Acute spinal cord injury serum biomarkers in human and rat: a scoping systematic review

STUDY DESIGN

Scoping systematic review.

OBJECTIVES

To summarize the available experimental clinical and animal studies for the identification of all CSF and serum-derived biochemical markers in human and rat SCI models.

SETTING

Tehran, Iran.

METHODS

In this scoping article, we systematically reviewed the electronic databases of PubMed, Scopus, WOS, and CENTRAL to retrieve current literature assessing the levels of different biomarkers in human and rat SCI models.

RESULTS

A total of 19,589 articles were retrieved and 6897 duplicated titles were removed. The remaining 12,692 studies were screened by their title/abstract and 12,636 were removed. The remaining 56 were considered for full-text assessment, and 11 papers did not meet the criteria, and finally, 45 studies were included. 26 studies were human observational studies comprising 1630 patients, and 19 articles studied SCI models in rats, including 832 rats. Upon reviewing the literature, we encountered a remarkable heterogeneity in terms of selected biomarkers, timing, and method of measurement, studied models, extent, and mechanism of injury as well as outcome assessment measures.

CONCLUSIONS

The specific expression and distribution patterns of biomarkers in relation to spinal cord injury (SCI) phases, and their varied concentrations over time, suggest that cerebrospinal fluid (CSF) and blood biomarkers are effective measures for assessing the severity of SCI.

Steroid inhibited Serpina3n expression which was positively correlated with the degrees of spinal cord injury

Aims

The aim of our project was to identify proteins associated with the extent of spinal cord injury (SCI) and subsequent long-term neurological recovery.

Methods

Through proteomic analysis, we identified proteins that are differentially expressed specifically in the acute phase of injury. We analyzed the concentrations of differentially expressed proteins in serum and the injured spinal cord segment by ELISA.

Results

Serpina3n protein expression in the injured spinal cord segment was increased 101-fold at 12 h after severe SCI and 89-fold at 12 h after mild SCI, as determined by LC‒MS/MS. In the mild and severe SCI groups, serum Serpina3n levels began to increase at 12 h and peaked at 24 h. At 12 h, 24 h and 3 d after injury, serum Serpina3n protein levels were significantly correlated with the severity of injury (12 h: r = 0.6034, P = 0.008; 24 h: r = 0.7542, P = 0.0003; 3 d: r = 0.862, P < 0.001). Serum Serpina3n levels at 2 h, 24 h and 3 d post injury were significantly correlated with long-term neurological recovery at 28 d after SCI (2 h: r = -0.5781, P = 0.012; 24 h: r = -0.5912, P = 0.0098; 3 d: r = -0.7792, P < 0.0001). Methylprednisolone treatment would decrease the serum Serpina3n levels in mice with mild and severe SCI compared with those in placebo-group mice at 12 h and 24 h after SCI. The serum Serpina3n concentration in the severe SCI group was significantly reduced on the third day after steroid treatment.

Conclusion

Taken together, these data suggest that serpina3n may be a circulating biomarker of acute SCI and may be closely associated with injury severity and long-term motor function recovery.

The Accuracy of the S100B Protein Biomarker in the Prognosis of Patients with Acute Spinal Cord Injury

Introduction  The role of some biomarkers such as S100 beta (S100B) has been somewhat known in determining the severity of primary acute spinal cord injury (SCI), and today, it has been the basis of various relevant studies. Therefore, this study estimates the S100B level in serum and cerebrospinal fluid (CSF) in patients with spinal injuries. Methods  This was a descriptive-analytic study. In this study, 31 patients with acute SCI referred to Sari Imam Khomeini Hospital, Iran, were recruited. Patients were divided into two groups of complete and incomplete SCI according to the American Spinal Injury Association (ASIA). The S100B concentrations in serum and CSF levels were compared between the two groups. Result  There was only significant positive correlation between S100B CSF concentration and complete SCI based on the ASIA criterion, meaning that in cases of complete SCI the S100B CSF concentration was significantly increased correlation coefficient (CC) (cc = 0.529 and p  = 0.002). Based on the results of serum S100B protein concentration, 14.70 ng/dL with a sensitivity of 66.7% and specificity of 55% was determined as cutoff for complete SCI. Also, about the CSF S100B protein level variable, concentration of 342.18 ng/dL with 100% sensitivity and 64% specificity was determined as cutoff for complete injury. Conclusion  The results of this unique study have shown that S100B were useful markers for predicting the prognosis of patients with acute SCI and cutoff points determined for serum and especially CSF concentrations can differentiate complete and incomplete SCI.

Profiling Immunological Phenotypes in Individuals During the First Year After Traumatic Spinal Cord Injury: A Longitudinal Analysis

Abstract Individuals with SCI are severely affected by immune system changes, resulting in increased risk of infections and persistent systemic inflammation. While recent data support that immunological changes after SCI differ in the acute and chronic phases of living with SCI, only limited immunological phenotyping in humans is available. To characterize dynamic molecular and cellular immune phenotypes over the first year, we assess RNA (bulk-RNA sequencing), protein, and flow cytometry (FACS) profiles of blood samples from 12 individuals with SCI at 0-3 days and at 3, 6, and 12 months post injury (MPI) compared to 23 uninjured individuals (controls). We identified 967 differentially expressed (DE) genes in individuals with SCI (FDR <0.001) compared to controls. Within the first 6 MPI we detected a reduced expression of NK cell genes, consistent with reduced frequencies of CD56bright, CD56dim NK cells present at 12 MPI. Over 6MPI, we observed increased and prolonged expression of genes associated with inflammation (e.g. HMGB1, Toll-like receptor signaling) and expanded frequencies of monocytes acutely. Canonical T-cell related DE genes (e.g. FOXP3, TCF7, CD4) were upregulated during the first 6 MPI and increased frequencies of activated T cells at 3-12 MPI. Neurological injury severity was reflected in distinct whole blood gene expression profiles at any time after SCI, verifying a persistent 'neurogenic' imprint. Overall, 2876 DE genes emerge when comparing motor complete to motor incomplete SCI (ANOVA, FDR <0.05), including those related to neutrophils, inflammation, and infection. In summary, we identify a dynamic immunological phenotype in humans, including molecular and cellular changes which may provide potential targets to reduce inflammation, improve immunity, or serve as candidate biomarkers of injury severity.

A future blood test for acute traumatic spinal cord injury

Acute spinal cord injury (SCI) requires prompt diagnosis and intervention to minimize the risk of permanent neurologic deficit. Presently, SCI diagnosis and interventional planning rely on magnetic resonance imaging (MRI), which is not always available or feasible for severely injured patients. Detection of disease-specific biomarkers in biofluids via liquid biopsy may provide a more accessible and objective means of evaluating patients with suspected SCI. Cell-free DNA, which has been used for diagnosing and monitoring oncologic disease, may detect damage to spinal cord neurons via tissue-specific methylation patterns. Other types of biomarkers, including proteins and RNA species, have also been found to reflect neuronal injury and may be included as part of a multi-analyte assay to improve liquid biopsy performance. The feasibility of implementing liquid biopsy into current practices of SCI management is supported by the relative ease of blood sample collection as well as recent advancements in droplet digital polymerase chain reaction technology. In this review, we detail the current landscape of biofluid biomarkers for acute SCI and propose a framework for the incorporation of a putative blood test into the clinical management of SCI.

Dynamics of biomarkers across the stages of traumatic spinal cord injury - implications for neural plasticity and repair

BACKGROUND

Traumatic spinal cord injury (SCI) is a complex medical condition causing significant physical disability and psychological distress. While the adult spinal cord is characterized by poor regenerative potential, some recovery of neurological function is still possible through activation of neural plasticity mechanisms. We still have limited knowledge about the activation of these mechanisms in the different stages after human SCI.

OBJECTIVE

In this review, we discuss the potential role of biomarkers of SCI as indicators of the plasticity mechanisms at work during the different phases of SCI.

METHODS

An extensive review of literature related to SCI pathophysiology, neural plasticity and humoral biomarkers was conducted by consulting the PubMed database. Research and review articles from SCI animal models and SCI clinical trials published in English until January 2021 were reviewed. The selection of candidates for humoral biomarkers of plasticity after SCI was based on the following criteria: 1) strong evidence supporting involvement in neural plasticity (mandatory); 2) evidence supporting altered expression after SCI (optional).

RESULTS

Based on selected findings, we identified two main groups of potential humoral biomarkers of neural plasticity after SCI: 1) neurotrophic factors including: Brain derived neurotrophic factor (BDNF), Nerve growth factor (NGF), Neurotrofin-3 (NT-3), and Insulin-like growth factor 1 (IGF-1); 2) other factors including: Tumor necrosis factor-alpha (TNF-α), Matrix Metalloproteinases (MMPs), and MicroRNAs (miRNAs). Plasticity changes associated with these biomarkers often can be both adaptive (promoting functional improvement) and maladaptive. This dual role seems to be influenced by their concentrations and time-window during SCI.

CONCLUSIONS

Further studies of dynamics of biomarkers across the stages of SCI are necessary to elucidate the way in which they reflect the remodeling of neural pathways. A better knowledge about the mechanisms underlying plasticity could guide the selection of more appropriate therapeutic strategies to enhance positive spinal network reorganization.

SCING-Spinal Cord Injury Neuroprotection with Glyburide: a pilot, open-label, multicentre, prospective evaluation of oral glyburide in patients with acute traumatic spinal cord injury in the USA

INTRODUCTION

Acute traumatic spinal cord injury (tSCI) is a devastating neurological disorder with no pharmacological neuroprotective strategy proven effective to date. Progressive haemorrhagic necrosis (PHN) represents an increasingly well-characterised mechanism of secondary injury after tSCI that negatively impacts neurological outcomes following acute tSCI. Preclinical studies evaluating the use of the Food and Drug Administration-approved sulfonylurea receptor 1-transient receptor potential melastatin 4 channel blocker glyburide in rodent models have shown reduced secondary microhaemorrhage formation and the absence of capillary fragmentation, the pathological hallmark of PHN.

METHODS AND ANALYSIS

In this initial phase multicentre open-label pilot study, we propose to enrol 10 patients with acute cervical tSCI to primarily assess the feasibility, and safety of receiving oral glyburide within 8 hours of injury. Secondary objectives include pharmacokinetics and preliminary evaluations on neurological recovery as well as blood and MRI-based injury biomarkers. Analysis will be performed using the descriptive and non-parametric statistics.

ETHICS AND DISSEMINATION

Glyburide has been shown as an effective neuroprotective agent in preclinical tSCI models and in the treatment of ischaemic stroke with the additional risk of a hypoglycaemic response. Given the ongoing secondary injury and the traumatic hyperglycaemic stress response seen in patients with tSCI, glyburide; thus, offers an appealing neuroprotective strategy to supplement standard of care treatment. The study protocol was approved by the Ohio State University Biomedical Institutional Review Board. The protocol was amended in February 2017 with changes related to study feasibility and patient recruitment. Specifically, the route of administration was changed to the oral form to allow for streamlined and rapid drug administration, and the injury-to-drug time window was extended to 8 hours in an effort to further enhance enrolment. Participants or legally authorised representatives are informed about the trial and its anticipated risks orally and in written form using an approved informed consent form prior to inclusion. The findings of this study will be disseminated to the participants and to academic peers through scientific conferences and peer-reviewed journal publications.

TRIAL REGISTRATION NUMBERS

NCT02524379 and 2014H0335.

The Value of MicroRNAs as an Indicator of the Severity and the Acute Phase of Spinal Cord Injury

Objective

To assess the role of miRNA-21 and miRNA-223 in a balloon-compression model of spinal cord injury (SCI).

Methods

A total of 50 male Wistar rats (n=50) were divided into the three groups: the group A (n=15, insertion of the unflated Fogarty balloon catheter), the group B (n=15, insertion of the Fogarty balloon catheter at a volume of 20 μL) and the group C (n=15, insertion of the Fogarty balloon catheter at a volume of 50 μL). After the behavioral test, RNA isolation, microRNA expression profiling using microarrays and quantitative polymerase chain reaction, measurements were compared between the three groups.

Results

Despite a lack of significant differences in time-dependent changes in miRNA-21 expression levels between the three groups at 4 hours, there were significant differences in them at 1, 3, and 7 days (p<0.05). Moreover, there were significant differences in time-dependent changes in miRNA-223 expression levels between the three groups at 4 hours and 1, 3, and 7 days (p<0.05). Furthermore, miRNA-223 expression levels reached the highest at 1 day but were decreased with time thereafter in all the three groups.

Conclusion

Expression levels of miRNA-21 and miRNA-223 might be associated with the severity and acute phase of SCI, respectively. It is mandatory, however, to analyze changes in levels of inflammatory markers and the relevant biological pathways.

MicroRNA Biomarkers in Cerebrospinal Fluid and Serum Reflect Injury Severity in Human Acute Traumatic Spinal Cord Injury

Spinal cord injury (SCI) is a devastating condition with variability in injury mechanisms and neurologic recovery. Spinal cord impairment after SCI is measured and classified by a widely accepted standard neurological examination. In the very acute stages post-injury, however, this examination is extremely challenging (and often impossible) to conduct and has modest prognostic value in terms of neurological recovery. The lack of objective tools to classify injury severity and predict outcome is a barrier for clinical trials and thwarts development of therapies for those with SCI. Biological markers (biomarkers) represent a promising, complementary approach to these challenges because they represent an unbiased approach to classify injury severity and predict neurological outcome. Identification of a suitable panel of molecular biomarkers would comprise a fundamental shift in how patients with acute SCI are evaluated, stratified, and treated in clinical trials. MicroRNA are attractive biomarker candidates in neurological disorders for several reasons, including their stability in biological fluids, their conservation between humans and model mammals, and their tissue specificity. In this study, we used next-generation sequencing to identify microRNA associated with injury severity within the cerebrospinal fluid (CSF) and serum of human patients with acute SCI. The CSF and serum samples were obtained 1-5 days post-injury from 39 patients with acute SCI (24 American Spinal Injury Association Impairment Scale [AIS] A, 8 AIS B, 7 AIS C) and from five non-SCI controls. We identified a severity-dependent pattern of change in microRNA expression in CSF and identified a set of microRNA that are diagnostic of baseline AIS classification and prognostic of neurological outcome six months post-injury. The data presented here provide a comprehensive description of the CSF and serum microRNA expression changes that occur after acute human SCI. This data set reveals microRNA candidates that warrant further evaluation as biomarkers of injury severity after SCI and as key regulators in other neurological disorders.

Nanovector-Mediated Drug Delivery in Spinal Cord Injury: A Multitarget Approach

Many preclinical studies seek cures for spinal cord injury (SCI), but when the results are translated to clinical trials they give scant efficacy. One possible reason is that most strategies use treatments directed toward a single pathological mechanism, while a multitherapeutic approach needs to be tested to significantly improve outcomes after SCI. Most of the preclinical reports gave better outcomes when a combination of different compounds was used instead of a single drug. This promising approach, however, must still be improved because it raises some criticism: (i) the blood-spinal cord barrier limits drug distribution, (ii) it is hard to understand the interactions among the pharmacological components after systemic administration, and (iii) the timing of treatments is crucial: the spread of the lesion is a process finely regulated over time, so therapies must be scheduled at precise times during the postinjury course. Nanomedicine could be useful to overcome these limitations. Nanotools allow finely regulated drug administration in terms of cell selectivity and release kinetics. We believe that excellent therapeutic results could be obtained by exploiting this tool in multitherapy. Combining nanoparticles loaded with different compounds that act on the main pathological pathways could overcome the restrictions of traditional drug delivery routes, a major limit for the clinical application of multitherapy. This review digs into these topics, discussing the critical aspects of multitherapies now proposed and suggesting new points of view.

Time course and prognostic value of serum GFAP, pNFH, and S100β concentrations in dogs with complete spinal cord injury because of intervertebral disc extrusion

Background

A noninvasive biomarker is needed to predict recovery from severe spinal cord injury (SCI) because of thoracolumbar intervertebral disc extrusion (TL‐IVDE). Proteins released from neural and glial cells can be detected in the blood and show promise as prognostic tools, but their concentration is influenced by time after injury.

Hypothesis/Objectives

Serum concentrations of glial fibrillary acidic protein (GFAP), phosphorylated neurofilament heavy chain (pNFH), and S100β will follow different time courses; measurement of combinations of these proteins will predict outcome.

Animals

Thirty‐one dogs with TL‐IVDE causing paralysis with no pain perception.

Methods

Prospective study. Serum samples were taken at presentation and intervals over 56 days and banked at −80°C. Glial fibrillary acidic protein, pNFH, and S100β concentrations were measured using ELISA tests and plotted against time from onset of nonambulatory status. Outcome was established at 6 months. The association between biomarker concentration and outcome was examined using logistic regression, receiver operator characteristics curve analysis, and model development.

Results

Thirty‐one dogs participated, 3/31 (10%) developed progressive myelomalacia and 19/31 (62%) recovered ambulation. Glial fibrillary acidic protein and S100β concentrations rose for the first 1 to 3 days, and were undetectable by 14 and 28 days, respectively. Phosphorylated neurofilament heavy chain concentrations peaked at 14 days and were detectable at 56 days. Glial fibrillary acidic protein concentrations in the first 72 hours after onset of nonambulatory status predicted recovery with an accuracy of 76.7%‐89% depending on sample timing.

Conclusions and Clinical Importance

Serum GFAP concentrations can be used to predict outcome in clinically complete SCI. A rapid inexpensive bedside test is needed.

Biomarkers in Spinal Cord Injury: Prognostic Insights and Future Potentials

Spinal Cord Injury (SCI) is a major challenge in Neurotrauma research. Complex pathophysiological processes take place immediately after the injury and later on as the chronic injury develops. Moreover, SCI is usually accompanied by traumatic injuries because the most common modality of injury is road traffic accidents and falls. Patients develop significant permanent neurological deficits that depend on the extent and the location of the injury itself and in time they develop further neurological and body changes that may risk their mere survival. In our review, we explored the recent updates with regards to SCI biomarkers. We observed two methods that may lead to the appearance of biomarkers for SCI. First, during the first few weeks following the injury the Blood Spinal Cord Barrier (BSCB) disruption that releases several neurologic structure components from the injured tissue. These components find their way to Cerebrospinal Fluid (CSF) and the systemic circulation. Also, as the injury develops several components of the pathological process are expressed or released such as in neuroinflammation, apoptosis, reactive oxygen species, and excitotoxicity sequences. Therefore, there is a growing interest in examining any correlations between these components and the degrees or the outcomes of the injury. Additionally, some of the candidate biomarkers are theorized to track the progressive changes of SCI which offers an insight on the patients' prognoses, potential-treatments-outcomes assessment, and monitoring the progression of the complications of chronic SCI such as Pressure Ulcers and urinary dysfunction. An extensive literature review was performed covering literature, published in English, until February 2018 using the Medline/PubMed database. Experimental and human studies were included and titles, PMID, publication year, authors, biomarkers studies, the method of validation, relationship to SCI pathophysiology, and concluded correlation were reported. Potential SCI biomarkers need further validation using clinical studies. The selection of the appropriate biomarker group should be made based on the stage of the injuries, the accompanying trauma and with regards to any surgical, or medical interference that might have been done. Additionally, we suggest testing multiple biomarkers related to the several pathological changes coinciding to offer a more precise prediction of the outcome.

Serum MicroRNAs Reflect Injury Severity in a Large Animal Model of Thoracic Spinal Cord Injury

Therapeutic development for spinal cord injury is hindered by the difficulty in conducting clinical trials, which to date have relied solely on functional outcome measures for patient enrollment, stratification, and evaluation. Biological biomarkers that accurately classify injury severity and predict neurologic outcome would represent a paradigm shift in the way spinal cord injury clinical trials could be conducted. MicroRNAs have emerged as attractive biomarker candidates due to their stability in biological fluids, their phylogenetic similarities, and their tissue specificity. Here we characterized a porcine model of spinal cord injury using a combined behavioural, histological, and molecular approach. We performed next-generation sequencing on microRNAs in serum samples collected before injury and then at 1, 3, and 5 days post injury. We identified 58, 21, 9, and 7 altered miRNA after severe, moderate, and mild spinal cord injury, and SHAM surgery, respectively. These data were combined with behavioural and histological analysis. Overall miRNA expression at 1 and 3 days post injury strongly correlates with outcome measures at 12 weeks post injury. The data presented here indicate that serum miRNAs are promising candidates as biomarkers for the evaluation of injury severity for spinal cord injury or other forms of traumatic, acute, neurologic injury.

Methotrexate combined with methylprednisolone for the recovery of motor function and differential gene expression in rats with spinal cord injury

Methylprednisolone is a commonly used drug for the treatment of spinal cord injury, but high doses of methylprednisolone can increase the incidence of infectious diseases. Methotrexate has anti-inflammatory activity and immunosuppressive effects, and can reduce inflammation after spinal cord injury. To analyze gene expression changes and the molecular mechanism of methotrexate combined with methylprednisolone in the treatment of spinal cord injury, a rat model of spinal cord contusion was prepared using the PinPoint™ precision cortical impactor technique. Rats were injected with methylprednisolone 30 mg/kg 30 minutes after injury, and then subcutaneously injected with 0.3 mg/kg methotrexate 1 day after injury, once a day, for 2 weeks. TreadScan gait analysis found that at 4 and 8 weeks after injury, methotrexate combined with methylprednisolone significantly improved hind limb swing time, stride time, minimum longitudinal deviation, instant speed, footprint area and regularity index. Solexa high-throughput sequencing was used to analyze differential gene expression. Compared with methylprednisolone alone, differential expression of 316 genes was detected in injured spinal cord treated with methotrexate and methylprednisolone. The 275 up-regulated genes were mainly related to nerve recovery, anti-oxidative, anti-inflammatory and anti-apoptotic functions, while 41 down-regulated genes were mainly related to proinflammatory and pro-apoptotic functions. These results indicate that methotrexate combined with methylprednisolone exhibited better effects on inhibiting the activity of inflammatory cytokines and enhancing antioxidant and anti-apoptotic effects and thereby produced stronger neuroprotective effects than methotrexate alone. The 316 differentially expressed genes play an important role in the above processes.

High-Mobility Group Box 1 (HMGB1) Is Elevated Systemically in Persons with Acute or Chronic Traumatic Spinal Cord Injury

Inflammation in traumatic spinal cord injury (SCI) has been proposed to promote damage acutely and oppose functional recovery chronically. However, we do not yet understand the signals that initiate or prolong inflammation in persons with SCI. High-Mobility Group Box 1 (HMGB1) is a potent systemic inflammatory cytokine-or damage-associated molecular pattern molecule (DAMP)-studied in a variety of clinical settings. It is elevated in pre-clinical models of traumatic spinal cord injury (SCI), where it promotes secondary injury, and strategies that block HMGB1 improve functional recovery. To investigate the potential translational relevance of these observations, we measured HMGB1 in plasma from adults with acute (≤ 1 week post-SCI, n = 16) or chronic (≥ 1 year post-SCI, n = 47) SCI. Plasma from uninjured persons (n = 51) served as controls for comparison. In persons with acute SCI, average HMGB1 levels were significantly elevated within 0-3 days post-injury (6.00 ± 1.8 ng/mL, mean ± standard error of the mean [SEM]) or 4-7 (6.26 ± 1.3 ng/mL, mean ± SEM), compared with controls (1.26 ± 0.24 ng/mL, mean ± SEM; p ≤ 0.001 and p ≤ 0.01, respectively). In persons with chronic SCI who were injured for 15 ± 1.5 years (mean ± SEM), HMGB1 also was significantly elevated, compared with uninjured persons (3.7 ± 0.69 vs. 1.26 ± 0.24 ng/mL, mean ± SEM; p ≤ 0.0001). Together, these data suggest that HMGB1 may be a common, early, and persistent danger signal promoting inflammation in individuals with SCI.

Biomarkers in spinal cord compression Ethics and perspectives

The phosphorylated form of the high-molecular-weight neurofilament subunit NF-H (pNF-H) in serum or in cerebro-spinal fluid (CSF) is a specific lesional biomarker for spinal cord injury. The lesional biomarkers and the reaction biomarkers are both presented after several hours post-injury. The specific predictive patterns of lesional biomarkers could be used to aid clinicians with making a diagnosis and establishing a prognosis, and evaluating therapeutic interventions. Diagnosis, prognosis, and treatment guidance based on biomarker used as a predictive indicator can determine ethical difficulties by differentiated therapies in patients with spinal cord compression. At this point based on studies until today we cannot take a decision based on biomarker limiting the treatment of neurological recovery in patients with complete spinal cord injury because we do not know the complexity of the biological response to spinal cord compression.

Cerebrospinal Fluid Biomarkers To Stratify Injury Severity and Predict Outcome in Human Traumatic Spinal Cord Injury

Neurologic impairment after spinal cord injury (SCI) is currently measured and classified by functional examination. Biological markers that objectively classify injury severity and predict outcome would greatly facilitate efforts to evaluate acute SCI therapies. The purpose of this study was to determine how well inflammatory and structural proteins within the cerebrospinal fluid (CSF) of acute traumatic SCI patients predicted American Spinal Injury Association Impairment Scale (AIS) grade conversion and motor score improvement over 6 months. Fifty acute SCI patients (29 AIS A, 9 AIS B, 12 AIS C; 32 cervical, 18 thoracic) were enrolled and CSF obtained through lumbar intrathecal catheters to analyze interleukin (IL)-6, IL-8, monocyte chemotactic protein (MCP)-1, tau, S100β, and glial fibrillary acidic protein (GFAP) at 24 h post-injury. The levels of IL-6, tau, S100β, and GFAP were significantly different between patients with baseline AIS grades of A, B, or C. The levels of all proteins (IL-6, IL-8, MCP-1, tau, S100β, and GFAP) were significantly different between those who improved an AIS grade over 6 months and those who did not improve. Linear discriminant analysis modeling was 83% accurate in predicting AIS conversion. For AIS A patients, the concentrations of proteins such as IL-6 and S100β correlated with conversion to AIS B or C. Motor score improvement also was strongly correlated with the 24-h post-injury CSF levels of all six biomarkers. The analysis of CSF can provide valuable biological information about injury severity and recovery potential after acute SCI. Such biological markers may be valuable tools for stratifying individuals in acute clinical trials where variability in spontaneous recovery requires large recruitment cohorts for sufficient power.

Differential Neuroproteomic and Systems Biology Analysis of Spinal Cord Injury

Acute spinal cord injury (SCI) is a devastating condition with many consequences and no known effective treatment. Although it is quite easy to diagnose traumatic SCI, the assessment of injury severity and projection of disease progression or recovery are often challenging, as no consensus biomarkers have been clearly identified. Here rats were subjected to experimental moderate or severe thoracic SCI. At 24h and 7d postinjury, spinal cord segment caudal to injury center versus sham samples was harvested and subjected to differential proteomic analysis. Cationic/anionic-exchange chromatography, followed by 1D polyacrylamide gel electrophoresis, was used to reduce protein complexity. A reverse phase liquid chromatography-tandem mass spectrometry proteomic platform was then utilized to identify proteome changes associated with SCI. Twenty-two and 22 proteins were up-regulated at 24 h and 7 day after SCI, respectively; whereas 19 and 16 proteins are down-regulated at 24 h and 7 day after SCI, respectively, when compared with sham control. A subset of 12 proteins were identified as candidate SCI biomarkers - TF (Transferrin), FASN (Fatty acid synthase), NME1 (Nucleoside diphosphate kinase 1), STMN1 (Stathmin 1), EEF2 (Eukaryotic translation elongation factor 2), CTSD (Cathepsin D), ANXA1 (Annexin A1), ANXA2 (Annexin A2), PGM1 (Phosphoglucomutase 1), PEA15 (Phosphoprotein enriched in astrocytes 15), GOT2 (Glutamic-oxaloacetic transaminase 2), and TPI-1 (Triosephosphate isomerase 1), data are available via ProteomeXchange with identifier PXD003473. In addition, Transferrin, Cathepsin D, and TPI-1 and PEA15 were further verified in rat spinal cord tissue and/or CSF samples after SCI and in human CSF samples from moderate/severe SCI patients. Lastly, a systems biology approach was utilized to determine the critical biochemical pathways and interactome in the pathogenesis of SCI. Thus, SCI candidate biomarkers identified can be used to correlate with disease progression or to identify potential SCI therapeutic targets.

New approach based on biomarkers in acute traumatic spinal cord injury

Spinal cord injury (SCI) is one of the most devastating traumas for an individual because the complete traumatic spinal cord injury leads to paraplegia or tetraplegia. The mechanical injuries directly cause axonal destruction in fiber tracts, destruction of the neurons and of the glial cells, and their destruction releases substances whose presence, quantity and dynamics can be lesional biomarkers. The reactions of partially injured cells simultaneously start and the occurring substances and their quantity may be reaction biomarkers. The lesional biomarkers appear immediately postinjury and after several hours there are both lesional biomarkers and reaction biomarkers. The most important lesional biomarkers are the phosphorylated neurofilament subunits resulting from the axonal neurofilament destruction. The heavy phosphorylated neurofilament subunit (pNF-H) is a predictive lesional biomarker because its values pattern can show the reducing or stopping of the secondary lesions and the favorable outcome. The complete SCI patients with a favorable development had a specific pattern of daily values of pNF-H: a sudden increase up to a maximum value then a progressive decrease to normal. The patients with unfavorable outcome or neurological stabilisation had two patterns: an increase to a plateau of pNF-H values or a progressive increase up to a peak followed by a progressive decrease to quasi-normal values.

sCD95L in serum after spinal cord injury

STUDY DESIGN

A prospective observational study reporting correlation between sCD95L (serum cluster of differentiation 95 ligand) serum levels and remission after traumatic spinal cord injury (SCI).

OBJECTIVES

To describe the correlation between sCD95L serum levels and remission after traumatic SCI in a human protocol compared with animal studies.

SETTING

Rhineland-Palatinate (Rheinland-Pfalz), Germany.

METHODS

We included 45 patients with traumatic SCI. According to their neurological outcome, patients were divided into two groups, patients with (G1, n=26) and without (G2, n=19) remission. Blood was collected on post-admission and according to a fixed scheme, that is, after 4, 9, 12 h, 1, 3 days and 1, 2, 4, 8, 12 weeks.

RESULTS

By comparing G1 with G2, we found a correlation between neurological remission and sCD95L serum concentrations. Consistently elevated levels of sCD95L in G1 between 9 h and 1 month after injury show significantly differing values 7 days after injury. This indicates a correlation between patients with clinically documented neurological remission and elevated sCD95L serum concentrations.

CONCLUSIONS

In opposite to animal studies, our patients with neurological remission show on average higher levels of sCD95L compared with patients without. Therefore, spinal cord-injured patients would probably not profit from neutralizing CD95L. Our results present that the transfer of findings from animal studies to humans must always be considered critically. We were able to show that peripheral serum cytokine expression is suitable to state processes after SCI in humans.

Traumatically injured astrocytes release a proteomic signature modulated by STAT3-dependent cell survival

Molecular markers associated with CNS injury are of diagnostic interest. Mechanical trauma generates cellular deformation associated with membrane permeability with unknown molecular consequences. We used an in vitro model of stretch-injury and proteomic analyses to determine protein changes in murine astrocytes and their surrounding fluids. Abrupt pressure-pulse stretching resulted in the rapid release of 59 astrocytic proteins with profiles reflecting cell injury and cell death, i.e., mechanoporation and cell lysis. This acute trauma-release proteome was overrepresented with metabolic proteins compared with the uninjured cellular proteome, bearing relevance for post-traumatic metabolic depression. Astrocyte-specific deletion of signal transducer and activator of transcription 3 (STAT3-CKO) resulted in reduced stretch-injury tolerance, elevated necrosis and increased protein release. Consistent with more lysed cells, more protein complexes, nuclear and transport proteins were released from STAT3-CKO versus nontransgenic astrocytes. STAT3-CKO astrocytes had reduced basal expression of GFAP, lactate dehydrogenase B (LDHB), aldolase C (ALDOC), and astrocytic phosphoprotein 15 (PEA15), and elevated levels of tropomyosin (TPM4) and α actinin 4 (ACTN4). Stretching caused STAT3-dependent cellular depletion of PEA15 and GFAP, and its filament disassembly in subpopulations of injured astrocytes. PEA15 and ALDOC signals were low in injured astrocytes acutely after mouse spinal cord crush injury and were robustly expressed in reactive astrocytes 1 day postinjury. In contrast, α crystallin (CRYAB) was present in acutely injured astrocytes, and absent from uninjured and reactive astrocytes, demonstrating novel marker differences among postinjury astrocytes. These findings reveal a proteomic signature of traumatically-injured astrocytes reflecting STAT3-dependent cellular survival with potential diagnostic value.

Development and validation of a microfluidic immunoassay capable of multiplexing parallel samples in microliter volumes

Immunoassays are widely utilized due to their ability to quantify a vast assortment of biomolecules relevant to biological research and clinical diagnostics. Recently, immunoassay capabilities have been improved by the development of multiplex assays that simultaneously measure multiple analytes in a single sample. However, these assays are hindered by high costs of reagents and relatively large sample requirements. For example, in vitro screening systems currently dedicate individual wells to each time point of interest and this limitation is amplified in screening studies when the investigation of many experimental conditions is necessary; resulting in large volumes for analysis, a correspondingly high cost and a limited temporal experimental design. Microfluidics based immunoassays have been developed in order to overcome these drawbacks. Together, previous studies have demonstrated on-chip assays with either a large dynamic range, high performance sensitivity, and/or the ability to process samples in parallel on a single chip. In this report, we develop a multiplex immunoassay possessing all of these parallel characteristics using commercially available reagents, which allows the analytes of interest to be easily changed. The device presented can measure 6 proteins in 32 samples simultaneously using only 4.2 μL of sample volume. High quality standard curves are generated for all 6 analytes included in the analysis, and spiked samples are quantified throughout the working range of the assay. In addition, we demonstrate a strong correlation (R(2) = 0.8999) between in vitro supernatant measurements using our device and those obtained from a bench-top multiplex immunoassay. Finally, we describe cytokine secretion in an in vitro inflammatory hippocampus culture system, establishing proof-of-concept of the ability to use this platform as an in vitro screening tool. The low-volume, multiplexing abilities of the microdevice described in this report could be broadly applied to numerous situations where sample volumes and costs are limiting.

Methylprednisolone for the Treatment of Patients with Acute Spinal Cord Injuries: A Propensity Score-Matched Cohort Study from a Canadian Multi-Center Spinal Cord Injury Registry

In prior analyses of the effectiveness of methylprednisolone for the treatment of patients with acute traumatic spinal cord injuries (TSCIs), the prognostic importance of patients' neurological levels of injury and their baseline severity of impairment has not been considered. Our objective was to determine whether methylprednisolone improved motor recovery among participants in the Rick Hansen Spinal Cord Injury Registry (RHSCIR). We identified RHSCIR participants who received methylprednisolone according to the Second National Spinal Cord Injury Study (NASCIS-II) protocol and used propensity score matching to account for age, sex, time of neurological exam, varying neurological level of injury, and baseline severity of neurological impairment. We compared changes in total, upper extremity, and lower extremity motor scores using the Wilcoxon signed-rank test and performed sensitivity analyses using negative binomial regression. Forty-six patients received methylprednisolone and 1555 received no steroid treatment. There were no significant differences between matched participants for each of total (13.7 vs. 14.1, respectively; p=0.43), upper extremity (7.3 vs. 6.4; p=0.38), and lower extremity (6.5 vs. 7.7; p=0.40) motor recovery. This result was confirmed using a multivariate model and, as predicted, only cervical (C1-T1) rather than thoracolumbar (T2-L3) injury levels (p<0.01) and reduced baseline injury severity (American Spinal Injury Association [ASIA] Impairment Scale grades; p<0.01) were associated with greater motor score recovery. There was no in-hospital mortality in either group; however, the NASCIS-II methylprednisolone group had a significantly higher rate of total complications (61% vs. 36%; p=0.02) NASCIS-II methylprednisolone did not improve motor score recovery in RHSCIR patients with acute TSCIs in either the cervical or thoracic spine when the influence of anatomical level and severity of injury were included in the analysis. There was a significantly higher rate of total complications in the NASCIS-II methylprednisolone group. These findings support guideline recommendations against routine administration of methylprednisolone in acute TSCI.

Diagnostic Value of Serum Levels of GFAP, pNF-H, and NSE Compared With Clinical Findings in Severity Assessment of Human Traumatic Spinal Cord Injury

STUDY DESIGN

An analytical cohort study.

OBJECTIVE

This study aimed to evaluate severity of traumatic spinal cord injury (SCI) based on the serum levels of phosphorylated form of heavy subunit of neurofilament (pNF-H), neuron-specific enolase (NSE), and glial fibrillary acidic protein (GFAP), which are axonal, neural cell body, and glial cell injury markers, respectively.

SUMMARY OF BACKGROUND DATA

Prior studies have reported elevated serum levels of pNF-H, NSE, and GFAP as biomarkers for the detection of traumatic SCI in animals. However, in this study, these biomarkers were studied in humans and with an extended level of timing.

METHODS

The study included 35 patients with SCI with a mean age of 36.5 years. All patients were evaluated using the American Spinal Injury Association Impairment Scale, followed by examinations including radiography and spinal computed tomography for determining the injury level. Serum levels of NSE, pNF-H, and GFAP were determined using enzyme-linked immunosorbent assay.

RESULTS

The mean serum level of GFAP was significantly higher in patients with SCI than in the control group. Mean serum levels of pNF-H and NSE were significantly higher during 24 and 48 hours after injury in patients with SCI than in the control group. The serum level of GFAP was appropriate for estimating the severity of SCI in the first 24 hours after injury.

CONCLUSION

Our findings suggest that increased serum levels of GFAP, NSE, and pNF-H can be used for the diagnosis and degree of SCI severity in trauma patients. During 48 hours after injury, estimation of serum levels of pNF-H, NSE, and GFAP, combined with neurological testing, could predict the presence of SCI and severity prior to spinal computed tomography and surgical or conservative interventions.

LEVEL OF EVIDENCE

2.

Serum neurofilament light chain is a biomarker of human spinal cord injury severity and outcome

BACKGROUND

Neurofilaments (Nf) are major structural proteins that occur exclusively in neurons. In spinal cord injury (SCI), the severity of disease is quantified by clinical measures that have limited sensitivity and reliability, and no blood-based biomarker has been established to further stratify the degree of injury. We aimed to examine a serum-based NfL immunoassay as predictor of the clinical outcome in SCI.

METHODS

Longitudinal measurement of serum NfL was performed in patients with central cord syndrome (CCS, n=4), motor-incomplete SCI (iSCI, n=10), motor-complete SCI (cSCI, n=13) and healthy controls (HC, n=67), and correlated with clinical severity, neurological outcome, and neuroprotective effect of the drug minocycline.

RESULTS

Baseline NfL levels were higher in iSCI (21 pg/mL) and cSCI (70 pg/mL) than in HC (5 pg/mL, p=0.006 and p<0.001) and CCS (6 pg/mL, p=0.025 and p=0.010). Levels increased over time (p<0.001) and remained higher in cSCI versus iSCI (p=0.011) and than in CCS (p<0.001). NfL levels correlated with American Spinal Injury Association (ASIA) motor score at baseline (r=-0.53, p=0.004) and after 24 h (r=-0.69, p<0.001) and 3-12-month motor outcome (baseline NfL: r=-0.43, p=0.026 and 24 h NfL: r=-0.72, p<0.001). Minocycline treatment showed decreased NfL levels in the subgroup of cSCI patients.

CONCLUSIONS

Serum NfL concentrations in SCI patients show a close correlation with acute severity and neurological outcome. Our data provide evidence that serum NfL is of prognostic value in SCI patients for the first time. Further, blood NfL levels may qualify as drug response markers in SCI.

Spinal cord injury: how can we improve the classification and quantification of its severity and prognosis?

The preservation of functional neural tissue after spinal cord injury (SCI) is the basis for spontaneous neurological recovery. Some injured patients in the acute phase have more potential for recovery than others. This fact is problematic for the construction of clinical trials because enrollment of subjects with variable recovery potential makes it difficult to detect effects, requires large sample sizes, and risks Type II errors. In addition, the current methods to assess injury and recovery are non-quantitative and not sensitive. It is likely that therapeutic combinations will be necessary to cause substantially improved function after SCI, thus we need highly sensitive techniques to evaluate changes in motor, sensory, autonomic and other functions. We review several emerging neurophysiological techniques with high sensitivity. Quantitative methods to evaluate residual tissue sparing after severe acute SCI have not entered widespread clinical use. This reduces the ability to correlate structural preservation with clinical outcome following SCI resulting in enrollment of subjects with varying patterns of tissue preservation and injury into clinical trials. We propose that the inclusion of additional measures of injury severity, pattern, and individual genetic characteristics may enable stratification in clinical trials to make the testing of therapeutic interventions more effective and efficient. New imaging techniques to assess tract injury and demyelination and methods to quantify tissue injury, inflammatory markers, and neuroglial biochemical changes may improve the evaluation of injury severity, and the correlation with neurological outcome, and measure the effects of treatment more robustly than is currently possible. The ability to test such a multimodality approach will require a high degree of collaboration between clinical and research centers and government research support. When the most informative of these assessments is determined, it may be possible to identify patients with substantial recovery potential, improve selection criteria and conduct more efficient clinical trials.

Non-mammalian model systems for studying neuro-immune interactions after spinal cord injury

Mammals exhibit poor recovery after injury to the spinal cord, where the loss of neurons and neuronal connections can be functionally devastating. In contrast, it has long been appreciated that many non-mammalian vertebrate species exhibit significant spontaneous functional recovery after spinal cord injury (SCI). Identifying the biological responses that support an organism's inability or ability to recover function after SCI is an important scientific and medical question. While recent advances have been made in understanding the responses to SCI in mammals, we remain without an effective clinical therapy for SCI. A comparative biological approach to understanding responses to SCI in non-mammalian vertebrates will yield important insights into mechanisms that promote recovery after SCI. Presently, mechanistic studies aimed at elucidating responses, both intrinsic and extrinsic to neurons, that result in different regenerative capacities after SCI across vertebrates are just in their early stages. There are several inhibitory mechanisms proposed to impede recovery from SCI in mammals, including reactive gliosis and scarring, myelin associated proteins, and a suboptimal immune response. One hypothesis to explain the robust regenerative capacity of several non-mammalian vertebrates is a lack of some or all of these inhibitory signals. This review presents the current knowledge of immune responses to SCI in several non-mammalian species that achieve anatomical and functional recovery after SCI. This subject is of growing interest, as studies increasingly show both beneficial and detrimental roles of the immune response following SCI in mammals. A long-term goal of biomedical research in all experimental models of SCI is to understand how to promote functional recovery after SCI in humans. Therefore, understanding immune responses to SCI in non-mammalian vertebrates that achieve functional recovery spontaneously may identify novel strategies to modulate immune responses in less regenerative species and promote recovery after SCI.

Cerebrospinal fluid inflammatory cytokines and chemokines in naturally occurring canine spinal cord injury

Canine intervertebral disk herniation (IVDH) is a common, naturally occurring form of spinal cord injury (SCI) that is increasingly being used in pre-clinical evaluation of therapies. Although IVDH bears critical similarities to human SCI with respect to lesion morphology, imaging features, and post-SCI treatment, limited data are available concerning secondary injury mechanisms. Here, we characterized cerebrospinal fluid (CSF) cytokines, and chemokines in dogs with acute, surgically treated, thoracolumbar IVDH (n=39) and healthy control dogs (n=21) to investigate early inflammatory events after SCI. A bioplex system was used to measure interleukin (IL)-2, -6, -7, -8, -10, -15, and -18, granulocyte macrophage colony-stimulating factor (GM-CSF), interferon gamma (IFN-γ), keratinocyte chemoattractant (KC)-like protein, IFN-γ-inducible protein-10, monocyte chemotactic protein 1 (MCP-1), and tumor necrosis factor alpha. Cytokine and chemokine concentrations in the CSF of healthy and SCI dogs were compared and, in SCI dogs, were correlated to the duration of SCI, behavioral measures of injury severity at the time of sampling, and neurological outcome 42 days post-SCI as determined by a validated ordinal score. IL-8 concentration was significantly higher in SCI cases than healthy controls (p=0.0013) and was negatively correlated with the duration of SCI (p=0.042). CSF MCP-1 and KC-like protein were positively correlated with CSF microprotein concentration in dogs with SCI (p<0.0001 and p=0.004). CSF MCP-1 concentration was negatively associated with 42-day postinjury outcome (p<0.0001). Taken together, these data indicate that cytokines and chemokines present after SCI in humans and rodent models are associated with SCI pathogenesis in canine IVDH.

Relationships between cerebrospinal fluid characteristics, injury severity, and functional outcome in dogs with and without intervertebral disk herniation

BACKGROUND

Cerebrospinal fluid (CSF) is commonly acquired in dogs with intervertebral disk herniation (IVDH) and is a common method to assess inflammatory responses following spinal cord injury (SCI).

OBJECTIVES

The purpose of the study was to describe relationships between cisternal CSF characteristics, behavioral measures of SCI, T2- weighted (T2W) hyperintensity on magnetic resonance imaging (MRI), and long-term outcome in dogs with IVDH. Diagnostic accuracy of CSF for differentiating IVDH from other myelopathies was also assessed.

METHODS

The retrospective case series included 727 dogs, 443 with thoracolumbar IVDH, 103 with cervical IVDH, and 181 with other spinal cord diseases. Signalment, initial neurologic function, ambulatory function at long-term follow-up, T2W MRI, and CSF variables were recorded for dogs with IVDH. Signalment, etiology, and CSF data were retrieved for dogs with other myelopathies. Associations between CSF predictors, diagnosis, and outcomes were assessed.

RESULTS

CSF total nucleated cell count (TNCC) increased with SCI severity (rho -0.256, P < .001) in dogs with IVDH, TNCC was significantly higher in the presence of T2W hyperintensity (P = .001) in dogs with thoracolumbar IVDH, but TNCC, RBC count, microprotein, and percent neutrophils decreased with increasing injury duration (rho -0.253, P < .001; rho -0.269, P < .001; rho -0.141, P = .004, and rho -0.356, P < .001, respectively). CSF characteristics were not accurate for differentiating IVDH from other spinal cord diseases.

CONCLUSIONS

In dogs with IVDH, CSF TNCC, RBC count, microprotein, and percent neutrophils are correlated with clinical aspects of SCI such as injury severity and duration, but cannot differentiate IVDH from other etiologies.

Dopamine: a parallel pathway for the modulation of spinal locomotor networks

The spinal cord contains networks of neurons that can produce locomotor patterns. To readily respond to environmental conditions, these networks must be flexible yet at the same time robust. Neuromodulators play a key role in contributing to network flexibility in a variety of invertebrate and vertebrate networks. For example, neuromodulators contribute to altering intrinsic properties and synaptic weights that, in extreme cases, can lead to neurons switching between networks. Here we focus on the role of dopamine in the control of stepping networks in the spinal cord. We first review the role of dopamine in modulating rhythmic activity in the stomatogastric ganglion (STG) and the leech, since work from these preparations provides a foundation to understand its role in vertebrate systems. We then move to a discussion of dopamine’s role in modulation of swimming in aquatic species such as the larval xenopus, lamprey and zebrafish. The control of terrestrial walking in vertebrates by dopamine is less studied and we review current evidence in mammals with a focus on rodent species. We discuss data suggesting that the source of dopamine within the spinal cord is mainly from the A11 area of the diencephalon, and then turn to a discussion of dopamine’s role in modulating walking patterns from both in vivo and in vitro preparations. Similar to the descending serotonergic system, the dopaminergic system may serve as a potential target to promote recovery of locomotor function following spinal cord injury (SCI); evidence suggests that dopaminergic agonists can promote recovery of function following SCI. We discuss pharmacogenetic and optogenetic approaches that could be deployed in SCI and their potential tractability. Throughout the review we draw parallels with both noradrenergic and serotonergic modulatory effects on spinal cord networks. In all likelihood, a complementary monoaminergic enhancement strategy should be deployed following SCI.

Biomaterial-based interventions for neuronal regeneration and functional recovery in rodent model of spinal cord injury: a systematic review

CONTEXT

There is considerable interest in translating laboratory advances in neuronal regeneration following spinal cord injury (SCI). A multimodality approach has been advocated for successful functional neuronal regeneration. With this goal in mind several biomaterials have been employed as neuronal bridges either to support cellular transplants, to release neurotrophic factors, or to do both. A systematic review of this literature is lacking. Such a review may provide insight to strategies with a high potential for further investigation and potential clinical application.

OBJECTIVE

To systematically review the design strategies and outcomes after biomaterial-based multimodal interventions for neuronal regeneration in rodent SCI model. To analyse functional outcomes after implantation of biomaterial-based multimodal interventions and to identify predictors of functional outcomes.

METHODS

A broad PubMed, CINHAL, and a manual search of relevant literature databases yielded data from 24 publications; 14 of these articles included functional outcome information. Studies reporting behavioral data in rat model of SCI and employing biodegradable polymer-based multimodal intervention were included. For behavioral recovery, studies using severe injury models (transection or severe clip compression (>16.9 g) or contusion (50 g/cm)) were categorized separately from those investigating partial injury models (hemisection or moderate-to-severe clip compression or contusion).

RESULTS

The cumulative mean improvements in Basso, Beattie, and Bresnahan scores after biomaterial-based interventions are 5.93 (95% CI = 2.41 - 9.45) and 4.44 (95% CI = 2.65 - 6.24) for transection and hemisection models, respectively. Factors associated with improved outcomes include the type of polymer used and a follow-up period greater than 6 weeks.

CONCLUSION

The functional improvement after implantation of biopolymer-based multimodal implants is modest. The relationship with neuronal regeneration and functional outcome, the effects of inflammation at the site of injury, the prolonged survival of supporting cells, the differentiation of stem cells, the effective delivery of neurotrophic factors, and longer follow-up periods are all topics for future elucidation. Future investigations should strive to further define specific factors associated with improved functional outcomes in clinically relevant models.

Pilot study: elevated circulating levels of the proinflammatory cytokine macrophage migration inhibitory factor in patients with chronic spinal cord injury

OBJECTIVE

To test the hypothesis that the proinflammatory cytokine macrophage migration inhibitory factor (MIF) is elevated in the circulation of patients with chronic spinal cord injury (SCI) relative to uninjured subjects, and secondarily to identify additional immune mediators that are elevated in subjects with chronic SCI.

DESIGN

Prospective, observational pilot study.

SETTING

Outpatient clinic of a department of physical medicine and rehabilitation and research institute in an academic medical center.

PARTICIPANTS

Individuals with chronic (>1y from initial injury) SCI (n=22) and age- and sex-matched uninjured subjects (n=19).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Plasma levels of MIF, as determined by a commercially available multiplex suspension immunoassay. The relationship between MIF levels and clinical/demographic variables was also examined. As a secondary outcome, we evaluated other cytokines, chemokines, and growth factors.

RESULTS

Plasma MIF levels were significantly higher in subjects with chronic SCI than in control subjects (P<.001). Elevated MIF levels were not correlated significantly with any one clinical or demographic characteristic. Subjects with SCI also exhibited significantly higher plasma levels of monokine induced by interferon-gamma/chemokine C-X-C motif ligand 9 (P<.03), macrophage colony stimulating factor (P<.035), interleukin-3 (P<.044), and stem cell growth factor beta (SCGF-β) (P<.016). Among subjects with SCI, the levels of SCGF-β increased with the time from initial injury.

CONCLUSIONS

These data confirm the hypothesis that MIF is elevated in subjects with chronic SCI and identify additional novel immune mediators that are also elevated in these subjects. This study suggests the importance of examining the potential functional roles of MIF and other immune factors in subjects with chronic SCI.

Acute diagnostic biomarkers for spinal cord injury: review of the literature and preliminary research report

OBJECTIVE

Many efforts have been made to create new diagnostic technologies for use in the diagnosis of central nervous system injury. However, there is still no consensus for the use of biomarkers in clinical acute spinal cord injury (SCI). The aims of this review are (1) to evaluate the current status of neurochemical biomarkers and (2) to discuss their potential acute diagnostic role in SCI by reviewing the literature.

METHODS

PubMed (http://www.ncbi.nlm.nih.gov/pubmed) was searched up to 2012 to identify publications concerning diagnostic biomarkers in SCI. To support more knowledge, we also checked secondary references in the primarily retrieved literature.

RESULTS

Neurofilaments, cleaved-Tau, microtubule-associated protein 2, myelin basic protein, neuron-specific enolase, S100β, and glial fibrillary acidic protein were identified as structural protein biomarkers in SCI by this review process. We could not find reports relating ubiquitin C-terminal hydrolase-L1 and α-II spectrin breakdown products, which are widely researched in other central nervous system injuries. Therefore, we present our preliminary data relating to these two biomarkers. Some of biomarkers showed promising results for SCI diagnosis and outcome prediction; however, there were unresolved issues relating to accuracy and their accessibility.

CONCLUSION

Currently, there still are not many reports focused on diagnostic biomarkers in SCI. This fact warranted the need for greater efforts to innovate sensitive and reliable biomarkers for SCI.

Multiplex array proteomics detects increased MMP-8 in CSF after spinal cord injury

Introduction

A variety of methods have been used to study inflammatory changes in the acutely injured spinal cord. Recently novel multiplex assays have been used in an attempt to overcome limitations in numbers of available targets studied in a single experiment. Other technical challenges in developing pre-clinical rodent models to investigate biomarkers in cerebrospinal fluid (CSF) include relatively small volumes of sample and low concentrations of target proteins. The primary objective of this study was to characterize the inflammatory profile present in CSF at a subacute time point in a clinically relevant rodent model of traumatic spinal cord injury (SCI). Our other aim was to test a microarray proteomics platform specifically for this application.

Methods

A 34 cytokine sandwich ELISA microarray was used to study inflammatory changes in CSF samples taken 12 days post-cervical SCI in adult rats. The difference between the median foreground signal and the median background signal was measured. Bonferroni and Benjamini-Hochburg multiple testing corrections were applied to limit the False Discovery Rate (FDR), and a linear mixed model was used to account for repeated measures in the array.

Results

We report a novel subacute SCI biomarker, elevated levels of matrix metalloproteinase-8 protein in CSF, and discuss application of statistical models designed for multiplex testing.

Conclusions

Major advantages of this assay over conventional methods include high-throughput format, good sensitivity, and reduced sample consumption. This method can be useful for creating comprehensive inflammatory profiles, and biomarkers can be used in the clinic to assess injury severity and to objectively grade response to therapy.

Acute spinal cord injury induces genetic damage in multiple organs of rats

Spinal cord injury (SCI) is a devastating condition with important functional and psychological consequences. However, the underlying mechanisms by which these alterations occur are still not fully understood. The aim of this study was to analyze genomic instability in multiple organs in the acute phase of SCI by means of single cell gel (comet) assay. Rats were randomly distributed into two groups (n = 5): a SHAM and a SCI group killed 24 h after cord transection surgery. The results pointed out genetic damage in blood cells as depicted by the tail moment results. DNA breakage was also detected in liver and kidney cells after SCI. Taken together, our results suggest that SCI induces genomic damage in multiple organs of Wistar rats.

Animal models of neurologic disorders: a nonhuman primate model of spinal cord injury

Primates are an important and unique animal resource. We have developed a nonhuman primate model of spinal cord injury (SCI) to expand our knowledge of normal primate motor function, to assess the impact of disease and injury on sensory and motor function, and to test candidate therapies before they are applied to human patients. The lesion model consists of a lateral spinal cord hemisection at the C7 spinal level with subsequent examination of behavioral, electrophysiological, and anatomical outcomes. Results to date have revealed significant neuroanatomical and functional differences between rodents and primates that impact the development of candidate therapies. Moreover, these findings suggest the importance of testing some therapeutic approaches in nonhuman primates prior to the use of invasive approaches in human clinical trials. Our primate model is intended to: 1) lend greater positive predictive value to human translatable therapies, 2) develop appropriate methods for human translation, 3) lead to basic discoveries that might not be identified in rodent models and are relevant to human translation, and 4) identify new avenues of basic research to "reverse-translate" important questions back to rodent models.

Vascular Pathology as a Potential Therapeutic Target in SCI

Acute traumatic spinal cord injury (SCI) is characterized by a progressive secondary degeneration which exacerbates the loss of penumbral tissue and neurological function. Here, we first provide an overview of the known pathophysiological mechanisms involving injured microvasculature and molecular regulators that contribute to the loss and dysfunction of existing and new blood vessels. We also highlight the differences between traumatic and ischemic injuries which may yield clues as to the more devastating nature of traumatic injuries, possibly involving toxicity associated with hemorrhage. We also discuss known species differences with implications for choosing models, their relevance and utility to translate new treatments towards the clinic. Throughout this review, we highlight the potential opportunities and proof-of-concept experimental studies for targeting therapies to endothelial cell-specific responses. Lastly, we comment on the need for vascular mechanisms to be included in drug development and non-invasive diagnostics such as serum and cerebrospinal fluid biomarkers and imaging of spinal cord pathology.

Stuck at the bench: Potential natural neuroprotective compounds for concussion

Background:

While numerous laboratory studies have searched for neuroprotective treatment approaches to traumatic brain injury, no therapies have successfully translated from the bench to the bedside. Concussion is a unique form of brain injury, in that the current mainstay of treatment focuses on both physical and cognitive rest. Treatments for concussion are lacking. The concept of neuro-prophylactic compounds or supplements is also an intriguing one, especially as we are learning more about the relationship of numerous sub-concussive blows and/or repetitive concussive impacts and the development of chronic neurodegenerative disease. The use of dietary supplements and herbal remedies has become more common place.

Methods:

A literature search was conducted with the objective of identifying and reviewing the pre-clinical and clinical studies investigating the neuroprotective properties of a few of the more widely known compounds and supplements.

Results:

There are an abundance of pre-clinical studies demonstrating the neuroprotective properties of a variety of these compounds and we review some of those here. While there are an increasing number of well-designed studies investigating the therapeutic potential of these nutraceutical preparations, the clinical evidence is still fairly thin.

Conclusion:

There are encouraging results from laboratory studies demonstrating the multi-mechanistic neuroprotective properties of many naturally occurring compounds. Similarly, there are some intriguing clinical observational studies that potentially suggest both acute and chronic neuroprotective effects. Thus, there is a need for future trials exploring the potential therapeutic benefits of these compounds in the treatment of traumatic brain injury, particularly concussion.