From single to combinatorial therapies in spinal cord injuries for structural and functional restoration

Spinal cord injury results in paralysis, sensory disturbances, sphincter dysfunction, and multiple systemic secondary conditions, most arising from autonomic dysregulation. All this produces profound negative psychosocial implications for affected people, their families, and their communities;the financial costs can be challenging for their families and health institutions. Treatments aimed at restoring the spinal cord after spinal cord injury, which have been tested in animal models or clinical trials, generally seek to counteract one or more of the secondary mechanisms of injury to limit the extent of the initial damage. Most published works on structural/functional restoration in acute and chronic spinal cord injury stages use a single type of treatment: a drug or trophic factor, transplant of a cell type, and implantation of a biomaterial. Despite the significant benefits reported in animal models, when translating these successful therapeutic strategies to humans, the result in clinical trials has been considered of little relevance because the improvement, when present, is usually insufficient. Until now, most studies designed to promote neuroprotection or regeneration at different stages after spinal cord injury have used single treatments. Considering the occurrence of various secondary mechanisms of injury in the acute and sub-acute phases of spinal cord injury, it is reasonable to speculate that more than one therapeutic agent could be required to promote structural and functional restoration of the damaged spinal cord. Treatments that combine several therapeutic agents, targeting different mechanisms of injury, which, when used as a single therapy, have shown some benefits, allow us to assume that they will have synergistic beneficial effects. Thus, this narrative review article aims to summarize current trends in the use of strategies that combine therapeutic agents administered simultaneously or sequentially, seeking structural and functional restoration of the injured spinal cord.

Progress in the generation of spinal cord organoids over the past decade and future perspectives

Spinal cord organoids are three-dimensional tissues derived from stem cells that recapitulate the primary morphological and functional characteristics of the spinal cord in vivo.As emerging bioengineering methods have led to the optimization of cell culture protocols,spinal cord organoids technology has made remarkable advancements in the past decade.Our literature search found that current spinal cord organoids do not only dynamically simulate neural tube formation but also exhibit diverse cytoarchitecture along the dorsal-ventral and rostral-caudal axes.Moreover,fused organoids that integrate motor neurons and other regionally specific organoids exhibit intricate neural circuits that allows for functional assessment.These qualities make spinal cord organoids valuable tools for disease modeling,drug screening,and tissue regeneration.By utilizing this emergent technology,researchers have made significant progress in investigating the pathogenesis and potential therapeutic targets of spinal cord diseases.However,at present,spinal cord organoid technology remains in its infancy and has not been widely applied in translational medicine.Establishment of the next generation of spinal cord organoids will depend on good manufacturing practice standards and needs to focus on diverse cell phenotypes and electrophysiological functionality evaluation.

Pharmacological interventions targeting the microcirculation following traumatic spinal cord injury

Traumatic spinal cord injury is a devastating disorder chara cterized by sensory,motor,and autonomic dysfunction that seve rely compromises an individual's ability to perform activities of daily living.These adve rse outcomes are closely related to the complex mechanism of spinal cord injury,the limited regenerative capacity of central neurons,and the inhibitory environment fo rmed by traumatic injury.Disruption to the microcirculation is an important pathophysiological mechanism of spinal cord injury.A number of therapeutic agents have been shown to improve the injury environment,mitigate secondary damage,and/or promote regeneration and repair.Among them,the spinal cord microcirculation has become an important target for the treatment of spinal cord injury.Drug inte rventions targeting the microcirculation can improve the microenvironment and promote recovery following spinal cord injury.These drugs target the structure and function of the spinal cord microcirculation and are essential for maintaining the normal function of spinal neuro ns,axons,and glial cells.This review discusses the pathophysiological role of spinal cord microcirculation in spinal cord injury,including its structure and histopathological changes.Further,it summarizes the progress of drug therapies targeting the spinal cord mic rocirc ulation after spinal cord injury.

Bromocriptine protects perilesional spinal cord neurons from lipotoxicity after spinal cord injury

Recent studies have revealed that lipid droplets accumulate in neurons after brain injury and evoke lipotoxicity,damaging the neurons.However,how lipids are metabolized by spinal cord neurons after spinal cord injury remains unclear.Herein,we investigated lipid metabolism by spinal cord neurons after spinal cord injury and identified lipid-lowering compounds to treat spinal cord injury.We found that lipid droplets accumulated in perilesional spinal cord neurons after spinal cord injury in mice.Lipid droplet accumulation could be induced by myelin debris in HT22 cells.Myelin debris degradation by phospholipase led to massive free fatty acid production,which increased lipid droplet synthesis,β-oxidation,and oxidative phosphorylation.Excessive oxidative phosphorylation increased reactive oxygen species generation,which led to increased lipid peroxidation and HT22 cell apoptosis.Bromocriptine was identified as a lipid-lowering compound that inhibited phosphorylation of cytosolic phospholipase A2 by reducing the phosphorylation of extracellular signal-regulated kinases 1/2 in the mitogen-activated protein kinase pathway,thereby inhibiting myelin debris degradation by cytosolic phospholipase A2 and alleviating lipid droplet accumulation in myelin debris-treated HT22 cells.Motor function,lipid droplet accumulation in spinal cord neurons and neuronal survival were all improved in bromocriptine-treated mice after spinal cord injury.The results suggest that bromocriptine can protect neurons from lipotoxic damage after spinal cord injury via the extracellular signal-regulated kinases 1/2-cytosolic phospholipase A2 pathway.

A novel mouse model of central cord syndrome

Patients with potential spinal stenosis are susceptible to central cord syndrome induced by blunt trauma.Suitable animal models are helpful for studying the pathogenesis and treatment of such injuries.In this study,we established a mouse model of acute blunt traumatic spinal cord injury by compressing the C6 spinal cord with 5 and 10 g/mm~2 compression weights to simulate cervical central cord syndrome.Behavioral testing confirmed that this model exhibited the characteristics of central cord syndrome because motor function in the front paws was impaired,whereas basic motor and sensory functions of the lower extremities were retained.Hematoxylin-eosin staining showed that the diseased region of the spinal cord in this mouse model was restricted to the gray matter of the central cord,whereas the white matter was rarely affected.Magnetic resonance imaging showed a hypointense signal in the lesion after mild and severe injury.In addition,immunofluorescence staining showed that the degree of nerve tract injury in the spinal cord white matter was mild,and that there was a chronic inflammation reaction.These findings suggest that this mouse model of central cord syndrome can be used as a model for preclinical research,and that gray matter is most vulnerable to injury in central cord syndrome,leading to impaired motor function.

In vivo imaging of the neuronal response to spinal cord injury:a narrative review

Deciphering the neuronal response to injury in the spinal cord is essential for exploring treatment strategies for spinal cord injury(SCI).However,this subject has been neglected in part because appropriate tools are lacking.Emerging in vivo imaging and labeling methods offer great potential for observing dynamic neural processes in the central nervous system in conditions of health and disease.This review first discusses in vivo imaging of the mouse spinal cord with a focus on the latest imaging techniques,and then analyzes the dynamic biological response of spinal cord sensory and motor neurons to SCI.We then summarize and compare the techniques behind these studies and clarify the advantages of in vivo imaging compared with traditional neuroscience examinations.Finally,we identify the challenges and possible solutions for spinal cord neuron imaging.

Awake rabbit model of ischemic spinal cord injury with delayed paraplegia:The role of ambient temperature

Background:Paraplegia after spinal cord ischemia is a devastating condition in the clinic.Here,we develop an awake rabbit model of spinal cord ischemia with delayed paraplegia and explore the influence of ambient temperature on the outcomes after injury.Methods:A total of 47 male rabbits were involved in the present study.Transient spinal cord ischemia was induced by occluding the infrarenal abdominal aorta of awake rabbits at different ambient temperatures.To find the optimal conditions for developing delayed paraplegia,hindlimb motor function after ischemia was evaluated between experiments.Results:The onset and magnitude of ischemic injury varied with the ambient temperature maintained during the peri-i schemia period.More serious spinal cord injury occurred when ischemia was induced at higher temperatures.At 18°C,25-minute ischemia resulted in 74%of rabbits developing delayed paraplegia.At a temperature of 28°C or higher,most of the animals developed acute paraplegia immediately.While at 13°C,rabbits usually regained normal motor function without paraplegia.Conclusion:This awake rabbit model is highly reproducible and will be helpful in future studies of delayed paraplegia after spinal cord ischemia.The ambient temperature must be considered while using this model during investigation of therapeutic interventions.

Passive activity enhances residual control ability in patients with complete spinal cord injury

Patients with complete spinal cord injury retain the potential for volitional muscle activity in muscles located below the spinal injury level.However,because of prolonged inactivity,initial attempts to activate these muscles may not effectively engage any of the remaining neurons in the descending pathway.A previous study unexpectedly found that a brief clinical round of passive activity significantly increased volitional muscle activation,as measured by surface electromyography.In this study,we further explored the effect of passive activity on surface electromyographic signals during volitional control tasks among individuals with complete spinal cord injury.Eleven patients with chronic complete thoracic spinal cord injury were recruited.Surface electromyography data from eight major leg muscles were acquired and compared before and after the passive activity protocol.The results indicated that the passive activity led to an increased number of activated volitional muscles and an increased frequency of activation.Although the cumulative root mean square of surface electromyography amplitude for volitional control of movement showed a slight increase after passive activity,the difference was not statistically significant.These findings suggest that brief passive activity may enhance the ability to initiate volitional muscle activity during surface electromyography tasks and underscore the potential of passive activity for improving residual motor control among patients with motor complete spinal cord injury.

Resident immune responses to spinal cord injury:role of astrocytes and microglia

Spinal cord injury can be traumatic or non-traumatic in origin,with the latter rising in incidence and prevalence with the aging demographics of our society.Moreove r,as the global population ages,individuals with co-existent degenerative spinal pathology comprise a growing number of traumatic spinal cord injury cases,especially involving the cervical spinal cord.This makes recovery and treatment approaches particula rly challenging as age and comorbidities may limit regenerative capacity.For these reasons,it is critical to better understand the complex milieu of spinal cord injury lesion pathobiology and the ensuing inflammatory response.This review discusses microglia-specific purinergic and cytokine signaling pathways,as well as microglial modulation of synaptic stability and plasticity after injury.Further,we evaluate the role of astrocytes in neurotransmission and calcium signaling,as well as their border-forming response to neural lesions.Both the inflammatory and reparative roles of these cells have eluded our complete understanding and remain key therapeutic targets due to their extensive structural and functional roles in the nervous system.Recent advances have shed light on the roles of glia in neurotransmission and reparative injury responses that will change how interventions are directed.Understanding key processes and existing knowledge gaps will allow future research to effectively target these cells and harness their regenerative potential.

Epidemiological and clinical features,treatment status,and economic burden of traumatic spinal cord injury in China:a hospital-based retrospective study

Traumatic spinal cord injury is potentially catastrophic and can lead to permanent disability or even death.China has the largest population of patients with traumatic spinal cord injury.Previous studies of traumatic spinal cord injury in China have mostly been regional in scope;national-level studies have been rare.To the best of our knowledge,no national-level study of treatment status and economic burden has been performed.This retrospective study aimed to examine the epidemiological and clinical features,treatment status,and economic burden of traumatic spinal cord injury in China at the national level.We included 13,465 traumatic spinal cord injury patients who were injured between January 2013 and December 2018 and treated in 30 hospitals in 11 provinces/municipalities representing all geographical divisions of China.Patient epidemiological and clinical features,treatment status,and total and daily costs were recorded.Trends in the percentage of traumatic spinal cord injuries among all hospitalized patients and among patients hospitalized in the orthopedic department and cost of care were assessed by annual percentage change using the Joinpoint Regression Program.The percentage of traumatic spinal cord injuries among all hospitalized patients and among patients hospitalized in the orthopedic department did not significantly change overall(annual percentage change,-0.5%and 2.1%,respectively).A total of 10,053(74.7%)patients underwent surgery.Only 2.8%of patients who underwent surgery did so within 24 hours of injury.A total of 2005(14.9%)patients were treated with high-dose(≥500 mg)methylprednisolone sodium succinate/methylprednisolone(MPSS/MP);615(4.6%)received it within 8 hours.The total cost for acute traumatic spinal cord injury decreased over the study period(-4.7%),while daily cost did not significantly change(1.0%increase).Our findings indicate that public health initiatives should aim at improving hospitals’ability to complete early surgery within 24 hours,which is associated with improved sensorimotor recovery,increasing the awareness rate of clinical guidelines related to high-dose MPSS/MP to reduce the use of the treatment with insufficient evidence.

Screening biomarkers for spinal cord injury using weighted gene co-expression network analysis and machine learning

Immune changes and inflammatory responses have been identified as central events in the pathological process of spinal co rd injury.They can greatly affect nerve regeneration and functional recovery.However,there is still limited understanding of the peripheral immune inflammato ry response in spinal cord inju ry.In this study.we obtained microRNA expression profiles from the peripheral blood of patients with spinal co rd injury using high-throughput sequencing.We also obtained the mRNA expression profile of spinal cord injury patients from the Gene Expression Omnibus(GEO)database(GSE151371).We identified 54 differentially expressed microRNAs and 1656 diffe rentially expressed genes using bioinformatics approaches.Functional enrichment analysis revealed that various common immune and inflammation-related signaling pathways,such as neutrophil extracellular trap formation pathway,T cell receptor signaling pathway,and nuclear factor-κB signal pathway,we re abnormally activated or inhibited in spinal cord inju ry patient samples.We applied an integrated strategy that combines weighted gene co-expression network analysis,LASSO logistic regression,and SVM-RFE algorithm and identified three biomarke rs associated with spinal cord injury:ANO10,BST1,and ZFP36L2.We verified the expression levels and diagnostic perfo rmance of these three genes in the original training dataset and clinical samples through the receiver operating characteristic curve.Quantitative polymerase chain reaction results showed that ANO20 and BST1 mRNA levels were increased and ZFP36L2 mRNA was decreased in the peripheral blood of spinal cord injury patients.We also constructed a small RNA-mRNA interaction network using Cytoscape.Additionally,we evaluated the proportion of 22 types of immune cells in the peripheral blood of spinal co rd injury patients using the CIBERSORT tool.The proportions of naive B cells,plasma cells,monocytes,and neutrophils were increased while the proportions of memory B cells,CD8^(+)T cells,resting natural killer cells,resting dendritic cells,and eosinophils were markedly decreased in spinal cord injury patients increased compared with healthy subjects,and ANO10,BST1 and ZFP26L2we re closely related to the proportion of certain immune cell types.The findings from this study provide new directions for the development of treatment strategies related to immune inflammation in spinal co rd inju ry and suggest that ANO10,BST2,and ZFP36L2 are potential biomarkers for spinal cord injury.The study was registe red in the Chinese Clinical Trial Registry(registration No.ChiCTR2200066985,December 12,2022).

Conditioned medium from human dental pulp stem cells treats spinal cord injury by inhibiting microglial pyroptosis

Human dental pulp stem cell transplantation has been shown to be an effective therapeutic strategy for spinal cord injury.However,whether the human dental pulp stem cell secretome can contribute to functional recovery after spinal cord injury remains unclear.In the present study,we established a rat model of spinal cord injury based on impact injury from a dropped weight and then intraperitoneally injected the rats with conditioned medium from human dental pulp stem cells.We found that the conditioned medium effectively promoted the recovery of sensory and motor functions in rats with spinal cord injury,decreased expression of the microglial pyroptosis markers NLRP3,GSDMD,caspase-1,and interleukin-1β,promoted axonal and myelin regeneration,and inhibited the formation of glial scars.In addition,in a lipopolysaccharide-induced BV2 microglia model,conditioned medium from human dental pulp stem cells protected cells from pyroptosis by inhibiting the NLRP3/caspase-1/interleukin-1βpathway.These results indicate that conditioned medium from human dental pulp stem cells can reduce microglial pyroptosis by inhibiting the NLRP3/caspase-1/interleukin-1βpathway,thereby promoting the recovery of neurological function after spinal cord injury.Therefore,conditioned medium from human dental pulp stem cells may become an alternative therapy for spinal cord injury.

Lupenone improves motor dysfunction in spinal cord injury mice through inhibiting the inflammasome activation and pyroptosis in microglia via the nuclear factor kappa B pathway

Spinal cord injury-induced motor dysfunction is associated with neuroinflammation.Studies have shown that the triterpenoid lupenone,a natural product found in various plants,has a remarkable anti-inflammatory effect in the context of chronic inflammation.However,the effects of lupenone on acute inflammation induced by spinal cord injury remain unknown.In this study,we established an impact-induced mouse model of spinal cord injury,and then treated the injured mice with lupenone(8 mg/kg,twice a day)by intrape ritoneal injection.We also treated BV2 cells with lipopolysaccharide and adenosine5’-triphosphate to simulate the inflammatory response after spinal cord injury.Our res ults showed that lupenone reduced IKBa activation and p65 nuclear translocation,inhibited NLRP3 inflammasome function by modulating nuclear factor kappa B,and enhanced the conve rsion of proinflammatory M1 mic roglial cells into anti-inflammatory M2 microglial cells.Furthermore,lupenone decreased NLRP3 inflammasome activation,NLRP3-induced mic roglial cell polarization,and microglia pyroptosis by inhibiting the nuclear factor kappa B pathway.These findings suggest that lupenone protects against spinal cord injury by inhibiting inflammasomes.

Dual-directional regulation of spinal cord injury and the gut microbiota

There is increasing evidence that the gut microbiota affects the incidence and progression of central nervous system diseases via the brain-gut axis.The spinal cord is a vital important part of the central nervous system;however,the underlying association between spinal cord injury and gut interactions remains unknown.Recent studies suggest that patients with spinal cord injury frequently experience intestinal dysfunction and gut dysbiosis.Alterations in the gut microbiota can cause disruption in the intestinal barrier and trigger neurogenic inflammatory responses which may impede recovery after spinal cord injury.This review summarizes existing clinical and basic research on the relationship between the gut microbiota and spinal cord injury.Our research identified three key points.First,the gut microbiota in patients with spinal cord injury presents a key characteristic and gut dysbiosis may profoundly influence multiple organs and systems in patients with spinal cord injury.Second,following spinal cord injury,weakened intestinal peristalsis,prolonged intestinal transport time,and immune dysfunction of the intestine caused by abnormal autonomic nerve function,as well as frequent antibiotic treatment,may induce gut dysbiosis.Third,the gut microbiota and associated metabolites may act on central neurons and affect recovery after spinal cord injury;cytokines and the Toll-like receptor ligand pathways have been identified as crucial mechanisms in the communication between the gut microbiota and central nervous system.Fecal microbiota transplantation,probiotics,dietary interventions,and other therapies have been shown to serve a neuroprotective role in spinal cord injury by modulating the gut microbiota.Therapies targeting the gut microbiota or associated metabolites are a promising approach to promote functional recovery and improve the complications of spinal cord injury.

Transplantation of fibrin-thrombin encapsulated human induced neural stem cells promotes functional recovery of spinal cord injury rats through modulation of the microenvironment

Recent studies have mostly focused on engraftment of cells at the lesioned spinal cord,with the expectation that differentiated neurons facilitate recovery.Only a few studies have attempted to use transplanted cells and/or biomaterials as major modulators of the spinal cord injury microenvironment.Here,we aimed to investigate the role of microenvironment modulation by cell graft on functional recovery after spinal cord injury.Induced neural stem cells reprogrammed from human peripheral blood mononuclear cells,and/or thrombin plus fibrinogen,were transplanted into the lesion site of an immunosuppressed rat spinal cord injury model.Basso,Beattie and Bresnahan score,electrophysiological function,and immunofluorescence/histological analyses showed that transplantation facilitates motor and electrophysiological function,reduces lesion volume,and promotes axonal neurofilament expression at the lesion core.Examination of the graft and niche components revealed that although the graft only survived for a relatively short period(up to 15 days),it still had a crucial impact on the microenvironment.Altogether,induced neural stem cells and human fibrin reduced the number of infiltrated immune cells,biased microglia towards a regenerative M2 phenotype,and changed the cytokine expression profile at the lesion site.Graft-induced changes of the microenvironment during the acute and subacute stages might have disrupted the inflammatory cascade chain reactions,which may have exerted a long-term impact on the functional recovery of spinal cord injury rats.

The combined application of stem cells and three-dimensional bioprinting scaffolds for the repair of spinal cord injury

Spinal cord injury is considered one of the most difficult injuries to repair and has one of the worst prognoses for injuries to the nervous system.Following surgery,the poor regenerative capacity of nerve cells and the generation of new scars can make it very difficult for the impaired nervous system to restore its neural functionality.Traditional treatments can only alleviate secondary injuries but cannot fundamentally repair the spinal cord.Consequently,there is a critical need to develop new treatments to promote functional repair after spinal cord injury.Over recent years,there have been seve ral developments in the use of stem cell therapy for the treatment of spinal cord injury.Alongside significant developments in the field of tissue engineering,three-dimensional bioprinting technology has become a hot research topic due to its ability to accurately print complex structures.This led to the loading of three-dimensional bioprinting scaffolds which provided precise cell localization.These three-dimensional bioprinting scaffolds co uld repair damaged neural circuits and had the potential to repair the damaged spinal cord.In this review,we discuss the mechanisms underlying simple stem cell therapy,the application of different types of stem cells for the treatment of spinal cord injury,and the different manufa cturing methods for three-dimensional bioprinting scaffolds.In particular,we focus on the development of three-dimensional bioprinting scaffolds for the treatment of spinal cord injury.

Human umbilical cord mesenchymal stem cell-derived exosomes loaded into a composite conduit promote functional recovery after peripheral nerve injury in rats

Complete transverse injury of peripheral nerves is challenging to treat.Exosomes secreted by human umbilical cord mesenchymal stem cells are considered to play an important role in intercellular communication and regulate tissue regeneration.In previous studies,a collagen/hyaluronic acid sponge was shown to provide a suitable regeneration environment for Schwann cell proliferation and to promote axonal regeneration.This three-dimensional(3D)composite conduit contains a collagen/hyaluronic acid inner sponge enclosed in an electrospun hollow poly(lactic-co-glycolic acid)tube.However,whether there is a synergy between the 3D composite conduit and exosomes in the repair of peripheral nerve injury remains unknown.In this study,we tested a comprehensive strategy for repairing long-gap(10 mm)peripheral nerve injury that combined the 3D composite conduit with human umbilical cord mesenchymal stem cell-derived exosomes.Repair effectiveness was evaluated by sciatic functional index,sciatic nerve compound muscle action potential recording,recovery of muscle mass,measuring the cross-sectional area of the muscle fiber,Masson trichrome staining,and transmission electron microscopy of the regenerated nerve in rats.The results showed that transplantation of the 3D composite conduit loaded with human umbilical cord mesenchymal stem cell-derived exosomes promoted peripheral nerve regeneration and restoration of motor function,similar to autograft transplantation.More CD31-positive endothelial cells were observed in the regenerated nerve after transplantation of the loaded conduit than after transplantation of the conduit without exosomes,which may have contributed to the observed increase in axon regeneration and distal nerve reconnection.Therefore,the use of a 3D composite conduit loaded with human umbilical cord mesenchymal stem cell-derived exosomes represents a promising cell-free therapeutic option for the treatment of peripheral nerve injury.

Biochanin A attenuates spinal cord injury in rats during early stages by inhibiting oxidative stress and inflammasome activation

Previous studies have shown that Biochanin A,a flavonoid compound with estrogenic effects,can serve as a neuroprotective agent in the context of cerebral ischemia/reperfusion injury;howeve r,its effect on spinal cord injury is still unclea r. In this study,a rat model of spinal cord injury was established using the heavy o bject impact method,and the rats were then treated with Biochanin A(40 mg/kg) via intrape ritoneal injection for 14 consecutive days.The res ults showed that Biochanin A effectively alleviated spinal cord neuronal injury and spinal co rd tissue injury,reduced inflammation and oxidative stress in spinal cord neuro ns,and reduced apoptosis and pyroptosis.In addition,Biochanin A inhibited the expression of inflammasome-related proteins(ASC,NLRP3,and GSDMD)and the Toll-like receptor 4/nuclear factor-κB pathway,activated the Nrf2/heme oxygenase 1 signaling pathway,and increased the expression of the autophagy markers LC3 Ⅱ,Beclin-1,and P62.Moreove r,the therapeutic effects of Biochanin A on early post-s pinal cord injury were similar to those of methylprednisolone.These findings suggest that Biochanin A protected neurons in the injured spinal cord through the Toll-like receptor 4/nuclear factor κB and Nrf2/heme oxygenase 1 signaling pathways.These findings suggest that Biochanin A can alleviate post-spinal cord injury at an early stage.

The secondary injury cascade after spinal cord injury:an analysis of local cytokine/chemokine regulation

After spinal cord injury,there is an extensive infiltration of immune cells,which exacerbates the injury and leads to further neural degeneration.Therefore,a major aim of current research involves targeting the immune response as a treatment for spinal cord injury.Although much research has been performed analyzing the complex inflammatory process following spinal cord injury,there remain major discrepancies within previous literature regarding the timeline of local cytokine regulation.The objectives of this study were to establish an overview of the timeline of cytokine regulation for 2 weeks after spinal cord injury,identify sexual dimorphisms in terms of cytokine levels,and determine local cytokines that significantly change based on the severity of spinal cord injury.Rats were inflicted with either a mild contusion,moderate contusion,severe contusion,or complete transection,7 mm of spinal cord centered on the injury was harvested at varying times post-injury,and tissue homogenates were analyzed with a Cytokine/Chemokine 27-Plex assay.Results demonstrated pro-inflammatory cytokines including tumor necrosis factorα,interleukin-1β,and interleukin-6 were all upregulated after spinal cord injury,but returned to uninjured levels within approximately 24 hours post-injury,while chemokines including monocyte chemoattractant protein-1 remained upregulated for days post-injury.In contrast,several anti-inflammatory cytokines and growth factors including interleukin-10 and vascular endothelial growth factor were downregulated by 7 days post-injury.After spinal cord injury,tissue inhibitor of metalloproteinase-1,which specifically affects astrocytes involved in glial scar development,increased more than all other cytokines tested,reaching 26.9-fold higher than uninjured rats.After a mild injury,11 cytokines demonstrated sexual dimorphisms;however,after a severe contusion only leptin levels were different between female and male rats.In conclusion,pro-inflammatory cytokines initiate the inflammatory process and return to baseline within hours post-injury,chemokines continue to recruit immune cells for days post-injury,while anti-inflammatory cytokines are downregulated by a week post-injury,and sexual dimorphisms observed after mild injury subsided with more severe injuries.Results from this work define critical chemokines that influence immune cell infiltration and important cytokines involved in glial scar development after spinal cord injury,which are essential for researchers developing treatments targeting secondary damage after spinal cord injury.

Neurophysiological, histological, and behavioral characterization of animal models of distraction spinal cord injury: a systematic review

Distraction spinal cord injury is caused by some degree of distraction or longitudinal tension on the spinal cord and commonly occurs in patients who undergo corrective operation for severe spinal deformity.With the increased degree and duration of distraction,spinal cord injuries become more serious in terms of their neurophysiology,histology,and behavior.Very few studies have been published on the specific characteristics of distraction spinal cord injury.In this study,we systematically review 22 related studies involving animal models of distraction spinal cord injury,focusing particularly on the neurophysiological,histological,and behavioral characteristics of this disease.In addition,we summarize the mechanisms underlying primary and secondary injuries caused by distraction spinal cord injury and clarify the effects of different degrees and durations of distraction on the primary injuries associated with spinal cord injury.We provide new concepts for the establishment of a model of distraction spinal cord injury and related basic research,and provide reference guidelines for the clinical diagnosis and treatment of this disease.