Emerging drugs for spinal cord injury

Functional improvement in individuals with chronic spinal cord injury treated with 4-aminopyridine: A systematic review

Study design

Systematic review.

Objective

To provide current evidence on the efficacy of 4-aminopyridine (4-AP) to bring about functional improvement in individuals with chronic traumatic spinal cord injury (SCI).

Methods

The Medline (PubMed), Web of Science and SCOPUS databases were systematically searched for relevant articles on the efficacy of 4-AP to treat SCI, from the dates such articles were first published until May 2022. Full-text versions of all the articles selected were examined independently by two reviewers. Methodological quality was rated using the Modified Jadad Scale, and risk of bias was assessed with the RoB-2 test. Data extracted included human models/types, PRISMA assessment protocols, and the results of each study. Descriptive syntheses are provided.

Results

In total, 28 articles were initially identified, 10 of which were included after screening. Most of the studies reviewed reported some degree of patient improvement in one or more of the following parameters: motor, sensitivity and sexual function, sphincter control, spasticity, ability to function independently, quality of life, central motor conduction, pain, and pulmonary function.

Conclusions

This review confirms the efficacy of 4-AP in improving several conditions resulting from SCI but further research on this topic is warranted. Additional randomized clinical trials with 4-AP involving larger sample sizes are needed, as are consistent outcome measures in order to obtain adequate data for analysis with a view to enhance treatment benefits.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=334835, PROSPERO CRD42022334835.

Microtubule Dynamics Following Central and Peripheral Nervous System Axotomy

Disturbance in the neuronal network leads to instability in the microtubule (MT) railroad of axons, causing hindrance in the intra-axonal transport and making it difficult to re-establish the broken network. Peripheral nervous system (PNS) neurons can stabilize their MTs, leading to the formation of regeneration-promoting structures called "growth cones". However, central nervous system (CNS) neurons lack this intrinsic reparative capability and, instead, form growth-incompetent structures called "retraction bulbs", which have a disarrayed MT network. It is evident from various studies that although axonal regeneration depends on both cell-extrinsic and cell-intrinsic factors, any therapy that aims at axonal regeneration ultimately converges onto MTs. Understanding the neuronal MT dynamics will help develop effective therapeutic strategies in diseases where the MT network gets disrupted, such as spinal cord injury, traumatic brain injury, multiple sclerosis, and amyotrophic lateral sclerosis. It is also essential to know the factors that aid or inhibit MT stabilization. In this review, we have discussed the MT dynamics postaxotomy in the CNS and PNS, and factors that can directly influence MT stability in various diseases.

Neuroimmunological therapies for treating spinal cord injury: Evidence and future perspectives

Spinal cord injury (SCI) has a complex pathophysiology. Following the initial physical trauma to the spinal cord, which may cause vascular disruption, hemorrhage, mechanical injury to neural structures and necrosis, a series of biomolecular cascades is triggered to evoke secondary injury. Neuroinflammation plays a major role in the secondary injury after traumatic SCI. To date, the administration of systemic immunosuppressive medications, in particular methylprednisolone sodium succinate, has been the primary pharmacological treatment. This medication is given as a complement to surgical decompression of the spinal cord and maintenance of spinal cord perfusion through hemodynamic augmentation. However, the impact of neuroinflammation is complex with harmful and beneficial effects. The use of systemic immunosuppressants is further complicated by the natural onset of post-injury immunosuppression, which many patients with SCI develop. It has been hypothesized that immunomodulation to attenuate detrimental aspects of neuroinflammation after SCI, while avoiding systemic immunosuppression, may be a superior approach. To accomplish this, a detailed understanding of neuroinflammation and the systemic immune responses after SCI is required. Our review will strive to achieve this goal by first giving an overview of SCI from a clinical and basic science context. The role that neuroinflammation plays in the pathophysiology of SCI will be discussed. Next, the positive and negative attributes of the innate and adaptive immune systems in neuroinflammation after SCI will be described. With this background established, the currently existing immunosuppressive and immunomodulatory therapies for treating SCI will be explored. We will conclude with a summary of topics that can be explored by neuroimmunology research. These concepts will be complemented by points to be considered by neuroscientists developing therapies for SCI and other injuries to the central nervous system.

Age as a determinant of inflammatory response and survival of glia and axons after human traumatic spinal cord injury

Despite the shift in the demographics of traumatic spinal cord injury (SCI) with increased proportion of injuries in the elderly, little is known on the potential effects of old age on the pathobiology of SCI. Since there is an assumption that age adversely affects neural response to SCI, this study examines the clinically relevant question on whether age is a key determinant of inflammatory response, oligodendroglial apoptosis and axonal survival after traumatic SCI. This unique study includes post-mortem spinal cord tissue from 64 cases of SCI (at cervical or high-thoracic levels) and 38 control cases without CNS injury. Each group was subdivided into subgroups of younger and elderly individuals (65 years of age or older at the SCI onset). The results of this study indicate that age at the SCI onset does not adversely affect the cellular inflammatory response to, oligodendroglial apoptosis and axonal survival after SCI. These results support the conclusion that elderly individuals have similar neurobiological responses to SCI as younger people and, hence, treatment decisions should be based on an assessment of the individual patient and not an arbitrary assumption that "advanced age" should exclude patients with an acute SCI from access to advanced care and translational therapies.

Neuroprotective effects of sildenafil in experimental spinal cord injury in rabbits

Neuroprotective agents such as methylprednisolone and sildenafil may limit damage after spinal cord injury. We evaluated the effects of methylprednisolone and sildenafil on biochemical and histologic changes after spinal cord injury in a rabbit model. Female New Zealand rabbits (32 rabbits) were allocated to 4 equal groups: laminectomy only (sham control) or laminectomy and spinal trauma with no other treatment (trauma control) or treatment with either methylprednisolone or sildenafil. Gelsolin and caspase-3 levels in cerebrospinal fluid and plasma were determined, and spinal cord histology was evaluated at 24 hours after trauma. There were no differences in mean cerebrospinal fluid or plasma levels of caspase-3 between the groups or within the groups from 0 to 24 hours after injury. From 0 to 24 hours after trauma, mean cerebrospinal fluid gelsolin levels significantly increased in the sildenafil group and decreased in the sham control and the trauma control groups. Mean plasma gelsolin level was significantly higher at 8 and 24 hours after trauma in the sildenafil than other groups. Histologic examination indicated that general structural integrity was better in the methylprednisolone in comparison with the trauma control group. General structural integrity, leptomeninges, white and grey matter hematomas, and necrosis were significantly improved in the sildenafil compared with the trauma control group. Caspase-3 levels in the cerebrospinal fluid and blood were not increased but gelsolin levels were decreased after spinal cord injury in trauma control rabbits. Sildenafil caused an increase in gelsolin levels and may be more effective than methylprednisolone at decreasing secondary damage to the spinal cord. 

The volatile anesthetic methoxyflurane protects motoneurons against excitotoxicity in an in vitro model of rat spinal cord injury

Neuroprotection of the spinal cord during the early phase of injury is an important goal to determine a favorable outcome by prevention of delayed pathological events, including excitotoxicity, which otherwise extend the primary damage and amplify the often irreversible loss of motor function. While intensive care and neurosurgical intervention are important treatments, effective neuroprotection requires further experimental studies focused to target vulnerable neurons, particularly motoneurons. The present investigation examined whether the volatile general anesthetic methoxyflurane might protect spinal locomotor networks from kainate-evoked excitotoxicity using an in vitro rat spinal cord preparation as a model. The protocols involved 1h excitotoxic stimulation on day 1 followed by electrophysiological and immunohistochemical testing on day 2. A single administration of methoxyflurane applied together with kainate (1h), or 30 or even 60 min later prevented any depression of spinal reflexes, loss of motoneuron excitability, and histological damage. Methoxyflurane per se temporarily decreased synaptic transmission and motoneuron excitability, effects readily reversible on washout. Spinal locomotor activity recorded as alternating electrical discharges from lumbar motor pools was fully preserved on the second day after application of methoxyflurane together with (or after) kainate. These data suggest that a volatile general anesthetic could provide strong electrophysiological and histological neuroprotection that enabled expression of locomotor network activity 1 day after the excitotoxic challenge. It is hypothesized that the benefits of early neurosurgery for acute spinal cord injury (SCI) might be enhanced if, in addition to injury decompression and stabilization, the protective role of general anesthesia is exploited.

Meglumine cyclic adenylate improves neurological function following acute spinal cord injury in rats

Elevation of intracellular cyclic adenosine monophosphate (cAMP) levels facilitates recovery following spinal injury by suppressing secondary pathology and promoting axonal regeneration. However, this treatment strategy is limited by lack of effective and tolerable clinical agents. The present study examined the effects of meglumine cyclic adenylate (MCA) on neurological recovery, cAMP concentration, adenylate cyclase 3 (AC3) activity and phosphodiesterase 4D (PDE4D) activity during early stage acute spinal cord injury (SCI) in rats. A total of 48 Sprague‑Dawley rats were randomly assigned to groups A, B or C, each consisting of 16 animals. SCI was induced by Allen's method using a 7 g x 3 cm extradural weight‑drop impact on spinal cord segment T11. A total of 30 min following SCI, group A received a single 30 mg/kg‑bw i.p. dose of methylprednisolone, group B received 2 mg/kg‑bw i.p. MCA daily for seven days and group C were administered an equal volume of normal saline. Seven days following SCI, the spinal cord samples from eight rats per group were obtained to measure the cAMP concentration, and the activities of AC3 and PDE4D. The remaining eight rats per group were used for behavioral assessments using the inclined plane stability test and Gale scale for up to six weeks post‑SCI. The drug‑treated groups A and B had higher cAMP concentrations and AC3 activities but lower PDE4D activities at the lesion sites, as well as superior behavioral scores post‑SCI compared with the vehicle‑treated group C (P<0.05). Furthermore, cAMP was higher in group B than in group A (P<0.05). It was concluded that MCA may serve as an effective SCI treatment by activating AC3 and suppressing PDE4D.

Surgical decompression in acute spinal cord injury: A review of clinical evidence, animal model studies, and potential future directions of investigation

The goal for treatment in acute spinal cord injury (SCI) is to reduce the extent of secondary damage and facilitate neurologic regeneration and functional recovery. Although multiple studies have investigated potential new therapies for the treatment of acute SCI, outcomes and management protocols aimed at ameliorating neurologic injury in patients remain ineffective. More recent clinical and basic science research have shown surgical interventions to be a potentially valuable modality for treatment; however, the role and timing of surgical decompression, in addition to the optimal surgical intervention, remain one of the most controversial topics pertaining to surgical treatment of acute SCI. As an increasing number of potential treatment modalities emerge, animal models are pivotal for investigating its clinical application and translation into human trials. This review critically appraises the available literature for both clinical and basic science studies to highlight the extent of investigation that has occurred, specific therapies considered, and potential areas for future research.

Riluzole for the treatment of acute traumatic spinal cord injury: rationale for and design of the NACTN Phase I clinical trial

In the immediate period after traumatic spinal cord injury (SCI) a variety of secondary injury mechanisms combine to gradually expand the initial lesion size, potentially leading to diminished neurological outcomes at long-term follow-up. Riluzole, a benzothiazole drug, which has neuroprotective properties based on sodium channel blockade and mitigation of glutamatergic toxicity, is currently an approved drug that attenuates the extent of neuronal degeneration in patients with amyotrophic lateral sclerosis. Moreover, several preclinical SCI studies have associated riluzole administration with improved functional outcomes and increased neural tissue preservation. Based on these findings, riluzole has attracted considerable interest as a potential neuroprotective drug for the treatment of SCI. Currently, a Phase I trial evaluating the safety and pharmacokinetic profile of riluzole in human SCI patients is being conducted by the North American Clinical Trials Network (NACTN) for Treatment of Spinal Cord Injury. The current review summarizes the existing preclinical and clinical literature on riluzole, provides a detailed description of the Phase I trial, and suggests potential opportunities for future investigation. Clinical trial registration no.: NCT00876889.

Drug-eluting microfibrous patches for the local delivery of rolipram in spinal cord repair

Spinal cord injury (SCI) remains a major challenge for regenerative medicine. Following SCI, axon growth inhibitors and other inflammatory responses prevent functional recovery. Previous studies have demonstrated that rolipram, an anti-inflammatory and cyclic adenosine monophosphate preserving small molecule, improves spinal cord regeneration when delivered systemically. However, more recent studies showed that rolipram has some adverse effects in spinal cord repair. Here, we developed a drug-delivery platform for the local delivery of rolipram into the spinal cord. The potential of drug-eluting microfibrous patches for continuous delivery of high and low-dose rolipram concentrations was characterized in vitro. Following C5 hemisections, athymic rats were treated with patches loaded with low and high doses of rolipram. In general, animals treated with low-dose rolipram experienced greater functional and anatomical recovery relative to all other groups. Outcomes from the high-dose rolipram treatment were similar to those with no treatment. In addition, high-dose treated animals experienced reduced survival rates suggesting that systemic toxicity was reached. With the ability to control the release of drug dosage locally within the spinal cord, drug-eluting microfibrous patches demonstrate the importance of appropriate local release-kinetics of rolipram, proving their usefulness as a therapeutic platform for the study and repair of SCI.

Targeting mTOR as a novel therapeutic strategy for traumatic CNS injuries

The adult central nervous system (CNS) has a remarkable ability to repair itself. However, severe brain and spinal cord injuries (SCIs) cause lasting disability and there are only a few therapies that can prevent or restore function in such cases. In this review, we provide an overview of traumatic CNS injuries and discuss several emerging pharmacological options that have shown promise in preclinical and early clinical studies. We highlight therapies that modulate mammalian target of rapamycin (mTOR) signaling, a pathway that is well known for its roles in cell growth, metabolism and cancer. Interestingly, this pathway is also gaining newfound attention for its role in CNS repair and regeneration.

The delayed post-injury administration of soluble fas receptor attenuates post-traumatic neural degeneration and enhances functional recovery after traumatic cervical spinal cord injury

Spinal cord injury (SCI) is a devastating condition that currently lacks clinically-relevant and effective neuroprotective therapeutic options. Optimal therapeutic agents for clinical translation should show efficacy in a cervical compression/contusion model using a clinically-relevant post-injury therapeutic time window. To date, few compounds have met that rigorous standard. The objective of this work was to evaluate the efficacy of delayed post-injury administration of soluble Fas receptor (sFasR) via intrathecal catheter following acute cervical SCI in a clinically-relevant contusion/compression model. Female Wistar rats were given a C7-T1 moderately severe clip compression injury, followed by either 8-h or 24-h delayed treatment initiation. Long-term neurobehavioral analysis of motor recovery and neuropathic pain development was undertaken. The extent of oligodendrocyte and neuron survival was assessed in peri-lesional cord sections 8 weeks post-SCI. This was complemented by an evaluation of the level of tissue preservation at and adjacent to the site of injury. In animals treated with sFasR delayed 8 h post-injury, significant behavioral effects were observed, coinciding with enhanced cell survival, peri-lesional tissue sparing, and enhanced integrity of descending fiber tracts compared to control treatments. Animals treated with sFasR delayed by 24 h showed more modest improvements in behavioral recovery, and had consistent improvements in cell survival and tissue preservation. This work has shown for the first time that the Fas-mediated apoptotic pathway can be therapeutically targeted in a clinically-relevant time window post-SCI.

A quantitative analysis of clinical trial designs in spinal cord injury based on ICCP guidelines

Clinical studies of spinal cord injury (SCI) have evolved into multidisciplinary programs that investigate multiple types of neurological deficits and sequelae. In 2007, the International Campaign for Cures of SCI Paralysis (ICCP) proposed best practices for interventional trial designs, end-points, and inclusion criteria. Here we quantitatively assessed the extent to which SCI trials follow ICCP guidelines and reflect the overall patient population. We obtained data for all 288 SCI trials in ClinicalTrials.gov. We calculated summary statistics and observed trends pre-2007 versus 2007 onward. To compare the trial population to the overall SCI population, we obtained statistics from the National SCI Statistical Center. We generated tag clouds to describe heterogeneous trial outcomes. Most interventional studies were randomized (147, 73.1%), and utilized active (55, 36.7%) or placebo controls (49, 32.7%), both increasing trends (p=0.09). Most trials were open label (116, 53.5%), rather than double- (62, 28.6%) or single-blinded (39, 18.0%), but blinding has increased (p=0.01). Tag clouds of outcomes suggest an emphasis on assessment using scores and scales. Inclusion criteria related to American Spinal Injury Association (ASIA) status and neurological level allowed inclusion of most SCI patients. Age inclusion criteria were most commonly 18-65 or older. Consistent with ICCP recommendations, most trials were randomized and controlled, and blinding has increased. Age inclusion criteria skew older than the overall population. ASIA status criteria reflect the population, but neurological lesion criteria could be broadened. Investigators should make trial designs and results available in a complete manner to enable comparisons of populations and outcomes.

A systematic review of the effects of pharmacological agents on walking function in people with spinal cord injury

Studies of spinalized animals indicate that some pharmacological agents may act on receptors in the spinal cord, helping to produce coordinated locomotor movement. Other drugs may help to ameliorate the neuropathological changes resulting from spinal cord injury (SCI), such as spasticity or demyelination, to improve walking. The purpose of this study was to systematically review the effects of pharmacological agents on gait in people with SCI. A keyword literature search of articles that evaluated the effects of drugs on walking after SCI was performed using the databases MEDLINE/PubMed, CINAHL, EMBASE, PsycINFO, and hand searching. Two reviewers independently evaluated each study, using the Physiotherapy Evidence Database (PEDro) tool for randomized clinical trials (RCTs), and the modified Downs & Black scale for all other studies. Results were tabulated and levels of evidence were assigned. Eleven studies met the inclusion criteria. One RCT provided Level 1 evidence that GM-1 ganglioside in combination with physical therapy improved motor scores, walking velocity, and distance better than placebo and physical therapy in persons with incomplete SCI. Multiple studies (levels of evidence 1-5) showed that clonidine and cyproheptadine may improve locomotor function and walking speed in severely impaired individuals with incomplete SCI. Gains in walking speed associated with GM-1, cyproheptadine, and clonidine are low compared to those seen with locomotor training. There was also Level 1 evidence that 4-aminopyridine and L-dopa were no better than placebo in helping to improve gait. Two Level 5 studies showed that baclofen had little to no effect on improving walking in persons with incomplete SCI. There is limited evidence that pharmacological agents tested so far would facilitate the recovery of walking after SCI. More studies are needed to better understand the effects of drugs combined with gait training on walking outcomes in people with SCI.

Emerging approaches to the surgical management of acute traumatic spinal cord injury

Traumatic, spinal cord injury (SCI) is a potentially catastrophic event causing major impact at both a personal and societal level. To date, virtually all therapies that have shown promise at the preclinical stage of study have failed to translate into clinically effective treatments. Surgery is performed in the setting of SCI, with the goals of decompressing the spinal cord and restoring spinal stability. Although a consensus regarding the optimal timing of surgical decompression for SCI has not been reached, much of the preclinical and clinical evidence, as well as a recent international survey of spine surgeons, support performing early surgery (<24 hours). Results of the multicenter, Surgical Trial in Acute Spinal Cord Injury Study (STASCIS), expected later this year, should further clarify this important management issue. The overall goal of this review is to provide an update regarding the current status of surgical therapy for traumatic SCI by reviewing relevant pathophysiology, laboratory, and clinical evidence, as well as to introduce radiologic and clinical tools that aid in the surgical decision-making process.

Immunoglobulin G: a potential treatment to attenuate neuroinflammation following spinal cord injury

Introduction

Spinal cord injury (SCI) is caused by two related but mechanistically distinct events: the primary injury to the spinal cord is caused by a mechanic trauma; the secondary injury is a cascade of cellular and molecular events that exacerbates the initial damage.

Materials and Methods

Neuroinflammation, an important event in the secondary injury cascade, is critical in the clearance of cellular debris after SCI. However, leukocytes and microglia, recruited to the injury site during neuroinflammation, can exacerbate the initial damage following SCI by secreting reactive oxygen species, matrix-metalloproteinase, and proinflammatory cytokines. Therefore, attenuating the activity of leukocytes and microglia is an attractive therapeutic strategy to reduce the neurological deficit associated with SCI.

Discussion

In this regard, immunoglobulin G (IgG) is a potential treatment candidate. IgG has been used clinically to treat autoimmune disease and has been demonstrated to attenuate the activities of leukocytes and microglia. In this review, we discuss the potential use of IgG for SCI based on the current understanding of the immune-modulating mechanism of IgG and the role of neuroinflammation in SCI.

Emerging repair, regeneration, and translational research advances for spinal cord injury

STUDY DESIGN

Literature review of basic scientific and clinical research in spinal cord injury (SCI).

OBJECTIVE

To provide physicians with an overview of the neurobiologic challenges of SCI, the current status of investigation for novel therapies that have been translated to human clinical trials, and the preclinical, scientific basis for each of these therapies.

SUMMARY OF BACKGROUND DATA

An abundance of recent scientific and clinical research activity has revealed numerous insights into the neurobiology of SCI, and has generated an abundance of potential therapies. An increasing number of such therapies are being translated into human SCI trials. Clinicians who attend to SCI patients are increasingly asked about potential treatments and clinical trials.

METHODS

Published data review of novel treatments that are either currently in human clinical trials for acute SCI or about to initiate clinical evaluation.

RESULTS

A number of treatments have bridged the "translational gap" and are currently either in the midst of human SCI trials, or are about to begin such clinical evaluation. These include minocycline, Cethrin, anti-Nogo antibodies, systemic hypothermia, Riluzole, magnesium chloride in polyethylene glycol, and human embryonic stem cell derived oligodendrocyte progenitors. A systematic review of the preclinical literature on these specific therapies reveals promising results in a variety of different SCI injury models.

CONCLUSION

The SCI community is encouraged by the progression of novel therapies from "bench to bedside" and the initiation of clinical trials for a number of different treatments. The task of clinical evaluation, however, is substantial, and many years will be required before the actual efficacy of the treatments currently in evaluation will be determined.

The challenges of managing spine and spinal cord injuries: an evolving consensus and opportunities for change

The current Spine Focus Issue reflects the collective efforts of members of the Spine Trauma Study Group, and seeks to summarize as well as critically evaluate many of the key controversies related to the management of spinal trauma and spinal cord injury. Some of the topics discussed in this issue include the optimal timing for surgical intervention in spinal cord injury and central cord syndrome, the optimal treatment for both elderly and skeletally mature individuals with odontoid process fractures, management of pediatric spine trauma, rehabilitation strategies for the spinal injured patient, return to play guidelines, and variations in international practice patterns for the management of common spine trauma scenarios. The current Spine issue serves as an update to clinicians on these topics as well as a framework for stimulating new discussion and research in the field as a whole.

Assessment of disability in patients with acute traumatic spinal cord injury: a systematic review of the literature

Given the importance of accurately and reliably assessing disability in future clinical trials, which will test therapeutic strategies in acute spinal cord injury (SCI), we sought to appraise comprehensively studies that focused on the psychometric properties (i.e., reliability, validity, and responsiveness) of all previously used outcome measures in the SCI population. The search strategy included Medline, CINAHL, EMBASE, and Cochrane databases. Two reviewers independently assessed each study regarding eligibility, level of evidence (using Sackett's criteria), and quality. Of 363 abstracts captured in our search, 36 full articles fulfilled the inclusion and exclusion criteria. Eight different outcome measures were used to assess disability in the SCI population, including Functional Independence Measure (FIM), Spinal cord Injury Measure (SCIM), Walking Index for Spinal Cord Injury (WISCI), Quadriplegia Index of Function (QIF), Modified Barthel Index (MBI), Timed Up & Go (TUG), 6-min walk test (6MWT), and 10-m walk test (10MWT). While 19 of 36 studies provided level-4 evidence, the remaining 17 articles were classified as level-2b evidence. Most of the instruments showed convergent construct validity in the SCI population, but criterion validity was not examined due to the lack a gold standard for assessment of disability. All instruments were tested in the rehabilitation and/or community setting, but only FIM was examined in the acute care setting. Based on our results of quality assessment, the SCIM has the most appropriate performance regarding the instrument's psychometric properties. Nonetheless, further investigations are required to confirm the adequate performance of the SCIM as a comprehensive measure of functional recovery in patients with SCI in rehabilitative care. The expert panel of the Spinal Cord Injury Solutions Network (SCISN) that participated in the modified Delphi process endorsed these conclusions.

Nanofibrous Patches for Spinal Cord Regeneration

The difficulty in spinal cord regeneration is related to the inhibitory factors for axon growth and the lack of appropriate axon guidance in the lesion region. Here we developed scaffolds with aligned nanofibers for nerve guidance and drug delivery in spinal cord. Blended polymers including Poly (l-lactic acid) (PLLA) and Poly (lactide-co-glycolide) (PLGA) were used to electrospin nanofibrous scaffolds with two-layer structure: aligned nanofibers in the inner layer and random nanofibers in the outer layer. Rolipram, a small molecule that can enhance cAMP activity in neurons and suppress inflammatory responses, was immobilized onto nanofibers. To test the therapeutic effects of nanofibrous scaffolds, the nanofibrous scaffolds loaded with rolipram were used to bridge the hemisection lesion in 8-week old athymic rats. The scaffolds with rolipram increased axon growth through the scaffolds and in the lesion, promoted angiogenesis through the scaffold, and decreased the population of astrocytes and chondroitin sulfate proteoglycans in the lesion. Locomotor scale rating analysis showed that the scaffolds with rolipram significantly improved hindlimb function after 3 weeks. This study demonstrated that nanofibrous scaffolds offered a valuable platform for drug delivery for spinal cord regeneration.

The evidence for intraoperative neurophysiological monitoring in spine surgery: does it make a difference?

OBJECTIVE

The objective of this article was to undertake a systematic review of the literature to determine whether IOM is able to sensitively and specifically detect intraoperative neurologic injury during spine surgery and to assess whether IOM results in improved outcomes for patients during these procedures.

SUMMARY AND BACKGROUND DATA

Although relatively uncommon, perioperative neurologic injury, in particular spinal cord injury, is one of the most feared complications of spinal surgery. Intraoperative neuromonitoring (IOM) has been proposed as a method which could reduce perioperative neurologic complications after spine surgery.

METHODS

A systematic review of the English language literature was undertaken for articles published between 1990 and March 2009. MEDLINE, EMBASE, and Cochrane Collaborative Library databases were searched, as were the reference lists of published articles examining the use of IOM in spine surgery. Two independent reviewers assessed the level of evidence quality using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria, and disagreements were resolved by consensus.

RESULTS

A total of 103 articles were initially screened and 32 ultimately met the predetermined inclusion criteria. We determined that there is a high level of evidence that multimodal IOM is sensitive and specific for detecting intraoperative neurologic injury during spine surgery. There is a low level of evidence that IOM reduces the rate of new or worsened perioperative neurologic deficits. There is very low evidence that an intraoperative response to a neuromonitoring alert reduces the rate of perioperative neurologic deterioration.

CONCLUSION

Based on strong evidence that multimodality intraoperative neuromonitoring (MIOM) is sensitive and specific for detecting intraoperative neurologic injury during spine surgery, it is recommended that the use of MIOM be considered in spine surgery where the spinal cord or nerve roots are deemed to be at risk, including procedures involving deformity correction and procedures that require the placement of instrumentation. There is a need to develop evidence-based protocols to deal with intraoperative changes in MIOM and to validate these prospectively.

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.

Are induced pluripotent stem cells the future of cell-based regenerative therapies for spinal cord injury?

Despite advances in medical and surgical care, current clinical therapies for spinal cord injury (SCI) are limited. During the last two decades, the search for new therapies has been revolutionized by the discovery of stem cells, inspiring scientists and clinicians to search for stem cell-based reparative approaches for many disorders, including neurotrauma. Cell-based therapies using embryonic and adult stem cells in animal models of these disorders have provided positive outcome results. However, the availability of clinically suitable cell sources for human application has been hindered by both technical and ethical issues. The recent discovery of induced pluripotent stem (iPS) cells holds the potential to revolutionize the field of regenerative medicine by offering the option of autologous transplantation, thus eliminating the issue of host rejection. Herein, we will provide the rationale for the use of iPS cells in SCI therapies. In this review, we will evaluate the recent advancements in the field of iPS cells including their capacity for differentiation toward neural lineages that may allow iPS cells transplantation in cell-based therapy for spinal cord repair.

Membrane trauma and Na+ leak from Nav1.6 channels

During brain trauma, white matter experiences shear and stretch forces that, without severing axons, nevertheless trigger their secondary degeneration. In central nervous system (CNS) trauma models, voltage-gated sodium channel (Nav) blockers are neuroprotective. This, plus the rapid tetrodotoxin-sensitive Ca2+ overload of stretch-traumatized axons, points to "leaky" Nav channels as a pivotal early lesion in brain trauma. Direct effects of mechanical trauma on neuronal Nav channels have not, however, been tested. Here, we monitor immediate responses of recombinant neuronal Nav channels to stretch, using patch-clamp and Na+-dye approaches. Trauma constituted either bleb-inducing aspiration of cell-attached oocyte patches or abrupt uniaxial stretch of cells on an extensible substrate. Nav1.6 channel transient current displayed irreversible hyperpolarizing shifts of steady-state inactivation [availability(V)] and of activation [g(V)] and, thus, of window current. Left shift increased progressively with trauma intensity. For moderately intense patch trauma, a approximately 20-mV hyperpolarizing shift was registered. Nav1.6 voltage sensors evidently see lower energy barriers posttrauma, probably because of the different bilayer mechanics of blebbed versus intact membrane. Na+ dye-loaded human embryonic kidney (HEK) cells stably transfected with alphaNav1.6 were subjected to traumatic brain injury-like stretch. Cytoplasmic Na+ levels abruptly increased and the trauma-induced influx had a significant tetrodotoxin-sensitive component. Nav1.6 channel responses to cell and membrane trauma are therefore consistent with the hypothesis that mechanically induced Nav channel leak is a primary lesion in traumatic brain injury. Nav1.6 is the CNS node of Ranvier Nav isoform. When, during head trauma, nodes experienced bleb-inducing membrane damage of varying intensities, nodal Nav1.6 channels should immediately "leak" over a broadly left-smeared window current range.

Stimulating neuroregeneration as a therapeutic drug approach for traumatic brain injury

Traumatic brain injury, a silent epidemic of modern societies, is a largely neglected area in drug development and no drug is currently available for the treatment of patients suffering from brain trauma. Despite this grim situation, much progress has been made over the last two decades in closely related medical indications, such as spinal cord injury, giving rise to a more optimistic approach to drug development in brain trauma. Fundamental insights have been gained with animal models of central nervous system (CNS) trauma and spinal cord injury. Neuroregenerative drug candidates have been identified and two of these have progressed to clinical development for spinal cord injury patients. If successful, these drug candidates may be used to treat brain trauma patients. Significant progress has also been made in understanding the fundamental molecular mechanism underlying irreversible axonal growth arrest in the injured CNS of higher mammals. From these studies, we have learned that the axonal retraction bulb, previously regarded as a marker for failure of regenerative growth, is not static but dynamic and, therefore, amenable to pharmacotherapeutic approaches. With the development of modified magnetic resonance imaging methods, fibre tracts can be visualised in the living human brain and such imaging methods will soon be used to evaluate the neuroregenerative potential of drug candidates. These significant advances are expected to fundamentally change the often hopeless situation of brain trauma patients and will be the first step towards overcoming the silent epidemic of brain injury.

Towards personalized cell-replacement therapies for brain repair

The inability of the CNS to efficiently repair damage caused by trauma and neurodegenerative or demyelinating diseases has underlined the necessity for developing novel therapeutic strategies. Cell transplantation to replace lost neurons and the grafting of myelinating cells to repair demyelinating lesions are promising approaches for treating CNS injuries and demyelination. In this review, we will address the prospects of using stem cells or myelinating glial cells of the PNS, as well as olfactory ensheathing cells, in cell-replacement therapies. The recent generation of induced pluripotent stem cells from adult somatic cells by introduction of three or four genes controlling ‘stemness’ and their subsequent differentiation to desired phenotypes, constitutes a significant advancement towards personalized cell-replacement therapies.