Advanced Age and Neurotrauma Diminish Glutathione and Impair Antioxidant Defense after Spinal Cord Injury

Biomaterial-based strategies: a new era in spinal cord injury treatment

Enhancing neurological recovery and improving the prognosis of spinal cord injury have gained research attention recently. Spinal cord injury is associated with a complex molecular and cellular microenvironment. This complexity has prompted researchers to elucidate the underlying pathophysiological mechanisms and changes and to identify effective treatment strategies. Traditional approaches for spinal cord injury repair include surgery, oral or intravenous medications, and administration of neurotrophic factors; however, the efficacy of these approaches remains inconclusive, and serious adverse reactions continue to be a concern. With advancements in tissue engineering and regenerative medicine, emerging strategies for spinal cord injury repair now involve nanoparticle-based nanodelivery systems, scaffolds, and functional recovery techniques that incorporate biomaterials, bioengineering, stem cell, and growth factors as well as three-dimensional bioprinting. Ideal biomaterial scaffolds should not only provide structural support for neuron migration, adhesion, proliferation, and differentiation but also mimic the mechanical properties of natural spinal cord tissue. Additionally, these scaffolds should facilitate axon growth and neurogenesis by offering adjustable topography and a range of physical and biochemical cues. The three-dimensionally interconnected porous structure and appropriate physicochemical properties enabled by three-dimensional biomimetic printing technology can maximize the potential of biomaterials used for treating spinal cord injury. Therefore, correct selection and application of scaffolds, coupled with successful clinical translation, represent promising clinical objectives to enhance the treatment efficacy for and prognosis of spinal cord injury. This review elucidates the key mechanisms underlying the occurrence of spinal cord injury and regeneration post-injury, including neuroinflammation, oxidative stress, axon regeneration, and angiogenesis. This review also briefly discusses the critical role of nanodelivery systems used for repair and regeneration of injured spinal cord, highlighting the influence of nanoparticles and the factors that affect delivery efficiency. Finally, this review highlights tissue engineering strategies and the application of biomaterial scaffolds for the treatment of spinal cord injury. It discusses various types of scaffolds, their integrations with stem cells or growth factors, and approaches for optimization of scaffold design.

Unveiling the effects of Rosa canina oligosaccharide liposome on neuropathic pain and motor dysfunction following spinal cord injury in rats: relevance to its antioxidative effects

Background

Spinal cord injury (SCI) is a leading cause of sensorimotor disorders, impacting millions of people globally. The absence of effective treatments and the side effects of existing medications highlight the need for innovative research into new therapeutic compounds.

Purpose

Given the critical role of oxidative stress in the development of SCI and the antioxidant properties of oligosaccharides in other neurological disorders, this study focuses on the role of oxidative stress in SCI and explores the potential of a novel oligosaccharide nanoformulation derived from Rosa canina (Oligo-L).

Materials and methods

Oligo-L was formulated using soy lecithin as the phospholipid and the characterization included size, zeta potential, morphology, and drug loading efficiency. Then 35 Wistar male rats were divided into five groups of Sham, SCI, and Oligo-L (10 μL intrathecal injection of 15, 30, and 45 mg/mL). An aneurysm clip was used to induce compression injury of the SCI and Oligo-L groups. Sensory-motor functions were evaluated weekly for 4 weeks using tests such as the BBB scale, inclined plane, acetone drop, hot plate, von Frey, and monitoring of weight changes. Additionally, oxidative stress markers and histological changes were examined to evaluate changes in nitrite, glutathione, catalase, and neuronal survival.

Results and discussion

The findings indicated that Oligo-L treatment led to significant improvements in neuropathic pain, and motor function performance and weight of the animals from the first week post-SCI. Oligo-L also enhanced catalase and glutathione levels while reducing serum nitrite levels, contributing to neuronal preservation. Additionally, Oligo-L increased neuronal survival in the both ventral (motor neurons) and dorsal (sensory neurons) horns of the spinal cord.

Conclusion

Overall, Oligo-L, characterized by its beneficial physicochemical properties, showed promising potential as a neuroprotective agent and facilitated the recovery of sensory and motor functions after SCI.

Neuronal Dual-Specificity Phosphatase 26 Inhibition via Reactive-Oxygen-Species Responsive Mesoporous-Silica-Loaded Hydrogel for Spinal Cord Injury Repair

Spinal cord injury (SCI) remains a formidable challenge in biomedical research, as the silencing of intrinsic regenerative signals in most spinal neurons results in an inability to reestablish neural circuits. In this study, we found that neurons with low axonal regeneration after SCI showed decreased extracellular signal-regulated kinase (ERK) phosphorylation levels. However, the expression of dual specificity phosphatase 26 (DUSP26)─which negatively regulates ERK phosphorylation─was reduced considerably in neurons undergoing spontaneous axonal regeneration. Therefore, we developed a system named F10@MS@UV-HG that integrated a DUSP26-specific inhibitor into reactive oxygen species-responsive nanoparticles and embedded them in photosensitive hydrogels. This system effectively downregulated DUSP26 expression in primary neurons and enhanced ERK phosphorylation, ultimately promoting axonal outgrowth. When transplanted into an SCI mouse model, the system achieved sustained drug release, specifically targeting the DUSP26/ERK/ELK1 pathway in the spinal neurons and facilitating short-term axonal regeneration. Additionally, long-term repair effects─including improved myelination and enhanced motor function─were evident in the SCI mice transplanted with F10@MS@UV-HG. The results suggested that activating ERK signaling by modulating DUSP26 expression in neurons after SCI could effectively promote axonal regeneration and functional recovery. Thus, the developed F10@MS@UV-HG system exhibits enormous potential as a therapeutic approach for patients with SCI.

Cytosolic phospholipase A2 in infiltrating monocyte derived macrophages does not impair recovery after spinal cord injury in female mice

Spinal cord injury (SCI) leads to permanent motor and sensory loss that is exacerbated by intraspinal inflammation and persists months to years after injury. After SCI, monocyte-derived macrophages (MDMs) infiltrate the lesion to aid in myelin-rich debris clearance. During debris clearance, MDMs adopt a proinflammatory phenotype that exacerbates neurodegeneration and hinders recovery. The underlying cause of the lipid-mediated MDM phenotype shift is unclear. Our previous work suggests that cytosolic phospholipase A2 (cPLA2) plays a role in the proinflammatory potentiating effect of myelin on macrophages in vitro. Cytosolic phospholipase A2 (cPLA2) frees arachidonic acid from phospholipids, generating eicosanoids that play an important role in inflammation, immunity, and host defense. cPLA2 is expressed in macrophages along with multiple other cell types after SCI, and cPLA2 inhibition has been reported to both reduce and exacerbate secondary injury pathology recovery. The role of cPLA2 in MDMs after SCI is not fully understood. We hypothesize that cPLA2 activation in MDMs after SCI contributes to secondary injury. Here, we report that cPLA2 plays an important role in the myelin-induced inflammatory macrophage phenotype in vitro using macrophages derived from cPLA2 knockout bone marrow. Furthermore, to investigate the role of cPLA2 in MDMs after SCI, we generated female bone marrow chimeras using cPLA2 knock-out donors and assessed locomotor recovery using the Basso Mouse Scale (BMS), CatWalk gait analysis system, and horizontal ladder task over six weeks. We also evaluated tissue sparing and intralesional axon density six weeks after injury. cPLA2 KO chimeras did not display altered locomotor recovery or tissue pathology after SCI compared to WT chimera controls. These data suggest that although cPLA2 plays a critical role in myelin-mediated potentiation of proinflammatory macrophage activation in vitro, it may not contribute to secondary injury pathology in vivo after SCI.

Cytosolic Phospholipase A2 in Infiltrating Monocyte-Derived Macrophages Does Not Impair Recovery After Spinal Cord Injury in Female Mice

Spinal cord injury (SCI) leads to permanent motor and sensory loss that is exacerbated by intraspinal inflammation that persists months to years after injury. After SCI, monocyte-derived macrophages (MDMs) infiltrate the lesion to aid in myelin-rich debris clearance. During debris clearance, MDMs adopt a proinflammatory phenotype that exacerbates neurodegeneration and hinders recovery. The underlying cause of the lipid-mediated MDM phenotype shift is unclear. Our previous work suggests that cytosolic phospholipase A2 (cPLA2) plays a role in the proinflammatory potentiating effect of myelin on macrophages in vitro. Cytosolic phospholipase A2 (cPLA2) frees arachidonic acid from phospholipids, generating eicosanoids that play an important role in inflammation, immunity, and host defense. cPLA2 is expressed in macrophages along with multiple other cell types after SCI, and cPLA2 inhibition has been reported to both reduce and exacerbate secondary injury pathology recovery. The role of cPLA2 in MDMs after SCI is not fully understood. We hypothesize that cPLA2 activation in MDMs after SCI contributes to secondary injury. Here, we report that cPLA2 plays an important role in the myelin-induced inflammatory macrophage phenotype in vitro using macrophages derived from cPLA2 knockout bone marrow. Furthermore, to investigate the role of cPLA2 in MDMs after SCI, we generated female bone marrow chimeras using cPLA2 knock-out donors and assessed locomotor recovery using the Basso Mouse Scale (BMS), CatWalk gait analysis system, and horizontal ladder task over six weeks. We also evaluated tissue sparing and intralesional axon density six weeks after injury. cPLA2 KO chimeras did not display altered locomotor recovery or tissue pathology after SCI compared to WT chimera controls. These data suggest that although cPLA2 plays a critical role in myelin-mediated potentiation of proinflammatory macrophage activation in vitro, it may not contribute to secondary injury pathology in vivo after SCI.

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.

Glutathione effect on functional and histological recovery after spinal cord injury in rats

OBJECTIVE

The aim of this study was to evaluate the GSH effect on functional and histological recovery after experimental spinal cord injury in rats.

METHODS

Forty Wistar rats were subjected to spinal cord injury through the Multicenter Animal Spinal Cord Injury Study (MASCIS) Impactor system. The rats were sorted and divided into four groups, as follows: Group 1 ‒ Laminectomy and spinal cord injury; Group 2 ‒ Laminectomy, spinal cord injury and Saline Solution (SS) 0.9%; Group 3 ‒ Laminectomy, spinal cord injury, and GSH; and Group 4 ‒ lLaminectomy without spinal cord injury. GSH and SS were administered intraperitoneally. Groups 1 and 4 received no intervention.

RESULTS

The rats were evaluated for locomotor function recovery at seven different times by the Basso, Beattie, and Bresnahan (BBB) scale on days 2, 7, 14, 21, 28, 35, and 42 after the spinal cord injury. On day 42, the rats were sacrificed to analyze the histological findings of the injured spinal cord. In the group submitted to GSH, our experimental study revealed better functional scores on the BBB scale, horizontal ladder scale, and cranial and caudal axon count. The differences found were statistically significant in BBB scores and axonal count analysis.

CONCLUSION

This study demonstrated that using glutathione in experimental spinal trauma can lead to better functional recovery and improved axonal regeneration rate in Wistar rats submitted to experimental spinal cord injury.

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.

Effects of Acute Ethanol Intoxication on Spinal Cord Injury Outcomes in Female Mice

Abstract Approximately one in three traumatic spinal cord injuries (SCIs) occurs during or shortly after the consumption of alcohol. A small number of retrospective clinical studies report variable effects of alcohol intoxication on mortality, neurological recovery, and complications after SCI. Some of these studies demonstrate a protective effect of alcohol intoxication on SCI outcomes, whereas others show an increased complication risk. Pre-clinical studies in rat, ferret, and feline SCI models report a detrimental effect of ethanol intoxication on hemorrhage, motor recovery, and biochemical markers of tissue injury. However, no studies to date have investigated the neuropathological consequences of ethanol intoxication at the time of SCI or the reciprocal effect of SCI on ethanol metabolism. Therefore, we combined a pre-clinical mouse model of acute ethanol intoxication and experimental vertebral level T9 contusion SCI to investigate their interactive effects in female mice. We first investigated the effect of SCI on ethanol metabolism and found that T9 SCI does not alter ethanol metabolism. However, we did find that isoflurane anesthesia significantly slowed ethanol metabolism independent of SCI. We also determined how acute ethanol intoxication at the time of SCI alters locomotor recovery and lesion pathology. Using the Basso Mouse Scale (BMS) and CatWalk XT Gait Analysis System, we assessed locomotor recovery for 6 weeks after injury and observed that acute ethanol intoxication at the time of injury did not alter locomotor recovery. We also found no effect of ethanol intoxication on heat hyperalgesia development. There was, however, a detrimental effect of ethanol on tissue sparing after SCI. Therefore, we conclude that acute alcohol intoxication at the time of injury may contribute to the neuropathological consequences of SCI.

Neuroinflammation in the Evolution of Motor Function in Stroke and Trauma Patients: Treatment and Potential Biomarkers

Neuroinflammation has a significant impact on different pathologies, such as stroke or spinal cord injury, intervening in their pathophysiology: expansion, progression, and resolution. Neuroinflammation involves oxidative stress, damage, and cell death, playing an important role in neuroplasticity and motor dysfunction by affecting the neuronal connection responsible for motor control. The diagnosis of this pathology is performed using neuroimaging techniques and molecular diagnostics based on identifying and measuring signaling molecules or specific markers. In parallel, new therapeutic targets are being investigated via the use of bionanomaterials and electrostimulation to modulate the neuroinflammatory response. These novel diagnostic and therapeutic strategies have the potential to facilitate the development of anticipatory patterns and deliver the most beneficial treatment to improve patients' quality of life and directly impact their motor skills. However, important challenges remain to be solved. Hence, the goal of this study was to review the implication of neuroinflammation in the evolution of motor function in stroke and trauma patients, with a particular focus on novel methods and potential biomarkers to aid clinicians in diagnosis, treatment, and therapy. A specific analysis of the strengths, weaknesses, threats, and opportunities was conducted, highlighting the key challenges to be faced in the coming years.

A dynamic nomogram for predicting the probability of irreversible neurological dysfunction after cervical spinal cord injury: research based on clinical features and MRI data

BACKGROUND

Irreversible neurological dysfunction (IND) is an adverse event after cervical spinal cord injury (CSCI). However, there is still a shortage of objective criteria for the early prediction of neurological function. We aimed to screen independent predictors of IND and use these findings to construct a nomogram that could predict the development of neurological function in CSCI patients.

METHODS

Patients with CSCI attending the Affiliated Hospital of Southwest Medical University between January 2014 and March 2021 were included in this study. We divided the patients into two groups: reversible neurological dysfunction (RND) and IND. The independent predictors of IND in CSCI patients were screened using the regularization technique to construct a nomogram, which was finally converted into an online calculator. Concordance index (C-index), calibration curves analysis and decision curve analysis (DCA) evaluated the model's discrimination, calibration, and clinical applicability. We tested the nomogram in an external validation cohort and performed internal validation using the bootstrap method.

RESULTS

We enrolled 193 individuals with CSCI in this study, including IND (n = 75) and RND (n = 118). Six features, including age, American spinal injury association Impairment Scale (AIS) grade, signal of spinal cord (SC), maximum canal compromise (MCC), intramedullary lesion length (IMLL), and specialized institution-based rehabilitation (SIBR), were included in the model. The C-index of 0.882 from the training set and its externally validated value of 0.827 demonstrated the model's prediction accuracy. Meanwhile, the model has satisfactory actual consistency and clinical applicability, verified in the calibration curve and DCA.

CONCLUSION

We constructed a prediction model based on six clinical and MRI features that can be used to assess the probability of developing IND in patients with CSCI.

Improving translatability of spinal cord injury research by including age as a demographic variable

Pre-clinical and clinical spinal cord injury (SCI) studies differ in study design, particularly in the demographic characteristics of the chosen population. In clinical study design, criteria such as such as motor scores, neurological level, and severity of injury are often key determinants for participant inclusion. Further, demographic variables in clinical trials often include individuals from a wide age range and typically include both sexes, albeit historically most cases of SCI occur in males. In contrast, pre-clinical SCI models predominately utilize young adult rodents and typically use only females. While it is often not feasible to power SCI clinical trials to test multi-variable designs such as contrasting different ages, recent pre-clinical findings in SCI animal models have emphasized the importance of considering age as a biological variable prior to human experiments. Emerging pre-clinical data have identified case examples of treatments that diverge in efficacy across different demographic variables and have elucidated several age-dependent effects in SCI. The extent to which these differing or diverging treatment responses manifest clinically can not only complicate statistical findings and trial interpretations but also may be predictive of worse outcomes in select clinical populations. This review highlights recent literature including age as a biological variable in pre-clinical studies and articulates the results with respect to implications for clinical trials. Based on emerging unpredictable treatment outcomes in older rodents, we argue for the importance of including age as a biological variable in pre-clinical animal models prior to clinical testing. We believe that careful analyses of how age interacts with SCI treatments and pathophysiology will help guide clinical trial design and may improve both the safety and outcomes of such important efforts.

Immunoglobulin G is Increased in the Injured Spinal Cord in a Sex and Age Dependent Manner

There are limited studies examining age and sex as biological variables in the pathophysiology of spinal cord injury (SCI). The use of older animals and sex-balanced groups in SCI models is increasingly prioritized to better match clinical demographics. Including older animals in SCI studies is technically challenging, and outcomes are unpredictable with respect to biological and treatment responses. Incidental discoveries that are unrelated to the question under investigation often emerge while including age and sex as biological variables. When probing tissue homogenates on Western blots of 4- and 14-month-old (MO) mice, we identified a sex- and age-dependent increase in immunoglobulin G (IgG) within the spinal cords of older, 14-MO mice acutely after SCI, with females having more IgG compared with males. We further probed to determine whether differences in hemorrhage exist between sexes or ages by evaluating hemoglobin within spinal homogenates. Differences in hemoglobin between sexes and ages were not consistently observed. Because IgG was elevated in an age- and sex-dependent manner without of evidence of differences in hemorrhage, our findings point to potential pre-existing differences in IgG within mouse plasma in an age- and sex-dependent manner. This report has identified age- and sex-dependent differences in infiltrating IgG into the injured spinal cord environment that may affect injury and recovery processes. Our findings highlight that systemic contributions to SCI can be sex- and age-dependent and illustrate the value of reporting incidental discoveries.