Rat models of spinal cord injury: from pathology to potential therapies

The anti-inflammatory and immunomodulatory effects of olfactory ensheathing cells transplantation in spinal cord injury and concomitant pathological pain

Spinal cord injury (SCI) is a serious and disabling injury that is often accompanied by neuropathic pain (NeP), which severely affects patients' motor and sensory functions and reduces their quality of life. Currently, there is no specific treatment for treating SCI and relieving the accompanying pain, and we can only rely on medication and physical rehabilitation, both of which are ineffective. Researchers have recently identified a novel class of glial cells, olfactory ensheathing cells (OECs), which originate from the olfactory system. Transplantation of OECs into damaged spinal cords has demonstrated their capacity to repair damaged nerves, improve the microenvironment at the point of injury, and They can also restore neural connectivity and alleviate the patient's NeP to a certain extent. Although the effectiveness of OECs transplantation has been confirmed in experiments, the specific mechanisms by which it repairs the spinal cord and relieves pain have not been articulated. Through a review of the literature, it has been established that the ability of OECs to repair and relieve pain is inextricably linked to its anti-inflammatory and immunomodulatory effects. In this regard, it is imperative to gain a deeper understanding of how OECs exert their anti-inflammatory and immunomodulatory effects. The objective of this paper is to provide a comprehensive overview of the mechanisms by which OECs exert anti-inflammatory and immunomodulatory effects. We aim to manipulate the immune microenvironment at the transplantation site through the intervention of cytokines and immune cells, with the goal of enhancing OECs' function or creating a conducive microenvironment for OECs' survival. This approach is expected to improve the therapeutic efficacy of OECs in clinical settings. However, numerous fundamental and clinical challenges remain to be addressed if OEC transplantation therapy is to become a standardized treatment in clinical practice.

Sovateltide (ILR-1620) Improves Motor Function and Reduces Hyperalgesia in a Rat Model of Spinal Cord Injury

BACKGROUND

Spinal cord injury (SCI) presents a major global health challenge, with rising incidence rates and substantial disability. Although progress has been made in understanding SCI's pathophysiology and early management, there is still a lack of effective treatments to mitigate long-term consequences. This study investigates the potential of sovateltide, a selective endothelin B receptor agonist, in improving clinical outcomes in an acute SCI rat model.

METHODS

Thirty male Sprague-Dawley rats underwent sham surgery (group A) or SCI and treated with vehicle (group B) or sovateltide (group C). Clinical tests, including Basso, Beattie, and Bresnahan scoring, inclined plane, and allodynia testing with von Frey hair, were performed at various time points. Statistical analyses assessed treatment effects.

RESULTS

Sovateltide administration significantly improved motor function, reducing neurological deficits and enhancing locomotor recovery compared with vehicle-treated rats, starting from day 7 post injury. Additionally, the allodynic threshold improved, suggesting antinociceptive properties. Notably, the sovateltide group demonstrated sustained recovery, and even reached preinjury performance levels, whereas the vehicle group plateaued.

CONCLUSIONS

This study suggests that sovateltide may offer neuroprotective effects, enhancing neurogenesis and angiogenesis. Furthermore, it may possess anti-inflammatory and antinociceptive properties. Future clinical trials are needed to validate these findings, but sovateltide shows promise as a potential therapeutic strategy to improve functional outcomes in SCI. Sovateltide, an endothelin B receptor agonist, exhibits neuroprotective properties, enhancing motor recovery and ameliorating hyperalgesia in a rat SCI model. These findings could pave the way for innovative pharmacological interventions for SCI in clinical settings.

LncRNA OIP5-AS1 regulates ferroptosis and mitochondrial dysfunction-mediated apoptosis in spinal cord injury by targeting the miR-128-3p/Nrf2 axis

Background

Ferroptosis is an important way of neuronal cell death in acute phase and participates in the inflammatory cascade after spinal cord injury (SCI). It is reported that microRNA (miRNA) and long non-coding RNA (lncRNA) are key mediators in the regulation of ferroptosis. This study will explore the inhibitory effect of LncRNA OIP5-AS1 on ferroptosis and mitochondrial dysfunction-mediated apoptosis in SCI.

Methods

The ferric ammonium citrate (FAC)-induced cell model and the SCI rat model were established. The expression of LncRNA OIP5-AS1, miR-128-3p and Nrf2 were transfected to evaluated the effect on the viability and apoptosis of FAC-induced cell. The interaction between LncRNA OIP5-AS1 and miR-128-3p or miR-128-3p and Nrf2 were analyzed. In addition, expressions of markers related to ferroptosis and mitochondrial dysfunction were analyzed in vitro and in vivo. Histopathologic slide staining was used to analyze spinal cord injury in vivo.

Results

LncRNA OIP5-AS1 expression was abnormally down-regulated in FAC-induced SCI cell model and SCI rats. The LncRNA OIP5-AS1 deficiency induced decreased Nrf2 level by less sponging miR-128-3p, thus, aggravating spinal cord injury and inducing more apoptosis, ferroptosis and mitochondrial dysfunction in neural stem cells with SCI. However, overexpression of LncRNA OIP5-AS1 inhibited apoptosis, ferroptosis and mitochondrial dysfunction, thus effectively ameliorating spinal cord injury.

Conclusion

This finding demonstrates that LncRNA OIP5-AS1 overexpression could enhance the recovery of spinal cord injury by regulating the miR-128-3p/Nrf2 axis.

Bridging the gap: a translational perspective in spinal cord injury

Traumatic spinal cord injury (SCI) is a devastating and complex condition to treat with no curative options. In the past few decades, rapid advancements in our understanding of SCI pathophysiology as well as the mergence of new treatments has created more optimism. Focusing on clinical translation, this paper provides a comprehensive overview of SCI through its epidemiology, pathophysiology, currently employed management strategies, and emerging therapeutic approaches. Additionally, it emphasizes the importance of addressing the heavy quality of life (QoL) challenges faced by SCI patients and their desires, providing a basis to tailor patient-centric forms of care. Furthermore, this paper discusses the frequently encountered barriers in translation from preclinical models to clinical settings. It also seeks to summarize significant completed and ongoing SCI clinical trials focused on neuroprotective and neuroregenerative strategies. While developing a cohesive regenerative treatment strategy remains challenging, even modest improvements in sensory and motor function can offer meaningful benefits and motivation for patients coping with this highly debilitating condition.

Influential factors on stem cell therapy success in canine model of spinal cord Injury: A systematic review and meta-analysis

Spinal cord injury (SCI) is a serious medical condition. The search for an effective cure remains a persistent challenge. Current treatments, unfortunately, are unable to sufficiently improve neurological function, often leading to lifelong disability. This systematic review and meta-analysis evaluated the effectiveness of stem cell therapy for SCI using canine models. It also explored the optimal protocol for implementing stem cell therapy. A comprehensive search of studies was conducted from 2000 to October 2022. This study focused on five outcomes: motor function score, histopathology, IHC, western blot, and SEP. The results demonstrated a significant improvement in locomotion post-SCI in dogs treated with stem cell therapy. The therapy also led to an average increase of 3.15 points in the Olby score of the treated dogs compared to the control group. These findings highlights stem cell therapy's potential as a promising SCI treatment. The meta-analysis suggests that using bone marrow stem cells, undergoing neural differentiation in vitro, applying a surgical implantation or intrathecal route of administration, associating matrigel in combination with stem cells, and a waiting period of two weeks before starting treatment can enhance SCI treatment effectiveness.

Functional biomaterials for modulating the dysfunctional pathological microenvironment of spinal cord injury

Spinal cord injury (SCI) often results in irreversible loss of sensory and motor functions, and most SCIs are incurable with current medical practice. One of the hardest challenges in treating SCI is the development of a dysfunctional pathological microenvironment, which mainly comprises excessive inflammation, deposition of inhibitory molecules, neurotrophic factor deprivation, glial scar formation, and imbalance of vascular function. To overcome this challenge, implantation of functional biomaterials at the injury site has been regarded as a potential treatment for modulating the dysfunctional microenvironment to support axon regeneration, remyelination at injury site, and functional recovery after SCI. This review summarizes characteristics of dysfunctional pathological microenvironment and recent advances in biomaterials as well as the technologies used to modulate inflammatory microenvironment, regulate inhibitory microenvironment, and reshape revascularization microenvironment. Moreover, technological limitations, challenges, and future prospects of functional biomaterials to promote efficient repair of SCI are also discussed. This review will aid further understanding and development of functional biomaterials to regulate pathological SCI microenvironment.

The role of nitric oxide and hydrogen sulfide in spinal cord injury: an updated review

Medical gases play an important role in the pathophysiology of human diseases and have received extensive attention for their role in neuroprotection. Common pathological mechanisms of spinal cord injury include excitotoxicity, inflammation, cell death, glial scarring, blood-spinal cord barrier disruption, and ischemia/reperfusion injury. Nitric oxide and hydrogen sulfide are important gaseous signaling molecules in living organisms; their pathological role in spinal cord injury models has received more attention in recent years. This study reviews the possible mechanisms of spinal cord injury and the role of nitric oxide and hydrogen sulfide in spinal cord injury.

Silibinin promotes healing in spinal cord injury through anti-ferroptotic mechanisms

Study Design

Pre-clinical animal experiment.

Objective

In this study, we investigated therapeutic effects of silibinin in a spinal cord injury (SCI) model. In SCI, loss of cells due to secondary damage mechanisms exceeds that caused by primary damage. Ferroptosis, which is iron-dependent non-apoptotic cell death, is shown to be influential in the pathogenesis of SCI.

Methods

The study was conducted as an in vivo experiment using a total of 78 adult male/female Sprague Dawley rats. Groups were as follows: Sham, SCI, deferoxamine (DFO) treatment, and silibinin treatment. There were subgroups with follow-up periods of 24 h, 72 h, and 6 weeks in all groups. Malondialdehyde (MDA), glutathione (GSH), and Fe2+ levels were measured by spectrophotometry. Glutathione peroxidase-4 (GPX4), ferroportin (FPN), transferrin receptor (TfR1), and 4-hydroxynonenal (4-HNE)-modified protein levels were assessed by Western blotting. Functional recovery was assessed using Basso-Beattie-Bresnahan test.

Results

Silibinin achieved significant suppression in MDA and 4-HNE levels compared to the SCI both in 72-h and 6 weeks group (p < 0.05). GSH, GPX4, and FNP levels were found to be significantly higher in the silibinin 24 h, 72 h, and 6 weeks group compared to corresponding SCI groups (p < 0.05). Significant reduction in iron levels was observed in silibinin treated rats in 72 h and 6 weeks group (p < 0.05). Silibinin substantially suppressed TfR1 levels in 24 h and 72 h groups (p < 0.05). Significant difference among recovery capacities was observed as follows: Silibinin > DFO > SCI (p < 0.05).

Conclusion

Impact of silibinin on iron metabolism and lipid peroxidation, both of which are features of ferroptosis, may contribute to therapeutic activity. Within this context, our findings posit silibinin as a potential therapeutic candidate possessing antiferroptotic properties in SCI model. Therapeutic agents capable of effectively and safely mitigating ferroptotic cell death hold the potential to be critical points of future clinical investigations.

Regional biomechanical characterization of the spinal cord tissue: dynamic mechanical response

Characterizing the dynamic mechanical properties of spinal cord tissue is deemed important for developing a comprehensive knowledge of the mechanisms underlying spinal cord injury. However, complex viscoelastic properties are vastly underexplored due to the spinal cord shows heterogeneous properties. To investigate regional differences in the biomechanical properties of spinal cord, we provide a mechanical characterization method (i.e., dynamic mechanical analysis) that facilitates robust measurement of spinal cord ex vivo, at small deformations, in the dynamic regimes. Load-unload cycles were applied to the tissue surface at sinusoidal frequencies of 0.05, 0.10, 0.50 and 1.00 Hz ex vivo within 2 h post mortem. We report the main response features (e.g., nonlinearities, rate dependencies, hysteresis and conditioning) of spinal cord tissue dependent on anatomical origin, and quantify the viscoelastic properties through the measurement of peak force, moduli, and hysteresis and energy loss. For all three anatomical areas (cervical, thoracic, and lumbar spinal cord tissues), the compound, storage, and loss moduli responded similarly to increasing strain rates. Notably, the complex modulus values of ex vivo spinal cord tissue rose nonlinearly with rising test frequency. Additionally, at every strain rate, it was shown that the tissue in the thoracic spinal cord was significantly more rigid than the tissue in the cervical or lumbar spinal cord, with compound modulus values roughly 1.5-times that of the lumbar region. At strain rates between 0.05 and 0.50 Hz, tan δ values for thoracic (that is, 0.26, 0.25, 0.06, respectively) and lumbar (that is, 0.27, 0.25, 0.07, respectively) spinal cord regions were similar, respectively, which were higher than cervical (that is, 0.21, 0.21, 0.04, respectively) region. The conditioning effects tend to be greater at relative higher deformation rates. Interestingly, no marked difference of conditioning ratios is observed among all three anatomical regions, regardless of loading rate. These findings lay a foundation for further comparison between healthy and diseased spinal cord to the future development of spinal cord scaffold and helps to advance our knowledge of neuroscience.

Polydatin attenuated neuropathic pain and motor dysfunction following spinal cord injury in rats by employing its anti-inflammatory and antioxidant effects

Background

Considering the complex pathological mechanisms behind spinal cord injury (SCI) and the adverse effects of present non-approved drugs against SCI, new studies are needed to introduce novel multi-target active ingredients with higher efficacy and lower side effects. Polydatin (PLD) is a naturally occurring stilbenoid glucoside recognized for its antioxidative and anti-inflammatory properties. This study aimed to assess the effects of PLD on sensory-motor function following SCI in rats.

Methods

Following laminectomy and clip compression injury at the thoracic 8 (T8)-T9 level of the spinal cord, rats were randomly assigned to five groups: Sham, SCI, and three groups receiving different doses of PLD treatment (1, 2, and 3 mg/kg). Over 4 weeks, behavioral tests were done such as von Frey, acetone drop, hot plate, Basso-Beattie-Bresnahan, and inclined plane test. At the end of the study, changes in catalase and glutathione activity, nitrite level, activity of matrix metalloproteinase 2 (MMP2) and MMP9 as well as spinal tissue remyelination/neurogenesis, were evaluated.

Results

The results revealed that PLD treatment significantly improved the behavioral performance of the animals starting from the first week after SCI. Additionally, PLD increased catalase, and glutathione levels, and MMP2 activity while reduced serum nitrite levels and MMP9. These positive effects were accompanied by a reduction in the size of the lesion and preservation of neuronal count.

Conclusion

In conclusion, PLD showed neuroprotective effects in SCI rats by employing anti-inflammatory and antioxidant effects, through which improve sensory and motor function.

Repair of spinal cord injury by bone marrow mesenchymal stem cell-derived exosomes: a systematic review and meta-analysis based on rat models

Objective

This study aims to systematically evaluate the efficacy of bone marrow mesenchymal stem cell-derived exosomes (BMSCs-Exo) in improving spinal cord injury (SCI) to mitigate the risk of translational discrepancies from animal experiments to clinical applications.

Methods

We conducted a comprehensive literature search up to March 2024 using PubMed, Embase, Web of Science, and Scopus databases. Two researchers independently screened the literature, extracted data, and assessed the quality of the studies. Data analysis was performed using STATA16 software.

Results

A total of 30 studies were included. The results indicated that BMSCs-Exo significantly improved the BBB score in SCI rats (WMD = 3.47, 95% CI [3.31, 3.63]), inhibited the expression of the pro-inflammatory cytokine TNF-α (SMD = -3.12, 95% CI [-3.57, -2.67]), and promoted the expression of anti-inflammatory cytokines IL-10 (SMD = 2.76, 95% CI [1.88, 3.63]) and TGF-β (SMD = 3.89, 95% CI [3.02, 4.76]). Additionally, BMSCs-Exo significantly reduced apoptosis levels (SMD = -4.52, 95% CI [-5.14, -3.89]), promoted the expression of axonal regeneration markers NeuN cells/field (SMD = 3.54, 95% CI [2.65, 4.42]), NF200 (SMD = 4.88, 95% CI [3.70, 6.05]), and the number of Nissl bodies (SMD = 1.89, 95% CI [1.13, 2.65]), and decreased the expression of astrogliosis marker GFAP (SMD = -5.15, 95% CI [-6.47, -3.82]). The heterogeneity among studies was primarily due to variations in BMSCs-Exo transplantation doses, with efficacy increasing with higher doses.

Conclusion

BMSCs-Exo significantly improved motor function in SCI rats by modulating inflammatory responses, reducing apoptosis, inhibiting astrogliosis, and promoting axonal regeneration. However, the presence of selection, performance, and detection biases in current animal experiments may undermine the quality of evidence in this study.

Molecular mechanisms of spinal cord injury repair across vertebrates: A comparative review

In humans and other adult mammals, axon regeneration is difficult in axotomized neurons. Therefore, spinal cord injury (SCI) is a devastating event that can lead to permanent loss of locomotor and sensory functions. Moreover, the molecular mechanisms of axon regeneration in vertebrates are not very well understood, and currently, no effective treatment is available for SCI. In striking contrast to adult mammals, many nonmammalian vertebrates such as reptiles, amphibians, bony fishes and lampreys can spontaneously resume locomotion even after complete SCI. In recent years, rapid progress in the development of next-generation sequencing technologies has offered valuable information on SCI. In this review, we aimed to provide a comparison of axon regeneration process across classical model organisms, focusing on crucial genes and signalling pathways that play significant roles in the regeneration of individually identifiable descending neurons after SCI. Considering the special evolutionary location and powerful regenerative ability of lamprey and zebrafish, they will be the key model organisms for ongoing studies on spinal cord regeneration. Detailed study of SCI in these model organisms will help in the elucidation of molecular mechanisms of neuron regeneration across species.

AAV6 mediated Gsx1 expression in neural stem progenitor cells promotes neurogenesis and restores locomotor function after contusion spinal cord injury

Genomic screened homeobox 1 (Gsx1 or Gsh1) is a neurogenic transcription factor required for the generation of excitatory and inhibitory interneurons during spinal cord development. In the adult, lentivirus (LV) mediated Gsx1 expression promotes neural regeneration and functional locomotor recovery in a mouse model of lateral hemisection spinal cord injury (SCI). The LV delivery method is clinically unsafe due to insertional mutations to the host DNA. In addition, the most common clinical case of SCI is contusion/compression. In this study, we identify that adeno-associated virus serotype 6 (AAV6) preferentially infects neural stem/progenitor cells (NSPCs) in the injured spinal cord. Using a rat model of contusion SCI, we demonstrate that AAV6 mediated Gsx1 expression promotes neurogenesis, increases the number of neuroblasts/immature neurons, restores excitatory/inhibitory neuron balance and serotonergic neuronal activity through the lesion core, and promotes locomotor functional recovery. Our findings support that AAV6 preferentially targets NSPCs for gene delivery and confirmed Gsx1 efficacy in clinically relevant rat model of contusion SCI.

Imaging demyelinated axons after spinal cord injuries with PET tracer [ 18 F]3F4AP

Spinal cord injuries (SCI) often lead to lifelong disability. Among the various types of injuries, incomplete and discomplete injuries, where some axons remain intact, offer potential for recovery. However, demyelination of these spared axons can worsen disability. Demyelination is a reversible phenomenon, and drugs like 4-aminopyridine (4AP), which target K+ channels in demyelinated axons, show that conduction can be restored. Yet, accurately assessing and monitoring demyelination post-SCI remains challenging due to the lack of suitable imaging methods. In this study, we introduce a novel approach utilizing the positron emission tomography (PET) tracer, [ 18 F]3F4AP, specifically targeting K+ channels in demyelinated axons for SCI imaging. Rats with incomplete contusion injuries were imaged up to one month post-injury, revealing [ 18 F]3F4AP's exceptional sensitivity to injury and its ability to detect temporal changes. Further validation through autoradiography and immunohistochemistry confirmed [ 18 F]3F4AP's targeting of demyelinated axons. In a proof-of-concept study involving human subjects, [ 18 F]3F4AP differentiated between a severe and a largely recovered incomplete injury, indicating axonal loss and demyelination, respectively. Moreover, alterations in tracer delivery were evident on dynamic PET images, suggestive of differences in spinal cord blood flow between the injuries. In conclusion, [ 18 F]3F4AP demonstrates efficacy in detecting incomplete SCI in both animal models and humans. The potential for monitoring post-SCI demyelination changes and response to therapy underscores the utility of [ 18 F]3F4AP in advancing our understanding and management of spinal cord injuries.

Stepwise combined cell transplantation using mesenchymal stem cells and induced pluripotent stem cell-derived motor neuron progenitor cells in spinal cord injury

BACKGROUND

Spinal cord injury (SCI) is an intractable neurological disease in which functions cannot be permanently restored due to nerve damage. Stem cell therapy is a promising strategy for neuroregeneration after SCI. However, experimental evidence of its therapeutic effect in SCI is lacking. This study aimed to investigate the efficacy of transplanted cells using stepwise combined cell therapy with human mesenchymal stem cells (hMSC) and induced pluripotent stem cell (iPSC)-derived motor neuron progenitor cells (iMNP) in a rat model of SCI.

METHODS

A contusive SCI model was developed in Sprague-Dawley rats using multicenter animal spinal cord injury study (MASCIS) impactor. Three protocols were designed and conducted as follows: (Subtopic 1) chronic SCI + iMNP, (Subtopic 2) acute SCI + multiple hMSC injections, and (Main topic) chronic SCI + stepwise combined cell therapy using multiple preemptive hMSC and iMNP. Neurite outgrowth was induced by coculturing hMSC and iPSC-derived motor neuron (iMN) on both two-dimensional (2D) and three-dimensional (3D) spheroid platforms during mature iMN differentiation in vitro.

RESULTS

Stepwise combined cell therapy promoted mature motor neuron differentiation and axonal regeneration at the lesional site. In addition, stepwise combined cell therapy improved behavioral recovery and was more effective than single cell therapy alone. In vitro results showed that hMSC and iMN act synergistically and play a critical role in the induction of neurite outgrowth during iMN differentiation and maturation.

CONCLUSIONS

Our findings show that stepwise combined cell therapy can induce alterations in the microenvironment for effective cell therapy in SCI. The in vitro results suggest that co-culturing hMSC and iMN can synergistically promote induction of MN neurite outgrowth.

Improved Recovery of Complete Spinal Cord Transection by a Plasma-Modified Fibrillar Scaffold

Complete spinal cord injury causes an irreversible disruption in the central nervous system, leading to motor, sensory, and autonomic function loss, and a secondary injury that constitutes a physical barrier preventing tissue repair. Tissue engineering scaffolds are presented as a permissive platform for cell migration and the reconnection of spared tissue. Iodine-doped plasma pyrrole polymer (pPPy-I), a neuroprotective material, was applied to polylactic acid (PLA) fibers and implanted in a rat complete spinal cord transection injury model to evaluate whether the resulting composite implants provided structural and functional recovery, using magnetic resonance (MR) imaging, diffusion tensor imaging and tractography, magnetic resonance spectroscopy, locomotion analysis, histology, and immunofluorescence. In vivo, MR studies evidenced a tissue response to the implant, demonstrating that the fibrillar composite scaffold moderated the structural effects of secondary damage by providing mechanical stability to the lesion core, tissue reconstruction, and significant motor recovery. Histologic analyses demonstrated that the composite scaffold provided a permissive environment for cell attachment and neural tissue guidance over the fibers, reducing cyst formation. These results supply evidence that pPPy-I enhanced the properties of PLA fibrillar scaffolds as a promising treatment for spinal cord injury recovery.

Effects of Moleac 901 after severe spinal cord injury on chronic phase in Wistar rats

Background

MLC901 is a phytopharmaceutical comprising significant compounds that can induce microenvironments conducive to the proliferation and specialization of neural cell progenitors. This study investigates the impact of administering MLC901, reducing the expression of NG2 and caspase-3 and increasing IL-10 levels, as well as histopathological and motor function, after severe spinal cord injury (SCI) in the chronic phase.

Methods

The study employed a randomized post-test-only control group design conducted between February and April 2023 at the Integrated Biomedical Laboratory. The participants in this study were categorized into three distinct groups: normal control, negative control, and therapy. A cohort of 18 rats was utilized for the study, with each group assigned a random allocation of six rats as subjects.

Results

The findings demonstrated a statistically significant disparity in the average NG2 expression (-52.00 ± 20.03; p ≤ 0.05), as well as Caspase-3 expression (-94.89 ± 8.57; p ≤ 0.05), which exhibited a lower magnitude. The levels of IL-10 (8.96 ± 3.98; p ≤ 0.05) were observed to be higher, along with an elevation in BBB score (7.67 ± 0.89; p ≤ 0.05), which was more pronounced in the treatment group compared to the negative control group. The cut-off point for cavitation diameter is determined to be 114.915 μm, exhibiting a sensitivity and specificity of 100%. The area under curve (AUC) value is 1.0. The administration of MLC901 demonstrated a strong positive correlation with the increase in IL-10 levels (B 8.968; p ≤ 0.05), as well as a substantial negative correlation with the decrease in Caspase-3 expression (B -52.000; p ≤ 0.05) and NG2 expression (B -94.892; p ≤ 0.05). The administration of MLC901 via the upregulation of NG2 and Caspase-3 significantly increased the Basso, Beattie, and Bresnahan (BBB) scores.

Conclusions

MLC901 positively affects motor and histopathological outcomes in the chronic phase of severe SCI in the Wistar rat model. These benefits are believed to be achieved by suppressing gliosis, neuroapoptosis, and neuroinflammation processes.

Long ascending propriospinal neurons are heterogenous and subject to spinal cord injury induced anatomic plasticity

Long ascending propriospinal neurons (LAPNs) are a subset of spinal interneurons that provide direct connectivity between distant spinal segments. Here, we focus specifically on an anatomically defined population of "inter-enlargement" LAPNs with cell bodies at L2/3 and terminals at C5/6. Previous studies showed that silencing LAPNs in awake and freely moving animals disrupted interlimb coordination of the hindlimbs, forelimbs, and heterolateral limb pairs. Surprisingly, despite a proportion of LAPNs being anatomically intact post- spinal cord injury (SCI), silencing them improved locomotor function but only influenced coordination of the hindlimb pair. Given the functional significance of LAPNs pre- and post-SCI, we characterized their anatomy and SCI-induced anatomical plasticity. This detailed anatomical characterization revealed three morphologically distinct subsets of LAPNs that differ in soma size, neurite complexity and/or neurite orientation. Following a mild thoracic contusive SCI there was a marked shift in neurite orientation in two of the LAPN subsets to a more dorsoventral orientation, and collateral densities decreased in the cervical enlargement but increased just caudal to the injury epicenter. These post-SCI anatomical changes potentially reflect maladaptive plasticity and an effort to establish new functional inputs from sensory afferents that sprout post-SCI to achieve circuitry homeostasis.

Acetyl-11-keto-beta-boswellic acid modulates macrophage polarization and Schwann cell migration to accelerate spinal cord injury repair in rats

BACKGROUND

Inhibiting secondary inflammatory damage caused by glial cells and creating a stable microenvironment is one of the main strategies to investigate drugs for the treatment of spinal cord injury. Acetyl-11-keto-beta-boswellic acid (AKBA) is the active component of the natural drug boswellia, which has anti-inflammatory and antioxidant effects and offers a possible therapeutic option for spinal cord injury.

METHODS

In this study, a spinal cord injury model was established by crushing spinal cord, respectively, to detect the M1 macrophage inflammatory markers: iNOS, TNF-α, IL-1β, and the M2 macrophage markers CD206, ARG-1, IL-10, and the detection of antioxidant enzymes and MDA. In vitro, macrophages were cultured to verify the main mechanism of the macrophage switch from Nrf2/HO-1 to M2 type by flow cytometry, immunofluorescence, and other techniques. Macrophage and Schwann cell co-culture validated the migration mechanism of Schwann cells promoted by AKBA.

RESULTS

AKBA significantly enhanced the antioxidant enzyme activities of CAT, GSH-Px, T-AOC, and SOD, reduced MDA content, and reduced oxidative damage caused by spinal cord injury via the Nrf2/HO-1 signaling pathway; AKBA mediates Nrf2/HO-1/IL-10, converts macrophages from M1 to M2 type, reduces inflammation, and promotes Schwann cell migration, thereby accelerating the repair of spinal cord injury in rats.

CONCLUSIONS

Our work demonstrates that AKBA can attenuate oxidative stress as well as the secondary inflammatory injury caused by macrophages after SCI, promote Schwann cell migration to the injury site, and thus accelerate the repair of the injured spinal cord.

Identification of marker genes for spinal cord injury

Introduction

Spinal cord injury (SCI) is a profoundly disabling and devastating neurological condition, significantly impacting patients' quality of life. It imposes unbearable psychological and economic pressure on both patients and their families, as well as placing a heavy burden on society.

Methods

In this study, we integrated datasets GSE5296 and GSE47681 as training groups, analyzed gene variances between sham group and SCI group mice, and conducted Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis based on the differentially expressed genes. Subsequently, we performed Weighted Gene Correlation Network Analysis (WGCNA) and Lasso regression analyses.

Results

We identified four characteristic disease genes: Icam1, Ch25h, Plaur and Tm4sf1. We examined the relationship between SCI and immune cells, and validated the expression of the identified disease-related genes in SCI rats using PCR and immunohistochemistry experiments.

Discussion

In conclusion, we have identified and verified four genes related to SCI: Icam1, Ch25h, Plaur and Tm4sf1, which could offer insights for SCI treatment.

Local delivery of AdipoRon from self-assembled microparticles to inhibit myelin lipid uptake and to promote lipid efflux from rat macrophages

Objective.Abundant lipid-laden macrophages are found at the injury site after spinal cord injury (SCI). These cells have been suggested to be pro-inflammatory and neurotoxic. AdipoRon, an adiponectin receptor agonist, has been shown to promote myelin lipid efflux from mouse macrophage foam cells. While it is an attractive therapeutic strategy, systemic administration of AdipoRon is likely to exert off-target effects. In addition, the pathophysiology after SCI in mice is different from that in humans, whereas rat and human SCI share similar functional and histological outcomes. In this study, we evaluated the effects of AdipoRon on rat macrophage foam cells and developed a drug delivery system capable of providing sustained local release of AdipoRon to the injured spinal cord.Approach.Rat macrophages were treated with myelin debris to generate anin vitromodel of SCI foam cells, and the effects of AdipoRon treatment on myelin uptake and efflux were studied. AdipoRon was then loaded into and released from microparticles made from dextran sulfate and fibrinogen for sustained release.Main results.AdipoRon treatment not only significantly promotes efflux of metabolized myelin lipids, but also inhibits uptake of myelin debris. Myelin debris alone does not appear to be inflammatory, but myelin debris treatment potentiates inflammation when administered along with pro-inflammatory lipopolysaccharide (LPS) and interferon-γ. AdipoRon significantly attenuated myelin lipid-induced potentiation of inflammation. Bioactive AdipoRon can be released in therapeutic doses from microparticles.Significance.These data suggest that AdipoRon is a promising therapeutic capable of reducing lipid accumulation via targeting both myelin lipid uptake and efflux, which potentially addresses chronic inflammation following SCI. Furthermore, we developed microparticle-based drug delivery systems for local delivery of AdipoRon to avoid deleterious side effects. This is the first study to release AdipoRon from drug delivery systems designed to reduce lipid accumulation and inflammation in reactive macrophages after SCI.

The GLP-1 receptor agonist exenatide improves recovery from spinal cord injury by inducing macrophage polarization toward the M2 phenotype

Although a wide variety of mechanisms take part in the secondary injury phase of spinal cord injury (SCI), inflammation is the most important factor implicated in the sequelae after SCI. Being central to the inflammation reaction, macrophages and their polarization are a topic that has garnered wide interest in the studies of SCI secondary injury. The glucagon-like peptide 1 (GLP-1) receptor agonist exenatide has been shown to enhance the endoplasmic reticulum stress response and improve motor function recovery after spinal cord injury (SCI). Since exenatide has also been reported to induce the production of M2 cells in models of cerebral infarction and neurodegenerative diseases, this study was conducted to examine the effects of exenatide administration on the inflammation process that ensues after spinal cord injury. In a rat contusion model of spinal cord injury, the exenatide group received a subcutaneous injection of 10 μg exenatide immediately after injury while those in the control group received 1 mL of phosphate-buffered saline. Quantitative RT-PCR and immunohistochemical staining were used to evaluate the effects of exenatide administration on the macrophages infiltrating the injured spinal cord, especially with regard to macrophage M1 and M2 profiles. The changes in hind limb motor function were assessed based on Basso, Beattie, Bresnahan locomotor rating scale (BBB scale) scores. The improvement in BBB scale scores was significantly higher in the exenatide group from day 7 after injury and onwards. Quantitative RT-PCR revealed an increase in the expression of M2 markers and anti-inflammatory interleukins in the exenatide group that was accompanied by a decrease in the expression of M1 markers and inflammatory cytokines. Immunohistochemical staining showed no significant difference in M1 macrophage numbers between the two groups, but a significantly higher number of M2 macrophages was observed in the exenatide group on day 3 after injury. Our findings suggest that exenatide administration promoted the number of M2-phenotype macrophages after SCI, which may have led to the observed improvement in hind limb motor function in a rat model of SCI.

Sarsasapogenin regulates the immune microenvironment through MAPK/NF-kB signaling pathway and promotes functional recovery after spinal cord injury

Spinal cord injury (SCI) occurs as a result of traumatic events that damage the spinal cord, leading to motor, sensory, or autonomic function impairment. Sarsasapogenin (SA), a natural steroidal compound, has been reported to have various pharmacological applications, including the treatment of inflammation, diabetic nephropathy, and neuroprotection. However, the therapeutic efficacy and underlying mechanisms of SA in the context of SCI are still unclear. This research aimed to investigate the therapeutic effects and mechanisms of SA against SCI by integrating network pharmacology analysis and experimental verification. Network pharmacology results suggested that SA may effectively treat SCI by targeting key targets such as TNF, RELA, JUN, MAPK14, and MAPK8. The underlying mechanism of this treatment may involve the MAPK (JNK) signaling pathway and inflammation-related signaling pathways such as TNF and Toll-like receptor signaling pathways. These findings highlight the therapeutic potential of SA in SCI treatment and provide valuable insights into its molecular mechanisms of action. In vivo experiments confirmed the reparative effect of SA on SCI in rats and suggested that SA could repair SCI by modulating the immune microenvironment. In vitro experiments further investigated how SA regulates the immune microenvironment by inhibiting the MAPK/NF-kB pathways. Overall, this study successfully utilized a combination of network pharmacology and experimental verification to establish that SA can regulate the immune microenvironment via the MAPK/NF-kB signaling pathway, ultimately facilitating functional recovery from SCI. Furthermore, these findings emphasize the potential of natural compounds from traditional Chinese medicine as a viable therapy for SCI treatment.

Syringaresinol promotes the recovery of spinal cord injury by inhibiting neuron apoptosis via activating the ubiquitination factor E4B/AKT Serine/Threonine kinase signal pathway

Spinal cord injury (SCI) is a serious traumatic disease with no effective treatment. This study aimed to explore the therapeutic effect of syringaresinol on SCI. First, the potential targets and associated signaling pathways of syringaresinol were predicted by bioinformatics analysis and molecular docking. Second, MTT was employed to evaluate cell proliferation rate, Western blot was performed to detect protein expression, RT-qPCR was conducted to detect mRNA expression levels, flow cytometry and 5-ethynyl-2'-deoxyuridine (EDU) staining were used to determine cell apoptosis, and immunofluorescence and immunohistochemistry were used to estimate the expression of RNA binding fox-1 homolog 3 and clipped caspase 3. Basso-Beattie-Bresnahan scores and inclined plate tests were conducted to analyze hindlimb locomotor function. Results showed that syringaresinol could inhibit the apoptosis of glutamate-treated SHSY5Y cells by upregulating the expression of ubiquitination factor E4B (UBE4B) and activating the AKT serine/threonine kinase (AKT) signaling pathway. This effect can be rescued by UBE4B knockdown or AKT pathway inhibition. Syringaresinol remarkably improved locomotor function and increased neuronal survival in SCI rats. Our results suggested that syringaresinol could promote locomotor functional recovery by reducing neuronal apoptosis by activating the UBE4B/AKT signaling pathway.

Effects of Valproic Acid Therapy on Rats with Spinal Cord Injury: A Systematic Review and Meta-Analysis

OBJECTIVE

To systematically evaluate the efficacy of valproic acid (VPA) in rats with spinal cord injury (SCI) to reduce the risk of clinical conversion and provide a valuable reference for future animal and clinical studies.

METHODS

We searched scientific databases, including PubMed, Ovid-Embase, Web of Science, and Scopus databases. The relevant literature was searched from the establishment date of the database to June 28, 2023. The search results were screened, data were extracted, and the quality of the literature was evaluated independently by 2 reviewers.

RESULTS

Among 656 nonduplicated references, 14 articles were included for meta-analysis. The summary results showed that the overall Basso, Beattie and Bresnahan scores of the VPA intervention group were significantly higher than those in the control group at 1-6 weeks after VPA intervention. Subgroup analysis showed that the injury model, administration dose, rat strain, country of study, or follow-up duration had no significant effect on the efficacy of VPA on rats with SCI. In addition, mesh analysis showed that high doses of the VPA group had a better effect on SCI rats, compared with the low dose group and the medium dose group.

CONCLUSIONS

To date, this is the first systematic evaluation of the potential effects of VPA on motor recovery in rats with SCI. We concluded that VPA can promote motor recovery in rats with SCI, and higher doses of VPA seem to be more effective in rats with SCI. However, the limited quality and sample of included studies reduced the application of this meta-analysis. In the future, more high-quality, direct comparative studies are needed to explore this issue in depth.

Small Extracellular Vesicles Released from miR-211-5p-Overexpressed Bone Marrow Mesenchymal Stem Cells Ameliorate Spinal Cord Injuries in Rats

Spinal cord injury (SCI) has become one of the common and serious diseases affecting patients' motor functions. The small extracellular vesicles secreted by bone marrow mesenchymal stem cells (BMSCs) have shown a promising prospect for the treatment of neurological diseases. BMSCs were collected from rat bones. Osteogenic and adipogenic differentiation of BMSCs was further determined. Small extracellular vesicles were obtained by high-speed centrifugation. Dual-luciferase reporter assay was performed to demonstrate the targeting of miR-211-5p to the cyclooxygenase 2 (COX2) mRNA. qRT-PCR and Western blot assay were used for the detection of the mRNA and protein expression. ELISA was performed to estimate the levels of proinflammatory factors in spinal cord tissues. Our results showed that miR-211-5p targeted COX2 mRNA and regulated the protein expression of COX2 in BMSCs. Extracellular vesicles released from miR-211-5p-overexpressed BMSCs ameliorated SCI-induced motor dysfunction and motor evoked potential impairments. Extracellular vesicles released from miR-211-5p-overexpressed BMSCs ameliorated SCI-induced COX2 expression and related inflammatory responses. In conclusion, small extracellular vesicles released from miR-211-5p-overexpressed BMSCs ameliorate spinal cord injuries in rats.

[Exosomes from ectoderm mesenchymal stem cells inhibits lipopolysaccharide-induced microglial M1 polarization and promotes survival of H2O2-exposed PC12 cells by suppressing inflammatory response and oxidative stress]

OBJECTIVE

To investigate the potential value of exosomes derived from rat ectoderm mesenchymal stem cells (EMSCs-exo) for repairing secondary spinal cord injury.

METHODS

EMSCs-exo were obtained using ultracentrifugation from EMSCs isolated from rat nasal mucosa, identified by transmission electron microscope, nanoparticle tracking analysis (NTA), and Western blotting, and quantified using the BCA method. Neonatal rat microglia purified by differential attachment were induced with 100 μg/L lipopolysaccharide (LPS) and treated with 37.5 or 75 mg/L EMSCs-exo. PC12 cells were exposed to 400 μmol/L H2O2 and treated with EMSCs-exo at 37.5 or 75 mg/L. The protein and mRNA expressions of Arg1 and iNOS in the treated cells were determined with Western blotting and qRT- PCR, and the concentrations of IL- 6, IL-10, and IGF-1 in the supernatants were measured with ELISA. The viability and apoptosis of PC12 cells were detected using CCK-8 assay and flow cytometry.

RESULTS

The isolated rat EMSCs showed high expressions of nestin, CD44, CD105, and vimentin. The obtained EMSCs-exo had a typical cup-shaped structure under transmission electron microscope with an average particle size of 142 nm and positivity for CD63, CD81, and TSG101 but not vimentin. In LPS-treated microglia, EMSCs-exo treatment at 75 mg/L significantly increased Arg1 protein level and lowered iNOS protein expression (P < 0.05). EMSCs-exo treatment at 75 mg/L, as compared with the lower concentration at 37.5 mg/L, more strongly increased Arg1 mRNA expression and IGF-1 and IL-10 production and decreased iNOS mRNA expression and IL-6 production in LPS-induced microglia, and more effectively promoted cell survival and decreased apoptosis rate of H2O2-induced PC12 cells (P < 0.05).

CONCLUSION

EMSCs-exo at 75 mg/L can effectively reduce the proportion of M1 microglia and alleviate neuronal apoptosis under oxidative stress to promote neuronal survival, suggesting its potential in controlling secondary spinal cord injury.

Krishnan L, Abelson KSP. Refinement of the motorised laminectomy-assisted rat spinal cord injury model by analgesic treatment

Usage and reporting of analgesia in animal models of spinal cord injury (SCI) have been sparse and requires proper attention. The majority of experimental SCI research uses rats as an animal model. This study aimed to probe into the effects of some commonly used regimens with NSAIDs and opioids on well-being of the rats as well as on the functional outcome of the model. This eight-week study used forty-two female Wistar rats (Crl: WI), randomly and equally divided into 6 treatment groups, viz. I) tramadol (5mg/kg) and buprenorphine (0.05mg/kg); II) carprofen (5mg/kg) and buprenorphine (0.05mg/kg); III) carprofen (5mg/kg); IV) meloxicam (1mg/kg) and buprenorphine (0.05mg/kg); V) meloxicam (1mg/kg); and VI) no analgesia (0.5 ml sterile saline). Buprenorphine was administered twice daily whereas other treatments were given once daily for five days post-operatively. Injections were given subcutaneously. All animals underwent dental burr-assisted laminectomy at the T10-T11 vertebra level. A custom-built calibrated spring-loaded 200 kilodynes force deliverer was used to induce severe SCI. Weekly body weight scores, Rat Grimace Scale (RGS), and dark-phase home cage activity were used as markers for well-being. Weekly Basso Beattie and Bresnahan (BBB) scores served as markers for functionality together with Novel Object Recognition test (NOR) at week 8 and terminal histopathology using area of vacuolisation and live neuronal count from the ventral horns of spinal cord. It was concluded that the usage of analgesia improved animal wellbeing while having no effects on the functional aspects of the animal model in comparison to the animals that received no analgesics.

PKR inhibitor protects spinal cord injury through mitigating endoplasmic reticulum stress and pyroptosis

OBJECTIVES

The goal of the study was to reveal the regulatory role of protein kinase R (PKR) in spinal cord injury (SCI), a devasting disorder of the neurological system, and to elucidate its potential mechanism.

METHODS

The established animal and cellular models of SCI were treated by the PKR inhibitor C12. Histological injury and tissue apoptosis were assessed via H&E staining and TUNEL assays, respectively. Basso-Beattie-Bresnahan (BBB) scoring as well as forelimb grip strength tests were employed to evaluate functional recovery. The production of ROS and cytokines were appraised via their related commercial kits. Western blot and immunofluorescence assay were used to examine protein expression. CCK-8 method was used to assay cell activity. Co-immunoprecipitation assay was conducted to measure the affinity of PKR with STAT1.

RESULTS

PKR expression was enhanced following SCI, and the PKR inhibitor C16 mitigated histological injury, cell apoptosis and water content in spinal cord, and improved function recovery following SCI. Meanwhile, C16 attenuated ER stress, pyroptosis, NLRP3 inflammasome and inflammation in mice with SCI and in BV-2 cells challenged with LPS. Additionally, PKR interacted with STAT1 in BV-2 cells, and STAT1 knockdown inhibited ER stress, pyroptosis and inflammation in BV-2 cells challenged with LPS. The protective role of C16 in BV-2 cells exposed to LPS were partly abolished by STAT1 overexpression.

CONCLUSION

PKR inhibition might be a prospective effective approach to attenuating SCI and accelerating function recovery through modulating microglial pyroptosis and ER stress.

Improvement of neurogenic urinary dysfunctions in female rats treated with an injection of botulinum toxin A at the epicenter of the spinal cord injured site

OBJECTIVE

To assess the effect of an injection of botulinum toxin A (BoNT/A) at the epicenter of the spinal cord injury (SCI) site on the recovery of lower urinary tract function in female rats with thoracic SCI.

MATERIALS AND METHODS

Twenty-four female Wistar rats with Sham (laminectomy at T8/T9 level) or SCI (at T8/T9; 30 g compression for 5 s) were assigned into Sham-SS (injected with 5 µL of saline solution), Sham-BoNT/A (injected with 15 pg/rat, equivalent to 7.5 Units/kg of BoNT/A in 5 µL volume), SCI-SS (injured and injected with saline), SCI-BoNT/A (injured and injected with BoNT/A), N = 6 per group. Weekly evaluation of stereotyped micturition behavior, hind-limb nociception, and locomotor activity was performed 1 week before and during 6 weeks after surgery. Subsequently, all groups underwent simultaneous electromyography of the external urethral sphincter (EUS-EMG) and cystometric (CMG) studies.

RESULTS

A compression SCI at the T8/T9 thoracic level significantly impairs sensory and locomotive functions, as well as stereotyped micturition behavior. However, these impairments were improved by BoNT/A injection after SCI. Neither injections of saline solution nor BoNT/A had an appreciable effect on the same parameters evaluated in the Sham groups. The combined EUS-EMG and CMG evaluations revealed important improvements of lower urinary tract physiology, particularly a reduction in the frequency of non-voiding contractions and the properties of EUS bursting activity indicated as the amplitude of the EUS-EMG signal and duration of burst electrical activity during effective voiding.

CONCLUSION

The severe impairments on sensory and locomotive functions as well stereotyped micturition caused by an SCI could be potentially attenuated by an injection of a small amount of BoNT/A directly into the epicenter of the SCI region. A reduction in the release of neurotoxic neurotransmitters requiring the SNARE complex may be the mechanism triggered by BoNT/A to reduce neurotoxicity and hyperexcitability created in the SCI area to improve the survival of spinal cord cells involved in micturition.

Stem cell-derived exosomes for traumatic spinal cord injury: a systematic review and network meta-analysis based on a rat model

BACKGROUND AIMS

Exosome therapy for traumatic spinal cord injury (TSCI) is a current research hotspot, but its therapeutic effect and the best source of stem cells for exosomes are unclear.

METHODS

The Web of Science, PubMed, Embase, Cochrane, and Scopus databases were searched from inception to March 28, 2023. Literature screening, data extraction and risk of bias assessment were performed independently by two investigators.

RESULTS

A total of 40 studies were included for data analysis. The findings of our traditional meta-analysis indicate that exosomes derived from stem cells significantly improve the motor function of TSCI at various time points (1 week: weighted mean difference [WMD] = 1.58, 95% confidence interval [CI] 0.87-2.30] 2 weeks: WMD = 3.12, 95% CI 2.64-3.61; 3 weeks: WMD = 4.44, 95% CI 3.27-5.60; 4 weeks: WMD = 4.54, 95% CI 3.42-5.66). Four kinds of stem cell-derived exosomes have been studied: bone marrow mesenchymal stem cells, adipose mesenchymal stem cells, umbilical cord mesenchymal stem cells and neural stem cells. The results of the network meta-analysis showed that there was no significant statistical difference in the therapeutic effect among the exosomes derived from four kinds of stem cells at different treatment time points. Although exosomes derived from bone marrow mesenchymal stem cells are the current research focus, exosomes derived from neural stem cells have the most therapeutic potential and should become the focus of future attention.

CONCLUSIONS

The exosomes derived from stem cells can significantly improve the motor function of TSCI rats, and the exosomes derived from neural stem cells have the most therapeutic potential. However, the lower evidence quality of animal studies limits the reliability of experimental results, emphasizing the need for more high-quality, direct comparative studies to explore the therapeutic efficacy of exosomes and the best source of stem cells.

Hydrogel and Nanomedicine-Based Multimodal Therapeutic Strategies for Spinal Cord Injury

Spinal cord injury (SCI) is a severe neurodegenerative disease caused by mechanical and biological factors, manifesting as a loss of motor and sensory functions. Inhibition of injury expansion and even reversal of injury in the acute damage stage of SCI are important strategies for treating this disease. Hydrogels and nanoparticle (NP)-based drugs are the most effective, widely studied, and clinically valuable therapeutic strategies in the field of repair and regeneration. Hydrogels are 3D flow structures that fill the pathological gaps in SCI and provide a microenvironment similar to that of the spinal cord extracellular matrix for nerve cell regeneration. NP-based drugs can easily penetrate the blood-spinal cord barrier, target SCI lesions, and are noninvasive. Hydrogels and NPs as drug carriers can be loaded with various drugs and biological therapeutic factors for slow release in SCI lesions. They help drugs function more efficiently by exerting anti-inflammatory, antioxidant, and nerve regeneration effects to promote the recovery of neurological function. In this review, the use of hydrogels and NPs as drug carriers and the role of both in the repair of SCI are discussed to provide a multimodal strategic reference for nerve repair and regeneration after SCI.

Biomarkers for predicting the severity of spinal cord injury by proteomic analysis

Purpose

Currently, there is a shortage of the protein biomarkers for classifying spinal cord injury (SCI) severity. We attempted to explore the candidate biomarkers for predicting SCI severity.

Methods

SCI rat models with mild, moderate, and severe injury were constructed with an electro-mechanic impactor. The behavior assessment and pathological examinations were conducted before and after SCI. Then, quantitative liquid chromatography-mass spectrometry (LC-MS/MS) was performed in spinal cord tissues with different extents of injury. The differentially expressed proteins (DEPs) in SCI relative to controls were identified, followed by Mfuzz clustering, function enrichment analysis, and protein-protein interaction (PPI) network construction. The differential changes of candidate proteins were validated by using a parallel reaction monitoring (PRM) assay.

Results

After SCI modeling, the motor function and mechanical pain sensitivity of SCI rats were impaired, dependent on the severity of the injury. A total of 154 DEPs overlapped in the mild, moderate, and severe SCI groups, among which 82 proteins were classified in clusters 1, 2, 3, 5, and 6 with similar expression patterns at different extents of injury. DEPs were closely related to inflammatory response and significantly enriched in the IL-17 signaling pathway. PPI network showed that Fgg (Fibrinogen gamma chain), Fga (Fibrinogen alpha chain), Serpinc1 (Antithrombin-III), and Fgb (Fibrinogen beta chain) in cluster 1 were significant nodes with the largest degrees. The upregulation of the significant nodes in SCI samples was validated by PRM.

Conclusion

Fgg, Fga, and Fgb may be the putative biomarkers for assessing the extent of SCI.

Phase 1 safety, tolerability, pharmacokinetics and pharmacodynamic results of KCL-286, a novel retinoic acid receptor-β agonist for treatment of spinal cord injury, in male healthy participants

AIMS

KCL-286 is an orally available agonist that activates the retinoic acid receptor (RAR) β2, a transcription factor which stimulates axonal outgrowth. The investigational medicinal product is being developed for treatment of spinal cord injury (SCI). This adaptive dose escalation study evaluated the tolerability, safety and pharmacokinetics and pharmacodynamic activity of KCL-286 in male healthy volunteers to establish dosing to be used in the SCI patient population.

METHODS

The design was a double blind, randomized, placebo-controlled dose escalation study in 2 parts: a single ascending dose adaptive design with a food interaction arm, and a multiple ascending dose design. RARβ2 mRNA expression was evaluated in white blood cells.

RESULTS

At the highest single and multiple ascending doses (100 mg), no trends or clinically important differences were noted in the incidence or intensity of adverse events (AEs), serious AEs or other safety assessments with none leading to withdrawal from the study. The AEs were dry skin, rash, skin exfoliation, raised liver enzymes and eye disorders. There was an increase in mean maximum observed concentration and area under the plasma concentration-time curve up to 24 h showing a trend to subproportionality with dose. RARβ2 was upregulated by the investigational medicinal product in white blood cells.

CONCLUSION

KCL-286 was well tolerated by healthy human participants following doses that exceeded potentially clinically relevant plasma exposures based on preclinical in vivo models. Target engagement shows the drug candidate activates its receptor. These findings support further development of KCL-286 as a novel oral treatment for SCI.

Catalytic antioxidant nanoparticles mitigate secondary injury progression and promote functional recovery in spinal cord injury model

Traumatic spinal cord injury exacerbates disability with time due to secondary injury cascade triggered largely by overproduction of reactive oxygen species (ROS) at the lesion site, causing oxidative stress. This study explored nanoparticles containing antioxidant enzymes (antioxidant NPs) to neutralize excess ROS at the lesion site and its impact. When tested in a rat contusion model of spinal cord injury, a single dose of antioxidant NPs, administered intravenously three hours after injury, effectively restored the redox balance at the lesion site, interrupting the secondary injury progression. This led to reduced spinal cord tissue inflammation, apoptosis, cavitation, and inhibition of syringomyelia. Moreover, the treatment reduced scar tissue forming collagen at the lesion site, protected axons from demyelination, and stimulated lesion healing, with further analysis indicating the formation of immature neurons. The ultimate effect of the treatment was improved motor and sensory functions and rapid post-injury weight loss recovery. Histological analysis revealed activated microglia in the spinal cord displaying rod-shaped anti-inflammatory and regenerative phenotype in treated animals, contrasting with amoeboid inflammatory and degenerative phenotype in untreated control. Overall data suggest that restoring redox balance at the lesion site shifts the dynamics in the injured spinal cord microenvironment from degenerative to regenerative, potentially by promoting endogenous repair mechanisms. Antioxidant NPs show promise to be developed as an early therapeutic intervention in stabilizing injured spinal cord for enhanced recovery.

Challenges in Translating Regenerative Therapies for Spinal Cord Injury

Regenerating the injured spinal cord is a substantial challenge with many obstacles that need to be overcome to achieve robust functional benefits. This abundance of hurdles can partly explain the limited success when applying regenerative intervention treatments in animal models and/or people. In this article, we elaborate on a few of these obstacles, starting with the applicability of animal models and how they compare to the clinical setting. We then discuss the requirement for combinatorial interventions and the associated problems in experimental design, including the addition of rehabilitative training. The article expands on differences in lesion sizes and locations between humans and common animal models, and how this difference can determine the success or failure of an intervention. An additional and frequently overlooked problem in the translation of interventions that applies beyond the field of neuroregeneration is the reporting bias and the lack of transparency in reporting findings. New data mandates are tackling this problem and will eventually result in a more balanced view of the field. Finally, we will discuss strategies to negotiate the challenging course of successful translation to facilitate successful translation of regeneration promoting interventions.

Low oral dose of 4-methylumbelliferone reduces glial scar but is insufficient to induce functional recovery after spinal cord injury

Spinal cord injury (SCI) induces the upregulation of chondroitin sulfate proteoglycans (CSPGs) at the glial scar and inhibits neuroregeneration. Under normal physiological condition, CSPGs interact with hyaluronan (HA) and other extracellular matrix on the neuronal surface forming a macromolecular structure called perineuronal nets (PNNs) which regulate neuroplasticity. 4-methylumbelliferone (4-MU) is a known inhibitor for HA synthesis but has not been tested in SCI. We first tested the effect of 4-MU in HA reduction in uninjured rats. After 8 weeks of 4-MU administration at a dose of 1.2 g/kg/day, we have not only observed a reduction of HA in the uninjured spinal cords but also a down-regulation of CS glycosaminoglycans (CS-GAGs). In order to assess the effect of 4-MU in chronic SCI, six weeks after Th8 spinal contusion injury, rats were fed with 4-MU or placebo for 8 weeks in combination with daily treadmill rehabilitation for 16 weeks to promote neuroplasticity. 4-MU treatment reduced the HA synthesis by astrocytes around the lesion site and increased sprouting of 5-hydroxytryptamine fibres into ventral horns. However, the current dose was not sufficient to suppress CS-GAG up-regulation induced by SCI. Further adjustment on the dosage will be required to benefit functional recovery after SCI.

Repeated intravenous infusion of mesenchymal stem cells enhances recovery of motor function in a rat model with chronic spinal cord injury

Spinal cord injury (SCI) can cause paralysis with a high disease burden with limited treatment options. A single intravenous infusion of mesenchymal stem cells (MSCs) improves motor function in rat SCI models, possibly through the induction of axonal sprouting and remyelination. Repeated infusions (thrice at weekly intervals) of MSCs were administered to rats with chronic SCI to determine if multiple-dosing regimens enhance motor improvement. Chronic SCI rats were randomized and infused with vehicle (vehicle), single MSC injection at week 6 (MSC-1) or repeatedly injections of MSCs at 6, 7, and 8 weeks (MSC-3) after SCI induction. In addition, a single high dose of MSCs (HD-MSC) equivalent to thrice the single dose was infused at week 6. Locomotor function, light and electron microscopy, immunohistochemistry and ex vivo diffusion tensor imaging were performed. Repeated infusion of MSCs (MSC-3) provided the greatest functional recovery compared to single and single high-dose infusions. The density of remyelinated axons in the injured spinal cord was the greatest in the MSC-3 group, followed by the MSC-1, HD-MSC and vehicle groups. Increased sprouting of the corticospinal tract and serotonergic axon density was the greatest in the MSC-3 group, followed by MSC-1, HD-MSC, and vehicle groups. Repeated infusion of MSCs over three weeks resulted in greater functional improvement than single administration of MSCs, even when the number of infused cells was tripled. MSC-treated rats showed axonal sprouting and remyelination in the chronic phase of SCI.

Changes in respiratory structure and function after traumatic cervical spinal cord injury: observations from spinal cord and brain

Respiratory difficulties and mortality following severe cervical spinal cord injury (CSCI) result primarily from malfunctions of respiratory pathways and the paralyzed diaphragm. Nonetheless, individuals with CSCI can experience partial recovery of respiratory function through respiratory neuroplasticity. For decades, researchers have revealed the potential mechanism of respiratory nerve plasticity after CSCI, and have made progress in tissue healing and functional recovery. While most existing studies on respiratory plasticity after spinal cord injuries have focused on the cervical spinal cord, there is a paucity of research on respiratory-related brain structures following such injuries. Given the interconnectedness of the spinal cord and the brain, traumatic changes to the former can also impact the latter. Consequently, are there other potential therapeutic targets to consider? This review introduces the anatomy and physiology of typical respiratory centers, explores alterations in respiratory function following spinal cord injuries, and delves into the structural foundations of modified respiratory function in patients with CSCI. Additionally, we propose that magnetic resonance neuroimaging holds promise in the study of respiratory function post-CSCI. By studying respiratory plasticity in the brain and spinal cord after CSCI, we hope to guide future clinical work.

Risk factors for chronic ankle instability after first episode of lateral ankle sprain: A retrospective analysis of 362 cases

BACKGROUND

Chronic ankle instability (CAI) is a common sequela following an acute lateral ankle sprain (LAS). To treat an acute LAS more effectively and efficiently, it is important to identify patients at substantial risk for developing CAI. This study identifies magnetic resonance imaging (MRI) manifestations for predicting CAI development after a first episode of LAS and explores appropriate clinical indications for ordering MRI scans for these patients.

METHODS

All patients with a first-episode LAS who received plain radiograph and MRI scanning within the first 2 weeks after LAS from December 1, 2017 to December 1, 2019 were identified. Data were collected using the Cumberland Ankle Instability Tool at final follow-up. Demographic and other related clinical variables, including age, sex, body mass index, and treatment were also recorded. Univariable and multivariable analyses were performed successively to identify risk factors for CAI after first-episode LAS.

RESULTS

A total 131 out of 362 patients with a mean follow-up of 3.0 ± 0.6 years (mean ± SD; 2.0-4.1 years) developed CAI after first-episode LAS. According to multivariable regression, development of CAI after first-episode LAS was associated with 5 prognostic factors: age (odds ratio (OR) = 0.96, 95% confidence interval (95%CI): 0.93-1.00, p = 0.032); body mass index (OR = 1.09, 95%CI: 1.02-1.17, p = 0.009); posterior talofibular ligament injury (OR = 2.17, 95%CI: 1.05-4.48, p = 0.035); large bone marrow lesion of the talus (OR = 2.69, 95%CI: 1.30-5.58, p = 0.008), and Grade 2 effusion of the tibiotalar joint (OR = 2.61, 95%CI: 1.39-4.89, p = 0.003). When patients had at least 1 positive clinical finding in the 10-m walk test, anterior drawer test, or inversion tilt test, they had a 90.2% sensitivity and 77.4% specificity in terms of detecting at least 1 prognostic factor by MRI.

CONCLUSION

MRI scanning is valuable in predicting CAI after first-episode LAS for those patients with at least 1 positive clinical finding in the 10-m walk test, anterior drawer test, and inversion tilt test. Further prospective and large-scale studies are necessary for validation.

Umbilical mesenchymal stem cell-derived exosomes promote spinal cord functional recovery through the miR-146b/TLR4 -mediated NF-κB p65 signaling pathway in rats

Spinal cord injury (SCI) is an incurable central nervous system impairment that lack of efficient treatment. Exosomes derived from mesenchymal stem cells (MSCs) are widely applied in disease treatment. This work aimed to determine the promising therapeutic effects of MSC-derived exosomal miRNA146b on SCI. A rat spinal cord injury (SCI) model and lipopolysaccharide (LPS)-induced PC12 cell model were established. Exosomes were extracted from human umbilical cord mesenchymal stem cells (hUCMSCs). The identification of exosomes was performed by using transmission electronic microscope (TEM) and nanoparticle tracking analysis (NTA). Hematoxylin and eosin (HE) staining and TUNEL assay were performed to assess tissue damage and apoptosis, respectively. ELISA was performed to detect levels of inflammatory cytokines. Cell viability was checked by cell counting kit 8 (CCK-8). Gene expression and protein levels were detected by qPCR and western blotting assay. The interaction between miR-146 b and Toll-like receptor 4 (TLR4) was assessed by luciferase reporter gene assay. The hUCMSC-derived exosomes could notably alleviate the spinal cord injury and cell apoptosis. The exosomal miR-146 b treatment suppressed the release of IL-1 β, IL-6, and TNFα. The miR-146 b suppressed the expression of TLR4, directly interact with the 3'-untranslated region (3'UTR) of TLR4, and inactivated the nuclear factor κB (NF-κB) signaling. The hUCMSCs-derived exosomal miR-146 b protects neurons from spinal cord injury through targeting the TLR4 and inactivating the NF-κB signaling. Our findings supported the application of hUCMSCs-derived exosomal miR-146 b for the protection of SCI.

Thermosensitive hydrogel-based GPR124 delivery strategy for rebuilding blood-spinal cord barrier

Spinal cord injury (SCI) causes blood-spinal cord barrier (BSCB) disruption, leading to secondary damage, such as hemorrhagic infiltration, inflammatory response, and neuronal cell death. It is of great significance to rebuild the BSCB at the early stage of SCI to alleviate the secondary injury for better prognosis. Yet, current research involved in the reconstruction of BSCB is insufficient. Accordingly, we provide a thermosensitive hydrogel-based G protein-coupled receptor 124 (GPR124) delivery strategy for rebuilding BSCB. Herein, we firstly found that the expression of GPR124 decreased post-SCI and demonstrated that treatment with recombinant GPR124 could partially alleviate the disruption of BSCB post-SCI by restoring tight junctions (TJs) and promoting migration and tube formation of endothelial cells. Interestingly, GPR124 could also boost the energy metabolism of endothelial cells. However, the absence of physicochemical stability restricted the wide usage of GPR124. Hence, we fabricated a thermosensitive heparin-poloxamer (HP) hydrogel that demonstrated sustained GPR124 production and maintained the bioactivity of GPR124 (HP@124) for rebuilding the BSCB and eventually enhancing functional motor recovery post-SCI. HP@124 hydrogel can encapsulate GPR124 at the lesion site by injection, providing prolonged release, preserving wounded tissues, and filling injured tissue cavities. Consequently, it induces synergistically efficient integrated regulation by blocking BSCB rupture, decreasing fibrotic scar formation, minimizing inflammatory response, boosting remyelination, and regenerating axons. Mechanistically, giving GPR124 activates energy metabolism via elevating the expression of phosphoenolpyruvate carboxykinase 2 (PCK2), and eventually restores the poor state of endothelial cells. This research demonstrated that early intervention by combining GPR124 with bioactive multifunctional hydrogel may have tremendous promise for restoring locomotor recovery in patients with central nervous system disorders, in addition to a translational approach for the medical therapy of SCI.

Porcine Models of Spinal Cord Injury

Large animal models of spinal cord injury may be useful tools in facilitating the development of translational therapies for spinal cord injury (SCI). Porcine models of SCI are of particular interest due to significant anatomic and physiologic similarities to humans. The similar size and functional organization of the porcine spinal cord, for instance, may facilitate more accurate evaluation of axonal regeneration across long distances that more closely resemble the realities of clinical SCI. Furthermore, the porcine cardiovascular system closely resembles that of humans, including at the level of the spinal cord vascular supply. These anatomic and physiologic similarities to humans not only enable more representative SCI models with the ability to accurately evaluate the translational potential of novel therapies, especially biologics, they also facilitate the collection of physiologic data to assess response to therapy in a setting similar to those used in the clinical management of SCI. This review summarizes the current landscape of porcine spinal cord injury research, including the available models, outcome measures, and the strengths, limitations, and alternatives to porcine models. As the number of investigational SCI therapies grow, porcine SCI models provide an attractive platform for the evaluation of promising treatments prior to clinical translation.

Comparative efficacy of five most common traditional Chinese medicine monomers for promoting recovery of motor function in rats with blunt spinal cord injury: a network meta-analysis

Objective

This research employed a network meta-analysis (NMA) to examine the effectiveness of five traditional Chinese medicine (TCM) monomers for promoting motor function recovery in rats with blunt spinal cord injury (SCI).

Methods

Wangfang, China National Knowledge Infrastructure, Web of Science, Embase, Chinese Scientific Journal Database, PubMed, and the Chinese Biomedical Literature Databases were searched for retrieving relevant articles published from their inception to December 2022. Two reviewers performed screening of search results, data extraction, and literature quality assessment independently.

Results

For this meta-analysis, 59 publications were included. Based on the recovery of motor function at weeks 1, 2, 3, and 4 in NMA, almost all TCM groups had significantly increased positive effects than the negative control animals. In terms of cumulative probability, the tanshinone IIA (TIIA) group ranked first in restoring motor function in the first week after blunt SCI, and the resveratrol (RSV) group ranked first during the last 3 weeks.

Conclusion

The NMA revealed that TCM monomers could effectively restore motor function in the rat model of blunt SCI. In rats with blunt SCI, TIIA may be the most effective TCM monomer during the first week, whereas RSV may be the most effective TCM monomer during the last 3 weeks in promoting motor function recovery. For better evidence reliability in preclinical investigations and safer extrapolation of those findings into clinical settings, further research standardizing the implementation and reporting of animal experiments is required.

Systematic Review Registration

https://inplasy.com/, identifier INPLASY202310070.

Conducting spinal cord injury model with clip compression in rodents: Pearls and pitfalls

Research on spinal cord injuries is an important and living topic that raises many critical questions that need to be addressed. While numerous articles have compiled and compared various models of spinal cord injuries, there is limited comprehensive guide with clear instructions available for researchers who are unfamiliar with clip compression model. This model creates acute compression damage in spinal cord, which aims to mimic the nature of traumatic spinal cord damage in humans. Purpose of this article is to share our experience on clip compression model, with experience gained from more than 150 animals, and to provide guidance for researchers with lack of experience who wish to design studies with this model. We have defined several key variables, as well as the difficulties that may arise when applying this model.-Proper preparation, good infrastructure and necessary tools and knowledge of anatomy related is essential to the success of this model.-Good exposure with non-bleeding surgical site is key factor for surgical step.-Postoperative care is particularly challenging, and researchers should consider extending their studies over a reasonable time period to ensure that appropriate care could be provided.

Targeting of MALT1 May Improve Functional Recovery and Attenuate Microglia M1 Polarization-Mediated Neuroinflammation During Spinal Cord Injury

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) is involved in neural injury, neuroinflammation, microglia activation, and polarization, while its function in spinal cord injury (SCI) remains unclear. Thus, this study aimed to evaluate the role of MALT1 modification on SCI recovery and its underlying mechanism. SCI surgery or sham surgery was performed in Sprague-Dawley rats. Then, MALT1 knockdown or negative control lentivirus was injected into SCI rats. Subsequently, MALT1 expression, locomotor capability, neural injury, markers for microglia activation and polarization, inflammatory cytokine expressions, and nuclear factor (NF)-κB pathway were detected. SCI rats exhibited higher MALT1 expression, microglia activation and M1 polarization, neuroinflammation, and NF-κB pathway activation, while worse locomotor capacity compared to sham rats (all P < 0.05). In SCI rats, MALT1 knockdown alleviated Basso, Beattie, and Bresnahan score from 10 to 28 days and attenuated HE staining reflected neural injury (all P < 0.05). Besides, MALT1 knockdown declined the number of IBA1⁺ cells, IBA1⁺ iNOS⁺ cells, and IBA1⁺ CD86⁺ cells, while enhanced the number of IBA1⁺ Arg1⁺ cells and IBA1⁺ CD206⁺ cells in SCI rats (all P < 0.05). Meanwhile, MALT1 knockdown declined the expressions of IL-1β, IL-6, and TNF-α in SCI (all P < 0.05), but did not affect IL-10 expression (P > 0.05). Furthermore, MALT1 knockdown suppressed NF-κB pathway activation validated by immunofluorescence staining and western blot assays (all P < 0.05). MALT1 knockdown improves functional recovery, attenuates microglia activation, M1 polarization, and neuroinflammation via inhibiting NF-κB pathway in SCI.

A finite element model of contusion spinal cord injury in rodents

Traumatic spinal cord injuries result from high impact forces acting on the spine and are proceeded by an extensive secondary inflammatory response resulting in motor, sensory, and autonomic dysfunction. Experimental in vivo traumatic spinal cord injuries in rodents using a contusion model have been extremely useful in elucidating the underlying pathophysiology of these injuries. However, the relationship between the pathophysiology and the biomechanical factors is still not well understood. Therefore, the aim of this research is to provide a comprehensive analysis of the biomechanics of traumatic spinal cord injury in a rat contusion model. This is achieved through the development and validation of a finite element model of the thoracic rat spinal cord and subsequently simulating controlled cortical impact-induced traumatic spinal cord injury. The effects of impactor velocity, depth, and geometry on the resulting stresses and strains within the spinal cord are investigated. Our results show that increasing impactor depth results in larger stresses and strains within the spinal cord tissue as expected. Further, for the first time ever our results show that impactor geometry (spherical versus cylindrical) plays an important role in the distribution and magnitude of stresses and strains within the cord. Therefore, finite element modelling can be a powerful tool used to predict stresses and strains that occur in spinal cord tissue during trauma.

Effects of tetramethylpyrazine treatment in a rat model of spinal cord injury: A systematic review and meta-analysis

Spinal cord injury (SCI) is a serious disabling condition that leads to the loss of motor, sensory, and excretory functions, seriously affecting the quality of life of patients and imposing a heavy burden on the patient's family and society. There is currently a lack of effective treatments for SCI. However, a large number of experimental studies have shown beneficial effects of tetramethylpyrazine (TMP). We performed a meta-analysis to systematically evaluate the effects of TMP on neurological and motor function recovery in rats with acute SCI. English (PubMed, Web of Science, and EMbase) and Chinese (CNKI, Wanfang, VIP, and CBM) databases were searched for literature related to TMP treatment in rats with SCI published until October 2022. Two researchers independently read the included studies, extracted the data, and evaluated their quality. A total of 29 studies were included, and a risk of bias assessment revealed that the methodological quality of the included studies was low. The results of the meta-analysis showed that the Basso, Beattie, and Bresnahan (BBB; n = 429, pooled mean difference [MD] = 3.44, 95% confidence interval [CI] = 2.67 to 4.22, p < 0.00001) and inclined plane test (n = 133, pooled MD = 5.60, 95% CI = 3.78 to 7.41, p < 0.00001) scores of rats treated with TMP were significantly higher than those in the control group at 14 days after SCI. TMP treatment also resulted in a significant reduction in malondialdehyde (MDA; n = 128, pooled MD = -2.03, 95% CI = -3.47 to -0.58, p < 0.00001) and increased superoxide dismutase (SOD; n = 128, pooled MD = 5.02, 95% CI = 2.39 to 7.65, p < 0.00001). Subgroup analysis indicated that different doses of TMP did not improve the BBB scale and inclined plane test angles. In conclusion, this review showed that TMP can improve SCI outcomes; however, in view of the limitations of the included studies, larger and high-quality studies are required for verification.

The potential effects of polyunsaturated ω-3 fatty acids on spinal cord injury: A systematic review & meta-analysis of preclinical evidence

Polyunsaturated fatty acids (PUFAs) have received attention for their anti-inflammatory and antioxidant properties. Preclinical studies have investigated the efficacy of PUFAs in animal models of spinal cord injury (SCI) to determine if these properties can translate to neuroprotection and locomotor recovery. Findings from such studies have been promising, suggesting PUFAs as potential treatments against the neurological dysfunction induced by SCI. This systematic review and meta-analysis sought to investigate the efficacy of PUFAs for promoting locomotor recovery in animal models of SCI. PubMed, Web of Science and Embase (Ovid) were searched for relevant papers and those that examined the restorative effects of PUFAs on locomotor recovery in preclinical SCI models were included in our analysis. A random effects meta-analysis (restricted maximum likelihood estimator) was employed. A total of 28 studies were included and the results showed the claim that PUFAs have a beneficial therapeutic effect for promoting locomotor recovery (SMD = 1.037, 95% CI = 0.809-1.2644, p = <0.001) and cell survival (SMD = 1.101, 95% CI = 0.889-1.313, p = <0.001) in animal models of SCI. No significant differences for the secondary outcomes of neuropathic pain and lesion volume. Moderate asymmetry was observed in the funnel plots for locomotor recovery, cell survival and neuropathic pain measures, suggesting publication bias. Trim-and-fill analysis estimated 13, 3, 0 and 4 missing studies for locomotor recovery, cell survival, neuropathic pain, and lesion volume, respectively. A modified CAMARADES checklist was also used to assess risk of bias, showing that the median score for all included papers was 4 out of a possible 7.

Spatiotemporal microvascular changes following contusive spinal cord injury

Microvascular integrity is disrupted following spinal cord injury (SCI) by both primary and secondary insults. Changes to neuronal structures are well documented, but little is known about how the capillaries change and recover following injury. Spatiotemporal morphological information is required to explore potential treatments targeting the microvasculature post-SCI to improve functional recovery. Sprague-Dawley rats were given a T10 moderate/severe (200 kDyn) contusion injury and were perfuse-fixed at days 2, 5, 15, and 45 post-injury. Unbiased stereology following immunohistochemistry in four areas (ventral and dorsal grey and white matter) across seven spinal segments (n = 4 for each group) was used to calculate microvessel density, surface area, and areal density. In intact sham spinal cords, average microvessel density across the thoracic spinal cord was: ventral grey matter: 571 ± 45 mm-2, dorsal grey matter: 484 ± 33 mm-2, ventral white matter: 90 ± 8 mm-2, dorsal white matter: 88 ± 7 mm-2. Post-SCI, acute microvascular disruption was evident, particularly at the injury epicentre, and spreading three spinal segments rostrally and caudally. Damage was most severe in grey matter at the injury epicentre (T10) and T11. Reductions in all morphological parameters (95-99% at day 2 post-SCI) implied vessel regression and/or collapse acutely. Transmission electron microscopy (TEM) revealed disturbed aspects of neurovascular unit fine structure at day 2 post-SCI (n = 2 per group) at T10 and T11. TEM demonstrated a more diffuse and disrupted basement membrane and wider intercellular clefts at day 2, suggesting a more permeable blood spinal cord barrier and microvessel remodelling. Some evidence of angiogenesis was seen during recovery from days 2 to 45, indicated by increased vessel density, surface area, and areal density at day 45. These novel results show that the spinal cord microvasculature is highly adaptive following SCI, even at chronic stages and up to three spinal segments from the injury epicentre. Multiple measures of gross and fine capillary structure from acute to chronic time points provide insight into microvascular remodelling post-SCI. We have identified key vascular treatment targets, namely stabilising damaged capillaries and replacing destroyed vessels, which may be used to improve functional outcomes following SCI in the future.