Endothelial sulfonylurea receptor 1-regulated NC Ca-ATP channels mediate progressive hemorrhagic necrosis following spinal cord injury

Timed sulfonylurea modulation improves locomotor and sensory dysfunction following spinal cord injury

Traumatic spinal cord injury (SCI) results in immediate tissue necrosis and delayed secondary expansion of neurological damage, often resulting in lifelong paralysis, neurosensory dysfunction, and chronic pain. Progressive hemorrhagic necrosis (PHN) and excessive excitation are the main sources of secondary neural injury. Recent approaches to attenuate PHN by glibenclamide can improve locomotor function after SCI. However, use of glibenclamide can exacerbate development of SCI-induced chronic pain by inhibiting KATP channels to increase neuronal excitation and glial activation. In this study, we explored a treatment strategy involving administration of glibenclamide, which suppresses PHN, and diazoxide, which protects against neuronal excitation and inflammation, at different time intervals following spinal cord contusion. Our goal was to determine whether this combined approach enhances both sensory and motor function. Contusive SCI was induced at spinal segment T10 in adult rats. We found that KATP channels opener, diazoxide, decreased the hyperexcitability of primary sensory neurons after SCI by electrophysiology. Timed application of glibenclamide and diazoxide following contusion significantly improved locomotor function and mitigated development of SCI-induced chronic pain, as shown by behavioral evidence. Finally, we found that timed application of glibenclamide and diazoxide attenuates the inflammatory activity in the spinal cord and increases the survival of spinal matters following SCI. These preclinical studies introduce a promising potential treatment strategy to address SCI-induced dysfunction.

Management of traumatic spinal cord injury: A current concepts review of contemporary and future treatment

Spinal Cord Injury (SCI) is a condition leading to inflammation, edema, and dysfunction of the spinal cord, most commonly due to trauma, tumor, infection, or vascular disturbance. Symptoms include sensory and motor loss starting at the level of injury; the extent of damage depends on injury severity as detailed in the ASIA score. In the acute setting, maintaining mean arterial pressure (MAP) higher than 85 mmHg for up to 7 days following injury is preferred; although caution must be exercised when using vasopressors such as phenylephrine due to serious side effects such as pulmonary edema and death. Decompression surgery (DS) may theoretically relieve edema and reduce intraspinal pressure, although timing of surgery remains a matter of debate. Methylprednisolone (MP) is currently used due to its ability to reduce inflammation but more recent studies question its clinical benefits, especially with inconsistency in recommending it nationally and internationally. The choice of MP is further complicated by conflicting evidence for optimal timing to initiate treatment, and by the reported observation that higher doses are correlated with increased risk of complications. Thyrotropin-releasing hormone may be beneficial in less severe injuries. Finally, this review discusses many options currently being researched and have shown promising pre-clinical results.

Quantifying injury expansion in the cervical spinal cord with intravital ultrafast contrast-enhanced ultrasound imaging

Spinal cord injury is characterized by hemodynamic disruption at the injury epicenter and hypoperfusion in the penumbra, resulting in progressive ischemia and cell death. This degenerative secondary injury process has been well-described, though mostly using ex vivo or depth-limited optical imaging techniques. Intravital contrast-enhanced ultrasound enables longitudinal, quantitative evaluation of anatomical and hemodynamic changes in vivo through the entire spinal parenchyma. Here, we used ultrasound imaging to visualize and quantify subacute injury expansion (through 72 h post-injury) in a rodent cervical contusion model. Significant intraparenchymal hematoma expansion was observed through 72 h post-injury (1.86 ± 0.17-fold change from acute, p < 0.05), while the volume of the ischemic deficit largely increased within 24 h post-injury (2.24 ± 0.27-fold, p < 0.05). Histology corroborated these findings; increased apoptosis, tissue and vessel loss, and sustained tissue hypoxia were observed at 72 h post-injury. Vascular resistance was significantly elevated in the remaining perfused tissue, likely due in part to deformation of the central sulcal artery nearest to the lesion site. In conjunction, substantial hyperemia was observed in all perilesional areas examined except the ipsilesional gray matter. This study demonstrates the utility of longitudinal ultrasound imaging as a quantitative tool for tracking injury progression in vivo.

Protection of the Vascular System by Polyethylene Glycol Reduces Secondary Injury Following Spinal Cord Injury in Rats

BACKGROUND

Polyethylene glycol (PEG) is a hydrophilic polymer, which has been known to have a neuroprotective effect by sealing the ruptured cell membrane, but PEG effects on the vascular systems and its underlying mechanisms remain unclear. Here, we showed the neuroprotective effect of PEG by preventing damage to the vascular system.

METHODS

A spinal contusion was made at the T11 segment in male Sprague-Dawley rats. PEG was injected into the subdural space immediately after SCI. Vascular permeability was assessed for 24 h after SCI using intraperitoneally injected Evans blue dye. Junctional complexes were stained with CD31 and ZO-1. Infarct size was analyzed using triphenyltetrazolium chloride, and blood vessels were counted in the epicenter. Behavioral tests for motor and sensory function were performed for 6 weeks. And then the tissue-sparing area was assessed.

RESULTS

Immediately applied PEG significantly reduced the vascular permeability at 6, 12, and 24 h after SCI when it compared to saline, and infarct size was also reduced at 0, 6, and 24 h after SCI. In addition, a great number of blood vessels were observed in PEG group at 6 and 24 h after SCI compared to those of the saline group. The PEG group also showed a significant improvement in motor function. And tissue-sparing areas in the PEG were greater than those of the saline group.

CONCLUSION

The present results provide preclinical evidence for the neuroprotective effects of PEG as a promising therapeutic agent for reducing secondary injury following SCI through vascular protection.

Different Ways to Die: Cell Death Pathways and Their Association With Spinal Cord Injury

Cell death is a systematic/nonsystematic process of cessation of normal morphology and functional properties of the cell to replace and recycle old cells with new also promoting inflammation in some cases. It is a complicated process comprising multiple pathways. Some are well-explored, and others have just begun to be. The research on appropriate control of cell death pathways after acute and chronic damage of neuronal cells is being widely researched today due to the lack of regeneration and recovering potential of a neuronal cell after sustaining damage and the inability to control the direction of neuronal growth. In the progression and onset of various neurological diseases, impairments in programmed cell death signaling processes, like necroptosis, apoptosis, ferroptosis, pyroptosis, and pathways directly or indirectly linked, like autophagy as in nonprogrammed necrosis, are observed. Spinal cord injury (SCI) involves the temporary or permanent disruption of motor activities due to the death of a neuronal and glial cell in the spinal cord accompanied by axonal degeneration. Recent years have seen a significant increase in research on the intricate biochemical interactions that occur after a SCI. Different cell death pathways may significantly impact the subsequent damage processes that lead to the eventual neurological deficiency after an injury to the spinal cord. A better knowledge of the molecular basis of the involved cell death pathways might help enhance neuronal and glial survival and neurological deficits, promoting a curative path for SCI.

Mortality in ASIA Impairment Scale grade A to D Patients With Odontoid Fracture and Magnetic Resonance Imaging Evidence of Spinal Cord Injury

Odontoid fractures are common, often presenting in the elderly after a fall and infrequently associated with traumatic spinal cord injury (tSCI). The goal of this study was to analyze predictors of mortality and neurological outcome when odontoid fractures were associated with signal change on magnetic resonance imaging (MRI) at admission. Over an 18-year period (2001-2019), 33 patients with odontoid fractures and documented tSCI on MRI were identified. Mean age was 65.3 years (standard deviation [SD] = 17.2), and 21 patients were male. The mechanism of injury was falls in 25 patients, motor vehicle accidents in 5, and other causes in 3. Mean Injury Severity Score (ISS) was 40.5 (SD = 30.2), Glasgow Coma Scale (GCS) score was 13 (SD = 3.4), and American Spinal Injury Association (ASIA) motor score (AMS) was 51.6 (SD = 42.7). ASIA Impairment Scale (AIS) grade was A, B, C, and D in 9, 2, 3, and 19 patients, respectively. Mean intramedullary lesion length was 32.3 mm (SD = 18.6). The odontoid peg was displaced ventral or dorsal in 15 patients. Twenty patients had surgical intervention: anterior odontoid screw fixation in 7 and posterior spinal fusion in 13. Eleven (33.3%) patients died in this series: withdrawal of medical care in 5; anoxic brain injury in 4; and failure of critical care management in 2. Univariate logistic regression indicated that GCS score (p < 0.014), AMS (p < 0.002), AIS grade (p < 0.002), and ISS (p < 0.009) were risk factors for mortality. Multi-variate regression analysis indicated that only AMS (p < 0.002) had a significant relationship with mortality when odontoid fracture was associated with tSCI (odds ratio, 0.963; 95% confidence interval, 0.941-0.986).

Spatiotemporal microvascular changes following contusive spinal cord injury

Microvascular integrity is disrupted following spinal cord injury (SCI) by both primary and secondary insults. Changes to neuronal structures are well documented, but little is known about how the capillaries change and recover following injury. Spatiotemporal morphological information is required to explore potential treatments targeting the microvasculature post-SCI to improve functional recovery. Sprague-Dawley rats were given a T10 moderate/severe (200 kDyn) contusion injury and were perfuse-fixed at days 2, 5, 15, and 45 post-injury. Unbiased stereology following immunohistochemistry in four areas (ventral and dorsal grey and white matter) across seven spinal segments (n = 4 for each group) was used to calculate microvessel density, surface area, and areal density. In intact sham spinal cords, average microvessel density across the thoracic spinal cord was: ventral grey matter: 571 ± 45 mm-2, dorsal grey matter: 484 ± 33 mm-2, ventral white matter: 90 ± 8 mm-2, dorsal white matter: 88 ± 7 mm-2. Post-SCI, acute microvascular disruption was evident, particularly at the injury epicentre, and spreading three spinal segments rostrally and caudally. Damage was most severe in grey matter at the injury epicentre (T10) and T11. Reductions in all morphological parameters (95-99% at day 2 post-SCI) implied vessel regression and/or collapse acutely. Transmission electron microscopy (TEM) revealed disturbed aspects of neurovascular unit fine structure at day 2 post-SCI (n = 2 per group) at T10 and T11. TEM demonstrated a more diffuse and disrupted basement membrane and wider intercellular clefts at day 2, suggesting a more permeable blood spinal cord barrier and microvessel remodelling. Some evidence of angiogenesis was seen during recovery from days 2 to 45, indicated by increased vessel density, surface area, and areal density at day 45. These novel results show that the spinal cord microvasculature is highly adaptive following SCI, even at chronic stages and up to three spinal segments from the injury epicentre. Multiple measures of gross and fine capillary structure from acute to chronic time points provide insight into microvascular remodelling post-SCI. We have identified key vascular treatment targets, namely stabilising damaged capillaries and replacing destroyed vessels, which may be used to improve functional outcomes following SCI in the future.

The TRPM4 channel inhibitor 9-phenanthrol alleviates cerebral edema after traumatic brain injury in rats

Cerebral edema (CE) exerts an important effect on brain injury after traumatic brain injury (TBI). Upregulation of transient receptor potential melastatin 4 (TRPM4) in vascular endothelial cells (ECs) results in damage to capillaries and the blood-brain barrier (BBB), which is critical for the development of CE. Many studies have shown that 9-phenanthrol (9-PH) effectively inhibits TRPM4. The current study aimed to investigate the effect of 9-PH on reducing CE after TBI. In this experiment, we observed that 9-PH markedly reduced brain water content, BBB disruption, proliferation of microglia and astrocytes, neutrophil infiltration, neuronal apoptosis and neurobehavioral deficits. At the molecular level, 9-PH significantly inhibited the protein expression of TRPM4 and MMP-9, alleviated the expression of apoptosis-related molecules and inflammatory cytokines, such as Bax, TNF-α and IL-6, near injured tissue, and diminished serum SUR1 and TRPM4 levels. Mechanistically, treatment with 9-PH inhibited activation of the PI3K/AKT/NF-kB signaling pathway, which was reported to be involved in the expression of MMP-9. Taken together, the results of this study indicate that 9-PH effectively reduces CE and alleviates secondary brain injury partly through the following possible mechanisms: ①9-PH inhibits TRPM4-mediated Na + influx and reduces cytotoxic CE; ②9-PH hinders the expression and activity of MMP-9 by inhibiting the TRPM4 channel and decreases disruption of the BBB, thereby preventing vasogenic cerebral edema. ③9-PH reduces further inflammatory and apoptotic damage to tissues.

Clinical Trials Targeting Secondary Damage after Traumatic Spinal Cord Injury

Spinal cord injury (SCI) often causes loss of sensory and motor function resulting in a significant reduction in quality of life for patients. Currently, no therapies are available that can repair spinal cord tissue. After the primary SCI, an acute inflammatory response induces further tissue damage in a process known as secondary injury. Targeting secondary injury to prevent additional tissue damage during the acute and subacute phases of SCI represents a promising strategy to improve patient outcomes. Here, we review clinical trials of neuroprotective therapeutics expected to mitigate secondary injury, focusing primarily on those in the last decade. The strategies discussed are broadly categorized as acute-phase procedural/surgical interventions, systemically delivered pharmacological agents, and cell-based therapies. In addition, we summarize the potential for combinatorial therapies and considerations.

Abcc8 (sulfonylurea receptor-1) knockout mice exhibit reduced axonal injury, cytotoxic edema and cognitive dysfunction vs. wild-type in a cecal ligation and puncture model of sepsis

Sepsis-associated brain injury (SABI) is characterized by an acute deterioration of mental status resulting in cognitive impairment and acquisition of new and persistent functional limitations in sepsis survivors. Previously, we reported that septic mice had evidence of axonal injury, robust microglial activation, and cytotoxic edema in the cerebral cortex, thalamus, and hippocampus in the absence of blood-brain barrier disruption. A key conceptual advance in the field was identification of sulfonylurea receptor 1 (SUR1), a member of the adenosine triphosphate (ATP)-binding cassette protein superfamily, that associates with the transient receptor potential melastatin 4 (TRPM4) cation channel to play a crucial role in cerebral edema development. Therefore, we hypothesized that knockout (KO) of Abcc8 (Sur1 gene) is associated with a decrease in microglial activation, cerebral edema, and improved neurobehavioral outcomes in a murine cecal ligation and puncture (CLP) model of sepsis. Sepsis was induced in 4-6-week-old Abcc8 KO and wild-type (WT) littermate control male mice by CLP. We used immunohistochemistry to define neuropathology and microglial activation along with parallel studies using magnetic resonance imaging, focusing on cerebral edema on days 1 and 4 after CLP. Abcc8 KO mice exhibited a decrease in axonal injury and cytotoxic edema vs. WT on day 1. Abcc8 KO mice also had decreased microglial activation in the cerebral cortex vs. WT. These findings were associated with improved spatial memory on days 7-8 after CLP. Our study challenges a key concept in sepsis and suggests that brain injury may not occur merely as an extension of systemic inflammation. We advance the field further and demonstrate that deletion of the SUR1 gene ameliorates CNS pathobiology in sepsis including edema, axonal injury, neuroinflammation, and behavioral deficits. Benefits conferred by Abcc8 KO in the murine CLP model warrant studies of pharmacological Abcc8 inhibition as a new potential therapeutic strategy for SABI.

Molecular approaches for spinal cord injury treatment

Injuries to the spinal cord result in permanent disabilities that limit daily life activities. The main reasons for these poor outcomes are the limited regenerative capacity of central neurons and the inhibitory milieu that is established upon traumatic injuries. Despite decades of research, there is still no efficient treatment for spinal cord injury. Many strategies are tested in preclinical studies that focus on ameliorating the functional outcomes after spinal cord injury. Among these, molecular compounds are currently being used for neurological recovery, with promising results. These molecules target the axon collapsed growth cone, the inhibitory microenvironment, the survival of neurons and glial cells, and the re-establishment of lost connections. In this review we focused on molecules that are being used, either in preclinical or clinical studies, to treat spinal cord injuries, such as drugs, growth and neurotrophic factors, enzymes, and purines. The mechanisms of action of these molecules are discussed, considering traumatic spinal cord injury in rodents and humans.

Quantifying Intraparenchymal Hemorrhage after Traumatic Spinal Cord Injury: A Review of Methodology

Intraparenchymal hemorrhage (IPH) after a traumatic injury has been associated with poor neurological outcomes. Although IPH may result from the initial mechanical trauma, the blood and its breakdown products have potentially deleterious effects. Further, the degree of IPH has been correlated with injury severity and the extent of subsequent recovery. Therefore, accurate evaluation and quantification of IPH following traumatic spinal cord injury (SCI) is important to define treatments' effects on IPH progression and secondary neuronal injury. Imaging modalities, such as magnetic resonance imaging (MRI) and ultrasound (US), have been explored by researchers for the detection and quantification of IPH following SCI. Both quantitative and semiquantitative MRI and US measurements have been applied to objectively assess IPH following SCI, but the optimal methods for doing so are not well established. Studies in animal SCI models (rodent and porcine) have explored US and histological techniques in evaluating SCI and have demonstrated the potential to detect and quantify IPH. Newer techniques using machine learning algorithms (such as convolutional neural networks [CNN]) have also been studied to calculate IPH volume and have yielded promising results. Despite long-standing recognition of the potential pathological significance of IPH within the spinal cord, quantifying IPH with MRI or US is a relatively new area of research. Further studies are warranted to investigate their potential use. Here, we review the different and emerging quantitative MRI, US, and histological approaches used to detect and quantify IPH following SCI.

Pathophysiology and Therapeutic Approaches for Spinal Cord Injury

Spinal cord injury (SCI) is a disabling condition that disrupts motor, sensory, and autonomic functions. Despite extensive research in the last decades, SCI continues to be a global health priority affecting thousands of individuals every year. The lack of effective therapeutic strategies for patients with SCI reflects its complex pathophysiology that leads to the point of no return in its function repair and regeneration capacity. Recently, however, several studies started to uncover the intricate network of mechanisms involved in SCI leading to the development of new therapeutic approaches. In this work, we present a detailed description of the physiology and anatomy of the spinal cord and the pathophysiology of SCI. Additionally, we provide an overview of different molecular strategies that demonstrate promising potential in the modulation of the secondary injury events that promote neuroprotection or neuroregeneration. We also briefly discuss other emerging therapies, including cell-based therapies, biomaterials, and epidural electric stimulation. A successful therapy might target different pathologic events to control the progression of secondary damage of SCI and promote regeneration leading to functional recovery.

Glibenclamide Directly Prevents Neuroinflammation by Targeting SUR1-TRPM4-Mediated NLRP3 Inflammasome Activation In Microglia

Glibenclamide (GLB) reduces brain edema and improves neurological outcome in animal experiments and preliminary clinical studies. Recent studies also suggested a strong anti-inflammatory effect of GLB, via inhibiting nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasome activation. However, it remains unknown whether the anti-inflammatory effect of GLB is independent of its role in preventing brain edema, and how GLB inhibits the NLRP3 inflammasome is not fully understood. Sprague-Dawley male rats underwent 10-min asphyxial cardiac arrest and cardiopulmonary resuscitation or sham-operation. The Trpm4 siRNA and GLB were injected to block sulfonylurea receptor 1-transient receptor potential M4 (SUR1-TRPM4) channel in rats. Western blotting, quantitative real-time polymerase chain reaction, behavioral analysis, and histological examination were used to evaluate the role of GLB in preventing NLRP3-mediated neuroinflammation through inhibiting SUR1-TRPM4, and corresponding neuroprotective effect. To further explore the underlying mechanism, BV2 cells were subjected to lipopolysaccharides, or oxygen-glucose deprivation/reperfusion. Here, in rat model of cardiac arrest with brain edema combined with neuroinflammation, GLB significantly alleviated neurocognitive deficit and neuropathological damage, via the inhibition of microglial NLRP3 inflammasome activation by blocking SUR1-TRPM4. Of note, the above effects of GLB could be achieved by knockdown of Trpm4. In vitro under circumstance of eliminating distractions from brain edema, SUR1-TRPM4 and NLRP3 inflammasome were also activated in BV2 cells subjected to lipopolysaccharides, or oxygen-glucose deprivation/reperfusion, which could be blocked by GLB or 9-phenanthrol, a TRPM4 inhibitor. Importantly, activation of SUR1-TRPM4 in BV2 cells required the P2X7 receptor-mediated Ca2+ influx, which in turn magnified the K+ efflux via the Na+ influx-driven opening of K+ channels, leading to the NLRP3 inflammasome activation. These findings suggest that GLB has a direct anti-inflammatory neuroprotective effect independent of its role in preventing brain edema, through inhibition of SUR1-TRPM4 which amplifies K+ efflux and promotes NLRP3 inflammasome activation.

When should researchers cite study differences in response to a failure to replicate?

Scientists often respond to failures to replicate by citing differences between the experimental components of an original study and those of its attempted replication. In this paper, we investigate these purported mismatch explanations. We assess a body of failures to replicate in neuroscience studies on spinal cord injury. We argue that a defensible mismatch explanation is one where (1) a mismatch of components is a difference maker for a mismatch of outcomes, and (2) the components are relevantly different in the follow-up study, given the scope of the original study. With this account, we argue that not all differences between studies are meaningful, even if they are difference makers. As our examples show, focusing only on these differences results in disregarding the representativeness of the original experiment's components and the scope of its outcomes, undercutting other epistemic aims, such as translation, in the process.

A Direct Comparison of Physical Versus Dihydrocapsaicin-Induced Hypothermia in a Rat Model of Traumatic Spinal Cord Injury

Spinal cord injury (SCI) is a devastating neurological condition with no effective treatment. Hypothermia induced by physical means (cold fluid) is established as an effective therapy in animal models of SCI, but its clinical translation to humans is hampered by several constraints. Hypothermia induced pharmacologically may be noninferior or superior to physically induced hypothermia for rapid, convenient systemic temperature reduction, but it has not been investigated previously in animal models of SCI. We used a rat model of SCI to compare outcomes in three groups: (1) normothermic controls; (2) hypothermia induced by conventional physical means; (3) hypothermia induced by intravenous (IV) dihydrocapsaicin (DHC). Male rats underwent unilateral lower cervical SCI and were treated after a 4-hour delay with physical cooling or IV DHC (∼0.60 mg/kg total) cooling (both 33.0 ± 1.0°C) lasting 4 hours; controls were kept normothermic. Telemetry was used to monitor temperature and heart rate during and after treatments. In two separate experiments, one ending at 48 hours, the other at 6 weeks, “blinded” investigators evaluated rats in the three groups for neurological function followed by histopathological evaluation of spinal cord tissues. DHC reliably induced systemic cooling to 32–33°C. At both the time points examined, the two modes of hypothermia yielded similar improvements in neurological function and lesion size compared with normothermic controls. Our results indicate that DHC-induced hypothermia may be comparable with physical hypothermia in efficacy, but more clinically feasible to administer than physical hypothermia.

Glibenclamide promoted functional recovery following sciatic nerve injury in male Wistar rats

The impact of peripheral nerve damage on a patient's quality of life is severe. The most frequent peripheral nerve crush damage is a sciatic nerve injury. Previous research has shown that glibenclamide (GB) has neuroprotective properties in a variety of oxidative stress-related disorders, including Alzheimer and Parkinson. The goal of this study was to see how GB affected nerve regeneration and improved function of the sciatic nerve in a rat model following a crush injury. We evaluated motor function, sensory recovery, gene expression, and histomorphometry following damage at different time points. Additionally, we assessed atrophy in the gastrocnemius muscle using histology and mass ratio analyses. Our results suggest that 2, 4, 6, and 8 weeks following glibenclamide therapy, promotes the recovery of motor and sensory function in the injured site. Following glibenclamid injection, the mRNA levels of neurotrophic factors (NGF and BDNF) are raised. According to histomorphometry assessment, glibenclamide injection also increased the number of myelinated fibers while decreasing their thickness. These results showed that glibenclamide therapy by decreasing the proinflammatory and oxidant factors may enhance the nerve regeneration. It is clear that more research is needed to confirm these findings.

A glibenclamide-sensitive TRPM4-mediated component of CA1 excitatory postsynaptic potentials appears in experimental autoimmune encephalomyelitis

The transient receptor potential melastatin 4 (TRPM4) channel contributes to disease severity in the murine experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis and to neuronal cell death in models of excitotoxicity and traumatic brain injury. As TRPM4 is activated by intracellular calcium and conducts monovalent cations, we hypothesized that TRPM4 may contribute to and boost excitatory synaptic transmission in CA1 pyramidal neurons of the hippocampus. Using single-spine calcium imaging and electrophysiology, we found no effect of the TRPM4 antagonists 9-phenanthrol and glibenclamide on synaptic transmission in hippocampal slices from healthy mice. In contrast, glibenclamide but not 9-phenanthrol reduced excitatory synaptic potentials in slices from EAE mice, an effect that was absent in slices from EAE mice lacking TRPM4. We conclude that TRPM4 plays little role in basal hippocampal synaptic transmission, but a glibenclamide-sensitive TRPM4-mediated contribution to excitatory postsynaptic responses is upregulated at the acute phase of EAE.

Elevated intraspinal pressure in traumatic spinal cord injury is a promising therapeutic target

The currently recommended management for acute traumatic spinal cord injury aims to reduce the incidence of secondary injury and promote functional recovery. Elevated intraspinal pressure (ISP) likely plays an important role in the processes involved in secondary spinal cord injury, and should not be overlooked. However, the factors and detailed time course contributing to elevated ISP and its impact on pathophysiology after traumatic spinal cord injury have not been reviewed in the literature. Here, we review the etiology and progression of elevated ISP, as well as potential therapeutic measures that target elevated ISP. Elevated ISP is a time-dependent process that is mainly caused by hemorrhage, edema, and blood-spinal cord barrier destruction and peaks at 3 days after traumatic spinal cord injury. Duraplasty and hypertonic saline may be promising treatments for reducing ISP within this time window. Other potential treatments such as decompression, spinal cord incision, hemostasis, and methylprednisolone treatment require further validation.

Sodium tanshinone IIA sulfonate promotes spinal cord injury repair by inhibiting blood spinal cord barrier disruption in vitro and in vivo

Spinal cord injury (SCI) leads to microvascular damage and the destruction of the blood spinal cord barrier (BSCB), which can progress into secondary injuries, such as apoptosis and necrosis of neurons and glia, culminating in permanent neurological deficits. BSCB restoration is the primary goal of SCI therapy, although very few drugs can repair damaged barrier structure and permeability. Sodium tanshinone IIA sulfonate (STS) is commonly used to treat cardiovascular disease. However, the therapeutic effects of STS on damaged BSCB during the early stage of SCI remain uncertain. Therefore, we exposed spinal cord microvascular endothelial cells to H₂ O₂ and treated them with different doses of STS. In addition to protecting the cells from H₂ O₂ -induced apoptosis, STS also reduced cellular permeability. In the in vivo model of SCI, STS reduced BSCB permeability, relieved tissue edema and hemorrhage, suppressed MMP activation and prevented the loss of tight junction and adherens junction proteins. Our findings indicate that STS treatment promotes SCI recovery, and should be investigated further as a drug candidate against traumatic SCI.

Sulfonylurea Receptor 1 in Central Nervous System Injury: An Updated Review

Sulfonylurea receptor 1 (SUR1) is a member of the adenosine triphosphate (ATP)-binding cassette (ABC) protein superfamily, encoded by Abcc8, and is recognized as a key mediator of central nervous system (CNS) cellular swelling via the transient receptor potential melastatin 4 (TRPM4) channel. Discovered approximately 20 years ago, this channel is normally absent in the CNS but is transcriptionally upregulated after CNS injury. A comprehensive review on the pathophysiology and role of SUR1 in the CNS was published in 2012. Since then, the breadth and depth of understanding of the involvement of this channel in secondary injury has undergone exponential growth: SUR1-TRPM4 inhibition has been shown to decrease cerebral edema and hemorrhage progression in multiple preclinical models as well as in early clinical studies across a range of CNS diseases including ischemic stroke, traumatic brain injury, cardiac arrest, subarachnoid hemorrhage, spinal cord injury, intracerebral hemorrhage, multiple sclerosis, encephalitis, neuromalignancies, pain, liver failure, status epilepticus, retinopathies and HIV-associated neurocognitive disorder. Given these substantial developments, combined with the timeliness of ongoing clinical trials of SUR1 inhibition, now, another decade later, we review advances pertaining to SUR1-TRPM4 pathobiology in this spectrum of CNS disease-providing an overview of the journey from patch-clamp experiments to phase III trials.

Emerging therapeutic targets for cerebral edema

INTRODUCTION

Cerebral edema is a key contributor to death and disability in several forms of brain injury. Current treatment options are limited, reactive, and associated with significant morbidity. Targeted therapies are emerging based on a growing understanding of the molecular underpinnings of cerebral edema.

AREAS COVERED

We review the pathophysiology and relationships between different cerebral edema subtypes to provide a foundation for emerging therapies. Mechanisms for promising molecular targets are discussed, with an emphasis on those advancing in clinical trials, including ion and water channels (AQP4, SUR1-TRPM4) and other proteins/lipids involved in edema signaling pathways (AVP, COX2, VEGF, and S1P). Research on novel treatment modalities for cerebral edema [including recombinant proteins and gene therapies] is presented and finally, insights on reducing secondary injury and improving clinical outcome are offered.

EXPERT OPINION

Targeted molecular strategies to minimize or prevent cerebral edema are promising. Inhibition of SUR1-TRPM4 (glyburide/glibenclamide) and VEGF (bevacizumab) are currently closest to translation based on advances in clinical trials. However, the latter, tested in glioblastoma multiforme, has not demonstrated survival benefit. Research on recombinant proteins and gene therapies for cerebral edema is in its infancy, but early results are encouraging. These newer modalities may facilitate our understanding of the pathobiology underlying cerebral edema.

The Restorative Effect of Human Amniotic Fluid Stem Cells on Spinal Cord Injury

Spinal cord injury (SCI) is a debilitating condition within the neural system which is clinically manifested by sensory-motor dysfunction, leading, in some cases, to neural paralysis for the rest of the patient’s life. In the current study, mesenchymal stem cells (MSCs) were isolated from the human amniotic fluid, in order to study their juxtacrine and paracrine activities. Flow cytometry analysis was performed to identify the MSCs. A conditioned medium (CM) was collected to measure the level of BDNF, IL-1β, and IL-6 proteins using the ELISA assay. Following the SCI induction, MSCs and CM were injected into the lesion site, and also CM was infused intraperitoneally in the different groups. Two weeks after SCI induction, the spinal cord samples were examined to evaluate the expression of the doublecortin (DCX) and glial fibrillary acid protein (GFAP) markers using immunofluorescence staining. The MSCs’ phenotype was confirmed upon the expression and un-expression of the related CD markers. Our results show that MSCs increased the expression level of the DCX and decreased the level of the GFAP relative to the injury group (p < 0.001). Additionally, the CM promoted the DCX expression rate (p < 0.001) and decreased the GFAP expression rate (p < 0.01) as compared with the injury group. Noteworthily, the restorative potential of the MSCs was higher than that of the CM (p < 0.01). Large-scale meta-analysis of transcriptomic data highlighted PAK5, ST8SIA3, and NRXN1 as positively coexpressed genes with DCX. These genes are involved in neuroactive ligand–receptor interaction. Overall, our data revealed that both therapeutic interventions could promote the regeneration and restoration of the damaged neural tissue by increasing the rate of neuroblasts and decreasing the astrocytes.

Research advances of biomaterials-based microenvironment-regulation therapies for repair and regeneration of spinal cord injury

Traumatic spinal cord injury (SCI) usually results in restricted behaviour recovery and even life-changing paralysis, accompanied with numerous complications. Pathologically, the initial injuries trigger a series of secondary injuries, leading to an expansion of lesion site, a mass of neuron loss, and eventual failure of endogenous axon regeneration. As the advances rapidly spring up in regenerative medicine and tissue engineering biomaterials, regulation of these secondary injuries becomes possible, shedding a light on normal functional restoration. The successful tissue regeneration lies in proper regulation of the inflammatory microenvironment, including the inflammatory immune cells and inflammatory factors that lead to oxidative stress, inhibitory glial scar and neuroexcitatory toxicity. Specifically, the approaches based on microenvironment-regulating biomaterials have shown great promise in the repair and regeneration of SCI. In this review, the pathological inflammatory microenvironments of SCI are discussed, followed by the introduction of microenvironment-regulating biomaterials in terms of their impressive therapeutic effect in attenuation of secondary inflammation and promotion of axon regrowth. With the emphasis on regulating secondary events, the biomaterials for SCI treatment will become promising for clinical applications.

Acute spinal cord injury: Pathophysiology and pharmacological intervention (Review)

Spinal cord injury (SCI) is one of the most debilitating of all the traumatic conditions that afflict individuals. For a number of years, extensive studies have been conducted to clarify the molecular mechanisms of SCI. Experimental and clinical studies have indicated that two phases, primary damage and secondary damage, are involved in SCI. The initial mechanical damage is caused by local impairment of the spinal cord. In addition, the fundamental mechanisms are associated with hyperflexion, hyperextension, axial loading and rotation. By contrast, secondary injury mechanisms are led by systemic and cellular factors, which may also be initiated by the primary injury. Although significant advances in supportive care have improved clinical outcomes in recent years, a number of studies continue to explore specific pharmacological therapies to minimize SCI. The present review summarized some important pathophysiologic mechanisms that are involved in SCI and focused on several pharmacological and non‑pharmacological therapies, which have either been previously investigated or have a potential in the management of this debilitating injury in the near future.

BAPTA, a calcium chelator, neuroprotects injured neurons in vitro and promotes motor recovery after spinal cord transection in vivo

Aim

Despite animal evidence of a role of calcium in the pathogenesis of spinal cord injury, several studies conducted in the past found calcium blockade ineffective. However, those studies involved oral or parenteral administration of Ca++ antagonists. We hypothesized that Ca++ blockade might be effective with local/immediate application (LIA) at the time of neural injury.

Methods

In this study, we assessed the effects of LIA of BAPTA (1,2‐bis (o‐aminophenoxy) ethane‐N, N, N′, N'‐tetraacetic acid), a cell‐permeable highly selective Ca++ chelator, after spinal cord transection (SCT) in mice over 4 weeks. Effects of BAPTA were assessed behaviorally and with immunohistochemistry. Concurrently, BAPTA was submitted for the first time to multimodality assessment in an in vitro model of neural damage as a possible spinal neuroprotectant.

Results

We demonstrate that BAPTA alleviates neuronal apoptosis caused by physical damage by inhibition of neuronal apoptosis and reactive oxygen species (ROS) generation. This translates to enhanced preservation of electrophysiological function and superior behavioral recovery.

Conclusion

This study shows for the first time that local/immediate application of Ca++ chelator BAPTA is strongly neuroprotective after severe spinal cord injury.

Meeting Proceedings for SCI 2020: Launching a Decade of Disruption in Spinal Cord Injury Research

The spinal cord injury (SCI) research community has experienced great advances in discovery research, technology development, and promising clinical interventions in the past decade. To build upon these advances and maximize the benefit to persons with SCI, the National Institutes of Health (NIH) hosted a conference February 12-13, 2019 titled "SCI 2020: Launching a Decade of Disruption in Spinal Cord Injury Research." The purpose of the conference was to bring together a broad range of stakeholders, including researchers, clinicians and healthcare professionals, persons with SCI, industry partners, regulators, and funding agency representatives to break down existing communication silos. Invited speakers were asked to summarize the state of the science, assess areas of technological and community readiness, and build collaborations that could change the trajectory of research and clinical options for people with SCI. In this report, we summarize the state of the science in each of five key domains and identify the gaps in the scientific literature that need to be addressed to move the field forward.

Efficacy of Early (≤ 24 Hours), Late (25-72 Hours), and Delayed (>72 Hours) Surgery with Magnetic Resonance Imaging-Confirmed Decompression in American Spinal Injury Association Impairment Scale Grades C and D Acute Traumatic Central Cord Syndrome Caused by Spinal Stenosis

The therapeutic significance of timing of decompression in acute traumatic central cord syndrome (ATCCS) caused by spinal stenosis remains unsettled. We retrospectively examined a homogenous cohort of patients with ATCCS and magnetic resonance imaging (MRI) evidence of post-treatment spinal cord decompression to determine whether timing of decompression played a significant role in American Spinal Injury Association (ASIA) motor score (AMS) 6 months following trauma. We used the t test, analysis of variance, Pearson correlation coefficient, and multiple regression for statistical analysis. During a 19-year period, 101 patients with ATCCS, admission ASIA Impairment Scale (AIS) grades C and D, and an admission AMS of ≤95 were surgically decompressed. Twenty-four of 101 patients had an AIS grade C injury. Eighty-two patients were males, the mean age of patients was 57.9 years, and 69 patients had had a fall. AMS at admission was 68.3 (standard deviation [SD] 23.4); upper extremities (UE) 28.6 (SD 14.7), and lower extremities (LE) 41.0 (SD 12.7). AMS at the latest follow-up was 93.1 (SD 12.8), UE 45.4 (SD 7.6), and LE 47.9 (SD 6.6). Mean number of stenotic segments was 2.8, mean canal compromise was 38.6% (SD 8.7%), and mean intramedullary lesion length (IMLL) was 23 mm (SD 11). Thirty-six of 101 patients had decompression within 24 h, 38 patients had decompression between 25 and 72 h, and 27 patients had decompression >72 h after injury. Demographics, etiology, AMS, AIS grade, morphometry, lesion length, surgical technique, steroid protocol, and follow-up AMS were not statistically different between groups treated at different times. We analyzed the effect size of timing of decompression categorically and in a continuous fashion. There was no significant effect of the timing of decompression on follow-up AMS. Only AMS at admission determined AMS at follow-up (coefficient = 0.31; 95% confidence interval [CI]:0.21; p = 0.001). We conclude that timing of decompression in ATCCS caused by spinal stenosis has little bearing on ultimate AMS at follow-up.

The antidiabetic drug glibenclamide exerts direct retinal neuroprotection

Sulfonylureas, widely used as hypoglycemic agents in adults with type 2 diabetes, have neuroprotective effects in preclinical models of central nervous system injury, and in children with neuropsychomotor impairments linked to neonatal diabetes secondary to ATP-sensitive potassium channel mutations. In the human and rodent retina, we show that the glibenclamide-activated channel sulfonylurea receptor 1 (SUR1) is expressed in the retina and enriched in the macula; we also show that it colocalizes with the potassium channel Kir6.2, and with the cation channel transporter TRPM4. Glibenclamide (glyburide), administered at doses that did not decrease the glycemia, or injected directly into the eye, protected the structure and the function of the retina in various models of retinal injury that recapitulate the pathogenic neurodegenerative events in the diabetic retina. The downregulation of SUR1 using a siRNA suppressed the neuroprotective effects of glibenclamide on excitotoxic stress-induced cell death. The glibenclamide effects include the transcriptional regulation of antioxidant and neuroprotective genes. Ocular glibenclamide could be repurposed for diabetic retinopathy.

An update on the pharmacological management and prevention of cerebral edema: current therapeutic strategies

Introduction: Cerebral edema is a common complication of multiple neurological diseases and is a strong predictor of outcome, especially in traumatic brain injury and large hemispheric infarction.Areas Covered: Traditional and current treatments of cerebral edema include treatment with osmotherapy or decompressive craniectomy at the time of clinical deterioration. The authors discuss preclinical and clinical models of a variety of neurological disease states that have identified receptors, ion transporters, and channels involved in the development of cerebral edema as well as modulation of these receptors with promising agents.Expert opinion: Further study is needed on the safety and efficacy of the agents discussed. IV glibenclamide has shown promise in preclinical and clinical trials of cerebral edema in large hemispheric infarct and traumatic brain injury. Consideration of underlying pathophysiology and pharmacodynamics is vital, as the synergistic use of agents has the potential to drastically mitigate cerebral edema and secondary brain injury thusly transforming our treatment paradigms.

Trends in Demographics and Markers of Injury Severity in Traumatic Cervical Spinal Cord Injury

Over the past four decades, there have been progressive changes in the epidemiology of traumatic spinal cord injury (tSCI). We assessed trends in demographic and injury-related variables in traumatic cervical spinal cord injury (tCSCI) patients over an 18-year period at a single Level I trauma center. We included all magnetic resonance imaging-confirmed tCSCI patients ≥15 years of age for years 2001-2018. Among 1420 patients, 78.3% were male with a mean age 51.5 years. Etiology included falls (46.9%), motor vehicle collisions (MVCs; 34.2%), and sports injuries (10.9%). Median American Spinal Injury Association (ASIA) Motor Score (AMS) was 44, complete tCSCI was noted in 29.6% of patients, fracture dislocations were noted in 44.7%, and median intramedullary lesion length (IMLL) was 30.8 mm (complete injuries 56.3 mm and incomplete injuries 27.4 mm). Over the study period, mean age and proportion of falls increased (p < 0.001) whereas proportion attributable to MVCs and sports injuries decreased (p < 0.001). Incomplete injuries, AMS, and the proportion of patients with no fracture dislocations increased whereas complete injuries decreased significantly. IMLL declined (p = 0.17) and proportion with hematomyelia did not change significantly. In adjusted regression models, increase in age and decreases in prevalence of MVC mechanism and complete injuries over time remained statistically significant. Changes in demographic and injury-related characteristics of tCSCI patients over time may help explain the observed improvement in outcomes. Further, improved clinical outcomes and drop in IMLL may reflect improvements in initial risk assessment and pre-hospital management, advances in healthcare delivery, and preventive measures including public education.

Hemorrhagic Transformation After Tissue Plasminogen Activator Treatment in Acute Ischemic Stroke

Hemorrhagic transformation (HT) is a common complication after thrombolysis with recombinant tissue-type plasminogen activator (rt-PA) in ischemic stroke. In this article, recent research progress of HT in vivo and in vitro studies was reviewed. We have discussed new potential mechanisms and possible experimental models of HT development, as well as possible biomarkers and treatment methods. Meanwhile, we compared and analyzed rodent models, large animal models and in vitro BBB models of HT, and the limitations of these models were discussed. The molecular mechanism of HT was investigated in terms of BBB disruption, rt-PA neurotoxicity and the effect of neuroinflammation, matrix metalloproteinases, reactive oxygen species. The clinical features to predict HT were represented including blood biomarkers and clinical factors. Recent progress in neuroprotective strategies to improve HT after stroke treated with rt-PA is outlined. Further efforts need to be made to reduce the risk of HT after rt-PA therapy and improve the clinical prognosis of patients with ischemic stroke.

Sodium Tanshinone IIA Silate Exerts Microcirculation Protective Effects against Spinal Cord Injury In Vitro and In Vivo

Spinal cord microcirculation involves functioning endothelial cells at the blood spinal cord barrier (BSCB) and maintains normal functioning of spinal cord neurons, axons, and glial cells. Protection of both the function and integrity of endothelial cells as well as the prevention of BSCB disruption may be a strong strategy for the treatment of spinal cord injury (SCI) cases. Sodium Tanshinone IIA silate (STS) is used for the treatment of coronary heart disease and improves microcirculation. Whether STS exhibits protective effects for SCI microcirculation is not yet clear. The purpose of this study is to investigate the protective effects of STS on oxygen-glucose deprivation- (OGD-) induced injury of spinal cord endothelial cells (SCMECs) in vitro and to explore effects on BSCB and neurovascular protection in vivo. SCMECs were treated with various concentrations of STS (1 μM, 3 μM, and 10 μM) for 24 h with or without OGD-induction. Cell viability, tube formation, migration, and expression of Notch signaling pathway components were evaluated. Histopathological evaluation (H&E), Nissl staining, BSCB permeability, and the expression levels of von Willebrand Factor (vWF), CD31, NeuN, and Notch signaling pathway components were analyzed. STS was found to improve SCMEC functions and reduce inflammatory mediators after OGD. STS also relieved histopathological damage, increased zonula occludens-1 (ZO-1), inhibited BSCB permeability, rescued microvessels, protected motor neuromas, and improved functional recovery in a SCI model. Moreover, we uncovered that the Notch signaling pathway plays an important role during these processes. These results indicated that STS protects microcirculation in SCI, which may be used as a therapeutic strategy for SCI in the future.

Mechanical stress regulates autophagic flux to affect apoptosis after spinal cord injury

Increased mechanical stress after spinal cord injury (SCI) expands the scope of nerve tissue damage and exacerbates nerve function defects. Surgical decompression after SCI is a conventional therapeutic strategy and has been proven to have neuroprotective effects. However, the mechanisms of the interaction between mechanical stress and neurons are currently unknown. In this study, we monitored intramedullary pressure (IMP) and investigated the therapeutic benefit of decompression (including durotomy and piotomy) after injury and its underlying mechanisms in SCI. We found that decreased IMP promotes the generation and degradation of LC3 II, promotes the degradation of p62 and enhances autophagic flux to alleviate apoptosis. The lysosomal dysfunction was reduced after decompression. Piotomy was better than durotomy for the histological repair of spinal cord tissue after SCI. However, the autophagy‐lysosomal pathway inhibitor chloroquine (CQ) partially reversed the apoptosis inhibition caused by piotomy after SCI, and the structural damage was also aggravated after CQ administration. An antibody microarray analysis showed that decompression may reverse the up‐regulated abundance of p‐PI3K, p‐AKT and p‐mTOR caused by SCI. Our findings may contribute to a better understanding of the mechanism of decompression and the effects of mechanical stress on autophagy after SCI.

Clinical Trial Design-A Review-With Emphasis on Acute Intervertebral Disc Herniation

There is a clear need for new methods of treatment of acute disc herniation in dogs, most obviously to address the permanent loss of function that can arise because of the associated spinal cord injury. Clinical trials form the optimal method to introduce new therapies into everyday clinical practice because they are a reliable source of unbiased evidence of effectiveness. Although many designs are available, parallel cohort trials are most widely applicable to acute disc herniation in dogs. In this review another key trial design decision—that between pragmatic and explanatory approaches—is highlighted and used as a theme to illustrate the close relationship between trial objective and design. Acute disc herniation, and acute spinal cord injury, is common in dogs and there is a multitude of candidate interventions that could be trialed. Most current obstacles to large-scale clinical trials in dogs can be overcome by collaboration and cooperation amongst interested veterinarians.

ABCC8 mRNA expression is an independent prognostic factor for glioma and can predict chemosensitivity

Glioma is the most common primary intracranial tumor and is associated with very low survival rates. The development of reliable biomarkers can help to elucidate the molecular mechanisms involved in glioma development. Here the expression of ABCC8 mRNA, clinical characteristics, and survival information based on 1893 glioma samples from four independent databases were analyzed. The expression patterns of ABCC8 mRNA were compared by a Chi square test. The overall survival rate of gliomas was evaluated according to the expression level of ABCC8 mRNA. The prognostic value of this marker in gliomas was tested using Cox single factor and multi factor regression analyses. We found patients with low WHO grade, oligodendrocytoma, low molecular grade, IDH mutation, and 1p19q combined deletion had high ABCC8 mRNA expression. The patients with high expression of ABCC8 mRNA had longer survival. ABCC8 mRNA expression was a new independent prognostic index for glioma. Temozolomide chemotherapy was an independent index to prolong overall survival in high ABCC8 mRNA expression glioma patients, whereas in patients with low expression, there was no significant difference. So ABCC8 mRNA expression could be an independent prognostic indicator for glioma patients and could predict the sensitivity of glioma to temozolomide.

Modeling blood-brain barrier pathology in cerebrovascular disease in vitro: current and future paradigms

The complexity of the blood-brain barrier (BBB) and neurovascular unit (NVU) was and still is a challenge to bridge. A highly selective, restrictive and dynamic barrier, formed at the interface of blood and brain, the BBB is a "gatekeeper" and guardian of brain homeostasis and it also acts as a "sensor" of pathological events in blood and brain. The majority of brain and cerebrovascular pathologies are associated with BBB dysfunction, where changes at the BBB can lead to or support disease development. Thus, an ultimate goal of BBB research is to develop competent and highly translational models to understand mechanisms of BBB/NVU pathology and enable discovery and development of therapeutic strategies to improve vascular health and for the efficient delivery of drugs. This review article focuses on the progress being made to model BBB injury in cerebrovascular diseases in vitro.

Efficacy of Ultra-Early (< 12 h), Early (12-24 h), and Late (>24-138.5 h) Surgery with Magnetic Resonance Imaging-Confirmed Decompression in American Spinal Injury Association Impairment Scale Grades A, B, and C Cervical Spinal Cord Injury

In cervical traumatic spinal cord injury (TSCI), the therapeutic effect of timing of surgery on neurological recovery remains uncertain. Additionally, the relationship between extent of decompression, imaging biomarker evidence of injury severity, and outcome is incompletely understood. We investigated the effect of timing of decompression on long-term neurological outcome in patients with complete spinal cord decompression confirmed on postoperative magnetic resonance imaging (MRI). American Spinal Injury Association (ASIA) Impairment Scale (AIS) grade conversion was determined in 72 AIS grades A, B, and C patients 6 months after confirmed decompression. Thirty-two patients underwent decompressive surgery ultra-early (< 12 h), 25 underwent decompressive surgery early (12-24 h), and 15 underwent decompressive surgery late (> 24-138.5 h) after injury. Age, gender, injury mechanism, intramedullary lesion length (IMLL) on MRI, admission ASIA motor score, and surgical technique were not statistically different among groups. Motor complete patients (p = 0.009) and those with fracture dislocations (p = 0.01) tended to be operated on earlier. Improvement of one grade or more was present in 55.6% of AIS grade A, 60.9% of AIS grade B, and 86.4% of AIS grade C patients. Admission AIS motor score (p = 0.0004) and pre-operative IMLL (p = 0.00001) were the strongest predictors of neurological outcome. AIS grade improvement occurred in 65.6%, 60%, and 80% of patients who underwent decompression ultra-early, early, and late, respectively (p = 0.424). Multiple regression analysis revealed that IMLL was the only significant variable predictive of AIS grade conversion to a better grade (odds ratio, 0.908; confidence interval [CI], 0.862-0.957; p < 0.001). We conclude that in patients with post-operative MRI confirmation of complete decompression following cervical TSCI, pre-operative IMLL, not the timing of surgery, determines long-term neurological outcome.

Role of Sulfonylurea Receptor 1 and Glibenclamide in Traumatic Brain Injury: A Review of the Evidence

Cerebral edema and contusion expansion are major determinants of morbidity and mortality after TBI. Current treatment options are reactive, suboptimal and associated with significant side effects. First discovered in models of focal cerebral ischemia, there is increasing evidence that the sulfonylurea receptor 1 (SUR1)-Transient receptor potential melastatin 4 (TRPM4) channel plays a key role in these critical secondary injury processes after TBI. Targeted SUR1-TRPM4 channel inhibition with glibenclamide has been shown to reduce edema and progression of hemorrhage, particularly in preclinical models of contusional TBI. Results from small clinical trials evaluating glibenclamide in TBI have been encouraging. A Phase-2 study evaluating the safety and efficacy of intravenous glibenclamide (BIIB093) in brain contusion is actively enrolling subjects. In this comprehensive narrative review, we summarize the molecular basis of SUR1-TRPM4 related pathology and discuss TBI-specific expression patterns, biomarker potential, genetic variation, preclinical experiments, and clinical studies evaluating the utility of treatment with glibenclamide in this disease.

BIIB093 (IV glibenclamide): an investigational compound for the prevention and treatment of severe cerebral edema

Introduction: Brain swelling due to edema formation is a major cause of neurological deterioration and death in patients with large hemispheric infarction (LHI) and severe traumatic brain injury (TBI), especially contusion-TBI. Preclinical studies have shown that SUR1-TRPM4 channels play a critical role in edema formation and brain swelling in LHI and TBI. Glibenclamide, a sulfonylurea drug and potent inhibitor of SUR1-TRPM4, was reformulated for intravenous injection, known as BIIB093.Areas covered: We discuss the findings from Phase 2 clinical trials of BIIB093 in patients with LHI (GAMES-Pilot and GAMES-RP) and from a small Phase 2 clinical trial in patients with TBI. For the GAMES trials, we review data on objective biological variables, adjudicated edema-related endpoints, functional outcomes, and mortality which, despite missing the primary endpoint, supported the initiation of a Phase 3 trial in LHI (CHARM). For the TBI trial, we review data on MRI measures of edema and the initiation of a Phase 2 trial in contusion-TBI (ASTRAL).Expert opinion: Emerging clinical data show that BIIB093 has the potential to transform our management of patients with LHI, contusion-TBI and other conditions in which swelling leads to neurological deterioration and death.

A brief period of moderate noxious stimulation induces hemorrhage and impairs locomotor recovery after spinal cord injury

Spinal cord injury (SCI) is often accompanied by additional tissue damage (polytrauma) that provides a source of pain input. Our studies suggest that this pain input may be detrimental to long-term recovery. In a rodent model, we have shown that engaging pain (nociceptive) fibers caudal to a lower thoracic contusion SCI impairs recovery of locomotor function and increases tissue loss (secondary injury) and hemorrhage at the site of injury. In these studies, nociceptive fibers were activated using intermittent electrical stimulation. The stimulation parameters were derived from earlier studies demonstrating that 6 min of noxious stimulation, at an intensity (1.5 mA) that engages unmyelinated C (pain) fibers, induces a form of maladaptive plasticity within the lumbosacral spinal cord. We hypothesized that both shorter bouts of nociceptive input and lower intensities of stimulation will decrease locomotor function and increase spinal cord hemorrhage when rats have a spinal cord contusion. To test this, the present study exposed rats to electrical stimulation 24 h after a moderate lower thoracic contusion SCI. One group of rats received 1.5 mA stimulation for 0, 14.4, 72, or 180 s. Another group received six minutes of stimulation at 0, 0.17, 0.5, and 1.5 mA. Just 72 s of stimulation induced an acute disruption in motor performance, increased hemorrhage, and undermined the recovery of locomotor function. Likewise, less intense (0.5 mA) stimulation produced an acute disruption in motor performance, fueled hemorrhage, and impaired long-term recovery. The results imply that a brief period of moderate pain input can trigger hemorrhage after SCI and undermine long-term recovery. This highlights the importance of managing nociceptive signals after concurrent peripheral and central nervous system injuries.

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

INTRODUCTION

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

METHODS AND ANALYSIS

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

ETHICS AND DISSEMINATION

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

TRIAL REGISTRATION NUMBERS

NCT02524379 and 2014H0335.

Moving beyond the glial scar for spinal cord repair

Traumatic spinal cord injury results in severe and irreversible loss of function. The injury triggers a complex cascade of inflammatory and pathological processes, culminating in formation of a scar. While traditionally referred to as a glial scar, the spinal injury scar in fact comprises multiple cellular and extracellular components. This multidimensional nature should be considered when aiming to understand the role of scarring in limiting tissue repair and recovery. In this Review we discuss recent advances in understanding the composition and phenotypic characteristics of the spinal injury scar, the oversimplification of defining the scar in binary terms as good or bad, and the development of therapeutic approaches to target scar components to enable improved functional outcome after spinal cord injury.

Magnetic Resonance Imaging Pilot Study of Intravenous Glyburide in Traumatic Brain Injury

Pre-clinical studies of traumatic brain injury (TBI) show that glyburide reduces edema and hemorrhagic progression of contusions. We conducted a small Phase II, three-institution, randomized placebo-controlled trial of subjects with TBI to assess the safety and efficacy of intravenous (IV) glyburide. Twenty-eight subjects were randomized and underwent a 72-h infusion of IV glyburide or placebo, beginning within 10 h of trauma. Of the 28 subjects, 25 had Glasgow Coma Scale (GCS) scores of 6-10, and 14 had contusions. There were no differences in adverse events (AEs) or severe adverse events (ASEs) between groups. The magnetic resonance imaging (MRI) percent change at 72-168 h from screening/baseline was compared between the glyburide and placebo groups. Analysis of contusions (7 per group) showed that lesion volumes (hemorrhage plus edema) increased 1036% with placebo versus 136% with glyburide (p = 0.15), and that hemorrhage volumes increased 11.6% with placebo but decreased 29.6% with glyburide (p = 0.62). Three diffusion MRI measures of edema were quantified: mean diffusivity (MD), free water (FW), and tissue MD (MDt), corresponding to overall, extracellular, and intracellular water, respectively. The percent change with time for each measure was compared in lesions (n = 14) versus uninjured white matter (n = 24) in subjects receiving placebo (n = 20) or glyburide (n = 18). For placebo, the percent change in lesions for all three measures was significantly different compared with uninjured white matter (analysis of variance [ANOVA], p < 0.02), consistent with worsening of edema in untreated contusions. In contrast, for glyburide, the percent change in lesions for all three measures was not significantly different compared with uninjured white matter. Further study of IV glyburide in contusion TBI is warranted.

Myelin status and oligodendrocyte lineage cells over time after spinal cord injury: What do we know and what still needs to be unwrapped?

Spinal cord injury (SCI) affects over 17,000 individuals in the United States per year, resulting in sudden motor, sensory and autonomic impairments below the level of injury. These deficits may be due at least in part to the loss of oligodendrocytes and demyelination of spared axons as it leads to slowed or blocked conduction through the lesion site. It has long been accepted that progenitor cells form new oligodendrocytes after SCI, resulting in the acute formation of new myelin on demyelinated axons. However, the chronicity of demyelination and the functional significance of remyelination remain contentious. Here we review work examining demyelination and remyelination after SCI as well as the current understanding of oligodendrocyte lineage cell responses to spinal trauma, including the surprisingly long-lasting response of NG2+ oligodendrocyte progenitor cells (OPCs) to proliferate and differentiate into new myelinating oligodendrocytes for months after SCI. OPCs are highly sensitive to microenvironmental changes, and therefore respond to the ever-changing post-SCI milieu, including influx of blood, monocytes and neutrophils; activation of microglia and macrophages; changes in cytokines, chemokines and growth factors such as ciliary neurotrophic factor and fibroblast growth factor-2; glutamate excitotoxicity; and axon degeneration and sprouting. We discuss how these changes relate to spontaneous oligodendrogenesis and remyelination, the evidence for and against demyelination being an important clinical problem and if remyelination contributes to motor recovery.

The adeno-associated virus rh10 vector is an effective gene transfer system for chronic spinal cord injury

Treatment options for chronic spinal cord injury (SCI) remain limited due to unfavourable changes in the microenvironment. Gene therapy can overcome these barriers through continuous delivery of therapeutic gene products to the target tissue. In particular, adeno-associated virus (AAV) vectors are potential candidates for use in chronic SCI, considering their safety and stable gene expression in vivo. Given that different AAV serotypes display different cellular tropisms, it is extremely important to select an optimal serotype for establishing a gene transfer system during the chronic phase of SCI. Therefore, we generated multiple AAV serotypes expressing ffLuc-cp156, a fusion protein of firefly luciferase and Venus, a variant of yellow fluorescent protein with fast and efficient maturation, as a reporter, and we performed intraparenchymal injection in a chronic SCI mouse model. Among the various serotypes tested, AAVrh10 displayed the highest photon count on bioluminescence imaging. Immunohistological analysis revealed that AAVrh10 showed favourable tropism for neurons, astrocytes, and oligodendrocytes. Additionally, with AAVrh10, the area expressing Venus was larger in the injury epicentre and extended to the surrounding tissue. Furthermore, the fluorescence intensity was significantly higher with AAVrh10 than with the other vectors. These results indicate that AAVrh10 may be an appropriate serotype for gene delivery to the chronically injured spinal cord. This promising tool may be applied for research and development related to the treatment of chronic SCI.

Extent of Spinal Cord Decompression in Motor Complete (American Spinal Injury Association Impairment Scale Grades A and B) Traumatic Spinal Cord Injury Patients: Post-Operative Magnetic Resonance Imaging Analysis of Standard Operative Approaches

Although decompressive surgery following traumatic spinal cord injury (TSCI) is recommended, adequate surgical decompression is rarely verified via imaging. We utilized magnetic resonance imaging (MRI) to analyze the rate of spinal cord decompression after surgery. Pre-operative (within 8 h of injury) and post-operative (within 48 h of injury) MRI images of 184 motor complete patients (American Spinal Injury Association Impairment Scale [AIS] grade A = 119, AIS grade B = 65) were reviewed to verify spinal cord decompression. Decompression was defined as the presence of a patent subarachnoid space around a swollen spinal cord. Of the 184 patients, 100 (54.3%) underwent anterior cervical discectomy and fusion (ACDF), and 53 of them also underwent laminectomy. Of the 184 patients, 55 (29.9%) underwent anterior cervical corpectomy and fusion (ACCF), with (26 patients) or without (29 patients) laminectomy. Twenty-nine patients (16%) underwent stand-alone laminectomy. Decompression was verified in 121 patients (66%). The rates of decompression in patients who underwent ACDF and ACCF without laminectomy were 46.8% and 58.6%, respectively. Among these patients, performing a laminectomy increased the rate of decompression (72% and 73.1% of patients, respectively). Twenty-five of 29 (86.2%) patients who underwent a stand-alone laminectomy were found to be successfully decompressed. The rates of decompression among patients who underwent laminectomy at one, two, three, four, or five levels were 58.3%, 68%, 78%, 80%, and 100%, respectively (p < 0.001). In multi-variate logistic regression analysis, only laminectomy was significantly associated with successful decompression (odds ratio 4.85; 95% confidence interval 2.2-10.6; p < 0.001). In motor complete TSCI patients, performing a laminectomy significantly increased the rate of successful spinal cord decompression, independent of whether anterior surgery was performed.