Artificial Nerve Conduits Research Articles

Efficacy and safety of novel collagen conduits filled with collagen filaments to treat patients with peripheral nerve injury: A multicenter, controlled, open-label clinical trial

IntroductionThe safety and efficacy of using artificial collagen nerve conduits filled with collagen filaments to treat nerve defects has not been fully studied in humans. We conducted a multicenter, controlled, open-label study to compare the safety and efficacy of artificial nerve conduit grafts with those of autologous nerve grafts. MethodsWe included patients with a sensory nerve defect of ≤30 mm, at the level of the wrist or a more distal location, with the first-line surgical methods selected according to a patient’s preference. We compared sensory recovery using static two-point discrimination and adverse events between the artificial collagen nerve conduit and autologous nerve grafting. ResultsThe artificial nerve conduit group included 49 patients, with a mean age of 42 years and nerve defect of 12.6 mm. The autologous nerve graft group included 7 patients, with historical data of an additional 31 patients, with a mean age of 36 years and nerve defect of 18.7 mm. The rate of recovery of sensory function at 12 months was 75% (36/49) for the artificial nerve conduit group and 73.7% (28/38) in the autologous nerve group. No serious adverse events directly associated with use of the artificial nerve conduit were identified. ConclusionsThe treatment of nerve defects ≤30 mm using artificial collagen nerve conduits was not inferior to treatment using autologous nerve grafts. Based on our data, the new artificial collagen nerve conduit can provide an alternative to autologous nerve for the treatment of peripheral nerve defects.

Sustained delivery of glial cell-derived neurotrophic factors in collagen conduits for facial nerve regeneration

Facial nerve injury caused by traffic accidents or operations may reduce the quality of life in patients, and recovery following the injury presents unique clinical challenges. Glial cell-derived neurotrophic factor (GDNF) is important in nerve regeneration; however, soluble GDNF rapidly diffuses into body fluids, making it difficult to achieve therapeutic efficacy. In this work, we developed a rat tail derived collagen conduit to connect nerve defects in a simple and safe manner. GDNF was immobilized in the collagen conduits via chemical conjugation to enable controlled release of GDNF. The GDNF delivery system prevented rapid diffusion from the site without impacting bioactivity of GDNF; degradation of the collagen conduit was inhibited owing to the chemical conjugation. The artificial nerve conduit was then used to examine facial nerve regeneration across a facial nerve defect. Following transplantation, the artificial nerve conduits degraded gradually without causing dislocations and serious inflammation, with good integration into the host tissue. Functional and histological tests indicated that the artificial nerve conduits were able to guide the axons to grow through the defect, reaching the distal stumps. The degree of nerve regeneration in the group that was treated with the artificial nerve conduit approached that of the autograft group, and exceeded that of the other conduit grafted groups. Statement of significanceIn this study, we developed artificial nerve conduits consisting of GDNF immobilized on collagen, with the aim of providing an environment for nerve regeneration. Our results show that the artificial nerve conduits guided the regeneration of axons to the distal nerve segment. GDNF was immobilized stably in the artificial nerve conduits, and therefore retained a sufficient concentration at the target site to effectively promote the regeneration process. The artificial nerve conduits exhibited good biocompatibility and facilitated nerve regeneration and functional recovery with an efficacy that was close to that of an autograft, and better than that of the other conduit grafted groups. Our approach provides an effective delivery system that overcomes the rapid diffusion of GDNF in body fluids, promoting peripheral nerve regeneration. The artificial nerve conduit therefore qualifies as a putative candidate material for the fabrication of peripheral nerve reconstruction devices.

Can nerve regeneration on an artificial nerve conduit be enhanced by ethanol-induced cervical sympathetic ganglion block?

This study aimed to determine whether nerve regeneration by means of an artificial nerve conduit is promoted by ethanol-induced cervical sympathetic ganglion block (CSGB) in a canine model. This study involved two experiments—in part I, the authors examined the effect of CSGB by ethanol injection on long-term blood flow to the orofacial region; part II involved evaluation of the effect of CSGB by ethanol injection on inferior alveolar nerve (IAN) repair using polyglycolic acid-collagen tubes. In part I, seven Beagles were administered left CSGB by injection of 99.5% ethanol under direct visualization by means of thoracotomy, and changes in oral mucosal blood flow in the mental region and nasal skin temperature were evaluated. The increase in blood flow on the left side lasted for 7 weeks, while the increase in average skin temperature lasted 10 weeks on the left side and 3 weeks on the right. In part II, fourteen Beagles were each implanted with a polyglycolic acid-collagen tube across a 10-mm gap in the left IAN. A week after surgery, seven of these dogs were administered CSGB by injection of ethanol. Electrophysiological findings at 3 months after surgery revealed significantly higher sensory nerve conduction velocity and recovery index (ratio of left and right IAN peak amplitudes) after nerve regeneration in the reconstruction+CSGB group than in the reconstruction-only group. Myelinated axons in the reconstruction+CSGB group were greater in diameter than those in the reconstruction-only group. Administration of CSGB with ethanol resulted in improved nerve regeneration in some IAN defects. However, CSGB has several physiological effects, one of which could possibly be the long-term increase in adjacent blood flow.

Efect of longitudinally oriented collagen conduit combined with nerve growth factor on nerve regeneration after dog sciatic nerve injury.

The research on artificial nerve conduits has become a focus of study in peripheral nerve reconstruction so as a possible replacement for the treatment of autologous nerve grafts in clinics. In this study, we used longitudinally oriented collagen conduit (LOCC) combined with nerve growth factor (NGF) to reconstruct long distance of sciatic nerve defects (35 mm) in adult dog model. The long term follow-up evaluation demonstrated that the LOCC/NGF conduit allowed functional and morphological nerve regeneration at the transection site of the injured sciatic nerve. Furthermore, the functional study confirmed that when NGF was loaded onto LOCC it promoted a better recovery of regenerated axons than LOCC alone. The gastrocnemius muscle mass in the LOCC/NGF group was significantly greater than in the LOCC alone group. The results indicated that when LOCC conduit combined with NGF it would provide a preferential environment for sciatic nerve regeneration. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2131-2139, 2018.

Recent medical techniques for peripheral nerve repair: Clinico-physiological advantages of artificial nerve guidance conduits

This review outlines advanced methods for reconstructing injured peripheral nerve fibers, applying a technology of nerve tubulization with nerve guidance conduits (NGCs), and discusses fundamental and applied prospects for further development of clinical and technological studies to solve this medical problem in young and elderly patients. The current neurosurgical practice includes manipulations on nerve fibers, matching and suturing nerve fiber ends (however, it is important to avoid any tension in the zone of diastasis for a successful nerve regeneration), as well as on allo/autologous nerve grafts. Unfortunately, these therapies are not always implementable in some clinical situations due to certain limitations and their association with a potential risk of postoperative complications. Implanting artificial nerve conduits is an alternative reconstructive technique to promote physiological nerve regeneration. The article describes different engineering constructions derived from various materials, which are now either commercially available or undergoing preclinical and clinical studies. The review underlines the necessity of a further scientific search for new materials and polymers, as well as for novel technologies for fabricating artificial nerve conduits suitable for clinical medicine and rehabilitation.

Tissue engineering with peripheral blood-derived mesenchymal stem cells promotes the regeneration of injured peripheral nerves

Peripheral nerve injury repair can be enhanced by Schwann cell (SC) transplantation, but clinical applications are limited by the lack of a cell source. Thus, alternative systems for generating SCs are desired. Herein, we found the peripheral blood-derived mesenchymal stem cells (PBMSCs) could be induced into SC like cells with expressing SC-specific markers (S100, P75NTR and CNPase) and functional factors (NGF, NT-3, c-Fos, and Krox20). When the induced PBMSCs (iPBMSCs) were transplanted into crushed rat sciatic nerves, they functioned as SCs by wrapping the injured axons and expressing myelin specific marker of MBP. Furthermore, iPBMSCs seeded in an artificial nerve conduit to bridge a 10-mm defect in a sciatic nerve achieved significant nerve regeneration outcomes, including axonal regeneration and remyelination, nerve conduction recovery, and restoration of motor function, and attenuated myoatrophy and neuromuscular junction degeneration in the target muscle. Overall, the data from this study indicated that PBMSCs can transdifferentiate towards SC-like cells and have potential as grafting cells for nerve tissue engineering.

The clinical effect of the application of small diameter artificial nerve conduit on preventing neuropathic pain after crush injury of the digital nerve

Objective To observe the clinical effect of the application of small diameter artificial nerve conduit on preventing and reducing the occurrence of neuropathic pain after crush injury of the digital nerve. Methods From January 2015 to June 2016, 37 patients (50 digits) diagnosed with crush injury of the digital nerve were randomly divided into artificial nerve group and control group. There were 19 patients (25 digits) in the experimental group and 18 patients (25 digits) in the control group. Both groups underwent surgical debridement and digital nerve repair by the same surgeon, and were followed up and evaluated at 2 weeks, 6 weeks, 3 months and 6 months after the surgery. Every patient was assessed with visual analogue scale (VAS) for the degree of neuropathic pain. Results In the artificial nerve experimental group, there were 2 patients (2 digits) with neuropathic pain symptoms at the peak 2 weeks after the operation which significantly relieved at 6 weeks. In the control group, there were 5 patients (8 digits) of neuropathic pain symptoms at the peak from 2 to 6 weeks which significantly relieved within 3 months after the operation. Statistics analysis indicated that patients in the artificial nerve group had less neuropathic pain than the control group. The degree of pain was relieved and the duration was shortened significantly. Conclusion The small diameter artificial nerve conduit can effectively protect the digital nerve subjected to crush injury, prevent adhesion of the impaired nerve and its surrounding tissue, reduce compression of the scar tissue, and relieve the degree of pain and decrease the incidence of neuropathic pain. Key words: Hand injuries; Treatment outcome; Artificial nerve canal; Neuropathic pain

Electrospun nanofiber sheets incorporating methylcobalamin promote nerve regeneration and functional recovery in a rat sciatic nerve crush injury model.

Methylcobalamin (MeCbl) is a vitamin B12 analog and we previously reported its effectiveness in axonal outgrowth of neurons and differentiation of Schwann cells both in vitro and in vivo. Here we estimated the effect of local administered MeCbl with an electrospun nanofiber sheet on peripheral nerve injury. Local administration of MeCbl promoted functional recovery in a rat sciatic nerve crush injury model. These sheets are useful for nerve injury in continuity differently from artificial nerve conduits, which are useful only for nerve defects. We believe that the findings of this study are relevant to the scope of your journal and will be of interest to its readership.

Effects of nerve cells and adhesion molecules on nerve conduit for peripheral nerve regeneration.

BackgroundFor peripheral nerve regeneration, recent attentions have been paid to the nerve conduits made by tissue-engineering technique. Three major elements of tissue-engineering are cells, molecules, and scaffolds.MethodsIn this study, the attachments of nerve cells, including Schwann cells, on the nerve conduit and the effects of both growth factor and adhesion molecule on these attachments were investigated.ResultsThe attachment of rapidly-proliferating cells, C6 cells and HS683 cells, on nerve conduit was better than that of slowly-proliferating cells, PC12 cells and Schwann cells, however, the treatment of nerve growth factor improved the attachment of slowly-proliferating cells. In addition, the attachment of Schwann cells on nerve conduit coated with fibronectin was as good as that of Schwann cells treated with glial cell line-derived neurotrophic factor (GDNF).ConclusionsGrowth factor changes nerve cell morphology and affects cell cycle time. And nerve growth factor or fibronectin treatment is indispensable for Schwann cell to be used for implantation in artificial nerve conduits.

The modification research of bionic silk fibroin nerve guidance conduits by silk sericin

Objective To explore the modification of bionic silk fibroin nerve conduits (SF-NCs) by silk sericin. Methods The innovative SS/SF blended-NCs was fabricated by a vertical sequential cooling thermal induced phase separation (TIPS) processing with SF solution added sericin in proportion, its morphology was observed by Scanning electron microscopy (SEM), X-ray diffraction (XRD) and infrared spectroscopy (FTIR) were used to detect its internal molecular structure. MTT assay was used to quantitatively analyzed the PC12 cells viability co-cultured with the innovative SS/SF-NCs, SEM was used to observe the adhesion and morphology of PC12 cells seeded into the innovative SS/SF, PC12 cells were used to assess the NGF bioactivity released from the SS/SF. Results The SEM results showed that the new fabricated SS/SF-NCs had linearly oriented lamellar-like multiple-channel which distributed evenly, got great changes on the channel microstructure and their mechanical properties had been greatly improved, compared to SF-NCs. The XRD and FTIR results showed that the SS/SF-NCs had the similar internal molecular structure with natural silk. The spaces between parallel lamellar-like channels, porosities and compressive strengths of the SS/SF-NCs decreased with decreasing Sequential freezing temperature. MTT assay results showed that the viability of PC12 cell was better than the control group (P < 0.05). The SEM observation indicated that PC12 cells showed good adhesion and differentiation with neuritis outgrowth during the period of co-culture with the SS/SF-NCs. NGF release from the innovative SS/SF-NCs was prolonged over 4 weeks, and remained bioactive. Conclusion The new fabricated SS/SF-NCs modified though silk sericin, which was highly bionic the structure of peripheral nerve fasciculus, had excellent mechanical properties and could be used as another alternative of artificial nerve conduits. Key words: Nerve guidance conduits (NCs); Silk sericin/silk fibroin (SS/SF) blended; Bionic; Modification; Peripheral nerve

Facial-nerve regeneration ability of a hybrid artificial nerve conduit containing uncultured adipose-derived stromal vascular fraction: An experimental study.

This study investigated the potential of uncultured-stromal-vascular-fraction (SVF) cells in promoting facial nerve regeneration in a rat model. A 7-mm nerve defect was created in the buccal branch of facial nerve in five groups of Lewis rats (total n = 30, n = 6 per group). A silicone tube, infused with syngeneic uncultured-SVF was implanted into the facial nerve defect. Groups 1-3 received 1 × 103 , 1 × 105 , and 1 × 107 cells, and regenerated nerves were examined at 13 weeks after the surgery. The findings were compared to the autograft and collagen-alone groups with facial palsy score (FPS), the number of myelinated fibers, fiber diameter, axon diameter, myelin thickness, and g ratio. There was no significant difference in FPS between the autograft and 1 × 105 -cell groups at 13 weeks after surgery, and FPS values of these two groups were significantly higher than those of the other three groups (P < 0.01). Axon diameter significantly increased in the 1 × 105 -cell group compared with the 1 × 103 - (P < 0.05) and 1 × 107 -cell groups (P < 0.01). Myelin thickness was found to be the highest in the autograft group, followed by the 1 × 105 -, 1 × 103 -, 1 × 107 -cell, and negative control groups, and there were significant differences among all groups (P < 0.01). The infusion of uncultured-SVF into the artificial nerve conduit promoted optimal nerve regeneration that was significantly better than nerve conduit alone. © 2016 Wiley Periodicals, Inc. Microsurgery 37:808-818, 2017.

Cell compatible encapsulation of filaments into 3D hydrogels

Tissue engineering scaffolds for nerve regeneration, or artificial nerve conduits, are particularly challenging due to the high level of complexity the structure of the nerve presents. The list of requirements for artificial nerve conduits is long and includes the ability to physically guide nerve growth using physical and chemical cues as well as electrical stimulation. Combining these characteristics into a conduit, while maintaining biocompatibility and biodegradability, has not been satisfactorily achieved by currently employed fabrication techniques. Here we present a method combining pultrusion and wet-spinning techniques facilitating incorporation of pre-formed filaments into ionically crosslinkable hydrogels. This new biofabrication technique allows the incorporation of conducting or drug-laden filaments, controlled guidance channels and living cells into hydrogels, creating new improved conduit designs.

Evaluation of artificial nerve conduit and autografts in peripheral nerve repair in the rat model of sciatic nerve injury

Objective: To investigate the therapeutic effect of artificial nerve conduit in the sciatic nerve injury and repair in the rat model.Methods: A total of 60 adult male Sprague Dawley rats were evenly randomized into five groups to build the model of sciatic nerve injury and perform the injury repair experiment. The five groups were: group A which was treated with artificial nerve conduit, group B which was treated with common carotid artery (CCA) autograft, group C which was treated with sciatic nerve autograft, group D which was treated with sham operation, and group E as the normal control. The injury was repaired by direct coaptation of the nerve ends. Postoperatively, the rats’ behavior, motor nerve conduction velocity (MNCV), incubation period, amplitude, remaining rate of wet weight of the gastrocnemius muscle, the diameter and section area of the gastrocnemius cell, and the histological changes were assessed. The results were analyzed by one-way ANOVA and two-way ANOVA.Results: Twelve days postoperatively, 36 rats in groups A, B, and C presented with denervated adermotrophia on the injured ankle. The electrophysiological indicators in groups D and E were constant and similar. The values of MNCV and amplitude were group C > group A > group B, with an increasing tendency. The values of the incubation period were group C < group A < group B with statistical difference (p < 0.05) and showed a decreasing tendency. The wet gastrocnemius muscle in groups D and E showed plump morphology with luster and elasticity. Groups A and C had similar atrophic gastrocnemius muscles and reduced flexibility while the phenomena were more severe in group B. Progressive decrease of the cell diameter and sectional area was observed in groups A, B, and C. The adhesion between the sciatic nerve and the surrounding area in groups A, B, and C had statistical significance (P < 0.05), with group B the most serious.Conclusions: The results suggest that artificial nerve conduit facilitated functional and morphological regeneration of the nerve. It seemed more effective than CCA but inferior to sciatic nerve autograft in repairing sciatic nerve injury in the rat model.

Effect of polycaprolactone/collagen/hUCS microfiber nerve conduit on facial nerve regeneration

Nerve conduits have been used to bridge nerve gaps without the donor site morbidity associated with nerve grafting. To fabricate artificial nerve conduits, various biological, synthetic, and natural materials have been applied. In this study, we suggest a new fibrous nerve conduit consisting of PCL microfibers supplemented with collagen and human umbilical cord serum (hUCS). The proposed PCL-based nerve conduit exhibited significantly higher bioactivities in vitro and in vivo, compared to pure PCL and PCL/collagen fibrous conduits. Based on these results, we believe that the PCL/collagen/hUCS fibrous conduit provides more favorable micro-environmental conditions for facial nerve (FN) regeneration and has more therapeutic potential for the regeneration of FN transectional damage than the autograft technique.

Effect of Artificial Nerve Conduit Vascularization on Peripheral Nerve in a Necrotic Bed.

Several types of artificial nerve conduit have been used for bridging peripheral nerve gaps as an alternative to autologous nerves. However, their efficacy in repairing nerve injuries accompanied by surrounding tissue damage remains unclear. We fabricated a novel nerve conduit vascularized by superficial inferior epigastric (SIE) vessels and evaluated whether it could promote axonal regeneration in a necrotic bed. A 15-mm nerve conduit was implanted beneath the SIE vessels in the groin of a rat to supply it with blood vessels 2 weeks before nerve reconstruction. We removed a 13-mm segment of the sciatic nerve and then pressed a heated iron against the dorsal thigh muscle to produce a burn. The defects were immediately repaired with an autograft (n = 10), nerve conduit graft (n = 8), or vascularized nerve conduit graft (n = 8). Recovery of motor function was examined for 18 weeks after surgery. The regenerated nerves were electrophysiologically and histologically evaluated. The vascularity of the nerve conduit implanted beneath the SIE vessels was confirmed histologically 2 weeks after implantation. Between 14 and 18 weeks after surgery, motor function of the vascularized conduit group was significantly better than that of the nonvascularized conduit group. Electrophysiological and histological evaluations revealed that although the improvement did not reach the level of reinnervation achieved by an autograft, the vascularized nerve conduit improved axonal regeneration more than did the conduit alone. Vascularization of artificial nerve conduits accelerated peripheral nerve regeneration, but further research is required to improve the quality of nerve regeneration.

Effectively Axonal-supercharged Interpositional Jump-Graft with an Artificial Nerve Conduit for Rat Facial Nerve Paralysis.

Interpositional jump graft (IPJG) is a nerve graft axonally supercharged from the hypoglossal nerve. However, for using the technique, an autologous nerve, which should contain the great auricular and sural nerves, must be obtained. Depending on the donor site, unavoidable issues such as nerve disorders and postoperative scarring may appear. To reduce the issues, in this study, the authors developed an end-to-side neurorrhaphy technique with the recipient nerve and an artificial nerve conduit and investigated the efficacy of an IPJG with an artificial nerve conduit in a rat facial nerve paresis model. A ligature clip was used to crush the facial nerve trunk, thereby creating a partial facial nerve paresis model. An artificial nerve conduit was then prepared with a 10-mm-long silicone tube containing 10 μL type I collagen and used to create an IPJG between the facial nerve trunk and the hypoglossal nerve (the silicone tube group). Thirteen weeks after the surgery, the outcome was histologically and physiologically compared with conventional IPJG with autograft using the great auricular nerve. Retrograde tracer test confirmed a double innervation by the facial and hypoglossal nerve nuclei. In the autograft and silicone tube groups, the regeneration of myelinated axons was observed. In this study, the authors successfully developed an end-to-side neurorrhaphy technique with the recipient nerve and an artificial nerve conduit, and revealed that an IPJG in the conduit was effective in the rat facial nerve paresis model.

Functional recovery after implantation of artificial nerve grafts in the rat- a systematic review

PurposeThe aim of this study was to compare functional data of different nerve-gap bridging materials evaluated in rat experiments by means of a systematic review.Materials and methodsA systematic review was conducted, searching MEDLINE, HTS and CENTRAL to identify all trials evaluating functional recovery of artificial nerve conduits in the rat model.ResultsThere was a trend towards a favourable outcome of conduits coated with Schwann-cells compared to the plain synthetics. Histomorphometry, electrophysiology and muscle-weight correlated poorly with functional outcome.ConclusionSchwann-cell coated conduits showed promising results concerning functional recovery. Further standardization in outcome reporting is encouraged.

Enhancement of primary neuronal cell proliferation using printing-transferred carbon nanotube sheets.

Artificial nerve guidance conduits (aNGCs) prepared from polymer scaffolds and carbon nanotubes (CNTs) possess unique chemical and physical properties, and have been widely used in preclinical trials to promote neuronal differentiation and growth. However, there have been only a few reports on the clinical applicability of CNT sheets for proliferation of primary neuronal cells due to safety concerns. The present study assesses the ability and potential applicability of multiwalled CNTs (MWNTs) composited with polydimethylsiloxane (PDMS) sheets to promote and enhance the proliferation of primary neuronal cells. In this study, the aqueous MWNT dispersion was filtered, and the PDMS/MWNT sheets were prepared using a simple printing transfer method. Characterization of PDMS/MWNT sheets demonstrated their unique physical properties such as superior mechanical strength and electroconductivity when compared with PDMS sheets. The effect of the PDMS/MWNT sheets on the neural cell proliferation and cytotoxicity was evaluated using MTT and alamar blue assays. Our results indicate the viability and proliferation of primary neuronal cells and Schwann cells in PDMS/MWNT sheets increased over twice when compared with a noncoated dish that is not usual in the primary neuronal cell growth control (p < 0.05). In addition, PDMS/MWNT sheets enhanced the adhesion and viability of the cells compared with poly-l-lysine coated dishes, which are most commonly used for improving cell adherence. Additionally, the PDMS/MWNT sheets exhibited excellent biocompatibility for culturing neuronal and Schwann cells. Overall, all assessments indicate that PDMS/MWNT sheets are ideal candidates for the development of artificial nerve conduits for clinical use following peripheral nerve injury.

Biocompatibility and Efficacy of Five-Channel and Eight-Channel Crosslinked Urethane-Doped Polyester Elastomers (CUPEs) as Nerve Guidance Conduit for Reconstruction of Segmental Peripheral Nerve Defect Using Rat Model

Introduction: Peripheral nerve injury is common in clinical practice. Nerve defect is a challenging scenario. The current gold standard of managing a nerve defect is autologous nerve graft. However, due to the selection of nerve graft and donor site morbidity, artificial nerve conduits are gaining popularity. However, there are drawbacks of single hollow conduit such as lack of internal support to prevent conduit collapse and inability so as to recreate the proper native spatial arrangement of cells and extracellular matrix within the conduit. In this study, the biocompatibility and efficacy of five-channel and eight-channel Crosslinked Urethane-doped Polyester Elastomers (CUPEs) as nerve guidance conduit will be evaluated through a rat model with reconstruction of segmental peripheral nerve defect. Material and Method: Eighteen adult Sprague-Dawley rats were used. They were randomly allocated to three groups: autograft group, five-channel conduit group and eight-channel conduit group with each consisted of six rats. A 10mm nerve defects were created at the right sciatic nerve. They were bridged with reverse autograft, 5-channel conduit and 8-channel conduit. After eight weeks the rats were euthanized and the reconstructed nerves were harvested for histomorphometric analysis. Result: All conduits showed regenerated nerve tissue inside. There was no collapse of the conduits. There were no severe tissue reaction or scarring near the reconstructed nerve. No neuroma was formed. Histomorphometric analysis showed nerve regeneration was enhanced with increasing number of channels inside conduit. There was overall drop in fiber density between proximal and distal segment among all groups. Conclusion: CUPE nerve guidance conduit is biocompatible and shows good nerve regeneration in reconstructing nerve defect.

Nerve conduits for peripheral nerve surgery.

Autologous nerve grafts are the current criterion standard for repair of peripheral nerve injuries when the transected nerve ends are not amenable to primary end-to-end tensionless neurorrhaphy. However, donor-site morbidities such as neuroma formation and permanent loss of function have led to tremendous interest in developing an alternative to this technique. Artificial nerve conduits have therefore emerged as an alternative to autologous nerve grafting for the repair of short peripheral nerve defects of less than 30 mm; however, they do not yet surpass autologous nerve grafts clinically. A thorough understanding of the complex biological reactions that take place during peripheral nerve regeneration will allow researchers to develop a nerve conduit with physical and biological properties similar to those of an autologous nerve graft that supports regeneration over long nerve gaps and in large-diameter nerves. In this article, the authors assess the currently available nerve conduits, summarize research in the field of developing these conduits, and establish areas within this field in which further research would prove most beneficial.