RESUMEN

Many individuals with spinal cord injury live with debilitating chronic pain that may be neuropathic, nociceptive, or a combination of both in nature. Identification of brain regions demonstrating altered connectivity associated with the type and severity of pain experience may elucidate underlying mechanisms, as well as treatment targets. Resting state and sensorimotor task-based magnetic resonance imaging data were collected in 37 individuals with chronic spinal cord injury. Seed-based correlations were utilized to identify resting state functional connectivity of regions with established roles in pain processing: the primary motor and somatosensory cortices, cingulate, insula, hippocampus, parahippocampal gyri, thalamus, amygdala, caudate, putamen, and periaqueductal gray matter. Resting state functional connectivity alterations and task-based activation associated with individuals' pain type and intensity ratings on the International Spinal Cord Injury Basic Pain Dataset (0-10 scale) were evaluated. We found that intralimbic and limbostriatal resting state connectivity alterations are uniquely associated with neuropathic pain severity, whereas thalamocortical and thalamolimbic connectivity alterations are associated specifically with nociceptive pain severity. The joint effect and contrast of both pain types were associated with altered limbocortical connectivity. No significant differences in task-based activation were identified. These findings suggest that the experience of pain in individuals with spinal cord injury may be associated with unique alterations in resting state functional connectivity dependent upon pain type.

Asunto(s)

Neuralgia , Dolor Nociceptivo , Traumatismos de la Médula Espinal , Humanos , Encéfalo , Imagen por Resonancia Magnética/métodos , Neuralgia/diagnóstico por imagen , Neuralgia/etiología , Traumatismos de la Médula Espinal/complicaciones , Traumatismos de la Médula Espinal/diagnóstico por imagen

RESUMEN

OBJECTIVE: To identify microRNA biomarkers and clinical factors associated with neuropathic pain after spinal cord injury. DESIGN: Cross-sectional, secondary analysis of baseline data collected from ongoing clinical studies. Using a genome-wide microRNA screening approach, we studied differential microRNA expression in serum from 43 adults with spinal cord injury enrolled in ongoing clinical studies. Least squares regression was used to identify associations between microRNA expression, clinical factors, and neuropathic pain severity. SETTING: Community-dwelling individuals with spinal cord injury. PARTICIPANTS: Participants (N=43) were at least 18 years old with spinal cord injury, with 28 reporting neuropathic pain and 15 reporting no neuropathic pain. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Pain presence, type, and intensity were assessed with the International Spinal Cord Injury Pain Basic Data Set. Serum microRNA normalized deep sequencing counts were quantified from blood samples. Participant demographic factors, injury characteristics, medication use, and health habits were collected via questionnaire. RESULTS: miR-338-5p expression and history of cigarette smoking were associated with and explained 37% of the variance in neuropathic pain severity (R2=0.37, F2,18=5.31, P=.02) independent of other clinical factors. No association was identified between miR-338-5p levels and nociceptive pain severity. CONCLUSIONS: Our findings suggest that miR-338-5p and cigarette smoking may both play a role in the development or maintenance of neuropathic pain after spinal cord injury. While additional work is needed to confirm these findings, validated target analysis suggests a neuroprotective role of miR-338-5p in modulating neuroinflammation and neuronal apoptosis and that its downregulation may result in maladaptive neuroplastic mechanisms contributing to neuropathic pain after spinal cord injury.

Asunto(s)

Fumar Cigarrillos , MicroARNs , Neuralgia , Traumatismos de la Médula Espinal , Adolescente , Estudios Transversales , Humanos , MicroARNs/genética , MicroARNs/metabolismo , Neuralgia/genética , Traumatismos de la Médula Espinal/complicaciones , Traumatismos de la Médula Espinal/genética , Traumatismos de la Médula Espinal/metabolismo

RESUMEN

Neuropathic pain in spinal cord injury (SCI) is associated with inflammation in both the peripheral and central nervous system (CNS), which may contribute to the initiation and maintenance of persistent pain. An understanding of factors contributing to neuroinflammation may lead to new therapeutic targets for neuropathic pain. Moreover, novel circulating biomarkers of neuropathic pain may facilitate earlier and more effective treatment. MicroRNAs (miRNAs) are short, non-coding single-stranded RNA that have emerged as important biomarkers and molecular mediators in physiological and pathological conditions. Using a genome-wide miRNA screening approach, we studied differential miRNA expression in plasma from 68 healthy, community-dwelling adults with and without SCI enrolled in ongoing clinical studies. We detected 2367 distinct miRNAs. Of these, 383 miRNAs were differentially expressed in acute SCI or chronic SCI versus no SCI and 71 were differentially expressed in chronic neuropathic pain versus no neuropathic pain. We selected homo sapiens (hsa)-miR-19a-3p and hsa-miR-19b-3p for additional analysis based on p-value, fold change, and their known role as regulators of neuropathic pain and neuroinflammation. Both hsa-miR-19a-3p and hsa-miR-19b-3p levels were significantly higher in those with chronic SCI and severe neuropathic pain versus those with chronic SCI and no neuropathic pain. In confirmatory studies, both hsa-miR-19a-3p and hsa-miR-19b-3p have moderate to strong discriminative ability to distinguish between those with and without pain. After adjusting for opioid use, hsa-miR-19b-3p levels were positively associated with pain interference with mood. Because hsa-miR-19 levels have been shown to change in response to exercise, folic acid, and resveratrol, these studies suggest that miRNAs are potential targets of therapeutic interventions.

RESUMEN

Posttraumatic syringomyelia (PTS) is a serious condition of progressive expansion of spinal cord cysts, affecting patients with spinal cord injury years after injury. To evaluate neural cell therapy to prevent cyst expansion and potentially replace lost neurons, we developed a rat model of PTS. We combined contusive trauma with subarachnoid injections of blood, causing tethering of the spinal cord to the surrounding vertebrae, resulting in chronically expanding cysts. The cysts were usually located rostral to the injury, extracanalicular, lined by astrocytes. T2*-weighted magnetic resonance imaging (MRI) showed hyperintense fluid-filled cysts but also hypointense signals from debris and iron-laden macrophages/microglia. Two types of human neural stem/progenitor cells-fetal neural precursor cells (hNPCs) and neuroepithelial-like stem cells (hNESCs) derived from induced pluripotent stem cells-were transplanted to PTS cysts. Cells transplanted into cysts 10 weeks after injury survived at least 10 weeks, migrated into the surrounding parenchyma, but did not differentiate during this period. The cysts were partially obliterated by the cells, and cyst walls often merged with thin layers of cells in between. Cyst volume measurements with MRI showed that the volumes continued to expand in sham-transplanted rats by 102%, while the cyst expansion was effectively prevented by hNPCs and hNESCs transplantation, reducing the cyst volumes by 18.8% and 46.8%, respectively. The volume reductions far exceeded the volume of the added human cells. Thus, in an animal model closely mimicking the clinical situation, we provide proof-of-principle that transplantation of human neural stem/progenitor cells can be used as treatment for PTS.

Asunto(s)

Modelos Animales de Enfermedad , Células Madre Pluripotentes Inducidas/trasplante , Traumatismos de la Médula Espinal/terapia , Trasplante de Células Madre/métodos , Siringomielia/terapia , Vértebras Torácicas/lesiones , Animales , Células Cultivadas , Células Madre Embrionarias/trasplante , Femenino , Humanos , Ratas , Ratas Sprague-Dawley , Traumatismos de la Médula Espinal/complicaciones , Traumatismos de la Médula Espinal/patología , Siringomielia/etiología , Siringomielia/patología

RESUMEN

OBJECTIVE Surgically created lesions of the spinal cord dorsal root entry zone (DREZ) to relieve central pain after spinal cord injury (SCI) have historically been performed at and cephalad to, but not below, the level of SCI. This study was initiated to investigate the validity of 3 proposed concepts regarding the DREZ in SCI central pain: 1) The spinal cord DREZ caudal to the level of SCI can be a primary generator of SCI below-level central pain. 2) Neuronal transmission from a DREZ that generates SCI below-level central pain to brain pain centers can be primarily through sympathetic nervous system (SNS) pathways. 3) Perceived SCI below-level central pain follows a unique somatotopic map of DREZ pain-generators. METHODS Three unique patients with both intractable SCI below-level central pain and complete spinal cord transection at the level of SCI were identified. All 3 patients had previously undergone surgical intervention to their spinal cords-only cephalad to the level of spinal cord transection-with either DREZ microcoagulation or cyst shunting, in failed attempts to relieve their SCI below-level central pain. Subsequent to these surgeries, DREZ lesioning of the spinal cord solely caudal to the level of complete spinal cord transection was performed using electrical intramedullary guidance. The follow-up period ranged from 1 1/2 to 11 years. RESULTS All 3 patients in this study had complete or near-complete relief of all below-level neuropathic pain. The analyzed electrical data confirmed and enhanced a previously proposed somatotopic map of SCI below-level DREZ pain generators. CONCLUSIONS The results of this study support the following hypotheses. 1) The spinal cord DREZ caudal to the level of SCI can be a primary generator of SCI below-level central pain. 2) Neuronal transmission from a DREZ that generates SCI below-level central pain to brain pain centers can be primarily through SNS pathways. 3) Perceived SCI below-level central pain follows a unique somatotopic map of DREZ pain generators.

Asunto(s)

Neuralgia/fisiopatología , Neuralgia/cirugía , Procedimientos Neuroquirúrgicos , Traumatismos de la Médula Espinal/fisiopatología , Traumatismos de la Médula Espinal/cirugía , Raíces Nerviosas Espinales/cirugía , Estudios de Seguimiento , Humanos , Masculino , Microcirugia , Persona de Mediana Edad , Modelos Neurológicos , Vías Nerviosas/diagnóstico por imagen , Vías Nerviosas/fisiopatología , Neuralgia/diagnóstico por imagen , Neuralgia/etiología , Manejo del Dolor , Médula Espinal/diagnóstico por imagen , Médula Espinal/fisiopatología , Traumatismos de la Médula Espinal/complicaciones , Traumatismos de la Médula Espinal/diagnóstico por imagen , Raíces Nerviosas Espinales/diagnóstico por imagen , Raíces Nerviosas Espinales/fisiopatología , Transmisión Sináptica

RESUMEN

Central neuropathic pain is a debilitating outcome of spinal cord injury (SCI) and current treatments to alleviate this pain condition are ineffective. A growing body of literature suggests that activating adenosine A2A receptors (A2ARs) decreases the production of proinflammatory cytokines and increases the production of anti-inflammatory cytokines. Here, the effect of administering intrathecal A2AR agonists on central neuropathic pain was measured using hindpaw mechanical allodynia in a rat model of SCI termed spinal neuropathic avulsion pain (SNAP). Other models of SCI cause extensive damage to the spinal cord, resulting in paralysis and health problems. SNAP rats with unilateral low thoracic (T13)/high lumbar (L1) dorsal root avulsion develop below-level bilateral allodynia, without concomitant motor or health problems. A single intrathecal injection of the A2AR agonist 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamido adenosine HCl (CGS21680) reversed SCI-induced allodynia for at least 6 weeks. The reversal is likely in part mediated by interleukin (IL)-10, as intrathecally administering neutralizing IL-10 antibodies 1 week after CGS21680 abolished the anti-allodynic effect of CGS21680. Dorsal spinal cord tissue from the ipsilateral site of SCI (T13/L1) was assayed 1 and 6 weeks after CGS21680 for IL-10, CD11b, and tumor necrosis factor (TNF) gene expression. CGS21680 treatment did not change IL-10 gene expression but did significantly decrease CD11b and TNF gene expression at both timepoints. A second A2AR agonist, 4-(3-(6-amino-9-(5-cyclopropylcarbamoyl-3,4-dihydroxytetrahydrofuran-2-yl)-9H-purin-2-yl)prop-2-ynyl)piperidine-1-carboxylic acid methyl ester (ATL313), was also able to significantly prevent and reverse SCI-induced allodynia for several weeks after a single intrathecal injection, providing converging lines of evidence of A2AR involvement. The enduring pain reversal after a single intrathecal injection of A2AR agonists suggests that A2AR agonists could be exciting new candidates for treating SCI-induced central neuropathic pain.

Asunto(s)

Agonistas del Receptor de Adenosina A2/uso terapéutico , Adenosina/análogos & derivados , Hiperalgesia/tratamiento farmacológico , Neuralgia/tratamiento farmacológico , Fenetilaminas/uso terapéutico , Traumatismos de la Médula Espinal/complicaciones , Adenosina/uso terapéutico , Animales , Anticuerpos Neutralizantes/farmacología , Hiperalgesia/etiología , Hiperalgesia/fisiopatología , Interleucina-10/inmunología , Masculino , Neuralgia/etiología , Neuralgia/fisiopatología , Ratas , Ratas Sprague-Dawley , Traumatismos de la Médula Espinal/fisiopatología

RESUMEN

Central neuropathic pain (CNP) is a pervasive, debilitating problem that impacts thousands of people living with central nervous system disorders, including spinal cord injury (SCI). Current therapies for treating this type of pain are ineffective and often have dose-limiting side effects. Although opioids are one of the most commonly used CNP treatments, recent animal literature has indicated that administering opioids shortly after a traumatic injury can actually have deleterious effects on long-term health and recovery. In order to study the deleterious effects of administering morphine shortly after trauma, we employed our low thoracic (T13) dorsal root avulsion model (Spinal Neuropathic Avulsion Pain, SNAP). Administering a weeklong course of 10mg/kg/day morphine beginning 24h after SNAP resulted in amplified mechanical allodynia. Co-administering the non-opioid toll-like receptor 4 (TLR4) antagonist (+)-naltrexone throughout the morphine regimen prevented morphine-induced amplification of SNAP. Exploration of changes induced by early post-trauma morphine revealed that this elevated gene expression of TLR4, TNF, IL-1ß, and NLRP3, as well as IL-1ß protein at the site of spinal cord injury. These data suggest that a short course of morphine administered early after spinal trauma can exacerbate CNP in the long term. TLR4 initiates this phenomenon and, as such, may be potential therapeutic targets for preventing the deleterious effects of administering opioids after traumatic injury.

Asunto(s)

Analgésicos Opioides/administración & dosificación , Hiperalgesia/metabolismo , Morfina/administración & dosificación , Neuralgia/metabolismo , Traumatismos de la Médula Espinal/metabolismo , Receptor Toll-Like 4/metabolismo , Animales , Hiperalgesia/complicaciones , Masculino , Naltrexona/administración & dosificación , Neuralgia/complicaciones , Ratas Sprague-Dawley , Traumatismos de la Médula Espinal/complicaciones , Receptor Toll-Like 4/antagonistas & inhibidores

RESUMEN

UNLABELLED: Central neuropathic pain (CNP) is a debilitating consequence of central nervous system damage for which current treatments are ineffective. To explore mechanisms underlying CNP, we developed a rat model involving T13/L1 dorsal root avulsion. The resultant dorsal horn damage creates bilateral below-level (L4-L6) mechanical allodynia. This allodynia, termed spinal neuropathic avulsion pain, occurs in the absence of confounding paralysis. To characterize this model, we undertook a series of studies aimed at defining whether spinal neuropathic avulsion pain could be reversed by any of 3 putative glial activation inhibitors, each with distinct mechanisms of action. Indeed, the phosphodiesterase inhibitor propentofylline, the macrophage migration inhibitory factor inhibitor ibudilast, and the toll-like receptor 4 antagonist (+)-naltrexone each reversed below-level allodynia bilaterally. Strikingly, none of these impacted spinal neuropathic avulsion pain upon first administration but required 1 to 2 weeks of daily administration before pain reversal was obtained. Given reversal of CNP by each of these glial modulatory agents, these results suggest that glia contribute to the maintenance of such pain and enduring release of macrophage migration inhibitory factor and endogenous agonists of toll-like receptor 4 is important for sustaining CNP. The markedly delayed efficacy of all 3 glial modulatory drugs may prove instructive for interpretation of apparent drug failures after shorter dosing regimens. PERSPECTIVE: CNP that develops after trauma is often described by patients as severe and intolerable. Unfortunately, current treatments are not effective. This work suggests that using pharmacologic treatments that target glial cells could be an effective clinical treatment for CNP.

Asunto(s)

Hiperalgesia/etiología , Neuralgia/etiología , Neuroglía/efectos de los fármacos , Fármacos Neuroprotectores/farmacología , Animales , Modelos Animales de Enfermedad , Masculino , Naltrexona/farmacología , Antagonistas de Narcóticos/farmacología , Inhibidores de Fosfodiesterasa/farmacología , Piridinas/farmacología , Radiculopatía/complicaciones , Ratas , Ratas Sprague-Dawley , Xantinas/farmacología

RESUMEN

To validate human neural precursor cells (NPCs) as potential donor cells for transplantation therapy after spinal cord injury (SCI), we investigated the effect of NPCs, transplanted as neurospheres, in two different rat SCI models. Human spinal cord-derived NPCs (SC-NPCs) transplanted 9 days after spinal contusion injury enhanced hindlimb recovery, assessed by the BBB locomotor test. In spinal compression injuries, SC-NPCs transplanted immediately or after 1 week, but not 7 weeks after injury, significantly improved hindlimb recovery compared to controls. We could not detect signs of mechanical allodynia in transplanted rats. Four months after transplantation, we found more human cells in the host spinal cord than were transplanted, irrespective of the time of transplantation. There was no focal tumor growth. In all groups the vast majority of NPCs differentiated into astrocytes. Importantly, the number of surviving rat spinal cord neurons was highest in groups transplanted acutely and subacutely, which also showed the best hindlimb function. This suggests that transplanted SC-NPCs improve the functional outcome by a neuroprotective effect. We conclude that SC-NPCs reliably enhance the functional outcome after SCI if transplanted acutely or subacutely, without causing allodynia. This therapeutic effect is mainly the consequence of a neuroprotective effect of the SC-NPCs.

Asunto(s)

Células-Madre Neurales/fisiología , Células-Madre Neurales/trasplante , Traumatismos de la Médula Espinal/cirugía , Médula Espinal/citología , Animales , Modelos Animales de Enfermedad , Femenino , Feto , Regulación de la Expresión Génica/fisiología , Proteínas de Choque Térmico HSP27/metabolismo , Miembro Posterior/fisiopatología , Humanos , Actividad Motora/fisiología , Proteínas del Tejido Nervioso/metabolismo , Umbral del Dolor/fisiología , Ratas , Traumatismos de la Médula Espinal/patología , Traumatismos de la Médula Espinal/fisiopatología , Factores de Tiempo

RESUMEN

Studies in model organisms constitute the basis of our understanding of the principal molecular mechanisms of cell fate determination in the developing central nervous system. Considering the emergent applications in stem cell-based regenerative medicine, it is important to demonstrate conservation of subtype specific gene expression programs in human as compared to model vertebrates. We have examined the expression patterns of key regulatory genes in neural progenitor cells and their neuronal and glial descendants in the developing human spinal cord, hindbrain, and midbrain, and compared these with developing mouse and chicken embryos. As anticipated, gene expression patterns are highly conserved between these vertebrate species, but there are also features that appear unique to human development. In particular, we find that neither tyrosine hydroxylase nor Nurr1 are specific markers for mesencephalic dopamine neurons, as these genes also are expressed in other neuronal subtypes in the human ventral midbrain and in human embryonic stem cell cultures directed to differentiate towards a ventral mesencephalic identity. Moreover, somatic motor neurons in the ventral spinal cord appear to be produced by two molecularly distinct ventral progenitor populations in the human, raising the possibility that the acquisition of unique ventral progenitor identities may have contributed to the emergence of neural subtypes in higher vertebrates.

Asunto(s)

Mesencéfalo/embriología , Células-Madre Neurales/citología , Tubo Neural/embriología , Rombencéfalo/embriología , Médula Espinal/embriología , Animales , Diferenciación Celular , Células Cultivadas , Embrión de Pollo , Perfilación de la Expresión Génica , Regulación del Desarrollo de la Expresión Génica , Humanos , Mesencéfalo/citología , Ratones , Neuronas Motoras/citología , Proteínas del Tejido Nervioso/genética , Proteínas del Tejido Nervioso/metabolismo , Tubo Neural/citología , Neuronas/citología , Miembro 2 del Grupo A de la Subfamilia 4 de Receptores Nucleares/genética , Rombencéfalo/citología , Médula Espinal/citología , Tirosina 3-Monooxigenasa/genética

RESUMEN

Central neuropathic pain is associated with many disease states including multiple sclerosis, stroke, and spinal cord injury, and is poorly managed. One type of central neuropathic pain that is particularly debilitating and challenging to treat is pain that occurs below the level of injury (below-level pain). The study of central neuropathic pain is commonly performed using animal models of stroke and spinal cord injury. Most of the spinal cord injury models currently being used were originally developed to model the gross physiological impact of clinical spinal cord injury. In contrast, the T13/L1 dorsal root avulsion model of spinal cord injury described here was developed specifically for the study of central pain, and as such, was developed to minimize confounding complications, such as paralysis, urinary tract infections, and autotomy. As such, this model induces robust and reliable hindpaw mechanical allodynia. Two versions of the model are described. The first is optimal for testing systemically administered pharmacological manipulations. The second was developed to accommodate intrathecal application of pharmacological manipulations. This model provides an additional means by which to investigate central pain states associated with spinal cord injury, including below-level pain. Finally, a brief discussion of at-level pain measurement is described as it has been suggested in the literature that the mechanisms underlying below- and at-level pain are different.

Asunto(s)

Neuralgia/metabolismo , Dimensión del Dolor/métodos , Raíces Nerviosas Espinales/fisiopatología , Animales , Modelos Animales de Enfermedad , Hiperalgesia/etiología , Hiperalgesia/metabolismo , Neuralgia/fisiopatología , Umbral del Dolor/fisiología , Traumatismos de la Médula Espinal/fisiopatología

RESUMEN

Culturing stem cells as free-floating aggregates in suspension facilitates large-scale production of cells in closed systems, for clinical use. To comply with GMP standards, the use of substances such as proteolytic enzymes should be avoided. Instead of enzymatic dissociation, the growing cell aggregates may be mechanically cut at passage, but available methods are not compatible with large-scale cell production and hence translation into the clinic becomes a severe bottle-neck. We have developed the Biogrid device, which consists of an array of micrometerscale knife edges, micro-fabricated in silicon, and a manifold in which the microgrid is placed across the central fluid channel. By connecting one side of the Biogrid to a syringe or a pump and the other side to the cell culture, the culture medium with suspended cell aggregates can be aspirated, forcing the aggregates through the microgrid, and ejected back to the cell culture container. Large aggregates are thereby dissociated into smaller fragments while small aggregates pass through the microgrid unaffected. As proof-of-concept, we demonstrate that the Biogrid device can be successfully used for repeated passage of human neural stem/progenitor cells cultured as so-called neurospheres, as well as for passage of suspension cultures of human embryonic stem cells. We also show that human neural stem/progenitor cells tolerate transient pressure changes far exceeding those that will occur in a fluidic system incorporating the Biogrid microgrids. Thus, by using the Biogrid device it is possible to mechanically passage large quantities of cells in suspension cultures in closed fluidic systems, without the use of proteolytic enzymes.

Asunto(s)

Técnicas Analíticas Microfluídicas/métodos , Células-Madre Neurales/citología , Técnicas de Cultivo de Célula/instrumentación , Técnicas de Cultivo de Célula/métodos , Proliferación Celular , Células Cultivadas , Células Madre Embrionarias/citología , Humanos , Técnicas Analíticas Microfluídicas/instrumentación , Presión , Silicio/química

RESUMEN

Mechanical allodynia, the perception of innocuous tactile stimulation as painful, is a severe symptom of chronic pain often produced by damage to peripheral nerves. Allodynia affects millions of people and remains highly resistant to classic analgesics and therapies. Neural mechanisms for the development and maintenance of allodynia have been investigated in the spinal cord, brainstem, thalamus, and forebrain, but manipulations of these regions rarely produce lasting effects. We found that long-term alleviation of allodynic manifestations is produced by discreetly lesioning a newly discovered somatosensory representation in caudal granular insular cortex (CGIC) in the rat, either before or after a chronic constriction injury of the sciatic nerve. However, CGIC lesions alone have no effect on normal mechanical stimulus thresholds. In addition, using electrophysiological techniques, we reveal a corticospinal loop that could be the anatomical source of the influence of CGIC on allodynia.

Asunto(s)

Corteza Cerebral/fisiología , Hiperalgesia/fisiopatología , Umbral del Dolor/fisiología , Ciática/fisiopatología , Análisis de Varianza , Animales , Conducta Animal , Biotina/análogos & derivados , Biotina/metabolismo , Mapeo Encefálico , Corteza Cerebral/lesiones , Dextranos/metabolismo , Modelos Animales de Enfermedad , Electrofisiología , Potenciales Evocados Auditivos/efectos de los fármacos , Potenciales Evocados Auditivos/fisiología , Potenciales Evocados Somatosensoriales/efectos de los fármacos , Potenciales Evocados Somatosensoriales/fisiología , Lateralidad Funcional , Agonistas de Receptores de GABA-A/farmacología , Masculino , Muscimol/farmacología , Dimensión del Dolor , Umbral del Dolor/efectos de los fármacos , Estimulación Física/métodos , Tractos Piramidales/fisiología , Ratas , Ratas Sprague-Dawley , Factores de Tiempo

RESUMEN

Central neuropathic pain occurs with multiple sclerosis, stroke, and spinal cord injury (SCI). Models of SCI are commonly used to study central neuropathic pain and are excellent at modeling gross physiological changes. Our goal was to develop a rat model of central neuropathic pain by traumatizing a discrete region of the dorsal spinal cord, thereby avoiding issues including paralysis, urinary tract infection, and autotomy. To this end, dorsal root avulsion was pursued. The model was developed by first determining the number of avulsed dorsal roots sufficient to induce below-level hindpaw mechanical allodynia. This was optimally achieved by unilateral T13 and L1 avulsion, which resulted in tissue damage confined to Lissauer's tract, dorsal horn, and dorsal columns, at the site of avulsion, with no gross physical changes at other spinal levels. Behavior following avulsion was compared to that following rhizotomy of the T13 and L1 dorsal roots, a commonly used model of neuropathic pain. Avulsion induced below-level allodynia that was more robust and enduring than that seen after rhizotomy. This, plus the lack of direct spinal cord damage associated with rhizotomy, suggests that avulsion is not synonymous with rhizotomy, and that avulsion (but not rhizotomy) is a model of central neuropathic pain. The new model described here is the first to use discrete dorsal horn damage by dorsal root avulsion to create below-level bilateral central neuropathic pain.

Asunto(s)

Neuralgia/patología , Traumatismos de la Médula Espinal/patología , Raíces Nerviosas Espinales/lesiones , Raíces Nerviosas Espinales/fisiología , Animales , Masculino , Actividad Motora/fisiología , Neuralgia/etiología , Neuralgia/fisiopatología , Radiculopatía/patología , Radiculopatía/fisiopatología , Ratas , Ratas Sprague-Dawley , Traumatismos de la Médula Espinal/complicaciones , Traumatismos de la Médula Espinal/fisiopatología , Raíces Nerviosas Espinales/patología , Vértebras Torácicas

RESUMEN

OBJECT: Permanent neurological loss after spinal cord injury (SCI) is a well-known phenomenon. There has also been a growing recognition and improved understanding of the pathophysiological mechanisms of late progressive neurological loss, which may occur after SCI as a result of posttraumatic spinal cord tethering (SCT), myelomalacia, and syringomyelia. A clinical study of 404 patients sustaining traumatic SCIs and undergoing surgery to arrest a progressive myelopathy caused by SCT, with or without progressive myelomalacia and cystic cavitation (syringomyelia) was undertaken. Both objective and subjective long-term outcomes were evaluated. To the authors' knowledge, this is the first series of this size correlating long-term patient perception of outcome with long-term objective outcome analyses. METHODS: During the period from January 1993 to November 2003, 404 patients who had previously sustained traumatic SCIs underwent 468 surgeries for progressive myelopathies attributed to tethering of the spinal cord to the surrounding spinal canal, with or without myelomalacia and syrinx formation. Forty-two patients were excluded because of additional pathological entities that were known to contribute to a progressive myelopathy. All surgeries were performed by the same neurosurgeon at a single SCI treatment center and by using a consistent surgical technique of spinal cord detethering, expansion duraplasty, and when indicated, cyst shunting. RESULTS: Outcome data were collected up to 12 years postoperatively. Comparisons of pre- and postoperative American Spinal Injury Association sensory and motor index scores showed no significant change when only a single surgery was required (86% of patients). An outcome questionnaire and phone interview resulted in > 90% of patients self-assessing arrest of functional loss; > 50% of patients self-assessing improvement of function; 17 and 18% self-assessing improvement of motor and sensory functions to a point greater than that achieved at any time postinjury, respectively; 59% reporting improvement of spasticity; and 77% reporting improvement of hyperhidrosis. CONCLUSIONS: Surgery for spinal cord detethering, expansion duraplasty, and when indicated, cyst shunting, is a successful treatment strategy for arresting a progressive myelopathy related to posttraumatic SCT and syringomyelia. Results suggest that surgery leads to functional return in ~ 50% of patients, and that in some patients posttraumatic SCT limits maximal recovery of spinal cord function postinjury. A patient's perception of surgery's failure to arrest the progressive myelopathy corresponds closely with the need for repeat surgery because of retethering, cyst reexpansion, and pseudomeningocele formation.

Asunto(s)

Defectos del Tubo Neural/cirugía , Procedimientos Neuroquirúrgicos , Traumatismos de la Médula Espinal/cirugía , Siringomielia/cirugía , Adolescente , Adulto , Anciano , Dolor de Espalda , Estudios de Seguimiento , Humanos , Hiperhidrosis , Imagen por Resonancia Magnética , Persona de Mediana Edad , Neuronas Motoras/fisiología , Espasticidad Muscular , Defectos del Tubo Neural/etiología , Defectos del Tubo Neural/patología , Complicaciones Posoperatorias , Reoperación , Células Receptoras Sensoriales/fisiología , Traumatismos de la Médula Espinal/complicaciones , Traumatismos de la Médula Espinal/patología , Encuestas y Cuestionarios , Siringomielia/etiología , Siringomielia/patología , Resultado del Tratamiento , Adulto Joven

RESUMEN

Transplantation of human neural stem cells (NSCs) and their derivatives is a promising future treatment for neurodegenerative disease and traumatic nervous system lesions. An important issue is what kind of immunological reaction the cellular transplant and host interaction will result in. Previously, we reported that human NSCs, despite expressing MHC class I and class II molecules, do not trigger an allogeneic T cell response. Here, the immunocompetence of human NSCs, as well as differentiated neural cells, was further studied. Astrocytes expressed both MHC class I and class II molecules to a degree equivalent to that of the NSCs, whereas neurons expressed only MHC class I molecules. Neither the NSCs nor the differentiated cells triggered an allogeneic lymphocyte response. Instead, these potential donor NSCs and astrocytes, but not the neurons, exhibited a suppressive effect on an allogeneic immune response. The suppressive effect mediated by NSCs most likely involves cell-cell interaction. When the immunogenicity of human NSCs was tested in an acute spinal cord injury model in rodent, a xenogeneic rejection response was triggered. Thus, human NSCs and their derived astrocytes do not initiate, but instead suppress, an allogeneic response, while they cannot block a graft rejection in a xenogeneic setting.

Asunto(s)

Astrocitos/trasplante , Neuronas/trasplante , Trasplante de Células Madre , Linfocitos T/inmunología , Animales , Astrocitos/inmunología , Modelos Animales de Enfermedad , Antígenos de Histocompatibilidad Clase I , Antígenos de Histocompatibilidad Clase II , Humanos , Neuronas/inmunología , Ratas , Ratas Sprague-Dawley , Traumatismos de la Médula Espinal , Células Madre/inmunología , Trasplante Heterólogo/inmunología , Trasplante Homólogo/inmunología

RESUMEN

During the last decade, the interest in stem and progenitor cells, and their applications in spinal cord injuries have steadily increased. However, little is known about proliferation and cell death mechanisms in these cells after transplantation to the spinal cord. The aim of the present project was to study cell turn-over, i.e. total cell number, with time course of proliferation and cell death, in human neural precursor cells (NPCs) after transplantation to the injured rat spinal cord. Immunodeficient rats were subjected to lateral clip compression injuries, transplanted with neurospheres of human forebrain-derived NPCs two weeks after lesion, and sacrificed after 6 h, 1, 3, 10, or 21 days. Cell death was assessed by quantifying human cells immunoreactive for active caspase-3 and calpain 1-dependent fodrin breakdown products (FBDP). The results showed that after an initial drop, the number of implanted cells increased over time after transplantation. Cell proliferation was substantial, with 34% of human cells being immunoreactive for proliferating cell nuclear antigen at 6 h, but which declined over the next few days. The fractions of caspase-3-, and FBDP-immunoreactive cells were remarkably low, together representing 18% of all human cells at 6 h, and rapidly decreasing the next few days. Our results show that already 10 days after spinal cord transplantation of human NPCs as intact neurospheres, the number of human cells exceeded the initially implanted, which was the result of marked cell proliferation in combination with a low rate of apoptotic and non-apoptotic cell death taking place early after transplantation.

Asunto(s)

Neuronas/citología , Traumatismos de la Médula Espinal/cirugía , Trasplante de Células Madre , Células Madre/citología , Animales , Apoptosis/fisiología , Proliferación Celular , Femenino , Humanos , Inmunohistoquímica , Etiquetado Corte-Fin in Situ , Ratas , Ratas Desnudas

RESUMEN

OBJECTIVE: To perform an evidence-based review of the literature on neuroimaging techniques utilized in spinal cord injury clinical practice and research. METHODS: A search of the medical literature for articles on specific neuroimaging techniques used in SCI resulted in 2,302 published reports. Review at the abstract and full report level yielded 99 clinical and preclinical articles that were evaluated in detail. Sixty nine were clinical research studies subjected to quality of evidence grading. Twenty-three articles were drawn from the pre-clinical animal model literature and used for supportive evidence. Seven review articles were included to add an element of previous syntheses of current thinking on neuroimaging topics to the committee process (the review articles were not graded for quality of evidence). A list of clinical and research questions that might be answered on a variety of neuroimaging topics was created for use in article review. Recommendations on the use of neuroimaging in spinal cord injury treatment and research were made based on the quality of evidence. RESULTS: Of the 69 original clinical research articles covering a range of neuroimaging questions, only one was judged to provide Class I evidence, 22 provided Class II evidence, 17 Class III evidence, and 29 Class IV evidence. RECOMMENDATIONS: MRI should be used as the imaging modality of choice for evaluation of the spinal cord after injury. CT and plain radiography should be used to assess the bony anatomy of the spine in patients with SCI. MRI may be used to identify the location of spinal cord injury. MRI may be used to demonstrate the degree of spinal cord compression after SCI. MRI findings of parenchymal hemorrhage/ contusion, edema, and spinal cord disruption in acute and subacute SCI may contribute to the understanding of severity of injury and prognosis for neurological improvement. MRI-Diffusion Weighted Imaging may be useful in quantifying the extent of axonal loss after spinal cord injury. Functional MRI may be useful in measuring the anatomic functional/metabolic correlates of sensory-motor activities in persons with SCI. MR Spectroscopy may be used to measure the biochemical characteristics of the brain and spinal cord following SCI. Intraoperative Spinal Sonography may be used to identify spinal and spinal cord anatomy and gross pathology during surgical procedures. Further research in these areas is warranted to improve the strength of evidence supporting the use of neuroimaging modalities. Positron Emission Tomography may be used to assess metabolic activity of CNS tissue (brain and spinal cord) in patients with SCI.

Asunto(s)

Traumatismos de la Médula Espinal/diagnóstico , Ecoencefalografía , Humanos , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética , Espectroscopía de Resonancia Magnética , Tomografía de Emisión de Positrones

RESUMEN

There is heterogeneity in neural stem and progenitor cell characteristics depending on their species and regional origin. In search for potent in vitro-expanded human neural precursor cells and cell therapy methods to repair the injured human spinal cord, the possible influence exerted by intrinsic cellular heterogeneity has to be considered. Data available on in vitro-expanded human spinal cord-derived cells are sparse and it has previously been difficult to establish long-term neurosphere cultures showing multipotentiality. In the present paper, human spinal cord-derived neurospheres were cultured in the presence of EGF, bFGF and CNTF for up to 25 passages (>350 days) in vitro. In contrast to the human first trimester subcortical forebrain, spinal cord tissue>9.5 weeks of gestation could not serve as a source for long-term neurosphere cultures under the present conditions. After withdrawal of mitogens, cultured neurospheres (at 18 passages) gave rise to cells with neuronal, astrocytic and oligodendrocytic phenotypes in vitro. After transplantation of human spinal cord-derived neurospheres to the lesioned spinal cord of immuno-deficient adult rats, large numbers of cells survived at least up to 6 weeks, expressing neuronal and astrocytic phenotypes. These results demonstrate that it is possible to expand and maintain multipotent human spinal cord-derived neurospheres in vitro for extended time-periods and that they have promising in vivo potential after engraftment to the injured spinal cord.

Asunto(s)

Trasplante de Tejido Fetal/fisiología , Supervivencia de Injerto/fisiología , Neuronas/trasplante , Esferoides Celulares/trasplante , Traumatismos de la Médula Espinal/cirugía , Animales , Técnicas de Cultivo de Célula , Diferenciación Celular/fisiología , Células Cultivadas , Femenino , Células Madre Fetales/citología , Células Madre Fetales/trasplante , Trasplante de Tejido Fetal/métodos , Estudios de Seguimiento , Humanos , Inmunohistoquímica , Células Madre Multipotentes/citología , Células Madre Multipotentes/trasplante , Neuroglía/citología , Neuroglía/trasplante , Neuronas/citología , Prosencéfalo/citología , Prosencéfalo/embriología , Prosencéfalo/trasplante , Ratas , Ratas Desnudas , Esferoides Celulares/citología , Médula Espinal/citología , Médula Espinal/embriología , Médula Espinal/trasplante , Trasplante de Células Madre/métodos , Trasplante Heterólogo

RESUMEN

Human cytomegalovirus (HCMV) is the most common cause of congenital infections in developed countries, with an incidence varying between 0.5-2.2%. Such infection may be the consequence of either a primary infection or reactivation of a latent infection in the mother and the outcome may vary from asymptomatic to severe brain disorders. Moreover, infants that are asymptomatic at the time of birth may still develop neurologic sequelae at a later age. Our hypothesis is that infection of stem cells of the central nervous system by HCMV alters the proliferation, differentiation or migration of these cells, and thereby gives rise to the brain abnormalities observed. We show that infection of human neural precursor cells (NPCs) with the laboratory strain Towne or the clinical isolate TB40 of HCMV suppresses the differentiation of these cells into astrocytes even at an multiplicity of infection (MOI) as low as 0.1 (by 33% and 67%, respectively). This inhibition required active viral replication and the expression of late HCMV proteins. Infection as late as 24 hr after the onset of differentiation, but not after 72 hr, also prevented the maturation of infected cultures. Furthermore, in cultures infected with TB40 (at an MOI of 1), approximately 54% of the cells were apoptotic and cell proliferation was significantly attenuated. Clearly, HCMV can reduce the capacity of NPCs to differentiate into astrocytes and this effect may provide part of the explanation for the abnormalities in brain development associated with congenital HCMV infection.

Asunto(s)

Astrocitos/citología , Diferenciación Celular/efectos de los fármacos , Citomegalovirus/fisiología , Prosencéfalo/embriología , Proteínas Virales/farmacología , Aborto Inducido , Apoptosis/efectos de los fármacos , Astrocitos/efectos de los fármacos , Astrocitos/fisiología , Infecciones por Citomegalovirus/embriología , Infecciones por Citomegalovirus/transmisión , Femenino , Citometría de Flujo , Humanos , Embarazo , Prosencéfalo/citología , Prosencéfalo/efectos de los fármacos , Prosencéfalo/virología