Setting the stage for functional repair of spinal cord injuries: a cast of thousands

Comprehensive Therapeutic Approaches to Tuberculous Meningitis: Pharmacokinetics, Combined Dosing, and Advanced Intrathecal Therapies

Tuberculous meningitis (TBM) presents a critical neurologic emergency characterized by high mortality and morbidity rates, necessitating immediate therapeutic intervention, often ahead of definitive microbiological and molecular diagnoses. The primary hurdle in effective TBM treatment is the blood-brain barrier (BBB), which significantly restricts the delivery of anti-tuberculous medications to the central nervous system (CNS), leading to subtherapeutic drug levels and poor treatment outcomes. The standard regimen for initial TBM treatment frequently falls short, followed by adverse side effects, vasculitis, and hydrocephalus, driving the condition toward a refractory state. To overcome this obstacle, intrathecal (IT) sustained release of anti-TB medication emerges as a promising approach. This method enables a steady, uninterrupted, and prolonged release of medication directly into the cerebrospinal fluid (CSF), thus preventing systemic side effects by limiting drug exposure to the rest of the body. Our review diligently investigates the existing literature and treatment methodologies, aiming to highlight their shortcomings. As part of our enhanced strategy for sustained IT anti-TB delivery, we particularly seek to explore the utilization of nanoparticle-infused hydrogels containing isoniazid (INH) and rifampicin (RIF), alongside osmotic pump usage, as innovative treatments for TBM. This comprehensive review delineates an optimized framework for the management of TBM, including an integrated approach that combines pharmacokinetic insights, concomitant drug administration strategies, and the latest advancements in IT and intraventricular (IVT) therapy for CNS infections. By proposing a multifaceted treatment strategy, this analysis aims to enhance the clinical outcomes for TBM patients, highlighting the critical role of targeted drug delivery in overcoming the formidable challenges presented by the blood-brain barrier and the complex pathophysiology of TBM.

The GLP-1 receptor agonist exenatide improves recovery from spinal cord injury by inducing macrophage polarization toward the M2 phenotype

Although a wide variety of mechanisms take part in the secondary injury phase of spinal cord injury (SCI), inflammation is the most important factor implicated in the sequelae after SCI. Being central to the inflammation reaction, macrophages and their polarization are a topic that has garnered wide interest in the studies of SCI secondary injury. The glucagon-like peptide 1 (GLP-1) receptor agonist exenatide has been shown to enhance the endoplasmic reticulum stress response and improve motor function recovery after spinal cord injury (SCI). Since exenatide has also been reported to induce the production of M2 cells in models of cerebral infarction and neurodegenerative diseases, this study was conducted to examine the effects of exenatide administration on the inflammation process that ensues after spinal cord injury. In a rat contusion model of spinal cord injury, the exenatide group received a subcutaneous injection of 10 μg exenatide immediately after injury while those in the control group received 1 mL of phosphate-buffered saline. Quantitative RT-PCR and immunohistochemical staining were used to evaluate the effects of exenatide administration on the macrophages infiltrating the injured spinal cord, especially with regard to macrophage M1 and M2 profiles. The changes in hind limb motor function were assessed based on Basso, Beattie, Bresnahan locomotor rating scale (BBB scale) scores. The improvement in BBB scale scores was significantly higher in the exenatide group from day 7 after injury and onwards. Quantitative RT-PCR revealed an increase in the expression of M2 markers and anti-inflammatory interleukins in the exenatide group that was accompanied by a decrease in the expression of M1 markers and inflammatory cytokines. Immunohistochemical staining showed no significant difference in M1 macrophage numbers between the two groups, but a significantly higher number of M2 macrophages was observed in the exenatide group on day 3 after injury. Our findings suggest that exenatide administration promoted the number of M2-phenotype macrophages after SCI, which may have led to the observed improvement in hind limb motor function in a rat model of SCI.

Understanding exosomes: Part 2-Emerging leaders in regenerative medicine

Exosomes are the smallest subset of extracellular signaling vesicles secreted by most cells with the ability to communicate with other tissues and cell types over long distances. Their use in regenerative medicine has gained tremendous momentum recently due to their ability to be utilized as therapeutic options for a wide array of diseases/conditions. Over 5000 publications are currently being published yearly on this topic, and this number is only expected to dramatically increase as novel therapeutic strategies continue to be developed. Today exosomes have been applied in numerous contexts including neurodegenerative disorders (Alzheimer's disease, central nervous system, depression, multiple sclerosis, Parkinson's disease, post-traumatic stress disorders, traumatic brain injury, peripheral nerve injury), damaged organs (heart, kidney, liver, stroke, myocardial infarctions, myocardial infarctions, ovaries), degenerative processes (atherosclerosis, diabetes, hematology disorders, musculoskeletal degeneration, osteoradionecrosis, respiratory disease), infectious diseases (COVID-19, hepatitis), regenerative procedures (antiaging, bone regeneration, cartilage/joint regeneration, osteoarthritis, cutaneous wounds, dental regeneration, dermatology/skin regeneration, erectile dysfunction, hair regrowth, intervertebral disc repair, spinal cord injury, vascular regeneration), and cancer therapy (breast, colorectal, gastric cancer and osteosarcomas), immune function (allergy, autoimmune disorders, immune regulation, inflammatory diseases, lupus, rheumatoid arthritis). This scoping review is a first of its kind aimed at summarizing the extensive regenerative potential of exosomes over a broad range of diseases and disorders.

Involvement of microglia in chronic neuropathic pain associated with spinal cord injury - a systematic review

In recent decade microglia have been found to have a central role in the development of chronic neuropathic pain after injury to the peripheral nervous system. It is widely accepted that peripheral nerve injury triggers microglial activation in the spinal cord, which contributes to heightened pain sensation and eventually chronic pain states. The contribution of microglia to chronic pain arising after injury to the central nervous system, such as spinal cord injury (SCI), has been less studied, but there is evidence supporting microglial contribution to central neuropathic pain. In this systematic review, we focused on post-SCI microglial activation and how it is linked to emergence and maintenance of chronic neuropathic pain arising after SCI. We found that the number of studies using animal SCI models addressing microglial activity is still small, compared with the ones using peripheral nerve injury models. We have collected 20 studies for full inclusion in this review. Many mechanisms and cellular interactions are yet to be fully understood, although several studies report an increase of density and activity of microglia in the spinal cord, both in the vicinity of the injury and in the spared spinal tissue, as well as in the brain. Changes in microglial activity come with several molecular changes, including expression of receptors and activation of signalling pathways. As with peripheral neuropathic pain, microglia seem to be important players and might become a therapeutic target in the future.

Molecular Mechanism Operating in Animal Models of Neurogenic Detrusor Overactivity: A Systematic Review Focusing on Bladder Dysfunction of Neurogenic Origin

Neurogenic detrusor overactivity (NDO) is a severe lower urinary tract disorder, characterized by urinary urgency, retention, and incontinence, as a result of a neurologic lesion that results in damage in neuronal pathways controlling micturition. The purpose of this review is to provide a comprehensive framework of the currently used animal models for the investigation of this disorder, focusing on the molecular mechanisms of NDO. An electronic search was performed with PubMed and Scopus for literature describing animal models of NDO used in the last 10 years. The search retrieved 648 articles, of which reviews and non-original articles were excluded. After careful selection, 51 studies were included for analysis. Spinal cord injury (SCI) was the most frequently used model to study NDO, followed by animal models of neurodegenerative disorders, meningomyelocele, and stroke. Rats were the most commonly used animal, particularly females. Most studies evaluated bladder function through urodynamic methods, with awake cystometry being particularly preferred. Several molecular mechanisms have been identified, including changes in inflammatory processes, regulation of cell survival, and neuronal receptors. In the NDO bladder, inflammatory markers, apoptosis-related factors, and ischemia- and fibrosis-related molecules were found to be upregulated. Purinergic, cholinergic, and adrenergic receptors were downregulated, as most neuronal markers. In neuronal tissue, neurotrophic factors, apoptosis-related factors, and ischemia-associated molecules are increased, as well as markers of microglial and astrocytes at lesion sites. Animal models of NDO have been crucial for understanding the pathophysiology of lower urinary tract (LUT) dysfunction. Despite the heterogeneity of animal models for NDO onset, most studies rely on traumatic SCI models rather than other NDO-driven pathologies, which may result in some issues when translating pre-clinical observations to clinical settings other than SCI.

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

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

Fighting for recovery on multiple fronts: The past, present, and future of clinical trials for spinal cord injury

Through many decades of preclinical research, great progress has been achieved in understanding the complex nature of spinal cord injury (SCI). Preclinical research efforts have guided and shaped clinical trials, which are growing in number by the year. Currently, 1,149 clinical trials focused on improving outcomes after SCI are registered in the U.S. National Library of Medicine at ClinicalTrials.gov. We conducted a systematic analysis of these SCI clinical trials, using publicly accessible data downloaded from ClinicalTrials.gov. After extracting all available data for these trials, we categorized each trial according to the types of interventions being tested and the types of outcomes assessed. We then evaluated clinical trial characteristics, both globally and by year, in order to understand the areas of growth and change over time. With regard to clinical trial attributes, we found that most trials have low enrollment, only test single interventions, and have limited numbers of primary outcomes. Some gaps in reporting are apparent; for instance, over 75% of clinical trials with "Completed" status do not have results posted, and the Phase of some trials is incorrectly classified as "Not applicable" despite testing a drug or biological compound. When analyzing trials based on types of interventions assessed, we identified the largest representation in trials testing rehab/training/exercise, neuromodulation, and behavioral modifications. Most highly represented primary outcomes include motor function of the upper and lower extremities, safety, and pain. The most highly represented secondary outcomes include quality of life and pain. Over the past 15 years, we identified increased representation of neuromodulation and rehabilitation trials, and decreased representation of drug trials. Overall, the number of new clinical trials initiated each year continues to grow, signifying a hopeful future for the clinical treatment of SCI. Together, our work provides a comprehensive glimpse into the past, present, and future of SCI clinical trials, and suggests areas for improvement in clinical trial reporting.

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

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

Mesenchymal Stem Cells in Treatment of Spinal Cord Injury and Amyotrophic Lateral Sclerosis

Preclinical and clinical studies with various stem cells, their secretomes, and extracellular vesicles (EVs) indicate their use as a promising strategy for the treatment of various diseases and tissue defects, including neurodegenerative diseases such as spinal cord injury (SCI) and amyotrophic lateral sclerosis (ALS). Autologous and allogenic mesenchymal stem cells (MSCs) are so far the best candidates for use in regenerative medicine. Here we review the effects of the implantation of MSCs (progenitors of mesodermal origin) in animal models of SCI and ALS and in clinical studies. MSCs possess multilineage differentiation potential and are easily expandable in vitro. These cells, obtained from bone marrow (BM), adipose tissue, Wharton jelly, or even other tissues, have immunomodulatory and paracrine potential, releasing a number of cytokines and factors which inhibit the proliferation of T cells, B cells, and natural killer cells and modify dendritic cell activity. They are hypoimmunogenic, migrate toward lesion sites, induce better regeneration, preserve perineuronal nets, and stimulate neural plasticity. There is a wide use of MSC systemic application or MSCs seeded on scaffolds and tissue bridges made from various synthetic and natural biomaterials, including human decellularized extracellular matrix (ECM) or nanofibers. The positive effects of MSC implantation have been recorded in animals with SCI lesions and ALS. Moreover, promising effects of autologous as well as allogenic MSCs for the treatment of SCI and ALS were demonstrated in recent clinical studies.

Cervical Spinal Cord Transcutaneous Stimulation Improves Upper Extremity and Hand Function in People With Complete Tetraplegia: A Case Study

Recovery of the upper extremity (UE) and hand function is considered the highest priority for people with tetraplegia, because these functions closely integrate with their activities of daily living. Spinal cord transcutaneous stimulation (scTS) has great potential to facilitate functional restoration of paralyzed limbs by neuro-modulating the excitability of the spinal network. Recently, this approach has been demonstrated effective in improving UE function in people with motor complete and incomplete cervical SCI. However, the research thus far is limited by the lack of a comprehensive assessment of functional improvement and neurological recovery throughout the intervention. The goal of this study was to investigate whether scTS can also facilitate UE functional restoration in an individual with motor and sensory complete tetraplegia. A 38-year-old male with a C5 level, ASIA Impairment Scale-A SCI (15 years post-injury, left hand dominant pre- and post-injury), received 18 sessions (60 minutes/session) of scTS combined with task-specific hand training over the course of 8 weeks. The total score of the Graded Redefined Assessment of Strength, Sensibility, and Prehension significantly improved from 72/232 to 96/232 at post-intervention, and maintained ranging from 82/232 to 86/232 during the three months follow-up without any further treatment. The bilateral handgrip force improved by 283.4% (left) and 30.7% (right), respectively at post-intervention. These strength gains were sustained at 233.5% -250% (left) and 11.5%-73.1% (right) during the follow-up evaluation visits. Neuromuscular Recovery Scale demonstrated dramatic and long-lasting improvements following the completion of the intervention. Changes of spinal motor evoked potentials from pre- to post-intervention indicated an increased level of spinal network excitability. The present data offer preliminary evidence that the novel scTS intervention combined with hand training can enhance UE functional use in people with motor and sensory complete SCI.

Up-regulation of MicroRNAs-21 and -223 in a Sprague-Dawley Rat Model of Traumatic Spinal Cord Injury

In this experimental animal study, we examined alterations in the degree of transcription of two microRNAs (miRs)—miR-21 and -223—in a Sprague-Dawley (SD) rat model of traumatic spinal cord injury (TSCI). Depending on the volume of the balloon catheter (V), a total of 75 male SD rats were divided into the three experimental groups: the sham group (n = 25; V = 0 μL), the mild group (n = 25; V = 20 μL), and the severe group (n = 25; V = 50 μL). Successful induction of TSCI was confirmed on both locomotor rating scale at 4 h and 1, 3 and 7 days post-lesion and histopathologic examinations. Then, RNA isolation and quantitative polymerase chain reaction (PCR) were performed. No differences in the level of miR-21 expression were found at the first time point studied (4 h post-lesion) between the three experimental groups, whereas such differences were significant at all the other time points (p < 0.05). Moreover, there were significant alterations in the level of miR-223 expression at all time points studied through all the experimental groups (p < 0.05). Furthermore, locomotor rating scale scores had a linear relationship with the level of miR-21 expression (R² = 0.4363, Y = 1.661X + 3.096) and that of miR-223 one (R² = 0.9104, Y = 0.8385X + 2.328). Taken together, we conclude that up-regulation of miR-21 and -223 might be closely associated with progression and the early course of TSCI, respectively.

ChABC-loaded PLGA nanoparticles: A comprehensive study on biocompatibility, functional recovery, and axonal regeneration in animal model of spinal cord injury

Spinal Cord Injury (SCI) is one of the leading causes of physical disability. In this study, spherical PLGA nanoparticles (NPs) containing ChABC enzyme were manufactured and fully characterized for SCI therapy. The NPs were used in the rat's contused spinal cord to assess the functional improvement and scar digestion. Twenty-three adult male Wistar rats (275 ± 25 g) were assigned into four groups of control, sham, blank-treated particle, and ChABC-treated particle. Throughout the survey, the BBB scores were obtained for all the groups. Finally, the injured sections of animals were dissected, and histological studies were conducted using Luxol fast blue and Bielschowsky. The biocompatibility and non-toxicity effects of the NPs on olfactory ensheathing cells (OECs) were confirmed by the MTT test. The flow-cytometry revealed the purity of cultured OECs with p75⁺/GFAP⁺ at around 87.9 ± 2.4%. Animals in the control and the blank-treated groups exhibited significantly lower BBB scores compared with the ChABC-treated particle group. Histological results confirmed the induced contusion models in the injured site. Myelin was observed in the treated groups, especially when the ChABC-loaded nanoparticles were utilized. The immunohistochemistry results indicated the scar glial degradation in animals treated by the ChABC-loaded particles. According to this study, the loaded particles can potentially serve as a suitable candidate for spinal cord repair, functional recovery and axonal regeneration.

A Narrative Review of Pediatric Nontraumatic Spinal Cord Dysfunction

This article provides a narrative review of seven key issues relevant to pediatric onset of spinal cord damage not due to trauma, or spinal cord dysfunction (SCDys). The first topic discussed is terminology issues. There is no internationally accepted term for spinal cord damage not due to trauma. The implications of this terminology issue and an approach to addressing this are discussed. Second, a brief history of SCDys is presented, focusing on conditions relevant to pediatrics. Third, the classification of SCDys is outlined, based on the International Spinal Cord Injury Data Sets for Non-Traumatic Spinal Cord Injury. Following this, a summary is given of the epidemiology of pediatric SCDys, primarily focused on the incidence, prevalence, and etiology, with a comparison to traumatic spinal cord injury. Next, important clinical rehabilitation principles unique to children with SCDys are highlighted. Then important prevention opportunities for SCDys in children are discussed. Finally, trends, challenges, and opportunities regarding research in SCDys are mentioned.

Anatomic conditions for bypass surgery between rostral (T7-T9) and caudal (L2, L4, S1) ventral roots to treat paralysis after spinal cord injury

Severe spinal cord injuries cause permanent neurological deficits and are still considered as inaccessible to efficient therapy. Injured spinal cord axons are unable to spontaneously regenerate. Re-establishing functional activity especially in the lower limbs by reinnervation of the caudal infra-lesional territories might represent an effective therapeutic strategy. Numerous surgical neurotizations have been developed to bridge the spinal cord lesion site and connect the intact supra-lesional portions of the spinal cord to peripheral nerves (spinal nerves, intercostal nerves) and muscles. The major disadvantage of these techniques is the increased hypersensitivity, spasticity and pathologic pain in the spinal cord injured patients, which occur due to the vigorous sprouting of injured afferent sensory fibers after reconstructive surgery. Using micro-surgical instruments and an operation microscope we performed detailed anatomical preparation of the vertebral canal and its content in five human cadavers. Our observations allow us to put forward the possibility to develop a more precise surgical approach, the so called "ventral root bypass" that avoids lesion of the dorsal roots and eliminates sensitivity complications. The proposed kind of neurotization has been neither used, nor put forward. The general opinion is that radix ventralis and radix dorsalis unite to form the spinal nerve inside the dural sac. This assumption is not accurate, because both radices leave the dural sac separately. This neglected anatomical feature allows a reliable intravertebral exposure of the dura-mater ensheathed ventral roots and their damage-preventing end-to-side neurorrhaphy by interpositional nerve grafts.

Trends, Challenges, and Opportunities Regarding Research in Non-traumatic Spinal Cord Dysfunction

Background: Spinal cord dysfunction (SCDys) is caused by heterogeneous health conditions, and the incidence is increasing. Despite the growing interest in rehabilitation research for SCDys, research into SCDys faces many challenges. Objective: The objective of this project was to perform a clinical review of changes in SCDys research over the last 4 decades; identify challenges to conducting research in SCDys; and propose opportunities for improving research in SCDys. Methods: A triangulation approach was used for obtaining evidence: literature search (January 2017) using MEDLINE and Embase databases for publications in English (1974-2016) regarding SCDys; workshop discussions at the International Spinal Cord Society annual meeting, September 16, 2016, Vienna, Austria; and our collective expertise in SCDys clinical rehabilitation research. Results: There has been a substantial increase in publications on SCDys over the 4 decades, from 1,825 in 1974-1983 to 11,887 in the decade 2004-2013, along with an improvement in research methodology. Numerous challenges to research in SCDys rehabilitation were grouped into the following themes: (a) identification of cases; (b) study design and data collection; and (c) funding, preclinical, and international research. Opportunities for addressing these were identified. Conclusions: The increase in scientific publications on SCDys highlights the importance of this heterogeneous group among the research community. The overall lack of good quality epidemiological studies regarding incidence, prevalence, and survival in these patients serves as a benchmark for guiding improvements to inform evidence-based care and policy.

Improved grasp function with transcranial direct current stimulation in chronic spinal cord injury

BACKGROUND

Recovering hand function has important implications for improving independence of patients with tetraplegia after traumatic spinal cord injury (SCI). Transcranial direct current stimulation (tDCS) is a noninvasive neuromodulation technique that has potential to improve motor function.

OBJECTIVE

To investigate the effects of one session of 1 mA, 2 mA, and sham anodal tDCS (a-tDCS) in the upper extremity (hand) motor performance (grasp and lease) in patients with chronic cervical SCI.

METHODS

Eleven participants with incomplete SCI were randomized to receive 20 minutes of 1 mA, 2 mA, or sham stimulation over the targeted motor cortex over three separated sessions. Hand motor performance was measured by a hand robotic evaluation (kinematics) and the Box and Blocks (BB) test before and after the stimulation period.

RESULTS

A significant improvement on the grasp mean to peak speed ratio (GMP) was observed in the 2 mA group (pre: 0.38±0.02; post: 0.43±0.03; mean±SEM; p = 0.031). There was no statistically significant difference in BB test results, however the 2 mA intervention showed a positive trend for improvement.

CONCLUSIONS

A single session of 2 mA of a-tDCS showed gains in hand motor function in patients with chronic SCI that were not observed in functional clinical scales. The use of robotic kinematics showed promising results in assessing small changes in motor performance. Further studies are necessary to determine whether tDCS can be an effective long-term rehabilitation strategy for individuals with SCI.

Amiloride Promotes Oligodendrocyte Survival and Remyelination after Spinal Cord Injury in Rats

After spinal cord injury (SCI), secondary injury results in an expanding area of glial cell apoptosis. Oligodendrocyte precursor cells (OPCs) actively proliferate after SCI, but many of these cells undergo apoptosis. One of the factors that exacerbates secondary injury is endoplasmic reticulum (ER) stress. In this study, we tested the effects of amiloride treatment on the fate of OPCs during secondary injury in rats. Amiloride is an FDA-approved diuretic for treating hypertension, which in rats enhances ER stress response and suppresses the apoptosis of glial cells after SCI. A severe contusive SCI was induced in Sprague-Dawley rats using an infinite horizon (IH)-impactor (200 kdyne). Beginning 24 h after SCI, 10 mg/kg of amiloride or phosphate buffered saline (PBS) was intraperitoneally administered daily for a period of 14 days. At 7, 14, 28, and 56 days after SCI, animals were subsequently euthanized in order to analyze the injured spinal cord. We labeled proliferating OPCs and demonstrated that amiloride treatment led to greater numbers of OPCs and oligodendrocytes in the injured spinal cord. Increased myelin basic protein (MBP) expression levels were observed, suggesting that increased numbers of mature oligodendrocytes led to improved remyelination, significantly improving motor function recovery.

Immunoproteomic identification of antigenic candidate Campylobacter jejuni and human peripheral nerve proteins involved in Guillain-Barré syndrome

Immunoproteomics is become a potent methodology used for identifying immunoreactive proteins. In this study, an immunoproteomic approach based on 2-dimensional gel electrophoresis (2D-PAGE) and immunoblotting combined with high resolution mass spectrometry (MS) was used to identify immunoreactive proteins that might be involved in mechanisms of Guillain-Barré syndrome (GBS) development, regardless of their potential reciprocal molecular mimicry. Proteins isolated from C. jejuni and human peripheral nerve tissue (HPN) were separated with 2D SDS-PAGE and subjected to western blotting using serum samples from GBS patients. The peptides generated after proteolysis of the immunoreactive proteins were submitted to nanoflow-high performance liquid chromatography-nano electrospray ionization coupled to high resolution mass spectrometry (nHPLC-nESI-MS and MS/MS) followed by SEQUESTdata analysis for proteins identification. In C. jejuni, immunoreactivity was found for GroEL and DnaK, structural proteins (MOMP), key enzymatic proteins necessary for the microbial proliferation (adenylate kinase, enolase, inorganic pyrophosphatase and aspartate ammonia-lyase), and antioxidant enzymes (alkyl hydroperoxide reductase-AhpC and DNA protection during starvation protein - DNA protection factor against Fe²⁺-mediated oxidative stress). HPN immunoreactive proteins identified were heat shock proteins (HSP), intermediate filaments (vimentin and desmin), and other proteins and enzymes such as troponin/tropomyosin complex and ATP synthase subunit beta and the keratan sulfate proteoglycan lumican. The targeting of vimentin and desmin, suggested that the neuronal autoimmune damage is specifically directed to intermediate neuronal (vimentin) and neuromuscular IF, probably localized nearby cell surface, affording increased accessibility to autoantibodies. These findings suggest that the post-infectious development of GBS may be also associated to additional concomitant immune factors that lead to nerve damage generated by auto-immune trigger(s) different from molecular mimicry.

A comparative transcriptomic analysis of astrocytes differentiation from human neural progenitor cells

Astrocytes are a morphologically and functionally heterogeneous population of cells that play critical roles in neurodevelopment and in the regulation of central nervous system homeostasis. Studies of human astrocytes have been hampered by the lack of specific molecular markers and by the difficulties associated with purifying and culturing astrocytes from adult human brains. Human neural progenitor cells (NPCs) with self-renewal and multipotent properties represent an appealing model system to gain insight into the developmental genetics and function of human astrocytes, but a comprehensive molecular characterization that confirms the validity of this cellular system is still missing. Here we used an unbiased transcriptomic analysis to characterize in vitro culture of human NPCs and to define the gene expression programs activated during the differentiation of these cells into astrocytes using FBS or the combination of CNTF and BMP4. Our results demonstrate that in vitro cultures of human NPCs isolated during the gliogenic phase of neurodevelopment mainly consist of radial glial cells (RGCs) and glia-restricted progenitor cells. In these cells the combination of CNTF and BMP4 activates the JAK/STAT and SMAD signaling cascades, leading to the inhibition of oligodendrocytes lineage commitment and activation of astrocytes differentiation. On the other hand, FBS-derived astrocytes have properties of reactive astrocytes. Our work suggests that in vitro culture of human NPCs represents a valuable cellular system to study human disorders characterized by impairment of astrocytes development and function. Our datasets represent an important resource for researchers studying human astrocytes development and might set the basis for the discovery of novel human-specific astrocyte markers.

An In Situ Gelling Drug Delivery System for Improved Recovery after Spinal Cord Injury

Therapeutic strategies for the spinal cord injury (SCI) are limited by the current available drug delivery techniques. Here, an in situ gelling drug delivery system (DDS), composed of a Poloxamer-407, a 188 mixture-based thermoresponsive hydrogel matrix and, an incorporated therapeutic compound (monosialoganglioside, GM1), is developed for SCI therapy. A low-thoracic hemisection in rats is used as SCI model to evaluate therapeutic efficiency. The GM1-incorporating Poloxamer-407 and 188 polymer solution is converted to a hydrogel (GM1-hydrogel) upon instillation to the injured spinal cord, due to the increased temperature. At body temperature, the thermoresponsive hydrogel prolongs the release of GM1 for about 1 month, due to the superposition of dissolution and swelling (anomalous transport) of the hydrogel matrix. The sustained release of the GM1-hydrogel enables the prolonged residence time of GM1 at the injured spinal cord, decreases the frequency of administration and, consequently, may improve patient compliance. After SCI, the administration of GM1-hydrogel to the lesion site inhibits the apoptotic cell death and glial scar formation, enhances the neuron regeneration, provides neuroprotection to the injured spinal cord, and improves the locomotor recovery. Overall, this study opens future perspectives for the treatment of SCI with a prolonged drug release DDS.

Induced Pluripotent Stem Cell Therapies for Cervical Spinal Cord Injury

Cervical-level injuries account for the majority of presented spinal cord injuries (SCIs) to date. Despite the increase in survival rates due to emergency medicine improvements, overall quality of life remains poor, with patients facing variable deficits in respiratory and motor function. Therapies aiming to ameliorate symptoms and restore function, even partially, are urgently needed. Current therapeutic avenues in SCI seek to increase regenerative capacities through trophic and immunomodulatory factors, provide scaffolding to bridge the lesion site and promote regeneration of native axons, and to replace SCI-lost neurons and glia via intraspinal transplantation. Induced pluripotent stem cells (iPSCs) are a clinically viable means to accomplish this; they have no major ethical barriers, sources can be patient-matched and collected using non-invasive methods. In addition, the patient’s own cells can be used to establish a starter population capable of producing multiple cell types. To date, there is only a limited pool of research examining iPSC-derived transplants in SCI—even less research that is specific to cervical injury. The purpose of the review herein is to explore both preclinical and clinical recent advances in iPSC therapies with a detailed focus on cervical spinal cord injury.

Nanoparticle-Hydrogel: A Hybrid Biomaterial System for Localized Drug Delivery

Nanoparticles have offered a unique set of properties for drug delivery including high drug loading capacity, combinatorial delivery, controlled and sustained drug release, prolonged stability and lifetime, and targeted delivery. To further enhance therapeutic index, especially for localized application, nanoparticles have been increasingly combined with hydrogels to form a hybrid biomaterial system for controlled drug delivery. Herein, we review recent progresses in engineering such nanoparticle-hydrogel hybrid system (namely 'NP-gel') with a particular focus on its application for localized drug delivery. Specifically, we highlight four research areas where NP-gel has shown great promises, including (1) passively controlled drug release, (2) stimuli-responsive drug delivery, (3) site-specific drug delivery, and (4) detoxification. Overall, integrating therapeutic nanoparticles with hydrogel technologies creates a unique and robust hybrid biomaterial system that enables effective localized drug delivery.

The efficacy of neuromuscular electrical stimulation with alternating currents in the kilohertz frequency to stimulate gait rhythm in rats following spinal cord injury

Background

Rehabilitation facilitates the reorganization of residual/regenerated neural pathways and is key in improving motor function following spinal cord injury. Neuromuscular electrical stimulation (NMES) has been reported as being clinically effective. Although it can be used after the acute phase post-injury, the optimal stimulation conditions to improve motor function remain unclear. In this paper, we examined the effectiveness of NMES with alternating currents in the kilohertz (kHz) frequency in gait rhythm stimulation therapy.

Methods

Tests were performed using 20 mature female Fischer rats. Incomplete spinal cord injuries (T9 level) were made with an IH impactor using a force of 150 kdyn, and NMES was administered for 3 days from the 7th day post-injury. The needle electrodes were inserted percutaneously near the motor point of each muscle in conscious rats, and each muscle on the left and right leg was stimulated for 15 min at two frequencies, 75 Hz and 8 kHz, to induce a gait rhythm. Motor function was evaluated using Basso, Beattie, Bresnahan (BBB) scores and three-dimensional (3D) gait analysis. Rats were divided into four groups (5 rats/group), including the NMES treatment 75-Hz group (iSCI-NMES 75 Hz), 8-kHz group (iSCI-NMES 8 kHz), injury control group (iSCI-NT), and normal group (Normal-CT), and were compared.

Results

There was no significant difference in BBB scores among the three groups. In 3D gait analysis, compared with the injury control group, the 8-kHz group showed a significant improvement in synergistic movement of both hindlimbs.

Conclusion

We suggest that kHz stimulation is effective in gait rhythm stimulation using NMES.

Bridging the lesion-engineering a permissive substrate for nerve regeneration

Biomaterial-based strategies to restore connectivity after lesion at the spinal cord are focused on bridging the lesion and providing an favourable substrate and a path for axonal re-growth. Following spinal cord injury (SCI) a hostile environment for neuronal cell growth is established by the activation of multiple inhibitory mechanisms that hamper regeneration to occur. Implantable scaffolds can provide mechanical support and physical guidance for axon re-growth and, at the same time, contribute to alleviate the hostile environment by the in situ delivery of therapeutic molecules and/or relevant cells. Basic research on SCI has been contributing with the description of inhibitory mechanisms for regeneration as well as identifying drugs/molecules that can target inhibition. This knowledge is the background for the development of combined strategies with biomaterials. Additionally, scaffold design is significantly evolving. From the early simple hollow conduits, scaffolds with complex architectures that can modulate cell fate are currently being tested. A number of promising pre-clinical studies combining scaffolds, cells, drugs and/or nucleic acids are reported in the open literature. Overall, it is considered that to address the multi-factorial inhibitory environment of a SCI, a multifaceted therapeutic approach is imperative. The progress in the identification of molecules that target inhibition after SCI and its combination with scaffolds and/or cells are described and discussed in this review.

Biomarkers of spinal cord injury and ensuing bladder dysfunction

During the acute phase of SCI, the extension and residual neurological deficits that will persist after the waning of the spinal shock period are difficult to estimate on clinical grounds. Therefore, objective biomarkers able to estimate the extension of the lesion and the degree of neurological recovery are of great importance. Research has been focused on the detection of structural neuronal and glial proteins that leak from damaged cells, inflammatory proteins recruited to remove necrotic debris and more accurate neuroimaging methods that are able to discriminate the extension and functional consequences of the SCI. Urinary biomarkers are also being investigated to estimate functional changes that typically affect bladder function following SCI which can endanger patient's life in the long run. Future studies are needed to precisely characterize the composition and function of the glial scar that appears in the area of SCI and repeals axonal growth, therefore preventing axonal rewiring.

Transplantation of Cerebral Dopamine Neurotrophic Factor Transducted BMSCs in Contusion Spinal Cord Injury of Rats: Promotion of Nerve Regeneration by Alleviating Neuroinflammation

Traumatic spinal cord injury (SCI) causes neuron death and axonal damage resulting in functional motor and sensory loss, showing limited regeneration because of adverse microenvironment such as neuroinflammation and glial scarring. Currently, there is no effective therapy to treat SCI in clinical practice. Bone marrow-derived mesenchymal stem cells (BMSCs) are candidates for cell therapies but its effect is limited by neuroinflammation and adverse microenvironment in the injured spinal cord. In this study, we developed transgenic BMSCs overexpressing cerebral dopamine neurotrophic factor (CDNF), a secretory neurotrophic factor that showed potent effects on neuron protection, anti-inflammation, and sciatic nerve regeneration in previous studies. Our results showed that the transplantation of CDNF-BMSCs suppressed neuroinflammation and decreased the production of proinflammatory cytokines after SCI, resulting in the promotion of locomotor function and nerve regeneration of the injured spinal cord. This study presents a novel promising strategy for the treatment of spinal cord injury.

Function of microglia and macrophages in secondary damage after spinal cord injury

Spinal cord injury (SCI) is a devastating type of neurological trauma with limited therapeutic opportunities. The pathophysiology of SCI involves primary and secondary mechanisms of injury. Among all the secondary injury mechanisms, the inflammatory response is the major contributor and results in expansion of the lesion and further loss of neurologic function. Meanwhile, the inflammation directly and indirectly dominates the outcomes of SCI, including not only pain and motor dysfunction, but also preventingneuronal regeneration. Microglia and macrophages play very important roles in secondary injury. Microglia reside in spinal parenchyma and survey the microenvironment through the signals of injury or infection. Macrophages are derived from monocytes recruited to injured sites from the peripheral circulation. Activated resident microglia and monocyte-derived macrophages induce and magnify immune and inflammatory responses not only by means of their secretory moleculesand phagocytosis, but also through their influence on astrocytes, oligodendrocytes and demyelination. In this review, we focus on the roles of microglia and macrophages in secondary injury and how they contribute to the sequelae of SCI.

Olfactory ensheathing cell transplantation for spinal cord injury: An 18-year bibliometric analysis based on the Web of Science

OBJECTIVE

Olfactory ensheathing cell (OEC) transplantation is a promising new approach for the treatment of spinal cord injury (SCI), and an increasing number of scientific publications are devoted to this treatment strategy. This bibliometric analysis was conducted to assess global research trends in OEC transplantation for SCI.

DATA SOURCE

All of the data in this study originate from the Web of Science maintained by the Institute for Scientific Information, USA, and includes SCI-EXPANDED, SSCI, A&HCI, CPCI-S, CPCI-SSH, BKCI-S, BKCI-SSH, CCR-EXPANDED and IC. The Institute for Scientific Information's Web of Science was searched using the keywords "olfactory ensheathing cells" or "OECs" or "olfactory ensheathing glia" or "OEG" or "olfactory ensheathing glial cells" or "OEGs" and "spinal cord injury" or "SCI" or "spinal injury" or "spinal transection" for literature published from January 1898 to May 2012.

DATA SELECTION

Original articles, reviews, proceedings papers and meeting abstracts, book chapters and editorial materials on OEC transplantation for SCI were included. Simultaneously, unpublished literature and literature for which manual information retrieval was required were excluded.

MAIN OUTCOME MEASURES

ALL SELECTED LITERATURES ADDRESSING OEC TRANSPLANTATION FOR SCI WERE EVALUATED IN THE FOLLOWING ASPECTS: publication year, document type, language, author, institution, times cited, Web of Science category, core source title, countries/territories and funding agency.

RESULTS

In the Web of Science published by the Institute for Scientific Information, the earliest literature record was in April, 1995. Four hundred and fourteen publications addressing OEC transplantation for SCI were added to the data library in the past 18 years, with an annually increasing trend. Of 415 records, 405 publications were in English. Two hundred and fifty-nine articles ranked first in the distribution of document type, followed by 141 reviews. Thirty articles and 20 reviews, cited more than 55 times by the date the publication data were downloaded by us, can be regarded as the most classical references. The journal Experimental Neurology published the most literature (32 records), followed by Glia. The United States had the most literature, followed by China. In addition, Yale University was the most productive institution in the world, while The Second Military Medical University contributed the most in China. The journal Experimental Neurology published the most OEC transplantation literature in the United States, while Neural Regeneration Research published the most in China.

CONCLUSION

This analysis provides insight into the current state and trends in OEC transplantation for SCI research. Furthermore, we anticipate that this analysis will help encourage international cooperation and teamwork on OEC transplantation for SCI to facilitate the development of more effective treatments for SCI.

Extracellular matrix regulation of inflammation in the healthy and injured spinal cord

Throughout the body, the extracellular matrix (ECM) provides structure and organization to tissues and also helps regulate cell migration and intercellular communication. In the injured spinal cord (or brain), changes in the composition and structure of the ECM undoubtedly contribute to regeneration failure. Less appreciated is how the native and injured ECM influences intraspinal inflammation and, conversely, how neuroinflammation affects the synthesis and deposition of ECM after CNS injury. In all tissues, inflammation can be initiated and propagated by ECM disruption. Molecules of ECM newly liberated by injury or inflammation include hyaluronan fragments, tenascins, and sulfated proteoglycans. These act as "damage-associated molecular patterns" or "alarmins", i.e., endogenous proteins that trigger and subsequently amplify inflammation. Activated inflammatory cells, in turn, further damage the ECM by releasing degradative enzymes including matrix metalloproteinases (MMPs). After spinal cord injury (SCI), destabilization or alteration of the structural and chemical compositions of the ECM affects migration, communication, and survival of all cells - neural and non-neural - that are critical for spinal cord repair. By stabilizing ECM structure or modifying their ability to trigger the degradative effects of inflammation, it may be possible to create an environment that is more conducive to tissue repair and axon plasticity after SCI.

Microglia response and in vivo therapeutic potential of methylprednisolone-loaded dendrimer nanoparticles in spinal cord injury

The control and manipulation of cells that trigger secondary mechanisms following spinal cord injury (SCI) is one of the first opportunities to minimize its highly detrimental outcomes. Herein, the ability of surface-engineered carboxymethylchitosan/polyamidoamine (CMCht/PAMAM) dendrimer nanoparticles to intracellularly deliver methylprednisolone (MP) to glial cells, allowing a controlled and sustained release of this corticosteroid in the injury site, is investigated. The negatively charged MP-loaded CMCht/PAMAM dendrimer nanoparticles with sizes of 109 nm enable a MP sustained release, which is detected for a period of 14 days by HPLC. In vitro studies in glial primary cultures show that incubation with 200 μg mL(-1) nanoparticles do not affect the cells' viability or proliferation, while allowing the entire population to internalize the nanoparticles. At higher concentrations, microglial cell viability is proven to be affected in response to the MP amount released. Following lateral hemisection lesions in rats, nanoparticle uptake by the spinal tissue is observed 3 h after administration. Moreover, significant differences in the locomotor output between the controls and the MP-loaded nanoparticle-treated animals one month after the lesion are observed. Therefore, MP-loaded CMCht/PAMAM dendrimer nanoparticles may prove to be useful in the reduction of the secondary injury following SCI.

Translational potential of preclinical trials of neuroprotection through pharmacotherapy for spinal cord injury

There is a need to enhance the pipeline of discovery and evaluation of neuroprotective pharmacological agents for patients with spinal cord injury (SCI). Although much effort and money has been expended on discovering effective agents for acute and subacute SCI, no agents that produce major benefit have been proven to date. The deficiencies of all aspects of the pipeline, including the basic science input and the clinical testing output, require examination to determine remedial strategies. Where has the neuroprotective/pharmacotherapy preclinical process failed and what needs to be done to achieve success? These are the questions raised in the present review, which has 2 objectives: 1) identification of articles that address issues related to the translational readiness of preclinical SCI pharmacological therapies; and 2) examination of the preclinical studies of 5 selected agents evaluated in animal models of SCI (including blunt force trauma, penetrating trauma, or ischemia). The 5 agents were riluzole, glyburide, magnesium sulfate, nimodipine, and minocycline, and these were selected because of their promise of translational readiness as determined by the North American Clinical Trials Network Consortium.

The authors found that there are major deficiencies in the effort that has been extended to coordinate and conduct preclinical neuroprotection/pharmacotherapy trials in the SCI field. Apart from a few notable exceptions such as the NIH effort to replicate promising strategies, this field has been poorly coordinated. Only a small number of articles have even attempted an overall evaluation of the neuroprotective/pharmacotherapy agents used in preclinical SCI trials. There is no consensus about how to select the agents for translation to humans on the basis of their preclinical performance and according to agreed-upon preclinical performance criteria.

In the absence of such a system and to select the next agent for translation, the Consortium has developed a Treatment Strategy Selection Committee, and this committee selected the most promising 5 agents for potential translation. The results show that the preclinical work on these 5 agents has left numerous gaps in knowledge about their preclinical performance and confirm the need for significant changes in preclinical neuroprotection/pharmacotherapy trials in SCI. A recommendation is made for the development and validation of a preclinical scoring system involving worldwide experts in preclinical and clinical SCI.

Development of less invasive neuromuscular electrical stimulation model for motor therapy in rodents

BACKGROUND

Combination therapy is essential for functional repairs of the spinal cord. Rehabilitative therapy can be considered as the key for reorganizing the nervous system after spinal cord regeneration therapy. Functional electrical stimulation has been used as a neuroprosthesis in quadriplegia and can be used for providing rehabilitative therapy to tap the capability for central nervous system reorganization after spinal cord regeneration therapy.

OBJECTIVE

To develop a less invasive muscular electrical stimulation model capable of being combined with spinal cord regeneration therapy especially for motor therapy in the acute stage after spinal cord injury.

METHODS

The tibialis anterior and gastrocnemius motor points were identified in intact anesthetized adult female Fischer rats, and stimulation needle electrodes were percutaneously inserted into these points. Threshold currents for visual twitches were obtained upon stimulation using pulses of 75 or 8 kHz for 200 ms. Biphasic pulse widths of 20, 40, 80, 100, 300, and 500 µs per phase were used to determine strength-duration curves. Using these parameters and previously obtained locomotor electromyogram data, stimulations were performed on bilateral joint muscle pairs to produce reciprocal flexion/extension movements of the ankle for 15 minutes while three-dimensional joint kinematics were assessed.

RESULTS

Rhythmic muscular electrical stimulation with needle electrodes was successfully done, but decreased range of motion (ROM) over time. High-frequency and high-amplitude stimulation was also shown to be effective in alleviating decreases in ROM due to muscle fatigue.

CONCLUSIONS

This model will be useful for investigating the ability of rhythmic muscular electrical stimulation therapy to promote motor recovery, in addition to the efficacy of combining treatments with spinal cord regeneration therapy after spinal cord injuries.

Translating preclinical approaches into human application

In recent decades, several novel approaches of spinal cord repair have revealed promising findings in animal models. However, for a successful translation of these into a clinical trial in humans the specific conditions pertaining to human spinal cord injuries (SCI) have to be appreciated. Firstly, transection of the spinal cord is commonly applied in animal models, whereas spinal cord contusion is the predominant type of injury in humans, and generally leads to more extensive injury in two to three spinal cord segments. Secondly, the quadrupedal organization of locomotion in animals and the more complex autonomic functions in humans challenge the translation of animal behavior into recovery from human SCI. Thirdly, so far, no adequate animal model has been developed to resemble spastic movement disorder in human SCI. Fourthly, the extensive damage to spinal motor neurons and nerve roots in human cervical and thoracolumbar in spine trauma is but little addressed in current translational studies. This damage has direct implications for rehabilitation and repair strategies. Fifthly, there is increasing evidence for a neuronal dysfunction below the level of the lesion in chronic complete SCI. The relevance of this dysfunction for a regeneration-inducing treatment needs to be investigated. Lastly, an approach to facilitate an appropriate reconnection of regenerating tract fibers by functional training in the postacute stage has yet to be confirmed.

Spinal cord bypass surgery with intercostal and spinal accessory nerves: an anatomical feasibility study in human cadavers

OBJECT

Despite extensive study, no meaningful progress has been made in encouraging healing and recovery across the site of spinal cord injury (SCI) in humans. Spinal cord bypass surgery is an unconventional strategy in which intact peripheral nerves rostral to the level of injury are transferred into the spinal cord below the injury. This report details the feasibility of using spinal accessory nerves to bypass cervical SCI and intercostal nerves to bypass thoracolumbar SCI in human cadavers.

METHODS

Twenty-three human cadavers underwent cervical and/or lumbar laminectomy and dural opening to expose the cervical cord and/or conus medullaris. Spinal accessory nerves were harvested from the Erb point to the origin of the nerve's first major branch into the trapezius. Intercostal nerves from the T6-12 levels were dissected from the lateral border of paraspinal muscles to the posterior axillary line. The distal ends of dissected nerves were then transferred medially and sequentially inserted 4 mm deep into the ipsilateral cervical cord (spinal accessory nerve) or conus medullaris (intercostals). The length of each transferred nerve was measured, and representative distal and proximal cross-sections were preserved for axonal counting.

RESULTS

Spinal accessory nerves were consistently of sufficient length to be transferred to caudal cervical spinal cord levels (C4-8). Similarly, intercostal nerves (from T-7 to T-12) were of sufficient length to be transferred in a tension-free manner to the conus medullaris. Spinal accessory data revealed an average harvested nerve length of 15.85 cm with the average length needed to reach C4-8 of 4.7, 5.9, 6.5, 7.1, and 7.8 cm. The average length of available intercostal nerve from each thoracic level compared with the average length required to reach the conus medullaris in a tension-free manner was determined to be as follows (available, required in cm): T-7 (18.0, 14.5), T-8 (18.7, 11.7), T-9 (18.8, 9.0), T-10 (19.6, 7.0), T-11 (18.8, 4.6), and T-12 (15.8, 1.5). The number of myelinated axons present on cross-sectional analysis predictably decreased along both spinal accessory and intercostal nerves as they coursed distally.

CONCLUSIONS

Both spinal accessory and intercostal nerves, accessible from a posterior approach in the prone position, can be successfully harvested and transferred to their respective targets in the cervical spinal cord and conus medullaris. As expected, the number of axons available to grow into the spinal cord diminishes distally along each nerve. To maximize axon "bandwidth" in nerve bypass procedures, the most proximal section of the nerve that can be transferred in a tension-free manner to a spinal level caudal to the level of injury should be implanted. This study supports the feasibility of SAN and intercostal nerve transfer as a means of treating SCI and may assist in the preoperative selection of candidates for future human clinical trials of cervical and thoracolumbar SCI bypass surgery.

Motoneuron model of self-sustained firing after spinal cord injury

Under many conditions spinal motoneurons produce plateau potentials, resulting in self-sustained firing and providing a mechanism for translating short-lasting synaptic inputs into long-lasting motor output. During the acute-stage of spinal cord injury (SCI), the endogenous ability to generate plateaus is lost; however, during the chronic-stage of SCI, plateau potentials reappear with prolonged self-sustained firing that has been implicated in the development of spasticity. In this work, we extend previous modeling studies to systematically investigate the mechanisms underlying the generation of plateau potentials in motoneurons, including the influences of specific ionic currents, the morphological characteristics of the soma and dendrite, and the interactions between persistent inward currents and synaptic input. In particular, the goal of these computational studies is to explore the possible interactions between morphological and electrophysiological changes that occur after incomplete SCI. Model results predict that some of the morphological changes generally associated with the chronic-stage for some types of spinal cord injuries can cause a decrease in self-sustained firing. This and other computational results presented here suggest that the observed increases in self-sustained firing following some types of SCI may occur mainly due to changes in membrane conductances and changes in synaptic activity, particularly changes in the strength and timing of inhibition.

Olfactory and respiratory lamina propria transplantation after spinal cord transection in rats: effects on functional recovery and axonal regeneration

Spinal cord injury (SCI) has very poor clinical prospects, resulting in irreversible loss of function below the injury site. Although applied in clinical trials, olfactory ensheathing cells transplantation (OEC) derived from lamina propria (OLP) is still a controversial repair strategy. The present study explored the efficacy of OLP or respiratory lamina propria (RLP) transplantation and the optimum period after SCI for application of this potential therapy. Adult male rats were submitted to spinal cord transection and underwent acute, 2-week or 4-week post-injury transplantation with pieces of OLP (containing OECs) or RLP (without OECs). After grafting, animals with OLP and RLP showed discrete and similar hindlimb motor improvement, with comparable spinal cord tissue sparing and sprouting in the lesion area. Acute transplantation of OLP and RLP seems to foster limited supraspinal axonal regeneration as shown by the presence of neurons stained by retrograde tracing in the brainstem nuclei. A larger number of 5-HT positive fibers were found in the cranial stump of the OLP and RLP groups compared to the lesion and caudal regions. Calcitonin gene-related peptide fibers were present in considerable numbers at the SCI site in both types of transplantation. Our results failed to verify differences between acute, 2-week and 4-week delayed transplantation of OLP and RLP, suggesting that the limited functional and axon reparative effects observed could not be exclusively related to OECs. A greater understanding of the effects of these tissue grafts is necessary to strengthen the rationale for application of this treatment in humans.

Neurotrophins: potential therapeutic tools for the treatment of spinal cord injury

Spinal cord injury permanently disrupts neuroanatomical circuitry and can result in severe functional deficits. These functional deficits, however, are not immutable and spontaneous recovery occurs in some patients. It is highly likely that this recovery is dependent upon spared tissue and the endogenous plasticity of the central nervous system. Neurotrophic factors are mediators of neuronal plasticity throughout development and into adulthood, affecting proliferation of neuronal precursors, neuronal survival, axonal growth, dendritic arborization and synapse formation. Neurotrophic factors are therefore excellent candidates for enhancing axonal plasticity and regeneration after spinal cord injury. Understanding growth factor effects on axonal growth and utilizing them to alter the intrinsic limitations on regenerative growth will provide potent tools for the development of translational therapeutic interventions for spinal cord injury.

Biomarkers for severity of spinal cord injury in the cerebrospinal fluid of rats

One of the major challenges in management of spinal cord injury (SCI) is that the assessment of injury severity is often imprecise. Identification of reliable, easily quantifiable biomarkers that delineate the severity of the initial injury and that have prognostic value for the degree of functional recovery would significantly aid the clinician in the choice of potential treatments. To find such biomarkers we performed quantitative liquid chromatography-mass spectrometry (LC-MS/MS) analyses of cerebrospinal fluid (CSF) collected from rats 24 h after either a moderate or severe SCI. We identified a panel of 42 putative biomarkers of SCI, 10 of which represent potential biomarkers of SCI severity. Three of the candidate biomarkers, Ywhaz, Itih4, and Gpx3 were also validated by Western blot in a biological replicate of the injury. The putative biomarkers identified in this study may potentially be a valuable tool in the assessment of the extent of spinal cord damage.

The extracellular matrix glycoprotein tenascin-C promotes locomotor recovery after spinal cord injury in adult zebrafish

Adult zebrafish, by virtue of exhibiting spontaneous recovery after spinal lesion, have evolved into a paradigmatic vertebrate model system to identify novel genes vital for successful regeneration after spinal cord injury. Due to a remarkable level of conservation between zebrafish and human genomes, such genes, once identified, could point to possibilities for addressing the multiple issues on how to deal with functional recovery after spinal cord injury in humans. In the current study, the extracellular matrix glycoprotein tenascin-C was studied in the zebrafish spinal cord injury model to assess the often disparate functions of this multidomain molecule under in vivo conditions. This in vivo study was deemed necessary since in vitro studies had shown discrepant functional effects on neurite outgrowth: tenascin-C inhibits neurite outgrowth when presented as a molecular barrier adjacent to a conducive substrate, but enhances neurite outgrowth when presented as a uniform substrate. Thus, our current study addresses the question as to which of these features prevails in vivo: whether tenascin-C reduces or enhances axonal regrowth after injury in a well accepted vertebrate model of spinal cord injury. We show upregulation of tenascin-C expression in regenerating neurons of the nucleus of median longitudinal fascicle (NMLF) in the brainstem and spinal motoneurons. Inhibition of tenascin-C expression by antisense oligonucleotide (morpholino) resulted in impaired locomotor recovery, reduced regrowth of axons from brainstem neurons and reduced synapse formation by the regrowing brainstem axons on spinal motoneurons, all vital indicators of regeneration. Our results thus point to an advantageous role of tenascin-C in promoting spinal cord regeneration, by promoting axonal regrowth and synapse formation in the spinal cord caudal to the lesion site after injury.

Intermittent fasting improves functional recovery after rat thoracic contusion spinal cord injury

Spinal cord injury (SCI) often results in a loss of motor and sensory function. Currently there are no validated effective clinical treatments. Previously we found in rats that dietary restriction, in the form of every-other-day fasting (EODF), started prior to (pre-EODF), or after (post-EODF) an incomplete cervical SCI was neuroprotective, increased plasticity, and promoted motor recovery. Here we examined if EODF initiated prior to, or after, a T10 thoracic contusion injury would similarly lead to enhanced functional recovery compared to ad libitum feeding. Additionally, we tested if a group fed every day (pair-fed), but with the same degree of restriction as the EODF animals (∼25% calorie restricted), would also promote functional recovery, to examine if EODF's effect is due to overall calorie restriction, or is specific to alternating sequences of 24-h fasts and ad libitum eating periods. Behaviorally, both pre- and post-EODF groups exhibited better functional recovery in the regularity indexed BBB ambulatory assessment, along with several parameters of their walking pattern measured with the CatWalk device, compared to both the ad-libitium-fed group as well as the pair-fed group. Several histological parameters (intensity and symmetry of serotonin immunostaining caudal to the injury and gray matter sparing) correlated with functional outcome; however, no group differences were observed. Thus besides the beneficial effects of EODF after a partial cervical SCI, we now report that alternating periods of fasting (but not pair-fed) also promotes improved hindlimb locomotion after thoracic spinal cord contusion, demonstrating its robust effect in two different injury models.

The acute administration of eicosapentaenoic acid is neuroprotective after spinal cord compression injury in rats

The aim of the present study was to investigate the effects of treatment with eicosapentaenoic acid (EPA) after spinal cord compression injury in adult rats. Saline or EPA (250 nmol/kg) was administered intravenously 30 min after compression injury. Locomotor recovery was assessed daily using the BBB open-field locomotor score. One week after injury, animals were sacrificed and the spinal cord tissue containing the compression epicenter, and the adjacent rostral and caudal segments, was immunostained using specific markers for neurons, oligodendrocytes, axonal injury, and macrophages/microglia. Administration of EPA resulted in decreased axonal injury and increased neuronal and oligodendrocyte survival, in the lesion epicenter and adjacent tissue. The behavioural assessment mirrored the neuroprotective effects and showed a significantly improved functional recovery in animals treated with EPA compared to the saline-treated controls over the 7-day period. These observations suggest that EPA has neuroprotective properties when administered after spinal cord trauma.

Ethics, health care and spinal cord injury: research, practice and finance

Dating back to ancient times, mankind has been absorbed with 'doing the right thing', that is, behaving in ways approved by the society and the culture during the era in which they lived. This has been and still is especially true for the medical and related health-care professions. Laws and professional codes have evolved over the years that provide guidelines as to how physicians should treat patients, beginning with the one authored by Hippocrates. Only more recently, however, have laws and codes been created to cover health-care research and the advances in health-care practice that have been brought to light by that research. Although these discoveries have clearly impacted the quality of life and duration of life for people with spinal cord injury and other maladies, they have also raised questions that go beyond the science. Questions such as when, why, how and for how long should such treatments be applied often relate more to what a society and its culture will condone and the answers can differ and have differed among societies depending on the prevailing ethics and morals. Modern codes and laws have been created so that the trust people have traditionally placed in their healers will not be violated or misused as happened during wars past, especially in Nazi Germany. This paper will trace the evolution of the rules that medical researchers, practitioners and payers for treatment must now follow and explain why guiding all their efforts that honesty must prevail.