Ion channel blockers and spinal cord injury

Progression of mesenchymal stem cell regulation on imbalanced microenvironment after spinal cord injury

Spinal cord injury (SCI) results in significant neural damage and inhibition of axonal regeneration due to an imbalanced microenvironment. Extensive evidence supports the efficacy of mesenchymal stem cell (MSC) transplantation as a therapeutic approach for SCI. This review aims to present an overview of MSC regulation on the imbalanced microenvironment following SCI, specifically focusing on inflammation, neurotrophy and axonal regeneration. The application, limitations and future prospects of MSC transplantation are discussed as well. Generally, a comprehensive perspective is provided for the clinical translation of MSC transplantation for SCI.

Mapping the landscape: A bibliometric perspective on autophagy in spinal cord injury

BACKGROUND

Spinal cord injury (SCI) is a severe condition that often leads to persistent damage of nerve cells and motor dysfunction. Autophagy is an intracellular system that regulates the recycling and degradation of proteins and lipids, primarily through lysosomal-dependent organelle degradation. Numerous publications have highlighted the involvement of autophagy in the secondary injury of SCI. Therefore, gaining a comprehensive understanding of autophagy research is crucial for designing effective therapies for SCI.

METHODS

Dates were obtained from Web of Science, including articles and article reviews published from its inception to October 2023. VOSviewer, Citespace, and SCImago were used to visualized analysis. Bibliometric analysis was conducted using the Web of Science data, focusing on various categories such as publications, authors, journals, countries, organizations, and keywords. This analysis was aimed to summarize the knowledge map of autophagy and SCI.

RESULTS

From 2009 to 2023, the number of annual publications in this field exhibited wave-like growth, with the highest number of publications recorded in 2020 (44 publications). Our analysis identified Mei Xifan as the most prolific author, while Kanno H emerged as the most influential author based on co-citations. Neuroscience Letters was found to have published the largest number of papers in this field. China was the most productive country, contributing 232 publications, and Wenzhou Medical University was the most active organization, publishing 39 papers.

CONCLUSION

We demonstrated a comprehensive overview of the relationship between autophagy and SCI utilizing bibliometric tools. This article could help to enhance the understanding of the field about autophagy and SCI, foster collaboration among researchers and organizations, and identify potential therapeutic targets for treatment.

Tail and Spinal Cord Regeneration in Urodelean Amphibians

Urodelean amphibians can regenerate the tail and the spinal cord (SC) and maintain this ability throughout their life. This clearly distinguishes these animals from mammals. The phenomenon of tail and SC regeneration is based on the capability of cells involved in regeneration to dedifferentiate, enter the cell cycle, and change their (or return to the pre-existing) phenotype during de novo organ formation. The second critical aspect of the successful tail and SC regeneration is the mutual molecular regulation by tissues, of which the SC and the apical wound epidermis are the leaders. Molecular regulatory systems include signaling pathways components, inflammatory factors, ECM molecules, ROS, hormones, neurotransmitters, HSPs, transcriptional and epigenetic factors, etc. The control, carried out by regulatory networks on the feedback principle, recruits the mechanisms used in embryogenesis and accompanies all stages of organ regeneration, from the moment of damage to the completion of morphogenesis and patterning of all its structures. The late regeneration stages and the effects of external factors on them have been poorly studied. A new model for addressing this issue is herein proposed. The data summarized in the review contribute to understanding a wide range of fundamentally important issues in the regenerative biology of tissues and organs in vertebrates including humans.

Omega-conotoxin MVIIA reduces neuropathic pain after spinal cord injury by inhibiting N-type voltage-dependent calcium channels on spinal dorsal horn

Spinal cord injury (SCI) leads to the development of neuropathic pain. Although a multitude of pathological processes contribute to SCI-induced pain, excessive intracellular calcium accumulation and voltage-gated calcium-channel upregulation play critical roles in SCI-induced pain. However, the role of calcium-channel blockers in SCI-induced pain is unknown. Omega-conotoxin MVIIA (MVIIA) is a calcium-channel blocker that selectively inhibits N-type voltage-dependent calcium channels and demonstrates neuroprotective effects. Therefore, we investigated spinal analgesic actions and cellular mechanisms underlying the analgesic effects of MVIIA in SCI. We used SCI-induced pain model rats and conducted behavioral tests, immunohistochemical analyses, and electrophysiological experiments (in vitro whole-cell patch-clamp recording and in vivo extracellular recording). A behavior study suggested intrathecal MVIIA administration in the acute phase after SCI induced analgesia for mechanical allodynia. Immunohistochemical experiments and in vivo extracellular recordings suggested that MVIIA induces analgesia in SCI-induced pain by directly inhibiting neuronal activity in the superficial spinal dorsal horn. In vitro whole-cell patch-clamp recording showed that MVIIA inhibits presynaptic N-type voltage-dependent calcium channels expressed on primary afferent Aδ-and C-fiber terminals and suppresses the presynaptic glutamate release from substantia gelatinosa in the spinal dorsal horn. In conclusion, MVIIA administration in the acute phase after SCI may induce analgesia in SCI-induced pain by inhibiting N-type voltage-dependent calcium channels on Aδ-and C-fiber terminals in the spinal dorsal horn, resulting in decreased neuronal excitability enhanced by SCI-induced pain.

The impact of time from injury to surgery on the risk of neuropathic pain after traumatic spinal cord injury

Traumatic spinal cord injury (SCI) is a devastating neurological disorder often accompanied by neuropathic pain (NeP), significantly affecting patients' quality of life. This retrospective study aimed to investigate the impact of the time from injury to surgery on the development of NeP following traumatic SCI. Medical records of patients with traumatic SCI who underwent surgical intervention between January 2017 and January 2021 at two specialized centers were reviewed. Variables associated with NeP including demographics, injury profiles, medical history, surgical details, and pain assessments were investigated. Independent risk factors related to NeP were identified using multivariate logistic regression analysis. A total of 320 patients met the inclusion criteria, with 245 (76.6%) being male and a mean age of 56.5 ± 13.2 years. NeP was identified in 48.4% of patients (155 of 320). The multivariate analysis identifies age at injury, Injury Severity Score, and the neurological level of injury as independent risk factors for the development of NeP in both AIS A and AIS B, C, and D subgroups. Additionally, a significant association between the time from injury to surgery and NeP was observed in AIS B, C, and D patients, while no such association was found in AIS A patients. This study highlights the benefits of early and ultra-early surgical intervention in preventing NeP in patients with incomplete traumatic SCI (AIS B, C, and D), underscoring the importance of optimizing surgical timing to improve patient outcomes. Prospective studies are warranted to establish evidence-based surgical guidelines for managing traumatic SCI and preventing NeP effectively.

Modulating neuroinflammation through molecular, cellular and biomaterial-based approaches to treat spinal cord injury

The neuroinflammatory response that is elicited after spinal cord injury contributes to both tissue damage and reparative processes. The complex and dynamic cellular and molecular changes within the spinal cord microenvironment result in a functional imbalance of immune cells and their modulatory factors. To facilitate wound healing and repair, it is necessary to manipulate the immunological pathways during neuroinflammation to achieve successful therapeutic interventions. In this review, recent advancements and fresh perspectives on the consequences of neuroinflammation after SCI and modulation of the inflammatory responses through the use of molecular-, cellular-, and biomaterial-based therapies to promote tissue regeneration and functional recovery will be discussed.

Electrical stimulation for the treatment of spinal cord injuries: A review of the cellular and molecular mechanisms that drive functional improvements

Spinal cord injury (SCI) is a devastating condition that causes severe loss of motor, sensory and autonomic functions. Additionally, many individuals experience chronic neuropathic pain that is often refractory to interventions. While treatment options to improve outcomes for individuals with SCI remain limited, significant research efforts in the field of electrical stimulation have made promising advancements. Epidural electrical stimulation, peripheral nerve stimulation, and functional electrical stimulation have shown promising improvements for individuals with SCI, ranging from complete weight-bearing locomotion to the recovery of sexual function. Despite this, there is a paucity of mechanistic understanding, limiting our ability to optimize stimulation devices and parameters, or utilize combinatorial treatments to maximize efficacy. This review provides a background into SCI pathophysiology and electrical stimulation methods, before exploring cellular and molecular mechanisms suggested in the literature. We highlight several key mechanisms that contribute to functional improvements from electrical stimulation, identify gaps in current knowledge and highlight potential research avenues for future studies.

Neurotoxins Acting at Synaptic Sites: A Brief Review on Mechanisms and Clinical Applications

Neurotoxins generally inhibit or promote the release of neurotransmitters or bind to receptors that are located in the pre- or post-synaptic membranes, thereby affecting physiological functions of synapses and affecting biological processes. With more and more research on the toxins of various origins, many neurotoxins are now widely used in clinical treatment and have demonstrated good therapeutic outcomes. This review summarizes the structural properties and potential pharmacological effects of neurotoxins acting on different components of the synapse, as well as their important clinical applications, thus could be a useful reference for researchers and clinicians in the study of neurotoxins.

Molecular Mechanisms in the Vascular and Nervous Systems following Traumatic Spinal Cord Injury

Traumatic spinal cord injury (SCI) induces various complex pathological processes that cause physical impairment and psychological devastation. The two phases of SCI are primary mechanical damage (the immediate result of trauma) and secondary injury (which occurs over a period of minutes to weeks). After the mechanical impact, vascular disruption, inflammation, demyelination, neuronal cell death, and glial scar formation occur during the acute phase. This sequence of events impedes nerve regeneration. In the nervous system, various extracellular secretory factors such as neurotrophic factors, growth factors, and cytokines are involved in these events. In the vascular system, the blood-spinal cord barrier (BSCB) is damaged, allowing immune cells to infiltrate the parenchyma. Later, endogenous angiogenesis is promoted during the subacute phase. In this review, we describe the roles of secretory factors in the nervous and vascular systems following traumatic SCI, and discuss the outcomes of their therapeutic application in traumatic SCI.

Long-term administration of bumetanide improve functional recovery after spinal cord injury in rats

Ion disturbances are among the most remarkable deficits in spinal cord injury (SCI). GABA is an integral part of neural interaction. Action of the GABAA receptor depends on the amount of intracellular chloride. Homeostasis of chloride is controlled by two co-transporters, NKCC1 and KCC2. Previous studies revealed that NKCC1 are disturbed in SCI. In this study, NKCC1 is highly expressed in the epicenter of the lesioned spinal cord at 3 hours after induction of the lesion and reached the peak around 6 hours after SCI. Bumetanide (2 and 4 mg/day), as a specific NKCC1 inhibitor, was used at 3 hours post SCI for 28 days. The functional recovery outcomes were measured by the Basso-Beattie-Bresnahan (BBB) locomotor rating scale, ladder walking test, and hot plate test. The rats that received bumetanide 4 mg/day exhibited improved recovery of locomotor function, reduction of NKCC1 gene expression, and upregulation of GAP protein levels 28 days post SCI. Histological tissue evaluations confirmed bumetanide's neuroprotective and regenerative effects. This study provides novel evidence for the benefits of bumetanide in early administration after SCI.

Is Graphene Shortening the Path toward Spinal Cord Regeneration?

Along with the development of the next generation of biomedical platforms, the inclusion of graphene-based materials (GBMs) into therapeutics for spinal cord injury (SCI) has potential to nourish topmost neuroprotective and neuroregenerative strategies for enhancing neural structural and physiological recovery. In the context of SCI, contemplated as one of the most convoluted challenges of modern medicine, this review first provides an overview of its characteristics and pathophysiological features. Then, the most relevant ongoing clinical trials targeting SCI, including pharmaceutical, robotics/neuromodulation, and scaffolding approaches, are introduced and discussed in sequence with the most important insights brought by GBMs into each particular topic. The current role of these nanomaterials on restoring the spinal cord microenvironment after injury is critically contextualized, while proposing future concepts and desirable outputs for graphene-based technologies aiming to reach clinical significance for SCI.

Neuroprotective effect of CTK 01512-2 recombinant toxin at the spinal cord in a model of Huntington's disease

NEW FINDINGS

What is the central question of this study? We investigated the action of intrathecal administration of a novel toxin (CTK01512-2) in a mouse model for Huntington´s disease (HD). We asked if spinal cord neurons can represent a therapeutic target, as the spinal cord seems to be involved in HD motor-symptoms. Pharmacological approaches focusing on the spinal cord and skeletal muscles might represent a more feasible strategy. What is the main finding and its importance? We provided evidence of a novel, local, neuroprotector effect of CTK01512-2, paving a path for the development of approaches to treat HD-motor symptoms beyond the brain.

ABSTRACT

Phα1β is a neurotoxin from the venom of the Phoneutria nigriventer spider, available as CTK01512-2, a recombinant peptide. Due to its antinociceptive and analgesic properties, CTK01512-2 has been described to alleviate neuroinflammatory responses. Despite the diverse CTK01512-2 actions on the nervous system, little is known regarding its neuroprotective effect, especially in neurodegenerative conditions such as Huntington's disease (HD), a genetic movement disorder without cure. Here, we investigated whether CTK01512-2 has a neuroprotector effect in a mouse model of HD. We hypothesized that spinal cord neurons might represent a therapeutic target, as the spinal cord seems to be involved in the motor-symptoms of HD mice (BACHD). Then, we treated BACHD mice with CTK01512-2 by intrathecal injection, and performed in vivo motor behavior and morphological analyses in the central nervous system (brain and spinal cord) and muscles. Our data showed that intrathecal injection of CTK01512-2 significantly improves motor-performance in the Open-field task. CTK01512-2 protects neurons in the spinal cord (but not in the brain) from death, suggesting a local effect. CTK01512-2 exerts its neuroprotective effect by inhibiting BACHD-neuronal apoptosis, as revealed by a reduction in caspase-3 in the spinal cord. CTK01512-2 was also able to revert BACHD muscle atrophy. In conclusion, our data provide a novel role for CTK01512-2 acting directly in the spinal cord, ameliorating morphofunctional aspects of spinal cord neurons, and muscles, and improving BACHD mice performance in motor-behavioral tests. Since HD shares similar symptoms to many neurodegenerative conditions, the findings presented herein may also be applicable to other disorders. This article is protected by copyright. All rights reserved.

Neurogenesis as a Tool for Spinal Cord Injury

Spinal cord injury is a devastating medical condition with no effective treatment. One approach to SCI treatment may be provided by stem cells (SCs). Studies have mainly focused on the transplantation of exogenous SCs, but the induction of endogenous SCs has also been considered as an alternative. While the differentiation potential of neural stem cells in the brain neurogenic regions has been known for decades, there are ongoing debates regarding the multipotent differentiation potential of the ependymal cells of the central canal in the spinal cord (SCECs). Following spinal cord insult, SCECs start to proliferate and differentiate mostly into astrocytes and partly into oligodendrocytes, but not into neurons. However, there are several approaches concerning how to increase neurogenesis in the injured spinal cord, which are discussed in this review. The potential treatment approaches include drug administration, the reduction of neuroinflammation, neuromodulation with physical factors and in vivo reprogramming.

Exploring Molecular Approaches in Amyotrophic Lateral Sclerosis: Drug Targets from Clinical and Pre-Clinical Findings

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease (MND) characterized by the death of upper and lower motor neurons (corticospinal tract) in the motor cortex, basal ganglia, brain stem, and spinal cord. The patient experiences the sign and symptoms between 55 to 75 years of age, which include impaired motor movement, difficulty in speaking and swallowing, grip loss, muscle atrophy, spasticity, and sometimes associated with memory and cognitive impairments. Median survival is 3 to 5 years after diagnosis and 5 to 10% of the patients live for more than 10 years. The limited intervention of pharmacologically active compounds, that are used clinically, is majorly associated with the narrow therapeutic index. Pre-clinically established experimental models, where neurotoxin methyl mercury mimics the ALS like behavioural and neurochemical alterations in rodents associated with neuronal mitochondrial dysfunctions and downregulation of adenyl cyclase mediated cAMP/CREB, is the main pathological hallmark for the progression of ALS in central as well in the peripheral nervous system. Despite the considerable investigation into neuroprotection, it still constrains treatment choices to strong care and organization of ALS complications. Therefore, this current review specially targeted the investigation of clinical and pre-clinical features available for ALS to understand the pathogenic mechanisms and to explore the pharmacological interventions associated with the up-regulation of intracellular adenyl cyclase/cAMP/ CREB and activation of mitochondrial-ETC coenzyme-Q10 as a future drug target in the amelioration of ALS mediated motor neuronal dysfunctions.

Protein Degradome of Spinal Cord Injury: Biomarkers and Potential Therapeutic Targets

Degradomics is a proteomics sub-discipline whose goal is to identify and characterize protease-substrate repertoires. With the aim of deciphering and characterizing key signature breakdown products, degradomics emerged to define encryptic biomarker neoproteins specific to certain disease processes. Remarkable improvements in structural and analytical experimental methodologies as evident in research investigating cellular behavior in neuroscience and cancer have allowed the identification of specific degradomes, increasing our knowledge about proteases and their regulators and substrates along with their implications in health and disease. A physiologic balance between protein synthesis and degradation is sought with the activation of proteolytic enzymes such as calpains, caspases, cathepsins, and matrix metalloproteinases. Proteolysis is essential for development, growth, and regeneration; however, inappropriate and uncontrolled activation of the proteolytic system renders the diseased tissue susceptible to further neurotoxic processes. In this article, we aim to review the protease-substrate repertoires as well as emerging therapeutic interventions in spinal cord injury at the degradomic level. Several protease substrates and their breakdown products, essential for the neuronal structural integrity and functional capacity, have been characterized in neurotrauma including cytoskeletal proteins, neuronal extracellular matrix glycoproteins, cell junction proteins, and ion channels. Therefore, targeting exaggerated protease activity provides a potentially effective therapeutic approach in the management of protease-mediated neurotoxicity in reducing the extent of damage secondary to spinal cord injury.

MAP‑1B, PACS‑2 and AHCYL1 are regulated by miR‑34A/B/C and miR‑449 in neuroplasticity following traumatic spinal cord injury in rats: Preliminary explorative results from microarray data

Spinal cord injury (SCI) is a specific type of damage to the central nervous system causing temporary or permanent changes in its function. The present aimed to identify the genetic changes in neuroplasticity following SCI in rats. The GSE52763 microarray dataset, which included 15 samples [3 sham (1 week), 4 injury only (1 week), 4 injury only (3 weeks), 4 injury + treadmill (3 weeks)] was downloaded from the Gene Expression Omnibus database. An empirical Bayes linear regression model in limma package was used to identify the differentially expressed genes (DEGs) in injury vs. sham and treadmill vs. non‑treadmill comparison groups. Subsequently, time series and enrichment analyses were performed using pheatmap and clusterProfile packages, respectively. Additionally, protein‑protein interaction (PPI) and transcription factor (TF)‑microRNA (miRNA)‑target regulatory networks were constructed using Cytoscape software. In total, 159 and 105 DEGs were identified in injury vs. sham groups and treadmill vs. non‑treadmill groups, respectively. There were 40 genes in cluster 1 that presented increased expression levels in the injury (1 week/3 weeks) groups compared with the sham group, and decreased expression levels in the injury + treadmill group compared with the injury only groups; conversely, 52 genes in cluster 2 exhibited decreased expression levels in the injury (1 week/3 weeks) groups compared with the sham group, and increased expression levels in the injury + treadmill group compared with the injury only groups. Enrichment analysis indicated that clusters 1 and 2 were associated with immune response and signal transduction, respectively. Furthermore, microtubule associated protein 1B, phosphofurin acidic cluster sorting protein 2 and adenosylhomocysteinase‑like 1 exhibited the highest degrees in the regulatory network, and were regulated by miRNAs including miR‑34A, miR‑34B, miR‑34C and miR‑449. These miRNAs and their target genes may serve important roles in neuroplasticity following traumatic SCI in rats. Nevertheless, additional in‑depth studies are required to confirm these data.

Zhenbao Pill reduces Treg cell proportion in acute spinal cord injury rats by regulating TUG1/miR-214/HSP27 axis

Background: Acute spinal cord injury (SCI) is one of the weakest pathologies that seriously affect the quality of life of patients. Objective: To study the mechanism of how Zhenbao Pill reduces Treg cell proportion and improves acute SCI. Methods: A rat SCI model was established. Flow cytometry analysis was performed to determine the Treg cell proportion. RNA immunoprecipitation (RIP) and RNA pull-down were applied in confirming taurine up-regulated gene 1 (TUG1) and miR-214 binding. Intrathecal injection of TUG1 siRNA was also conducted to determine the effect of TUG1 in vivoResults: Zhenbao Pill promoted the expression of TUG1 and heat shock protein 27 (HSP27) protein, and reduced the expression of miR-214 and forkhead box protein p3 (Foxp3) as well as Treg cell proportion in a concentration-dependent manner in SCI rats or in vitro cultured CD4+ T cells. Knockdown of TUG1 reversed the high protein expression of HSP27 and the inhibition of Treg cell proportion as well as Foxp3 protein induced by Zhenbao Pill, and miR-214 inhibitor canceled the TUG1 knockdown effect. Further, miR-214 mimic reversed the inhibition of Treg cell proportion and Foxp3 protein expression by Zhenbao Pill, which was abolished by the overexpression of HSP27. The mechanism was validated in animal experiments. Conclusion: Zhenbao Pill regulated TUG1/miR-214/HSP27 signaling pathway to reduce Treg cell proportion and thus relieve acute SCI.

Identification of differentially expressed proteins in rats with spinal cord injury during the transitional phase using an iTRAQ-based quantitative analysis

BACKGROUND

Spinal cord injury (SCI) is a disease associated with high disability and mortality rates. The transitional phase from subacute phase to intermediate phase may play a major role in the process of secondary injury. Changes in protein expression levels have been shown to play key roles in many central nervous system (CNS) diseases. Nevertheless, the roles of proteins in the transitional phase of SCI are not clear.

METHODS

We examined protein expression in a rat model 2 weeks after SCI and identified differentially expressed proteins (DEPs) using isobaric tagging for relative and absolute protein quantification (iTRAQ). Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of DEPs were performed. Furthermore, we constructed a protein-protein interaction (PPI) network, and the top 10 high-degree core nodes were identified. Meanwhile, we validated protein level changes of five high-degree core regulated proteins using Western blots.

RESULTS

A total of 162 DEPs were identified between the injury group and the control, of which 101 (62.35%) were up-regulated and 61 (37.65%) were down-regulated in the transitional phase of SCI. Key molecular function, cellular components, biological process terms and pathways were identified and may be important mechanisms in the transitional phase of SCI. Alb, Calm1, Vim, Apoe, Syp, P4hb, Cd68, Eef1a2, Rab3a and Lgals3 were the top 10 high-degree core nodes. Western blot analysis performed on five of these proteins showed the same trend as iTRAQ results.

CONCLUSION

The current study may provide novel insights into how proteins regulate the pathogenesis of the transitional phase after SCI.

Conotoxin MVIIA improves cell viability and antioxidant system after spinal cord injury in rats

This study evaluates whether intrathecal MVIIA injection after spinal cord injury (SCI) elicits neuroprotective effects. The test rats were randomly distributed into six groups— sham, placebo, MVIIA 2.5 μM, MVIIA 5 μM, MVIIA 10 μM, and MVIIA 20 μM—and were administered the treatment four hours after SCI. After the optimal MVIIA dose (MVIIA 10 μM) was defined, the best time for application, one or four hours, was analyzed. Locomotor hind limb function and side effects were assessed. Forty-eight hours after the injury and immediately after euthanasia, spinal cord segments were removed from the test rats. Cell viability, reactive oxygen species, lipid peroxidation, and glutamate release were investigated. To examine the MVIIA mechanism of action, the gene expressions of pro-apoptotic (Bax, nNOS, and caspase-3, -8, -9, -12) and anti-apoptotic (Bcl-xl) factors in the spinal cord tissue samples were determined by real-time PCR, and the activities of antioxidant enzymes were also investigated. Application of intrathecal MVIIA 10 μM four hours after SCI prompted a neuroprotective effect: neuronal death decreased (22.46%), oxidative stress diminished, pro-apoptotic factors (Bax, nNOS, and caspase-3, -8) were expressed to a lesser extent, and mitochondrial viability as well as anti-apoptotic factor (Bcl-xl) expression increased. These results suggested that MVIIA provided neuroprotection through antioxidant effects. Indeed, superoxide dismutase (188.41%), and glutathione peroxidase (199.96%), reductase (193.86%), and transferase (175.93%) expressions increased. Therefore, intrathecal MVIIA (MVIIA 10 μM, 4 h) application has neuroprotective potential, and the possible mechanisms are related to antioxidant agent modulation and to intrinsic and extrinsic apoptotic pathways.

Spinal Cord Injuries in Dogs Part II: Standards of Care, Prognosis and New Perspectives

Severe spinal cord injuries (SCI), causing physical handicaps and accompanied by many serious complications, remains one of the most challenging problems in both, human and veterinary health care practices. The central nervous system in mammals does not regenerate, so the neurological deficits in a dog following SCI persists for the rest of its life and the affected animals display an image of permanent suffering. Diagnostics are based on: neurological examination, plain x-rays of vertebral column, x-rays of the vertebral column following intrathecal administration of a water-soluble contrast medium (myelography), x-rays of the vertebral column following epidural administration of a contrast medium (epidurography), computed tomography (CT) and/or magnetic resonance imaging (MRI). Currently, only limited therapeutic measures are available for the dogs with SCIs. They include: the administration of methylprednisolone sodium succinate (MPSS) during the acute stage; early spinal cord decompression; stabilisation of vertebral fractures or luxations; prevention and treatment of complications, and expert rehabilitation. Together with the progress in the understanding of pathophysiologic events occurring after SCI, different therapeutic strategies have been instituted, including the local delivery of MPSS, the utilisation of novel pharmacological agents, hypothermia, and stem/precursor cell transplantation have all been tested in the experimental models and preclinical trials with promising results. The aim of this review is the presentation of the generally accepted methods of diagnostics and management of dogs with SCIs, as well as to discuss new therapeutic modalities. The research strategy involved a PubMed, Medline (Ovid), Embase (Ovid) and ISI Web of Science literature search from January 2001 to December 2017 using the term “spinal cord injury”, in the English language literature; also references from selected papers were scanned and relevant articles included.

Microenvironment Imbalance of Spinal Cord Injury

Spinal cord injury (SCI), for which there currently is no cure, is a heavy burden on patient physiology and psychology. The microenvironment of the injured spinal cord is complicated. According to our previous work and the advancements in SCI research, ‘microenvironment imbalance’ is the main cause of the poor regeneration and recovery of SCI. Microenvironment imbalance is defined as an increase in inhibitory factors and decrease in promoting factors for tissues, cells and molecules at different times and spaces. There are imbalance of hemorrhage and ischemia, glial scar formation, demyelination and re-myelination at the tissue’s level. The cellular level imbalance involves an imbalance in the differentiation of endogenous stem cells and the transformation phenotypes of microglia and macrophages. The molecular level includes an imbalance of neurotrophic factors and their pro-peptides, cytokines, and chemokines. The imbalanced microenvironment of the spinal cord impairs regeneration and functional recovery. This review will aid in the understanding of the pathological processes involved in and the development of comprehensive treatments for SCI.

Zhenbao pill protects against acute spinal cord injury via miR-146a-5p regulating the expression of GPR17

The aim of the present study was to observe the effect of zhenbao pill on the motor function of acute spinal cord injury (ASCI) rats and the molecular mechanisms involving miR-146a-5p and G-protein-coupled receptor 17 (GPR17). ASCI rat model was established by modified Allen method, and then the rats were divided into three groups. SH-SY5Y cells were cultured overnight in hypoxia condition and transfected with miR-146a-5p mimic or miR-146a-5p inhibitor. The hind limb motor function of the rats was evaluated by Basso, Beattie, Bresnahan (BBB) scoring system. Quantitative real-time PCR (qRT-PCR) and Western blot were used to detect the expression of miR-146a-5p, GPR17, inducible nitric oxide synthase (iNOS), interleukin 1β (IL-1β), and tumor necrosis factor α (TNF-α). Neuronal apoptosis was measured using flow cytometry assay. Luciferase reporter assay was performed to determine the regulation of miR-146a-5p on GPR17. Zhenbao pill could enhance hind limb motor function and attenuate the inflammatory response caused by ASCI. Moreover, zhenbao pill increased the level of miR-146a-5p and decreased GPR17 expression in vivo and in vitro Bioinformatics software predicted that GPR17 3'-UTR had a binding site with miR-146a-5p Luciferase reporter assay showed that miR-146a-5p had a negative regulatory effect on GPR17 expression. Knockdown of miR-146a-5p could reverse the effect of zhenbao pill on the up-regulation of GPR17 induced by hypoxia, reversed the inhibitory effect of zhenbao pill on the cell apoptosis induced by hypoxia and the recovery of zhenbao pill on hind limb motor function in ASCI rats. Zhenbao pill could inhibit neuronal apoptosis by regulating miR-146a-5p/GPR17 expression, and then promoting the recovery of spinal cord function.

Geraniol promotes functional recovery and attenuates neuropathic pain in rats with spinal cord injury

Geraniol, a plant-derived monoterpene, has been extensively studied and showed a wide variety of beneficial effects. The aim of this study was to investigate the therapeutic effect of geraniol on functional recovery and neuropathic pain in rats with spinal cord injury (SCI). Rats received a clip-compression SCI and were treated with geraniol 6 h following SCI. Treatment of SCI rats with geraniol markedly improved locomotor function, and reduced sensitivity to the mechanical allodynia and thermal hyperalgesia. Treatment of SCI rats with geraniol increased NeuN-positive cells, suppressed expression of glial fibrillary acidic protein, and reduced activity of caspase-3 in the injured region. Treatment of SCI rats with geraniol reduced levels of malondialdehyde and 3-nitrotyrosine, upregulated protein expression of nuclear factor-erythroid 2-related factor 2 and heme oxygenase 1, and suppressed expression of inducible nitric oxide synthase in the injured region. In addition, treatment of SCI rats with geraniol downregulated protein expression of N-methyl-d-aspartate receptor 1 and reduced the number of CD68-positive cells and protein levels of TNF-α in the injured region. In conclusion, geraniol significantly promoted the recovery of neuronal function and attenuated neuropathic pain after SCI.

Upregulation of PTP1B After Rat Spinal Cord Injury

Protein tyrosine phosphatase 1B (PTP1B), a member of the protein tyrosine phosphatase family, attaches to the endoplasmic reticulum (ER) via its C-terminal tail. Previous studies have reported that PTP1B participates in various signal transduction pathways in many human diseases, including diabetes, cancers, osteoporosis, and obesity. It also plays an important role in the ER stress. ER stress induced by spinal cord injury (SCI) was reported to result in cell apoptosis. Till now, the role of PTP1B in the injury of the central nervous system remains unknown. In the present study, we built an adult rat SCI model to investigate the potential role of PTP1B in SCI. Western blot analysis detected a notable alteration of PTP1B expression after SCI. Immunohistochemistry indicated that PTP1B expressed at a low level in the normal spinal cord and greatly increased after SCI. Double immunofluorescence staining revealed that PTP1B immunoreactivity was predominantly increased in neurons following SCI. In addition, SCI resulted in a significant alteration in the level of active caspase-3, caspase-12, and 153/C/EBP homologous transcription factor protein, which were correlated with the upregulation of PTP1B. Co-localization of PTP1B/active caspase-3 was also detected in neurons. Taken together, our findings elucidated the PTP1B expression in the SCI for the first time. These results suggested that PTP1B might be deeply involved in the injury response and probably played an important role in the neuro-pathological process of SCI.

Systemic effects induced by intralesional injection of ω-conotoxin MVIIC after spinal cord injury in rats

Background

Calcium channel blockers such as conotoxins have shown a great potential to reduce brain and spinal cord injury. MVIIC neuroprotective effects analyzed in in vitro models of brain and spinal cord ischemia suggest a potential role of this toxin in preventing injury after spinal cord trauma. However, previous clinical studies with MVIIC demonstrated that clinical side effects might limit the usefulness of this drug and there is no research on its systemic effects. Therefore, the present study aimed to investigate the potential toxic effects of MVIIC on organs and to evaluate clinical and blood profiles of rats submitted to spinal cord injury and treated with this marine toxin. Rats were treated with placebo or MVIIC (at doses of 15, 30, 60 or 120 pmol) intralesionally following spinal cord injury. Seven days after the toxin administration, kidney, brain, lung, heart, liver, adrenal, muscles, pancreas, spleen, stomach, and intestine were histopathologically investigated. In addition, blood samples collected from the rats were tested for any hematologic or biochemical changes.

Results

The clinical, hematologic and biochemical evaluation revealed no significant abnormalities in all groups, even in high doses. There was no significant alteration in organs, except for degenerative changes in kidneys at a dose of 120 pmol.

Conclusions

These findings suggest that MVIIC at 15, 30 and 60 pmol are safe for intralesional administration after spinal cord injury and could be further investigated in relation to its neuroprotective effects. However, 120 pmol doses of MVIIC may provoke adverse effects on kidney tissue.

Necroptosis inhibitor necrostatin-1 promotes cell protection and physiological function in traumatic spinal cord injury

Spinal cord injury (SCI) is a common and serious trauma which lacks efficient treatment. Inhibition of cell death in the trauma area is important for spinal cord protection during this process. In this study, necroptosis inhibitor necrostatin-1 (Nec-1) was used to treat SCI rats, to investigate the role of Nec-1 in the recovery of SCI. Nec-1 was found to reduce lesions, cytokines and reactive oxygen species (ROS), improve pathological conditions and blood supply in the spinal cord trauma area. Further study indicated that Nec-1 could inhibit necroptosis by inhibiting RIP1/3-MLKL recruitment and inhibit apoptosis by inhibiting Caspase 3 and Bax while activating Bcl-2. Ethological performance of SCI rats confirmed improvement and protection of physiological function by Nec-1. Nec-1 as a potential treatment for SCI warrants further study. To our knowledge, this is the first study on the role of Nec-1 in the treatment of traumatic SCI. Our research also found inhibition effects of Nec-1 on apoptosis, not only necroptosis - as reported by most publications.

Bone marrow stromal cells inhibit caspase-12 expression in rats with spinal cord injury

The mechanisms underlying the potentially beneficial effect of bone marrow stem cells (BMSCs) on spinal cord injury (SCI) are unknown. Therefore, the aim of the present study was to explore the protective effect of BMSCs in rats with SCI. A total of 45 adult male Sprague-Dawley rats were randomly divided into three groups; the SCI group (n=15), the BMSC group (n=15) and the sham-operation group (n=15). In the SCI and BMSC treatment groups, a modified Allen’s weight-drop technique was used to induce SCI. The BMSC treatment group received an injection of BMSCs using a microneedle into the epicenter of the spinal cord 24 h after injury. Rats in the sham-operation group were not subjected to SCI; however, the corresponding vertebral laminae were removed. Seven days after transplantation, a rapid recovery was observed in the Basso, Beattie and Bresnahan (BBB) scores of the BMSC treatment group, whereas the BBB scores in the SCI group remained low (P<0.05). Caspase-12 expression in the SCI group was increased compared with that in the sham-operation group, whereas caspase-12 expression was attenuated 24 h after transplantation in the BMSC treatment group (P<0.05). In conclusion, the transplantation of BMSCs may improve locomotor function and attenuate caspase-12 expression following SCI. Therefore, it is likely to be an effective strategy for preventing severe injury of the spinal cord.

C/EBP homologous protein (CHOP) mediates neuronal apoptosis in rats with spinal cord injury

Spinal cord injury (SCI) is a severe health problem and the mechanism involved remains elusive. The aim of the present study was to elucidate the role of C/EBP homologous protein (CHOP), a prominent protein of the endoplasmic reticulum (ER) stress-mediated apoptosis in SCI. A total of 20 adult male Sprague-Dawley rats were divided into two groups at random, ten rats were subjected to a modified Allen's test (using a weight-drop device) to induce a SCI model and the remaining ten rats only had the corresponding vertebral lamina removed with no injury and served as the sham-operated group. Pathological changes in the spinal cord were observed 12 h after injury by hematoxylin and eosin staining and TUNEL staining was performed to visualize apoptotic cells. The expression of CHOP was also detected by immunohistochemistry and quantitative real-time reverse transcription-polymerase chain reaction. The results showed that a typical apoptotic morphology, namely the increased the number of TUNEL-positive cells in the injured spinal cord. The expression levels of CHOP in the rats with SCI were increased compared with the sham-operated rats (P<0.05). These results revealed that CHOP-mediated ER stress-induced apoptosis may be involved in SCI.