Walking Track Analysis Research Articles

Low-Level Laser-Accelerated Peripheral Nerve Regeneration within a Reinforced Nerve Conduit across a Large Gap of the Transected Sciatic Nerve in Rats

This study proposed a novel combination of neural regeneration techniques for the repair of damaged peripheral nerves. A biodegradable nerve conduit containing genipin-cross-linked gelatin was annexed using beta-tricalcium phosphate (TCP) ceramic particles (genipin-gelatin-TCP, GGT) to bridge the transection of a 15 mm sciatic nerve in rats. Two trigger points were irradiated transcutaneously using 660 nm of gallium-aluminum arsenide phosphide (GaAlAsP) via laser diodes for 2 min daily over 10 consecutive days. Walking track analysis showed a significant improvement in sciatic functional index (SFI) (P < 0.01) and pronounced improvement in the toe spreading ability of rats undergoing laser stimulation. Electrophysiological measurements (peak amplitude and area) illustrated by compound muscle action potential (CMAP) curves demonstrated that laser stimulation significantly improved nerve function and reduced muscular atrophy. Histomorphometric assessments revealed that laser stimulation accelerated nerve regeneration over a larger area of neural tissue, resulting in axons of greater diameter and myelin sheaths of greater thickness than that observed in rats treated with nerve conduits alone. Motor function, electrophysiological reactions, muscular reinnervation, and histomorphometric assessments all demonstrate that the proposed therapy accelerated the repair of transected peripheral nerves bridged using a GGT nerve conduit.

The Protective Effects of Achyranthes bidentata Polypeptides on Rat Sciatic Nerve Crush Injury Causes Modulation of Neurotrophic Factors

Pharmacological treatment is a therapeutic approach to improving nerve regeneration and functional recovery after peripheral nerve crush injury. The objective of the present study was to investigate the effects of the polypeptides isolated from Achyranthes bidentata Blume (abbreviated as ABPP) on rat sciatic crush injury and to test the possible involvement of neurotrophic factors. After surgical crush injury, rats received daily intraperitoneal injection of 0.2ml saline containing 2mg ABPP, 1μg nerve growth factor (NGF) or no additive. The results from walking track analysis, electrophysiological assessment and histological evaluation indicated that the repair outcomes by ABPP treatment were close to those by NGF treatment, but better than those by treatment with saline alone. The quantitative real-time RT-PCR was used to monitor the mRNA expression of growth associated protein in the crush nerves and the mRNA expression of NGF, brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), tyrosine kinase (Trk)A and TrkB in the dorsal root ganglia (DRGs) at L4-L6. The mRNA expression of these genes in the crush nerve sample and DRGs sample was higher after treatment with ABPP or NGF than after treatment with saline alone. Our findings suggest that ABPP might protect peripheral nerve against crush injury through stimulating release of neurotrophic factors and the other cytokines.

Hindpaw Withdrawal from a Painful Thermal Stimulus after Sciatic Nerve Compression and Decompression in the Diabetic Rat

Although the effect of chronic compression and surgical decompression of the diabetic rat sciatic nerve has been evaluated by walking track analysis, the measurement of sensory function by response to thermal nociceptive stimulation has not been investigated. Fifteen male Wistar rats with streptozotocin-induced diabetes underwent sciatic nerve compression through a 10-mm silicone band. Five rats had histology done 60 days after confirming chronic nerve compression. Pain threshold was measured using hindlimb withdrawal times (HLWT) from a heat stimulus. After 60 days of compression, the silicone tube was removed. Five nondiabetic, nonbanded rats were used as controls. Control mean HLWT was 9.7 ± 1.5 sec. In the diabetes group (60 days of compression), mean HLWT was 23.6 ± 2.4 sec. (p < 0.001). Thirty days after removal of the silicone, mean HLWT to painful stimuli was 14.9 ± 1.5 sec. (p < 0.001). Chronic compression of the diabetic rat sciatic nerve increases (worsens) the threshold to heat (pain) perception. Decompression reverses this effect (improves nociception).

Effects of Low‐Level Laser Therapy (LLLT) and Diclofenac (Topical and Intramuscular) as Single and Combined Therapy in Experimental Model of Controlled Muscle Strain in Rats

Muscle injuries represent ca 30% of sports injuries and excessive stretching of muscle causes more than 90% of injuries. Currently the most used treatments are nonsteroidal anti-inflammatory drugs (NSAIDs), however, in last years, low-level laser therapy (LLLT) is becoming an interesting therapeutic modality. The aim of this study was to evaluate the effect of single and combined therapies (LLLT, topical application of diclofenac and intramuscular diclofenac) on functional and biochemical aspects in an experimental model of controlled muscle strain in rats. Muscle strain was induced by overloading tibialis anterior muscle of rats. Injured groups received either no treatment, or a single treatment with topical or intramuscular diclofenac (TD and ID), or LLLT (3J, 810nm, 100mW) 1h after injury. Walking track analysis was the functional outcome and biochemical analyses included mRNA expression of COX-1 and COX-2 and blood levels of prostaglandin E2 (PGE2 ). All treatments significantly decreased COX-1 and COX-2 gene expression compared with injury group (P<0.05). However, LLLT showed better effects than TD and ID regarding PGE2 levels and walking track analysis (P<0.05). We can conclude that LLLT has more efficacy than topical and intramuscular diclofenac in treatment of muscle strain injury in acute stage.

Comparison of the beneficial effect of melatonin on recovery after cut and crush sciatic nerve injury: a combined study using functional, electrophysiological, biochemical, and electron microscopic analyses

Following tissue injury, melatonin is known to reduce detrimental effects of free radicals by stimulating antioxidant enzymes and also to inhibit posttraumatic polymorphonuclear infiltration. Beneficial effects after peripheral nerve injury have been suggested, but not studied in detail. Therefore, we aimed to elucidate the effects of melatonin on the recovery of the lesioned rat sciatic nerve by means of combined analysis. A total number of 90 rats were randomly distributed into six groups: control (group 1), sham-operated (group 2), sciatic nerve cut (group 3), sciatic nerve cut + melatonin treatment (group 4), sciatic nerve crush (group 5), and sciatic nerve crush + melatonin treatment (group 6). Melatonin was administered intraperitoneally at a dose of 50mg/kg/day for 6weeks. Recovery of function was analyzed by assessment of the sciatic functional index based on walking track analysis, somatosensory evoked potentials, biochemical quantification of malondialdehyde, antioxidant enzymes levels, and ultrastructural analysis. Our data showed the beneficial effect of melatonin on sciatic nerve recovery. Rats treated with melatonin demonstrated better structural preservation of the myelin sheaths compared to the nontreated group. The biochemical analysis confirmed the beneficial effects of melatonin displaying lower lipid peroxidation and higher superoxide dismutase, catalase, and glutathione peroxidase activities in sciatic nerve samples in comparison to nontreated groups. The beneficial effects of melatonin administration on the recovery of the cut and crush injured sciatic nerve may be attributed to its antioxidant properties. Based on these investigations, we think that our data would be helpful for clinicians who deal with peripheral nerve injuries.

The research of sciatic nerve combined plastics efficiency at it’s large defect by it’s functional recovery quantification in rats in experiment

Introduction. The aim of the research was sciatic nerve functional recovery quantification at it’s large defect replacement using methods of combined plastics in rats in experiment. Materials and methods. To control sciatic nerve functional recovery “Walking track analysis” was used. Results. On the base of 3 main parameters of imprints of soles of hinder legs sciatic functional index (SFI). Conclusions. 1. The indicators of sciatic nerve functional recovery at it’s defect using combined plastics methods come nearer to results, obtained at nerve’s defect replacement using autoneuroplastics. 2. Sciatic nerve’s functional recovery level at it’s defect do not depends on the variant of combined plastics.

Effects of large‐area irradiated laser phototherapy on peripheral nerve regeneration across a large gap in a biomaterial conduit

This paper proposes a novel biodegradable nerve conduit comprising 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) cross-linked gelatin, annexed with β-tricalcium phosphate (TCP) ceramic particles (EDC-Gelatin-TCP, EGT). In this study, the EGT-implant site in rats was irradiated using a large-area 660 nm AlGaInP diode laser (50 mW) to investigate the feasibility of laser stimulation in the regeneration of a 15-mm transected sciatic nerve. The animals were divided into three groups: a sham-irradiated group (EGT/sham); an experimental group undergoing low-level laser (LLL) therapy (EGT/laser); a control group undergoing autologous nerve grafts (autografts). Twelve weeks after implantation, walking track analysis showed a significantly higher sciatic functional index (p < 0.05) and improved toe spreading development in the EGT/laser and autograft groups than in the EGT/sham group. In electrophysiological measurement, both the mean peak amplitude and the area under the compound muscle action potential curves in the EGT/laser and autograft groups showed significantly improved functional recovery than the EGT/sham group (p < 0.05). Compared with the EGT/sham group, the EGT/laser and autograft groups displayed a reduction in muscular atrophy. Histomorphometric assessments revealed that the EGT/laser group had undergone more rapid nerve regeneration than the EGT/sham group. The laser-treated group also presented greater neural tissue area as well as larger axon diameter and thicker myelin sheath than the tube group without the laser treatment, indicating improved nerve regeneration. Thus, these assessments demonstrate that LLL therapy can accelerate the repair of a transected peripheral nerve in rats after being bridged with EGT conduit.

Geldanamycin accelerated peripheral nerve regeneration in comparison to FK-506 in vivo

FK-506 accelerates nerve regeneration and improves functional recovery in vivo; its immunosuppressive properties, however, limit its clinical utility. Geldanamycin (GA), a non-immunosuppressive agent, shares a common binding target (heat shock protein 90) with FK-506 and may accelerate nerve regeneration through a similar mechanism. GA has been shown to augment neurite outgrowth in vitro but has not been tested in vivo. The current study investigated the effect of GA on the rate of axonal regeneration and functional recovery following peripheral nerve injury. In the first experiment, Thy1-GFP transgenic rats underwent serial transmuscular imaging to quantify the rate of axonal regeneration following saphenous nerve crush injury. In subsequent experiments, Lewis rats underwent tibial nerve crush or transection-and-repair injuries and were assessed for functional recovery by walking track analysis. All animals were randomized to receive daily administration of FK-506 (2mg/kg), GA (0.2mg/kg), or a control vehicle (dimethyl sulfoxide, 1mL/kg) starting 3days prior to injury. Both GA and FK-506 significantly increased the rate of axonal regeneration following crush injury in Thy1-GFP rats. In Lewis rats undergoing tibial nerve crush injury, earlier functional recovery occurred at day 5 and day 6 in animals treated with FK-506 and GA respectively, vs. day 13 for controls. Over a truncated 21-day timeframe, Lewis rats undergoing tibial nerve transection-and-repair injury and treated with FK-506 regained function at day 16, whereas those treated with GA or the control vehicle did not regain normal function. GA-treated animals, however, did exhibit significant functional improvement vs. controls. The current study demonstrated that GA accelerates axonal regeneration and enhances functional recovery in vivo. Its ability to increase the rate at which peripheral axons regenerate is comparable to that of FK-506. GA, however, did not match the performance of FK-506 in injury models where Wallerian degeneration (WD) is ongoing in the distal stump. This provides evidence that FK-506 accelerates axonal regeneration through two parallel mechanisms: the first being its well-established effect on neurons; the second is likely a newly described, as-yet poorly defined mechanism that affects WD. Finally, given the decrease in observed toxicity with GA administration, it might be a suitable non-immunosuppressive alternative to FK-506 for accelerating peripheral nerve regeneration in cases of clinical nerve injury.

Vascular endothelial growth factor-loaded poly(lactic-co -glycolic acid) microspheres-induced lateral axonal sprouting into the vein graft bridging two healthy nerves: Nerve graft prefabrication using controlled release system

The most commonly used surgical technique for repairing segmental nerve defects is autogenous nerve grafting; however, this method causes donor site morbidity. In this study, we sought to produce prefabricated nerve grafts that can serve as a conduit instead of autologous nerve using a controlled release system created with vascular endothelial growth factor (VEGF)-loaded poly(lactic-co-glycolic acid) (PLGA) microspheres. The study was performed in vitro and in vivo. For the in vitro studies, VEGF-loaded PLGA microspheres were prepared. Thirty rats were used for the in vivo studies. Vein grafts were sutured between the tibial and peroneal nerves in all animals. Three groups were created, and an epineural window, partial incision, and microsphere application were performed, respectively. Walking track analysis, morphologic, and electron microscopic assessment were performed at the end of the eight weeks. Microspheres were produced in spherical shapes as required. Controlled release of VEGF was achieved during a 30-days period. Although signs of nerve injury occurred initially in the partial incision groups according to the indexes of peroneal and tibial function, it improved gradually. The index values were not affected in the other groups. There were many myelinated fibers with large diameters in the partial incision and controlled release groups, while a few myelinated fibers that passed through vein graft in the epineural window group. Thereby, prefabrication was carried out for the second and third groups. It was demonstrated that nerve graft can be prefabricated by the controlled delivery of VEGF.

Assisted peripheral nerve recovery by KMUP-1, an activator of large-conductance Ca2+-activated potassium channel, in a rat model of sciatic nerve crush injury

Axonal regeneration in peripheral nerves after injury is a complicated process. Numerous cytokines, growth factors, channels, kinases, and receptors are involved, and matrix metalloproteinase-9 (MMP-9) has been implicated in the pathogenesis subsequent to nerve injury. In this study, the effect of KMUP-1, an activator of large-conductance Ca(2+)-activated potassium channel, on functional recovery, myelinated axon growth, and immunoreactivity of MMP-9 was evaluated in rats subjected to sciatic nerve crush injury. A total of 144 male Sprague-Dawley rats were divided into the following six groups (n = 24/group): group 1, sham-operated; group 2, sciatic nerve injury without treatment; group 3, injured and vehicle-treated; group 4, injured and treated with 1 mM KMUP-1 by topical application; group 5, injured and treated with 10 mM KMUP-1; group 6, injured and treated with 50 mM KMUP-1. Functional recovery was evaluated using walking track analysis at 1, 2, 3, and 4 weeks (n = 6/group at each time point) after injury. In addition, the number of myelinated axons and MMP-9 in the nerve was also examined. Animals subjected to sciatic nerve crush injury had decreased motor function, a reduced number of myelinated axons, and increased MMP-9 in the nerve. Treatment with KMUP-1 concentration-dependently improved functional recovery, increased the number of myelinated axons, and decreased MMP-9. These results suggest that KMUP-1 may be a novel agent for assisting peripheral nerve recovery after injury. The beneficial effect is probably due to known ability of the compound in activating the nitric oxide/cGMP/protein kinase G pathway.

Regenerative effect of adipose tissue-derived stem cells transplantation using nerve conduit therapy on sciatic nerve injury in rats

This study proposed a biodegradable GGT nerve conduit containing genipin crosslinked gelatin annexed with tricalcium phosphate (TCP) ceramic particles for the regeneration of peripheral nerves. Cytotoxicity tests revealed that GGT-extracts were non-toxic and promoted proliferation and neuronal differentiation in the induction of stem cells (i-ASCs) derived from adipose tissue. Furthermore, the study confirmed the effectiveness of a GGT/i-ASCs nerve conduit as a guidance channel in the repair of a 10-mm gap in the sciatic nerve of rats. At eight weeks post-implantation, walking track analysis showed a significantly higher sciatic function index (SFI) (P < 0.05) in the GGT/i-ASC group than in the autograft group. Furthermore, the mean recovery index of compound muscle action potential (CMAP) differed significantly between GGT/i-ASCs and autograft groups (P < 0.05), both of which were significantly superior to the GGT group (P < 0.05). No severe inflammatory reaction in the peripheral nerve tissue at the site of implantation was observed in either group. Histological observation and immunohistochemistry revealed that the morphology and distribution patterns of nerve fibers in the GGT/i-ASCs nerve conduits were similar to those of the autografts. These promising results achieved through a combination of regenerative cells and GGT nerve conduits suggest the potential value in the future development of clinical applications for the treatment of peripheral nerve injury.

Efficacy of Short-Term FK506 Administration on Accelerating Nerve Regeneration

Background. The slow rate of nerve regeneration following injury can cause extended muscle denervation, leading to irreversible muscle atrophy, fibrosis, and destruction of motor endplates. The immunosuppressant FK506 (tacrolimus) has been shown to accelerate the rate of nerve regeneration and functional recovery. However, the toxic and immunosuppressive properties of FK506 make it undesirable for long-term use. Objective. To take advantage of the regeneration-enhancing effects of FK506 but avoid the potential adverse effects of long-term administration, the current study evaluates and quantifies the efficacy of short-term FK506 treatment in rat models. Methods. Clinically relevant transection and graft models were evaluated, and walking track analysis (WTA) was used to evaluate functional recovery. FK506 was administered for 5 and 10 days post transection injury and 10 and 20 days post graft injury. Both groups involving a short course were compared with the continuous administration group. Results. In the transection model, FK506 was administered for 5 and 10 days postoperatively. WTA demonstrated that 10 days of FK506 administration was sufficient to reduce functional recovery time by 29% compared with negative controls. In the graft model, FK506 was administered for 10 and 20 days postoperatively. Short treatment courses of 10 and 20 days reduced recovery time by 15% and 21%, respectively, compared with negative controls. Analysis of blood–nerve barrier (BNB) integrity demonstrated that FK506 facilitated early reconstitution of the BNB. Conclusions. The results of this study indicate that short-term FK506 delivery following nerve injury imparts a significant therapeutic effect.

Transplantation of undifferentiated bone marrow stromal cells improves sciatic nerve regeneration and functional recovery through inside-out vein graft in rats

To study the effect of undifferentiated bone marrow stromal cells (BMSCs) on peripheral nerve regeneration using a rat sciatic nerve regeneration model. In recent years, cell transplantation has become the focus of attention, and reliable outcomes have been achieved in regeneration of the sciatic nerve. Materials and methods: A 10-mm sciatic nerve defect was bridged using an inside-out vein graft (IOVG) filled with undifferentiated BMSCs (2 × 107 cells/mL). In the control group, the vein was filled with phosphate buffered saline alone. The regenerated fibers were studied 4, 8, and 12 weeks after surgery. Assessment of nerve regeneration was based on functional (walking track analysis), histomorphometric, and immunohistochemical (Schwann cell detection by S-100 expression) criteria. Results: The functional study confirmed significant recovery of regenerated axons in the IOVG/BMSC group (P < 0.05). Quantitative morphometric analyses of regenerated fibers showed that the number and diameter of myelinated fibers in the IOVG/BMSC group were significantly higher than in the control group (P < 0.05). Conclusion: This study demonstrates the potential of using undifferentiated BMSCs in peripheral nerve regeneration without limitations of donor-site morbidity associated with isolation of Schwann cells. It also reduces costs due to the simplicity of laboratory procedures compared to those for differentiated BMSCs and the reduction in the interval from tissue collection until cell injection.

Morphofunctional characterization of peripheral nerve damage and recovery in sphyngomielinase deficient mice

Mutation of the acid sphingomyelinase (ASM) gene and its reduced enzymatic activity is the main cause of the Type A Niemann-Pick disease. Recent advances demonstrated that ASM is necessary and sufficient to control the formation and release of microvesiscles containing the proinflammatory cytokine interleukin-1β (IL-1β) by glial cells [1]. Since IL-1β modulates the events caused by nerve damage and repair and seems to act as a neuro-modulator between activated glia and neurons [2], the control of its production and secretion might represent a new strategy in nerve regeneration and in the control of neuropathic pain. In this study we used a well-characterized ASM knockout mouse (ASMKO, [3]) to evaluate, through a multimodal approach, the onset and the course of the morphological and functional nerve damage and of neuropathic pain after sciatic nerve crush. Adult (1 and 5 month-old) male ASMKO and age-matched wild-type (WT) mice underwent sciatic nerve crush lesion. Nerve conduction velocity (NCV), walking track analysis followed by ultra-structural and morphometric analysis of sciatic nerves were performed to evaluate the features of nerve damage. Thermal (Plantar test) and mechanical sensitivity (Dynamic Plantar Aesthesiometer apparatus) were used to measure the severity of neuropathic pain. Moreover, the rotarod test completed the analysis as an indicator of motor impairment. One or two months after the nerve crush motor functional recovery was similar in WT and KO mice and the NCV measures performed in the sciatic nerve demonstrated a moderate and progressive improvement of nerve function. The results of the morphological examination confirmed the expected course of nerve recovery, but also demonstrated defective nerve regeneration, particularly evident in older, but already present in younger ASMKO mice. Behavioral tests suggested that the mutated phenotype in ASMKO might have an effect on the onset and development of mechanical and thermal hyperalgesia after nerve crush in both 1 - month and 5 - months - old groups. In conclusion, these data suggest a possible role for ASM-related microvesicles in nerve regeneration and suggest that targeting the IL-1β production and release may represent a new therapeutic strategy for the treatment of nerve damage and neuropathic pain.

The effect of catheter use on vein grafting of a peripheral nerve defect: an experimental study

Since vein grafts have been used in the repair of nerve defects, studies regarding this procedure have accumulated, and after coming into clinical use, it was noticed that there is a problem of collapse in the vein graft. Forty Sprague-Dawley rats were used, divided into five groups. No surgical intervention was performed in the first group. The defect was created in the sciatic nerve in Group 2 and left unrepaired. In Group 3, the defect was repaired with a nerve graft. In Group 4, the defect was repaired with a vein graft, while in Group 5, the repair was performed using a vein graft with an inserted catheter. In order to evaluate functional recovery and nerve regeneration, walking track analysis, electrophysiologic and histomorphometric analyses were done at the end of the 12th week. Although there were no functional differences between Groups 5 and 4, comparisons regarding nerve conduction velocity demonstrated that the results obtained in Group 5 were better than those in Group 4. When the number of axons on the distal part of the sciatic nerve and mid-segment of the repaired area was taken into account, no significant difference was found between Groups 3 and 5, whereas there was a significant difference between Groups 4 and 5. In our study, it was experimentally shown that the problem of collapse of a vein graft occurring after its use in the reconstruction of a nerve defect can be overcome by placing a catheter into the vein graft. Consequently, this method may eliminate the need for the use of a nerve graft in selected cases.

Omentum-Wrapped Scaffold with Longitudinally Oriented Micro-Channels Promotes Axonal Regeneration and Motor Functional Recovery in Rats

BackgroundTissue-engineered nerve scaffolds hold great potential in bridging large peripheral nerve defects. However, insufficient vascularization of nerve scaffolds limited neural tissues survival and regeneration, which hampered the successful implantation and clinical application of nerve scaffolds. The omentum possesses a high vascularization capacity and enhances regeneration and maturation of tissues and constructs to which it is applied. However, combined application of nerve scaffolds and omentum on axonal regeneration and functional recovery in the treatment of large peripheral nerve defects has rarely been investigated thus far.MethodsIn the present study, an omentum-wrapped collagen-chitosan scaffold was used to bridge a 15-mm-long sciatic nerve defect in rats. Rats that received nerve autografts or scaffolds alone were served as positive control or negative control, respectively. The axonal regeneration and functional recovery were examined by a combination of walking track analysis, electrophysiological assessment, Fluoro-Gold (FG) retrograde tracing, as well as morphometric analyses to both regenerated nerves and target muscles.FindingsThe results demonstrated that axonal regeneration and functional recovery were in the similar range between the omentum-wrapping group and the autograft group, which were significantly better than those in the scaffold alone group. Further investigation showed that the protein levels of vascular endothelial growth factor (VEGF), brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) were significantly higher in the omentum-wrapping group than those in the scaffold alone group in the early weeks after surgery.ConclusionThese findings indicate that the omentum-wrapped scaffold is capable of enhancing axonal regeneration and functional recovery, which might be served as a potent alternative to nerve autografts. The beneficial effect of omentum-wrapping on nerve regeneration might be related with the proteins produced by omentum.

The use of undifferentiated bone marrow stromal cells for sciatic nerve regeneration in rats

In recent years, cell transplantation has become a focus of attention and reliable outcomes have been achieved in regeneration of the sciatic nerve. The effect of undifferentiated bone marrow stromal cells (BMSCs) on peripheral nerve regeneration was studied using a rat sciatic nerve regeneration model. A 10-mm sciatic nerve defect was bridged using an inside-out vein graft (IOVG) filled with undifferentiated BMSCs (2×107cells/ml). In the control group, the vein was filled with phosphate buffer saline alone. The regenerated fibres were studied 4, 8 and 12 weeks after surgery. Assessment of nerve regeneration was based on functional (walking track analysis), histomorphometric and immuohistochemical (Schwann cell detection by S100 expression) criteria. The functional study confirmed significant recovery of regenerated axons in the IOVG/BMSC group (P<0.05). Quantitative morphometric analyses of regenerated fibres showed the number and diameter of myelinated fibres in the IOVG/BMSC group were significantly higher than in the control group (P<0.05). This demonstrates the potential for using undifferentiated BMSCs in peripheral nerve regeneration without the limitations of donor-site morbidity associated with isolation of Schwann cells. It also reduces costs because the interval between tissue collection and cell injection is reduced and the laboratory procedures are simpler compared to undifferentiated BMSCs.

Differentiated and undifferentiated adipose-derived stem cells improve function in rats with peripheral nerve gaps

The effect of differentiated and undifferentiated adipose-derived stem cells on the repair of peripheral nerve gaps was studied. Adipose-derived stem cells were maintained in differentiation medium for 2 weeks. The expression of Schwann cell proteins S-100, nerve growth factor receptor (NGFR) p75 and integrin β4 was examined by immunofluorescence staining and real time-polymerase chain reaction (real time-PCR) at the end of the differentiation period. A 10-mm gap on the left sciatic nerves of 20 Fischer rats was created and bridged with silicone tube (group I), silicone tube filled with collagen gel (group II), nerve graft (group III), silicone tube filled with adipose-derived stem cells (group IV) and silicone tube filled with differentiated adipose-derived stem cells (group V). In vitro, the positivity of differentiated adipose-derived stem cells for S-100, NGFR p75 and integrin β4 by immunofluorescence staining was 31%, 27% and 12%, respectively. Fold changes by real time-PCR in comparison with undifferentiated cells were 48.4, 168.7 and 284.85, respectively. In vivo, a walking track analysis did not yield any statistically significant differences after 3 months postoperatively; however, after 6 months, group IV (sciatic function index (SFI) = -49.1 ± 13.1) and V (SFI = -52.6 ± 5.7) showed significant improvement compared to other groups (I: -73.3 ± 5.07, II: -79.6 ± 12.01, III: -74.8 ± 12.89) (p < 0.05). Nerve conduction velocity after 6 months was higher in groups IV (4.44 ± 0.3 mm ms(-1)), V (4.25 ± 0.3 mm ms(-1)) and III (4 ± 0.3 mm ms(-1)) than in groups I (2.5 ± 2.25 mm ms(-1)) and II (2.35 ± 1.58 mm ms(-1)) (p > 0.05). Myelin fibre density and myelinated fibre/unmyelinated fibre ratio were significantly higher in the midnerve and the distal nerve in groups IV and V (p < 0.05). These results reveal the therapeutic potential of adipose-derived stem cells in nerve reconstruction.

Peripheral nerve repair of transplanted undifferentiated adipose tissue‐derived stem cells in a biodegradable reinforced nerve conduit

This study proposes a biodegradable nerve conduit containing genipin-cross-linked gelatin annexed with tricalcium phosphate ceramic particles (genipin-gelatin-tricalcium phosphate, GGT) in peripheral nerve regeneration. Firstly, cytotoxicity tests revealed that the GGT-extracts were not toxic, and promoted the proliferation and neuronal differentiation of adipose tissue-derived stem cells (ADSCs). Secondly, the GGT composite film effectively supported ADSCs attachment and growth. Additionally, the GGT substrate was biocompatible with the neonatal rat sciatic nerve and produced a beneficial effect on peripheral nerve repair through in vitro tissue culture. Finally, the experiments in this study confirmed the effectiveness of a GGT/ADSCs nerve conduit as a guidance channel for repairing a 10-mm gap in a rat sciatic nerve. Eight weeks after implantation, the mean recovery index of compound muscle action potentials (CMAPs) was significantly different between the GGT/ADSCs and autografts groups (p < 0.05), both of which were significantly superior to the GGT group (p < 0.05). Furthermore, walking track analysis also showed a significantly higher sciatic function index (SFI) score (p < 0.05) and better toe spreading development in the GGT/ADSCs group than in the autograft group. Histological observations and immunohistochemistry revealed that the morphology and distribution patterns of nerve fibers in the GGT/ADSCs nerve conduits were similar to those of the autografts. The GGT nerve conduit offers a better scaffold for the incorporation of seeding undifferentiated ADSCs, and opens a new avenue to replace autologous nerve grafts for the rapid regeneration of damaged peripheral nerve tissues and an improved approach to patient care.

Effect of sialodacryoadenitis virus infection on axonal regeneration

The effect of sialodacryoadenitis virus (SDAV) infection on axonal regeneration and functional recovery was investigated in male Lewis rats. Animals underwent unilateral tibial nerve transection, immediate repair, and treatment with either FK506 (treated) or control vehicle (untreated). Serial walking track analyses were performed to assess functional recovery. Nerves were harvested for morphometric analysis on postoperative day 18 after an SDAV outbreak occurred that affected the 12 experimental animals. Histomorphometry and walking track data were compared against 36 historical controls. Rats infected with SDAV demonstrated severely impaired axonal regeneration and diminished functional recovery. Total fiber counts, nerve density, and percent neural tissue were all significantly reduced in infected animals (P < 0.05). Active SDAV infection severely impaired nerve regeneration and negated the positive effect of FK506 on nerve regeneration in rats. Immunosuppressive risks must be weighed carefully against the potential neuroregenerative benefits in the treatment of peripheral nerve injuries. © 2011 Wiley‐Liss, Inc. Microsurgery, 2011.