Spinal Cord Transection In Rats Research Articles

Hierarchically Ordered Porous and High-Volume Polycaprolactone Microchannel Scaffolds Enhanced Axon Growth in Transected Spinal Cords.

The goal of this work was to design nerve guidance scaffolds with a unique architecture to maximize the open volume available for nerve growth. Polycaprolactone (PCL) was selected as the scaffold material based on its biocompatibility and month-long degradation. Yet, dense PCL does not exhibit suitable properties such as porosity, stiffness, strength, and cell adhesion to function as an effective nerve guidance scaffold. To address these shortcomings, PCL was processed using a modified salt-leaching technique to create uniquely controlled interconnected porosity. By controlling porosity, we demonstrated that the elastic modulus could be controlled between 2.09 and 182.1 MPa. In addition, introducing porosity and/or coating with fibronectin enhanced the PCL cell attachment properties. To produce PCL scaffolds with maximized open volume, porous PCL microtubes were fabricated and translated into scaffolds with 60 volume percent open volume. The scaffolds were tested in transected rat spinal cords. Linear axon growth within both the microtubes as well as the interstitial space between the tubes was observed, demonstrating that the entire open volume of the scaffold was available for nerve growth. Overall, a novel scaffold architecture and fabrication technique are presented. The scaffolds exhibit significantly higher volume than state-of-the-art scaffolds for promising spinal cord nerve repair.

Early Fesoterodine Fumarate Administration Prevents Neurogenic Detrusor Overactivity in a Spinal Cord Transected Rat Model.

BackgroundIn spinal cord injury, onset of detrusor overactivity (DO) is detrimental for quality of life (incontinence) and renal risk. Prevention has only been achieved with complex sophisticated electrical neuromodulation techniques.PurposeTo assess the efficacy of early fesoterodine fumarate (FF) administration in preventing bladder overactivity in a spinal cord transected (SCT) rat model.Methods33 Sprague-Dawley rats were allocated to 6 groups–Group 1: 3 normal controls; Group 2: 6 SCT controls; Group 3: 6 SCT rats + FF 0.18 mg/kg/d; Group 4: 6 SCT rats + FF 0.12 mg/kg/d; Group 5: 6 SCT rats + FF 0.18 mg/kg/d + 72-h wash-out period; Group 6: 6 SCT rats + FF 0.12 mg/kg/d + 72-h wash-out period. SCT was performed at T10. FF was continuously administered. Cystometry was undertaken 6 weeks after SCT in awake rats recording intermicturition pressure (IMP), baseline pressure, threshold pressure (Pthres) and maximum pressure (Pmax). Normal controls and SCT controls were initially compared using the Mann-Whitney U tests in order to confirm the SCT effect on cystometric parameters. The comparisons in cystometric and metabolic cage parameters between SCT controls and treated rats were done using post-hoc Dunn’s tests for Kruskal-Wallis analysis. Statistical testing was conducted at the two-tailed α-level of 0.05.ResultsPressure parameters were significantly higher in SCT control group compared to normal controls. Six weeks after SCT, IMP was significantly lower in low dose treated group than in SCT controls. Pmax was significantly lower in 3 treated groups compared to SCT controls. Pthres was significantly lower in full time treated groups than in SCT controls.ConclusionEarly administration of FF modulates bladder overactivity in a SCT rat model. Whereas short-term prevention has been demonstrated, the long-term should be further analyzed. Clinical application of these results should confirm this finding through randomized research protocols.

Tail Nerve Electrical Stimulation and Electro-Acupuncture Can Protect Spinal Motor Neurons and Alleviate Muscle Atrophy after Spinal Cord Transection in Rats.

Spinal cord injury (SCI) often results in death of spinal neurons and atrophy of muscles which they govern. Thus, following SCI, reorganizing the lumbar spinal sensorimotor pathways is crucial to alleviate muscle atrophy. Tail nerve electrical stimulation (TANES) has been shown to activate the central pattern generator (CPG) and improve the locomotion recovery of spinal contused rats. Electroacupuncture (EA) is a traditional Chinese medical practice which has been proven to have a neural protective effect. Here, we examined the effects of TANES and EA on lumbar motor neurons and hindlimb muscle in spinal transected rats, respectively. From the third day postsurgery, rats in the TANES group were treated 5 times a week and those in the EA group were treated once every other day. Four weeks later, both TANES and EA showed a significant impact in promoting survival of lumbar motor neurons and expression of choline acetyltransferase (ChAT) and ameliorating atrophy of hindlimb muscle after SCI. Meanwhile, the expression of neurotrophin-3 (NT-3) in the same spinal cord segment was significantly increased. These findings suggest that TANES and EA can augment the expression of NT-3 in the lumbar spinal cord that appears to protect the motor neurons as well as alleviate muscle atrophy.

The Signature of MicroRNA Dysregulation in Muscle Paralyzed by Spinal Cord Injury Includes Downregulation of MicroRNAs that Target Myostatin Signaling.

Spinal cord injury (SCI) results in muscle atrophy, reduced force generation and an oxidative-to-glycolytic fiber type shift. The mechanisms responsible for these alterations remain incompletely understood. To gain new insights regarding mechanisms involved in deterioration of muscle after SCI, global expression profiles of miRs in paralyzed gastrocnemius muscle were compared between sham-operated (Sham) and spinal cord-transected (SCI) rats. Ingenuity Pathways Analysis of the altered miRs identified signaling via insulin, IGF-1, integrins and TGF-β as being significantly enriched for target genes. By qPCR, miRs 23a, 23b, 27b, 145, and 206, were downregulated in skeletal muscle 56 days after SCI. Using FISH, miR-145, a miR not previously implicated in the function of skeletal muscle, was found to be localized to skeletal muscle fibers. One predicted target of miR-145 was Cited2, a transcriptional regulator that modulates signaling through NF-κB, Smad3 and other transcription factors. The 3’ UTR of Cited2 mRNA contained a highly conserved miR-145 seed sequence. Luciferase reporter assays confirmed that miR-145 interacts with this seed sequence. However, Cited2 protein levels were similar between Sham and SCI groups, indicating a biochemical interaction that was not involved in the context of adaptations after SCI. Taken together, the findings indicate dysregulation of several highly expressed miRs in skeletal muscle after SCI and suggest that reduced expression of miR-23a, 145 and 206 may have roles in alteration in skeletal muscle mass and insulin responsiveness in muscle paralyzed by upper motor neuron injuries.

Enhanced noradrenergic axon regeneration into schwann cell-filled PVDF-TrFE conduits after complete spinal cord transection.

Schwann cell (SC) transplantation has been utilized for spinal cord repair and demonstrated to be a promising therapeutic strategy. In this study, we investigated the feasibility of combining SC transplantation with novel conduits to bridge the completely transected adult rat spinal cord. This is the first and initial study to evaluate the potential of using a fibrous piezoelectric polyvinylidene fluoride trifluoroethylene (PVDF-TrFE) conduit with SCs for spinal cord repair. PVDF-TrFE has been shown to enhance neurite growth in vitro and peripheral nerve repair in vivo. In this study, SCs adhered and proliferated when seeded onto PVDF-TrFE scaffolds in vitro. SCs and PVDF-TrFE conduits, consisting of random or aligned fibrous inner walls, were transplanted into transected rat spinal cords for 3 weeks to examine early repair. Glial fibrillary acidic protein (GFAP)+ astrocyte processes and GFP (green fluorescent protein)-SCs were interdigitated at both rostral and caudal spinal cord/SC transplant interfaces in both types of conduits, indicative of permissivity to axon growth. More noradrenergic/DβH+ (dopamine-beta-hydroxylase) brainstem axons regenerated across the transplant when greater numbers of GFAP+ astrocyte processes were present. Aligned conduits promoted extension of DβH+ axons and GFAP+ processes farther into the transplant than random conduits. Sensory CGRP+ (calcitonin gene-related peptide) axons were present at the caudal interface. Blood vessels formed throughout the transplant in both conduits. This study demonstrates that PVDF-TrFE conduits harboring SCs are promising for spinal cord repair and deserve further investigation. Biotechnol. Bioeng. 2017;114: 444-456. © 2016 Wiley Periodicals, Inc.

Transplantation of tissue engineering neural network and formation of neuronal relay into the transected rat spinal cord.

Severe spinal cord injury (SCI) causes loss of neural connectivity and permanent functional deficits. Re-establishment of new neuronal relay circuits after SCI is therefore of paramount importance. The present study tested our hypothesis if co-culture of neurotrophin-3 (NT-3) gene-modified Schwann cells (SCs, NT-3-SCs) and TrkC (NT-3 receptor) gene-modified neural stem cells (NSCs, TrkC-NSCs) in a gelatin sponge scaffold could construct a tissue engineering neural network for re-establishing an anatomical neuronal relay after rat spinal cord transection. Eight weeks after transplantation, the neural network created a favorable microenvironment for axonal regeneration and for survival and synaptogenesis of NSC-derived neurons. Biotin conjugates of cholera toxin B subunit (b-CTB, a transneuronal tracer) was injected into the crushed sciatic nerve to label spinal cord neurons. Remarkably, not only ascending and descending nerve fibers, but also propriospinal neurons, made contacts with b-CTB positive NSC-derived neurons. Moreover, b-CTB positive NSC-derived neurons extended their axons making contacts with the motor neurons located in areas caudal to the injury/graft site of spinal cord. Further study showed that NT-3/TrkC interactions activated the PI3K/AKT/mTOR pathway and PI3K/AKT/CREB pathway affecting synaptogenesis of NSC-derived neurons. Together, our findings suggest that NT-3-mediated TrkC signaling plays an essential role in constructing a tissue engineering neural network thus representing a promising avenue for effective exogenous neuronal relay-based treatment for SCI.

Chondroitinase administration and pcDNA3.1-BDNF-BMSC transplantation promote motor functional recovery associated with NGF expression in spinal cord-transected rat.

We evaluated whether combination of chondroitinase (chABC) administration and brain-derived neurotrophic factor (BDNF)-mesenchymal stem cell (MSC) transplantation could provide an optimal effect for the treatment of spinal cord injury (SCI) subjected to complete transection. Behavioral assessments and DBA tracing were used to evaluate the effects of combination of chABC administration and BDNF-MSC transplantation on axonal regeneration and functional improvement in SCT rats. Sichuan, ChinaMethods:Bone mesenchymal stem cells (BMSCs) were cultured and overexpressed BDNF recombinant vector was constructed into MSCs, then transplanted into the impaired spinal cord, together with chABC administration. Finally, the cortical spinal tract regeneration was detected by DBA tracing at 4 weeks post operation, and the expression of nerve growth factor (NGF), BDNF, neurotrophic factor (NT)-3, NT-4, fibroblast growth factor (FGF-2)-2, B cell lymphoma 2 (BCL-2) assaciated X protein (BAX) and BCL-2 in the caudal cord tissues was assessed by reverse transcription-PCR. Animals received both BDNF-BMSC transplantation and chABC administration presented the best functional recovery and obvious axonal regeneration. Moreover, NGF expression was significantly higher than that in the other groups. Co-treated strategy could effectively promote motor functional recovery and axonal regeneration in SCT rats associated with NGF upregulation.

The Sympathetic Nervous System Mediates Functional and Robust Respiratory Recovery following Acute Cervical Spinal Cord Injury

Introduction The organization of the respiratory network has traditionally been described through descending medullary tracks. The diaphragm is innervated by the phrenic nucleus (C4-C6). However, the intercostal muscles are innervated by the intercostal motor nucleus (T1-T11) located at the thoracic spinal cord segments. Therefore, cervical spinal cord injury (SCI) can typically cause respiratory motor system dysfunction. From the literature, ventilation failure within the human lower cervical SCI population typically occurs 4.5 ± 1.2 days after injury, affecting 26.6% of patients. Also, the risk of apnea following low cervical SCI is increased during sleep. However, while intercostal muscles contribute to respiratory recovery post injury the pathways mediating this effect have never been fully elucidated. Methods Following complete C7 spinal cord transection in rats, we demonstrated the presence of intercostal-EMG activity synchronized to the inspiratory bursts of the diaphragm. We explored the anatomical, and latent, pathway that enables synchronized activation of the intercostal muscles after complete cord transection. Experimental work, in the form of bilateral dorsal/ventral rhizotomies, unilateral transection of the phrenic nerve and sympathetic chain ganglia and systemic application of salubutamol, suggested that intercostal activities is mediated through the sympathetic chain ganglion by means of connection to the ipsilateral phrenic nerve. Results In anesitised and unventilated rats, rhythmic inspiratory activity was present in the intercostal muscles following acute C7 transection and bilateral dorsal/ventral rhizotomies. This activity persisted up to five days following the initial trauma. Unilateral transection of the phrenic nerve and sympathetic chain ganglia eliminated ipsilateral intercostal motor activity. Systemic application of salubutamol (β2-agonist), not only increase intercostal activity but also restored it in transected rats which had not retained this activity following transection. Conclusions These data provide the first evidence of sympathetic nerve activity mediating synchronized and robust intercostal inspiratory muscle activity following severe, lower cervical transection. This activity occurs up to 5 days following trauma, an effect which correlates with the induction of ventilation failure and respiratory dysfunction in human patients with SCI. The clinical implications of this finding are provocative. 60% of patients undergo some degree of respiratory distress following acute C5–8 injuries. Using this pathway, it may be possible to modestly stimulate or activate sympathetic activity to further aid intercostal muscle activity and respiratory function following acute SCI. This thus represents a novel target for the treatment of respiratory dysfunction following spinal trauma. [Figure: see text]

An Experimental Study on the Treatment of Spinal Cord Injury in Rats by Tissue Engineering Method that Uses ADSCs Modified by BDNF and NT-3 Double Genes Combing the use of SFCS

Introduction Adipose-derived stem cells (ADSCs) possess the potential of multi-differentiation which could differentiate into neuronal cells and Schwann cells under certain conditions. If we inoculate the ADSCs modified by Brain derived neurophic factor(BDNF) and Neurotrophin-3(NT-3)double genes on the silk fibroin/chitosan (SFCS), and transplant it into 2 mm pre-made spinal cord transection animal model, we can take advantage of the characteristic of ADSCs which could express BDNF and NT-3 stably after being double gene modified and the advantage of tissue engineering, we look forward to providing a new treatment method for spinal cord injury (SCI), which thereby could reduce SCI morbidity and mortality rate, so as to build up a solid theoretical foundation for the clinical treatment of SCI. Material and Methods According to the preliminary design, animal experiment is divided into seven groups: Group A: SFCS/ADSCs/Lenti-BDNF-GFP-NT-3-RFP, namely, BDNF and NT-3 double genes co-transfect ADSCs combining SFCS group; Group B: SFCS/ADSCs/Lenti-BDNF-GFP, namely, BDNF single gene transfect ADSCs combining SFCS group; Group C: SFCS/ADSCs/ Lenti-NT-3-RFP, namely, NT-3 single gene transfect ADSCs combining SFCS group; Group D: SFCS/ADSCs/Lenti-eGFP, namely, empty vector transfect ADSCs combining SFCS group; Group E:SFCS, namely, single SFCS group; Group F:only cut off spinal cord and without treatment; Group G: normal control group, just open the vertebral plate without any treatment. Group A, B, C, D and E transplant the scaffold into 2 mm spinal cord transection defect rat model. Group F cuts off spinal cord and makes 2 mm defect, Group G is normal group. Do a BBB scoring at 1 w, 4 w, 8 w and 12 w after surgery to analyze functional recovery, execute the rats 12 w later, take out the scaffolds, test them by HE staining, immunehistochemical staining (NSE, GAP-43, Caspase-3, GFAP), LFB staining, RT-PCR and Western blot, the purpose of which is to observe the effect of tissue engineering on the recovery of SCI. Results Group A (BDNF and NT-3 double genes modified ADSCs combining the use of SFCS group) has a better repair effect on rats spinal cord transection injury treatment, which reveals higher BBB scores, increased GAP-43 expression, more positive NSE cells, decreased expression of GFAP and Caspase-3. At the same time denser regenerating nerve fiber could move through the scaffold, and the most important thing is the repair effect of Group A is better than single gene modified Group B and Group C, which is better than Group D (empty vector transfect ADSCs combining SFCS group), which is better than Group E (single use SFCS), which is better than Group F (just cut off spinal cord and without treatment). Conclusion Under the guidance of tissue engineering method, ADSCs modified by BDNF and NT-3 double genes combining the use of SFCS can significantly reduce the inflammatory response after injury, inhibit scar hyperplasia and cell apoptosis and promote nerve fibers regeneration and the differentiation of ADSCs into neurons in vivo, so as to improve the repair effect of rat spinal cord transection injuries, which provides a new method for the treatment of SCI.

Erratum to: Lentiviral-Mediated Netrin-1 Overexpression Improves Motor and Sensory Functions in SCT Rats Associated with SYP and GAP-43 Expressions.

Spinal cord injury (SCI), as a major cause of disability, usually causes serious loss of motor and sensory functions. As a bifunctional axonal guidance cue, netrin-1 can attract axons via the deleted in colorectal cancer (DCC) receptors and repelling others via Unc5 receptors, but its exact role in the recovery of motor and sensory function has not well been studied, and the mechanisms remains elusive. The aim of this experiment is to determine whether lentiviral (LV)-mediated overexpression of netrin-1 or RNA interference (RNAi) can regulate the functional recovery in rats subjected to spinal cord transection (SCT). Firstly, two lentiviral vectors including Lv-exNtn-1 (netrin-1 open reading frame (ORF)) and Lv-shNtn-1 (netrin-1 sh) were constructed and injected into spinal cords rostral and caudal to the transected lesion site. Overexpressing netrin-1 enhanced significantly locomotor function, and reduced thermal and mechanical stimuli in vivo, compared with the control, while silencing netrin-1 did not significantly change the situation. Western blot and immunostaining analysis confirmed that netrin-1 ORF treatment not only effectively increased the expression level of netrin-1, also up-regulated the level of synaptophysin (SYP) in spinal cord rostral to the lesion, but also enhanced growth-associated protein-43 (GAP-43) expression in spinal cord caudal to the lesion site. Comparatively, knockdown of netrin-1 did not give rise to positive findings in our experimental condition. These findings therefore pointed that Lv-mediated netrin-1 overexpression could promote motor and sensory functional recoveries following SCT, and the underlying mechanisms were associated with SYP and GAP-43 expressions. The present study therefore provided a novel strategy for the treatment of SCI and explained the possible mechanisms for the functional improvement.

654 Is an early anticholinergic treatment able to prevent detrusor overactivity after spinal cord transection in rats?

654 Is an early anticholinergic treatment able to prevent detrusor overactivity after spinal cord transection in rats?

MiR-434-3p and DNA hypomethylation co-regulate eIF5A1 to increase AChRs and to improve plasticity in SCT rat skeletal muscle.

Acetylcholine receptors (AChRs) serve as connections between motor neurons and skeletal muscle and are essential for recovery from spinal cord transection (SCT). Recently, microRNAs have emerged as important potential biotherapeutics for several diseases; however, whether miRNAs operate in the modulation of AChRs remains unknown. We found increased AChRs numbers and function scores in rats with SCT; these increases were reduced following the injection of a eukaryotic translation initiation factor 5A1 (eIF5A1) shRNA lentivirus into the hindlimb muscle. Then, high-throughput screening for microRNAs targeting eIF5A1 was performed, and miR-434-3p was found to be robustly depleted in SCT rat skeletal muscle. Furthermore, a highly conserved miR-434-3p binding site was identified within the mRNA encoding eIF5A1 through bioinformatics analysis and dual-luciferase assay. Overexpression or knockdown of miR-434-3p in vivo demonstrated it was a negative post-transcriptional regulator of eIF5A1 expression and influenced AChRs expression. The microarray-enriched Gene Ontology (GO) terms regulated by miR-434-3p were muscle development terms. Using a lentivirus, one functional gene (map2k6) was confirmed to have a similar function to that of miR-434-3p in GO terms. Finally, HRM and MeDIP-PCR analyses revealed that DNA demethylation also up-regulated eIF5A1 after SCT. Consequently, miR-434-3p/eIF5A1 in muscle is a promising potential biotherapy for SCI repair.

Biofunctionalized PEDOT-coated microfibers for the treatment of spinal cord injury

Poly(3, 4-ethylenedioxythiophene)-coated carbon microfibers (PEDOT-MFs) hold promise for developing advanced neuroprostheses and neural repair devices. We investigated the chronic cellular responses to PEDOT-MFs implanted into the uninjured and the transected rat spinal cord, and compared the effects of polymer surface biofunctionalization with covalently attached polylysine (PLL) or a multimolecular complex of PLL, heparin, basic fibroblast growth factor (bFGF), and fibronectin. An alginate gel was used to facilitate microfiber implantation and reduce connective tissue scarring after spinal cord injury (SCI). PLL/heparin/bFGF/fibronectin-functionalized PEDOT-MFs showed excellent integration within the uninjured and injured spinal cord, frequently establishing contact with neuronal somas, axons, dendrites and glial cells, accompanied by very little or absent scarring response. On the contrary, non-functionalized and PLL-functionalized microfibers provoked inflammation and fibrosis with loss of neural elements in the surrounding tissue. Within the lesion, the PEDOT-MFs by themselves facilitated longitudinal alignment of migratory cells and growing axons, and their modification with PLL/heparin/bFGF/fibronectin promoted tissue healing, enhancing blood vessel formation and axonal regeneration without increasing inflammation. These results support the incorporation of biofunctionalized electroconducting microfibers in neuro–electronic interfaces and lesion-bridging systems for the treatment of SCI.

Lentiviral-Mediated Netrin-1 Overexpression Improves Motor and Sensory Functions in SCT Rats Associated with SYP and GAP-43 Expressions.

Spinal cord injury (SCI), as a major cause of disability, usually causes serious loss of motor and sensory functions. As a bifunctional axonal guidance cue, netrin-1 can attract axons via the deleted in colorectal cancer (DCC) receptors and repelling others via Unc5 receptors, but its exact role in the recovery of motor and sensory function has not well been studied, and the mechanisms remains elusive. The aim of this experiment is to determine whether lentiviral (LV)-mediated overexpression of netrin-1 or RNA interference (RNAi) can regulate the functional recovery in rats subjected to spinal cord transection (SCT). Firstly, two lentiviral vectors including Lv-exNtn-1 (netrin-1 open reading frame (ORF)) and Lv-shNtn-1 (netrin-1 sh) were constructed and injected into spinal cords rostral and caudal to the transected lesion site. Overexpressing netrin-1 enhanced significantly locomotor function, and reduced thermal and mechanical stimuli in vivo, compared with the control, while silencing netrin-1 did not significantly change the situation. Western blot and immunostaining analysis confirmed that netrin-1 ORF treatment not only effectively increased the expression level of netrin-1, also up-regulated the level of synaptophysin (SYP) in spinal cord rostral to the lesion, but also enhanced growth-associated protein-43 (GAP-43) expression in spinal cord caudal to the lesion site. Comparatively, knockdown of netrin-1 did not give rise to positive findings in our experimental condition. These findings therefore pointed that Lv-mediated netrin-1 overexpression could promote motor and sensory functional recoveries following SCT, and the underlying mechanisms were associated with SYP and GAP-43 expressions. The present study therefore provided a novel strategy for the treatment of SCI and explained the possible mechanisms for the functional improvement.

Knockdown of α-synuclein in cerebral cortex improves neural behavior associated with apoptotic inhibition and neurotrophin expression in spinal cord transected rats.

Spinal cord injury (SCI) often causes severe functional impairment with poor recovery. The treatment, however, is far from satisfaction, and the mechanisms remain unclear. By using proteomics and western blot, we found spinal cord transection (SCT) resulted in a significant down-regulation of α-synuclein (SNCA) in the motor cortex of SCT rats at 3days post-operation. In order to detect the role of SNCA, we used SNCA-ORF/shRNA lentivirus to upregulate or knockdown SNCA expression. In vivo, SNCA-shRNA lentivirus injection into the cerebral cortex motor area not only inhibited SNCA expression, but also significantly enhanced neurons' survival, and attenuated neuronal apoptosis, as well as promoted motor and sensory function recovery in hind limbs. While, overexpression SNCA exhibited the opposite effects. In vitro, cortical neurons transfected with SNCA-shRNA lentivirus gave rise to an optimal neuronal survival and neurite outgrowth, while it was accompanied by reverse efficiency in SNCA-ORF group. In molecular level, SNCA silence induced the upregulation of Bcl-2 and the downregulation of Bax, and the expression of NGF, BDNF and NT3 was substantially upregulated in cortical neurons. Together, endogenous SNCA play a crucial role in motor and sensory function regulation, in which, the underlying mechanism may be linked to the regulation of apoptosis associated with apoptotic gene (Bax, Bcl2) and neurotrophic factors expression (NGF, BDNF and NT3). These finds provide novel insights to understand the role of SNCA in cerebral cortex after SCT, and it may be as a novel treatment target for SCI repair in future clinic trials.

A 176-Channel 0.5cm3 0.7g Wireless Implant for Motor Function Recovery after Spinal Cord Injury.

Epidural spinal stimulation has shown effectiveness in recovering the motor function of spinal cord transected rats by modulating neural networks in lumbosacral spinal segments [1, 2]. The state-of-the-art neuromodulation implant [3] reports a 4-channel stimulator with wireless data and power links for small animal experiments, yet weighs 6g and has a volume of 3cm3. It is preferable that the implant package has a comparable size to its bioelectronics and a high-density stimulator to support stimulation with high spatial resolution. Furthermore, the epidural electrode should be soft and flexible because a mechanical mismatch exists at the tissue-electrode interface [1]. Unlike other implant/SoCs that stimulate with pre-loaded patterns [4–5], the implant for motor function recovery should be capable of adaptively adjusting its stimulation patterns at run time in response to the subject's varying physiological states [2]. Measuring the electrode-tissue impedance is also critical to ensure safe stimulation. Deriving the equivalent circuit model of the electrode-tissue interface determines the safe stimulation boundary (i.e. pulse width and intensity) to ensure the electrode overpotential is within the water window [6]. However, an SoC implementation of this function has not been reported.

Effect of FGF-2 and sciatic nerve grafting on ChAT expression in dorsal root ganglia neurons of spinal cord transected rats

Neurotrophic factors and peripheral nerves are known to be good substrates for bridging CNS trauma. The involvement of fibroblast growth factor-2 (FGF-2) activation in the dorsal root ganglion (DRG) was examined following spinal cord injury in the rat. We evaluated whether FGF-2 increases the ability of a sciatic nerve graft to enhance neuronal plasticity, in a gap promoted by complete transection of the spinal cord. The rats were subjected to a 4mm-long gap at low thoracic level and were repaired with saline (Saline or control group, n=10), or fragment of the sciatic nerve (Nerve group, n=10), or fragment of the sciatic nerve to which FGF-2 (Nerve+FGF-2 group, n=10) had been added immediately after lesion. The effects of the FGF-2 and fragment of the sciatic nerve grafts on neuronal plasticity were investigated using choline acetyl transferase (ChAT)-immunoreactivity of neurons in the dorsal root ganglion after 8 weeks. Preservation of the area and diameter of neuronal cell bodies in dorsal root ganglion (DRG) was seen in animals treated with the sciatic nerve, an effect enhanced by the addition of FGF-2. Thus, the addition of exogenous FGF-2 to a sciatic nerve fragment grafted in a gap of the rat spinal cord submitted to complete transection was able to improve neuroprotection in the DRG. The results emphasized that the manipulation of the microenvironment in the wound might amplify the regenerative capacity of peripheral neurons.

Donor mesenchymal stem cell-derived neural-like cells transdifferentiate into myelin-forming cells and promote axon regeneration in rat spinal cord transection.

IntroductionSevere spinal cord injury often causes temporary or permanent damages in strength, sensation, or autonomic functions below the site of the injury. So far, there is still no effective treatment for spinal cord injury. Mesenchymal stem cells (MSCs) have been used to repair injured spinal cord as an effective strategy. However, the low neural differentiation frequency of MSCs has limited its application. The present study attempted to explore whether the grafted MSC-derived neural-like cells in a gelatin sponge (GS) scaffold could maintain neural features or transdifferentiate into myelin-forming cells in the transected spinal cord.MethodsWe constructed an engineered tissue by co-seeding of MSCs with genetically enhanced expression of neurotrophin-3 (NT-3) and its high-affinity receptor tropomyosin receptor kinase C (TrkC) separately into a three-dimensional GS scaffold to promote the MSCs differentiating into neural-like cells and transplanted it into the gap of a completely transected rat spinal cord. The rats received extensive post-operation care, including cyclosporin A administrated once daily for 2 months.ResultsMSCs modified genetically could differentiate into neural-like cells in the MN + MT (NT-3-MSCs + TrKC-MSCs) group 14 days after culture in the GS scaffold. However, after the MSC-derived neural-like cells were transplanted into the injury site of spinal cord, some of them appeared to lose the neural phenotypes and instead transdifferentiated into myelin-forming cells at 8 weeks. In the latter, the MSC-derived myelin-forming cells established myelin sheaths associated with the host regenerating axons. And the injured host neurons were rescued, and axon regeneration was induced by grafted MSCs modified genetically. In addition, the cortical motor evoked potential and hindlimb locomotion were significantly ameliorated in the rat spinal cord transected in the MN + MT group compared with the GS and MSC groups.ConclusionGrafted MSC-derived neural-like cells in the GS scaffold can transdifferentiate into myelin-forming cells in the completely transected rat spinal cord.Electronic supplementary materialThe online version of this article (doi:10.1186/s13287-015-0100-7) contains supplementary material, which is available to authorized users.

Complete rat spinal cord transection as a faithful model of spinal cord injury for translational cell transplantation.

Spinal cord injury (SCI) results in neural loss and consequently motor and sensory impairment below the injury. There are currently no effective therapies for the treatment of traumatic SCI in humans. Various animal models have been developed to mimic human SCI. Widely used animal models of SCI are complete or partial transection or experimental contusion and compression, with both bearing controversy as to which one more appropriately reproduces the human SCI functional consequences. Here we present in details the widely used procedure of complete spinal cord transection as a faithful animal model to investigate neural and functional repair of the damaged tissue by exogenous human transplanted cells. This injury model offers the advantage of complete damage to a spinal cord at a defined place and time, is relatively simple to standardize and is highly reproducible.

Tissue-engineered regeneration of completely transected spinal cord using induced neural stem cells and gelatin-electrospun poly (lactide-co-glycolide)/polyethylene glycol scaffolds.

Tissue engineering has brought new possibilities for the treatment of spinal cord injury. Two important components for tissue engineering of the spinal cord include a suitable cell source and scaffold. In our study, we investigated induced mouse embryonic fibroblasts (MEFs) directly reprogrammed into neural stem cells (iNSCs), as a cell source. Three-dimensional (3D) electrospun poly (lactide-co-glycolide)/polyethylene glycol (PLGA-PEG) nanofiber scaffolds were used for iNSCs adhesion and growth. Cell growth, survival and proliferation on the scaffolds were investigated. Scanning electron microcopy (SEM) and nuclei staining were used to assess cell growth on the scaffolds. Scaffolds with iNSCs were then transplanted into transected rat spinal cords. Two or 8 weeks following transplantation, immunofluorescence was performed to determine iNSC survival and differentiation within the scaffolds. Functional recovery was assessed using the Basso, Beattie, Bresnahan (BBB) Scale. Results indicated that iNSCs showed similar morphological features with wild-type neural stem cells (wt-NSCs), and expressed a variety of neural stem cell marker genes. Furthermore, iNSCs were shown to survive, with the ability to self-renew and undergo neural differentiation into neurons and glial cells within the 3D scaffolds in vivo. The iNSC-seeded scaffolds restored the continuity of the spinal cord and reduced cavity formation. Additionally, iNSC-seeded scaffolds contributed to functional recovery of the spinal cord. Therefore, PLGA-PEG scaffolds seeded with iNSCs may serve as promising supporting transplants for repairing spinal cord injury (SCI).