Peripheral Nerve Injury Model Research Articles

Muscle spindle reinnervation using transplanted embryonic dorsal root ganglion cells after peripheral nerve transection in rats

ObjectivesMuscle spindles are proprioceptive receptors in the skeletal muscle. Peripheral nerve injury results in a decreased number of muscle spindles and their morphologic deterioration. However, the muscle spindles recover when skeletal muscles are reinnervated with surgical procedures, such as nerve suture or nerve transfer. Morphological changes in muscle spindles by cell transplantation procedure have not been reported so far. Therefore, we hypothesized that transplantation of embryonic sensory neurons may improve sensory neurons in the skeletal muscle and reinnervate the muscle spindles.Materials and methodsWe collected sensory neurons from dorsal root ganglions of 14‐day‐old rat embryos and prepared a rat model of peripheral nerve injury by performing sciatic nerve transection and allowing for a period of one week before which we performed the cell transplantations. Six months later, the morphological changes of muscle spindles in the cell transplantation group were compared with the naïve control and surgical control groups.ResultsOur results demonstrated that transplantation of embryonic dorsal root ganglion cells induced regeneration of sensory nerve fibre and reinnervation of muscle spindles in the skeletal muscle. Moreover, calbindin D‐28k immunoreactivity in intrafusal muscle fibres was maintained for six months after denervation in the cell transplantation group, whereas it disappeared in the surgical control group.ConclusionsCell transplantation therapies could serve as selective targets to modulate mechanosensory function in the skeletal muscle.

New basic insights on the potential of a chitosan-based medical device for improving functional recovery after radical prostatectomy.

To evaluate: (i) the neuro-regenerative potential of chitosan membrane (CS-Me) on acutely axotomised autonomic neurones in vitro; (ii) to exclude the possibility that a pro-regenerative biomaterial could interfere with the proliferation activity of prostate cancer cell lines; (iii) to provide an in vivo proof of the biocompatibility and regeneration promoting effect of CS-Me in a standardised rat model of peripheral nerve injury and repair; (iv) finally, to evaluate the tissue reaction induced by the degrading material; as previous studies have shown promising effects of CS-Me for protection of the neurovascular bundles for potency recovery in patients that undergo nerve-sparing radical prostatectomy (RP). Addressing aim (i), the neuro-regenerative potential, organotypic cultures derived from primary sympathetic ganglia were cultured on CS-Me over 3days and neurite extension and axonal sprouting were evaluated. Addressing aim (ii), effects of CS on cancer cells, different human prostate cancer cell lines (PC3, DU-145, LN-Cap) were seeded on CS-coated plates or cultured in the presence of CS-Me dissolution products. Addressing aims (iii) and (iv), functional recovery of peripheral nerve fibres and tissue reaction with the biomaterial, CS-Me and CS nerve guides were used to repair a median nerve injury in the rat. Functional recovery was evaluated during the post-recovery time by the behavioural grasping test. CS-Me significantly stimulated axon elongation from autonomic ganglia in comparison to control conditions in organotypic three-dimensional cultures. CS coating, as well as the dissolution products of CS-Me, led to a significantly lower proliferation rate of prostate cancer cell lines in vitro. Tissue reaction towards CS-Me and standard CS nerve guides was similar in the rat median nerve model, as was the outcome of nerve fibre regeneration and functional recovery. The results of this study provide the first experimental evidence in support of the clinical safety of CS-Me and of their postulated effectiveness for improving functional recovery after RP. The presented results are coherent in demonstrating that acutely axotomised autonomic neurones show increased neurite outgrowth on CS-Me substrate, whilst the same substrate reduces prostate cancer cell line proliferation in vitro. Furthermore, CS-Me do not demonstrate any disadvantage for peripheral nerve repair in a standard animal model.

Therapeutic benefits of maintaining mitochondrial integrity and calcium homeostasis by forced expression of Hsp27 in chemotherapy-induced peripheral neuropathy

BackgroundVincristine, a widely used antineoplastic agent, is known to be neurotoxic and to lead to chemotherapy-induced peripheral neuropathy (CIPN), which is characterized by nerve damage. Growing evidence suggests that disruption of intracellular calcium homeostasis in peripheral neurons contributes largely to the pathological conditions of CIPN. Our previous study showed that forced expression of a peripheral nerve injury-induced small heat shock protein (Hsp), Hsp27, accelerates axon regeneration and functional recovery. In the current study, we examined whether neuronal expression of human Hsp27 (hHsp27) can prevent the inhibitory effects of vincristine in two mouse models of peripheral nerve injury, namely, sciatic nerve crush and CIPN. MethodsThe protective effects of hHsp27 against vincristine were examined in mouse models of both sciatic nerve crush and CIPN using multiple approaches, including animal behavioral tests, histology, electrophysiology, transmission electron microscopy and calcium imaging. ResultsVincristine delayed functional recovery in littermate mice; however, hHsp27 Tg mice were unaffected after vincristine treatment and sciatic nerve crush. In CIPN mice, hHsp27 protected against vincristine-induced mechanical and cold allodynia by preventing axonal degeneration, demyelination, mitochondrial dysfunction, and apoptosis. Strikingly, vincristine-induced calcium influx was markedly attenuated in sensory neurons of hHsp27 Tg mice. ConclusionsOur findings suggest that preserving myelin and mitochondrial integrity as well as maintaining intracellular calcium homeostasis is beneficial for preventing CIPN, and these findings shed new light on the development of anti-CIPN drugs.

Neuroprotective effects of neurotropin in a mouse model of hypoxic-ischemic brain injury.

Ischemic-hypoxic insult leads to detrimental effects on multiple organs. The brain is especially vulnerable, and it is hard to regenerate once damaged. Currently, therapeutic options are very limited. Previous studies have reported neuroprotective effects of neurotropin, a non-protein extract derived from the inflamed skin of rabbits inoculated with vaccinia virus, using a murine model of peripheral nerve injury and cultured cell lines. However, whether neurotropin might have protective effects against brain injuries remains unclear. We, therefore, investigated the neuroprotective effect of neurotropin and possible underlying mechanisms, using a mouse model of hypoxic-ischemic brain injury. Hypoxic-ischemic brain injury was induced via a combination of the left common carotid artery occlusion and exposure to hypoxic environment (8% oxygen) in adult male C57BL/6 mice. Immediately following induction of hypoxia-ischemia, mice received either saline or 2.4 units of neurotropin. The survival rate, neurological function, infarct volume, and expression of inflammatory cytokines were evaluated. Compared to the control group, the neurotropin group exhibited a significantly higher survival rate (100% vs. 62.5%, p < 0.05) and lower neurological deficit scores (1; 0-2 vs. 3; 0-5, median; range, p < 0.05) after the hypoxic-ischemic insult. The administration of neurotropin also reduced infarct volume (18.3 ± 5.1% vs. 38.3 ± 7.2%, p < 0.05) and mRNA expression of pro-inflammatory cytokines. The post-treatment with neurotropin improved survival and neurological outcomes after hypoxic-ischemic insult. Our results indicate that neurotropin has neuroprotective effects against hypoxic-ischemic brain injury by suppressing pro-inflammatory cytokines.

Morphological and functional evaluation of the effect of novel pyrimidine derivatives on regeneration of the sciatic nerve in rats

Two novel pyrimidine derivatives, RG2 and RG6, were studied using a rat’s model of peripheral nerve injury. Toe-spreading reflex and skin sensitivity to pinch in the foot were monitored to follow recovery of motor and sensory functions in the treated animals. The remyelation rate in the distal segment of the damaged nerve was also studied using morphological analysis of cross-sections of the nerve stained with methylene blue. The obtained data demonstrate a high stimulating effect of RG2 and RG6 on the restoration of motor and sensory functions of the sciatic nerve, as well as on the post-traumatic regeneration of myelin fibers. Possible mechanisms of the observed effects are discussed.

Chitosan-Gelatin-Polypyrrole Cryogel Matrix for Stem Cell Differentiation into Neural Lineage and Sciatic Nerve Regeneration in Peripheral Nerve Injury Model.

With the advances in tissue engineering and regenerative medicine, various approaches have been developed for peripheral nerve tissue repair and regeneration. In the current study, we have synthesized a cryogel matrix from chitosan and gelatin incorporated with polypyrrole for neural tissue regeneration. The three-dimensional (3-D) cryogel matrix was fabricated to mimic the in vivo microenvironment and analyzed for stem cell differentiation. Isolated bone marrow stem cells (BMSCs) cultured on a 3-D cryogel matrix differentiated into neural lineage on the basis of scaffold properties, in a co-culture system and by treatment with the spent media of Neuro 2a cells. To validate the cell-cell contact and BMSCs differentiation, scanning electron micrography and fluorescent imaging were done, which revealed the differentiation of the BMSCs. Immunostaining and gene expression analysis showed the BMSCs differentiation in all of the three cases studied. However, BMSCs in the co-culture system showed increased neurotransmitter levels of dopamine (34%) and acetylcholine (16%) with a respective concentration of 2.04 ± 0.03 ng/mL and 15.06 ± 0.19 pg/mL. Based on these properties, an in vivo study explored the potential of the synthesized cryogel in regeneration of a 1.5 cm nerve gap in the sciatic nerve of rats for a period of 12 weeks. The biocompatibility analysis showed that the scaffold did not induce any adverse immune response. Moreover, the walking track analysis and electrophysiological and immunostaining analyses revealed enhanced sciatic nerve regeneration in comparison to the negative control group. This study reveals the regenerative potential of the cryogel matrix for peripheral nerve regeneration.

Transdermal Delivery of 4‐Aminopyridine, a Potassium Channel Blocker, Accelerates Motor Functional Recovery with Improved Nerve Myelination and Conduction Velocity after Sciatic Nerve Crush Injury in Mice

4‐Aminopyridine (4‐AP), a broad‐spectrum potassium channel blocker and FDA‐approved drug for symptomatic treatment of multiple sclerosis, has been shown to improve neuromuscular function in patients with diverse demyelinating disorders. We recently repurposed 4‐AP and demonstrated that systemic 4‐AP administration enhances global functional recovery of the affected limb, promotes remyelination of the nerve and improves the nerve conduction velocity in a mouse model of traumatic peripheral nerve injury. However, despite its beneficial effects, the clinical ability of 4‐AP to restore function is limited because of its narrow therapeutic window, the need for frequent dosing throughout the day, and potential adverse effects. Although oral or injection routes are commonly used, the therapeutic benefits with transdermal delivery of drugs are well documented to provide a sustained circulating blood levels with enhanced patient compliance and importantly without the need for multiple daily oral dosing or injections of a drug with a short half‐life. There is no current data on the transdermal delivery of 4‐AP (plasma half‐life ~3.5 hours and the effect of therapeutic window 4–7 hours post dosing). We asked whether 4‐AP could be used as a transdermal agent with an eye towards its pharmacokinetics and effects on motor function and neuronal recovery after peripheral nerve injury. Mice were assigned to moderate sciatic nerve crush injury and the effects of acute and chronic treatments with transdermal 4‐AP and vehicle (DMSO) were investigated. Using Franz diffusion cells, the skin permeability of 4‐AP (40 mg/ml) in 0.5 mL water or DMSO was determined through mouse skin. Pharmacokinetic parameters of 4‐AP in serum were determined by HPLC method at specified time points after applying 7.5μL of 4‐AP in DMSO (10 mg/ml or 20mg/ml) to the lower back skin of anesthetized mice. 4‐AP showed similar skin permeability coefficients in water (0.014 mm/hr) and DMSO (0.011 mm/hr). The maximum concentrations of 4‐AP after 75 μg and 150 μg administrations were 6.93 μM and 9.8 μM, respectively, and the time to maximum blood concentration was 60 min for both dosages. The half‐life of 4‐AP was 171.4 min and 160.0 min for 75 μg and 150 μg administration, respectively. Importantly, while both acute and chronic 4‐AP (150 μg) treatments significantly improved sciatic function index, chronic 4‐AP‐treated mice had greater nerve conduction velocity, fewer degenerating axons and thicker myelin sheaths than vehicle‐treated controls. To the best of our knowledge, this is the first study to show that topical 4‐AP, absorbed through the skin, enhances in vivo global motor function recovery with decreased axonal degeneration and increased myelination of axons.Support or Funding InformationThis work was supported by grants from the NIH (K08 AR060164‐01A) and DOD (W81XWH‐16‐1‐0725) in addition to institutional support from the University of Rochester and Pennsylvania State University Medical Centers.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Effects of trimetazidine on nerve regeneration in a rat sciatic nerve injury model.

The aim of this study was to evaluate the efficacy of trimetazidine(TMZ) after end-to-end repair in a peripheral nerve injury model. We performed end-to-end primary repair of sciatic nerves in rats and showed TMZ's regenerative effect. For this objective 30 male Sprague Dawley albino rats were used. Surgery+water group, rats were assigned to a placebo group and were given water by oral gavage. Surgery+TMZ group, rats were given trimetazidine by oral gavage. All medications were given for 12 weeks. Motor function test was performed. Afterwards, electromyography (EMG) recording was done. Finally, blood samples were taken, the animals were euthanized andsciatic nerve was removed. The amplitudes of compound muscle action potential (CMAP) increased significantly in the Surgery+TMZ group when compared with the group that have been given Surgery+Water. Nerve growth factor (NGF) immunoexpression in the Schwann cell was significantly increased in the Surgery+TMZ group compared with the Surgery+Water group. Moreover, fibrosis score was reduced in the Surgery+TMZ group compared to the Surgery+Water group.CONCLUSİONS: In conclusion, we demonstrated the superiority of TMZ on nerve healing in our experimental study which was evaluated with comparative groups (Tab. 3, Fig. 2, Ref. 31).

Decellularized Adipose Tissue: Biochemical Composition, in vivo Analysis and Potential Clinical Applications.

Decellularized tissues are gaining popularity as scaffolds for tissue engineering; they allow cell attachment, proliferation, differentiation, and are non-immunogenic. Adipose tissue is an abundant resource that can be decellularized and converted in to a bio-scaffold. Several methods have been developed for adipose tissue decellularization, typically starting with freeze thaw cycles, followed by washes with hypotonic/hypertonic sodium chloride solution, isopropanol, detergent (SDS, SDC and Triton X-100) and trypsin digestion. After decellularization, decellularized adipose tissue (DAT) can be converted into a powder, solution, foam, or sheet to allow for convenient subcutaneous implantation or to repair external injuries. Additionally, DAT bio-ink can be used to 3D print structures that closely resemble physiological tissues and organs. Proteomic analysis of DAT reveals that it is composed of collagens (I, III, IV, VI and VII), glycosaminoglycans, laminin, elastin, and fibronectin. It has also been found to retain growth factors like VEGF and bFGF after decellularization. DAT inherently promotes adipogenesis when seeded with adipose stem cells in vitro, and when DAT is implanted subcutaneously it is capable of recruiting host stem cells and forming adipose tissue in rodents. Furthermore, DAT has promoted healing in rat models of full-thickness skin wounds and peripheral nerve injury. These findings suggest that DAT is a promising candidate for repair of soft tissue defects, and is suitable for breast reconstruction post-mastectomy, wound healing, and adipose tissue regeneration. Moreover, since DAT's form and stiffness can be altered by physicochemical manipulation, it may prove suitable for engineering of additional soft and hard tissues.

Regenerative activity of Hericium erinaceus on axonal injury model using in vitro laser microdissection technique

ABSTRACTObjective: Peripheral nerve injury (PNI) is an important global health problem. Nerve Growth Factor (NGF) plays crucial role in the survival, growth, and maintenance of various neurons in the mammalian nervous system, human included. Hericium erinaceus (HE), an edible and medicinal mushroom, has been extensively studied for its neuroprotective properties. In this study, the neuroprotective and neurotogenic effects of HE and NGF were compared on mouse PNI model by using a laser microdissection technique.Methods: Neuronal cultures were prepared from dorsal root ganglia (DRG) of 6–8 week aged mice, pretreated them with phosphate-buffered saline (PBS), NGF, HE, or the combination of NGF and HE. To model axonal injury in vitro, axons were cut (axotomy) with a microscope-controlled laser beam. Axotomized neurons were imaged under the microscope. Axotomized neurons’ survival ratios were calculated using the propidium iodide (PI), which is a red-fluorescent nuclear dye. Their axon lengths were measured using the AxioVision 4.8 software.Results: Although both HE and NGF have neuroprotective and regenerative effects on axotomized peripheral sensory neurons, HE exhibits a higher neuroprotective activity compared to the NGF. The combination of HE and NGF maximizes axonal regeneration ability of axotomized neurons.Conclusion: HE has capabilities of preventing the death of neurons and regenerating their axons in the experimental axonal injury model. Our findings provide experimental evidence that HE may serve as a neuroprotective and regenerative candidate for treating peripheral nerve injuries. Present study warrants further investigation of HE as a potential natural compound to remedy PNI.

Detection of local and remote cellular damage caused by spinal cord and peripheral nerve injury using a heat shock signaling reporter system

Spinal cord and peripheral nerve injury results in extensive damage to the locally injured cells as well as distant cells that are functionally connected to them. Both primary and secondary damage can cause a broad range of clinical abnormalities, including neuropathic pain and cognitive and memory dysfunction. However, the mechanisms underlying these abnormalities remain unclear, awaiting new methods to identify affected cells to enable examination of their molecular, cellular and physiological characteristics. Here, we report that both primary and secondary damage to cells in mouse models of spinal cord and peripheral nerve injury can be detected in vivo using a novel fluorescent reporter system based on the immediate stress response via activation of Heat Shock Factor 1. We also provide evidence for altered electrophysiological properties of reporter-positive secondarily-injured neurons. The comprehensive identification of injured, but surviving cells located both close and at distant locations from the injury site in vivo will provide a way to study their pathophysiology and possibly prevention of their further deterioration.

Evaluation of dexamethasone treated mesenchymal stem cells for recovery in neurotmesis model of peripheral nerve injury

ABSTRACTObjective: Peripheral nerve injuries comprise significant portion of the nervous system injuries. Although peripheral nerves show some capacity of regeneration after injury, the extent of regeneration is not remarkable. The present study aimes to evaluate the regeneration of transected sciatic nerve by a therapeutic value of dexamethasone (DEX) associated with cell therapy (Cell) and biodegradable membrane (Mem) in rat.Methods: Male Wistar rats (n = 42, 180-200g) were randomly divided into control (Ctrl), Membrane+ Cell, Mem, DEX, DEX+ Cell, DEX+ Mem and DEX+ Cell+ Mem groups. Functional recovery was evaluated at 2, 4, 6, 8 and 12 weeks after surgery using sciatic functional index (SFI), withdrawal reflex latency (WRL) test, electrophysiological and histological analyses.Results: The rats in the DEX+ Cell+ Mem-treated group showed a significant improvement in SFI, WRL and electrophysiological findings during the 2nd to 12th weeks after surgery. In addition, histomorphological findings showed a significant improvement in the DEX+ Cell+ Memtreated group, at 12 weeks after surgery.Discussion: Taken together, use of DEX associated with cell and biodegradable membrane could improve functional and histomorphological properties of the sciatic nerve after injury.

NGF and BDNF expression in mouse DRG after spared nerve injury

Neuropathic pain is initiated by a primary lesion in the peripheral nervous system and spoils quality of life. Neurotrophins play important roles in the development and transmission of neuropathic pain. There are conflicting reports that the dorsal root ganglion (DRG) in an injured nerve contribute to neuropathic pain, whereas several studies have highlighted the important contribution of the DRG in a non-injured nerve. Clarifying the role of neurotrophins in neuropathic pain is problematic because we cannot distinguish injured and intact neurons in most peripheral nerve injury models. In the present study, to elicit neuropathic pain, we used the spared nerve injury (SNI) model, in which injured DRG neurons are distinguishable from intact ones, and mechanical allodynia develops in the intact sural nerve skin territory. We examined nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) expression in the DRGs of SNI model mice. NGF and BDNF levels increased in the injured L3 DRG, while NGF decreased in the intact L5 DRG. These data offer a new point of view on the role of these neurotrophins in neuropathic pain induced by peripheral nerve injury.

Effect of exercise on the cell death and axonal regeneration in a rat model of peripheral nerve injury

Low intensity exercise following peripheral nerve injury promotes nerve regeneration, whereas high intensity exercise has a negative effect. Our study aimed to assess the influence of low intensity exercise on the expression of proteins related to cell death regulation and axonal regrowth. The sciatic nerves of 10-week-old male Wistar rats were crushed, using iced clips. The animals were randomized into 3 groups: injured rats not subjected to exercise (SC group) to assess spontaneous recovery; injured rats subjected to exercise by disturbance stimulator (SCex group); non-injured rats (Sham group). The animals were sacrificed at 2 or 4 weeks after injury. Immunofluorescence against BDNF, NGF, GAP 43, and Caspase-3 was performed and the expression levels of each marker were calculated per unit area. Two-way Anova for multiple comparisons with Tukey's test was used. BDNF expression was significantly increased in the SC group compared to the Sham group ( P < 0.05). NGF did not show any significant difference among the group in terms of treatment and time. GAP 43 expression was significantly decreased in the SC and SCex groups as compared to the Sham group ( P < 0.05), and 4 weeks was significantly increased ( P < 0.05). Caspase-3 expression showed an increasing trend in the SC group and increased significantly at 4 weeks ( P < 0.05). The up-regulation of BDNF following NGF during nerve regeneration suggests that cell death is observed after nerve injury, but can be reduced by exercise. At later stages after injury, trophic factors protecting cells from death are down-regulated, possibly resulting in the increased cell death. GAP43 expression increased over time in the injured rats, indicating elongation of regenerating axons. In this study, we show that low intensity exercise reduces cell death in the injured nerve and promotes elongation of regenerating axons. Our future goal is to examine the potential effect of exercise on neural plasticity.

Identification of a resilient mouse facial motoneuron population following target disconnection by injury or disease.

When nerve transection is performed on adult rodents, a substantial population of neurons survives short-term disconnection from target, and the immune system supports this neuronal survival, however long-term survival remains unknown. Understanding the effects of permanent axotomy on cell body survival is important as target disconnection is the first pathological occurrence in fatal motoneuron diseases such as amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA). The goal of this study was to determine if facial motoneurons (FMN) could survive permanent target disconnection up to 26 weeks post-operation (wpo) after facial nerve axotomy (FNA). In addition, the potentially additive effects of immunodeficiency and motoneuron disease on post-axotomy FMN survival were examined. This study included three wild type (WT) mouse strains (C57BL/6J, B6SJL, and FVB/NJ) and three experimental models (RAG-2-/-: immunodeficiency; mSOD1: ALS; Smn-/-/SMN2+/+: SMA). All animals received a unilateral FNA, and FMN survival was quantified at early and extended post-operative timepoints. In the C57BL/6J WT group, FMN survival significantly decreased at 10 wpo (55±6%), and then remained stable out to 26 wpo (47±6%). In the RAG-2-/- and mSOD1 groups, FMN death occurred much earlier at 4 wpo, and survival plateaued at approximately 50% at 10 wpo. The SMA model and other WT strains also exhibited approximately 50% FMN survival after FNA. These results indicate that immunodeficiency and motoneuron disease accelerate axotomy-induced neuron death, but do not increase total neuron death in the context of permanent target disconnection. This consistent finding of a target disconnection-resilient motoneuron population is prevalent in other peripheral nerve injury models and in neurodegenerative disease models as well. Characterization of the distinct populations of vulnerable and resilient motoneurons may reveal new therapeutic approaches for injury and disease.

Microstructure and in vivo characterization of multi-channel nerve guidance scaffolds

In a previous study, we demonstrated a novel manufacturing approach to fabricate multi-channel scaffolds (MCS) for use in spinal cord injuries (SCI). In the present study, we extended similar materials processing technology to fabricate significantly longer (5X) porous poly caprolactone (PCL) MCS and evaluated their efficacy in 1 cm sciatic peripheral nerve injury (PNI) model. Due to the increase in MCS dimensions and the challenges that may arise in a longer nerve gap model, microstructural characterization involved MCS wall permeability to assess nutrient flow, topography, and microstructural uniformity to evaluate the potential for homogeneous linear axon guidance. It was determined that the wall permeability dramatically varied from 0.02 ± 0.01 × 10−13 to 21.7 ± 11.4 × 10−13 m2 for 50% and 70% porous PCL, respectively. Using interferometry, the porous PCL surface roughness was determined to be 10.7 ± 1.2 μm, which is believed to be sufficient to promote cell integration. Using micro computed tomography, the 3D MCS microstructure was determined to be uniform over 1 cm with an open lumen volume of 44.6% ± 3.6%. In vivo implantation, in the rat sciatic nerve model, over 4 weeks, demonstrated that MCS scaffolds maintained structural integrity, were biocompatible, and supported linear axon guidance and distal end egress over 1 cm. Taken together, this study demonstrated that MCS technology previously developed for the SCI is also relevant to longer nerve gap PNI.

MG17, A Novel Triazole Derivative Abrogated Neuroinflammation and Related Neurodegenerative Symptoms in Rodents.

The objective of present study is to explore multiple effects of the compound MG17 and relate them to achieve better therapeutic potential against neuroinflammation related disorders. We examined whether our compound is acting through regulating neuroinflammatory mediators. We have done some preliminary behavioral studies to shortlist the derivatives using rodent models of peripheral nerve injury in our earlier publication and now we extended our screening studies to explore the test compounds efficacy on other related peripheral neurological disorders such as Streptozotocin- induced diabetic peripheral neuropathy (DPN) and methyl mercury (MeHg) induced neurodegeneration in rats. Pro-inflammatory cytokines interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were quantified with RT-qPCR studies and histopathology studies were performed taking tissue samples from MeHg induced neurodegeneration rats. The effect of MG17 was assessed on local and acute inflammation through carrageenan-induced rat paw edema model. We observed the reduction in nociceptive responses in DPN rats. Pain threshold was reduced greater than 50% in various pain assessment modules. Upregulated pro-inflammatory cytokines which are thought to have a prominent role in neuroinflammation was controlled near to normal level quantified by RT-PCR studies. However, MG17 was able to regulate IL-6 and TNF-α but not IL-1β. Our results clearly suggest the beneficial potential of compound MG17 through inhibition of pro-inflammatory cytokines upregulation. MG17 could be an intriguing therapeutic approach in diabetesrelated neuro-pathophysiological conditions.

Evaluation of nerve growth factor (NGF) treated mesenchymal stem cells for recovery in neurotmesis model of peripheral nerve injury

BackgroundPeripheral nerve damages are a relatively common type of the nervous system injuries. Although peripheral nerves show some capacity of regeneration after injury, the extent of regeneration is not remarkable. The present study aimed to evaluate the effect of NGF treated mesenchymal stem cells on regeneration of transected sciatic nerve. Materials and methodsIn this experimental study, forty-two male Wistar.rats (180–200 g) were randomly divided into 6 groups (n = 7) including control, Membrane + Cell (Mem + Cell), NGF group, NGF + Cell group, NGF + Mem group and NGF + Mem + Cell group. Regeneration of sciatic nerve was evaluated using behavioral analysis, electrophysiological assessment and histological examination. ResultsThe rats in the NGF + Mem + Cell group showed significant decrease in sciatic functional index (SFI) and hot water paw immersion test during the 2nd to 8th weeks after surgery. (p < 0.001). At 8 weeks after surgery, electrophysiological findings showed that amplitude increased and latency decreased significantly in NGF + Mem + Cell group (p < 0.001). Measured histological parameters showed that number of nerve fibers, number of vessels and percent of vessel area also increased significantly in NGF + Mem + Cell group (p < 0.05). ConclusionThe present study showed that NGF in accompany with mesenchymal stem cells improved electrophysiological and histological indices.

A PERIPHERAL NERVE INJURY MODEL UTILIZING A SIMPLE TISSUE SPARING APPROACH TO THE RABBIT SCIATIC NERVE

Background &amp; Aims: Peripheral nerve injury models require a reproducible surgical technique that provides a simple and extensile peripheral nerve exposure. We present a muscle sparing apprach to the sciatic nerve in a rabbit model. A combination of general anestheia, sedative and perioperative analgesics was given to minimize animal discomfort. Methods: A posterior lateral dissection of the rabbit hind leg was performed to expose the proximal sciatic nerve. This facilitated an extensile dissection of both the proximal and distal sciatic nerve. Results: The described dissection is atraumatic, bloodless, and yields minimal postoperative morbidity on the rabbit. All rabbits received standard postoperative care in compliance with all regulatory agencies. A full vetinarian staff was available to manage the animals postoperatively. Conclusion: We found that our technique is a reproducible and easy to perform surgical approach with basic surgical setup. Our animal model provides an opportunity to evaluate and study peripheral nerve injuries peripheral nerve injuries.

Different effects of dexmedetomidine and midazolam on the expression of NR2B and GABAA-α1 following peripheral nerve injury in rats.

Neuropathic pain is a complex, chronic pain condition and the treatment is a major clinical challenge. Recent studies have shown that two FDA approved drugs dexmedetomidine (DEX) and midazolam (MZL), may be useful in treating neuropathic pain, but the mechanism is not fully dementated. Here, we investigated the effects and mechanisms of DEX and MZL treatment in the peripheral nerve injury model. Intramuscular injection with DEX and MZL attenuated the development of mechanical allodynia and thermal hyperalgesia in rats with chronic constriction injury (CCI). Concurrently, the expression of NMDA receptor subunit 2B (NR2B), GABA (A) receptor subunit alpha1 (GABAA-α1), and Sonic Hedgehog (SHH) displayed different temporal patterns in the thalamus and the ipsilateral dorsal horn of the spinal cord after CCI. Such that (1) NR2B expression was decreased on day 1 and 14, whereas GABAA-α1 expression was increased on day 1 in the thalamus, and NR2B expression was decreased on day 1, whereas GABAA-α1 expression was increased on day 1 and day 30 in the ipsilateral spinal cord dorsal horn after DEX treatment. (2) NR2B expression was increased on day 1, then decreased on day 14 and returned to baseline on day30, whereas GABAA-α1 expression was no significant changes on day 1, 14, 30 in the thalamus, and NR2B expression was decreased on day 14 and 30, whereas GABAA-α1 expression was no changes on day 1 and 14 but increased on day 30 after MZL treatment. Furthermore, the mechanical allodynia was significantly attenuated after PUR administration. Meanwhile the expression of NR2B was significantly decreased, and the expression of GABAA-α1 was significantly increased, in the thalamus and in the ipsilateral spinal cord dorsal horn when detected on postoperative day 1, 7, and 14. Our findings indicate that DEX and MZL have different mechanisms in CCI rats, suggesting different strategies could be considered in managing neuropathic pain in different individuals. © 2018 IUBMB Life, 70(2):143-152, 2018.