Pharmacological approaches to repair the injured spinal cord

Frontiers of spinal cord and spine repair: experimental approaches for repair of spinal cord injury

Regeneration of injured CNS neurons was once thought to be an unachievable goal. Most patients with significant damage to the spinal cord suffer from permanently impaired neurological function. A century of research, however, has led to an understanding of multiple factors that limit CNS regeneration and from this knowledge experimental strategies have emerged for enhancing CNS repair. Some of these approaches have undergone human translation. Nevertheless, translating experimental findings to human trials has been more challenging than anticipated. In this chapter, we will review the current state of knowledge regarding central axonal growth failure after injury, and approaches taken to enhance recovery after SCI.

The ameliorating effect of dantrolene on the morphology of urinary bladder in spinal cord injured rats

In animal models of spinal cord injury (SCI), the urinary bladder can undergo significant structural and physiological alterations. Dantrolene has been shown to be neuroprotective by reducing neuronal apoptosis after SCI. Furthermore, in addition to its anti-inflammatory and antioxidant properties, it appears to have a beneficial action on voiding, once this drug acts on the external urethral sphincter relaxation. In the present study, we investigated the effects of dantrolene on urinary bladder injury that follows experimental SCI. Forty-six male Wistar rats were laminectomized at T13, and a compressive trauma was performed to induce SCI. After euthanasia, the urinary bladder was removed for gross and histological evaluation. Traumatized animals showed urinary retention with severe hemorrhagic cystitis. Injured animals treated with dantrolene had less bladder hemorrhage and inflammatory infiltrate than those treated with placebo (p<0.05). Our results demonstrate that dantrolene may protect against urinary bladder lesions that follow SCI. Treating spinal cord-injured patients with this agent may be a promising additional therapeutic strategy to alleviate the accompanying inflammatory process. The results of the current study show that dantrolene has protective effects on spinal cord contusion-induced urinary bladder injury. The impaired integrity of bladder morphology was ameliorated by dantrolene treatment.

Rosuvastatin, a new generation 3-hydroxy-3-methylglutaryl coenzyme a reductase inhibitor, reduces ischemia/reperfusion-induced spinal cord tissue injury in rats

BACKGROUND

Severe neurological injury still represents one of the most devastating complications occurring after surgical repair of thoracoabdominal aneurysms. We aimed to investigate the role of rosuvastatin (RSV) against ischemia/reperfusion injury in an experimental model of spinal cord ischemia in rats.

METHODS

Experimental groups included control group (n = 8), ischemia/reperfusion group (n = 8) undergoing aortic occlusion without pharmacologic treatment, and RSV-treated group (n = 8) receiving 10 mg/kg/day of RSV orally for 3 days before spinal cord ischemia. Spinal cord ischemia was induced by occlusion of the abdominal aorta between the left renal artery and aortic bifurcation for 45 minutes, followed by reperfusion. Neurological status was assessed before spinal ischemia and at 48 hours postoperatively. Spinal cords were harvested for histopathologic examination with hematoxylin-eosin staining and biochemical analysis for tissue malondialdehyde, superoxide dismutase, and glutathione peroxidase levels.

RESULTS

Decreased spinal cord tissue malondialdehyde levels (p = .01) and increased tissue superoxide dismutase (p = .01) and glutathione peroxidase (p = .09) levels were observed in the RSV-treated group, as compared with the ischemia group. Histopathologic analyses demonstrated typical changes of ischemic necrosis in the ischemia group; however, RSV attenuated tissue necrosis. Total injury score in the RSV-treated group was significantly decreased, as compared with the ischemia group (p < .05). The Tarlov scores at 48 hours postoperatively were higher in the RSV group as compared with the ischemia group.

CONCLUSION

RSV administration before spinal cord ischemia reduces spinal cord tissue injury by increasing antioxidant enzyme levels and may reduce the incidence of associated neurological dysfunction.

Neuroprotective effects of gabapentin on spinal cord ischemia-reperfusion injury in rabbits

Object

Extensive research has been focused on neuroprotection after spinal cord trauma to alleviate the effects of secondary injury. This study aims to investigate the neuroprotective effects of gabapentin in an experimental spinal cord ischemia reperfusion injury.

Methods

Thirty-two adult male New Zealand white rabbits received spinal cord ischemic injury using the aortic occlusion model. Animals were divided into 4 groups (sham, control, low-dose, and high-dose treatment groups; 8 rabbits in each group). High (200 mg/kg) and low (30 mg/kg) doses of gabapentin were administered to the animals in the treatment groups after spinal cord ischemic injury. Neurological status of the animals, ultrastructural findings in injured tissue samples, and levels of tissue injury markers in these 2 groups were compared with findings in the animals that did not receive the ischemic procedure (sham-operated group) and those that received normal saline after administration of ischemia.

Results

Regarding levels of tissue injury marker levels after ischemic injury, animals in the gabapentin-treated groups demonstrated better results than animals in the other groups. The ultrastructural findings and caspase-3 activity were similar. The treatment groups demonstrated better results than the other groups.

Conclusions

Gabapentin demonstrated significant neuroprotection after early phases of ischemic injury. Further studies with different experimental settings including neurological outcome are required to achieve conclusive results.

Reduction in expression of the astrocyte glutamate transporter, GLT1, worsens functional and histological outcomes following traumatic spinal cord injury

The astrocyte glutamate transporter, GLT1, is responsible for the vast majority of glutamate uptake in the adult central nervous system (CNS), thereby regulating extracellular glutamate homeostasis and preventing excitotoxicity. Glutamate dysregulation plays a central role in outcome following traumatic spinal cord injury (SCI). To determine the role of GLT1 in secondary cell loss following SCI, mice heterozygous for the GLT1 astrocyte glutamate transporter (GLT1+/-) and wild-type mice received thoracic crush SCI. Compared with wild-type controls, GLT1+/- mice had an attenuated recovery in hindlimb motor function, increased lesion size, and decreased tissue sparing. GLT1+/- mice showed a decrease in intraspinal GLT1 protein and functional glutamate uptake compared with wild-type mice, accompanied by increased apoptosis and neuronal loss following crush injury. These results suggest that astrocyte GLT1 plays a role in limiting secondary cell death following SCI, and also show that compromise of key astrocyte functions has significant effects on outcome following traumatic CNS injury. These findings also suggest that increasing intraspinal GLT1 expression may represent a therapeutically relevant target for SCI treatment.

RAR/RXR and PPAR/RXR Signaling in Spinal Cord Injury

The retinoid acid receptors (RAR) and peroxisome proliferator-activated receptors (PPAR) have been implicated in the regulation of inflammatory reactions. Both receptor families contain ligand-activated transcription factors which form heterodimers with retinoid X receptors (RXR). We review data that imply RAR/RXR and PPAR/RXR pathways in physiological reactions after spinal cord injury. Experiments show how RAR signaling may improve axonal regeneration and modulate reactions of glia cells. While anti-inflammatory properties of PPAR are well documented in the periphery, their possible roles in the central nervous system have only recently become evident. Due to its anti-inflammatory function this transcription factor family promises to be a useful target after spinal cord or brain lesions.

Association of VSNL1 with schizophrenia, frontal cortical function, and biological significance for its gene product as a modulator of cAMP levels and neuronal morphology

We report an association of single-nucleotide polymorphisms (SNPs) for the VSNL1 gene (visinin-like 1) with schizophrenia and frontal cortical function in a sample of patients with Diagnostic and Statistical Manual of Mental Disorder-IV (DSM-IV) diagnoses of schizophrenia, compared with healthy controls. Moreover, VSNL1 SNPs were associated with performance in the Wisconsin Card Sorting Test, a measure for the assessment of frontal cortical function. The VSNL1 gene product, Visinin-like-protein-1 (VILIP-1), is a member of the neuronal EF-hand Ca(2+)-sensor protein family. Previously, VILIP-1 mRNA and protein expression were shown to be altered in animal models and in schizophrenia patients. VILIP-1 influences cytosolic cyclic adenosine mono phosphate (cAMP) levels, cell migration, exocytotic processes and differentiation in the periphery. This raises the question, whether, similar to other potential schizophrenia susceptibility genes such as Disc1, PDE4B and Akt, VSNL1 may affect cAMP signaling and neurite outgrowth in neurons. In dissociated rat hippocampal neurons, VILIP-1 small interfering RNA knockdown decreased cAMP levels and reduced dendrite branching, compared with control-transfected cells. In contrast, VILIP-1 overexpression had the opposite effect. Similar results have been obtained in the human dopaminergic neuronal cell line SH-SY5Y, where the effect on neurite branching and length was attenuated by the adenylyl cyclase inhibitor 2',5'-dideoxyadenosine and the protein kinase A inhibitor KT5720. These results show that the association of VSNL1 SNPs with the disease and cognitive impairments, together with previously observed pathological changes in VILIP-1 protein expression, possibly occurring during brain development, may contribute to the morphological and functional deficits observed in schizophrenia.

Molecular Mechanisms Underlying Cell Death in Spinal Networks in Relation to Locomotor Activity After Acute Injury in vitro

Understanding the pathophysiological changes triggered by an acute spinal cord injury is a primary goal to prevent and treat chronic disability with a mechanism-based approach. After the primary phase of rapid cell death at the injury site, secondary damage occurs via autodestruction of unscathed tissue through complex cell-death mechanisms that comprise caspase-dependent and caspase-independent pathways. To devise novel neuroprotective strategies to restore locomotion, it is, therefore, necessary to focus on the death mechanisms of neurons and glia within spinal locomotor networks. To this end, the availability of in vitro preparations of the rodent spinal cord capable of expressing locomotor-like oscillatory patterns recorded electrophysiologically from motoneuron pools offers the novel opportunity to correlate locomotor network function with molecular and histological changes long after an acute experimental lesion. Distinct forms of damage to the in vitro spinal cord, namely excitotoxic stimulation or severe metabolic perturbation (with oxidative stress, hypoxia/aglycemia), can be applied with differential outcome in terms of cell types and functional loss. In either case, cell death is a delayed phenomenon developing over several hours. Neurons are more vulnerable to excitotoxicity and more resistant to metabolic perturbation, while the opposite holds true for glia. Neurons mainly die because of hyperactivation of poly(ADP-ribose) polymerase-1 (PARP-1) with subsequent DNA damage and mitochondrial energy collapse. Conversely, glial cells die predominantly by apoptosis. It is likely that early neuroprotection against acute spinal injury may require tailor-made drugs targeted to specific cell-death processes of certain cell types within the locomotor circuitry. Furthermore, comparison of network size and function before and after graded injury provides an estimate of the minimal network membership to express the locomotor program.

Studies of locomotor network neuroprotection by the selective poly(ADP-ribose) polymerase-1 inhibitor PJ-34 against excitotoxic injury to the rat spinal cord in vitro

Delayed neuronal destruction after acute spinal injury is attributed to excitotoxicity mediated by hyperactivation of poly(ADP-ribose) polymerase-1 (PARP-1) that induces 'parthanatos', namely a non-apoptotic cell death mechanism. With an in vitro model of excitotoxicity, we have previously observed parthanatos of rat spinal cord locomotor networks to be decreased by a broad spectrum PARP-1 inhibitor. The present study investigated whether the selective PARP-1 inhibitor N-(6-oxo-5,6-dihydrophenanthridin-2-yl)-(N,N-dimethylamino)acetamide.HCl (PJ-34) not only protected networks from kainate-evoked excitotoxicity, but also prevented loss of locomotor patterns recorded as fictive locomotion from lumbar (L) ventral roots (VRs) 24 h later. PJ-34 (60 μm) blocked PARP-1 activation and preserved dorsal, central and ventral gray matter with maintained reflex activity even after a large dose of kainate. Fictive locomotion could not, however, be restored by either electrical stimulation or bath-applied neurochemicals (N-methyl-D-aspartate plus 5-hydroxytryptamine). A low kainate concentration induced less histological damage that was widely prevented by PJ-34. Nonetheless, fictive locomotion was observed in just over 50% of preparations whose histological profile did not differ (except for the dorsal horn) from those lacking such a rhythm. Our data show that inhibition of PARP-1 could amply preserve spinal network histology after excitotoxicity, with return of locomotor patterns only when the excitotoxic stimulus was moderate. These results demonstrated divergence between histological and functional outcome, implying a narrow borderline between loss of fictive locomotion and neuronal preservation. Our data suggest that either damage of a few unidentified neurons or functional network inhibition was critical for ensuring locomotor cycles.

Pharmacological interventions for spinal cord injury: where do we stand? How might we step forward?

Despite numerous studies reporting some measures of efficacy in the animal literature, there are currently no effective therapies for the treatment of traumatic spinal cord injuries (SCI) in humans. The purpose of this review is to delineate key pathophysiological processes that contribute to neurological deficits after SCI, as well as to describe examples of pharmacological approaches that are currently being tested in clinical trials, or nearing clinical translation, for the therapeutic management of SCI. In particular, we will describe the mechanistic rationale to promote neuroprotection and/or functional recovery based on theoretical, yet targeted pathological events. Finally, we will consider the clinical relevancy for emerging evidence that pharmacologically targeting mitochondrial dysfunction following injury may hold the greatest potential for increasing tissue sparing and, consequently, the extent of functional recovery following traumatic SCI.

Immunohistochemical analysis of TIMP-2 and collagen types I and IV in experimental spinal cord ischemia-reperfusion injury in rats

BACKGROUND

Thoracic and thoracoabdominal aortic intervention carries a significant risk of spinal cord ischemia. The pathophysiologic mechanisms that cause hypoxic/ischemic injury to the spinal cord have not been totally explained. In normal spinal cord, neurons and glial cells do not express type IV collagen. Type IV collagen produced by reactive astrocytes is reported to participate in glial scar formation. Tissue inhibitors of metalloproteinases (TIMPs) are endogenous inhibitors that regulate the activity of the matrix metalloproteinases (MMPs). TIMP-2 binds strongly with MMP-2, facilitating activation by membrane-type MMP. Imbalance between TIMPs and MMPs can lead to excessive degradation of matrix components. Type IV collagen involved in the blood-brain barrier disruption and glial scar formation, TIMP-2 influences MMP-2 that controls degradation of collagen I and IV.

OBJECTIVE

To examine the immunohistochemical analysis of TIMP-2 and collagen types I-IV in experimental spinal cord ischemia-reperfusion in rats.

METHODS

Thirty-two male Wistar rats weighing 250-300 g were divided into four groups: group S: sham group (n = 8); group 0P: 30-minute occlusion without perfusion (n = 8); group 3P: 30-minute occlusion and 3-hour perfusion (n = 8); and group 24P: 30-minute occlusion and 24-hour perfusion (n = 8). Infrarenal aorta was cross-clamped at two sites by using two aneurysm clips for 30 minutes. Reperfusion was provided after removal of the clips. Lumbar spinal cord segments were removed for immunohistochemical analysis.

RESULTS

TIMP-2 and collagen staining in 3-hour perfused (3P) group were nearly the same with sham group (S). TIMP-2 and collagen staining increased in the 24-hour perfused group.

CONCLUSION

Alterations in collagen levels may relate to the biphasic breakdown of the blood-brain barrier and collagen staining in new cell types with relation to glial scar formation. Our results demonstrate that 3-hour perfusion after occlusion in hypoxic/ischemic spinal cord injury seems to be the critical reversible period.

Selective adenosine A2A receptor agonists and antagonists protect against spinal cord injury through peripheral and central effects

BACKGROUND

Permanent functional deficits following spinal cord injury (SCI) arise both from mechanical injury and from secondary tissue reactions involving inflammation. Enhanced release of adenosine and glutamate soon after SCI represents a component in the sequelae that may be responsible for resulting functional deficits. The role of adenosine A2A receptor in central ischemia/trauma is still to be elucidated. In our previous studies we have demonstrated that the adenosine A2A receptor-selective agonist CGS21680, systemically administered after SCI, protects from tissue damage, locomotor dysfunction and different inflammatory readouts. In this work we studied the effect of the adenosine A2A receptor antagonist SCH58261, systemically administered after SCI, on the same parameters. We investigated the hypothesis that the main action mechanism of agonists and antagonists is at peripheral or central sites.

METHODS

Spinal trauma was induced by extradural compression of SC exposed via a four-level T5-T8 laminectomy in mouse. Three drug-dosing protocols were utilized: a short-term systemic administration by intraperitoneal injection, a chronic administration via osmotic minipump, and direct injection into the spinal cord.

RESULTS

SCH58261, systemically administered (0.01 mg/kg intraperitoneal. 1, 6 and 10 hours after SCI), reduced demyelination and levels of TNF-α, Fas-L, PAR, Bax expression and activation of JNK mitogen-activated protein kinase (MAPK) 24 hours after SCI. Chronic SCH58261 administration, by mini-osmotic pump delivery for 10 days, improved the neurological deficit up to 10 days after SCI. Adenosine A2A receptors are physiologically expressed in the spinal cord by astrocytes, microglia and oligodendrocytes. Soon after SCI (24 hours), these receptors showed enhanced expression in neurons. Both the A2A agonist and antagonist, administered intraperitoneally, reduced expression of the A2A receptor, ruling out the possibility that the neuroprotective effects of the A2A agonist are due to A2A receptor desensitization. When the A2A antagonist and agonist were centrally injected into injured SC, only SCH58261 appeared neuroprotective, while CGS21680 was ineffective.

CONCLUSIONS

Our results indicate that the A2A antagonist protects against SCI by acting on centrally located A2A receptors. It is likely that blockade of A2A receptors reduces excitotoxicity. In contrast, neuroprotection afforded by the A2A agonist may be primarily due to peripheral effects.

Spatial and temporal changes in promoter activity of the astrocyte glutamate transporter GLT1 following traumatic spinal cord injury

After traumatic spinal cord injury (SCI), there is an opportunity for preserving function by attenuating secondary cell loss. Astrocytes play crucial roles in the adult CNS and are responsible for the vast majority of glutamate buffering, potentially preventing excitotoxic loss of neurons and oligodendrocytes. We examined spatial and temporal changes in gene expression of the major astrocyte glutamate transporter GLT1 following moderate thoracic contusion SCI using transgenic BAC-GLT1-eGFP promoter reporter mice. In dorsal column white matter, total intensity of GLT1-eGFP expression per region was significantly reduced following SCI at both lesion epicenter and at rostral and caudal areas where no tissue loss occurred. This regional decrease in GLT1 expression was due to significant loss of GLT1-eGFP(+) cells, partially accounted for by apoptosis of eGFP(+) /GFAP(+) astrocytes in both white and gray matter. There were also decreased numbers of GLT1-eGFP-expressing cells in multiple gray matter regions following injury; nevertheless, there was sustained or even increased regional GLT1-eGFP expression in gray matter as a result of up-regulation in astrocytes that continued to express GLT1-eGFP. Although there were increased numbers of GFAP(+) cells both at the lesion site and in surrounding intact spinal cord following SCI, the majority of proliferating Ki67(+) /GFAP(+) astrocytes did not express GLT1-eGFP. These findings demonstrate that spatial and temporal alterations in GLT1 expression observed after SCI result from both astrocyte death and gene expression changes in surviving astrocytes. Results also suggest that following SCI a significant portion of astrocytes lacks GLT1 expression, possibly compromising the important role of astrocytes in glutamate homeostasis.

The effect of minocycline on motor neuron recovery and neuropathic pain in a rat model of spinal cord injury

OBJECTIVE

Minocycline, a second-generation tetracycline-class antibiotic, has been well established to exert a neuroprotective effect in animal models and neurodegenerative disease through the inhibition of microglia. Here, we investigated the effects of minocycline on motor recovery and neuropathic pain in a rat model of spinal cord injury.

METHODS

To simulate spinal cord injury, the rats' spinal cords were hemisected at the 10th thoracic level (T10). Minocycline was injected intraperitoneally, and was administered 30 minutes prior surgery and every second postoperative day until sacrifice 28 days after surgery. Motor recovery was assessed via the Basso-Beattie-Bresnahan test. Mechanical hyperalgesia was measured throughout the 28-day post-operative course via the von Frey test. Microglial and astrocyte activation was assessed by immunohistochemical staining for ionized calcium binding adaptor molecule 1 (Iba1) and glial fibrillary acidic protein (GFAP) at two sites: at the level of hemisection and at the 5th lumbar level (L5).

RESULTS

In rats, spinal cord hemisection reduced locomotor function and induced a mechanical hyperalgesia of the ipsilateral hind limb. The expression of Iba1 and GFAP was also increased in the dorsal and ventral horns of the spinal cord at the site of hemisection and at the L5 level. Intraperitoneal injection of minocycline facilitated overall motor recovery and attenuated mechanical hyperalgesia. The expression of Iba1 and GFAP in the spinal cord was also reduced in rats treated with minocycline.

CONCLUSION

By inhibiting microglia and astrocyte activation, minocycline may facilitate motor recovery and attenuate mechanical hyperalgesia in individuals with spinal cord injuries.

RhoA inactivation prevents photoreceptor axon retraction in an in vitro model of acute retinal detachment

PURPOSE

An early injury response to retinal detachment is disruption of synaptic connectivity between photoreceptors and second-order neurons. Most dramatic is the retraction of rod cell axons and their terminals away from the outer synaptic layer and toward their cell bodies. This study tested whether axonal retraction in detached retina was due to the activation of the small GTPase RhoA and was preventable using RhoA antagonists.

METHODS

Retinal detachments were created in in vitro preparations of porcine eyecups. RhoA activation was determined with a Rhotekin binding assay. To block axon retraction, drugs were applied to neural retinal explants either before or after detachment from the retinal pigment epithelium. Presynaptic movement was quantified by image analysis of double-labeled retinas examined with confocal microscopy.

RESULTS

Active RhoA increases transiently after detachment followed by morphologic evidence of axonal retraction over the next 24 hours. Pretreating the retina with a RhoA antagonist, CT-04, or a Rho kinase inhibitor, Y27632, at multiple concentrations significantly inhibited axonal retraction. Reducing calcium influx through L-type calcium channels with nicardipine also blocked retraction. To create a more plausible therapeutic scenario, drug treatments were delayed and applied after retinal detachment. The Rho kinase inhibitor, but not nicardipine, significantly blocked rod axonal retraction when applied up to 6 hours after detachment.

CONCLUSIONS

Thus, RhoA and downstream Rho kinase activity constitute part of the mechanism that produces rod axonal retraction in retinal explants. Treatments that manipulate RhoA signaling may promote synaptic stability after retinal detachment.

Development of complete thoracic spinal cord transection model in rats for delayed transplantation of stem cells

STUDY DESIGN

In vivo study of a rat spinal cord injury model.

OBJECTIVES

To develop complete transection model of thoracic spinal cord using a polymer sheet and a microtube relevant for delayed transplantation of stem cells.

SUMMARY OF BACKGROUND DATA

Stem cell transplantation for the regeneration of spinal cord injuries has used animal models. However, current models suffer from inflammation and leakage, which lessens their usefulness in studying delayed stem cell transplantation.

METHODS

Thoracic spinal cord at T9 level of adult Sprague-Dawley rats was exposed and a 50:50 sheet of poly(D,L-lactic-coglycolic acid) was inserted, exposed spinal cord was completely transected, and collagen was filled between the gap between the proximal and distal stumps of transected spinal cord. A microtube was placed and fixed between the polymer surfaces facing each other. Behavior testing, magnetic resonance imaging, and myelography were performed to characterize the new complete transection with a gap formation and polymer insertion (GAP) model and to compare the GAP model with the control models. Human mesenchymal stem cells (hMSCs) were transplanted into 3 models and immunohistochemistry and western blot were performed.

RESULTS

The inserted poly(D,L-lactic-coglycolic acid) sheet was completely disappeared 10 weeks after operation, but the inserted microtube remained firmly fixed in its original position. Myelography of the GAP model showed no leakage of contrast medium around the injured spinal cord, whereas magnetic resonance imaging of the severe contusion and simple transection models showed some leakage of contrast medium. Immunohistochemistry and western blot after hMSCs transplantation indicated that transplanted hMSCs survived and migrated well in the GAP model, and the deposition of inflammatory cells in GAP model was less than a simple transection model or severe contusion model.

CONCLUSION

The developed GAP model is more relevant for delayed transplantation of stem cells for the study of regeneration of spinal cord injury of rats.

Glutamate and ATP signalling in white matter pathology

Excessive signalling by excitatory neurotransmitters like glutamate and ATP can be deleterious to neurons and oligodendroglia, and cause disease. In particular, sustained activation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), kainate and N-methyl-d-aspartate (NMDA) receptors damages oligodendrocytes, a feature that depends entirely on Ca(2+) overload of the cytoplasm and that can be initiated by disruption of glutamate homeostasis. Thus, inhibition of glutamate uptake by activated microglia can compromise glutamate homeostasis and induce oligodendrocyte excitotoxicity. Moreover, non-lethal, brief activation of kainate receptors in oligodendrocytes rapidly sensitizes these cells to complement attack as a consequence of oxidative stress. In addition to glutamate, ATP signalling can directly trigger oligodendrocyte excitotoxicity via activation of Ca(2+) -permeable P2X7 purinergic receptors, which mediates ischaemic damage to white matter (WM) and causes lesions that are reminiscent of multiple sclerosis (MS) plaques. Conversely, blockade of P2X7 receptors attenuates post-ischaemic injury to WM and ameliorates chronic experimental autoimmune encephalomyelitis, a model of MS. Importantly, P2X7 expression is elevated in normal-appearing WM in patients with MS, suggesting that signalling through this receptor in oligodendrocytes may be enhanced in this disease. Altogether, these observations reveal novel mechanisms by which altered glutamate and ATP homeostasis can trigger oligodendrocyte death. This review aims at summarizing current knowledge about the mechanisms leading to WM damage as a consequence of altered neurotransmitter signalling, and their relevance to disease. This knowledge will generate new therapeutic avenues to treat more efficiently acute and chronic WM pathology.

A murine model of hypertonic saline as a treatment for acute spinal cord injury: effects on autonomic outcome

Object

Spinal cord injury (SCI) continues to be a problem without a definitive cure. Research based on improved understanding of the immunological aspects of SCI has revealed targets for treating and ameliorating the extent of secondary injury. Hypertonic saline (HTS), a substance both easy to create and to transport, has been investigated as an immunologically active material that can be used in a clinically relevant interval after injury. In this pilot study, HTS was investigated in a murine model for its abilities to ameliorate secondary injury after a severe spinal cord contusion.

Methods

Female C57Bl/6 mice with severe T8–10 contusion injuries were used as the model subjects. A group of 41 mice were studied in a blinded fashion. Mice received treatments with HTS (HTS, 7.5%) or normal saline solution (NSS, 0.9%) at 2 discreet time points (3 and 24 hours after injury.) A separate group of 9 untreated animals were also used as controls. Animals were assessed for autonomic outcome (bladder function). In a group of 33 mice, histological assessment (cellular infiltration) was also measured.

Results

Bladder function was found to be improved significantly in those treated with HTS compared with those who received NSS and also at later treatment times (24 hours) than at earlier treatment times (3 hours). Decreased cellular infiltration in each group correlated with bladder recovery.

Conclusions

The increased effectiveness of later administration time of the more osmotically active and immunomodulatory substance (HTS) suggests that interaction with events occurring around 24 hours after injury is critical. These events may be related to the invasion of leukocytes peaking at 8–24 hours postinjury and/or the peak benefit time of subject rehydration.

The persistent sodium current blocker riluzole is antiarrhythmic and anti-ischaemic in a pig model of acute myocardial infarction

BACKGROUND

The potential of the cardiac persistent sodium current as a target for protection of the myocardium from ischaemia and reperfusion injury is gaining increasing interest. We have investigated the anti-ischaemic and antiarrhythmic effects of riluzole, a selective INaP blocker, in an open chest pig model of infarction.

METHODS AND PRINCIPAL FINDINGS

The left anterior descending coronary artery (LAD) was ligated in 27 anesthetised pigs (landrace or large white, either sex, 20-35 kg) which had received riluzole (8 mg/kg IP; n = 6), lidocaine (2.5-12 mg/kg bolus plus 0.05-0.24 mg/kg/min; n = 11) or vehicle (n = 10) 50 min prior. Arrhythmias could be delineated into phase 1a (0 to 20 min), phase 1b (20 to 50 min) and phase 2 (from 50 min to termination at 180 min) and were classified as premature ventricular contractions (PVCs), non-sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) (spontaneously reverting within 15 s) or sustained VT or VF (ie. requiring cardioversion at 15 s). Riluzole reduced the average number of all arrhythmias in Phase 2 (PVCs from 484+/-119 to 32+/-13; non sustained arrhythmias from 8.9+/-4.4 to 0.7+/-0.5; sustained arrhythmias from 3.9+/-2.2 to 0.5+/-0.4); lidocaine reduced the average number of non-sustained and sustained arrhythmias (to 0.4+/-0.3 and 0.4+/-0.3 respectively) but not PVCs (to 390+/-234). Riluzole and lidocaine reduced the average number of sustained arrhythmias in phase 1b (from 1.8+/-0.4 to 0.17+/-0.13 (p<0.02) and to 0.55+/-0.26 (p = ns) respectively). Neither lidocaine or riluzole changed the ECG intervals: there was no statistical significance between groups at time zero (just before ligation) for any ECG measure. During the course of the 3 hour period of the ischaemia R-R, and P-R intervals shortened slightly in control and riluzole groups (not significantly different from each other) but not in the lidocaine group (significantly different from control). QRS and QTc did not change appreciably in any group Riluzole reduced the degree of histopathological tissue damage across the infarct zone considerably more than did lidocaine.

CONCLUSIONS

At the doses used, riluzole was at least as effective as lidocaine at reducing the number of episodes of ischaemic VT or VF in pigs, and much more effective at reducing the number of PVCs. We propose that this is related to the ability of riluzole to block cardiac persistent sodium current.

Glial and neuronal control of brain blood flow

Blood flow in the brain is regulated by neurons and astrocytes. Knowledge of how these cells control blood flow is crucial for understanding how neural computation is powered, for interpreting functional imaging scans of brains, and for developing treatments for neurological disorders. It is now recognized that neurotransmitter-mediated signalling has a key role in regulating cerebral blood flow, that much of this control is mediated by astrocytes, that oxygen modulates blood flow regulation, and that blood flow may be controlled by capillaries as well as by arterioles. These conceptual shifts in our understanding of cerebral blood flow control have important implications for the development of new therapeutic approaches.

Clinical and experimental advances in regeneration of spinal cord injury

Spinal cord injury (SCI) is one of the major disabilities dealt with in clinical rehabilitation settings and is multifactorial in that the patients suffer from motor and sensory impairments as well as many other complications throughout their lifetimes. Many clinical trials have been documented during the last two decades to restore damaged spinal cords. However, only a few pharmacological therapies used in clinical settings which still have only limited effects on the regeneration, recovery speed, or retraining of the spinal cord. In this paper, we will introduce recent clinical trials, which performed pharmacological treatments and cell transplantations for patients with SCI, and evaluate recent in vivo studies for the regeneration of injured spinal cord, including stem-cell transplantation, application of neurotrophic factors and suppressor of inhibiting factors, development of biomaterial scaffolds and delivery systems, rehabilitation, and the combinations of these therapies to evaluate what can be appropriately applied in the future to the patients with SCI.

Riluzole protects against cardiac ischaemia and reperfusion damage via block of the persistent sodium current

BACKGROUND AND PURPOSE

Current strategies to ameliorate cardiac ischaemic and reperfusion damage, including block of the sodium-hydrogen exchanger, are therapeutically ineffective. Here we propose a different approach, block of the persistent sodium current (INaP).

EXPERIMENTAL APPROACH

Left ventricular pressure was measured as an index of functional deficit in isolated, Langendorff perfused, hearts from adult rats, subjected to 30 min global ischaemia and reperfusion with vehicle only (control) or riluzole (1-10 microM) in the perfusate. Cell shortening and intracellular Ca2+ concentrations [Ca2+](i) were measured in adult rat isolated myocytes subjected to hypoxia and re-oxygenation. The block of transient and persistent sodium currents by concentrations of riluzole between 0.01 and 100 microM were assessed in rat isolated myocytes using patch clamp techniques.

KEY RESULTS

In perfused hearts, riluzole produced a concentration-dependent cardioprotective action, with minor protection from 1 microM and produced rapid and almost complete recovery upon reperfusion from 3 and 10 microM. In isolated myocytes, riluzole at 3 and 10 microM greatly attenuated or prevented the hypoxia- and reperfusion-induced rise in [Ca2+](i) and the contractile deficit. In patch clamp experiments, riluzole blocked the persistent sodium current with an IC(50) of 2.7 microM, whereas the block of the transient sodium current was only apparent at concentrations above 30 microM.

CONCLUSIONS AND IMPLICATIONS

Riluzole preferentially blocked INaP and was protective in cardiac ischaemia and reperfusion. Thus block of the persistent sodium current would be a viable method of ameliorating cardiac ischaemic and reperfusion damage.

Effect of VEGF treatment on the blood-spinal cord barrier permeability in experimental spinal cord injury: dynamic contrast-enhanced magnetic resonance imaging

Compromised blood-spinal cord barrier (BSCB) is a factor in the outcome following traumatic spinal cord injury (SCI). Vascular endothelial growth factor (VEGF) is a potent stimulator of angiogenesis and vascular permeability. The role of VEGF in SCI is controversial. Relatively little is known about the spatial and temporal changes in the BSCB permeability following administration of VEGF in experimental SCI. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) studies were performed to noninvasively follow spatial and temporal changes in the BSCB permeability following acute administration of VEGF in experimental SCI over a post-injury period of 56 days. The DCE-MRI data was analyzed using a two-compartment pharmacokinetic model. Animals were assessed for open field locomotion using the Basso-Beattie-Bresnahan score. These studies demonstrate that the BSCB permeability was greater at all time points in the VEGF-treated animals compared to saline controls, most significantly in the epicenter region of injury. Although a significant temporal reduction in the BSCB permeability was observed in the VEGF-treated animals, BSCB permeability remained elevated even during the chronic phase. VEGF treatment resulted in earlier improvement in locomotor ability during the chronic phase of SCI. This study suggests a beneficial role of acutely administered VEGF in hastening neurobehavioral recovery after SCI.

Anti-apoptotic and neuroprotective effects of α-lipoic acid on spinal cord ischemia-reperfusion injury in rabbits

PURPOSE

Radical oxygen species produced after injury counteracts antioxidant activity and frequently causes severe oxidative stress for the tissues. Alpha-lipoic acid is a powerful metabolic antioxidant with immunomodulatory effects which provides neuroprotection. The aim of this study is to investigate the neuroprotective and anti-apoptotic effects of alpha-lipoic acid on spinal cord ischemia-reperfusion.

METHODS

Twenty-four adult, male, New Zealand rabbits were divided into sham (n = 8), control (n = 8), and treatment groups (n = 8). The abdominal aorta was clamped for 30 min by an aneurysm clip, approximately 1 cm below the renal artery and 1 cm above the iliac bifurcation in control and treatment groups. Only laparotomy was performed in the sham group. Twenty-five cubic centimeters of saline in control group and 100 mg/kg lipoic acid were administered intraperitoneally in the treatment group after closure of the incision. The animals were killed 48 h later. Spinal cord segments between L2 and S1 were harvested for analysis. Levels of nitric oxide, glutathione, malondialdehyde, advanced oxidation protein products, and superoxide dismutase were analyzed as markers of oxidative stress and inflammation. Caspase-3 activity was analyzed to detect the effect of lipoic acid on apoptosis.

RESULTS

In all measured parameters of oxidative stress, administration of lipoic acid significantly demonstrated favorable effects. Both plasma and tissue levels of nitric oxide, glutathione, malondialdehyde, and advanced oxidation protein products significantly changed in favor of antioxidant activity. There was no significant difference between the plasma superoxide dismutase levels of the groups. Histopathological evaluation of the tissues also demonstrated significant decrease in cellular degeneration and infiltration parameters after lipoic acid administration. However, lipoic acid has no effect on caspase-3 activity.

CONCLUSIONS

Although further studies considering different dose regimens and time intervals are required, the results of the present study prove that alpha-lipoic acid has favorable effects on experimental spinal cord ischemia-reperfusion injury.

Effect of combined treatment with methylprednisolone and Nogo-A monoclonal antibody after rat spinal cord injury

The purpose of this study was to investigate the effects of combination therapy with methylprednisolone (MP) and Nogo-66 antagonistic peptide (NEP1-40) on morphological and functional recovery in adult rats subjected to thoracic compression spinal cord injury (SCI). Animals were randomized into four groups: a trauma control group, an MP group, an NEP1-40 group, and a combined treatment group. The inflammatory reaction, neuronal and oligodendrocyte survival, and ultrastructure were assessed at the injury site. Functional analysis was also performed using Basso, Beattie and Bresnahan (BBB) scoring. Rat behaviour was evaluated regularly up to week 4. NEP1-40 did not alter the beneficial effect of MP on haematogenous inflammatory cell infiltration, while combined treatment resulted in greater neuronal and oligodendrocyte survival compared with monotherapy or control. Combination therapy resulted in better locomotor scores. These results in a clinically-relevant SCI model showed that significant neuroprotection can be obtained by combining an initial acute IV injection of MP with continuously infused NEP1-40.

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

Longitudinal in vivo proton magnetic resonance spectroscopy (1H-MRS) and immunohistochemistry were performed to investigate the tissue degeneration in traumatically injured rat spinal cord rostral and caudal to the lesion epicenter. On 1H-MRS significant decreases in N-acetyl aspartate (NAA) and total creatine (Cr) levels in the rostral, epicenter, and caudal segments were observed by 14 days, and levels remained depressed up to 56 days post-injury (PI). In contrast, the total choline (Cho) levels increased significantly in all three segments by 14 days PI, but recovered in the epicenter and caudal, but not the rostral region, at 56 days PI. Immunohistochemistry demonstrated neuronal cell death in the gray matter, and reactive astrocytes and axonal degeneration in the dorsal, lateral, and ventral white-matter columns. These results suggest delayed tissue degeneration in regions both rostrally and caudally from the epicenter in the injured spinal cord tissue. A rostral-caudal asymmetry in tissue recovery was seen both on MRI-observed hyperintense lesion volume and the Cho, but not NAA and Cr, levels at 56 days PI. These studies suggest that dynamic metabolic changes take place in regions away from the epicenter in injured spinal cord.

Kainate-mediated excitotoxicity induces neuronal death in the rat spinal cord in vitro via a PARP-1 dependent cell death pathway (Parthanatos)

Kainate is an effective excitotoxic agent to lesion spinal cord networks, thus providing an interesting model for investigating basic mechanisms of spinal cord injury. The present study aimed at revealing the type and timecourse of cell death in rat neonatal spinal cord preparations in vitro exposed to 1 h excitotoxic insult with kainate. Substantial numbers of neurons rather than glia showed pyknosis (albeit without necrosis and with minimal apoptosis occurrence) already apparent on kainate washout and peaking 12 h later with dissimilar spinal topography. Neurons appeared to suffer chiefly through a process involving anucleolytic pyknosis mediated by strong activation of poly(ADP-ribose)polymerase-1 (PARP-1) that generated poly ADP-ribose and led to nuclear translocation of the apoptotic inducing factor (AIF) with DNA damage. This process had the hallmarks of parthanatos-type neuronal death. The PARP-1 inhibitor 6-5(H)-phenathridione applied immediately after kainate washout significantly prevented pyknosis in a dose-dependent fashion and inhibited PARP-1-dependent nuclear AIF translocation. Conversely, the caspase-3 inhibitor II was ineffective against neuronal damage. Our results suggest that excitotoxicity of spinal networks was mainly directed to neurons and mediated by PARP-1 death pathways, indicating this mechanism as a potential target for neuroprotection to limit the acute damage to the local circuitry.

Role of plasma membrane calcium ATPase 2 in spinal cord pathology

A number of studies have indicated that plasma membrane calcium ATPases (PMCAs) are expressed in the brain and spinal cord and could play important roles not only in the maintenance of cellular calcium homeostasis but also in the survival and function of central nervous system cells under pathological conditions. The different regional and cellular distributions of the various PMCA isoforms and splice variants in the nervous system and the diverse phenotypes of PMCA knockout mice support the notion that each isoform might play a distinct role. Especially in the spinal cord, the survival of neurons and, in particular, motor neurons could be dependent on PMCA2. This is indicated by the knockdown of PMCA2 in pure spinal cord neuronal cultures that leads to cell death via a decrease in collapsing response mediator protein 1 levels. Moreover, the progressive decline in the number of motor neurons in PMCA2-null mice and heterozygous mice further supports this notion. Therefore, the reported reduction in PMCA2 mRNA and protein levels in the inflamed spinal cord of mice affected by experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis, and after spinal cord contusion injury, suggests that changes in PMCA2 expression could be a cause of neuronal pathology and death during inflammation and injury. Glutamate excitotoxicity mediated via kainate receptors has been implicated in the neuropathology of both EAE and spinal cord injury, and has been identified as a trigger that reduces PMCA2 levels in pure spinal cord neuronal cultures through degradation of the pump by calpain without affecting PMCA2 transcript levels. It remains to be determined which other stimuli modulate PMCA2 mRNA expression in the aforementioned pathological conditions of the spinal cord.

Tumor necrosis factor alpha enhances glutamatergic transmission onto spinal motoneurons

The early stages of spinal cord injury (SCI) start with excitotoxic damage caused by a massive release of glutamate. However, glutamate release is not the only factor to consider. Inflammatory molecules like tumor necrosis factor alpha (TNFalpha), belonging to a group of cytokines initially identified and named for their ability to kill tumor cells, is also a key factor in neuronal death and inflammation. TNFalpha is released from macrophages and activated microglia following a SCI, reaching a peak 1 h after the primary injury. Motoneurons whose survival is necessary for successful rehabilitation are especially vulnerable to the effects of TNFalpha release. While TNFalpha has been postulated to increase glutamatergic synaptic transmission, evidence for this has been indirect. Here, we show using whole-cell recording from lumbar motoneurons that AMPA and NMDA receptor-mediated excitatory postsynaptic currents are rapidly increased following bath application of TNFalpha. Concurrently, the single-channel open probability of AMPA and NMDA channels were also augmented by TNFalpha. Overall, our data lead us to propose the idea that motoneuronal vulnerability to excitotoxicity is not only due to the excessive release of glutamate, but may also be attributable to the increased sensitivity of AMPARs and NMDARs to the proinflammatory factor, TNFalpha, released after SCI.

The functional and neuroprotective actions of Neu2000, a dual-acting pharmacological agent, in the treatment of acute spinal cord injury

The goal of the present study was to examine the neuroprotective and functional significance of targeting both N-methyl-D-aspartate (NMDA) receptor-mediated excitotoxicity and oxidative stress using a dual-acting compound, Neu2000, in rat model of moderate spinal cord injury (SCI). An initial set of experiments was conducted in uninjured rats to study the pharmacokinetic profile of Neu2000 following intraperitoneal and intravenous administration. A second experiment measured free radical production in mitochondria isolated from sham or injured spinal cords of animals receiving vehicle or Neu2000 treatment. A third set of animals was divided into three treatment groups consisting of vehicle treatment, a single dose of Neu2000 (50 mg/kg) administered at 10 min following injury, or a repeated treatment paradigm consisting of a single bolus of Neu2000 at 10 min following injury (50 mg/kg) plus a maintenance dose (25 mg/kg) administered every 24 h for an additional 6 days. Animals were tested once a week for a period of 6 weeks for evidence of locomotor recovery in an open field and kinematic analysis of fine motor control using the DigiGait Image Analysis System. At the end of the testing period, spinal cord reconstruction was performed to obtain nonbiased stereological measures of tissue sparing. The results of this study demonstrate that Neu2000 treatment significantly reduced the production of mitochondrial free radicals and improved locomotor outcomes that were associated with a significant increase in the volume of spared spinal cord tissue.

Proton magnetic resonance spectroscopy reveals neuroprotection by oral minocycline in a nonhuman primate model of accelerated NeuroAIDS

BACKGROUND

Despite the advent of highly active anti-retroviral therapy (HAART), HIV-associated neurocognitive disorders continue to be a significant problem. In efforts to understand and alleviate neurocognitive deficits associated with HIV, we used an accelerated simian immunodeficiency virus (SIV) macaque model of NeuroAIDS to test whether minocycline is neuroprotective against lentiviral-induced neuronal injury.

METHODOLOGY/PRINCIPAL FINDINGS

Eleven rhesus macaques were infected with SIV, depleted of CD8+ lymphocytes, and studied until eight weeks post inoculation (wpi). Seven animals received daily minocycline orally beginning at 4 wpi. Neuronal integrity was monitored in vivo by proton magnetic resonance spectroscopy and post-mortem by immunohistochemistry for synaptophysin (SYN), microtubule-associated protein 2 (MAP2), and neuronal counts. Astrogliosis and microglial activation were quantified by measuring glial fibrillary acidic protein (GFAP) and ionized calcium binding adaptor molecule 1 (IBA-1), respectively. SIV infection followed by CD8+ cell depletion induced a progressive decline in neuronal integrity evidenced by declining N-acetylaspartate/creatine (NAA/Cr), which was arrested with minocycline treatment. The recovery of this ratio was due to increases in NAA, indicating neuronal recovery, and decreases in Cr, likely reflecting downregulation of glial cell activation. SYN, MAP2, and neuronal counts were found to be higher in minocycline-treated animals compared to untreated animals while GFAP and IBA-1 expression were decreased compared to controls. CSF and plasma viral loads were lower in MN-treated animals.

CONCLUSIONS/SIGNIFICANCE

In conclusion, oral minocycline alleviates neuronal damage induced by the AIDS virus.

Striking the target in Wnt-y conditions: intervening in Wnt signaling during cancer progression

Wnt signaling can be divided into three pathways, namely the canonical Wnt/beta-catenin pathway, and the non-canonical (or heretical) Wnt/Ca(2+) and planar cell polarity (PCP) pathways. Although the canonical Wnt/beta-catenin pathway is the best described in cancer, increasing data points to the importance of the heretical Wnt pathways in several aspects of tumor progression. The recent advances in understanding the players and mechanisms by which these Wnt pathways contribute to cancer progression have led to the identification of numerous molecules that are already, or could be considered, targets for cancer therapy.

The hematopoietic factor granulocyte-colony stimulating factor improves outcome in experimental spinal cord injury

Granulocyte-colony stimulating factor (G-CSF) is a potent hematopoietic factor that drives differentiation of neutrophilic granulocytes. We have recently shown that G-CSF also acts as a neuronal growth factor, protects neurons in vitro and in vivo, and has regenerative potential in various neurological disease models. Spinal cord injury (SCI) following trauma or secondary to skeletal instability is a terrible condition with no effective therapies available at present. In this study, we show that the G-CSF receptor is up-regulated upon experimental SCI and that G-CSF improves functional outcome in a partial dissection model of SCI. G-CSF significantly decreases apoptosis in an experimental partial spinal transsection model in the mouse and increases expression of the anti-apoptotic G-CSF target gene Bcl-X(L). In vitro, G-CSF enhances neurite outgrowth and branching capacity of hippocampal neurons. In vivo, G-CSF treatment results in improved functional connectivity of the injured spinal cord as measured by Mn(2+)-enhanced MRI. G-CSF also increased length of the dorsal corticospinal tract and density of serotonergic fibers cranial to the lesion center. Mice treated systemically with G-CSF as well as transgenic mice over-expressing G-CSF in the CNS exhibit a strong improvement in functional outcome as measured by the BBB score and gridwalk analysis. We show that G-CSF improves outcome after experimental SCI by counteracting apoptosis, and enhancing connectivity in the injured spinal cord. We conclude that G-CSF constitutes a promising and feasible new therapy option for SCI.

Effective repair of traumatically injured spinal cord by nanoscale block copolymer micelles

Spinal cord injury results in immediate disruption of neuronal membranes, followed by extensive secondary neurodegenerative processes. A key approach for repairing injured spinal cord is to seal the damaged membranes at an early stage. Here, we show that axonal membranes injured by compression can be effectively repaired using self-assembled monomethoxy poly(ethylene glycol)-poly(d,l-lactic acid) di-block copolymer micelles. Injured spinal tissue incubated with micelles (60 nm diameter) showed rapid restoration of compound action potential and reduced calcium influx into axons for micelle concentrations much lower than the concentrations of polyethylene glycol, a known sealing agent for early-stage spinal cord injury. Intravenously injected micelles effectively recovered locomotor function and reduced the volume and inflammatory response of the lesion in injured rats, without any adverse effects. Our results show that copolymer micelles can interrupt the spread of primary spinal cord injury damage with minimal toxicity.

Reorganization and preservation of motor control of the brain in spinal cord injury: a systematic review

Reorganization of brain function in people with CNS damage has been identified as one of the fundamental mechanisms involved in the recovery of sensorimotor function. Spinal cord injury (SCI) brain mapping studies during motor tasks aim for assessing the reorganization and preservation of brain networks involved in motor control. Revealing the activation of cortical and subcortical brain areas in people with SCI can indicate principal patterns of brain reorganization when the neurotrauma is distal to the brain. This review assessed brain activation after SCI in terms of intensity, volume, and somatotopic localization, as well as preservation of activation during attempted and/or imagined movements. Twenty-five studies meeting the inclusion criteria could be identified in Medline (1980 to January 2008). Relevant characteristics of studies (level of lesion, time after injury, motor task) and mapping techniques varied widely. Changes in brain activation were found in both cortical and subcortical areas of individuals with SCI. In addition, several studies described a shift in the region of brain activation. These patterns appeared to be dynamic and influenced by the level, completeness, and time after injury, as well as extent of clinical recovery. In addition, several aspects of reorganization of brain function following SCI resembled those reported in stroke. This review demonstrates that brain networks involved in different demands of motor control remain responsive even in chronic paralysis. These findings imply that therapeutic strategies aimed at restoring spinal cord function, even in people with chronic SCI, can build on preserved competent brain control.

Computerized classification of neurologic injury based on the international standards for classification of spinal cord injury

BACKGROUND/OBJECTIVE

To develop and test a computer program to accurately score International Standards for Classification of Spinal Cord Injury (ISCSCI) examinations.

METHODS

A computer program was written following the algorithm published in the ISCSCI 2003 manual. Two methods were used to test the computer program's accuracy. First, 94 hand-scored examinations representing 25 different patients were entered into the program. Differences between hand-scored examinations and computer-scored examinations were evaluated for accuracy. Second, all case examples from the ISCSCI manual were entered into the computer program to verify its accuracy.

RESULTS

Of the 94 hand-scored examinations, the computer detected all incorrectly scored examinations. Furthermore, the computer scoring agreed with every examination's scores that were correctly calculated by hand. Of the hand-scored examinations, 10% of sensory total scores and 4% of motor scores were incorrect. For sensory level and motor level, there were errors in 9% and 26% of hand-scored examinations, respectively; 13% of hand-scored examinations had incorrectly assigned ASIA Impairment Scale classification.

CONCLUSION

This study showed that the computer program we developed was effective in correctly scoring ISCSCI examinations and was able to detect errors in hand-scored examinations.

Ibuprofen enhances recovery from spinal cord injury by limiting tissue loss and stimulating axonal growth

The GTP-binding protein RhoA regulates microfilament dynamics in many cell types and mediates the inhibition of axonal regeneration by myelin and chondroitin sulfate proteoglycans. Unlike most other nonsteroidal anti-inflammatory drugs, ibuprofen suppresses basal RhoA activity (Zhou et al., 2003). A recent report suggested that ibuprofen promotes corticospinal axon regeneration after spinal cord injury (Fu et al., 2007). Here, we confirm that ibuprofen reduces ligand-induced Rho signaling and myelin-induced inhibition of neurite outgrowth in vitro. Following 4 weeks of subcutaneous administration of ibuprofen, beginning 3 days after spinal cord contusion, animals recovered walking function to a greater degree, with twice as many rats achieving a hind limb weight-bearing status. We examined the relative role of tissue sparing, axonal sprouting, and axonal regeneration in the action of ibuprofen. Histologically, ibuprofen-treated animals display an increase in spared tissue without an alteration in astrocytic or microglial reaction. Ibuprofen increases axonal sprouting from serotonergic raphespinal axons, and from rostral corticospinal fibers in the injured spinal cord, but does not permit caudal corticospinal regeneration after spinal contusion. Treatment of mice with complete spinal cord transection demonstrates long-distance raphespinal axon regeneration in the presence of ibuprofen. Thus, administration of ibuprofen improves the recovery of rats from a clinically relevant spinal cord trauma by protecting tissue, stimulating axonal sprouting, and allowing a minor degree of raphespinal regeneration.

Acrolein scavenging: a potential novel mechanism of attenuating oxidative stress following spinal cord injury

It has long been established that oxidative stress plays a critical role in the pathophysiology of spinal cord injury, and represents an important target of therapeutic intervention following the initial trauma. However, free radical scavengers have been largely ineffective in clinical trials, and as such a novel target to attenuate oxidative stress is highly warranted. In addition to free radicals, peroxidation of lipid membranes following spinal cord injury (SCI) produces reactive aldehydes such as acrolein. Acrolein is capable of depleting endogenous antioxidants such as glutathione, generating free radicals, promoting oxidative stress, and damaging proteins and DNA. Acrolein has a significantly longer half-life than the transient free radicals, and thus may represent a potentially better target of therapeutic intervention to attenuate oxidative stress. There is growing evidence, from our lab and others, to suggest that reactive aldehydes such as acrolein play a critical role in oxidative stress and SCI. The focus of this review is to summarize the cellular and biochemical mechanisms of acrolein-induced membrane damage, mitochondrial injury, oxidative stress, cell death, and functional loss. Evidence will also be presented to suggest that acrolein scavenging may be a novel means of therapeutic intervention to attenuate oxidative stress and improve recovery following traumatic SCI.

Treatment of rat spinal cord injury with a Rho-kinase inhibitor and bone marrow stromal cell transplantation

In light of reports that the administration of fasudil, a Rho-kinase inhibitor, improved rats locomotor abilities following spinal cord injury, we hypothesized that combining fasudil with another type of therapy, such as stem cell transplantation, might further improve the level of locomotor recovery. Bone marrow stromal cells (BMSCs) are readily available for stem cell therapy. In the present study, we examined whether fasudil combined with BMSC transplantation would produce synergistic effects on recovery. Adult female Sprague-Dawley rats were subjected to spinal cord contusion injury at the T10 vertebral level using an IH impactor (200 Kdyn). Immediately after contusion, they were administrated fasudil intrathecally for 4 weeks. GFP rat-derived BMSCs (2.5x10(6)) were injected into the lesion site 14 days after contusion. Locomotor recovery was assessed for 9 weeks with BBB scoring. Sensory tests were conducted at 8 weeks. Biotinylated dextran amine (BDA) was injected into the sensory-motor cortex at 9 weeks. In addition to an untreated control group, the study also included a fasudil-only group and a BMSC-only group in order to compare the effects of combined therapy vs. single-agent therapy. Animals were perfused transcardially 11 weeks after contusion, and histological examinations were performed. The combined therapy group showed statistically better locomotor recovery than the untreated control group at 8 and 9 weeks after contusion. Neither of the two single-agent treatments improved open field locomotor function. Sensory tests showed no statistically significant difference by treatment. Histological and immunohistochemical studies provided some supporting evidence for better locomotor recovery following combined therapy. The average area of the cystic cavity was significantly smaller in the fasudil+BMSC group than in the control group. The number of 5-HT nerve fibers was significantly higher in the fasudil+BMSC group than in the control group on the rostral side of the lesion site. BDA-labeled fibers on the caudal side of the lesion epicenter were observed only in the fasudil+BMSC group. On the other hand, only small numbers of GFP-labeled grafted cells remained 9 weeks after transplantation, and these were mainly localized at the site of injection. Double immunofluorescence studies showed no evidence of differentiation of grafted BMSCs into glial cells or neurons. The Rho-kinase inhibitor fasudil combined with BMSC transplantation resulted in better locomotor recovery than occurred in the untreated control group. However, the data failed to demonstrate significant synergism from combined therapy compared with the levels of recovery following single-agent treatment.

Resection of glial scar following spinal cord injury

While many studies have focused on modulating the immune response and enhancing axonal regeneration after spinal cord injury (SCI), there is limited work being performed on evaluating the role of glial scar in SCI. We sought to evaluate the effects of glial scar resection in contusion models and dorsal hemisection models of SCI. At 1-week postinjury, 2 mm of glial scar was excised from specimens in one of the two groups from each injury model. Functional outcome was measured weekly using the Basso, Beattie, Bresnahan (BBB) Locomotor Rating Scale along with histologic evaluation of spinal cord tracts to determine axonal regeneration. Within the dorsal hemisection model, there was no significant difference in recovery for animals that underwent glial scar excision versus animals that did not have scar excision (p = 0.61). Animals subjected to the contusion model, however, demonstrated lower BBB scores in the glial resection group during the earlier postoperative periods (< 4 weeks; p < 0.05). Histological analysis revealed no axons within the glial resection contusion model, and moderate axonal growth within the nonresection contusion group and both hemisection groups (p > 0.05 for differences among the three groups). While glial scar may serve to stabilize the preserved axonal tracts and thereby permit modest recovery in a contusion model of SCI, it may be of less importance with a dorsal hemisection model. These experiments highlight that basic biologic processes following SCI may vary tremendously based on the injury mechanism and that the role of glial scar in spinal cord regeneration must be elucidated.

Acute rolipram/thalidomide treatment improves tissue sparing and locomotion after experimental spinal cord injury

Traumatic spinal cord injury (SCI) causes severe and permanent functional deficits due to the primary mechanical insult followed by secondary tissue degeneration. The cascade of secondary degenerative events constitutes a range of therapeutic targets which, if successfully treated, could significantly ameliorate functional loss after traumatic SCI. During the early hours after injury, potent pro-inflammatory cytokines, including tumor necrosis factor alpha (TNF-alpha) and interleukin-1 beta (IL-1beta) are synthesized and released, playing key roles in secondary tissue degeneration. In the present investigation, the ability of rolipram and thalidomide (FDA approved drugs) to reduce secondary tissue degeneration and improve motor function was assessed in an experimental model of spinal cord contusion injury. The combined acute single intraperitoneal administration of both drugs attenuated TNF-alpha and IL-1beta production and improved white matter sparing at the lesion epicenter. This was accompanied by a significant (2.6 point) improvement in the BBB locomotor score by 6 weeks. There is, at present, no widely accepted intervention strategy that is appropriate for the early treatment of human SCI. The present data suggest that clinical trials for the acute combined application of rolipram and thalidomide may be warranted. The use of such "established drugs" could facilitate the early initiation of trials.

Protection and repair of the injured spinal cord: a review of completed, ongoing, and planned clinical trials for acute spinal cord injury

Over the past 2 decades, advances in understanding the pathophysiology of spinal cord injury (SCI) have stimulated the recent emergence of several therapeutic strategies that are being examined in Phase I/II clinical trials. Ten randomized controlled trials examining methylprednisolone sodium succinate, tirilizad mesylate, monosialotetrahexosylganglioside, thyrotropin releasing hormone, gacyclidine, naloxone, and nimodipine have been completed. Although the primary outcomes in these trials were laregely negative, a secondary analysis of the North American Spinal Cord Injury Study II demonstrated that when administered within 8 hours of injury, methylprednisolone sodium succinate was associated with modest clinical benefits, which need to be weighed against potential complications. Thyrotropin releasing hormone (Phase II trial) and monosialotetrahexosylganglioside (Phase II and III trials) also showed some promise, but we are unaware of plans for future trials with these agents. These studies have, however, yielded many insights into the conduct of clinical trials for SCI. Several current or planned clinical trials are exploring interventions such as early surgical decompression (Surgical Treatment of Acute Spinal Cord Injury Study) and electrical field stimulation, neuroprotective strategies such as riluzole and minocycline, the inactivation of myelin inhibition by blocking Nogo and Rho, and the transplantation of various cellular substrates into the injured cord. Unfortunately, some experimental and poorly characterized SCI therapies are being offered outside a formal investigational structure, which will yield findings of limited scientific value and risk harm to patients with SCI who are understandably desperate for any intervention that might improve their function. Taken together, recent advances suggest that optimism for patients and clinicians alike is justified, as there is real hope that several safe and effective therapies for SCI may become available over the next decade.