Spinal Cord Injury: Pathophysiology, Multimolecular Interactions, and Underlying Recovery Mechanisms

Molecular Aspects of Hypoxic Stress Effects in Chronic Ethanol Exposure of Neuronal Cells

Experimental models of a clinical, pathophysiological context are used to understand molecular mechanisms and develop novel therapies. Previous studies revealed better outcomes for spinal cord injury chronic ethanol-consuming patients. This study evaluated cellular and molecular changes in a model mimicking spinal cord injury (hypoxic stress induced by treatment with deferoxamine or cobalt chloride) in chronic ethanol-consuming patients (ethanol-exposed neural cultures (SK-N-SH)) in order to explain the clinical paradigm of better outcomes for spinal cord injury chronic ethanol-consuming patients. The results show that long-term ethanol exposure has a cytotoxic effect, inducing apoptosis. At 24 h after the induction of hypoxic stress (by deferoxamine or cobalt chloride treatments), reduced ROS in long-term ethanol-exposed SK-N-SH cells was observed, which might be due to an adaptation to stressful conditions. In addition, the HIF-1α protein level was increased after hypoxic treatment of long-term ethanol-exposed cells, inducing fluctuations in its target metabolic enzymes proportionally with treatment intensity. The wound healing assay demonstrated that the cells recovered after stress conditions, showing that the ethanol-exposed cells that passed the acute step had the same proliferation profile as the cells unexposed to ethanol. Deferoxamine-treated cells displayed higher proliferative activity than the control cells in the proliferation-migration assay, emphasizing the neuroprotective effect. Cells have overcome the critical point of the alcohol-induced traumatic impact and adapted to ethanol (a chronic phenomenon), sustaining the regeneration process. However, further experiments are needed to ensure recovery efficiency is more effective in chronic ethanol exposure.

Depression mediated the relationships between precentral-subcortical causal links and motor recovery in spinal cord injury patients

Depression after brain damage may impede the motivation and consequently influence the motor recovery after spinal cord injury (SCI); however, the neural mechanism underlying the psychological effects remains unclear. This study aimed to examine the casual connectivity changes of the emotion-motivation-motor circuit and the potential mediating effects of depression on motor recovery after SCI. Using the resting-state functional magnetic resonance imaging data of 35 SCI patients (24 good recoverers, GR and 11 poor recoverers, PR) and 32 healthy controls (HC), the results from the conditional Granger causality (GC) analysis demonstrated that the GR group exhibited sparser emotion-motivation-motor GC network compared with the HC and PR groups, though the in-/out-degrees of the emotion subnetwork and the motor subnetwork were relatively balanced in the HC and GR group. The PR group showed significantly inhibitory causal links from amygdala to supplementary motor area and from precentral gyrus to nucleus accumbens compared with GR group. Further mediation analysis revealed the indirect effect of the 2 causal connections on motor function recovery via depression severity. Our findings provide further evidence of abnormal causal connectivity in emotion-motivation-motor circuit in SCI patients and highlight the importance of emotion intervention for motor function recovery after SCI.

Ang-(1-7)/MasR axis promotes functional recovery after spinal cord injury by regulating microglia/macrophage polarization

BACKGROUND

Inflammatory response is an essential part of secondary injury after spinal cord injury (SCI). During this period, the injury may be exacerbated through the release of a large number of inflammatory factors and the polarization of infiltrating macrophages and microglia towards M1. Ang-(1-7), mainly generated by Ang II via angiotensin-converting enzyme 2 (ACE2), can specifically bind to the G protein-coupled receptor Mas (MasR) and plays an important role in regulating inflammation and alleviating oxidative stress.

METHODS

We aimed to investigate whether activating the Ang-(1-7)/MasR axis in rats after SCI can regulate local neuroinflammation to achieve functional recovery and obtain its potential mechanism. MasR expression of bone marrow-derived macrophages was determined by Western blot. Immunofluorescence, Western blot, Flow cytometry, and RT-qPCR were applied to evaluate the polarization of Ang-(1-7) on macrophages and the regulation of inflammatory cytokines. Previous evaluation of the spinal cord and bladder after SCI was conducted by hematoxylin-eosin staining, Basso, Beattie, and Bresnahan (BBB) score, inclined plate test, electrophysiology, and catwalk were used to evaluate the functional recovery of rats.

RESULTS

MasR expression increased in macrophages under inflammatory conditions and further elevated after Ang-(1-7) treatment. Both in vivo and in vitro results confirmed that Ang-(1-7) could regulate the expression of inflammatory cytokines by down-regulating proinflammatory cytokines and up-regulating anti-inflammatory cytokines, and bias the polarization direction of microglia/macrophages to M2 phenotypic. After SCI, Ang-(1-7) administration in situ led to better histological and functional recovery in rats, and this recovery at least partly involved the TLR4/NF-κB signaling pathway.

CONCLUSION

As shown in our data, activating Ang-(1-7)/MasR axis can effectively improve the inflammatory microenvironment after spinal cord injury, promote the polarization of microglia/macrophages towards the M2 phenotype, and finally support the recovery of motor function. Therefore, we suggest using Ang-(1-7) as a feasible treatment strategy for spinal cord injury to minimize the negative consequences of the inflammatory microenvironment after spinal cord injury.

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.

Construction of a searchable database for gene expression changes in spinal cord injury experiments

Spinal cord injury (SCI) is a debilitating disease resulting in an estimated 18,000 new cases in the United States on an annual basis. Significant behavioral research on animal models has led to a large amount of data, some of which has been catalogued in the Open Data Commons for Spinal Cord Injury (ODC-SCI). More recently, high throughput sequencing experiments have been utilized to understand molecular mechanisms associated with SCI, with nearly 6,000 samples from over 90 studies available in the Sequence Read Archive. However, to date, no resource is available for efficiently mining high throughput sequencing data from SCI experiments. Therefore, we have developed a protocol for processing RNA-Seq samples from high-throughput sequencing experiments related to SCI resulting in both raw and normalized data that can be efficiently mined for comparisons across studies as well as homologous discovery across species. We have processed 1,196 publicly available RNA-seq samples from 50 bulk RNA-Seq studies across nine different species, resulting in an SQLite database that can be used by the SCI research community for further discovery. We provide both the database as well as a web-based front-end that can be used to query the database for genes of interest, differential gene expression, genes with high variance, and gene set enrichments.

MicroRNAs in spinal cord injury: A narrative review

Spinal cord injury (SCI) is a global medical problem with high disability and mortality rates. At present, the diagnosis and treatment of SCI are still lacking. Spinal cord injury has a complex etiology, lack of diagnostic methods, poor treatment effect and other problems, which lead to the difficulty of spinal cord regeneration and repair, and poor functional recovery. Recent studies have shown that gene expression plays an important role in the regulation of SCI repair. MicroRNAs (miRNAs) are non-coding RNA molecules that target mRNA expression in order to silence, translate, or interfere with protein synthesis. Secondary damage, such as oxidative stress, apoptosis, autophagy, and inflammation, occurs after SCI, and differentially expressed miRNAs contribute to these events. This article reviews the pathophysiological mechanism of miRNAs in secondary injury after SCI, focusing on the mechanism of miRNAs in secondary neuroinflammation after SCI, so as to provide new ideas and basis for the clinical diagnosis and treatment of miRNAs in SCI. The mechanisms of miRNAs in neurological diseases may also make them potential biomarkers and therapeutic targets for spinal cord injuries.

Current Status of Polysaccharides-Based Drug Delivery Systems for Nervous Tissue Injuries Repair

Neurological disorders affecting both CNS and PNS still represent one of the most critical and challenging pathologies, therefore many researchers have been focusing on this field in recent decades. Spinal cord injury (SCI) and peripheral nerve injury (PNI) are severely disabling diseases leading to dramatic and, in most cases, irreversible sensory, motor, and autonomic impairments. The challenging pathophysiologic consequences involved in SCI and PNI are demanding the development of more effective therapeutic strategies since, as yet, a therapeutic strategy that can effectively lead to a complete recovery from such pathologies is not available. Drug delivery systems (DDSs) based on polysaccharides have been receiving more and more attention for a wide range of applications, due to their outstanding physical-chemical properties. This review aims at providing an overview of the most studied polysaccharides used for the development of DDSs intended for the repair and regeneration of a damaged nervous system, with particular attention to spinal cord and peripheral nerve injury treatments. In particular, DDSs based on chitosan and their association with alginate, dextran, agarose, cellulose, and gellan were thoroughly revised.

Photobiomodulation promotes spinal cord injury repair by inhibiting macrophage polarization through lncRNA TUG1-miR-1192/TLR3 axis

BACKGROUND

Secondary spinal cord injury (SCI) often causes the aggravation of inflammatory reaction and nerve injury, which affects the recovery of motor function. Bone-marrow-derived macrophages (BMDMs) were recruited to the injured area after SCI, and the M1 polarization is the key process for inducing inflammatory response and neuronal apoptosis. We previously showed that photobiomodulation (PBM) can inhibit the polarization of M1 phenotype of BMDMs and reduce inflammation, but the underlying mechanisms are unclear. The purpose of this study is to explore the potential target and mechanism of PBM in treating SCI.

METHODS

Transcriptome sequencing and bioinformatics analysis showed that long noncoding RNA taurine upregulated gene 1 (lncRNA TUG1) was a potential target of PBM. The expression and specific mechanism of lncRNA TUG1 were detected by qPCR, immunofluorescence, flow cytometry, western blotting, fluorescence in situ hybridization, and luciferase assay. The Basso mouse scale (BMS) and gait analysis were used to evaluate the recovery of motor function in mice.

RESULTS

Results showed that lncRNA TUG1 may be a potential target of PBM, regulating the polarization of BMDMs, inflammatory response, and the axial growth of DRG. Mechanistically, TUG1 competed with TLR3 for binding to miR-1192 and attenuated the inhibitory effect of miR-1192 on TLR3. This effect protected TLR3 from degradation, enabling the high expression of TLR3, which promoted the activation of downstream NF-κB signal and the release of inflammatory cytokines. In vivo, PBM treatment could reduce the expression of TUG1, TLR3, and inflammatory cytokines and promoted nerve survival and motor function recovery in SCI mice.

CONCLUSIONS

Our study clarified that the lncRNA TUG1/miR-1192/TLR3 axis is an important pathway for PBM to inhibit M1 macrophage polarization and inflammation, which provides theoretical support for its clinical application in patients with SCI.

Research progress of hydrogels as delivery systems and scaffolds in the treatment of secondary spinal cord injury

Secondary spinal cord injury (SSCI) is the second stage of spinal cord injury (SCI) and involves vasculature derangement, immune response, inflammatory response, and glial scar formation. Bioactive additives, such as drugs and cells, have been widely used to inhibit the progression of secondary spinal cord injury. However, the delivery and long-term retention of these additives remain a problem to be solved. In recent years, hydrogels have attracted much attention as a popular delivery system for loading cells and drugs for secondary spinal cord injury therapy. After implantation into the site of spinal cord injury, hydrogels can deliver bioactive additives in situ and induce the unidirectional growth of nerve cells as scaffolds. In addition, physical and chemical methods can endow hydrogels with new functions. In this review, we summarize the current state of various hydrogel delivery systems for secondary spinal cord injury treatment. Moreover, functional modifications of these hydrogels for better therapeutic effects are also discussed to provide a comprehensive insight into the application of hydrogels in the treatment of secondary spinal cord injury.

Architecture-Engineered Electrospinning Cascade Regulates Spinal Microenvironment to Promote Nerve Regeneration

The inflammatory cascade after spinal cord injury (SCI) causes necrotizing apoptosis of local stem cells, which limits nerve regeneration. Therefore, coordinating the inflammatory immune response and neural stem cell (NSC) functions is key to promoting the recovery of central nervous system function. In this study, a hydrogel "perfusion" system and electrospinning technology are integrated, and a "concrete" composite support for the repair of nerve injuries is built. The hydrogel's hydrophilic properties activate macrophage integrin receptors to mediate polarization into anti-inflammatory subtypes and cause a 10% increase in polarized M2 macrophages, thus reprogramming the SCI immune microenvironment. Programmed stromal cell-derived factor-1α and brain-derived neurotrophic factor released from the composite increase recruitment and neuronal differentiation of NSCs by approximately four- and twofold, respectively. The fiber system regulates the SCI immune inflammatory microenvironment, recruits endogenous NSCs, promotes local blood vessel germination and maturation, and improves nerve function recovery in a rat SCI model. In conclusion, the engineering fiber composite improves the local inflammatory response. It promotes nerve regeneration through a hydrophilic programmed cytokine-delivery system, which further improves and supplements the immune response mechanism regulated by the inherent properties of the biomaterial. The new fiber composite may serve as a new treatment approach for SCI.

Adalimumab combined with erythropoietin improves recovery from spinal cord injury by suppressing microglial M1 polarization-mediated neural inflammation and apoptosis

OBJECTIVE

Adalimumab (ADM), a humanized antibody against tumour necrosis factor (TNF), is widely applied in treating inflammatory and autoimmune diseases, but its usage in spinal cord injury (SCI) is rarely reported. Hence, this study aimed to explore the effect of ADM with or without erythropoietin (EPO) on microglial polarization, neuroinflammation, neural apoptosis, and functional recovery in SCI.

METHODS

Primary microglia were stimulated with lipopolysaccharide (LPS) and then treated with ADM, EPO, or ADM combined with EPO. Then, primary neurons were incubated in the microglial culture medium. SCI rats were established and then treated with ADM, EPO or ADM combined with EPO.

RESULTS

ADM suppressed LPS-induced microglial M1 polarization, as reflected by downregulated iNOS and CD86 expression, and neuroinflammation, as reflected by decreased TNF-α, IL-1β, and IL-6 expression, in a dose-dependent manner. Moreover, ADM inhibited microglia-induced neural apoptosis, as reflected by TUNEL assay results and the expression of apoptotic markers (C-Caspase3 and Bcl2), in a dose-dependent manner. EPO monotherapy displayed an effect similar to that of ADM monotherapy. Furthermore, ADM combined with EPO therapy exhibited greater effects than either monotherapy in terms of inhibiting microglial M1 polarization, neuroinflammation, and neural apoptosis. In vivo experiments confirmed the findings of the in vitro experiments and showed that ADM combined with EPO improved SCI functional recovery and neural injury compared with monotherapy.

CONCLUSION

ADM combined with EPO improves recovery from SCI by suppressing microglial M1 polarization-mediated neural inflammation and apoptosis.

Induced pluripotent stem cells as natural biofactories for exosomes carrying miR-199b-5p in the treatment of spinal cord injury

Background: Induced pluripotent stem cells-derived exosomes (iPSCs-Exo) can effectively treat spinal cord injury (SCI) in mice. But the role of iPSCs-Exo in SCI mice and its molecular mechanisms remain unclear. This research intended to study the effects and molecular mechanism of iPSCs-Exo in SCI mice models. Methods: The feature of iPSCs-Exo was determined by transmission electron microscope (TEM), nanoparticle tracking analysis (NTA), and western blot. The effects of iPSCs-Exo in the SCI mice model were evaluated by Basso Mouse Scale (BMS) scores and H&E staining. The roles of iPSCs-Exo and miR-199b-5p in LPS-treated BMDM were verified by immunofluorescence, RT-qPCR, and Cytokine assays. The target genes of miR-199b-5p were identified, and the function of miR-199b-5p and its target genes on LPS-treated BMDM was explored by recuse experiment. Results: iPSCs-Exo improved motor function in SCI mice model in vivo, shifted the polarization from M1 macrophage to M2 phenotype, and regulated related inflammatory factors expression to accelerate the SCI recovery in LPS-treated BMDM in vitro. Meanwhile, miR-199b-5p was a functional player of iPSCs-Exo, which could target hepatocyte growth factor (Hgf). Moreover, miR-199b-5p overexpression polarized M1 macrophage into M2 phenotype and promoted neural regeneration in SCI. The rescue experiments confirmed that miR-199b-5p induced macrophage polarization and SCI recovery by regulating Hgf and Phosphoinositide 3-kinase (PI3K) signaling pathways. Conclusion: The miR-199b-5p-bearing iPSCs-Exo might become an effective method to treat SCI.

Macrophages play a leading role in determining the direction of astrocytic migration in spinal cord injury via ADP-P2Y1R axis

After spinal cord injury (SCI), inflammatory cells such as macrophages infiltrate the injured area, and astrocytes migrate, forming a glial scar around macrophages. The glial scar inhibits axonal regeneration, resulting in significant permanent disability. However, the mechanism by which glial scar-forming astrocytes migrate to the injury site has not been clarified. Here we show that migrating macrophages attract reactive astrocytes toward the center of the lesion after SCI. Chimeric mice with bone marrow lacking IRF8, which controls macrophage centripetal migration after SCI, showed widely scattered macrophages in injured spinal cord with the formation of a huge glial scar around the macrophages. To determine whether astrocytes or macrophages play a leading role in determining the directions of migration, we generated chimeric mice with reactive astrocyte-specific Socs3 ^-/- mice, which showed enhanced astrocyte migration, and bone marrow from IRF8 ^-/- mice. In this mouse model, macrophages were widely scattered, and a huge glial scar was formed around the macrophages as in wild-type mice that were transplanted with IRF8 ^-/ bone marrow. In addition, we revealed that macrophage-secreted ATP-derived ADP attracts astrocytes via the P2Y1 receptor. Our findings revealed a mechanism in which migrating macrophages attracted astrocytes and affected the pathophysiology and outcome after SCI.

Immune response following traumatic spinal cord injury: Pathophysiology and therapies

Traumatic spinal cord injury (SCI) is a devastating condition that is often associated with significant loss of function and/or permanent disability. The pathophysiology of SCI is complex and occurs in two phases. First, the mechanical damage from the trauma causes immediate acute cell dysfunction and cell death. Then, secondary mechanisms of injury further propagate the cell dysfunction and cell death over the course of days, weeks, or even months. Among the secondary injury mechanisms, inflammation has been shown to be a key determinant of the secondary injury severity and significantly worsens cell death and functional outcomes. Thus, in addition to surgical management of SCI, selectively targeting the immune response following SCI could substantially decrease the progression of secondary injury and improve patient outcomes. In order to develop such therapies, a detailed molecular understanding of the timing of the immune response following SCI is necessary. Recently, several studies have mapped the cytokine/chemokine and cell proliferation patterns following SCI. In this review, we examine the immune response underlying the pathophysiology of SCI and assess both current and future therapies including pharmaceutical therapies, stem cell therapy, and the exciting potential of extracellular vesicle therapy.

The Application of Biomaterials in Spinal Cord Injury

The spinal cord and the brain form the central nervous system (CNS), which is the most important part of the body. However, spinal cord injury (SCI) caused by external forces is one of the most difficult types of neurological injury to treat, resulting in reduced or even absent motor, sensory and autonomic functions. It leads to the reduction or even disappearance of motor, sensory and self-organizing nerve functions. Currently, its incidence is increasing each year worldwide. Therefore, the development of treatments for SCI is urgently needed in the clinic. To date, surgery, drug therapy, stem cell transplantation, regenerative medicine, and rehabilitation therapy have been developed for the treatment of SCI. Among them, regenerative biomaterials that use tissue engineering and bioscaffolds to transport cells or drugs to the injured site are considered the most promising option. In this review, we briefly introduce SCI and its molecular mechanism and summarize the application of biomaterials in the repair and regeneration of tissue in various models of SCI. However, there is still limited evidence about the treatment of SCI with biomaterials in the clinic. Finally, this review will provide inspiration and direction for the future study and application of biomaterials in the treatment of SCI.

Cardiac autonomic modulation in response to postural transition during a virtual reality task in individuals with spinal cord injury: A cross-sectional study

PURPOSE

The postural transition from sitting to standing is a moment of dysautonomic occurrence in individuals with Spinal Cord Injury (SCI). Different tools can be used to minimize this event, such as virtual reality. Thus, we aimed to analyze cardiac autonomic modulation in individuals with SCI during postural transition from the sitting to orthostatism position using a cognitive virtual reality (VR) task.

METHODS

Individuals with and without SCI were positioned on the Easy Stand® device, sitting at rest, at 0° considering the angle between the seat and the floor, elevation at 45°, and orthostatism at 90°, for 5 minutes in each position. Heart rate variability (HRV) measures of sympathovagal balance were collected (heart rate receiver: Polar V800). The groups were subdivided into two groups, one that performed VR as an intervention during the postural angle changes and another group that did not perform VR.

RESULTS

We evaluated 76 individuals, 40 with a medical diagnosis of SCI and 36 who composed the able-bodied control group without SCI, matched by age and sex. The HRV results showed that the SCI group who performed the task in VR demonstrated no significant difference in parasympathetic activation and global variability between the sitting versus 90° positions. There was better sympathovagal balance in SCI and able-bodied control groups who performed the VR task between the sitting versus 90° positions.

CONCLUSION

The use of a VR task seems to contribute to better sympathovagal balance, with the potential to reduce dysautonomia during postural changes.

miR-129-5p Induces Cell Apoptosis and Inhibits Inflammation by Inflammatory Signaling to Alleviate Spinal Cord Injury (SCI)

Spinal cord injury (SCI) is a spinal cord nerve dysfunction secondary to trauma. Until now, still no appropriate drug with unclear etiology. Therefore, it is to develop effective SCI treatment methods. Herein, we intended to detect the impact of miR-129-5p in SCI After establishment of a mouse SCI model, the animals received intrathecal injection of agomir-miR-129-5p or normal saline. Then, the miR-129-5p’s effect was evaluated by assessing motor function, spinal cord tissue edema, apoptosis and inflammation of mice upon treatments and potential targeted pathways of the miRNA were detected. Overexpressed miR-129-5p facilitated the wound healing with less spare tissue and water content. Additionally, overexpressed miR-129-5p suppressed the in vivo inflammation with decreased apoptotic rate of neurons. As SCI induced increased expression of HMGB1, TLR4, and NF-κB in tissues, but the presence of miR-129-5p reversed the expressions. Collectively, this study elucidate miR-129-5p significantly improves inflammatory response and apoptosis, thereby improving the condition of SCI. These findings might provide a new theory for the disorder, and promote the research progress on the disease.

The Importance of Using Exosome-Loaded miRNA for the Treatment of Spinal Cord Injury

Spinal cord injury (SCI) is a major traumatic disease of the central nervous system characterized by high rates of disability and mortality. Many studies have shown that SCI can be divided into the two stages of primary and secondary injury. Primary injury leads to pathophysiological changes, while consequential injury is even more fatal, including a series of harmful reactions that expand the scope and degree of SCI. Because the pathological process of SCI is highly complex, there is still no clear and effective clinical treatment strategy. Exosomes, membrane-bound extracellular vesicles (EVs) with a diameter of 30-200 nm, have emerged as an ideal vector to deliver therapeutic molecules. At the same time, increasing numbers of studies have shown that miRNAs play a momentous role in the process of SCI. In recent studies, researchers have adopted exosomes as carriers of miRNAs with potential therapeutic effects in SCI. In this review, we summarize relevant articles describing exosomes as miRNA carriers for SCI, after which we discuss further implications and perspectives of this novel treatment modality.

Role of inflammation in neurological damage and regeneration following spinal cord injury and its therapeutic implications

Spinal cord injury (SCI) is an incurable trauma that frequently results in partial or complete loss of motor and sensory function. Massive neurons are damaged after the initial mechanical insult. Secondary injuries, which are triggered by immunological and inflammatory responses, also result in neuronal loss and axon retraction. This results in defects in the neural circuit and a deficiency in the processing of information. Although inflammatory responses are necessary for spinal cord recovery, conflicting evidence of their contributions to specific biological processes have made it difficult to define the specific role of inflammation in SCI. This review summarizes our understanding of the complex role of inflammation in neural circuit events following SCI, such as cell death, axon regeneration and neural remodeling. We also review the drugs that regulate immune responses and inflammation in the treatment of SCI and discuss the roles of these drugs in the modulation of neural circuits. Finally, we provide evidence about the critical role of inflammation in facilitating spinal cord neural circuit regeneration in zebrafish, an animal model with robust regenerative capacity, to provide insights into the regeneration of the mammalian central nervous system.

Research Progress of Long Non-coding RNAs in Spinal Cord Injury

Spinal cord injury (SCI) can result in a partial or complete loss of motor and sensory function below the injured segment, which has a significant impact on patients' quality of life and places a significant social burden on them. Long non-coding RNA (LncRNA) is a 200-1000 bp non-coding RNA that has been shown to have a key regulatory role in the progression of a variety of neurological illnesses. Many studies have demonstrated that differentially expressed LncRNAs following spinal cord injury can participate in inflammatory damage, apoptosis, and nerve healing by functioning as competitive endogenous RNA (ceRNA); at the same time, it has a significant regulatory effect on sequelae such neuropathic pain. As a result, we believe that LncRNAs could be useful as a molecular regulatory target in the diagnosis, treatment, and prognosis of spinal cord injury.

Multiple strategies enhance the efficacy of MSCs transplantation for spinal cord injury

Spinal cord injury (SCI) is a serious complication of the central nervous system (CNS) after spine injury, often resulting in severe sensory, motor, and autonomic dysfunction below the level of injury. To date, there is no effective treatment strategy for SCI. Recently, stem cell therapy has brought hope to patients with neurological diseases. Mesenchymal stem cells (MSCs) are considered to be the most promising source of cellular therapy after SCI due to their immunomodulatory, neuroprotective and angiogenic potential. Considering the limited therapeutic effect of MSCs due to the complex pathophysiological environment following SCI, this paper not only reviews the specific mechanism of MSCs to facilitate SCI repair, but also further discusses the research status of these pluripotent stem cells combined with other therapeutic approaches to promote anatomical and functional recovery post-SCI.

The mechanism of human neural stem cell secretomes improves neuropathic pain and locomotor function in spinal cord injury rat models: through antioxidant, anti-inflammatory, anti-matrix degradation, and neurotrophic activities

Background

Globally, spinal cord injury (SCI) results in a big burden, including 90% suffering permanent disability, and 60%-69% experiencing neuropathic pain. The main causes are oxidative stress, inflammation, and degeneration. The efficacy of the stem cell secretome is promising, but the role of human neural stem cell (HNSC)-secretome in neuropathic pain is unclear. This study evaluated how the mechanism of HNSC-secretome improves neuropathic pain and locomotor function in SCI rat models through antioxidant, anti-inflammatory, anti-matrix degradation, and neurotrophic activities.

Methods

A proper experimental study investigated 15 Rattus norvegicus divided into normal, control, and treatment groups (30 μL HNSC-secretome, intrathecal in the level of T10, three days post-traumatic SCI). Twenty-eight days post-injury, specimens were collected, and matrix metalloproteinase (MMP)-9, F2-Isoprostanes, tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β, and brain derived neurotrophic factor (BDNF) were analyzed. Locomotor recovery was evaluated via Basso, Beattie, and Bresnahan scores. Neuropathic pain was evaluated using the Rat Grimace Scale.

Results

The HNSC-secretome could improve locomotor recovery and neuropathic pain, decrease F2-Isoprostane (antioxidant), decrease MMP-9 and TNF-α (anti-inflammatory), as well as modulate TGF-β and BDNF (neurotrophic factor). Moreover, HNSC-secretomes maintain the extracellular matrix of SCI by reducing the matrix degradation effect of MMP-9 and increasing the collagen formation effect of TGF-β as a resistor of glial scar formation.

Conclusions

The present study demonstrated the mechanism of HNSC-secretome in improving neuropathic pain and locomotor function in SCI through antioxidant, anti-inflammatory, anti-matrix degradation, and neurotrophic activities.

Targeting autophagy process in center nervous trauma

The central nervous system (CNS) is the primary regulator of physiological activity, and when CNS is compromised, its physical functions are affected. Spinal cord injury (SCI) and traumatic brain injury (TBI) are common trauma in CNS that are difficult to recover from, with a higher global disability and mortality rate. Autophagy is familiar to almost all researchers due to its role in regulating the degradation and recycling of cellular defective or incorrect proteins and toxic components, maintaining body balance and regulating cell health and function. Emerging evidence suggests it has a broad and long-lasting impact on pathophysiological process such as oxidative stress, inflammation, apoptosis, and angiogenesis, involving the alteration of autophagy marker expression and function recovery. Changes in autophagy level are considered a potential therapeutic strategy and have shown promising results in preclinical studies for neuroprotection following traumatic brain injury. However, the relationship between upward or downward autophagy and functional recovery following SCI or TBI is debatable. This article reviews the regulation and role of autophagy in repairing CNS trauma and the intervention effects of autophagy-targeted therapeutic agents to find more and better treatment options for SCI and TBI patients.

Role of Transcription Factor Nrf2 in Pyroptosis in Spinal Cord Injury by Regulating GSDMD

Spinal cord injury (SCI) is a prevalent disease that debilitates millions of people. Nuclear factor E2-related factor 2 (Nrf2) is an important regulator of SCI. The current study sought to elaborate on the effects of Nrf2 on gasdermin D (GSDMD)-mediated microglia pyroptosis to repair SCI. The SCI rat model was established via the percussion of the T10 spinal cord and in vitro SCI model was established on BV-2 cells via lipopolysaccharide (LPS)/adenosine triphosphate (ATP) treatment. Nrf2 expression in SCI rats and BV-2 cells was overexpressed via pcDNA3.1-Nrf2 injection. Functional assays were carried out to evaluate SCI rat pathological injury, BV-2 cell viability, the release of lactate dehydrogenase (LDH), and pyroptotic factors. The binding relations of Nrf2 and microRNA (miR)-146a and miR-146a and GSDMD were verified. BV-2 pyroptosis was analyzed after the combined experiment of miR-146a-inhibitor and pcDNA3.1-GSDMD. Our experiments revealed that Nrf2 was downregulated in SCI, and Nrf2 overexpression relieved SCI pathological injury, promoted BV-2 cell viability, inhibited the release of LDH, and repressed pyroptosis. Mechanically, Nrf2 bound to the miR-146a promoter and promoted miR-146a expression, and miR-146a targeted GSDMD transcription. Rescue experiments revealed that miR-146a knockdown or GSDMD overexpression annulled the inhibitory function of Nrf2 overexpression in LPS/ATP-induced microglia pyroptosis. Overall, our findings initially highlighted that Nrf2 inhibited GSDMD-mediated microglia pyroptosis and accelerated SCI repair by repressing miR-146a.

TiO2-Nanowired Delivery of Chinese Extract of Ginkgo biloba EGb-761 and Bilobalide BN-52021 Enhanced Neuroprotective Effects of Cerebrolysin Following Spinal Cord Injury at Cold Environment

Military personnel during combat or peacekeeping operations are exposed to extreme climates of hot or cold environments for longer durations. Spinal cord injury is quite common in military personnel following central nervous system (CNS) trauma indicating a possibility of altered pathophysiological responses at different ambient temperatures. Our previous studies show that the pathophysiology of brain injury is exacerbated in animals acclimated to cold (5 °C) or hot (30 °C) environments. In these diverse ambient temperature zones, trauma exacerbated oxidative stress generation inducing greater blood-brain barrier (BBB) permeability and cell damage. Extracts of Ginkgo biloba EGb-761 and BN-52021 treatment reduces brain pathology following heat stress. This effect is further improved following TiO₂ nanowired delivery in heat stress in animal models. Several studies indicate the role of EGb-761 in attenuating spinal cord induced neuronal damages and improved functional deficit. This is quite likely that these effects are further improved following nanowired delivery of EGb-761 and BN-52021 with cerebrolysin-a balanced composition of several neurotrophic factors and peptide fragments in spinal cord trauma. In this review, TiO₂ nanowired delivery of EGb-761 and BN-52021 with nanowired cerebrolysin is examined in a rat model of spinal cord injury at cold environment. Our results show that spinal cord injury aggravates cord pathology in cold-acclimated rats and nanowired delivery of EGb-761 and BN-52021 with cerebrolysin significantly induced superior neuroprotection, not reported earlier.

Application of platelet-rich plasma in spinal surgery

With the aging of the population and changes in lifestyle, the incidence of spine-related diseases is increasing, which has become a major global public health problem; this results in a huge economic burden on the family and society. Spinal diseases and complications can lead to loss of motor, sensory, and autonomic functions. Therefore, it is necessary to identify effective treatment strategies. Currently, the treatment of spine-related diseases includes conservative, surgical, and minimally invasive interventional therapies. However, these treatment methods have several drawbacks such as drug tolerance and dependence, adjacent spondylosis, secondary surgery, infection, nerve injury, dural rupture, nonunion, and pseudoarthrosis. Further, it is more challenging to promote the regeneration of the interstitial disc and restore its biomechanical properties. Therefore, clinicians urgently need to identify methods that can limit disease progression or cure diseases at the etiological level. Platelet-rich plasma (PRP), a platelet-rich form of plasma extracted from venous blood, is a blood-derived product. Alpha granules contain a large number of cytokines, such as platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), epidermal growth factor, platelet factor 4 (PF-4), insulin-like growth factor-1 (IGF-1), and transforming growth factor-β (TGF-β). These growth factors allow stem cell proliferation and angiogenesis, promote bone regeneration, improve the local microenvironment, and enhance tissue regeneration capacity and functional recovery. This review describes the application of PRP in the treatment of spine-related diseases and discusses the clinical application of PRP in spinal surgery.

Study of the method of spinal cord neuron culture in Sprague-Dawley rats

This study aimed to explore the method of culture of spinal cord neurons (SPNs) in vitro and to provide prerequisites for studying the molecular mechanism and pharmacological mechanism of spinal cord injury and repair. The spinal cord tissues of neonatal Sprague-Dawley rats were taken and digested by trypsin, followed by cytarabine (Ara-C) to inhibit the proliferation of heterogeneous cells, differential velocity adhesion, and natural growth in neuron-specific medium. Then, the morphology of SPNs was observed. Ara-C treatment inhibited the growth of heterogeneous cells and the growth of spinal neurons. Using the differential velocity adhesion method, it was found that the adhesion time of heterogeneous cells and SPNs was not significantly different, and it could not separate neurons and heterogeneous cells well. A large number of mixed cells gathered and floated, and died on the 18th day. Compared with the 20th day, the cell viability of the 18th day was better (p < 0.001). The natural growth and culture of SPNs in Neurobasal-A medium can yield neurons of higher purity and SPNs from the 12th day to the 18th day can be selected for related in vitro cell experiments.

Neurogenesis potential of oligodendrocyte precursor cells from oligospheres and injured spinal cord

Severe traumatic spinal cord injury (SCI) leads to long-lasting oligodendrocyte death and extensive demyelination in the lesion area. Oligodendrocyte progenitor cells (OPCs) are the reservoir of new mature oligodendrocytes during damaged myelin regeneration, which also have latent potential for neurogenic regeneration and oligospheres formation. Whether oligospheres derived OPCs can differentiate into neurons and the neurogenesis potential of OPCs after SCI remains unclear. In this study, primary OPCs cultures were used to generate oligospheres and detect the differentiation and neurogenesis potential of oligospheres. In vivo, SCI models of juvenile and adult mice were constructed. Combining the single-cell RNA sequencing (scRNA-seq), bulk RNA sequencing (RNA-seq), bioinformatics analysis, immunofluorescence staining, and molecular experiment, we investigated the neurogenesis potential and mechanisms of OPCs in vitro and vivo. We found that OPCs differentiation and oligodendrocyte morphology were significantly different between brain and spinal cord. Intriguingly, we identify a previously undescribed findings that OPCs were involved in oligospheres formation which could further differentiate into neuron-like cells. We also firstly detected the intermediate states of oligodendrocytes and neurons during oligospheres differentiation. Furthermore, we found that OPCs were significantly activated after SCI. Combining scRNA-seq and bulk RNA-seq data from injured spinal cord, we confirmed the neurogenesis potential of OPCs and the activation of endoplasmic reticulum stress after SCI. Inhibition of endoplasmic reticulum stress could effectively attenuate OPCs death. Additionally, we also found that endoplasmic reticulum may regulate the stemness and differentiation of oligospheres. These findings revealed the neurogenesis potential of OPCs from oligospheres and injured spinal cord, which may provide a new source and a potential target for spinal cord repair.

Nrf2 Activation: Involvement in Central Nervous System Traumatic Injuries. A Promising Therapeutic Target of Natural Compounds

Central nervous system (CNS) trauma, such as traumatic brain injury (TBI) and spinal cord injury (SCI), represents an increasingly important health burden in view of the preventability of most injuries and the complex and expensive medical care that they necessitate. These injuries are characterized by different signs of neurodegeneration, such as oxidative stress, mitochondrial dysfunction, and neuronal apoptosis. Cumulative evidence suggests that the transcriptional factor nuclear factor erythroid 2-related factor 2 (Nrf2) plays a crucial defensive role in regulating the antioxidant response. It has been demonstrated that several natural compounds are able to activate Nrf2, mediating its antioxidant response. Some of these compounds have been tested in experimental models of SCI and TBI, showing different neuroprotective properties. In this review, an overview of the preclinical studies that highlight the positive effects of natural bioactive compounds in SCI and TBI experimental models through the activation of the Nrf2 pathway has been provided. Interestingly, several natural compounds can activate Nrf2 through multiple pathways, inducing a strong antioxidant response against CNS trauma. Therefore, some of these compounds could represent promising therapeutic strategies for these pathological conditions.

Acacetin alleviates neuroinflammation and oxidative stress injury via the Nrf2/HO-1 pathway in a mouse model of spinal cord injury

Spinal cord injury (SCI) is a severe central nervous system disease, which may cause serious locomotor deficit. Acacetin is a flavone that possesses antioxidant and anti-inflammatory effects in different human diseases. The main purpose of this study was to explore whether acacetin ameliorates SCI in mice. A model of SCI was established in C57BL/6 mice. The Basso Mouse Scale (BMS) score, BMS subscore, mechanical hypersensitivity, and thermal hypersensitivity of mice were tested for determining the motor function. Immunofluorescence staining was utilized to detect NeuN, GFAP, and Iba-1 levels in spinal cord tissues. ELISA was utilized to assess the contents of proinflammatory factors such as interleukin (IL)-1β, IL-18, and tumor necrosis factor-alpha (TNF-α) in spinal cord tissues. The levels of oxidative stress markers, reactive oxygen species, thiobarbituric acid-reactive substances, superoxide dismutase, catalase, glutathione peroxidase, and glutathione were detected using their corresponding kits. Western blot was employed for estimating the levels of heme oxygenase 1 (HO-1), nuclear factor E2-related factor 2 (Nrf2), and Kelch-like ECH-associated protein 1 (Keap-1). In this study, acacetin treatment recovered the motor function in SCI mice. Acacetin improved neuron integrity and repressed glial cell activation in the spinal cord tissues of SCI mice. Furthermore, acacetin administration reduced the SCI-induced high concentrations of IL-1β, IL-18, and TNF-α, as well as inhibited oxidative stress in SCI mice. Moreover, acacetin activated HO-1/Nrf2 pathway in SCI mice. The neuroprotective effects of acacetin against SCI were reversed by Nrf2 inhibitor. Overall, acacetin alleviated neuroinflammation and oxidative stress injury by activating the Nrf2/HO-1 signaling pathway in the mouse models of SCI.

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.

Molecular Characterization and Clinical Characteristics of m5C-Based RNA Methylation in Spinal Cord Injury: Validated by qPCR

Aberrant patterns of 5-methylcytosine (m5C)-based ribonucleic acid (RNA) methylation have critical roles in various human diseases, but their importance in spinal cord injury (SCI) is largely unknown. We explore the expression patterns and potential roles of m5C-based regulators of RNA modification after SCI. We analyzed 16 m5C-based regulators of RNA modification in tissues with SCI and normal rats from the Gene Expression Omnibus database. We constructed a "gene signature" of m5C-based regulators of RNA modification to predict the prognosis of SCI using least absolute shrinkage and selection operator regression and random-forest strategy. We found that the m5C-related genes, deoxyribonucleic acid (DNA) methyltransferase1 (Dnmt1), methyl-CpG binding domain protein 2 (Mbd2), ubiquitin-like with PHD and ring finger domains 1 (Uhrf1), uracil-N-glycosylase (Ung), and zinc finger and BTB(brica-brac, tramtrack, and broad) domain containing 38 (Zbtb38) had high expression, and zinc finger and BTB domain containing 4 (Zbtb4) had low expression in SCI. Analysis of the correlation between the gene sets of m5C-based regulators of RNA modification and immune-cell infiltration and immune response revealed Dnmt1, DNA methyltransferases 3A (Dnmt3a), Mbd2, and Ung to be positive regulators of the immune microenvironment, and Zbtb4 may negatively regulate the immune environment. Then, two molecular subtypes were identified based on 16 m5C-regulated genes. Functional-enrichment analysis of differentially expressed genes between different patterns of m5C-based modification was undertaken. Through the creation of a protein-protein interaction network, we screened 11 hub genes. We demonstrated their importance between SCI group and sham group using real-time reverse transcription-quantitative polymerase chain reaction in rat model. Expression of hub genes did not correlate with mitophagy but was positively correlated with endoplasmic reticulum stress (ERS), which suggested that there may be differences in ERS between different patterns of m5C-based modification. This present study explored and discovered the close link between m5C regulators-related genes and SCI. We also hope our findings may contribute to further mechanistic and therapeutic research on the role of key m5C regulators after SCI.

The Therapeutic and Prognostic Role of Clusterin in Diverse Musculoskeletal Diseases: A Mini Review

This mini-review aims to introduce the association between Secretory clusterin/apolipoprotein J (sCLU) and diverse musculoskeletal diseases. A comprehensive review of the literature was performed to identify basic science and clinical studies, which implied the therapeutic and prognostic role of sCLU in diverse musculoskeletal diseases. sCLU is a multifunctional glycoprotein that is ubiquitously expressed in various tissues and is implicated in many pathophysiological processes. Dysregulated expression of sCLU had been reported to be assocaited with proliferative or apoptotic molecular processes and inflammatory responses, which participated in many pathophysiological processes such as degenerative musculoskeletal diseases including ischemic osteonecrosis, osteoarthritis (OA) and degenerative cervical myelopathy (spinal cord injury), neoplastic musculoskeletal diseases, inflammatory and autoimmune musculoskeletal diseases including Rheumatoid arthritis (RA), joint damage induced by Brucella abortus, Sjogren's syndrome, idiopathic inflammatory myopathies, muscle glucose metabolism, insulin sensitivity and traumatic musculoskeletal diseases. Recent findings of sCLU in these musculoskeletal diseases provides insights on the therapeutic and prognostic role of sCLU in these musculoskeletal diseases. sCLU may serve as a promising therapeutic target for ischemic osteonecrosis, OA and spinal cord injury as well as a potential prognostic biomarker for OA and RA. Moreover, sCLU could act as a prognostic biomarker for osteosarcoma (OS) and a promising therapeutic target for OS resistance. Although many studies support the potential therapeutic and prognostic role of sCLU in some inflammatory and autoimmune-mediated musculoskeletal diseases, more future researches are needed to explore the molecular pathogenic mechanism mediated by sCLU implied in these musculoskeletal diseases.

Spinal Cord Injury Causes Marked Tissue Rearrangement in the Urethra-Experimental Study in the Rat

Traumatic spinal cord injury (SCI) results in the time-dependent development of urinary impairment due to neurogenic detrusor overactivity (NDO) and detrusor-sphincter-dyssynergia (DSD). This is known to be accompanied by massive changes in the bladder wall. It is presently less clear if the urethra wall also undergoes remodelling. To investigate this issue, female rats were submitted to complete spinal transection at the T8/T9 level and left to recover for 1 week and 4 weeks. To confirm the presence of SCI-induced NDO, bladder function was assessed by cystometry under urethane anesthesia before euthanasia. Spinal intact animals were used as controls. Urethras were collected and processed for further analysis. Following thoracic SCI, time-dependent changes in the urethra wall were observed. Histological assessment revealed marked urethral epithelium reorganization in response to SCI, as evidenced by an increase in epithelial thickness. At the muscular layer, SCI resulted in strong atrophy of the smooth muscle present in the urethral sphincter. Innervation was also affected, as evidenced by a pronounced decrease in the expression of markers of general innervation, particularly those present in sensory and sympathetic nerve fibres. The present data show an evident impact of SCI on the urethra, with significant histological rearrangement, accompanied by sensory and sympathetic denervation. It is likely that these changes will affect urethral function and contribute to SCI-induced urinary dysfunction, and they deserve further investigation.

Transplantation of olfactory ensheathing cells decreases local and serological monocyte chemoattractant protein 1 level during the acute phase of rat spinal cord injury

OBJECTIVES

Monocyte chemoattractant protein 1 (MCP1) is one of the most upregulated cytokines in the spinal cord and serum throughout acute spinal cord injury (SCI). Olfactory ensheathing cells (OECs) transplantation improves SCI through multiple mechanisms, including immunomodulation. Our study aimed to investigate whether OECs ameliorate acute inflammation after SCI by modulating MCP1 expression.

METHODS

We established a standardized clinically relevant contusion model using the NYU impactor. OECs were administered to the injured spinal cord via microinjection 30 minutes after injury. Rat locomotor functions were assessed by the Basso-Beattie-Bresnahan scale score. Time-course histopathological (H&E and IHC) analyses were performed to record rapid changes in acute inflammation at lesion epicenters. Serum MCP1 level was detected by ELISA assay.

RESULTS

BBB scores showed improved locomotor functional recoveries in the OECs transplantation group after SCI ( P < 0.05). Staining of H&E and CD68 illustrated that OECs transplantation attenuated inflammatory response by reducing lesion areas and infiltrating myeloid cell numbers. We further revealed significantly decreased MCP1 levels in the spinal cord and serum after OECs transplantation ( P < 0.05). Noteworthily, distinct expression levels of MCP1 were found in rats undergoing a mild injury (cord impacted from a 10-mm height) compared to the moderate injury (25-mm) group.

CONCLUSION

Our study reports that transplantation of OECs promotes locomotor functional recovery after SCI and alleviates acute inflammation by decreasing local and serological MCP1 levels. We provide preliminary evidence that MCP1 might serve as a potential biomarker to reflect the severity of SCI, which is of great interest in future studies.

Neural Stem Cells Overexpressing Arginine Decarboxylase Improve Functional Recovery from Spinal Cord Injury in a Mouse Model

Current therapeutic strategies for spinal cord injury (SCI) cannot fully facilitate neural regeneration or improve function. Arginine decarboxylase (ADC) synthesizes agmatine, an endogenous primary amine with neuroprotective effects. Transfection of human ADC (hADC) gene exerts protective effects after injury in murine brain-derived neural precursor cells (mNPCs). Following from these findings, we investigated the effects of hADC-mNPC transplantation in SCI model mice. Mice with experimentally damaged spinal cords were divided into three groups, separately transplanted with fluorescently labeled (1) control mNPCs, (2) retroviral vector (pLXSN)-infected mNPCs (pLXSN-mNPCs), and (3) hADC-mNPCs. Behavioral comparisons between groups were conducted weekly up to 6 weeks after SCI, and urine volume was measured up to 2 weeks after SCI. A subset of animals was euthanized each week after cell transplantation for molecular and histological analyses. The transplantation groups experienced significantly improved behavioral function, with the best recovery occurring in hADC-mNPC mice. Transplanting hADC-mNPCs improved neurological outcomes, induced oligodendrocyte differentiation and remyelination, increased neural lineage differentiation, and decreased glial scar formation. Moreover, locomotor and bladder function were both rehabilitated. These beneficial effects are likely related to differential BMP-2/4/7 expression in neuronal cells, providing an empirical basis for gene therapy as a curative SCI treatment option.

S100A1 expression is increased in spinal cord injury and promotes inflammation, oxidative stress and apoptosis of PC12 cells induced by LPS via ERK signaling

Spinal cord injury (SCI) is a severe neurological disorder and the molecular mechanisms leading to its poor prognosis remain to be elucidated. S100A1, a mediator of Ca2+ handling of sarcoplasmic reticulum and mitochondrial function, operates as an endogenous danger signal (alarmin) associated with inflammatory response and tissue injury. The aim of the present study was to investigate the expression and biological effects of S100A1 in SCI. A rat model of SCI and a PC12 cell model of lipopolysaccharide (LPS)‑induced inflammation were established to examine S100A1 expression at the mRNA and protein levels. The inflammation level, which was mediated by S100A1, was determined based on inflammatory factor (IL‑1β, IL‑6 and TNF‑α) and anti‑inflammatory factor (IL‑10) expression. The effects of S100A1 on cellular oxidation and anti‑oxidation levels were observed by detecting the levels of reactive oxygen species, superoxide dismutase, catalase activities and nuclear factor erythroid 2‑related factor 2 expression. The protein levels of Bax, Bcl2 and cleaved caspase‑3 were used for the evaluation of the effects of S100A1 on apoptosis. Phosphorylated (p‑)ERK1/2 expression was used to evaluate the effects of S100A1 on ERK signaling. The results revealed that S100A1 expression was significantly upregulated in vivo and in vitro in the PC12 cell model of LPS‑inflammation. The silencing and overexpression of S100A1 helped alleviate and aggravate LPS‑induced inflammation, oxidative stress and apoptosis levels, respectively. S100A1 was found to regulate the ERK signaling pathway positively. An inhibitor of ERK signaling (MK‑8353) partially abolished the promoting effects of the overexpression of S100A1 on inflammation, oxidative stress damage and apoptosis. In conclusion, S100A1 expression was elevated in model of SCI and in the PC12 cell model of LPS‑induced inflammation. Furthermore, the overexpression/silencing S100A1 aggravated/mitigated the inflammation, oxidative stress damage and the apoptosis of LPS‑stimulated PC12 cells via the ERK signaling pathway. The present study revealed the mechanism of S100A1 in SCI, which provided a new theoretic reference for future research on SCI.

Effects of Spinal Cord Injury Site on Cardiac Autonomic Regulation: Insight from Analysis of Cardiovascular Beat by Beat Variability during Sleep and Orthostatic Challenge

The goal of this study on Spinal Cord Injury (SCI) patients with cervical or thoracic lesion was to assess whether disturbances of ANS control, according to location, might differently affect vagal and sympatho-vagal markers during sleep and orthostatic challenge. We analyzed with linear and nonlinear techniques beat-by-beat RR and arterial pressure (and respiration) variability signals, extracted from a polysomnographic study and a rest-tilt test. We considered spontaneous or induced sympathetic excitation, as obtained shifting from non-REM to REM sleep or from rest to passive tilt. We obtained evidence of ANS cardiac (dys)regulation, of greater importance for gradually proximal location (i.e., cervical) SCI, compatible with a progressive loss of modulatory role of sympathetic afferents to the spinal cord. Furthermore, in accordance with the dual, vagal and sympathetic bidirectional innervation, the results suggest that vagally mediated negative feedback baroreflexes were substantially maintained in all cases. Conversely, the LF and HF balance (expressed specifically by normalized units) appeared to be negatively affected by SCI, particularly in the case of cervical lesion (group p = 0.006, interaction p = 0.011). Multivariate analysis of cardiovascular variability may be a convenient technique to assess autonomic responsiveness and alteration of functionality in patients with SCI addressing selectively vagal or sympathetic alterations and injury location. This contention requires confirmatory studies with a larger population.

Protocol paper: kainic acid excitotoxicity-induced spinal cord injury paraplegia in Sprague-Dawley rats

BACKGROUND

Excitotoxicity-induced in vivo injury models are vital to reflect the pathophysiological features of acute spinal cord injury (SCI) in humans. The duration and concentration of chemical treatment controls the extent of neuronal cell damage. The extent of injury is explained in relation to locomotor and behavioural activity. Several SCI in vivo methods have been reported and studied extensively, particularly contusion, compression, and transection models. These models depict similar pathophysiology to that in humans but are extremely expensive (contusion) and require expertise (compression). Chemical excitotoxicity-induced SCI models are simple and easy while producing similar clinical manifestations. The kainic acid (KA) excitotoxicity model is a convenient, low-cost, and highly reproducible animal model of SCI in the laboratory. The basic impactor approximately cost between 10,000 and 20,000 USD, while the kainic acid only cost between 300 and 500 USD, which is quite cheap as compared to traditional SCI method.

METHODS

In this study, 0.05 mM KA was administered at dose of 10 µL/100 g body weight, at a rate of 10 µL/min, to induce spinal injury by intra-spinal injection between the T12 and T13 thoracic vertebrae. In this protocol, detailed description of a dorsal laminectomy was explained to expose the spinal cord, following intra-spinal kainic acid administration at desired location. The dose, rate and technique to administer kainic acid were explained extensively to reflect a successful paraplegia and spinal cord injury in rats. The postoperative care and complication post injury of paraplegic laboratory animals were also explained, and necessary requirements to overcome these complications were also described to help researcher.

RESULTS

This injury model produced impaired hind limb locomotor function with mild seizure. Hence this protocol will help researchers to induce spinal cord injury in laboratories at extremely low cost and also will help to determine the necessary supplies, methods for producing SCI in rats and treatments designed to mitigate post-injury impairment.

CONCLUSIONS

Kainic acid intra-spinal injection at the concentration of 0.05 mM, and rate 10 µL/min, is an effective method create spinal injury in rats, however more potent concentrations of kainic acid need to be studied in order to create severe spinal injuries.

Secondary damage management of acute traumatic spinal cord injury in low and middle-income countries: A survey on a global scale (Part III)

•In LMICs, several factor may affect the applicability of guidelines for secondary damage control of spinal cord injury.•In LMICs, the use of steroids for spinal cord injury is heterogeneous and admissions to an intensive care units are limited.•The delays for surgical decompression of spinal cord injury can be significan and vary across income and geographic region.•Transfer times seem to be the most common reason for surgical delay in all income and geographic regions.•Costs for surgery for spinal trauma may be a significant barrier to guideline adherence, especially in low-resource settings.

Identification of beneficial Lebanese Trichoderma spp. wheat endophytes

Wheat is one of the most important crops in the world. Its production can be influenced by a diversity of beneficial and pathogenic rhizospheric microbes, including fungi. Amongst them, beneficial Trichoderma spp. can be used as alternatives to chemical fertilizers, as they are cheap and harmless to the environment. Our study aimed to isolate, identify, and characterize Trichoderma spp. from Lebanon associated with wheat. Two Trichoderma strains belonging to T. afroharzianum, and T. guizhouense species, were isolated and found to be endophytes, enhancing root growth and producing Indole-3-acetic acid. Inoculation also improved seedling development, and increased plant growth and yield. Furthermore, the two strains inhibit Fusarium growth in vitro. These Trichoderma spp. have thus the capacity to be used as organic fertilizers for wheat.

A tannic acid doped hydrogel with small extracellular vesicles derived from mesenchymal stem cells promotes spinal cord repair by regulating reactive oxygen species microenvironment

Spinal cord injury (SCI) is a serious disease of the central nervous system that is associated with a poor prognosis; furthermore, existing clinical treatments cannot restore nerve function in an effective manner. Inflammatory responses and the increased production of reactive oxygen species (ROS) in the microenvironment of the lesion are major obstacles that inhibit the recovery of SCI. Small extracellular vesicles (sEVs), derived from mesenchymal stem cells, are suitable options for cell-free therapy and have been shown to exert therapeutic effects in SCI, thus providing a potential strategy for microenvironment regulation. However, the effective retention, controlled release, and integration of small extracellular vesicles into injured spinal cord tissue are still a major challenge. Herein, we fabricated an N-acryloyl glycinamide/gelatin methacrylate/Laponite/Tannic acid (NAGA/GelMA/LPN/TA, NGL/T) hydrogel with sustainable sEV release (sEVs-NGL/T) to promote the recovery of motor function after SCI. The newly developed functional sEVs-NGL/T hydrogel exhibited excellent antioxidant properties in an H₂O₂-simulated peroxidative microenvironment in vitro. Implantation of the functional sEVs-NGL/T hydrogel in vivo could encapsulate sEVs, exhibiting efficient retention and the sustained release of sEVs, thereby synergistically inducing significant restoration of motor function and urinary tissue preservation. These positive effects can be attributed to the effective mitigation of the inflammatory and ROS microenvironment. Therefore, sEVs-NGL/T therapy provides a promising strategy for the sEV-based therapy in the treatment of SCI by comprehensively regulating the pathological microenvironment.

Human stem cell-derived neurons and neural circuitry therapeutics: Next frontier in spinal cord injury repair

Spinal cord injury (SCI) remains a life-altering event that devastates those injured and the families that support them. Numerous laboratories are engaged in preclinical and clinical trials to repair the injured spinal cord with stem cell-derived therapeutics. A new developmental paradigm reveals early bifurcation of brain or trunk neurons in mammals via neuromesodermal progenitors (NMPs) relevant to therapies requiring homotypic spinal cord neural populations. Human-induced pluripotent stem cell (hiPSC) NMP-derived spinal motor neurons generated ex vivo following this natural developmental route demonstrate robust survival in vivo when delivered as suspension grafts or as in vitro preformed encapsulated neuronal circuitry when transplanted into a rat C4-C5 hemicontusion injury site. Use of in vitro matured neurons avoids in vivo differentiation challenges of using pluripotent hiPSC or multipotent neural stem cell (NSC) or mesenchymal stem cell therapeutics. In this review, we provide an injury to therapeutics overview focusing on how stem cell and developmental fields are merging to generate exquisitely matched spinal motor neurons for SCI therapeutic studies. The complexity of the SCI microenvironment generated by trauma to neurons and vasculature, along with infiltrating inflammatory cells and scarring, underlies the challenging cytokine microenvironment that therapeutic cells encounter. An overview of evolving but limited stem cell-based SCI therapies that have progressed from preclinical to clinical trials illustrates the challenges and need for additional stem cell-based therapeutic approaches. The focus here on neurons describes how NMP-based neurotechnologies are advancing parallel strategies such as transplantation of preformed neuronal circuitry as well as human in vitro gastruloid multicellular models of trunk central and peripheral nervous system integration with organs. NMP-derived neurons are expected to be powerful drivers of the next generation of SCI therapeutics and integrate well with combination therapies that may utilize alternate biomimetic scaffolds for bridging injuries or flexible biodegradable electronics for electrostimulation.

Novel therapeutic approach to slow down the inflammatory cascade in acute/subacute spinal cord injury: Early immune therapy with lipopolysaccharide enhanced neuroprotective effect of combinational therapy of granulocyte colony-stimulating factor and bone-marrow mesenchymal stem cell in spinal cord injury

Bone-marrow mesenchymal stem cells (BM-MSCs) have not yet proven any significant therapeutic efficacy in spinal cord injury (SCI) clinical trials, due to the hostile microenvironment of the injured spinal cord at the acute phase. This study aims to modulate the inflammatory milieu by lipopolysaccharide (LPS) and granulocyte colony-stimulating factor (G-CSF) to improve the BM-MSCs therapy. For this purpose, we determined the optimum injection time and sub-toxic dosage of LPS following a T10 contusion injury. Medium-dose LPS administration may result in a local anti-inflammatory beneficial role. This regulatory role is associated with an increase in NF-200-positive cells, significant tissue sparing, and improvement in functional recovery compared to the SCI control group. The second aim was to examine the potential ability of LPS and LPS + G-CSF combination therapy to modulate the lesion site before BM-MSC (1 × 105 cells) intra-spinal injection. Our results demonstrated combination therapy increased potency to enhance the anti-inflammatory response (IL-10 and Arg-1) and decrease inflammatory markers (TNF-α and CD86) and caspase-3 compared to BM-MSC monotherapy. Histological analysis revealed that combination groups displayed better structural remodeling than BM-MSC monotherapy. In addition, Basso-Beattie-Bresnahan (BBB) scores show an increase in motor recovery in all treatment groups. Moreover, drug therapy shows faster recovery than BM-MSC monotherapy. Our results suggest that a sub-toxic dose of LPS provides neuroprotection to SCI and can promote the beneficial effect of BM-MSC in SCI. These findings suggest that a combination of LPS or LPS + G-CSF prior BM-MSC transplantation is a promising approach for optimizing BM-MSC-based strategies to treat SCI. However, because of the lack of some methodological limitations to examine the survival rate and ultimate fate of transplanted BM-MSCs followed by LPS administration in this study, further research needs to be done in this area. The presence of only one-time point for evaluating the inflammatory response (1 week) after SCI can be considered as one of the limitations of this study. We believed that the inclusion of additional time points would provide more information about the effect of our combination therapy on the microglia/macrophage polarization dynamic at the injured spinal cord.

Integrated transcriptomic and metabolomic profiling reveals dysregulation of purine metabolism during the acute phase of spinal cord injury in rats

Introduction

Spinal cord injury (SCI) results in drastic dysregulation of microenvironmental metabolism during the acute phase, which greatly affects neural recovery. A better insight into the potential molecular pathways of metabolic dysregulation by multi-omics analysis could help to reveal targets that promote nerve repair and regeneration in the future.

Materials and methods

We established the SCI model and rats were randomly divided into two groups: the acute-phase SCI (ASCI) group (n = 14, 3 days post-SCI) and the sham group with day-matched periods (n = 14, without SCI). In each group, rats were sacrificed at 3 days post-surgery for histology study (n = 3), metabolome sequencing (n = 5), transcriptome sequencing (n = 3), and quantitative real-time polymerase chain reaction (n = 3). The motor function of rats was evaluated by double-blind Basso, Beattie, and Bresnahan (BBB) Locomotor Scores at 0, 1, 2, 3 days post-SCI in an open field area. Then the transcriptomic and metabolomic data were integrated in SCI model of rat to reveal the underlying molecular pathways of microenvironmental metabolic dysregulation.

Results

The histology of the microenvironment was significantly altered in ASCI and the locomotor function was significantly reduced in rats. Metabolomics analysis showed that 360 metabolites were highly altered during the acute phase of SCI, of which 310 were up-regulated and 50 were down-regulated, and bioinformatics analysis revealed that these differential metabolites were mainly enriched in arginine and proline metabolism, D-glutamine and D-glutamate metabolism, purine metabolism, biosynthesis of unsaturated fatty acids. Transcriptomics results showed that 5,963 genes were clearly altered, of which 2,848 genes were up-regulated and 3,115 genes were down-regulated, and these differentially expressed genes were mainly involved in response to stimulus, metabolic process, immune system process. Surprisingly, the Integrative analysis revealed significant dysregulation of purine metabolism at both transcriptome and metabolome levels in the acute phase of SCI, with 48 differential genes and 16 differential metabolites involved. Further analysis indicated that dysregulation of purine metabolism could seriously affect the energy metabolism of the injured microenvironment and increase oxidative stress as well as other responses detrimental to nerve repair and regeneration.

Discussion

On the whole, we have for the first time combined transcriptomics and metabolomics to systematically analyze the potential molecular pathways of metabolic dysregulation in the acute phase of SCI, which will contribute to broaden our understanding of the sophisticated molecular mechanisms of SCI, in parallel with serving as a foundation for future studies of neural repair and regeneration after SCI.

Quercetin Derivatives in Combating Spinal Cord Injury: A Mechanistic and Systematic Review

Spinal cord injury (SCI) possesses a complicated etiology. There is no FDA-approved treatment for SCI, and the majority of current interventions focus on reducing symptoms. During SCI, inflammation, oxidative stress, apoptosis, and autophagy are behind the secondary phase of SCI and cause serious consequences. It urges the need for providing multi-targeting agents, that possess lower side effects and higher efficacy. The plant secondary metabolites are multi-targeting agents and seem to provide new roads in combating diseases. Flavonoids are phytochemicals of continual interest to scientists in combating neurodegenerative diseases (NDDs). Flavonoids are being studied for their biological and pharmacological effects, particularly as antioxidants, anti-inflammatory agents, anti-apoptotic, and autophagy regulators. Quercetin is one of the most well-known flavonols known for its preventative and therapeutic properties. It is a naturally occurring bioactive flavonoid that has recently received a lot of attention for its beneficial effects on NDDs. Several preclinical evidence demonstrated its neuroprotective effects. In this systematic review, we aimed at providing the biological activities of quercetin and related derivatives against SCI. Detailed neuroprotective mechanisms of quercetin derivatives are also highlighted in combating SCI.

Macrophage Extracellular Traps Exacerbate Secondary Spinal Cord Injury by Modulating Macrophage/Microglia Polarization via LL37/P2X7R/NF-κB Signaling Pathway

Persistent inflammation in the secondary spinal cord injury (SCI) is an important reason for the failure of nerve repair, which is partly due to the continuous activation of local M1-like macrophage/microglia. It is reported that extracellular trap (ET) has been a new way of cell death, which can be released by macrophages and named macrophage extracellular trap (Met). Furthermore, it exists widely in the pathophysiological process of many diseases, but it has been rarely studied in the field of SCI. In this study, we constructed a spinal cord contusion model and assessed the function outcome of SCI rats. We used immunofluorescence, flow cytometry, and transmission electron microscope (TEM) to demonstrate the existence of Mets. Besides, some related experiments had also been employed to explore the relationship between Mets and M1 polarization of macrophage/microglia. We also performed Co-IP and Western blotting to reveal a new extracellular proinflammatory signal pathway. Finally, we made a linear regression analysis between the concentrations of specific markers of Mets in human serum and ASIA scores. Briefly, our results suggested that macrophages infiltrated in SCI area could induce macrophage/microglia to differentiate into M1-like cells by releasing Mets, which may be achieved partly through LL37-P2X37-NF-κB signal pathway. However, limiting Mets could effectively inhibit M1 polarization and promote function recovery. In addition, the concentrations of Met related proteins in human serum showed high correlation with ASIA scores and could be applied to reflect the severity of SCI. In conclusion, Mets may be a new target for SCI therapy and a promising index for SCI assessment.

Application and prospects of somatic cell reprogramming technology for spinal cord injury treatment

Spinal cord injury (SCI) is a serious neurological trauma that is challenging to treat. After SCI, many neurons in the injured area die due to necrosis or apoptosis, and astrocytes, oligodendrocytes, microglia and other non-neuronal cells become dysfunctional, hindering the repair of the injured spinal cord. Corrective surgery and biological, physical and pharmacological therapies are commonly used treatment modalities for SCI; however, no current therapeutic strategies can achieve complete recovery. Somatic cell reprogramming is a promising technology that has gradually become a feasible therapeutic approach for repairing the injured spinal cord. This revolutionary technology can reprogram fibroblasts, astrocytes, NG2 cells and neural progenitor cells into neurons or oligodendrocytes for spinal cord repair. In this review, we provide an overview of the transcription factors, genes, microRNAs (miRNAs), small molecules and combinations of these factors that can mediate somatic cell reprogramming to repair the injured spinal cord. Although many challenges and questions related to this technique remain, we believe that the beneficial effect of somatic cell reprogramming provides new ideas for achieving functional recovery after SCI and a direction for the development of treatments for SCI.

Effects of melatonin-pretreated adipose-derived mesenchymal stem cells (MSC) in an animal model of spinal cord injury

Background

One of the most serious nervous system diseases is spinal cord injury(SCI), which is increasing for various reasons. Although no definitive treatment has yet been identified for SCI, one possible treatment is adipose-derived stem cells(ADSCs). However, a key issue in transplantation is improving cells’ survival and function in the target tissue. Melatonin(MT) hormone with antioxidant properties can prolong cell survival and improve cell function. This study investigates the pre-conditioning of ADSCs with melatonin for enhancing the engraftment and neurological function of rats undergoing SCI.

Methods

42 male Sprague–Dawley rats were divided into six groups, including Control, Sham, Model, Vehicle, and Lesion treatments A and B. After acquiring white adipose tissue, stem cells were evaluated by flow cytometry. SCI was then applied in Model, Vehicle, A, and B groups. Group A and B received ADSCs and ADSCs + melatonin, respectively, 1 week after SCI, but the vehicle received only an intravenous injection for simulation; The other groups were recruited for the behavioral test. Immunohistochemistry(IHC) was used to assess the engraftment and differentiation of ADSCs in the SCI site. Basso, Beattie, and Bresnahan's score was used to evaluate motor function between the six groups.

Results

Histological studies and cell count confirmed ADSCs implantation at the injury site, which was higher in the MT-ADSCs (P < 0.001). IHC revealed the differentiation of ADSCs and MT-ADSCs into neurons, astrocytes, and oligodendrocyte lineage cells, which were higher in MT-ADSCs. Functional improvement was observed in SCI + ADSCs and SCI + MT-ADSCs groups.

Conclusion

The pre-conditioning of ADSCs with melatonin positively affects engraftment and neuronal differentiation in SCI but does not impact performance improvement compared to the ADSCs.