Neuronal and axonal degeneration in experimental spinal cord injury: in vivo proton magnetic resonance spectroscopy and histology

Improved Recovery of Complete Spinal Cord Transection by a Plasma-Modified Fibrillar Scaffold

Complete spinal cord injury causes an irreversible disruption in the central nervous system, leading to motor, sensory, and autonomic function loss, and a secondary injury that constitutes a physical barrier preventing tissue repair. Tissue engineering scaffolds are presented as a permissive platform for cell migration and the reconnection of spared tissue. Iodine-doped plasma pyrrole polymer (pPPy-I), a neuroprotective material, was applied to polylactic acid (PLA) fibers and implanted in a rat complete spinal cord transection injury model to evaluate whether the resulting composite implants provided structural and functional recovery, using magnetic resonance (MR) imaging, diffusion tensor imaging and tractography, magnetic resonance spectroscopy, locomotion analysis, histology, and immunofluorescence. In vivo, MR studies evidenced a tissue response to the implant, demonstrating that the fibrillar composite scaffold moderated the structural effects of secondary damage by providing mechanical stability to the lesion core, tissue reconstruction, and significant motor recovery. Histologic analyses demonstrated that the composite scaffold provided a permissive environment for cell attachment and neural tissue guidance over the fibers, reducing cyst formation. These results supply evidence that pPPy-I enhanced the properties of PLA fibrillar scaffolds as a promising treatment for spinal cord injury recovery.

Glutathione in the Pons Is Associated With Clinical Status Improvements in Subacute Spinal Cord Injury

OBJECTIVES

In spinal cord injury (SCI), the primary mechanical injury is followed by secondary sequelae that develop over the subsequent months and manifests in biochemical, functional, and microstructural alterations, at the site of direct injury but also in the spinal cord tissue above and below the actual lesion site. Noninvasive magnetic resonance spectroscopy (MRS) can be used to assess biochemical modulation occurring in the secondary injury phase, in addition to and supporting conventional MRI, and might help predict and improve patient outcome. In this article, we aimed to examine the metabolic levels in the pons of subacute SCI by means of in vivo proton MRS at 3 T and explore the association to clinical scores.

MATERIALS AND METHODS

In this prospective study, between November 2015 and February 2018, single-voxel short-echo MRS data were acquired in healthy controls and in SCI subjects in the pons once during rehabilitation. Besides the single-point MRS examination, in addition, in participants with SCI, the clinical status (ie, motor, light touch, and pinprick scores) was assessed twice: (1) around the MRS session (approximately 10 weeks postinjury) and (2) before discharge (at approximately 9 months postinjury). The group differences were assessed with Kruskal-Wallis test, the post hoc comparison was assessed with Wilcoxon rank sum test, and the clinical correlations were conducted with Spearman rank correlation test. Bayes factor calculations completed the statistical part providing relevant evidence values.

RESULTS

Twenty healthy controls (median age, 50 years; interquartile range, 41-55 years; 18 men) and 18 subjects with traumatic SCI (median age, 50 years; interquartile range, 32-58 years; 16 men) are included. Group comparison showed an increase of total N -acetylaspartate and combined glutamate and glutamine levels in complete SCI and a reduction of total creatine in incomplete paraplegic SCI. The proton MRS-based glutathione levels at baseline correlate to the motor score improvement during rehabilitation in incomplete subacute SCI.

CONCLUSIONS

This exploratory study showed an association of the metabolite concentration of glutathione in the pons assessed at approximately 10 weeks after injury with the improvements of the motor score during the rehabilitation. Pontine glutathione levels in subjects with traumatic subacute incomplete SCI acquired remote from the injury site correlate to clinical score and might therefore be beneficial in the rehabilitation assessments.

Premarin Reduces Neurodegeneration and Promotes Improvement of Function in an Animal Model of Spinal Cord Injury

Spinal cord injury (SCI) causes significant mortality and morbidity. Currently, no FDA-approved pharmacotherapy is available for treating SCI. Previously, low doses of estrogen (17β-estradiol, E2) were shown to improve the post-injury outcome in a rat SCI model. However, the range of associated side effects makes advocating its therapeutic use difficult. Therefore, this study aimed at investigating the therapeutic efficacy of Premarin (PRM) in SCI. PRM is an FDA-approved E2 (10%) formulation, which is used for hormone replacement therapy with minimal risk of serious side effects. The effects of PRM on SCI were examined by magnetic resonance imaging, immunofluorescent staining, and western blot analysis in a rat model. SCI animals treated with vehicle alone, PRM, E2 receptor antagonist (ICI), or PRM + ICI were graded in a blinded way for locomotor function by using the Basso–Beattie–Bresnahan (BBB) locomotor scale. PRM treatment for 7 days decreased post-SCI lesion volume and attenuated neuronal cell death, inflammation, and axonal damage. PRM also altered the balance of pro- and anti-apoptotic proteins in favor of cell survival and improved angiogenesis and microvascular growth. Increased expression of estrogen receptors (ERs) ERα and ERβ following PRM treatment and their inhibition by ER inhibitor indicated that the neuroprotection associated with PRM treatment might be E2-receptor mediated. The attenuation of glial activation with decreased inflammation and cell death, and increased angiogenesis by PRM led to improved functional outcome as determined by the BBB locomotor scale. These results suggest that PRM treatment has significant therapeutic implications for the improvement of post-SCI outcome.

Correlation between functional MRI techniques and early disability in ambulatory patients with relapsing–remitting MS

Background

Multiple sclerosis (MS) is a common neurological disorder which can lead to an occasional damage to the central nervous system. Conventional magnetic resonance imaging (cMRI) is an important modality in the diagnosis of MS; however, correlation between cMRI findings and clinical impairment is weak. Non-conventional MRI techniques including apparent diffusion coefficient (ADC) and magnetic resonance spectroscopy (MRS) investigate the metabolic changes over the course of MS and overcome the limits of cMRI.

A total of 80 patients with MS and 20 age and sex-matched healthy control subjects were enrolled in this cross-sectional study. Ambulatory patients with relapsing–remitting MS (RRMS) were recruited. Expanded Disability Status Scale (EDSS) was used to assess the disability and the patients were categorized into three groups “no disability”, “minimal disability” and “moderate disability”. All patients underwent cMRI techniques. ADC was measured in MS plaques and in normal appearing white matter (NAWM) adjacent and around the plaque. All metabolites concentrations were expressed as ratios including N-acetyl-aspartate/creatine (NAA/Cr), choline/N-acetyl-aspartate (Cho/NAA) and choline/creatine (Cho/Cr). ADC and metabolite concentrations were measured in the normal white matter of 20 healthy control subjects.

Results

The study was carried on 80 MS patients [36 males (45%) and 44 females (55%)] and 20 healthy control [8 males (40%) and 12 females (60%)]. The ADC values and MRS parameters in NAWM of patients with MS were significantly different from those of the control group. The number of the plaques on T2 images and black holes were significantly higher at “Minimal disability” group. Most of the enhanced plaques were at the “Moderate disability” group with P value < 0.001. The mean of ADC in the group 1, 2 and 3 of disability was 1.12 ± 0.19, 1.50 ± 0.35, 1.51 ± 0.36, respectively, with P value < 0. 001. In the group 1, 2 and 3 of disability, the mean of NAA/Cr ratio at the plaque was 1.34 ± 0.44, 1.59 ± 0.51 and 1.11 ± 0.15, respectively, with P value equal 0.001.

Conclusion

The non-conventional quantitative MRI techniques are useful tools for detection of early disability in MS patients.

In vivo Molecular Signatures of Cervical Spinal Cord Pathology in Degenerative Compression

Degenerative cervical myelopathy (DCM) is a severe consequence of degenerative cervical spinal cord (CSC) compression. The non-myelopathic stage of compression (NMDC) is highly prevalent and often progresses to disabling DCM. This study aims to disclose markers of progressive neurochemical alterations in NMDC and DCM by utilizing an approach based on state-of-the-art proton magnetic resonance spectroscopy (¹H-MRS). Proton-MRS data were prospectively acquired from 73 participants with CSC compression and 47 healthy controls (HCs). The MRS voxel was centered at the C2 level. Compression-affected participants were clinically categorized as NMDC and DCM, radiologically as mild (MC) or severe (SC) compression. CSC volumes and neurochemical concentrations were compared between cohorts (HC vs. NMDC vs. DCM and HC vs. MC vs. SC) with general linear models adjusted for age and height (p_FWE < 0.05) and correlated to stenosis severity, electrophysiology, and myelopathy symptoms (p < 0.05). Whereas the ratio of total creatine (tCr) to total N-acetylaspartate (tNAA) increased in NMDC (+11%) and in DCM (+26%) and SC (+21%), myo-inositol/tNAA, glutamate + glutamine/tNAA, and volumes changed only in DCM (+20%, +73%, and −14%) and SC (+12%, +46%, and −8%, respectively) relative to HCs. Both tCr/tNAA and myo-inositol/tNAA correlated with compression severity and volume (−0.376 < r < −0.259). Myo-inositol/tNAA correlated with myelopathy symptoms (r = −0.670), whereas CSC volume did not. Short-echo ¹H-MRS provided neurochemical signatures of CSC impairment that reflected compression severity and clinical significance. Whereas volumetry only reflected clinically manifest myelopathy (DCM), MRS detected neurochemical changes already before the onset of myelopathy symptoms.

Low-Level Laser Therapy with 670 nm Alleviates Diabetic Retinopathy in an Experimental Model

Purpose:

To evaluate the effects of low-level laser therapy (LLLT) on the retina with diabetic retinopathy (DR).

Methods:

Eight Wistar rats were used as a control group, and 64 rats were injected intraperitoneally with 55 mg/kg of streptozotocin to induce diabetes and served as a diabetic group. After the establishment of the DR, the rats were separated into (a) 32 rats with DR; did not receive any treatment, (b) 32 rats with DR were exposed to 670 nm LLLT for 6 successive weeks (2 sessions/week). The retinal protein was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, total antioxidant capacity (TAC), hydrogen peroxide (H₂O₂), and histological examination.

Results:

LLLT improved retinal proteins such as neurofilament (NF) proteins (200 KDa, 160 KDa, and 86 KDa), neuron-specific enolase (NSE) (46 KDa). Moreover, the percentage changes in TAC were 46.8% (P < 0.001), 14.5% (P < 0.01), 4.8% and 1.6% (P > 0.05), and in H₂O_2, they were 30% (P < 0.001), 25% (P < 0.001), 20% (P < 0.01), and 5% (P > 0.05) after 1, 2, 4, and 6 weeks, compared with the control. DR displayed swelling and disorganization in the retinal ganglion cells (RGCs) and photoreceptors, congestion of the capillaries in the nerve fiber layer, thickening of the endothelial cells’ capillaries, and edema of the outer segment of the photoreceptors layer. The improvement of the retinal structure was achieved after LLLT.

Conclusion:

LLLT could modulate retinal proteins such as NSE and NFs, improve the RGCs, photoreceptors, and reduce the oxidative stress that originated in the retina from diabetes-induced DR.

Management of Traumatic Trigeminal and Facial Nerve Injuries

In the area of craniomaxillofacial trauma, neurosensory disturbances are encountered commonly, especially with regard to the trigeminal and facial nerve systems. This article reviews the specific microanatomy of both cranial nerves V and VII, and evaluates contemporary neurosensory testing, current imaging modalities, and available nerve injury classification systems. In addition, the article proposes treatment paradigms for management of trigeminal and facial nerve injuries, specifically with regard to the craniomaxillofacial trauma setting.

Focal white matter lesions induce long-lasting axonal degeneration, neuroinflammation and behavioral deficits

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) with episodes of inflammatory demyelination and remyelination. While remyelination has been linked with functional recovery in MS patients, there is evidence of ongoing tissue damage despite complete myelin repair. In this study, we investigated the long-term consequences of an acute demyelinating white matter CNS lesion. For this purpose, acute demyelination was induced by 5-week-cuprizone intoxication in male C57BL/6 J mice, and the tissues were examined after a 7-month recovery period. While myelination and oligodendrocyte densities appeared normal, ongoing axonal degeneration and glia cell activation were found in the remyelinated corpus callosum. Neuropathologies were paralleled by subtle gait abnormalities evaluated using DigiGait™ high speed ventral plane videography. Gene array analyses revealed increased expression levels of various inflammation related genes, among protein kinase c delta (PRKCD). Immunofluorescence stains revealed predominant microglia/macrophages PRKCD expression in both, cuprizone tissues and post-mortem MS lesions. These results support the hypothesis that chronic microglia/macrophages driven tissue injury represents a key aspect of progressive neurodegeneration and functional decline in MS.

Regenerative replacement of neural cells for treatment of spinal cord injury

Introduction: Traumatic Spinal Cord Injury (SCI) results from primary physical injury to the spinal cord, which initiates a secondary cascade of neural cell death. Current therapeutic approaches can attenuate the consequences of the primary and secondary events, but do not address the degenerative aspects of SCI. Transplantation of neural stem/progenitor cells (NPCs) for the replacement of the lost/damaged neural cells is suggested here as a regenerative approach that is complementary to current therapeutics.Areas Covered: This review addresses how neurons, oligodendrocytes, and astrocytes are impacted by traumatic SCI, and how current research in regenerative-NPC therapeutics aims to restore their functionality. Methods used to enhance graft survival, as well as bias progenitor cells towards neuronal, oligodendrogenic, and astroglia lineages are discussed.Expert Opinion: Despite an NPC's ability to differentiate into neurons, oligodendrocytes, and astrocytes in the transplant environment, their potential therapeutic efficacy requires further optimization prior to translation into the clinic. Considering the temporospatial identity of NPCs could promote neural repair in region specific injuries throughout the spinal cord. Moreover, understanding which cells are targeted by NPC-derived myelinating cells can help restore physiologically-relevant myelin patterns. Finally, the duality of astrocytes is discussed, outlining their context-dependent importance in the treatment of SCI.

The spatiotemporal spread of cervical spinal cord contusion injury pathology revealed by 3D in-line phase contrast synchrotron X-ray microtomography

Extensive structural changes occur within the spinal cord following traumatic injury. Acute tissue debris and necrotic tissue are broken down, proliferating local glia and infiltrating leukocytes remodel tissue biochemical and biophysical properties, and a chronic cavity surrounded by a scar forms at the injury epicentre. Serial-section 2D histology has traditionally assessed these features in experimental models of spinal cord injury (SCI) to measure the extent of tissue pathology and evaluate efficacy of novel therapies. However, this 2D snapshot approach overlooks slice intervening features, with accurate representation of tissue compromised by mechanical processing artefacts. 3D imaging avoids these caveats and allows full exploration of the injured tissue volume to characterise whole tissue pathology. Amongst 3D imaging modalities, Synchrotron Radiation X-ray microtomography (SRμCT) is advantageous for its speed, ability to cover large tissue volumes at high resolution, and need for minimal sample processing. Here we demonstrate how extended lengths of formalin-fixed, paraffin-embedded (FFPE) rat spinal cord can be completely imaged by SRμCT with micron resolution. Label-free contrast derived from X-ray phase interactions with low-density soft tissues, reveals spinal cord white matter, gray matter, tissue damage and vasculature, with tissue still viable for targeted 2D-histology after 3D imaging. We used SRμCT to quantify tissue pathology after a midline, cervical level (C6), 225 kDyne contusion injury over acute-to-chronic (24 h to 5 weeks) post injury time points. Quantification revealed acute tissue swelling prior to chronic atrophy across the whole imaged region (spanning 2 spinal segments above and below injury), along with rostro-caudal asymmetries in white and gray matter volume loss. 3D volumes revealed satellite damage in tissue far removed from the epicentre, and extensive rostro-caudal spread of damage through the base of the dorsal columns at 24 h post injury. This damage overlapped regions of vasogenic oedema, confirmed with subsequent histology. Tissue damage at later time points in border regions was most prominent in the dorsal columns, where it overlapped sites of damaged venous vasculature. Elaborating rostro-caudal and spatiotemporal asymmetries in reduced traumatic injury models centred on these regions may inform future treatments that seek to limit the spread of tissue pathology to these ‘at-risk’ regions.

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Whole rat spinal cord SRμCT tomograms (up to 20 mm length) with μm resolution

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Pathology of 3 SHAM and 24 acute-to-chronic C6 midline contusion SCIs quantified

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Rostro-caudal asymmetries in gray and white matter pathology progression

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Differences in ascending and descending dorsal column tract pathology

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Delayed rostral-caudal pathology associated with sites of venous vasculature

Shock waves promote spinal cord repair via TLR3

Spinal cord injury (SCI) remains a devastating condition with poor prognosis and very limited treatment options. Affected patients are severely restricted in their daily activities. Shock wave therapy (SWT) has shown potent regenerative properties in bone fractures, wounds, and ischemic myocardium via activation of the innate immune receptor TLR3. Here, we report on the efficacy of SWT for regeneration of SCI. SWT improved motor function and decreased lesion size in WT but not Tlr3-/- mice via inhibition of neuronal degeneration and IL6-dependent recruitment and differentiation of neuronal progenitor cells. Both SWT and TLR3 stimulation enhanced neuronal sprouting and improved neuronal survival, even in human spinal cord cultures. We identified tlr3 as crucial enhancer of spinal cord regeneration in zebrafish. Our findings indicate that TLR3 signaling is involved in neuroprotection and spinal cord repair and suggest that TLR3 stimulation via SWT could become a potent regenerative treatment option.

Gastrointestinal vascular permeability changes following spinal cord injury

BACKGROUND

Gastrointestinal (GI) dysfunction is observed clinically after spinal cord injury (SCI) and contributes to the diminished long-term quality of life. Our study examined the acute and chronic GI vascular changes that occur following SCI. We demonstrated that the GI vascular tract in SCI mice becomes compromised during the acute phase of injury and persists into the chronic phase of injury.

METHODS

Gastrointestinal vasculature permeability was measured using dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) at 48 hours, and 2 and 4 weeks following contusion spinal cord injury. Angiopoietin-1, a vascular stabilizing protein, was administered intravenously following injury. Intestinal contractile activity assessments were performed following the last imaging session.

KEY RESULTS

Our results indicated that a single administration of Ang-1 reduced vascular permeability at 48 hours but the effect was only transient. However, when the treatment paradigm was changed from a single administration to multiple administrations of Ang-1 following contusion injury, our DCE MRI data indicated a significant decrease in GI vascular permeability 4 weeks after injury compared with vehicle control treated animals. This improved GI vascular permeability was associated with improved sustained intestinal contractile activity. We also demonstrated that Ang-1 reduced the expression of sICAM-1 in the ileum compared with the saline-treated group.

CONCLUSIONS AND INFERENCES

We show that the GI vasculature is compromised in the acute and chronic phase of injury following spinal contusion. Our results also indicate that multiple administrations of Ang-1 can attenuate GI vascular permeability, possibly reduce inflammation, and improve sustained agonist-induced contraction compared with saline treatment.

Assessment of neuron-specific enolase, S100B and malondialdehyde levels in serum and vitreous of patients with proliferative diabetic retinopathy

PURPOSE

To assess the vitreous and serum levels of neuron-specific enolase (NSE), S100B and malondialdehyde (MDA) in proliferative diabetic retinopathy (PDR) cases and investigate the correlation between preoperative and postoperative anatomical and clinical features.

MATERIALS AND METHODS

The study group included patients who had pars plana vitrectomy (PPV) for PDR. The control group included non-diabetic individuals who underwent PPV surgery for vitreoretinal interface disorders. Samples of serum were taken from all participants preoperatively, while vitreous samples were taken during the PPV. Vitreous and serum levels of NSE, S100B and MDA were measured, and comparisons were made between the groups.

RESULTS

The study group consisted of 56 eyes of 56 cases with PDR. The control group consisted of 20 eyes of 20 cases. The concentrations of vitreous NSE, S100B and MDA were significantly higher than the control group (p < 0.0001, p < 0.05, p < 0.001, respectively). Serum levels were statistically different for NSE and S100B (p < 0.05).

CONCLUSION

Our results clearly show that vitreous levels of S100B, NSE and MDA and serum concentrations of NSE and S100B increased significantly in patients with PDR. The findings may possibly indicate neurodegeneration and oxidative stress; therefore, these markers may have a diagnostic value in patients with PDR.

MR Spectroscopy of the Cervical Spinal Cord in Chronic Spinal Cord Injury

Purpose To investigate metabolic changes in chronic spinal cord injury (SCI) by applying MR spectroscopy in the cervical spinal cord. Materials and Methods Single-voxel short-echo spectroscopic data in study participants with chronic SCI and healthy control subjects were prospectively acquired in the cervical spinal cord at C2 above the level of injury between March 2016 and January 2017 and were compared between groups. Concentrations of total N-acetylaspartate (tNAA), myo-inositol (mI), total choline-containing compounds (tCho), creatine, and glutamine and glutamate complex were estimated from the acquired spectra. Participants were assessed with a comprehensive clinical evaluation investigating sensory and motor deficits. Correlation analysis was applied to investigate relationships between observed metabolic differences, lesion severity, and clinical outcome. Results There were 18 male study participants with chronic SCI (median age, 51 years; range, 30-68 years) and 11 male healthy control subjects (median age, 45 years; range, 30-67 years). At cervical level C2, tNAA/mI and tCho/mI ratios were lower in participants with SCI (tNAA/mI: -26%, P = .003; tCho/mI: -18%; P = .04) than in healthy control subjects. The magnitude of difference was greater with the severity of cord atrophy (tNAA/mI: R² = 0.44, P = .003; tCho/mI: R² = 0.166, P = .09). Smaller tissue bridges at the lesion site correlated with lower ratios of tNAA/mI (R² = 0.69, P = .006) and tCho/mI (R² = 0.51, P = .03) at the C2 level. Lower tNAA/mI and tCho/mI ratios were associated with worse sensory and motor outcomes (P < .05). Conclusion Supralesional metabolic alterations are observed in chronic spinal cord injury, likely reflecting neurodegeneration, demyelination, and astrocytic gliosis in the injured cervical cord. Lesion severity and greater clinical impairment are both linked to the biochemical changes in the atrophied cervical cord after spinal cord injury. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Lin in this issue.

New Insights into the Role of Neuron-Specific Enolase in Neuro-Inflammation, Neurodegeneration, and Neuroprotection

Neurodegeneration is a complex process that leads to irreversible neuronal damage and death in spinal cord injury (SCI) and various neurodegenerative diseases, which are serious, debilitating conditions. Despite exhaustive research, the cause of neuronal damage in these degenerative disorders is not completely understood. Elevation of cell surface α-enolase activates various inflammatory pathways, including the production of pro-inflammatory cytokines, chemokines, and some growth factors that are detrimental to neuronal cells. While α-enolase is present in all neurological tissues, it can also be converted to neuron specific enolase (NSE). NSE is a glycolytic enzyme found in neuronal and neuroendocrine tissues that may play a dual role in promoting both neuroinflammation and neuroprotection in SCI and other neurodegenerative events. Elevated NSE can promote ECM degradation, inflammatory glial cell proliferation, and actin remodeling, thereby affecting migration of activated macrophages and microglia to the injury site and promoting neuronal cell death. Thus, NSE could be a reliable, quantitative, and specific marker of neuronal injury. Depending on the injury, disease, and microenvironment, NSE may also show neurotrophic function as it controls neuronal survival, differentiation, and neurite regeneration via activation of phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) signaling pathways. This review discusses possible implications of NSE expression and activity in neuroinflammation, neurodegeneration, and neuroprotection in SCI and various neurodegenerative diseases for prognostic and therapeutic potential.

Subject-specific regional measures of water diffusion are associated with impairment in chronic spinal cord injury

PURPOSE

We aimed to identify non-invasive imaging parameters that can serve as biomarkers for the integrity of the spinal cord, which is paramount to neurological function. Diffusion tensor imaging (DTI) indices are sensitive to axonal and myelin damage, and have strong potential to serve as such biomarkers. However, averaging DTI indices over large regions of interest (ROIs), a common approach to analyzing the images of injured spinal cord, leads to loss of subject-specific information. We investigated if DTI-tractography-driven, subject-specific demarcation approach can yield measures that are more specific to impairment.

METHODS

In 18 individuals with chronic spinal cord injury (SCI), subject-specific demarcation of the injury region was performed using DTI tractography, which yielded three regions relative to injury (RRI; regions superior to, at, and below injury epicenter). DTI indices averaged over each RRI were correlated with measures of residual motor and sensory function, obtained using the International Standard of Neurological Classification for Spinal Cord Injury (ISNCSCI).

RESULTS

Total ISNCSCI score (ISNCSCI-tot; sum of ISNCSCI motor and sensory scores) was significantly (p < 0.05) correlated with fractional anisotropy and axial and radial diffusivities. ISNCSCI-tot showed strongest correlation with indices measured from the region inferior to the injury epicenter (IRRI), the degree of which exceeded that of those measured from the entire cervical cord-suggesting contribution from Wallerian degeneration.

CONCLUSION

DTI tractography-driven, subject-specific injury demarcation approach provided measures that were more specific to impairment. Notably, DTI indices obtained from the IRRI region showed the highest specificity to impairment, demonstrating their strong potential as biomarkers for the SCI severity.

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.

Prediction of Neurological Impairment in Cervical Spondylotic Myelopathy using a Combination of Diffusion MRI and Proton MR Spectroscopy

PURPOSE

In the present study we investigated a combination of diffusion tensor imaging (DTI) and magnetic resonance spectroscopic (MRS) biomarkers in order to predict neurological impairment in patients with cervical spondylosis.

METHODS

Twenty-seven patients with cervical spondylosis were evaluated. DTI and single voxel MRS were performed in the cervical cord. N-acetylaspartate (NAA) and choline (Cho) metabolite concentration ratios with respect to creatine were quantified, as well as the ratio of choline to NAA. The modified mJOA scale was used as a measure of neurologic deficit. Linear regression was performed between DTI and MRS parameters and mJOA scores. Significant predictors from linear regression were used in a multiple linear regression model in order to improve prediction of mJOA. Parameters that did not add value to model performance were removed, then an optimized multiparametric model was established to predict mJOA.

RESULTS

Significant correlations were observed between the Torg-Pavlov ratio and FA (R2 = 0.2021, P = 0.019); DTI fiber tract density and FA, MD, Cho/NAA (R2 = 0.3412, P = 0.0014; R2 = 0.2112, P = 0.016; and R2 = 0.2352, P = 0.010 respectively); along with FA and Cho/NAA (R2 = 0.1695, P = 0.033). DTI fiber tract density, MD and FA at the site of compression, along with Cho/NAA at C2, were significantly correlated with mJOA score (R2 = 0.05939, P < 0.0001; R2 = 0.4739, P < 0.0001; R2 = 0.7034, P < 0.0001; R2 = 0.4649, P < 0.0001). A combination biomarker consisting of DTI fiber tract density, MD, and Cho/NAA showed the best prediction of mJOA (R2 = 0.8274, P<0.0001), with post-hoc tests suggesting fiber tract density, MD, and Cho/NAA were all significant contributors to predicting mJOA (P = 0.00053, P = 0.00085, and P = 0.0019, respectively).

CONCLUSION

A linear combination of DTI and MRS measurements within the cervical spinal cord may be useful for accurately predicting neurological deficits in patients with cervical spondylosis. Additional studies may be necessary to validate these observations.

A single dose of a neuron-binding human monoclonal antibody improves brainstem NAA concentrations, a biomarker for density of spinal cord axons, in a model of progressive multiple sclerosis

BACKGROUND

Intracerebral infection of susceptible mouse strains with Theiler's murine encephalomyelitis virus (TMEV) results in chronic demyelinating disease with progressive axonal loss and neurologic dysfunction similar to progressive forms of multiple sclerosis (MS). We previously showed that as the disease progresses, a marked decrease in brainstem N-acetyl aspartate (NAA; metabolite associated with neuronal integrity) concentrations, reflecting axon health, is measured. We also demonstrated stimulation of neurite outgrowth by a neuron-binding natural human antibody, IgM12. Treatment with either the serum-derived or recombinant human immunoglobulin M 12 (HIgM12) preserved functional motor activity in the TMEV model. In this study, we examined IgM-mediated changes in brainstem NAA concentrations and central nervous system (CNS) pathology.

FINDINGS

(1)H-magnetic resonance spectroscopy (MRS) showed that treatment with HIgM12 significantly increased brainstem NAA concentrations compared to controls in TMEV-infected mice. Pathologic analysis demonstrated a significant preservation of axons in the spinal cord of animals treated with HIgM12.

CONCLUSIONS

This study links drug efficacy of slowing deficits with axon preservation and NAA concentrations in the brainstem in a model of progressive MS. HIgM12-mediated changes of NAA concentrations in the brainstem are a surrogate marker of axon injury/preservation throughout the spinal cord. This study provides proof-of-concept that a neuron-reactive human IgM can be therapeutic and provides a biomarker for clinical trials.

Metabolic characterization of all-trans-retinoic acid (ATRA)-induced craniofacial development of murine embryos using in vivo proton magnetic resonance spectroscopy

AIM

To characterize the abnormal metabolic profile of all-trans-retinoic acid (ATRA)-induced craniofacial development in mouse embryos using proton magnetic resonance spectroscopy (1H-MRS).

METHODS

Timed-pregnant mice were treated by oral gavage on the morning of embryonic gestation day 11 (E11) with all-trans-retinoic acid (ATRA). Dosing solutions were adjusted by maternal body weight to provide 30, 70, or 100 mg/kg RA. The control group was given an equivalent volume of the carrier alone. Using an Agilent 7.0 T MR system and a combination of surface coil coils, a 3 mm×3 mm×3 mm 1H-MRS voxel was selected along the embryonic craniofacial tissue. 1H-MRS was performed with a single-voxel method using PRESS sequence and analyzed using LCModel software. Hematoxylin and eosin was used to detect and confirm cleft palate.

RESULT

1H-MRS revealed elevated choline levels in embryonic craniofacial tissue in the RA70 and RA100 groups compared to controls (P<0.05). Increased choline levels were also found in the RA70 and RA100 groups compared with the RA30 group (P<0.01). High intra-myocellular lipids at 1.30 ppm (IMCL13) in the RA100 group compared to the RA30 group were found (P<0.01). There were no significant changes in taurine, intra-myocellular lipids at 2.10 ppm (IMCL21), and extra-myocellular lipids at 2.30 ppm (EMCL23). Cleft palate formation was observed in all fetuses carried by mice administered 70 and 100 mg/kg RA.

CONCLUSIONS

This novel study suggests that the elevated choline and lipid levels found by 1H-MRS may represent early biomarkers of craniofacial defects. Further studies will determine performance of this test and pathogenetic mechanisms of craniofacial malformation.

Detection of endogenous iron deposits in the injured mouse spinal cord through high-resolution ex vivo and in vivo MRI

The main aim of this study was to employ high-resolution MRI to investigate the spatiotemporal development of pathological features associated with contusive spinal cord injury (SCI) in mice. Experimental mice were subjected to either sham surgery or moderate contusive SCI. A 16.4-T small-animal MR system was employed for nondestructive imaging of post-mortem, fixed spinal cord specimens at the subacute (7 days) and more chronic (28-35 days) stages post-injury. Routine histological techniques were used for subsequent investigation of the observed neuropathology at the microscopic level. The central core of the lesion appeared as a dark hypo-intense area on MR images at all time points investigated. Small focal hypo-intense spots were also observed spreading through the dorsal funiculi proximal and distal to the site of impact, an area that is known to undergo gliosis and Wallerian degeneration in response to injury. Histological examination revealed these hypo-intense spots to be high in iron content as determined by Prussian blue staining. Quantitative image analysis confirmed the increased presence of iron deposits at all post-injury time points investigated (p<0.05). Distant iron deposits were also detectable through live imaging without the use of contrast-enhancing agents, enabling the longitudinal investigation of this pathology in individual animals. Further immunohistochemical evaluation showed that intracellular iron deposits localised to macrophages/microglia, astrocytes and oligodendrocytes in the subacute phase of SCI, but predominantly to glial fibrillary acidic protein-positive, CC-1-positive astrocytes at later stages of recovery. Progressive, widespread intracellular iron accumulation is thus a normal feature of SCI in mice, and high-resolution MRI can be effectively used to detect and monitor these neuropathological changes with time.

Imaging techniques in spinal cord injury

BACKGROUND

Spinal imaging plays a critical role in the diagnosis, treatment, and rehabilitation of patients with spinal cord injury (SCI). In recent years there has been increasing interest in the development of advanced imaging techniques to provide pertinent microstructural and metabolic information that is not provided by conventional modalities.

METHODS

This review details the pathophysiological structural changes that accompany SCI, as well as their imaging correlates. The potential clinical applications of novel spinal cord imaging techniques to SCI are presented.

RESULTS

There are a variety of novel advanced imaging techniques that are principally focused on the microstructural and/or biochemical function of the spinal cord, and can potentially be applied to traumatic SCI, including diffusion tensor imaging, magnetic resonance spectroscopy, positron emission tomography, single-photon emission computed tomography, and functional magnetic resonance imaging. These techniques are presently in various stages of development, including some whose applications are primarily limited to laboratory investigation, whereas others are being actively used in clinical practice.

CONCLUSION

Advanced imaging of the spinal cord has tremendous potential to provide patient-specific physiological information about the status of cord integrity and health. Advanced spinal cord imaging is still at early stages of development and clinical implementation but is likely to play an increasingly important role in the management of spinal cord health in the foreseeable future.

Effect of acupuncture therapy for postponing Wallerian degeneration of cerebral infarction as shown by diffusion tensor imaging

OBJECTIVE

One aim of this study was to investigate the effects of acupuncture on cerebral function of patients with acute cerebral infarction. Another goal was to evaluate the relationship between acupuncture treatment and motor recovery patients with stroke and to provide a foundation for using acupuncture therapy for such patients.

DESIGN

Twenty (20) patients with recent cerebral infarction were divided randomly to an acupuncture group and a control group. The infarction area in each patient was in the basal ganglia or included the basal ganglia with an area size of > 1 cm(2). Serial diffusion tensor imaging (DTI), fluid-attenuated inversion recovery (FLAIR), and T2-weighted imaging (T(2)WI) scans were performed on all patients and the results were evaluated using the National Institute of Health Stroke Scale and the Barthel Index each week. DTI images were postprocessed and analyzed. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values of abnormal signals on DTI in the infarction areas and cerebral peduncles were calculated for both groups and compared with one another.

RESULTS

(1) The ADC value of infarction lesions decreased at stroke onset; then, a significant elevation was observed after the acute stage, and a significant reduction in FA values was observed from stroke onset to the chronic stage. (2) The ADC of the bilateral cerebral peduncle was reduced on the infarction side. (3) There was a significant difference in ADC and FA values between the acupuncture and control groups. The FA value was higher in the acupuncture group than the control group.

CONCLUSIONS

ADC and FA values might correlate to patient recovery and reveal the progress of secondary degeneration. Acupuncture treatment is effective for protecting neurons and facilitating recovery.

Metabolite profiles correlate closely with neurobehavioral function in experimental spinal cord injury in rats

Traumatic spinal cord injury (SCI) results in direct physical damage and the generation of local factors contributing to secondary pathogenesis. Untargeted metabolomic profiling was used to uncover metabolic changes and to identify relationships between metabolites and neurobehavioral functions in the spinal cord after injury in rats. In the early metabolic phase, neuronal signaling, stress, and inflammation-associated metabolites were strongly altered. A dynamic inflammatory response consisting of elevated levels of prostaglandin E2 and palmitoyl ethanolamide as well as pro- and anti-inflammatory polyunsaturated fatty acids was observed. N-acetyl-aspartyl-glutamate (NAAG) and N-acetyl-aspartate (NAA) were significantly decreased possibly reflecting neuronal cell death. A second metabolic phase was also seen, consistent with membrane remodeling and antioxidant defense response. These metabolomic changes were consistent with the pathology and progression of SCI. Several metabolites, including NAA, NAAG, and the ω-3 fatty acids docosapentaenoate and docosahexaenoate correlated greatly with the established Basso, Beattie and Bresnahan locomotive score (BBB score). Our findings suggest the possibility of a biochemical basis for BBB score and illustrate that metabolites may correlate with neurobehavior. In particular the NAA level in the spinal cord might provide a meaningful biomarker that could help to determine the degree of injury severity and prognosticate neurologic recovery.

Syndromics: a bioinformatics approach for neurotrauma research

Substantial scientific progress has been made in the past 50 years in delineating many of the biological mechanisms involved in the primary and secondary injuries following trauma to the spinal cord and brain. These advances have highlighted numerous potential therapeutic approaches that may help restore function after injury. Despite these advances, bench-to-bedside translation has remained elusive. Translational testing of novel therapies requires standardized measures of function for comparison across different laboratories, paradigms, and species. Although numerous functional assessments have been developed in animal models, it remains unclear how to best integrate this information to describe the complete translational "syndrome" produced by neurotrauma. The present paper describes a multivariate statistical framework for integrating diverse neurotrauma data and reviews the few papers to date that have taken an information-intensive approach for basic neurotrauma research. We argue that these papers can be described as the seminal works of a new field that we call "syndromics", which aim to apply informatics tools to disease models to characterize the full set of mechanistic inter-relationships from multi-scale data. In the future, centralized databases of raw neurotrauma data will enable better syndromic approaches and aid future translational research, leading to more efficient testing regimens and more clinically relevant findings.

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.

1H-MRS in spinal cord injury: acute and chronic metabolite alterations in rat brain and lumbar spinal cord

A variety of tests of sensorimotor function are used to characterize outcome after experimental spinal cord injury (SCI). These tests typically do not provide information about chemical and metabolic processes in the injured CNS. Here, we used (1) H-magnetic resonance spectroscopy (MRS) to monitor long-term and short-term chemical changes in the CNS in vivo following SCI. The investigated areas were cortex, thalamus/striatum and the spinal cord distal to injury. In cortex, glutamate (Glu) decreased 1 day after SCI and slowly returned towards normal levels. The combined glutamine (Gln) and Glu signal was similarly decreased in cortex, but increased in the distal spinal cord, suggesting opposite changes of the Glu/Gln metabolites in cortex and distal spinal cord. In lumbar spinal cord, a marked increase of myo-inositol was found 3 days, 14 days and 4 months after SCI. Changes in metabolite concentrations in the spinal cord were also found for choline and N-acetylaspartate. No significant changes in metabolite concentrations were found in thalamus/striatum. Multivariate data analysis allowed separation between rats with SCI and controls for spectra acquired in cortex and spinal cord, but not in thalamus/striatum. Our findings suggest MRS could become a helpful tool to monitor spatial and temporal alterations of metabolic conditions in vivo in the brain and spinal cord after SCI. We provide evidence for dynamic temporal changes at both ends of the neuraxis, cortex cerebri and distal spinal cord, while deep brain areas appear less affected.