Spinal Cord Contusion Injury Model Research Articles

Berberine attenuates neuronal ferroptosis via the AMPK–NRF2–HO-1-signaling pathway in spinal cord-injured rats

Ferroptosis, characterized by iron-dependent accumulation of lipid peroxides, plays an important role in spinal cord injury (SCI). Berberine (BBR), as a lipid peroxide scavenger, has been widely used in treating other diseases; however, its role in ferroptosis has not been fully elucidated. Therefore, here, to test our hypothesis that BBR can reduce the severity of SCI and promote motor function recovery by inhibiting neuronal ferroptosis, we evaluated the changes in ferroptosis-related indicators after BBR administration by establishing a cellular ferroptosis model and an SCI contusion model. We found that BBR administration significantly reduces lipid peroxidation damage, maintains normal mitochondrial function, reduces excessive accumulation of iron ions, enhances antioxidant capacity, and activates the ferroptosis defense system in vivo and in vitro. Mechanistically, BBR alleviates neuronal ferroptosis by inducing adenosine monophosphate-activated protein kinase (AMPK) phosphorylation and up-regulating nuclear factor erythroid 2-related factor 2 (NRF2) and heme oxygenase-1 (HO-1) protein expression to promote glutathione production. BBR administration also significantly improves motor function recovery in SCI rats. Meanwhile, applying the AMPK inhibitor Compound C blocks the neuroprotective and all other effects of BBR. Collectively, our findings demonstrate that BBR can attenuate neuronal ferroptosis after SCI by activating the AMPK–NRF2–HO-1 pathway.

Genetic deletion of the apoptosis associated speck like protein containing a card in LysM+ macrophages attenuates spinal cord injury by regulating M1/M2 polarization through ASC-dependent inflammasome signaling axis

Apoptosis associated speck like protein containing a card (ASC), the key adaptor protein of the assembly and activation of canonical inflammasomes, has been found to play a significant role in neuroinflammation after spinal cord injury (SCI). The previous studies indicated that widely block or knockout ASC can ameliorate SCI. However, ASC is ubiquitously expressed in infiltrated macrophages and local microglia, so further exploration is needed on which type of cell playing the key role. In this study, using the LysMcre;Ascflox/flox mice with macrophage-specifc ASC conditional knockout (CKO) and contusive SCI model, we focus on evaluating the specific role of ASC in lysozyme 2 (LysM)+ myeloid cells (mainly infiltrated macrophages) in this pathology. The results revealed that macrophage-specifc Asc CKO exhibited the follow effects: (1) A significant reduction in the numbers of infiltrated macrophages in the all phases of SCI, and activated microglia in the acute and subacute phases. (2) A significant reduction in ASC, caspase-1, interleukin (IL)-1β, and IL-18 compared to control mice. (3) In the acute and subacute phases of SCI, M1 subset differentiation was inhibited, and M2 differentiation was increased. (4) Histology and hindlimb motor recoveries were improved. In conclusion, this study elucidates that macrophage-specific ASC CKO can improve nerve function recovery after SCI by regulating M1/M2 polarization through inhibiting ASC-dependent inflammasome signaling axis. This indicates that ASC in peripheral infiltrated macrophages may play an important role in SCI pathology, at least in mice, could be a potential target for treatment.

A N‐Cadherin Nano‐Antagonist Hydrogel Enhances Recovery From Spinal Cord Injury by Impeding Glial Scarring

AbstractThe role of glial scars in the pathophysiology of spinal cord injury (SCI) is widely recognized, as they pose physical barriers against axonal regeneration and persistent chronic inflammation by releasing cytotoxic agents, thereby impeding nerve repair. Consequently, preventing glial scarring has emerged as an important therapeutic objective in SCI management. Following SCI, astrocytes undergo a phenotypic transition into scar‐forming astrocytes, which critically depends on the activation of inflammatory responses and the integrin‐N‐cadherin pathway. To explore improved SCI treatment, a nano‐antagonist hydrogel (Nano‐ant Gel), comprising N‐cadherin nano‐antagonists and a polyphenol hydrogel designed to inhibit glial scarring by mitigating inflammatory response and modulating astrocyte behavior, thereby facilitating spinal cord‐injury repair, is developed and characterized. The hydrogel exhibits notable anti‐inflammatory properties, specific calcium ion‐adsorption capabilities, and antagonistic effects against N‐cadherin, effectively impeding the formation and aggregation of scar‐forming astrocytes. Its efficacy is comprehensively assessed using a model of contusive SCI, with which it effectively inhibits glial scar formation and promotes axonal regeneration. Notably, the Nano‐ant Gel significantly improves the locomotor functions of mice with SCI, suggesting that it represents a promising approach for treating the condition.

Human induced pluripotent stem cell/embryonic stem cell-derived pyramidal neuronal precursors show safety and efficacy in a rat spinal cord injury model

Nerve regeneration and circuit reconstruction remain a challenge following spinal cord injury (SCI). Corticospinal pyramidal neurons possess strong axon projection ability. In this study, human induced pluripotent stem cells (iPSCs) were differentiated into pyramidal neuronal precursors (PNPs) by addition of small molecule dorsomorphin into the culture. iPSC-derived PNPs were transplanted acutely into a rat contusion SCI model on the same day of injury. Following engraftment, the SCI rats showed significantly improved motor functions compared with vehicle control group as revealed by behavioral tests. Eight weeks following engraftment, the PNPs matured into corticospinal pyramidal neurons and extended axons into distant host spinal cord tissues, mostly in a caudal direction. Host neurons rostral to the lesion site also grew axons into the graft. Possible synaptic connections as a bridging relay may have been formed between host and graft-derived neurons, as indicated by pre- and post-synaptic marker staining and the regulation of chemogenetic regulatory systems. PNP graft showed an anti-inflammatory effect at the injury site and could bias microglia/macrophages towards a M2 phenotype. In addition, PNP graft was safe and no tumor formation was detected after transplantation into immunodeficient mice and SCI rats. The potential to reconstruct a neuronal relay circuitry across the lesion site and to modulate the microenvironment in SCI makes PNPs a promising cellular candidate for treatment of SCI.

Epidermal Neural Crest Stem Cell Conditioned Medium Enhances Spinal Cord Injury Recovery via PI3K/AKT-Mediated Neuronal Apoptosis Suppression

This study aimed to assess the impact of conditioned medium from epidermal neural crest stem cells (EPI-NCSCs-CM) on functional recovery following spinal cord injury (SCI), while also exploring the involvement of the PI3K-AKT signaling pathway in regulating neuronal apoptosis. EPI-NCSCs were isolated from 10-day-old Sprague-Dawley rats and cultured for 48 h to obtain EPI-NCSC-CM. SHSY-5Y cells were subjected with H2O2 treatment to induce apoptosis. Cell viability and survival rates were evaluated using the CCK-8 assay and calcein-AM/PI staining. SCI contusion model was established in adult Sprague-Dawley rats to assess functional recovery, utilizing the Basso, Beattie and Bresnahan (BBB) scoring system, inclined test, and footprint observation. Neurological restoration after SCI was analyzed through electrophysiological recordings. Histological analysis included hematoxylin and eosin (H&E) staining and Nissl staining to evaluate tissue organization. Apoptosis and oxidative stress levels were assessed using TUNEL staining and ROS detection methods. Additionally, western blotting was performed to examine the expression of apoptotic markers and proteins related to the PI3K/AKT signaling pathway. EPI-NCSC-CM significantly facilitated functional and histological recovery in SCI rats by inhibiting neuronal apoptosis through modulation of the PI3K/AKT pathway. Administration of EPI-NCSCs-CM alleviated H2O2-induced neurotoxicity in SHSY-5Y cells in vitro. The use of LY294002, a PI3K inhibitor, underscored the crucial role of the PI3K/AKT signaling pathway in regulating neuronal apoptosis. This study contributes to the ongoing exploration of molecular pathways involved in spinal cord injury (SCI) repair, focusing on the therapeutic potential of EPI-NCSC-CM. The research findings indicate that EPI-NCSC-CM exerts a neuroprotective effect by suppressing neuronal apoptosis through activation of the PI3K/AKT pathway in SCI rats. These results highlight the promising role of EPI-NCSC-CM as a potential treatment strategy for SCI, emphasizing the significance of the PI3K/AKT pathway in mediating its beneficial effects.Graphical

Spinal cord lesion MRI and behavioral outcomes in a miniature pig model of spinal cord injury: exploring preclinical potential through an ad hoc comparison with human SCI.

prospective case series of Yucatan miniature pig spinal cord contusion injury model with comparison to human cases of spinal cord injury (SCI). to describe magnetic resonance imaging (MRI) measures of spinal cord lesion severity along with estimates of lateral corticospinal tracts spared neural tissue in both a less severe and more severe contusion SCI model, as well as to describe their corresponding behavioral outcome changes. University laboratory setting. Following a more severe and less severe SCI, each pig underwent spinal cord MRI to measure lesion characteristics, along with locomotor and urodynamics outcomes testing. In the pig with more severe SCI, locomotor and urodynamic outcomes were poor, and both the spinal cord lesion volume and damage estimates to the lateral corticospinal tracts were large. Conversely, in the pig with less severe SCI, locomotor and urodynamic outcomes were favorable, with the spinal cord lesion volume and damage estimates to the lateral corticospinal tracts being less pronounced. For two human cases matched on estimates of damage to the lateral corticospinal tract regions, the clinical presentations were similar to the pig outcomes, with more limited mobility and more limited bladder functional independence in the more severe case. Our initial findings contribute valuable insights to the emergent field of MRI-based evaluation of spinal cord lesions in pig models, offering a promising avenue for understanding and potentially improving outcomes in spinal cord injuries.

Old age alters inflammation and autophagy signaling in the brain, leading to exacerbated neurological outcomes after spinal cord injury in male mice

Older patients with spinal cord injury (SCI) have different features with regard to neurological characteristics after injury. Recent large-scale longitudinal population-based studies showed that individuals with SCI are at a higher risk of developing dementia than non-SCI patients, indicating that SCI is a potential risk factor for dementia. Aging is known to potentiate inflammation and neurodegeneration at the injured site leading to impaired recovery from SCI. However, no research has been aimed at studying the mechanisms of SCI-mediated cognitive impairment in the elderly. The present study examined neurobehavioral and molecular changes in the brain and the underlying mechanisms associated with brain dysfunction in aged C57BL/6 male mice using a contusion SCI model. At 2 months post-injury, aged mice displayed worse performance in locomotor, cognitive and depressive-like behavioral tests compared to young adult animals. Histopathology in injured spinal cord tissue was exacerbated in aged SCI mice. In the brain, transcriptomic analysis with NanoString neuropathology panel identified activated microglia and dysregulated autophagy as the most significantly altered pathways by both age and injury. These findings were further validated by flow cytometry, which demonstrated increased myeloid and lymphocytes infiltration at both the injured site and brain of aged mice. Moreover, SCI in aged mice altered microglial function and dysregulated autophagy in microglia, resulting in worsened neurodegeneration. Taken together, our data indicate that old age exacerbates neuropathological changes in both the injured spinal cord and remote brain regions leading to poorer functional outcomes, at least in part, through altered inflammation and autophagy function.

Characterization of HSP90 expression and function following CNS injury

Spinal cord injury induces significant cellular stress responses. The Heat Shock Protein 90 (HSP90) plays a pivotal role as a molecular chaperone and is crucial for protein folding, stabilization, and cellular signaling pathways. Despite its important function in stress adaptation, the specific expression patterns and functional roles of HSP90 after nerve injury remain unclear. This study aimed to elucidate the expression dynamics and functional implications of HSP90 following central nervous system (CNS) injury. Using western blotting and immunohistochemical analyses, we observed upregulation of HSP90 expression in spinal cord tissues and within injured neurons in a spinal cord contusion injury model. Additionally, HSP90 was found to enhance neurite outgrowth in primary cortical neurons cultured in vitro. Furthermore, in a glutamate-induced neuronal injury model, the expression of HSP90 was up-regulated, and overexpression of HSP90 promoted neurite re-growth in damaged neurons. Overall, our findings highlight the critical involvement of HSP90 in the neural response to injury and offer valuable insights into potential therapeutic strategies for CNS repair.

Exosomes derived from vMIP-II-Lamp2b gene-modified M2 cells provide neuroprotection by targeting the injured spinal cord, inhibiting chemokine signals and modulating microglia/macrophage polarization in mice

Inflammation is one of the key injury factors for spinal cord injury (SCI). Exosomes (Exos) derived from M2 macrophages have been shown to inhibit inflammation and be beneficial in SCI animal models. However, lacking targetability restricts their application prospects. Considering that chemokine receptors increase dramatically after SCI, viral macrophage inflammatory protein II (vMIP-II) is a broad-spectrum chemokine receptor binding peptide, and lysosomal associated membrane protein 2b (Lamp2b) is the key membrane component of Exos, we speculated that vMIP-II-Lamp2b gene-modified M2 macrophage-derived Exos (vMIP-II-Lamp2b-M2-Exo) not only have anti-inflammatory properties, but also can target the injured area by vMIP-II. In this study, using a murine contusive SCI model, we revealed that vMIP-II-Lamp2b-M2-Exo could target the chemokine receptors which highly expressed in the injured spinal cords, inhibit some key chemokine receptor signaling pathways (such as MAPK and Akt), further inhibit proinflammatory factors (such as IL-1β, IL-6, IL-17, IL-18, TNF-α, and iNOS), and promote anti-inflammatory factors (such as IL-4 and Arg1) productions, and the transformation of microglia/macrophages from M1 into M2. Moreover, the improved histological and functional recoveries were also found. Collectively, our results suggest that vMIP-II-Lamp2b-M2-Exo may provide neuroprotection by targeting the injured spinal cord, inhibiting some chemokine signals, reducing proinflammatory factor production and modulating microglia/macrophage polarization.

Neuroprotective properties of plant extract green-formulated silver nanoparticles on the contusive model of spinal cord injury in rats

Silver nanoparticles (Ag NPs) are highly sought-after metal nanoparticles globally due to their distinctive electronic and optical characteristics, as well as their biological properties. These attributes stem from the synchronized movements of conduction electrons, referred to as surface plasmon resonance. Currently, numerous bio-medical characteristics of biosynthesized Ag nanoparticles have been thoroughly documented, including their anti-inflammatory, antioxidant, anticancer, and antimicrobial properties. Nevertheless, there have been no reports regarding the neuroprotective efficacy of these nanoparticles against cytotoxic agents. It appears that the defensive capabilities of the NPs formulated by green methods have been disregarded thus far. We recently did research to assess the neuroprotective effects of a combination of Tribulus terrestris and green-mediated silver nanoparticles on a contusive spinal cord injury model in animals. The silver nanoparticles underwent comprehensive characterization through UV–Vis, FE-SEM, FT-IR, and TEM analyses. In the in vivo phase of the research, a total of forty rats were categorized into three groups: untreated, normal, and silver nanoparticles (50 µg/kg) groups. The post-injury lesions were analyzed using H&E staining. To evaluate the restoration of neural conduction, somatosensory evoked potential testing was conducted. The presence of astrogliosis was determined by evaluating the expression of GFAP. The rats' behavioral outcomes were assessed using the BBB score every week. The utilization of silver nanoparticles demonstrated neuroprotective properties and resulted in enhancements in spinal cord injury. The results of the sensory assessments indicated a notable rise in the Basso, Beattie, and Bresnahan scales, along with a marked decline in delayed reactions, among the subjects who received treatment with silver nanoparticles. The most substantial decrease in GFAP levels was noted in the group that was administered silver nanoparticles. Furthermore, there was a substantial decrease in the size of the cavity regions, while the quantity of ventral motor neurons experienced a significant rise within the silver nanoparticles group. The electromyography (EMG) results demonstrated a remarkable enhancement in the hindlimbs of the subjects who received treatment with silver nanoparticles (50 µg/kg).

Impact of Activity-Based Training on Bowel Function in a Rat Model of Spinal Cord Injury.

Significant bowel-related issues after spinal cord injury (SCI) that affect morbidity and quality of life (QOL) include diminished bowel motility, loss of sphincter control, gastric ulcers, autonomic dysreflexia, pain, diarrhea, constipation, and fecal incontinence. Clinical diagnoses and research in humans have largely relied on anorectal manometry (ARM) procedures to increase understanding of the functional effects of SCI on colorectal motility and defecation physiology. Recent pre-clinical rodent studies have also used ARM to further our understanding of bowel-related dysfunctions post-SCI. In the present study, the benefits of different activity-based training (ABT) durations on bowel function were examined. Six groups of male rats including two non-training (NT; uninjured and SCI) and four ABT (quadrupedal [Quad or Q] stepping on a treadmill) groups. All ABT animals received 4 weeks of 1-h daily stepping beginning 2 weeks post-SCI followed by variable amounts for 4 additional weeks (none; daily; once a week; daily for final 4th week only). Outcome measures included fecal output (home cage; metabolic cage) throughout the study and terminal measurements (post 8-week ABT) of external anal sphincter (EAS) electromyography, resting anorectal pressure, and giant contraction (GC) activation under urethane anesthesia. The results indicate that treadmill training normalized defecation amount based on feces weight and food intake, as well as GC frequency, EAS latency and amplitude during fecal expulsion, and resting pressure in specific areas within the colorectum. The two intermittent training groups consistently showed recorded metrics comparable to the non-injured group. The results demonstrate bowel dysfunction in the rodent SCI contusion model with improvements in functional outcomes following ABT. Importantly, the benefits to bowel-related functions with versus without intermittent ABT illustrate the need for periodic therapy to maintain the functional gains of ABT.

Evaluation of human mononuclear umbilical cord blood cells systemic administration efficiency in the acute period of experimental severe spinal cord injury

Aim. To evaluate the efficiency of systemic (intravenous) application of cryopreserved human umbilical cord blood mononuclear cells (HUCBCs) in animal models of acute contusion spinal cord injury for the restoration of hind limb motor function and formation of posttraumatic cysts using clinically significant examination methods.Materials and methods. Adult female Sprague–Dowley rats were used for the study. Severe acute contusion spinal cord injury model was performed using standard “weight‑drop” method. All samples of cryopreserved HUCBCs concentrate were prestored prior to infusion for 3 to 4 years at –196 °C. Hind limbs motor function was evaluated using open‑field technique and standard BBB testing system. Magnetic resonance scanning was performed using high‑field magnetic resonance CleanScan 7.0 T tomography (Bruker BioSpin, Germany).Results. Intravenous infusions of HUCBCs were performed on Day 1 following acute severe spinal cord injury. Motor function assessment demonstrated significant (p <0.05) improvement of hind limbs motor function (up to 40–50 %) comparing to self‑healing outcomes. Moreover, by the Days 4 and 5 after severe spinal cord injury, the volume of posttraumatic cystic cavity decreases significantly (up to 40 %) (p <0.05).Conclusion. The obtained results demonstrated that cryopreserved HUCBCs can be used as an effective source for cell therapy of acute contusion spinal cord injury.

Automated Impactor for Contusive Spinal Cord Injury Model in Mice.

Spinal cord injury (SCI) due to traumatic injuries such as car accidents and falls is associated with permanent spinal cord dysfunction. Creation of contusion models of spinal cord injury by impacting the spinal cord results in similar pathologies to most spinal cord injuries in clinical practice. Accurate, reproducible, and convenient animal models of spinal cord injury are essential for studying spinal cord injury. We present a novel automated spinal cord injury contusion device for mice, the Guangzhou Jinan University smart spinal cord injury system, that can produce spinal cord injury contusion models with accuracy, reproducibility, and convenience. The system accurately produces models of varying degrees of spinal cord injury via laser distance sensors combined with an automated mobile platform and advanced software. We used this system to create three levels of spinal cord injury mice models, determined their Basso mouse scale (BMS) scores, and performed behavioral as well as staining assays to demonstrate its accuracy and reproducibility. We show each step of the development of the injury models using this device, forming a standardized procedure. This method produces reproducible spinal cord injury contusion mice models and reduces human manipulation factors via convenient handling procedures. The developed animal model is reliable for studying spinal cord injury mechanisms and associated treatment approaches.

Creating a Reproducible Model of Spinal Cord Injury in Rats: A Contusion Approach.

Spinal cord injury (SCI) is a devastating clinical condition that affects millions of people worldwide. SCI primarily affects males in younger age groups. It is characterized by a complex of neurological dysfunctions that can lead to permanent disability. We describe an adapted technique for SCI, i.e., a contusion model of SCI, in this chapter. This model is widely used to study the pathology of SCI and test potential therapies. The experimental contusion is performed by using a compression device, which allows the creation of a reproducible injury animal model through the definition of specific injury parameters. A detailed methodology has been developed and described here that utilizes a stereotactic frame and impactor to produce reproducible injuries.

Contribution of mechanoreceptors to spinal cord injury-induced mechanical allodynia.

Evidence from previous studies supports the concept that spinal cord injury (SCI)-induced neuropathic pain (NP) has its neural roots in the peripheral nervous system. There is uncertainty about how and to which degree mechanoreceptors contribute. Sensorimotor activation-based interventions (eg, treadmill training) have been shown to reduce NP after experimental SCI, suggesting transmission of pain-alleviating signals through mechanoreceptors. The aim of the present study was to understand the contribution of mechanoreceptors with respect to mechanical allodynia in a moderate mouse contusion SCI model. After genetic ablation of tropomyosin receptor kinase B expressing mechanoreceptors before SCI, mechanical allodynia was reduced. The identical genetic ablation after SCI did not yield any change in pain behavior. Peptidergic nociceptor sprouting into lamina III/IV below injury level as a consequence of SCI was not altered by either mechanoreceptor ablation. However, skin-nerve preparations of contusion SCI mice 7 days after injury yielded hyperexcitability in nociceptors, not in mechanoreceptors, which makes a substantial direct contribution of mechanoreceptors to NP maintenance unlikely. Complementing animal data, quantitative sensory testing in human SCI subjects indicated reduced mechanical pain thresholds, whereas the mechanical detection threshold was not altered. Taken together, early mechanoreceptor ablation modulates pain behavior, most likely through indirect mechanisms. Hyperexcitable nociceptors seem to be the main drivers of SCI-induced NP. Future studies need to focus on injury-derived factors triggering early-onset nociceptor hyperexcitability, which could serve as targets for more effective therapeutic interventions.

Implantation of human urine stem cells promotes neural repair in spinal cord injury rats associated cadeharin-1 and integrin subunit beta 1 expression.

The aim of this study was to determine the effect of human urine-derived stem cells (HUSCs) for the treatment of spinal cord injury (SCI) and investigate associated the molecular network mechanism by using bioinformatics combined with experimental validation. After the contusive SCI model was established, the HUSC-expressed specific antigen marker was implanted into the injury site immediately, and the Basso, Beattie and Bresnahan locomotor rating scale (BBB scale) was utilized to evaluate motor function so as to determine the effect of HUSCs for the neural repair after SCI. Then, the geneCards database was used to collect related gene targets for both HUSCs and SCI, and cross genes were merged with the findings of PubMed screen. Subsequently, protein-protein interaction (PPI) network, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment, as well as core network construction, were performed using Cytoscape software. Lastly, real-time quantitative polymerase chain reaction (PCR) and immunofluorescence were employed to validate the mRNA expression and localization of 10 hub genes, and two of the most important, designated as cadherin 1 (CDH1) and integrin subunit beta 1 (ITGB1), were identified successfully. The immunophenotypes of HUSCs were marked by CD90+ and CD44+ but not CD45, and flow cytometry confirmed their character. The expression rates of CD90, CD73, CD44 and CD105 in HUSCs were 99.49, 99.77, 99.82 and 99.51%, respectively, while the expression rates of CD43, CD45, CD11b and HLA-DR were 0.08, 0.30, 1.34 and 0.02%, respectively. After SCI, all rats appeared to have severe motor dysfunction, but the BBB score was increased in HUSC-transplanted rats compared with control rats at 28 days. By using bioinformatics, we obtained 6668 targets for SCI and 1095 targets for HUSCs and identified a total of 645 cross targets between HUSCs and SCI. Based on the PPI and Cytoscape analysis, CD44, ACTB, FN1, ITGB1, HSPA8, CDH1, ALB, HSP90AA1 and GAPDH were identified as possible therapeutic targets. Enrichment analysis revealed that the involved signal pathways included complement and coagulation cascades, lysosome, systemic lupus erythematosus, etc. Lastly, quantificational real-time (qRT)-PCR confirmed the mRNA differential expression of CDH1/ITGB1 after HUSC therapy, and glial fibrillary acidic protein (GFAP) immunofluorescence staining showed that the astrocyte proliferation at the injured site could be reduced significantly after HUSC treatment. We validated that HUSC implantation is effective for the treatment of SCI, and the underlying mechanisms associated with the multiple molecular network. Of these, CDH1 and ITGB1 may be considered as important candidate targets. Those findings therefore provided the crucial evidence for the potential use of HUSCs in SCI treatment in future clinic trials.

Chemogenetic Attenuation of Acute Nociceptive Signaling Enhances Functional Outcomes Following Spinal Cord Injury.

Identifying novel therapeutic approaches to promote recovery of neurological functions following spinal cord injury (SCI) remains a great unmet need. Nociceptive signaling in the acute phase of SCI has been shown to inhibit recovery of locomotor function and promote the development of chronic neuropathic pain. We therefore hypothesized that inhibition of nociceptive signaling in the acute phase of SCI might improve long-term functional outcomes in the chronic phase of injury. To test this hypothesis, we took advantage of a selective strategy utilizing AAV6 to deliver inhibitory (hM4Di) Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) to nociceptors of the L4-L6 dorsal root ganglia to evaluate the effects of transient nociceptor silencing on long-term sensory and motor functional outcomes in a rat thoracic contusion SCI model. Following hM4Di-mediated nociceptor inhibition from 0-14 days post-SCI, we conducted behavioral assessments until 70 days post-SCI, then performed histological assessments of lesion severity and axon plasticity. Our results show highly selective expression of hM4Di within small diameter nociceptors including calcitonin gene-related peptide (CGRP)+ and IB4-binding neurons. Expression of hM4Di in less than 25% of nociceptors was sufficient to increase hindlimb thermal withdrawal latency in naïve rats. Compared with subjects who received AAV-yellow fluorescent protein (YFP; control), subjects who received AAV-hM4Di exhibited attenuated thermal hyperalgesia, greater coordination, and improved hindlimb locomotor function. However, treatment did not impact the development of cold allodynia or mechanical hyperalgesia. Histological assessments of spinal cord tissue suggested trends toward reduced lesion volume, increased neuronal sparing and increased CGRP+ axon sprouting in hM4Di-treated animals. Together, these findings suggest that nociceptor silencing early after SCI may promote beneficial plasticity in the acute phase of injury that can impact long-term functional outcomes, and support previous work highlighting primary nociceptors as possible therapeutic targets for pain management after SCI.

Coordination function index: A novel indicator for assessing hindlimb locomotor recovery in spinal cord injury rats based on catwalk gait parameters

In preclinical studies of spinal cord injury (SCI), behavioral assessments are crucial for evaluating treatment effectiveness. Commonly used methods include Basso, Beattie, Bresnahan (BBB) score and the Louisville swim scale (LSS), relying on subjective observations. The CatWalk automated gait analysis system is also widely used in SCI studies, providing extensive gait parameters from footprints. However, these parameters are often used independently or combined simply without utilizing the vast amount of data provided by CatWalk. Therefore, it is necessary to develop a novel approach encompassing multiple CatWalk parameters for a comprehensive and objective assessment of locomotor function. In this work, we screened 208 CatWalk XT gait parameters and identified 38 suitable for assessing hindlimb motor function recovery in a rat thoracic contusion SCI model. Exploratory factor analysis was used to reveal structural relationships among these parameters. Weighted scores for Coordination effectively differentiated hindlimb motor function levels, termed as the Coordinated Function Index (CFI). CFI showed high reliability, exhibiting high correlations with BBB scores, LSS, and T2WI lesion area. Finally, we simplified CFI based on factor loadings and correlation analysis, obtaining a streamlined version with reliable assessment efficacy. In conclusion, we developed a systematic assessment indicator utilizing multiple CatWalk parameters to objectively evaluate hindlimb motor function recovery in rats after thoracic contusion SCI.

Resveratrol improves the prognosis of rats after spinal cord injury by inhibiting mitogen-activated protein kinases signaling pathway

Spinal cord injury (SCI) is a serious condition that results in irreparable nerve damage and severe loss of motor or sensory function. Resveratrol (3,4′,5-trihy- droxystilbene) is a naturally occurring plant-based polyphenol that has demonstrated powerful antioxidative, anti-inflammatory, and anti-carcinogenic pharmaceutical properties in previous studies. In the central nervous system, it promotes neuronal recovery and protects residual function. However, the role of resveratrol in SCI recovery remains elusive. In this study, the potential mechanisms by which resveratrol affect SCI in rats were assessed by constructing a contusion model of SCI. Resveratrol was intraperitoneally administered to rats. Behavioral scores and electrophysiological examinations were performed to assess functional recovery. After magnetic resonance imaging and staining with hematoxylin and eosin (HE) and Luxor Fast Blue (LFB), tissue recovery was analyzed. Immunofluorescence with NeuN and glial fibrillary acidic protein (GFAP) was employed to evaluate neuronal survival and glial changes. TdT-mediated dUTP nick end labeling (TUNEL) assay was performed to examine apoptotic rates. Moreover, network pharmacology was performed to identify relevant pathways of resveratrol for the treatment of SCI. Lastly, ELISA was performed to detect the expression levels of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and IL-6. Our findings revealed that resveratrol dramatically improved the hindlimb locomotor function and their electrophysiological outcomes. Notably, lesion size was significantly reduced on magnetic resonance imaging. HE and LFB staining exposed increased sparseness of tissue and myelin. GFAP and NeuN immunofluorescence assays at the lesion site determined that resveratrol boosted neuronal survival and attenuated glial cell overgrowth. In addition, resveratrol reduced the density and number of TUNEL-positive cells in rats after injury. Additionally, gene ontology analysis revealed that the enriched differentially expressed protein was associated with the JNK/p38MAPK (c-jun N-terminal kinase/p38 mitogen-activated protein kinase) signaling pathway. Following resveratrol treatment, the expression levels of IL-1β, TNF-α, and IL-6 were decreased. In summary, the administration of resveratrol protects motor function and neuronal survival in rats after SCI. Furthermore, resveratrol exerts an anti-inflammatory effect by blocking the JNK/p38MAPK signaling pathway.

A bi-cortical neuroprosthesis to modulate locomotion after incomplete spinal cord injury.

Neuroprosthetic strategies seek to immediately alleviate deficits and reinstate voluntary control of movement. To facilitate recovery, it is crucial to gain a comprehensive understanding of the mechanisms involved in the return of intentional movement. Nevertheless, the precise relationship between the resurgence of cortical commands and the recovery of locomotion remains somewhat elusive. In the study conducted by Duguay, Bonizzato, Delivet-Mongrain, Fortier-Lebel and Martinez, we introduced a neuroprosthesis designed to deliver precise bi-cortical stimulation in a clinically relevant contusive spinal cord injury model. We conducted experiments in both healthy and spinal cord injured cats, where we fine-tuned the timing, duration, amplitude, and site of stimulation to modulate hindlimb locomotor output. In healthy cats, we observed a wide range of motor programs. However, after spinal cord injury, the induced hindlimb movements became highly stereotyped but were effective in modulating gait and reducing bilateral foot dragging. These results suggest that the neural basis for motor recovery traded off selectivity for effectiveness. Through a series of longitudinal assessments, we found that the restoration of locomotion following spinal cord injury was closely linked to the recovery of the descending neural drive. This underscores the importance of directing rehabilitation interventions toward the cortical target. The study results are discussed in terms of their impact and limitations.