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

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

JOURNAL/nrgr/04.03/01300535-202406000-00035/inline-graphic1/v/2023-10-30T152229Z/r/image-tiff

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 factor α, 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.

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.

Prognostic value of the systemic inflammatory index (SII) and systemic inflammatory response index (SIRI) in patients with traumatic spinal cord injury

PURPOSE

The overwhelming inflammatory response plays a critical role in the secondary injury cascade of traumatic spinal cord injury (tSCI). The systemic immune inflammatory index (SII) and systemic inflammatory response index (SIRI) are two novel inflammatory biomarkers. The SII was calculated based on lymphocyte, neutrophil, and platelet counts, while the SIRI was calculated based on lymphocyte, neutrophil, and monocyte counts. Their prognostic value in patients with tSCI remains unclear.

METHODS

Patients with tSCI admitted within 24 h of trauma were retrospectively and consecutively enrolled. Peripheral blood samples were collected on admission. The primary outcome was American Spinal Injury Association Impairment Scale (AIS) grade conversion at discharge. Multivariable logistic regression analysis was performed to determine the relationship between SII and SIRI and AIS grade conversion. We performed receiver operating characteristic curve (ROC) analysis to assess the discriminative ability of SII, and SIRI in predicting AIS grade conversion.

RESULTS

Among 280 included patients, 77 (27.5%) had improved AIS grade conversion at discharge. After adjustment for confounders, SII was independently associated with AIS grade conversion (per SD, odds ratio [OR], 0.68; 95% confidence interval [CI] 0.47-0.98, p = 0.040), while the association between SIRI and AIS grade conversion was insignificant (per 1 SD, OR, 0.77; 95% CI 0.55-1.08, p = 0.130). The ROC analysis revealed that the SII had the best predictive value for AIS grade conversion (area under curve: 0.608, 95% CI 0.536-0.678).

CONCLUSIONS

Increased SII was independently associated with a decreased likelihood of improved AIS grade conversion.

Spinal Cord Injury: From MicroRNAs to Exosomal MicroRNAs

Spinal cord injury (SCI) is an unfortunate experience that may generate extensive sensory and motor disabilities due to the destruction and passing of nerve cells. MicroRNAs are small RNA molecules that do not code for proteins but instead serve to regulate protein synthesis by targeting messenger RNA's expression. After SCI, secondary damage like apoptosis, oxidative stress, inflammation, and autophagy occurs, and differentially expressed microRNAs show a function in these procedures. Almost all animal and plant cells release exosomes, which are sophisticated formations of lipid membranes. These exosomes have the capacity to deliver significant materials, such as proteins, RNAs and lipids, to cells in need, regulating their functions and serving as a way of communication. This new method offers a fresh approach to treating spinal cord injury. Obviously, the exosome has the benefit of conveying the transported material across performing regulatory activities and the blood-brain barrier. Among the exosome cargoes, microRNAs, which modulate their mRNA targets, show considerable promise in the pathogenic diagnosis, process, and therapy of SCI. Herein, we describe the roles of microRNAs in SCI. Furthermore, we emphasize the importance of exosomal microRNAs in this disease.

Studying missingness in spinal cord injury data: challenges and impact of data imputation

BACKGROUND

In the last decades, medical research fields studying rare conditions such as spinal cord injury (SCI) have made extensive efforts to collect large-scale data. However, most analysis methods rely on complete data. This is particularly troublesome when studying clinical data as they are prone to missingness. Often, researchers mitigate this problem by removing patients with missing data from the analyses. Less commonly, imputation methods to infer likely values are applied.

OBJECTIVE

Our objective was to study how handling missing data influences the results reported, taking the example of SCI registries. We aimed to raise awareness on the effects of missing data and provide guidelines to be applied for future research projects, in SCI research and beyond.

METHODS

Using the Sygen clinical trial data (n = 797), we analyzed the impact of the type of variable in which data is missing, the pattern according to which data is missing, and the imputation strategy (e.g. mean imputation, last observation carried forward, multiple imputation).

RESULTS

Our simulations show that mean imputation may lead to results strongly deviating from the underlying expected results. For repeated measures missing at late stages (> = 6 months after injury in this simulation study), carrying the last observation forward seems the preferable option for the imputation. This simulation study could show that a one-size-fit-all imputation strategy falls short in SCI data sets.

CONCLUSIONS

Data-tailored imputation strategies are required (e.g., characterisation of the missingness pattern, last observation carried forward for repeated measures evolving to a plateau over time). Therefore, systematically reporting the extent, kind and decisions made regarding missing data will be essential to improve the interpretation, transparency, and reproducibility of the research presented.

A New Paradigm in Spinal Cord Injury Therapy: from Cell-free Treatment to Engineering Modifications

Spinal cord injury (SCI) is an intractable and poorly prognostic neurological disease, and current treatments are still unable to cure it completely and avoid sequelae. Extracellular vesicles (EVs), as important carriers of intercellular communication and pharmacological effects, are considered to be the most promising candidates for SCI therapy because of their low toxicity and immunogenicity, their ability to encapsulate endogenous bioactive molecules (e.g., proteins, lipids, and nucleic acids), and their ability to cross the blood-brain/cerebrospinal barriers. However, poor targeting, low retention rate, and limited therapeutic efficacy of natural EVs have bottlenecked EVs-based SCI therapy. A new paradigm for SCI treatment will be provided by engineering modified EVs. Furthermore, our limited understanding of the role of EVs in SCI pathology hinders the rational design of novel EVbased therapeutic approaches. In this study, we review the pathophysiology after SCI, especially the multicellular EVs-mediated crosstalk; briefly describe the shift from cellular to cell-free therapies for SCI treatment; discuss and analyze the issues related to the route and dose of EVs administration; summarize and present the common strategies for EVs drug loading in the treatment of SCI and point out the shortcomings of these drug loading methods; finally, we analyze and highlight the feasibility and advantages of bio-scaffold-encapsulated EVs for SCI treatment, providing scalable insights into cell-free therapy for SCI.

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.

Subacute and Chronic Spinal Cord Injury: A Scoping Review of Epigenetics and Secondary Health Conditions

Background

Epigenetics studies the impact of environmental and behavioral factors on stable phenotypic changes; however, the state of the science examining epigenomic mechanisms of regulation related to secondary health conditions (SHCs) and neuroepigenetics in chronic spinal cord injury (SCI) remain markedly underdeveloped.

Objective

This scoping review seeks to understand the state of the science in epigenetics and secondary complications following SCI.

Methods

A literature search was conducted, yielding 277 articles. The inclusion criteria were articles (1) investigating SCI and (2) examining epigenetic regulation as part of the study methodology. A total of 23 articles were selected for final inclusion.

Results

Of the 23 articles 52% focused on histone modification, while 26% focused on DNA methylation. One study had a human sample, while the majority sampled rats and mice. Primarily, studies examined regeneration, with only one study looking at clinically relevant SHC, such as neuropathic pain.

Discussion

The findings of this scoping review offer exciting insights into epigenetic and neuroepigenetic application in SCI research. Several key genes, proteins, and pathways emerged across studies, suggesting the critical role of epigenetic regulation in biological processes. This review reinforced the dearth of studies that leverage epigenetic methods to identify prognostic biomarkers in SHCs. Preclinical models of SCI were genotypically and phenotypically similar, which is not reflective of the heterogeneity found in the clinical population of persons with SCI. There is a need to develop better preclinical models and more studies that examine the role of genomics and epigenomics in understanding the diverse health outcomes associated with traumatic SCI.

Spasticity Predicts Motor Recovery for Patients with Subacute Motor Complete Spinal Cord Injury

OBJECTIVE

A motor complete spinal cord injury (SCI) results in the loss of voluntary motor control below the point of injury. Some of these patients can regain partial motor function through inpatient rehabilitation; however, there is currently no biomarker to easily identify which patients have this potential. Evidence indicates that spasticity could be that marker. Patients with motor complete SCI who exhibit spasticity show preservation of descending motor pathways, the pathways necessary for motor signals to be carried from the brain to the target muscle. We hypothesized that the presence of spasticity predicts motor recovery after subacute motor complete SCI.

METHODS

Spasticity (Modified Ashworth Scale and pendulum test) and descending connectivity (motor evoked potentials) were tested in the rectus femoris muscle in patients with subacute motor complete (n = 36) and motor incomplete (n = 30) SCI. Motor recovery was assessed by using the International Standards for Neurological Classification of Spinal Cord Injury and the American Spinal Injury Association Impairment Scale (AIS). All measurements were taken at admission and discharge from inpatient rehabilitation.

RESULTS

We found that motor complete SCI patients with spasticity improved in motor scores and showed AIS conversion to either motor or sensory incomplete. Conversely, patients without spasticity showed no changes in motor scores and AIS conversion. In incomplete SCI patients, motor scores improved and AIS conversion occurred regardless of spasticity.

INTERPRETATION

These findings suggest that spasticity represents an easy-to-use clinical outcome that might help to predict motor recovery after severe SCI. This knowledge can improve inpatient rehabilitation effectiveness for motor complete SCI patients. ANN NEUROL 2023.

Current insights into the management of spinal cord injury

Background

Traumatic spinal cord injury (SCI) is a serious disorder that results in severe impairment of neurological function as well as disability, ultimately reducing a patient's quality of life. The pathophysiology of SCI involves a primary and secondary phase, which causes neurological injury.

Methods

Narrative review on current clinical management of spinal cord injury and emerging therapies.

Results

This review explores the management of SCI through early decompressive surgery, optimizing mean arterial pressure, steroid therapy and focused rehabilitation. These management strategies reduce secondary injury mechanisms to prevent the propagation of further neurological damage. The literature regarding emerging research is also explored in cell-based, gene, pharmacological and neuromodulation therapies, which aim to repair the spinal cord following the primary injury mechanism.

Conclusions

Outcomes for patients with SCI can be enhanced and improved if primary and secondary phases of SCI can be addressed.

Mesoporous polydopamine delivering 8-gingerol for the target and synergistic treatment to the spinal cord injury

In the treatment of spinal cord injury (SCI), the complex process of secondary injury is mainly responsible for preventing SCI repair or even exacerbating the injury. In this experiment, we constructed the 8-gingerol (8G)-loaded mesoporous polydopamine (M-PDA), M@8G, as the in vivo targeting nano-delivery platform, and investigated the therapeutic effects of M@8G in secondary SCI and its related mechanisms. The results indicated that M@8G could penetrate the blood-spinal cord barrier to enrich the spinal cord injury site. Mechanism research has shown that all of the M-PDA,8G and M@8G displayed the anti-lipid peroxidation effect, and then M@8G can inhibit the secondary SCI by suppressing the ferroptosis and inflammation. In vivo assays showed that M@8G significantly diminished the local injury area, reduced axonal and myelin loss, thus improving the neurological and motor recovery in rats. Based on the analysis of cerebrospinal fluid samples from patients, ferroptosis occurred locally in SCI and continued to progress in patients during the acute phase of SCI as well as the stage after their clinical surgery. This study showcases effective treatment of SCI through the aggregation and synergistic effect of M@8G in focal areas, providing a safe and promising strategy for the clinical treatment of SCI.

Association between Cerebrospinal Fluid and Serum Biomarker Levels and Diagnosis, Injury Severity, and Short-Term Outcomes in Patients with Acute Traumatic Spinal Cord Injury

Acute traumatic spinal cord injury (SCI) is recognized as a global problem that can lead to a range of acute and secondary complications impacting morbidity and mortality. There is still a lack of reliable diagnostic and prognostic biomarkers in patients with SCI that could help guide clinical care and identify novel therapeutic targets for future drug discovery. The aim of this prospective controlled study was to determine the cerebral spinal fluid (CSF) and serum profiles of 10 biomarkers as indicators of SCI diagnosis, severity, and prognosis to aid in assessing appropriate treatment modalities. CSF and serum samples of 15 SCI and ten healthy participants were included in the study. The neurological assessments were scored on admission and at discharge from the hospital using the American Spinal Injury Association Impairment Score (AIS) grades. The CSF and serum concentrations of SBDP150, S100B, GFAP, NF-L, UCHL-1, Tau, and IL-6 were significantly higher in SCI patients when compared with the control group. The CSF GBDP 38/44K, UCHL-L1, S100B, GFAP, and Tau levels were significantly higher in the AIS A patients. This study demonstrated a strong correlation between biomarker levels in the diagnosis and injury severity of SCI but no association with short-term outcomes. Future prospective controlled studies need to be done to support the results of this study.

Association of CSF and Serum Neurofilament Light and Glial Fibrillary Acidic Protein, Injury Severity, and Outcome in Spinal Cord Injury

BACKGROUND AND OBJECTIVES

Traumatic spinal cord injury (SCI) is highly heterogeneous, and tools to better delineate pathophysiology and recovery are needed. Our objective was to profile the response of 2 biomarkers, neurofilament light (NF-L) and glial fibrillary acidic protein (GFAP), in the serum and CSF of patients with acute SCI to evaluate their ability to objectively characterize injury severity and predict neurologic recovery.

METHODS

Blood and CSF samples were obtained from prospectively enrolled patients with acute SCI through days 1-4 postinjury, and the concentration of NF-L and GFAP was quantified using Simoa technology. Neurologic assessments defined the ASIA Impairment Scale (AIS) grade and motor score (MS) at presentation and 6 months postinjury.

RESULTS

One hundred eighteen patients with acute SCI (78 AIS A, 20 AIS B, and 20 AIS C) were enrolled, with 113 (96%) completing 6-month follow-up. NF-L and GFAP levels were strongly associated between paired serum and CSF specimens, were both increased with injury severity, and distinguished among baseline AIS grades. Serum NF-L and GFAP were significantly (p = 0.02 to <0.0001) higher in AIS A patients who did not improve at 6 months, predicting AIS grade conversion with a sensitivity and specificity (95% CI) of 76% (61, 87) and 77% (55, 92) using NF-L and 72% (57, 84) and 77% (55, 92) using GFAP at 72 hours, respectively. Independent of clinical baseline assessment, a serum NF-L threshold of 170 pg/mL at 72 hours predicted those patients who would be classified as motor complete (AIS A/B) compared with motor incomplete (AIS C/D) at 6 months with a sensitivity of 87% (76, 94) and specificity of 84% (69, 94); a serum GFAP threshold of 13,180 pg/mL at 72 hours yielded a sensitivity of 90% (80, 96) and specificity of 84% (69, 94).

DISCUSSION

The potential for NF-L and GFAP to classify injury severity and predict outcome after acute SCI will be useful for patient stratification and prognostication in clinical trials and inform communication of prognosis.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that higher serum NF-L and GFAP are associated with worse neurological outcome after acute SCI.

TRIAL REGISTRATION INFORMATION

Registered on ClinicalTrials.gov: NCT00135278 (March 2006) and NCT01279811 (January 2012).

Glial fibrillary acidic protein is a robust biomarker in cerebrospinal fluid and peripheral blood after traumatic spinal cord injury: a prospective pilot study

PURPOSE

Biochemical biomarkers to determine the injury severity and the potential for functional recovery of traumatic spinal cord injury (TSCI) are highly warranted; however, it remains to be clarified whether cerebrospinal fluid (CSF) or peripheral blood (PB) is the ideal sample media. This study aims to measure and compare biomarker concentrations in CSF and PB and to explore associations between biomarker concentrations and injury severity, i.e., American Spinal Injury Association (ASIA) Impairment Scale (AIS) grade, and biomarker concentrations and clinical outcome, i.e., AIS grade improvement and Spinal Cord Independent Measure version III (SCIM-III) score.

METHODS

From 2018 to 2020, we conducted a single-center prospective pilot study of TSCI patients (n=15) and healthy controls (n=15). Sample collection and clinical outcome assessment were performed at median 13 h [IQR: 19], 9 days [IQR: 2], and 148 days [IQR: 49] after TSCI. Concentrations of neuron-specific enolase (NSE); glial fibrillary acid protein (GFAP); neurofilament light chain (NfL); interferon-γ (IFN-γ); interleukin (IL)-1ß, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, and IL-13; and tumor necrosis factor α (TNF-α) were measured and associated to clinical outcomes.

RESULTS

The biomarker concentrations were higher in CSF than PB. CSF concentrations of GFAP, NSE, IFN-y, TNF-a, IL-2, IL-12p70, IL-4, IL-10, and IL-13 and PB concentrations of GFAP and IFN-y were significantly associated with AIS grade, but not with AIS grade improvement or SCIM-III score.

CONCLUSIONS

Our results support GFAP as a potential diagnostic biomarker that may be measured in CSF as well as PB.

Regenerative Effects of Exosomes-Derived MSCs: An Overview on Spinal Cord Injury Experimental Studies

Spinal cord injury (SCI) is a devastating condition usually induced by the initial mechanical insult that can lead to permanent motor and sensory deficits. At present, researchers are investigating potential therapeutic strategies to ameliorate the neuro-inflammatory cascade that occurs post-injury. Although the use of mesenchymal stromal/stem (MSCs) as a potential therapy in application to regenerative medicine promoted anti-inflammatory and neuroprotective effects, several disadvantages limit their use. Therefore, recent studies have reported the effects of exosomes-derived MSCs (MSC-EXOs) as an innovative therapeutic option for SCI patients. It is noteworthy that MSC-EXOs can maintain the integrity of the blood-spinal cord barrier (BSCB), promoting angiogenic, proliferative, and anti-oxidant effects, as well as immunomodulatory, anti-inflammatory, and antiapoptotic properties. Therefore, in this study, we summarized the preclinical studies reported in the literature that have shown the effects of MSC-EXOs as a new molecular target to counteract the devastating effects of SCI.

Specific Blood RNA Profiles in Individuals with Acute Spinal Cord Injury as Compared with Trauma Controls

Background

Spinal cord injury (SCI) is known to cause a more robust systemic inflammatory response than general trauma without CNS injury, inducing severe secondary organ damage, especially the lung and liver. Related studies are principally focused on the mechanisms underlying repair and regeneration in the injured spinal cord tissue. However, the specific mechanism of secondary injury after acute SCI is widely overlooked, compared with general trauma.

Methods

Two datasets of GSE151371 and GSE45376 related to the blood samples and spinal cord after acute SCI were selected to identify the differentially expressed genes (DEGs). In GSE151371, functional enrichment analysis on specific DEGs of blood samples was performed. And the top 15 specific hub genes were identified from intersectional genes between the specific upregulated DEGs of blood samples in GSE151371 and the upregulated DEGs of the spinal cord in GSE45376. The specific functional enrichment analysis and the drug candidates of the hub genes and the miRNAs-targeted hub genes were also analyzed and predicted.

Results

DEGs were identified, and a total of 64 specific genes were the intersection of upregulated genes of the spinal cord in GSE45376 and upregulated genes of human blood samples in GSE151371. The top 15 hub genes including HP, LCN2, DLGAP5, CEP55, HMMR, CDKN3, PRTN3, SKA3, MPO, LTF, CDC25C, MMP9, NEIL3, NUSAP1, and CD163 were calculated from the 64 specific genes. Functional enrichment analysis of the top 15 hub genes revealed inflammation-related pathways. The predicted miRNAs-targeted hub genes and drug candidates of hub genes were also performed to put forward reasonable treatment strategies.

Conclusion

The specific hub genes of acute SCI as compared with trauma without CNS injury were identified. The functional enrichment analysis of hub genes showed a specific immune response. Several predicted drugs of hub genes were also obtained. The hub genes and the predicted miRNAs may be potential biomarkers and therapeutic targets and require further validation.

The inflammatory response and blood-spinal cord barrier integrity in traumatic spinal cord injury: a prospective pilot study

PURPOSE

Triggering of inflammatory responses and disruption of blood-spinal cord barrier (BSCB) integrity are considered pivotal events in the pathophysiology of traumatic spinal cord injury (TSCI). Yet, these events are poorly understood and described in humans. This study aims to describe inflammatory responses and BSCB integrity in human TSCI.

METHODS

Fifteen TSCI patients and fifteen non-TSCI patients were prospectively recruited from Aarhus University Hospital, Denmark. Peripheral blood (PB) and cerebrospinal fluid (CSF) were collected at median day 0 [IQR: 1], median day 9 [IQR: 2], and median day 148 [IQR: 49] after injury. PB and CSF were analyzed for immune cells by flow cytometry, cytokines by multiplex immunoassay, and BSCB integrity by IgG Index.

RESULTS

Eleven TSCI patients completed follow-up. Results showed alterations in innate and adaptive immune cell counts over time. TSCI patients had significantly increased cytokine concentrations in CSF at the first and second follow-up, while only concentrations of interleukin (IL)-4, IL-8, and tumor necrosis factor-α remained significantly increased at the third follow-up. In PB, TSCI patients had significantly increased IL-6, IL-8, and IL-10 concentrations and significantly decreased interferon-γ concentrations at the first follow-up. Results further showed increased IgG Index indicative of BSCB disruption in seven TSCI patients at the first follow-up, five TSCI patients at the second follow-up, and two patients at the third follow-up.

CONCLUSIONS

Our results suggest that TSCI mainly triggers innate inflammatory responses that resolves over time, although with some degree of non-resolving inflammation, particularly in CSF. Our results cannot confirm BSCB disruption in all TSCI patients.

Molecular diagnostics in neurotrauma: Are there reliable biomarkers and effective methods for their detection?

To date, a large number of studies are being carried out in the field of neurotrauma, researchers not only establish the molecular mechanisms of the course of the disorders, but are also involved in the search for effective biomarkers for early prediction of the outcome and therapeutic intervention. Particular attention is paid to traumatic brain injury and spinal cord injury, due to the complex cascade of reactions in primary and secondary injury that affect pathophysiological processes and regenerative potential of the central nervous system. Despite a wide range of methods available methods to study biomarkers that correlate with the severity and degree of recovery in traumatic brain injury and spinal cord injury, development of reliable test systems for clinical use continues. In this review, we evaluate the results of recent studies looking for various molecules acting as biomarkers in the abovementioned neurotrauma. We also summarize the current knowledge of new methods for studying biological molecules, analyzing their sensitivity and limitations, as well as reproducibility of results. In this review, we also highlight the importance of developing reliable and reproducible protocols to identify diagnostic and prognostic biomolecules.

Advances in monitoring for acute spinal cord injury: a narrative review of current literature

Spinal cord injury (SCI) is a devastating condition that affects about 17,000 individuals every year in the United States, with approximately 294,000 people living with the ramifications of the initial injury. After the initial primary injury, SCI has a secondary phase during which the spinal cord sustains further injury due to ischemia, excitotoxicity, immune-mediated damage, mitochondrial dysfunction, apoptosis, and oxidative stress. The multifaceted injury progression process requires a sophisticated injury-monitoring technique for an accurate assessment of SCI patients. In this narrative review, we discuss SCI monitoring modalities, including pressure probes and catheters, micro dialysis, electrophysiologic measures, biomarkers, and imaging studies. The optimal next-generation injury monitoring setup should include multiple modalities and should integrate the data to produce a final simplified assessment of the injury and determine markers of intervention to improve patient outcomes.

Traumatic Nervous System Injury

Mechanisms of traumatic nervous system injury to a degree are similar, but differences exist in etiology, pathophysiology, and treatment of brain, spinal cord, and peripheral nerve injury. The most common clinical abnormalities seen in the horse are abnormal level of consciousness, abnormal behavior, seizures, cranial nerve deficits, vestibular disease, tetra- and paraparesis or paraplegia, cauda equina syndrome, specific gait deficits, and muscle atrophy. Treatments are directed toward reducing inflammation and swelling, halting secondary injury, and promoting mechanisms of neuroregeneration and plasticity. Prognosis depends on the severity of primary injury and the neuroanatomic location and extent of nervous tissue damage.

Enhancing Functional Recovery Through Intralesional Application of Extracellular Vesicles in a Rat Model of Traumatic Spinal Cord Injury

Local inflammation plays a pivotal role in the process of secondary damage after spinal cord injury. We recently reported that acute intravenous application of extracellular vesicles (EVs) secreted by human umbilical cord mesenchymal stromal cells dampens the induction of inflammatory processes following traumatic spinal cord injury. However, systemic application of EVs is associated with delayed delivery to the site of injury and the necessity for high doses to reach therapeutic levels locally. To resolve these two constraints, we injected EVs directly at the lesion site acutely after spinal cord injury. We report here that intralesional application of EVs resulted in a more robust improvement of motor recovery, assessed with the BBB score and sub-score, as compared to the intravenous delivery. Moreover, the intralesional application was more potent in reducing inflammation and scarring after spinal cord injury than intravenous administration. Hence, the development of EV-based therapy for spinal cord injury should aim at an early application of vesicles close to the lesion.

Cerebrospinal fluid and peripheral blood proteomics in Traumatic Spinal Cord Injury: A prospective pilot study

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Proteomics enable profiling of inflammatory responses after spinal cord injury.

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Proteins are differentially expressed over time.

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Proteins are differentially expressed in cerebrospinal fluid and peripheral blood.

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A poor relationship exists between protein expression and neurological outcome.

Altered diffusivity of the subarachnoid cisterns in the rat brain following neurological disorders

BACKGROUND

Although changes in diffusion characteristics of the brain parenchyma in neurological disorders are widely studied and used in clinical practice, the change in diffusivity in the cerebrospinal fluid (CSF) system is rarely reported. In this study, free water diffusion in the subarachnoid cisterns and ventricles of the rat brain was examined using diffusion magnetic resonance imaging (MRI), and the effects of neurological disorders on diffusivity in CSF system were investigated.

METHODS

Diffusion MRI and T₂-weighted images were obtained in the intact rats, 24 h after ischemic stroke, and 50 days after mild traumatic brain injury (mTBI). We conducted the assessment of diffusivity in the rat brain in the subarachnoid cisterns around the midbrain, as well as the lateral ventricles. One-way ANOVA and Kruskal-Wallis test were used to evaluate the change in mean diffusivity (MD) and MD histogram, respectively, in CSF system following different neurological disease.

RESULTS

A significant decrease in the mean MD value of the subarachnoid cisterns was observed in the stroke rats compared with the intact and mTBI rats (p < 0.005). In addition, the skewness (p < 0.002), maximum MD (p < 0.002), and MD percentiles (p < 0.002) in the stroke rats differed significantly from those in the intact and mTBI rats. By contrast, no difference was observed in the mean MD value of the lateral ventricles among three groups of rats. We proposed that the assessment of the subarachnoid cisterns, rather than the lateral ventricles, in the rat brain would be useful in providing diffusion information in the CSF system.

CONCLUSIONS

Alterations in MD parameters of the subarachnoid cisterns after stroke provide evidence that brain injury may alter the characteristics of free water diffusion not only in the brain parenchyma but also in the CSF system.

The Study of Cerebrospinal Fluid microRNAs in Spinal Cord Injury and Neurodegenerative Diseases: Methodological Problems and Possible Solutions

Despite extensive research on neurological disorders, unanswered questions remain regarding the molecular mechanisms underpinning the course of these diseases, and the search continues for effective biomarkers for early diagnosis, prognosis, or therapeutic intervention. These questions are especially acute in the study of spinal cord injury (SCI) and neurodegenerative diseases. It is believed that the changes in gene expression associated with processes triggered by neurological disorders are the result of post-transcriptional gene regulation. microRNAs (miRNAs) are key regulators of post-transcriptional gene expression and, as such, are often looked to in the search for effective biomarkers. We propose that cerebrospinal fluid (CSF) is potentially a source of biomarkers since it is in direct contact with the central nervous system and therefore may contain biomarkers indicating neurodegeneration or damage to the brain and spinal cord. However, since the abundance of miRNAs in CSF is low, their isolation and detection is technically difficult. In this review, we evaluate the findings of recent studies of CSF miRNAs as biomarkers of spinal cord injury (SCI) and neurodegenerative diseases. We also summarize the current knowledge concerning the methods of studying miRNA in CSF, including RNA isolation and normalization of the data, highlighting the caveats of these approaches and possible solutions.

Therapeutic Potential of Mesenchymal Stem Cells (MSCs) and MSC-Derived Extracellular Vesicles for the Treatment of Spinal Cord Injury

Spinal cord injury (SCI) is a life-threatening condition that leads to permanent disability with partial or complete loss of motor, sensory, and autonomic functions. SCI is usually caused by initial mechanical insult, followed by a cascade of several neuroinflammation and structural changes. For ameliorating the neuroinflammatory cascades, MSC has been regarded as a therapeutic agent. The animal SCI research has demonstrated that MSC can be a valuable therapeutic agent with several growth factors and cytokines that may induce anti-inflammatory and regenerative effects. However, the therapeutic efficacy of MSCs in animal SCI models is inconsistent, and the optimal method of MSCs remains debatable. Moreover, there are several limitations to developing these therapeutic agents for humans. Therefore, identifying novel agents for regenerative medicine is necessary. Extracellular vesicles are a novel source for regenerative medicine; they possess nucleic acids, functional proteins, and bioactive lipids and perform various functions, including damaged tissue repair, immune response regulation, and reduction of inflammation. MSC-derived exosomes have advantages over MSCs, including small dimensions, low immunogenicity, and no need for additional procedures for culture expansion or delivery. Certain studies have demonstrated that MSC-derived extracellular vesicles (EVs), including exosomes, exhibit outstanding chondroprotective and anti-inflammatory effects. Therefore, we reviewed the principles and patho-mechanisms and summarized the research outcomes of MSCs and MSC-derived EVs for SCI, reported to date.

Inflammation after spinal cord injury: a review of the critical timeline of signaling cues and cellular infiltration

Traumatic spinal cord injury (SCI) is a devastating neurological condition that results in a loss of motor and sensory function. Although extensive research to develop treatments for SCI has been performed, to date, none of these treatments have produced a meaningful amount of functional recovery after injury. The primary injury is caused by the initial trauma to the spinal cord and results in ischemia, oxidative damage, edema, and glutamate excitotoxicity. This process initiates a secondary injury cascade, which starts just a few hours post-injury and may continue for more than 6 months, leading to additional cell death and spinal cord damage. Inflammation after SCI is complex and driven by a diverse set of cells and signaling molecules. In this review, we utilize an extensive literature survey to develop the timeline of local immune cell and cytokine behavior after SCI in rodent models. We discuss the precise functional roles of several key cytokines and their effects on a variety of cell types involved in the secondary injury cascade. Furthermore, variations in the inflammatory response between rats and mice are highlighted. Since current SCI treatment options do not successfully initiate functional recovery or axonal regeneration, identifying the specific mechanisms attributed to secondary injury is critical. With a more thorough understanding of the complex SCI pathophysiology, effective therapeutic targets with realistic timelines for intervention may be established to successfully attenuate secondary damage.

The Unique Properties of Placental Mesenchymal Stromal Cells: A Novel Source of Therapy for Congenital and Acquired Spinal Cord Injury

Spinal cord injury (SCI) is a devasting condition with no reliable treatment. Spina bifida is the most common cause of congenital SCI. Cell-based therapies using mesenchymal stem/stromal cells (MSCS) have been largely utilized in SCI. Several clinical trials for acquired SCI use adult tissue-derived MSC sources, including bone-marrow, adipose, and umbilical cord tissues. The first stem/stromal cell clinical trial for spina bifida is currently underway (NCT04652908). The trial uses early gestational placental-derived mesenchymal stem/stromal cells (PMSCs) during the fetal repair of myelomeningocele. PMSCs have been shown to exhibit unique neuroprotective, angiogenic, and antioxidant properties, all which are promising applications for SCI. This review will summarize the unique properties and current applications of PMSCs and discuss their therapeutic role for acquired 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.

Application value of biofluid-based biomarkers for the diagnosis and treatment of spinal cord injury

Recent studies in patients with spinal cord injuries (SCIs) have confirmed the diagnostic potential of biofluid-based biomarkers, as a topic of increasing interest in relation to SCI diagnosis and treatment. This paper reviews the research progress and application prospects of recently identified SCI-related biomarkers. Many structural proteins, such as glial fibrillary acidic protein, S100-β, ubiquitin carboxy-terminal hydrolase-L1, neurofilament light, and tau protein were correlated with the diagnosis, American Spinal Injury Association Impairment Scale, and prognosis of SCI to different degrees. Inflammatory factors, including interleukin-6, interleukin-8, and tumor necrosis factor α, are also good biomarkers for the diagnosis of acute and chronic SCI, while non-coding RNAs (microRNAs and long non-coding RNAs) also show diagnostic potential for SCI. Trace elements (Mg, Se, Cu, Zn) have been shown to be related to motor recovery and can predict motor function after SCI, while humoral markers can reflect the pathophysiological changes after SCI. These factors have the advantages of low cost, convenient sampling, and ease of dynamic tracking, but are also associated with disadvantages, including diverse influencing factors and complex level changes. Although various proteins have been verified as potential biomarkers for SCI, more convincing evidence from large clinical and prospective studies is thus required to identify the most valuable diagnostic and prognostic biomarkers for SCI.

Serum Levels of Glial Fibrillary Acidic Protein and Neurofilament Light Protein Are Related to the Neurological Impairment and Spinal Edema after Traumatic Spinal Cord Injury

Neurological examination in the acute phase after spinal cord injury (SCI) is often impossible and severely confounded by pharmacological sedation or concomitant injuries. Therefore, diagnostic biomarkers that objectively characterize severity or the presence of SCI are urgently needed to facilitate clinical decision-making. This study aimed to determine if serum markers of neural origin are related to: 1) presence and severity of SCI, and 2) magnetic resonance imaging (MRI) parameters in the very acute post-injury phase. We performed a secondary analysis of serological parameters, as well as MRI findings in patients with acute SCI (n = 38). Blood samples were collected between Days 1-4 post-injury. Serum protein levels of glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE), and neurofilament light protein (NfL) were determined. A group of 41 age- and sex-matched healthy individuals served as control group. In the group of individuals with SCI, pre-operative sagittal and axial T2-weighted and sagittal T1-weighted MRI scans were available for 21 patients. Serum markers of neural origin are different among individuals who sustained traumatic SCI depending on injury severity, and the extent of the lesion according to MRI in the acute injury phase. Unbiased Recursive Partitioning regression with Conditional Inference Trees (URP-CTREE) produced preliminary cut-off values for NfL (75.217 pg/mL) and GFAP (73.121 pg/mL), allowing a differentiation between individuals with SCI and healthy controls within the first 4 days after SCI. Serum proteins NfL and GFAP qualify as diagnostic biomarkers for the presence and severity of SCI in the acute post-injury phase, where the reliability of clinical exams is limited.

A Nomogram for Predicting Acute Respiratory Failure After Cervical Traumatic Spinal Cord Injury Based on Admission Clinical Findings

OBJECTIVES

Acute respiratory failure (ARF) is a common medical complication in patients with cervical traumatic spinal cord injury (TSCI). To identify independent predictors for ARF onset in patients who underwent cervical TSCI without premorbid respiratory diseases and to apply appropriate medical supports based on accurate prediction, a nomogram relating admission clinical information was developed for predicting ARF during acute care period.

METHODS

We retrospectively reviewed clinical profiles of patients who suffered cervical TSCI and were emergently admitted to Qingdao Municipal Hospital from 2014 to 2020 as the training cohort. Univariate analysis was performed using admission clinical variables to estimate associated factors and a nomogram for predicting ARF occurrence was generated based on the independent predictors from multivariate logistic regression analysis. This nomogram was assessed by concordance index for discrimination and calibration curve with internal-validated bootstrap strategy. Receiver operating characteristic curve was conducted to compare the predictive accuracy between the nomogram and the traditional gold standard, which combines neuroimaging and neurological measurements by using area under the receiver operating characteristic curve (AUC). An additional 56-patient cohort from another medical center was retrospectively reviewed as the test cohort for external validation of the nomogram.

RESULTS

162 patients were eligible for this study and were included in the training cohort, among which 25 individuals developed ARF and were recorded to endure more complications. Despite the aggressive treatments and prolonged intensive care unit cares, 14 patients insulted with ARF died. Injury level, American Spinal Injury Association Impairment Scale (AIS) grade, admission hemoglobin (Hb), platelet to lymphocyte ratio, and neutrophil percentage to albumin ratio (NPAR) were independently associated with ARF onset. The concordance index of the nomogram incorporating these predictors was 0.933 in the training cohort and 0.955 in the test cohort, although both calibrations were good. The AUC of the nomogram was equal to concordance index, which presented better predictive accuracy compared with previous measurements using neuroimaging and AIS grade (AUC 0.933 versus 0.821, Delong's test p < 0.001). Similar significant results were also found in the test cohort (AUC 0.955 versus 0.765, Delong's test p = 0.034). In addition, this nomogram was translated to a Web-based calculator that could generate individual probability for ARF in a visualized form.

CONCLUSIONS

The nomogram incorporating the injury level, AIS grade, admission Hb, platelet to lymphocyte ratio, and NPAR is a promising model to predict ARF in patients with cervical TSCI who are absent from previous respiratory dysfunction. This nomogram can be offered to clinicians to stratify patients, strengthen evidence-based decision-making, and apply appropriate individualized treatment in the field of acute clinical care.

Early clinical predictors of functional recovery following traumatic spinal cord injury: a population-based study of 143 patients

BACKGROUND

Traumatic spinal cord injuries (TSCI) are associated with uncertainty regarding the prognosis of functional recovery. The aim of the present study was to evaluate the potential of early clinical variables to predict the degree of functional independence assessed by Spinal Cord Independence Measure III (SCIM-III) up to 1 year after injury.

METHODS

Prospectively collected data from 143 SCI patients treated in Western Denmark during 2012-2019 were retrospectively analysed. Data analysis involved univariate methods and multivariable linear regression modelling total SCIM-III scores against age, gender, body mass index (BMI), comorbidity, American Spinal Injury Association (ASIA) Impairment Scale (AIS) grades A-B and C-D, ASIA Motor Score (AMS), timing of surgical treatment and occurrence of medical complications. Statistical significance was set at p < .05.

RESULTS

Univariate analyses indicated that variables significantly associated with decreased functional independence included increased age (p = .023), increased BMI (p = .012), pre-existing comorbidity (p = .001), AIS grades A-B (p < .001), decreased AMS (p < .001) and occurrence of medical complications (p < .001). However, in the multivariable regression model were pre-existing comorbidity (p = .010), AIS grades A-B (p < .001), low AMS (p < .001) and late surgical treatment (p = .018) significant predictors of decreased functional independence 1 year after injury.

CONCLUSION

TSCI patients with greatest potential for functional recovery up to 1 year after injury seem to be patients that immediately after trauma present with few or no comorbidities, who sustain motor-incomplete injuries and undergo early decompressive surgery.

Natural Progression of Routine Laboratory Markers after Spinal Trauma: A Longitudinal, Multi-Cohort Study

Our objective was to track and quantify the natural course of serological markers over the 1st year following spinal cord injury. For that purpose, data on serological markers, demographics, and injury characteristics were extracted from medical records of a clinical trial (Sygen) and an ongoing observational cohort study (Murnau study). The primary outcomes were concentration/levels/amount of commonly collected serological markers at multiple time points. Two-way analysis of variance (ANOVA) and mixed-effects regression techniques were used to account for the longitudinal data and adjust for potential confounders. Trajectories of serological markers contained in both data sources were compared using the slope of progression. Our results show that, at baseline (≤ 2 weeks post-injury), most serological markers were at pathological levels, but returned to normal values over the course of 6-12 months post-injury. The baseline levels and longitudinal trajectories were dependent on injury severity. More complete injuries were associated with more pathological values (e.g., hematocrit, ANOVA test; χ2 = 68.93, df = 3, adjusted p value <0.001, and χ2 = 73.80, df = 3, adjusted p value <0.001, in the Sygen and Murnau studies, respectively). Comparing the two databases revealed some differences in the serological markers, which are likely attributable to differences in study design, sample size, and standard of care. We conclude that because of trauma-induced physiological perturbations, serological markers undergo marked changes over the course of recovery, from initial pathological levels that normalize within a year. The findings from this study are important, as they provide a benchmark for clinical decision making and prospective clinical trials. All results can be interactively explored on the Haemosurveillance web site (https://jutzelec.shinyapps.io/Haemosurveillance/) and GitHub repository (https://github.com/jutzca/Systemic-effects-of-Spinal-Cord-Injury).

Characterization of Cerebrospinal Fluid Ubiquitin C-Terminal Hydrolase L1 as a Biomarker of Human Acute Traumatic Spinal Cord Injury

A major obstacle for translational research in acute spinal cord injury (SCI) is the lack of biomarkers that can objectively stratify injury severity and predict outcome. Ubiquitin C-terminal hydrolase L1 (UCH-L1) is a neuron-specific enzyme that shows promise as a diagnostic biomarker in traumatic brain injury (TBI), but has not been studied in SCI. In this study, cerebrospinal fluid (CSF) and serum samples were collected over the first 72-96 h post-injury from 32 acute SCI patients who were followed prospectively to determine neurological outcomes at 6 months post-injury. UCH-L1 concentration was measured using the Quanterix Simoa platform (Quanterix, Billerica, MA) and correlated to injury severity, time, and neurological recovery. We found that CSF UCH-L1 was significantly elevated by 10- to 100-fold over laminectomy controls in an injury severity- and time-dependent manner. Twenty-four-hour post-injury CSF UCH-L1 concentrations distinguished between American Spinal Injury Association Impairment Scale (AIS) A and AIS B, and AIS A and AIS C patients in the acute setting, and predicted who would remain "motor complete" (AIS A/B) at 6 months with a sensitivity of 100% and a specificity of 86%. AIS A patients who did not improve their AIS grade at 6 months post-injury were characterized by sustained elevations in CSF UCH-L1 up to 96 h. Similarly, the failure to gain >8 points on the total motor score at 6 months post-injury was associated with higher 24-h CSF UCH-L1. Unfortunately, serum UCH-L1 levels were not informative about injury severity or outcome. In conclusion, CSF UCH-L1 in acute SCI shows promise as a biomarker to reflect injury severity and predict outcome.

Early Predictors of Neurological Outcomes After Traumatic Spinal Cord Injury: A Systematic Review and Proposal of a Conceptual Framework

BACKGROUND

Neurological outcomes after traumatic spinal cord injury are variable and depend on patient-, trauma-, and treatment-related factors as well as on spinal cord injury characteristics, imaging, and biomarkers.

OBJECTIVE

The aims of the study were to identify and classify the early predictors of neurological outcomes after traumatic spinal cord injury.

DATA SOURCES

The Medline, PubMed, Embase, and the Cochrane Central Database were searched using medical subject headings. The search was extended to the reference lists of identified studies.

STUDY ELIGIBILITY CRITERIA

The study eligibility criteria were assessment of neurological outcomes as primary or secondary outcome, predictors collected during the acute phase after traumatic spinal cord injury, and multivariate design.

PARTICIPANTS

The participants were adult patients with traumatic spinal cord injury followed at least 3 mos after injury.

STUDY APPRAISAL AND SYNTHESIS METHODS

The quality of studies was assessed by two independent reviewers using the Study Quality Assessment Tools for Observational Cohort and Cross-sectional Studies. The studies' narrative synthesis relied on a classification of the predictors according to quantity, quality, and consistency of the evidence. Results were summarized in a conceptual framework.

RESULTS

Forty-nine articles were included. The initial severity of traumatic spinal cord injury (American Spinal Injury Association Impairment Scale, motor score, and neurological level of injury) was the strongest predictor of neurological outcomes: patients with more severe injury at admission presented poor neurological outcomes. Intramedullary magnetic resonance imaging signal abnormalities were also associated with neurological outcomes, as the presence of intramedullary hemorrhage was a factor of poor prognosis. Other largely studied predictors, such as age and surgical timing, showed some inconsistency in results depending on cutoffs. Younger age and early surgery were generally associated with good outcomes. Although widely studied, other factors, such as vertebral and associated injuries, failed to show association with outcomes. Cerebrospinal fluid inflammatory biomarkers, as emerging factors, were significantly associated with outcomes.

CONCLUSIONS

This study provides a comprehensive review of predictors of neurological outcomes after traumatic spinal cord injury. It also highlights the heterogeneity of outcomes used by studies to assess neurological recovery. The proposed conceptual framework classifies predictors and illustrates their relationships with outcomes.

Improving Diagnostic Workup Following Traumatic Spinal Cord Injury: Advances in Biomarkers

PURPOSE OF REVIEW

Traumatic spinal cord injury (SCI) is a life-changing event with drastic implications for patients due to sensorimotor impairment and autonomous dysfunction. Current clinical evaluations focus on the assessment of injury level and severity using standardized neurological examinations. However, they fail to predict individual trajectories of recovery, which highlights the need for the development of advanced diagnostics. This narrative review identifies recent advances in the search of clinically relevant biomarkers in the field of SCI.

RECENT FINDINGS

Advanced neuroimaging and molecular biomarkers sensitive to the disease processes initiated by the SCI have been identified. These biomarkers range from advanced neuroimaging techniques, neurophysiological readouts, and molecular biomarkers identifying the concentrations of several proteins in blood and CSF samples. Some of these biomarkers improve current prediction models based on clinical readouts. Validation with larger patient cohorts is warranted. Several biomarkers have been identified-ranging from imaging to molecular markers-that could serve as advanced diagnostic and hence supplement current clinical assessments.

Dynamics of Selected Biomarkers in Cerebrospinal Fluid During Complex Endovascular Aortic Repair - A Pilot Study

INTRODUCTION

Ischemic spinal cord injury (SCI) is a serious complication of complex aortic repair. Prophylactic cerebrospinal fluid (CSF) drainage, used to decrease lumbar cerebrospinal fluid (CSF) pressure, enables monitoring of CSF biomarkers that may aid in detecting impending SCI. We hypothesized that biomarkers, previously evaluated in traumatic SCI and brain injury, would be altered in CSF over time following complex endovascular aortic repair (cEVAR).

OBJECTIVES

To examine if a chosen cohort of CSF biomarker correlates to SCI and warrants further research.

METHODS

A prospective observational study on patients undergoing cEVAR with extensive aortic coverage. Vital parameters and CSF samples were collected on ten occasions during 72 hours post-surgery. A panel of ten biomarkers were analyzed (Neurofilament Light Polypeptide (NFL), Tau, Glial Fibrillary Acidic Protein (GFAP), Soluble Amyloid Precursos Protein (APP) α and β, Amyloid β 38, 40 and 42 (Aβ38, 40 and 42), Chitinase-3-like protein 1 (CHI3LI or YKL-40), Heart-type fatty acid binding protein (H-FABP).).

RESULTS

Nine patients (mean age 69, 7 males) were included. Median total aortic coverage was 68% [33, 98]. One patient died during the 30-day post-operative period. After an initial stable phase for the first few postoperative hours, most biomarkers showed an upward trend compared with baseline in all patients with >50% increase in value for NFL in 5/9 patients, in 7/9 patients for Tau and in 5/9 patients for GFAP. One patient developed spinal cord and supratentorial brain ischemia, confirmed with MRI. In this case, NF-L, GFAP and tau were markedly elevated compared with non-SCI patients (maximum increase compared with baseline in the SCI patient versus mean value of the maximal increase for all other patients: NF-L 367% vs 79%%, GFAP 95608% versus 3433%, tau 1020% vs 192%).

CONCLUSION

This study suggests an increase in all ten studied CSF biomarkers after coverage of spinal arteries during endovascular aortic repair. However, the pilot study was not able to establish a specific correlation between spinal fluid biomarker elevation and clinical symptoms of SCI due to small sample size and event rate.

Proteomic Portraits Reveal Evolutionarily Conserved and Divergent Responses to Spinal Cord Injury

Despite the emergence of promising therapeutic approaches in preclinical studies, the failure of large-scale clinical trials leaves clinicians without effective treatments for acute spinal cord injury (SCI). These trials are hindered by their reliance on detailed neurological examinations to establish outcomes, which inflate the time and resources required for completion. Moreover, therapeutic development takes place in animal models whose relevance to human injury remains unclear. Here, we address these challenges through targeted proteomic analyses of cerebrospinal fluid and serum samples from 111 patients with acute SCI and, in parallel, a large animal (porcine) model of SCI. We develop protein biomarkers of injury severity and recovery, including a prognostic model of neurological improvement at 6 months with an area under the receiver operating characteristic curve of 0.91, and validate these in an independent cohort. Through cross-species proteomic analyses, we dissect evolutionarily conserved and divergent aspects of the SCI response and establish the cerebrospinal fluid abundance of glial fibrillary acidic protein as a biochemical outcome measure in both humans and pigs. Our work opens up new avenues to catalyze translation by facilitating the evaluation of novel SCI therapies, while also providing a resource from which to direct future preclinical efforts.

• Targeted proteomic analysis of CSF and serum samples from 111 acute SCI patients.

• Single- and multiprotein biomarkers of injury severity and recovery.

• Parallel proteomic analysis in a large animal model identifies conserved biomarkers.

• Evolutionary conservation and divergence of the proteomic response to SCI.

Serum C-reactive protein is an early, simple and inexpensive prognostic marker for the progression of intramedullary lesion on magnetic resonance imaging from acute to subacute stage in patients with spinal cord injury

STUDY DESIGN

Retrospective chart audit.

OBJECTIVES

This study aimed to identify conventional routine blood testing biomarkers associated with the progression of intramedullary injured area in patients with spinal cord injury (SCI).

SETTING

A spinal cord injury center in Hokkaido, Japan.

METHODS

We retrospectively reviewed 71 consecutive adults with acute SCI who were admitted within 24 h after injury and diagnosed as American Spinal Injury Association Impairment Scale Grade A or B at admission. Participants were divided into the progression (P group) and no progression group (NP group) based on the change of the hyperintense signal abnormality in the spinal cord on magnetic resonance imaging from the time of admission to 4 weeks after injury. Individual characteristics and blood testing data obtained in the first 4 weeks after injury were compared between groups.

RESULTS

The P and NP groups were comprised of 16 and 55 participants, respectively. In univariate analyses, white blood cell (WBC) count on day 3 was significantly higher in group P than group NP (P = 0.021), as was serum C-reactive protein (CRP) level on day 3 (P = 0.015) and day 7 (P = 0.047). Multivariable analysis identified serum CRP level on day 3 as a significant independent prognostic factor for the progression of secondary SCI (OR, 1.138; 95% confidence interval, 1.01-1.28; P = 0.034).

CONCLUSIONS

Serum CRP level on day 3 after injury was a good predictor for the progression of intramedullary signal intensity change on MRI from acute to subacute stage in patients with SCI.

Diagnostic blood RNA profiles for human acute spinal cord injury

Diagnosis of spinal cord injury (SCI) severity at the ultra-acute stage is of great importance for emergency clinical care of patients as well as for potential enrollment into clinical trials. The lack of a diagnostic biomarker for SCI has played a major role in the poor results of clinical trials. We analyzed global gene expression in peripheral white blood cells during the acute injury phase and identified 197 genes whose expression changed after SCI compared with healthy and trauma controls and in direct relation to SCI severity. Unsupervised coexpression network analysis identified several gene modules that predicted injury severity (AIS grades) with an overall accuracy of 72.7% and included signatures of immune cell subtypes. Specifically, for complete SCIs (AIS A), ROC analysis showed impressive specificity and sensitivity (AUC: 0.865). Similar precision was also shown for AIS D SCIs (AUC: 0.938). Our findings indicate that global transcriptomic changes in peripheral blood cells have diagnostic and potentially prognostic value for SCI severity.

Mesenchymal stem cell-derived exosomes: therapeutic opportunities and challenges for spinal cord injury

Spinal cord injury (SCI) often leads to serious motor and sensory dysfunction of the limbs below the injured segment. SCI not only results in physical and psychological harm to patients but can also cause a huge economic burden on their families and society. As there is no effective treatment method, the prevention, treatment, and rehabilitation of patients with SCI have become urgent problems to be solved. In recent years, mesenchymal stem cells (MSCs) have attracted more attention in the treatment of SCI. Although MSC therapy can reduce injured volume and promote axonal regeneration, its application is limited by tumorigenicity, a low survival rate, and immune rejection. Accumulating literature shows that exosomes have great potential in the treatment of SCI. In this review, we summarize the existing MSC-derived exosome studies on SCI and discuss the advantages and challenges of treating SCI based on exosomes derived from MSCs.

Early CSF Biomarkers and Late Functional Outcomes in Spinal Cord Injury. A Pilot Study

Although, biomarkers are regarded as an important tool for monitoring injury severity and treatment efficacy, and for predicting clinical evolution in many neurological diseases and disorders including spinal cord injury, there is still a lack of reliable biomarkers for the assessment of clinical course and patient outcome. In this study, a biological dataset of 60 cytokines/chemokines, growth factorsm and intracellular and extracellular matrix proteins, analyzed in CSF within 24 h of injury, was used for correlation analysis with the clinical dataset of the same patients. A heat map was generated of positive and negative correlations between biomarkers and clinical rating scale scores at discharge, and between biomarkers and changes in clinical scores during the observation period. Using very stringent statistical criteria, we found 10 molecules which correlated with clinical scores at discharge, and five molecules, which correlated with changes in clinical scores. The proposed methodology may be useful for generating hypotheses regarding "predictive" and "treatment effectiveness" biomarkers, thereby suggesting potential candidates for disease-modifying therapies using a "bed-to-bench" approach.

Predictive Value of Midsagittal Tissue Bridges on Functional Recovery After Spinal Cord Injury

Background

The majority of patients with spinal cord injury (SCI) have anatomically incomplete lesions and present with preserved tissue bridges, yet their outcomes vary.

Objective

To assess the predictive value of the anatomical location (ventral/dorsal) and width of preserved midsagittal tissue bridges for American Spinal Injury Association (ASIA) Impairment Scale (AIS) grade conversion and SCI patient stratification into recovery-specific subgroups.

Methods

This retrospective longitudinal study includes 70 patients (56 men, age: 52.36 ± 18.58 years) with subacute (ie, 1 month) SCI (45 tetraplegics, 25 paraplegics), 1-month neuroimaging data, and 1-month and 12-month clinical data. One-month midsagittal T2-weighted scans were used to determine the location and width of tissue bridges. Their associations with functional outcomes were assessed using partial correlation and unbiased recursive partitioning conditional inference tree (URP-CTREE).

Results

Fifty-seven (81.4%) of 70 patients had tissue bridges (2.53 ± 2.04 mm) at 1-month post-SCI. Larger ventral (P = .001, r = 0.511) and dorsal (P < .001, r = 0.546) tissue bridges were associated with higher AIS conversion rates 12 months post-SCI (n = 39). URP-CTREE analysis identified 1-month ventral tissue bridges as predictors of 12-month total motor scores (0.4 mm cutoff, P = .008), recovery of upper extremity motor scores at 12 months (1.82 mm cutoff, P = .002), 12-month pin-prick scores (1.4 mm cutoff, P = .018), and dorsal tissue bridges at 1 month as predictors of 12-month Spinal Cord Independence Measure scores (0.5 mm cutoff, P = .003).

Conclusions

Midsagittal tissue bridges add predictive value to baseline clinical measures for post-SCI recovery. Based on tissue bridges’ width, patients can be classified into subgroups of clinical recovery profiles. Midsagittal tissue bridges provide means to optimize patient stratification in clinical trials.

Cerebrospinal fluid levels of GFAP and pNF-H are elevated in patients with chronic spinal cord injury and neurological deterioration

BACKGROUND

Years after a traumatic spinal cord injury (SCI), a subset of patients may develop progressive clinical deterioration due to intradural scar formation and spinal cord tethering, with or without an associated syringomyelia. Meningitis, intradural hemorrhages, or intradural tumor surgery may also trigger glial scar formation and spinal cord tethering, leading to neurological worsening. Surgery is the treatment of choice in these chronic SCI patients.

OBJECTIVE

We hypothesized that cerebrospinal fluid (CSF) and plasma biomarkers could track ongoing neuronal loss and scar formation in patients with spinal cord tethering and are associated with clinical symptoms.

METHODS

We prospectively enrolled 12 patients with spinal cord tethering and measured glial fibrillary acidic protein (GFAP), ubiquitin C-terminal hydrolase L1 (UCH-L1), and phosphorylated Neurofilament-heavy (pNF-H) in CSF and blood. Seven patients with benign lumbar intradural tumors and 7 patients with cervical radiculopathy without spinal cord involvement served as controls.

RESULTS

All evaluated biomarker levels were markedly higher in CSF than in plasma, without any correlation between the two compartments. When compared with radiculopathy controls, CSF GFAP and pNF-H levels were higher in patients with spinal cord tethering (p ≤ 0.05). In contrast, CSF UCH-L1 levels were not altered in chronic SCI patients when compared with either control groups.

CONCLUSIONS

The present findings suggest that in patients with spinal cord tethering, CSF GFAP and pNF-H levels might reflect ongoing scar formation and neuronal injury potentially responsible for progressive neurological deterioration.

Ambulation in Dogs With Absent Pain Perception After Acute Thoracolumbar Spinal Cord Injury

Acute thoracolumbar spinal cord injury (SCI) is common in dogs frequently secondary to intervertebral disc herniation. Following severe injury, some dogs never regain sensory function to the pelvic limbs or tail and are designated chronically "deep pain negative." Despite this, a subset of these dogs develop spontaneous motor recovery over time including some that recover sufficient function in their pelvic limbs to walk independently without assistance or weight support. This type of ambulation is commonly known as "spinal walking" and can take up to a year or more to develop. This review provides a comparative overview of locomotion and explores the physiology of locomotor recovery after severe SCI in dogs. We discuss the mechanisms by which post-injury plasticity and coordination between circuitry contained within the spinal cord, peripheral sensory feedback, and residual or recovered supraspinal connections might combine to underpin spinal walking. The clinical characteristics of spinal walking are outlined including what is known about the role of patient or injury features such as lesion location, timeframe post-injury, body size, and spasticity. The relationship between the emergence of spinal walking and electrodiagnostic and magnetic resonance imaging findings are also discussed. Finally, we review possible ways to predict or facilitate recovery of walking in chronically deep pain negative dogs. Improved understanding of the mechanisms of gait generation and plasticity of the surviving tissue after injury might pave the way for further treatment options and enhanced outcomes in severely injured dogs.

Tau Pathology Triggered by Spinal Cord Injury Can Play a Critical Role in the Neurotrauma Development

Traumatic spinal cord injury (SCI) can result in substantial neurological impairment along with significant emotional and psychological distress. It is clear that there is profound neurodegeneration upon SCI, gradually spread to other spinal cord regions and brain areas. Despite extensive considerations, it remains uncertain how pathogenicity diffuses in the cord. It has been reported that tau protein abnormal hyperphosphorylation plays a central role in neurodegeneration triggered by traumatic brain injury (TBI). Tau is a microtubule-associated protein, heavily implicated in neurodegenerative diseases. Importantly, tau pathology spreads in a traumatic brain in a timely manner. In particular, we have recently demonstrated that phosphorylated tau at Thr231 exists in two distinct cis and trans conformations, in which that cis P-tau is extremely neurotoxic, has a prion nature, and spreads to various brain areas and cerebrospinal fluid (CSF) upon trauma. On the other hand, tau pathology, in particular hyperphosphorylation at Thr231, has been observed upon SCI. Taken these together, we conclude that cis pT231-tau may accumulate and spread in the spinal cord as well as CSF and diffuse tau pathology in the central nervous system (CNS). Moreover, antibody against cis P-tau can target intracellular cis P-tau and protect pathology spreading. Thus, considering cis P-tau as a driver of tau pathology and neurodegeneration upon SCI would open new windows toward understanding the disease development and early biomarkers. Furthermore, it would help us develop effective therapies for SCI patients.