Interactions of primary insult biomechanics and secondary cascades in spinal cord injury: implications for therapy

Features of Remyelination after Transplantation of Olfactory Ensheathing Cells with Neurotrophic Factors into Spinal Cord Cysts

This paper shows for the first time that co-transplantation of human olfactory ensheathing cells with neurotrophin-3 into spinal cord cysts is more effective for activation of remyelination than transplantation of cells with brain-derived neurotrophic factor and a combination of these two factors. The studied neurotrophic factors do not affect proliferation and migration of ensheathing cells in vitro. It can be concluded that the maximum improvement of motor function in rats receiving ensheathing cells with neurotrophin-3 is largely determined by activation of remyelination.

Rehabilitation training enhanced the therapeutic effect of calycosin on neurological function recovery of rats following spinal cord injury

BACKGROUND

Calycosin (CA), a flavonoids component, has demonstrated potential neuroprotection effects by inhibiting oxidative stress in spinal cord injury (SCI) models. This study aims to investigate the impact of combined rehabilitation training (RT) and calycosin therapy on neurological function following SCI, primarily by assessing changes in motor function recovery, neuronal survival, neuronal oxidative stress levels, and neural proliferation, in order to provide novel insights for the treatment of SCI.

MATERIALS AND METHODS

The SCI model was constructed by compressing the spinal cord using vascular clamps. Calycosin was injected intraperitoneally into the SCI model rats, and a group of 5 rats underwent RT. The motor function of rats after SCI was evaluated using the Basso Beattle Bresnaha (BBB) score and the inclined plate test. Histopathological changes were evaluated by NeuN immunohistochemistry, HE and Nissl staining. Apoptosis was detected by TUNEL staining. The antioxidant effect of combined treatment was assessed by measuring changes in oxidative stress markers after SCI. Western blot analysis was conducted to examine changes in Hsp90-Akt/ASK1-p38 pathway-related proteins. Finally, cell proliferation was detected by BrdU and Ki67 assays.

RESULTS

RT significantly improved the BBB score and angle of incline promoted by calycosin, resulting in enhanced motor function recovery in rats with SCI. Combining rehabilitation training with calycosin has a positive effect on morphological recovery. Similarly, combined RT enhanced the Nissl and NeuN staining signals of spinal cord neurons increased by calycosin, thereby increasing the number of neurons. TUNEL staining results indicated that calycosin treatment reduced the apoptosis signal in SCI, and the addition of RT further reduced the apoptosis. Moreover, RT combined with calycosin reduced oxidative stress by increasing SOD and GSH levels, while decreasing MDA, NO, ROS, and LDH expressions compared to the calycosin alone. RT slightly enhanced the effect of calycosin in activating Hsp90 and Akt and inhibiting the activation of ASK1 and p38, leading to enhanced inhibition of oxidative stress by calycosin. Additionally, the proliferation indexes (Ki67 and BrdU) assays showed that calycosin treatment alone increased both, whereas the combination treatment further promoted cell proliferation.

CONCLUSION

Our research findings demonstrate that rehabilitation training enhances the ability of calycosin to reduce oxidative stress, resulting in a decrease in neuronal apoptosis and an increase in proliferation, ultimately promoting neuronal survival.

Network pharmacology integrated with experimental validation to explore the therapeutic role and potential mechanism of Epimedium for spinal cord injury

Objective

Epimedium (EPI) is a common Chinese herb with neuroprotective effects against a variety of central nervous system disorders, especially spinal cord injury (SCI). In this study, we performed network pharmacology and molecular docking analyses to reveal the mechanism underlying EPI treatment of SCI, then validated its efficacy using animal models.

Methods

The active ingredients and targets of EPI were screened by Traditional Chinese Medicine Systems Pharmacology (TCMSP) and their targets annotated on the UniProt platform. SCI-related targets were searched from OMIM, TTD, and GeneCards databases. We employed the STRING platform to construct a protein-protein interaction (PPI) network then visualized the results using Cytoscape (3.8.2) software. We also subjected key EPI targets to ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, then docked the main active ingredients with the key targets. Finally, we established an SCI rat model to evaluate efficacy of EPI in treating SCI and validate the effects of different biofunctional modules predicted by network pharmacology.

Results

A total of 133 EPI targets were associated with SCI. GO terms and KEGG pathway enrichment results showed that EPI's effect in treating SCI was significantly associated with inflammatory response, oxidative stress and the PI3K/AKT signaling pathway. Molecular docking results indicated that EPI's active ingredients have a high affinity for the key targets. Results from animal experiments revealed that EPI not only markedly improved Basso, Beattie, and Bresnahan scores in SCI rats, but also significantly improved p-PI3K/PI3K and p-AKT/AKT ratio. Moreover, EPI treatment not only mediated a significant decrease in malondialdehyde (MDA) but also increased both superoxide dismutase (SOD), and glutathione (GSH). However, this phenomenon was successfully reversed by LY294002, a PI3K inhibitor.

Conclusion

EPI improves behavioral performance in SCI rats through anti-oxidative stress, which may be mediated by activation of the PI3K/AKT signaling pathway.

Sitagliptin attenuates neuronal apoptosis via inhibiting the endoplasmic reticulum stress after acute spinal cord injury

Regulation of endoplasmic reticulum stress (ER) stress-induced apoptosis and nerve regeneration is a hopeful way for acute spinal cord injury (SCI). Sitagliptin (Sita) is one of dipeptidyl peptidase-4 (DPP-4) inhibitor, which is beneficial neurons damaged diseases. However, its protective mechanisms of avoiding nerve injury remain unclear. In this study, we further investigated the mechanism of the anti-apoptotic and neuroprotective effects of Sita in promoting locomotor recovery from SCI. In vivo results showed that Sita treatment reduced neural apoptosis caused by SCI. Moreover, Sita effectively attenuated the ER tress and associated apoptosis in rats with SCI. A striking feature was the occurrence of nerve fiber regeneration at the lesion site, which eventually led to significant locomotion recovery. In vitro results showed that the PC12 cell injury model induced by Thapsigargin (TG) also showed similar neuroprotective effects. Overall, sitagliptin showed potent neuroprotective effects by targeting the ER stress-induced apoptosis both in vivo and vitro, thus facilitating the regeneration of the injured spinal cord.

Notoginsenoside R1 alleviates spinal cord injury by inhibiting oxidative stress, neuronal apoptosis, and inflammation via activating the nuclear factor erythroid 2 related factor 2/heme oxygenase-1 signaling pathway

The secondary injury plays a vital role in the development of spinal cord injury (SCI), which is characterized by the occurrence of oxidative stress, neuronal apoptosis, and inflammatory response. Notoginsenoside R1 (NGR1) has been involved in the modulation of antioxidative stress and anti-inflammatory response. However, its roles in SCI-induced injury are still unknown. We explored the therapeutic effect of NGR1 and its underlying mechanism after SCI by using behavioral, biochemical, and immunohistochemical techniques. The administration of NGR1 after SCI enhanced the neurological function, and mitigated tissue damage and motor neuron loss than those in SCI + vehicle group. Meanwhile, significantly increased expression of Nrf2 protein and HO-1 protein was found in the SCI + NGR1 group compared with those in the SCI + vehicle group. In addition, the inhibitory effects of oxidative stress, apoptotic neuron ratio, and neuronal inflammation in the SCI + NGR1 group can be partially reversed when the Nrf2/HO-1 signaling pathway was inhibited by ML385. Our results indicate that the administration of NGR1 can attenuate oxidative stress, neuronal apoptosis, and inflammation by activating the Nrf2/HO-1 signaling pathway after SCI, thereby improving neurological function.

Traumatic Nervous System Injury

Mechanisms of traumatic nervous system injury to a degree are similar, but differences exist in etiology, pathophysiology, and treatment of brain, spinal cord, and peripheral nerve injury. The most common clinical abnormalities seen in the horse are abnormal level of consciousness, abnormal behavior, seizures, cranial nerve deficits, vestibular disease, tetra- and paraparesis or paraplegia, cauda equina syndrome, specific gait deficits, and muscle atrophy. Treatments are directed toward reducing inflammation and swelling, halting secondary injury, and promoting mechanisms of neuroregeneration and plasticity. Prognosis depends on the severity of primary injury and the neuroanatomic location and extent of nervous tissue damage.

3D Bioprinting for Spinal Cord Injury Repair

Spinal cord injury (SCI) is considered to be one of the most challenging central nervous system injuries. The poor regeneration of nerve cells and the formation of scar tissue after injury make it difficult to recover the function of the nervous system. With the development of tissue engineering, three-dimensional (3D) bioprinting has attracted extensive attention because it can accurately print complex structures. At the same time, the technology of blending and printing cells and related cytokines has gradually been matured. Using this technology, complex biological scaffolds with accurate cell localization can be manufactured. Therefore, this technology has a certain potential in the repair of the nervous system, especially the spinal cord. So far, this review focuses on the progress of tissue engineering of the spinal cord, landmark 3D bioprinting methods, and landmark 3D bioprinting applications of the spinal cord in recent years.

Trauma Indicators in Spinal Cord Injury Rehabilitation Outcomes: A Retrospective Cohort Analysis of the National Trauma Data Bank and National Spinal Cord Injury Database

OBJECTIVE

To investigate whether initial emergency room physiologic measures and metrics of trauma severity predict functional outcomes and neurologic recovery in traumatic spinal cord injury.

DESIGN

Retrospective analysis of a clinical database.

SETTING

Merged multi-center data from the Spinal Cord Injury Model Systems (SCIMS) database and National Trauma Data Bank (NTDB) from six academic medical centers across the United States.

PARTICIPANTS

319 patients admitted to SCIMS rehabilitation centers within one-year of injury. The majority of patients were male (76.2%), with a mean age of 44 (SD 19). At rehabilitation admission, the most common neurologic level of injury was low cervical (C5-C8, 39.5%) and ASIA impairment scale (AIS) was A (34.4%).

MAIN OUTCOME MEASURES(S)

Primary outcomes were (1) Functional Independence Measure (FIM) motor score at discharge from inpatient rehabilitation and (2) change in FIM motor score between inpatient rehabilitation admission and discharge. We hypothesized that derangements in emergency room physiologic measures, such as decreased blood pressure and oxygen saturation, as well as increased severity of trauma burden, would predict poorer functional outcomes.

RESULTS

Linear regression analysis showed that neurologic level of injury and AIS predicted discharge FIM motor score. Systolic blood pressure, heart rate, oxygen saturation, need for assisted respiration, and presence of penetrating injury did not predict discharge motor FIM or FIM motor score improvement.

CONCLUSIONS

Initial emergency room physiologic parameters did not prognosticate functional outcomes in this cohort.

Unlike Brief Inhibition of Microglia Proliferation after Spinal Cord Injury, Long-Term Treatment Does Not Improve Motor Recovery

Microglia are major players in scar formation after an injury to the spinal cord. Microglia proliferation, differentiation, and survival are regulated by the colony-stimulating factor 1 (CSF1). Complete microglia elimination using CSF1 receptor (CSF1R) inhibitors worsens motor function recovery after spinal injury (SCI). Conversely, a 1-week oral treatment with GW2580, a CSF1R inhibitor that only inhibits microglia proliferation, promotes motor recovery. Here, we investigate whether prolonged GW2580 treatment further increases beneficial effects on locomotion after SCI. We thus assessed the effect of a 6-week GW2580 oral treatment after lateral hemisection of the spinal cord on functional recovery and its outcome on tissue and cellular responses in adult mice. Long-term depletion of microglia proliferation after SCI failed to improve motor recovery and had no effect on tissue reorganization, as revealed by ex vivo diffusion-weighted magnetic resonance imaging. Six weeks after SCI, GW2580 treatment decreased microglial reactivity and increased astrocytic reactivity. We thus demonstrate that increasing the duration of GW2580 treatment is not beneficial for motor recovery after SCI.

MicroRNA-488 inhibits neural inflammation and apoptosis in spinal cord injury through restraint on the HMGB1/TLR4/NF-κB signaling pathway

OBJECTIVES

Secondary spinal cord injury (SCI), a reversible pathological change, involves neural inflammation and apoptosis. This study explored how microRNA (miR)-488, an inflammatory regulator as reported affected secondary SCI.

METHODS

In vivo, Wistar rats were clipped on the spinal cord for SCI induction. In vitro, PC-12 cells were treated with lipopolysaccharide (LPS) to induce cell injuries to mimic the environment during the secondary SCI. Cell viability and apoptosis were measured by CCK-8 assay and flow cytometry. The levels of inflammation-related factors (interleukin (IL)-6, IL-1β and tumor necrosis factor (TNF)-α) in the serum and PC-12 cells were determined by ELISA. The expressions of miR-488, high mobility group box 1 (HMGB1), B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), cleaved caspase-3, toll-like receptor 4 (TLR4), phosphorylated (p)-p65 and total-p65 in rat spinal cord or PC-12 cells were analyzed by quantitative reverse transcription PCR or western blot.

RESULTS

After SCI induction, rats exhibited low Basso-Beattie-Bresnahan scores, promoted the release of inflammation-related factors and downregulated miR-488. LPS treatment decreased cell viability, enhanced apoptosis and downregulated miR-488. Upregulating miR-488 neutralized LPS-induced releases of inflammation-related factors and expressions of Bax and cleaved caspase-3 and counteracted LPS-induced inhibition on Bcl-2 expression. MiR-488 directly targeted HMGB1 and miR-488 mimic decreased LPS-induced HMGB1 expression. Overexpressing HMGB1 counteracted miR-488 mimic-induced decreases in the expressions of TLR4 and p-p65 and the ratio of p-p65 to Total-p65 in LPS-treated PC-12 cells.

CONCLUSION

MiR-488 inhibited neural inflammation and apoptosis in SCI via its binding with HMGB1-mediated restraint on the TLR4/NF-κB signaling pathway.

Early Trauma Indicators and Rehabilitation Outcomes in Traumatic Spinal Cord Injury

Objectives

To investigate the relationship between early trauma indicators and neurologic recovery after traumatic SCI using standardized outcome measures from the ISNCSCI examination and standardized functional outcome measures for rehabilitation populations.

Methods

This is a retrospective review of merged, prospectively collected, multicenter data from the Spinal Cord Injury Model Systems (SCIMS) database and institutional trauma databases from five academic medical centers across the United States. Functional status at inpatient rehabilitation discharge and change in severity and level of injury from initial SCI to inpatient rehabilitation discharge were analyzed to assess neurologic recovery for patients with traumatic SCI. Linear and logistic regression with multiple imputation were used for the analyses.

Results

A total of 209 patients were identified. Mean age at injury was 47.2 ± 18.9 years, 72.4% were male, 22.4% of patients had complete injuries at presentation to the emergency department (ED), and most patients were admitted with cervical SCI. Mean systolic blood pressure (SBP) was 124.1 ± 29.6 mm Hg, mean ED heart rate was 83.7 ± 19.9 bpm, mean O2 saturation was 96.8% ± 4.0%, and mean Glasgow Coma Scale (GCS) score was 13.3 ± 3.9. The average Injury Severity Score (ISS) in this population was 22.4. Linear regression analyses showed that rehabilitation discharge motor FIM was predicted by motor FIM on admission and ISS. Requiring ventilatory support on ED presentation was negatively associated with improvement of ASIA Impairment Scale (AIS) grade at rehabilitation discharge compared with AIS grade after initial injury. Emergency room physiologic measures (SBP, pulse, oxygen saturation) did not predict discharge motor FIM or improvement in AIS grade or neurological level of injury.

Conclusion

Our study showed a positive association between discharge FIM and ISS and a negative association between ventilatory support at ED presentation and AIS improvement. The absence of any significant association between other physiologic or clinical variables at ED presentation with rehabilitation outcomes suggests important areas for future clinical research.

Decoding epigenetic codes: new frontiers in exploring recovery from spinal cord injury

Spinal cord injury that results in severe neurological disability is often incurable. The poor clinical outcome of spinal cord injury is mainly caused by the failure to reconstruct the injured neural circuits. Several intrinsic and extrinsic determinants contribute to this inability to reconnect. Epigenetic regulation acts as the driving force for multiple pathological and physiological processes in the central nervous system by modulating the expression of certain critical genes. Recent studies have demonstrated that post-SCI alteration of epigenetic landmarks is strongly associated with axon regeneration, glial activation and neurogenesis. These findings not only establish a theoretical foundation for further exploration of spinal cord injury, but also provide new avenues for the clinical treatment of spinal cord injury. This review focuses on the epigenetic regulation in axon regeneration and secondary spinal cord injury. Together, these discoveries are a selection of epigenetic-based prognosis biomarkers and attractive therapeutic targets in the treatment of spinal cord injury.

RETRACTED: Tanshinone IIA alleviates oxidative damage after spinal cord injury in vitro and in vivo through up-regulating miR-124

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Corresponding Author with the agreement of the editor. The authors used DMSO (dimethyl sulfoxide) to dissolve tanshinone IIA in this experiment, but even after dilution, DMSO also can induce toxicity of PC12 cells, which also can affect the result of the experiment. After discussion, the authors found that sulfotanshinone sodium injection can be used to replace tanshinone II A, which is both an aqueous solution and has been clinically proved to be an ideal substitute. Further, in error, the authors used 0μM /12.5μM /50μM /100μM /200μM H2O2 to stimulate oxidative injury as in figure 1A, but missed 25μM H2O2, which may also affect the experimental results.

Spinal Cord Injuries in Dogs Part I: A Review of Basic Knowledge

Spinal cord injuries (SCI) in dogs are not frequent, but they are serious pathological conditions accompanied with high morbidity and mortality. The pathophysiology of SCI involves a primary insult, disrupting axons, blood vessels, and cell membranes by mechanical force, or causes tissue necrosis by ischemia and reperfusion. The primary injury is followed by a cascade of secondary events, involving vascular dysfunction, edema formation, continuing ischemia, excitotoxicity, electrolyte shifts, free radical production, inflammation, and delayed apoptotic cell death. The most frequent cause of SCI in dogs is an acute intervertebral disc extrusion, exogenous trauma or ischemia. Neurological symptomatology depends on the location, size and the type of spinal cord lesions. It is characterized by transient or permanent, incomplete or complete loss of motor, sensory, autonomic, and reflex functions caudal to the site of the lesion. In a case of partial spinal cord (SC) damage, one of the typical syndromes develops (e. g. Brown-Séquard syndrome, central SC syndrome, ventral SC syndrome, dorsal SC syndrome, conus medullaris syndrome, or traumatic cauda equina syndrome). The severe transversal spinal cord lesion in the cervical region causes paresis or plegia of all four extremities (tetraparesis, tetraplegia); in thoracic or lumbosacral region, paresis or plegia of the pelvic extremities (paraparesis, paraplegia), i. e. sensory-motor deficit, urinary and foecal incontinence and sexual incompetence. The central nervous system in mammals does not regenerate, so the neurological deficit in dogs following severe SCI persists for the rest of their lives and animals display an image of permanent suffering. The research strategy presented here involved a PubMed, Medline (Ovid) and ISI Web of Science literature search from Januray 2001 to December 2017 using the term “canine spinal cord injury” in the English language; also references from selected papers were scanned and relevant articles included.

Spinal Cord Injury Scarring and Inflammation: Therapies Targeting Glial and Inflammatory Responses

Deficits in neuronal function are a hallmark of spinal cord injury (SCI) and therapeutic efforts are often focused on central nervous system (CNS) axon regeneration. However, secondary injury responses by astrocytes, microglia, pericytes, endothelial cells, Schwann cells, fibroblasts, meningeal cells, and other glia not only potentiate SCI damage but also facilitate endogenous repair. Due to their profound impact on the progression of SCI, glial cells and modification of the glial scar are focuses of SCI therapeutic research. Within and around the glial scar, cells deposit extracellular matrix (ECM) proteins that affect axon growth such as chondroitin sulfate proteoglycans (CSPGs), laminin, collagen, and fibronectin. This dense deposition of material, i.e., the fibrotic scar, is another barrier to endogenous repair and is a target of SCI therapies. Infiltrating neutrophils and monocytes are recruited to the injury site through glial chemokine and cytokine release and subsequent upregulation of chemotactic cellular adhesion molecules and selectins on endothelial cells. These peripheral immune cells, along with endogenous microglia, drive a robust inflammatory response to injury with heterogeneous reparative and pathological properties and are targeted for therapeutic modification. Here, we review the role of glial and inflammatory cells after SCI and the therapeutic strategies that aim to replace, dampen, or alter their activity to modulate SCI scarring and inflammation and improve injury outcomes.