair of segmental nerve defect.

Severe peripheral nerve defect by injuries causing functional loss require nerve grafting. Autograft has limitations for clinical use because it results in the creation of a new nerve injury and the generation of donor site morbidity. Based on these limitations, nerve allografts and xenografts provide a readily accessible alternative strategy. The aim of the present study was to observe the immune mechanism underlying the rejection of chemically extracted acellular nerve xenografts, and further evaluate immunogenicity of chemically treated acellular nerve grafts for clinical applications. A total of 160 BALB/c mice were randomly divided into a negative contrast group (NC, 40 mice), a fresh autograft group (AG, 40 mice), a fresh xenogeneic nerve group (FXN, 40 mice) and a chemically extracted acellular xenogeneic nerve group (CEXN, 40 mice). Various types of nerve grafts were implanted into the thigh muscle of BALB/C mice in the corresponding groups. At 3, 7, 14 and 28 days post-operation, the mice (10 mice from each group) were sacrificed and their spleens were extracted. The spleens were ground into paste. The erythrocytes and other cells were lysed using distilled water and the T lymphocytes were collected. Fluorescein isothiocyanate (FITC) -labeled monoclonal antibodies (CD3, CD4, CD8, CD25, IL-2, IFN-γ and TNF-α) were then added to the solution. The Fluorescence Activated Cell Sorting (FACS) was used to determine the positivity rate of the cells combined with the monoclonal antibodies above. No significant statistical differences were observed between the CEXN, NC and AG groups, so that no obvious immune rejections were observed among the chemically extracted acellular nerve xenografts.

Background: Recovery from peripheral nerve repair is frequently incomplete. Hence drugs that enhance nerve regeneration are needed clinically., Objectives: To study the effects of nandrolone decanoate in a model of deficient reinnervation in the rat., Methods: In 40 rats, a 40-mm segment of the left median nerve was removed and interposed between the stumps of a sectioned right median nerve. Starting 7 days after nerve grafting and continuing over a 6-month period, we administered nandrolone at a dose of 5 mg/kg/wk to half the rats (n = 20). All rats were assessed behaviorally for grasp function and nociceptive recovery for up to 6 months. At final assessment, reinnervated muscles were tested electrophysiologically and weighed. Results were compared between rats that had received versus not received nandrolone and versus 20 nongrafted controls., Results: Rats in the nandrolone group recovered finger flexion faster. At 90 days postsurgery, they had recovered 42% of normal grasp strength versus just 11% in rats grafted but not treated with nandrolone. At 180 days, the average values for grasp strength recovery in the nandrolone and no-nandrolone groups were 40% and 33% of normal values for controls, respectively. At 180 days, finger flexor muscle twitch strength was 16% higher in treated versus nontreated rats. Thresholds for nociception were not detected in either group 90 days after nerve grafting. At 180 days, nociceptive thresholds were significantly lower in the nandrolone group., Conclusions: Nandrolone decanoate improved functional recovery in a model of deficient reinnervation.

Introduction: We sought to determine whether supplementation of acellular nerve allografts (ANAs) with Schwann cells overexpressing GDNF (G-SCs) would enhance functional recovery after peripheral nerve injury., Methods: SCs expanded in vitro were infected with a lentiviral vector to induce GDNF overexpression. Wild-type SCs (WT-SCs) and G-SCs were seeded into ANAs used to repair a 14-mm nerve gap defect. Animals were harvested after 6 and 12 weeks for histomorphometric and muscle force analysis., Results: At 6 weeks, histomorphometry revealed that ANAs supplemented with G-SCs promoted similar regeneration compared with isograft at midgraft. However, G-SCs failed to promote regeneration into the distal stump. At 12 weeks, ANAs with G-SCs had lower maximum and specific force production compared with controls., Conclusions: The combined results suggest that consistent overexpression of GDNF by G-SCs trapped axons in the graft and prevented functional regeneration., (Copyright © 2012 Wiley Periodicals, Inc.)

The influence of breaching the connective sheaths of the donor sural nerve on axonal sprouting into the end-to-side coapted peroneal nerve was examined in the rat. In parallel, the effect of these procedures on the donor nerve was assessed. The sheaths of the donor nerve at the coaptation site were either left completely intact (group A) or they were breached by epineurial sutures (group B), an epineurial window (group C), or a perineurial window (group D). In group A, the compound action potential (CAP) of sensory axons was detected in ~10% and 40% of the recipient nerves at 4 and 8 weeks, respectively, which was significantly less frequently than in group D at both recovery periods. In addition, the number of myelinated axons in the recipient nerve was significantly larger in group D than in other groups at 4 weeks. At 8 weeks, the number of axons in group A was only ~15% of the axon numbers in other groups (p<0.05). Focal subepineurial degenerative changes in the donor nerves were only seen after 4 weeks, but not later. The average CAP area and the total number of myelinated axons in the donor nerves were not different among the experimental groups. In conclusion, myelinated sensory axons are able to penetrate the epiperineurium of donor nerves after end-to-side nerve coaption; however, their ingrowth into recipient nerves is significantly enhanced by breaching the epiperineurial sheets at the coaptation site. Breaching does not cause permanent injury to the donor nerve.

Object: The diaphragmatic height index (DHI) was developed to measure the difference in diaphragm levels. The purpose of this study was to set definite DHI values and test the accuracy of these values for use as a new diagnostic test for phrenic nerve dysfunction., Methods: All data for this study were obtained from medical charts and retrospectively reviewed., Results: One hundred sixty-five patients with brachial plexus injury who had undergone nerve transfers between 2005 and 2008 were divided into Groups A and B. Group A consisted of 40 patients (mean age 28.0 years) who had sustained concomitant injury of the brachial plexus and phrenic nerves. Patients in Group A1 had right phrenic nerve injury and those in Group A2 had left phrenic nerve injury. Intraoperative direct electrical stimulation of the phrenic nerve was considered the gold standard in assessing nerve function in all patients with brachial plexus injury. Group B consisted of 125 patients (mean age 28.7 years) with brachial plexus injury and normal phrenic nerve function. Group C, the control group, consisted of 80 patients with nonbrachial plexus injury (mean age 34.0 years) who had undergone other kinds of orthopedic operations between April and June 2009. Standard posteroanterior chest radiographs were blindly interpreted using the Siriraj inhouse picture archiving and communication system in all 245 patients in the study. First, a reference line (R line) was drawn along the inferior endplate of T-10. Then, 2 lines (lines A and B) were drawn through the highest point of each diaphragm and parallel to the R line. The difference between these 2 lines divided by the height of T-10 was defined as the DHI. The cutoff points of the DHI for diagnosing right and left phrenic nerve dysfunction were analyzed with a receiver operating characteristic curve. The accuracy of these DHI values was then evaluated. The DHI in Group C was 0.64 ± 0.44, slightly higher than the DHI in Group B, with no significant difference. Diaphragmatic height indexes in Groups A1 and A2 were 2.0 ± 0.99 and -1.04 ± 0.83, respectively, which were significantly different from those in Groups B and C (p < 0.05). The cutoff point of the DHI for diagnosing right phrenic nerve dysfunction was > 1.1, and that for left phrenic nerve dysfunction was < 0.2. The sensitivity and specificity of right and left DHI values were 90.5% and 86.3%, and 94.7 and 88.3%, respectively., Conclusions: Data in this study show that diaphragm paralysis can be simply and reliably predicted by the DHI. Diaphragmatic height index values > 1.1 and < 0.2 are proposed as the new diagnostic test for right and left phrenic nerve dysfunction with a high degree of accuracy. This index is applicable in diagnosing phrenic nerve dysfunction that occurs concomitantly with brachial plexus injury or from other etiologies.

Spinal cord injury (SCI) remains a significant public health problem. Despite advances in understanding of the pathophysiological processes of acute and chronic SCI, corresponding advances in translational applications have lagged behind. Nerve transfers using an expendable nearby motor nerve to reinnervate a denervated nerve have resulted in more rapid and improved functional recovery than traditional nerve graft reconstructions following a peripheral nerve injury. The authors present a single case of restoration of some hand function following a complete cervical SCI utilizing nerve transfers.

Objective: To observe the revascularization process of transplanted nerve after transplantation of long nerve and accompanying peripheral vessels, to investigate its relationship with nerve regeneration., Methods: The median nerve defect models of the left forelimb (3 cm in length) were made in 60 New Zealand rabbits (aged 6-8 months, weighing 2.0-2.5 kg, and male or female), which were randomly divided into 2 groups (n=30). In situ anastomosis of the median nerves was performed in the control group; in situ anastomosis of the median nerves was made in parallel to the surrounding elbow veins, the transplanted epineurium and the adventitia were sutured with nerve anastomosis line in the experimental group. After operation, the gross observation, electrophysiological testing, and histopathology observation was performed at 1, 2, 4, 8, and 12 weeks, and transmission electron microscope at 12 weeks to observe the revascularization of nerve grafts, nerve fiber regeneration, and functional recovery., Results: In the experimental group, revascularization was observed at 1 week after operation, and the degree of revascularization was significantly higher than that in the control group at 2, 4, 8, and 12 weeks. At 8 and 12 weeks, the nerve fiber regeneration speed, quality, and quantity in the experimental group were better than those in the control group. At 2, 4, 8, and 12 weeks, the nerve conduction velocities were (10.32 +/- 0.94), (13.14 +/- 1.22), (22.68 +/- 1.16), and (24.09 +/- 1.27) m/s respectively in the experimental group, and were (9.18 +/- 1.07), (11.12 +/- 1.03), (19.81 +/- 1.37), and (20.67 +/- 1.19) m/s in the control group, showing significant difference at 12 weeks after operation (t = 3.167, P = 0.001). At 12 weeks in the experimental group, the myelin sheath had similar size, less sheath plate delamination, normal Schwann cells and rich organelles, in which normal microfilaments, microtubules and axonal mitochondria were observed; axonal mitochondria had clear crest film and no swelling and vacuolization, and the neurofibrils basically became normal. The myelinated nerve fibers area, myelin thickness, and axon diameter were (5.93 +/- 0.94) mm2, (0.72 +/- 0.12) microm, and (3.12 +/- 0.12) microm respectively in the experimental group, and were (5.28 +/- 0.72) mm2, (0.65 +/- 0.09) microm, and (2.98 +/- 0.16) microm respectively in the control group, all showing significant differences (t = 3.736, P = 0.002; t = 3.271, P = 0.002; t = 4.533, P = 0.001)., Conclusion: The transplanted nerves in parallel to large blood vessels can promote angiogenesis of the transplanted nerve, and accelerate the regeneration and functional recovery of the nerves.

Tissue engineered nerve grafts are considered as a promising alternative to autologous nerve grafts used for peripheral nerve repair. The differences between these two types of nerve grafts are mainly in the regenerative microenvironment established by them. To construct ideal tissue engineered nerve grafts, it is therefore required to develop a better way to introduce biochemical cues into a neural scaffold, as compared to single or combined use of support cells and growth factors. Here, we used a co-culture system of dorsal root ganglia and Schwann cells to create an in vitro formed nerve equivalent, which was introduced into a silk fibroin-based scaffold to furnish a tissue engineered nerve graft (TENG). At 4- and 12- weeks after the TENG was implanted to bridge a 10-mm-long sciatic nerve defect in rats, histological and functional assessments as well as Western blot analysis were performed to evaluate the influences of the TENG on peripheral nerve regeneration. We found that at an early stage of nerve regeneration, the TENG significantly accelerated axonal growth, and up-regulated expressions of N-cadherin and PMP22. Twelve weeks after nerve grafting, the TENG produced a further improved outcome of nerve regeneration and functional recovery, which was more close to that of the autologous nerve graft than that of the silk fibroin-based scaffold. The introduction of an in vitro cultured nerve equivalent into a scaffold might contribute to establishing a native-like microenvironment for nerve regeneration., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

This study aimed to evaluate whether combination therapy of bone marrow stromal cells (BMSCs) transplantation and chondroitinase ABC (ChABC) treatment further enhances axonal regeneration and functional recovery after acellular nerve allograft repair of the sciatic nerve gap in rats. Eight Sprague-Dawley rats were used as nerve donors, and 32 Wistar rats were randomly divided into four groups: Group I: acellular rat sciatic nerve (ARSN) group; Group II: ChABC treatment; Group III: BMSCs transplantation; and Group IV: ChABC treatment and BMSCs transplantation. The results showed that compared with ARSN control group, BMSC transplantation promoted axonal regeneration, the secretion of neural trophic factors NGF, BDNF and axon angiogenesis in nerve graft. ChABC treatment degraded chondroitin sulfate proteoglycans in ARSN in vitro and in vivo and improved BMSCs survival in ARSN. The combination therapy caused much better beneficial effects evidenced by increasing sciatic function index, nerve conduction velocity, restoration rate of tibialis anterior wet muscle weight, and myelinated nerve number, but did not further boost the therapeutic effects on neurotrophic factor production, axon angiogenesis, and sensory functional recovery by BMSC transplantation. Taken together, for the first time, we demonstrate the synergistic effects of BMSC transplantation and BMSCs treatment on peripheral nerve regeneration, and our findings may help establish novel strategies for cell transplantation therapy for peripheral nerve injury.

In Parkinson's disease (PD) many motor and non-motor symptoms are difficult to explain in terms of a purely ascending degeneration process as described by Braak. This essay proposes phylogenetic considerations for consolidating the multidimensional elements of PD. Subtle clinical analysis paired with ethological comparisons as well as patho-anatomical data suggests that disrupted automatic gait control, olfactory deficits, selected visual deficits, impaired emotional face recognition, and REM sleep behavior disorder could be due to dysfunction of phylogenetically ancient networks. Neuroanatomical and behavioral findings lead to a reconsideration of the basal ganglia, to be viewed as the nuclear core of a widely distributed neural network that arborizes throughout the primordial core of the neuraxis, including the brainstem. Fragility of the resulting multiple, closed, ancillary loops that link brainstem and forebrain components of the basal ganglia may be a nodal point, pivotal to the pathogenesis of PD. Other primitive neural networks, such as those located at cardiac or gastro-intestinal levels, may share the same vulnerability. Such a network-based hypothesis overrides the need of a fixed temporal ordering of symptoms based on putative caudal-cephalic propagation patterns of pathological lesions. It also creates testable, secondary hypotheses such as differential gene expression in different neural networks, potential early epigenetic influences, concepts of "overuse" or maladaptation of primitive networks to the constraints of adult life, and system frailty due to irreparable mitochondrial "exhaustion" in highly energy consuming postmitotic cells., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Objective: Discuss the molecular mechanism for improving neural regeneration after repair of sciatic nerve defect in rat by acellular nerve allograft (ANA)., Methods: Randomly divide 36 Wistar rats into six groups as normal control group, autografting group, and bridging groups of 2, 4, 8, 12 weeks, six rats for each group. Observe the expression of brain-derived neurotrophic factor (BDNF) in L(4) spinal cord and anterior tibial muscle at the injury site, calcitonin gene-related peptide (CGRP) protein as well as mRNA, respectively. 12w after operation, histopathological observation was performed., Results: 2w after ANA bridging the sciatic nerve defect in rats, it was observed that the expression level of BDNF in spinal cord at the injury site and CGRP protein increased, reaching the peak level at 4w, lasting till 8w, then decreased but still significantly higher than that in normal control group at 12w, and was not significantly different compared with that in autografting group. However, the expression level of BDNF in anterior tibial muscle decreased gradually within the initial 4w, then increased progressively, reaching normal level at 12w, and was not significantly different compared with that in autografting group. The expression of BDNF mRNA and CGRPmRNA was essentially the same. 12w after operation, there was nerve regeneration in bridging group of 12w and autografting group., Conclusions: ANA possessed fine histocompatibility, and might substitute autograft to repair long-segment defect of sciatic nerve in rats. This action might be related to upregulation of protein and mRNA expression for BDNF and CGRP in spinal cord., (Copyright © 2011 Wiley Periodicals, Inc.)

Objective: To investigate the therapeutic effects of co-transplantation with Schwann cells (SCs) and human embryonic nerve stem cells (NSCs) on macaque Parkinson's disease (PD)., Methods: Macaque autologous SCs and human embryonic NSCs were adopted for the treatment of macaque PD., Results: Six months after transplantation, positron emission computerized tomography showed that (18)F-FP-β-CIT was significantly concentrated in the injured striatum in the co-transplanted group. Immunohistochemical staining of transplanted area tissue showed migration of tyroxine hydroxylase positive cells from the transplant area to the surrounding area was significantly increased in the co-transplanted group., Conclusions: Co-transplantation of SCs and NSCs could effectively cure PD in macaques. SCs harvested from the autologous peripheral nerves can avoid rejection and the ethics problems, so it is expected to be applied clinically., (Copyright © 2012 Hainan Medical College. Published by Elsevier B.V. All rights reserved.)

The purpose of this study was to evaluate the effect of direct administration of nerve growth factor (NGF) into an epineural conduit across a short nerve gap (10 mm) in a rabbit sciatic nerve model. The animals were divided into two groups. In group 1, n = 6, a 10-mm defect was created in the sciatic nerve and bridged with an epineural flap. A dose of 1 μg of NGF was locally administered daily for the first 21 days. NGF administration was made inside the epineural flap using a silicone reservoir connected to a silicone tube. In group 2, n = 6, the 10-mm defect was bridged with a nerve graft. This group did not receive any further treatment. At 13 weeks, all animals, before euthanasia, underwent electromyography (EMG) studies and then specimen sent for histology morphometric analysis. NGF administration ensured a significantly increased average number of myelinated axons per μm(2) (P = 0.028) and promoted fiber maturation (P = 0.031) and better EMG results (P = 0.046 for latency P = 0.048 for amplitude), compared with the control group. Although nerve grafts remain the gold standard for peripheral nerve repair, NGF-treated epineural conduits represent a good alternative, particularly when an unfavorable environment for nerve grafts is present., (Copyright © 2011 Wiley-Liss, Inc.)

The injury of the penile cavernous nerve is a common cause of erectile dysfunction (ED). Reconstruction of the resected cavernous nerve can restore penile erectile function to normal. The methods for cavernous nerve repair include direct anastomosis, autotransplantation of the nerve, and substitution of the biodegradable artificial nerve, among which only autotransplantation of the sural nerve is used clinically at present. Besides, the nerve growth factor plays an important role in nerve reconstruction. This paper summarizes the methods of cavernous nerve reconstruction in the recent years.