Spinal cord injury in the rat

Versatile subtypes of pericytes and their roles in spinal cord injury repair, bone development and repair

Vascular regeneration is a challenging topic in tissue repair. As one of the important components of the neurovascular unit (NVU), pericytes play an essential role in the maintenance of the vascular network of the spinal cord. To date, subtypes of pericytes have been identified by various markers, namely the PDGFR-β, Desmin, CD146, and NG2, each of which is involved with spinal cord injury (SCI) repair. In addition, pericytes may act as a stem cell source that is important for bone development and regeneration, whilst specific subtypes of pericyte could facilitate bone fracture and defect repair. One of the major challenges of pericyte biology is to determine the specific markers that would clearly distinguish the different subtypes of pericytes, and to develop efficient approaches to isolate and propagate pericytes. In this review, we discuss the biology and roles of pericytes, their markers for identification, and cell differentiation capacity with a focus on the potential application in the treatment of SCI and bone diseases in orthopedics.

AAV2-mediated and hypoxia response element-directed expression of bFGF in neural stem cells showed therapeutic effects on spinal cord injury in rats

Neural stem cell (NSCs) transplantation has been one of the hot topics in the repair of spinal cord injury (SCI). Fibroblast growth factor (FGF) is considered a promising nerve injury therapy after SCI. However, owing to a hostile hypoxia condition in SCI, there remains a challenging issue in implementing these tactics to repair SCI. In this report, we used adeno-associated virus 2 (AAV2), a prototype AAV used in clinical trials for human neuron disorders, basic FGF (bFGF) gene under the regulation of hypoxia response element (HRE) was constructed and transduced into NSCs to yield AAV2-5HRE-bFGF-NSCs. Our results showed that its treatment yielded temporally increased expression of bFGF in SCI, and improved scores of functional recovery after SCI compared to vehicle control (AAV2-5HRE-NSCs) based on the analyses of the inclined plane test, Basso-Beattie-Bresnahan (BBB) scale and footprint analysis. Mechanistic studies showed that AAV2-5HRE-bFGF-NSCs treatment increased the expression of neuron-specific neuronal nuclei protein (NeuN), neuromodulin GAP43, and neurofilament protein NF200 while decreased the expression of glial fibrillary acidic protein (GFAP) as compared to the control group. Further, the expressions of autophagy-associated proteins LC3-II and Beclin 1 were decreased, whereas the expression of P62 protein was increased in AAV2-5HRE-bFGF-NSCs treatment group. Taken together, our data indicate that AAV2-5HRE-bFGF-NSCs treatment improved the recovery of SCI rats, which is accompanied by evidence of nerve regeneration, and inhibition of SCI-induced glial scar formation and cell autophagy. Thus, this study represents a step forward towards the potential use of AAV2-5HRE-bFGF-NSCs for future clinical trials of SCI repair.

Strategies for Oligodendrocyte and Myelin Repair in Traumatic CNS Injury

A major consequence of traumatic brain and spinal cord injury is the loss of the myelin sheath, a cholesterol-rich layer of insulation that wraps around axons of the nervous system. In the central nervous system (CNS), myelin is produced and maintained by oligodendrocytes. Damage to the CNS may result in oligodendrocyte cell death and subsequent loss of myelin, which can have serious consequences for functional recovery. Demyelination impairs neuronal function by decelerating signal transmission along the axon and has been implicated in many neurodegenerative diseases. After a traumatic injury, mechanisms of endogenous remyelination in the CNS are limited and often fail, for reasons that remain poorly understood. One area of research focuses on enhancing this endogenous response. Existing techniques include the use of small molecules, RNA interference (RNAi), and monoclonal antibodies that target specific signaling components of myelination for recovery. Cell-based replacement strategies geared towards replenishing oligodendrocytes and their progenitors have been utilized by several groups in the last decade as well. In this review article, we discuss the effects of traumatic injury on oligodendrocytes in the CNS, the lack of endogenous remyelination, translational studies in rodent models promoting remyelination, and finally human clinical studies on remyelination in the CNS after injury.

Tau Pathology Triggered by Spinal Cord Injury Can Play a Critical Role in the Neurotrauma Development

Traumatic spinal cord injury (SCI) can result in substantial neurological impairment along with significant emotional and psychological distress. It is clear that there is profound neurodegeneration upon SCI, gradually spread to other spinal cord regions and brain areas. Despite extensive considerations, it remains uncertain how pathogenicity diffuses in the cord. It has been reported that tau protein abnormal hyperphosphorylation plays a central role in neurodegeneration triggered by traumatic brain injury (TBI). Tau is a microtubule-associated protein, heavily implicated in neurodegenerative diseases. Importantly, tau pathology spreads in a traumatic brain in a timely manner. In particular, we have recently demonstrated that phosphorylated tau at Thr231 exists in two distinct cis and trans conformations, in which that cis P-tau is extremely neurotoxic, has a prion nature, and spreads to various brain areas and cerebrospinal fluid (CSF) upon trauma. On the other hand, tau pathology, in particular hyperphosphorylation at Thr231, has been observed upon SCI. Taken these together, we conclude that cis pT231-tau may accumulate and spread in the spinal cord as well as CSF and diffuse tau pathology in the central nervous system (CNS). Moreover, antibody against cis P-tau can target intracellular cis P-tau and protect pathology spreading. Thus, considering cis P-tau as a driver of tau pathology and neurodegeneration upon SCI would open new windows toward understanding the disease development and early biomarkers. Furthermore, it would help us develop effective therapies for SCI patients.

Effects of combined treatment of minocycline and methylprednisolone on the expression of tumor necrosis factor alpha and interleukine-6 in experimental spinal cord injury: a light and electron microscopic study

Spinal cord injury (SCI) is an important health problem, and there is no universal treatment protocol for it today. Following SCI pro-inflammatory mediators such as tumor necrosis factor- alpha (TNF-α) and interleukin-6 (IL-6) increase at the lesion site and play important roles in secondary tissue damage. Methylprednisolone (MP) is a glucocorticoid, and minocycline is a tetracycline-derived antibiotic both with neuroprotective effects on central nervous system trauma. However, there are limited studies on their effects on SCI. In this study, we aimed to evaluate effects of MP+minocycline combined treatment on cellular distribution and localization of TNF-α And IL-6 after SCI. Eighty Wistar rats were divided into three main groups as the intact control group, sham operation group, and experimental control group that received spinal cord compression injury. Following the injury, the experimental control group was subdivided into four groups as control, methylprednisolone treatment, minocycline treatment and, MP+minocycline combined treatment groups. Tissue samples were obtained from all groups at 24 hours and 72 hours after the injury. We found a significant decrease in TNF-α And IL-6 expressions in combined treatment group at 24 hours after injury. Also, there was a significant decrease in MDA and increase in SOD levels in this group. Furthermore, decreased lipid peroxidation and neuronal and glial cell death were also observed in combined treatment group. These results suggest that MP+minocycline combined treatment promotes functional recovery and, it should be considered as an effective treatment protocol following SCI.

Protective effect of Oxymatrine against acute spinal cord injury in rats via modulating oxidative stress, inflammation and apoptosis

The present study was performed to examine the effect of oxymatrine (OMT) on motor functions and histopathologic changes after spinal cord injury and the mechanism underlying its neuroprotective effects. Results suggested that, OMT causes regain of lost motor function near to normal via attenuating oxidative stress, inflammatory response and cellular apoptosis. These observations were further supported by histological examination of spinal cord of rats. It also showed to regulate pro-inflammatory cytokines, Bcl2 family proteins and reduces the level of toll like receptor (TLR-4) and nuclear factor-kappa B (NF-ĸB) in concentration dependent manner. The mitogen-activated protein kinase (MAPK) pathway was also regulated by OMT after SCI. It has been suggested that, OMT promotes the recovery of motor function after SCI in rats via multiple mechanism, and this effect may be related to its anti-oxidant, anti-inflammatory and anti-apoptotic effects.

VDAC1 is essential for neurite maintenance and the inhibition of its oligomerization protects spinal cord from demyelination and facilitates locomotor function recovery after spinal cord injury

During the progression of the neurodegenerative process, mitochondria participates in several intercellular signaling pathways. Voltage-dependent anion-selective channel 1 (VDAC1) is a mitochondrial porin involved in the cellular metabolism and apoptosis intrinsic pathway in many neuropathological processes. In spinal cord injury (SCI), after the primary cell death, a secondary response that comprises the release of pro-inflammatory molecules triggers apoptosis, inflammation, and demyelination, often leading to the loss of motor functions. Here, we investigated the functional role of VDAC1 in the neurodegeneration triggered by SCI. We first determined that in vitro targeted ablation of VDAC1 by specific morpholino antisense nucleotides (MOs) clearly promotes neurite retraction, whereas a pharmacological blocker of VDAC1 oligomerization (4, 4′-diisothiocyanatostilbene-2, 2′-disulfonic acid, DIDS), does not cause this effect. We next determined that, after SCI, VDAC1 undergoes conformational changes, including oligomerization and N-terminal exposition, which are important steps in the triggering of apoptotic signaling. Considering this, we investigated the effects of DIDS in vivo application after SCI. Interestingly, blockade of VDAC1 oligomerization decreases the number of apoptotic cells without interfering in the neuroinflammatory response. DIDS attenuates the massive oligodendrocyte cell death, subserving undisputable motor function recovery. Taken together, our results suggest that the prevention of VDAC1 oligomerization might be beneficial for the clinical treatment of SCI.

An Accurate Method for Histological Determination of Neural Tissue Loss/Sparing after Compression-Induced Spinal Cord Injury with Optimal Reproducibility

In addition to behavioral testing, the efficacy of neuroprotective therapies applied after spinal cord injury (SCI) is commonly evaluated by means of histological quantification of spared neural tissue. The primary insult itself, but mainly the pathological processes of secondary injury are the underlying causes of spinal tissue degeneration, the extent of which depends on the injury severity and post-injury time. Under-estimation of tissue loss due to spinal cord shrinkage and subjective evaluation (impeding reproducibility) are substantial factors that negatively affect the final results. Moreover, processing large numbers of stained spinal cord sections is very time-consuming. To overcome the problem, our new quantification approach combines a modified method for predicting the cross-sectional area at the lesion site with semi-automatic measurement of spared neural tissue and cystic cavities, using freely accessible National Institutes of Health (NIH) ImageJ software, with a Java-based image processing program. Based on the histological parameters measured after differing compression-induced SCI and correlated with behavioral outcomes, we can conclude that our new method is relatively fast, accurate, and optimally reproducible.

Attenuating the DNA damage response to double-strand breaks restores function in models of CNS neurodegeneration

DNA double-strand breaks are a feature of many acute and long-term neurological disorders, including neurodegeneration, following neurotrauma and after stroke. Persistent activation of the DNA damage response in response to double-strand breaks contributes to neural dysfunction and pathology as it can force post-mitotic neurons to re-enter the cell cycle leading to senescence or apoptosis. Mature, non-dividing neurons may tolerate low levels of DNA damage, in which case muting the DNA damage response might be neuroprotective. Here, we show that attenuating the DNA damage response by targeting the meiotic recombination 11, Rad50, Nijmegen breakage syndrome 1 complex, which is involved in double-strand break recognition, is neuroprotective in three neurodegeneration models in Drosophila and prevents Aβ_1-42-induced loss of synapses in embryonic hippocampal neurons. Attenuating the DNA damage response after optic nerve injury is also neuroprotective to retinal ganglion cells and promotes dramatic regeneration of their neurites both in vitro and in vivo. Dorsal root ganglion neurons similarly regenerate when the DNA damage response is targeted in vitro and in vivo and this strategy also induces significant restoration of lost function after spinal cord injury. We conclude that muting the DNA damage response in the nervous system is neuroprotective in multiple neurological disorders. Our results point to new therapies to maintain or repair the nervous system.

Neuroprotection, Recovery of Function and Endogenous Neurogenesis in Traumatic Spinal Cord Injury Following Transplantation of Activated Adipose Tissue

Spinal cord injury (SCI) is a devastating disease, which leads to paralysis and is associated to substantially high costs for the individual and society. At present, no effective therapies are available. Here, the use of mechanically-activated lipoaspirate adipose tissue (MALS) in a murine experimental model of SCI is presented. Our results show that, following acute intraspinal MALS transplantation, there is an engraftment at injury site with the acute powerful inhibition of the posttraumatic inflammatory response, followed by a significant progressive improvement in recovery of function. This is accompanied by spinal cord tissue preservation at the lesion site with the promotion of endogenous neurogenesis as indicated by the significant increase of Nestin-positive cells in perilesional areas. Cells originated from MALS infiltrate profoundly the recipient cord, while the extra-dural fat transplant is gradually impoverished in stromal cells. Altogether, these novel results suggest the potential of MALS application in the promotion of recovery in SCI.

The Efficacy and Safety of Mesenchymal Stem Cell Transplantation for Spinal Cord Injury Patients: A Meta-Analysis and Systematic Review

Spinal cord injury (SCI) is a devastating disease, with a high rate of disability. In this meta-analysis, we aimed to comprehensively assess the efficacy and safety of mesenchymal stem cells (MSCs) in treating clinical SCI patients. We systematically searched the PUBMED, EMBASE, Chinese Biomedical (CBM), Web of Science and Cochrane databases using the strategy of combination of free-text words and MeSH terms. The indicators of the American Spinal Injury Association (ASIA) impairment scale (AIS)-grading improvement rate and adverse effects were displayed with an overall relative risk (RR). For the continuous variables of the ASIA motor score, light-touch score, pinprick score, activities of daily living (ADL) score, and residual urine volume, we used odds ratio (OR) to analyze the data. Eleven studies comprising 499 patients meeting all inclusion and exclusion criteria were included. No serious heterogeneity or publication bias was observed across each study. The results showed that significant improvements of total AIS grade (RR: 3.70; P < 0.001), AIS grade A (RR: 3.57; P < 0.001), ASIA sensory score (OR: 8.63; P < 0.001) and reduction of residual urine volume (OR: -36.37; P = 0.03) were observed in experimental group compared with control group. However, no significant differences of motor score (OR: 1.37, P = 0.19) and ADL score (OR: 2.61, P = 0.27) were observed between experimental and control groups. In addition, there were no serious and permanent adverse effects after cell transplantation. Cell transplantation with MSCs is effective and safe in improving the sensory and bladder functions of SCI patients.

Effect of transplantation of olfactory ensheathing cell conditioned medium induced bone marrow stromal cells on rats with spinal cord injury

Spinal cord injury is a serious threat to human health and various techniques have been deployed to ameliorate or cure its effects. Stem cells transplantation is one of the promising methods. The primary aim of the present study was to investigate the effect of the transplantation of olfactory ensheathing cell (OEC) conditioned medium-induced bone marrow stromal cells (BMSCs) on spinal cord injury. Rat spinal cord compression injury animal models were generated, and the rats divided into the following three groups: Group A, (control) Dulbecco's modified Eagle's medium-treated group; group B, normal BMSC-treated group; group C, OEC conditioned medium-induced BMSC-treated group. The animals were sacrificed at 2, 4 and 8 weeks following transplantation for hematoxylin and eosin staining, and fluorescence staining of neurofilament protein, growth associated protein-43 and neuron-specific nuclear protein. The cavity area of the spinal cord injury was significantly reduced at 2 and 4 weeks following transplantation in group C, and a significant difference between the Basso, Beattie and Bresnahan score in group C and groups A and B was observed. Regenerated nerve fibers were observed in groups B and C; however, a greater number of regenerated nerve fibers were observed in group C. BMSCs induced by OEC conditioned medium survived in vivo, significantly reduced the cavity area of spinal cord injury, promoted nerve fiber regeneration following spinal cord injury and facilitated recovery of motor function. The present study demonstrated a novel method to repair spinal cord injury by using induced BMSCs, with satisfactory results.

The effectiveness of the anti-CD11d treatment is reduced in rat models of spinal cord injury that produce significant levels of intraspinal hemorrhage

We have previously reported that administration of a CD11d monoclonal antibody (mAb) improves recovery in a clip-compression model of SCI. In this model the CD11d mAb reduces the infiltration of activated leukocytes into the injured spinal cord (as indicated by reduced intraspinal MPO). However not all anti-inflammatory strategies have reported beneficial results, suggesting that success of the CD11d mAb treatment may depend on the type or severity of the injury. We therefore tested the CD11d mAb treatment in a rat hemi-contusion model of cervical SCI. In contrast to its effects in the clip-compression model, the CD11d mAb treatment did not improve forelimb function nor did it significantly reduce MPO levels in the hemi-contused cord. To determine if the disparate results using the CD11d mAb were due to the biomechanical nature of the cord injury (compression SCI versus contusion SCI) or to the spinal level of the injury (12th thoracic level versus cervical) we further evaluated the CD11d mAb treatment after a T12 contusion SCI. In contrast to the T12 clip compression SCI, the CD11d mAb treatment did not improve locomotor recovery or significantly reduce MPO levels after T12 contusion SCI. Lesion analyses revealed increased levels of hemorrhage after contusion SCI compared to clip-compression SCI. SCI that is accompanied by increased intraspinal hemorrhage would be predicted to be refractory to the CD11d mAb therapy as this approach targets leukocyte diapedesis through the intact vasculature. These results suggest that the disparate results of the anti-CD11d treatment in contusion and clip-compression models of SCI are due to the different pathophysiological mechanisms that dominate these two types of spinal cord injuries.

Electro-acupuncture-modulated miR-214 prevents neuronal apoptosis by targeting Bax and inhibits sodium channel Nav1.3 expression in rats after spinal cord injury

Electro-acupuncture (EA) has been proven to contribute towards neurologic and functional recoveries in spinal cord injury (SCI), but the underlying mechanism remains largely unknown especially regarding the effects of preventing neuronal apoptosis and alleviating neuropathic pain involved in the development of EA. In this study, we evaluated the effect of EA treatment in an animal model of SCI using the Basso, Beattie, and Bresnahan (BBB) score method, lesion volume by cresyl violet staining and neuronal apoptosis by TUNEL staining. Our results showed that EA therapy improved functional recovery, and reduced tissue loss and neuronal apoptosis after SCI. Meanwhile, we found that proapoptotic proteins (cleaved-caspase-3, 9 and cleaved-PARP) were downregulated and antiapoptotic protein Bcl-2 was upregulated following EA. To further explore the antiapoptotic effect of EA treatment, we verified that a large set of microRNAs (miRNAs) expression were altered following EA treatment and the miR-214 was one of the miRNAs being most significantly upregulated. Importantly, we validated both apoptosis related protein Bax and pain related protein Nav1.3 as two functional targets of miR-214 in vitro and vivo. Furthermore, our data showed that EA attenuates SCI-induced Nav1.3 and Bax upregulation in injured spinal cord via upregulating miR-214. These results suggest that miR-214 played an important role after SCI in the process of EA therapy, and the miR-214 could become an attractive novel therapeutic target for the treatment of SCI.

Low-Level Laser Irradiation Improves Motor Recovery After Contusive Spinal Cord Injury in Rats

This study investigated the therapeutic effects of low-level laser irradiation (LLLI) on the recovery of motor function and its underlying mechanisms in rats with spinal cord injury (SCI). The spinal cord was contused at the T11 level using a New York University impactor. Thirty-eight rats were randomly divided into four groups: LLLI with 0.08 J, 0.4 J, 0.8 J, and sham. We transcutaneously applied at the lesion site of the spinal contusive rats 5 min after injury and then daily for 21 days. The Basso, Beattie and Bresnahan (BBB) locomotor scale and combined behavioral score (CBS) were used to evaluate motor function. The spinal segments of rostral and caudal from the lesion site, the epicenter, and L4-5 were collected from normal and the all groups at 7 days after SCI. The expression of tumor necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS) was compared across groups in all regions. In the present study, LLLI with 0.4 J and 0.8 J led to a significant improvement in motor function compared to sham LLLI, which significantly decreased TNF-α expression at the lesion epicenter and reduced iNOS expression in the caudal segment for all LLLI groups and in the L4-5 segments for the 0.4 J and 0.8 J groups when compared to sham LLLI group. Our results demonstrate that transcutaneous LLLI modulate inflammatory mediators to enhance motor function recovery after SCI. Thus, LLLI in acute phase after SCI might have therapeutic potential for neuroprotection and restoration of motor function following SCI.

Combination of melatonin and Wnt-4 promotes neural cell differentiation in bovine amniotic epithelial cells and recovery from spinal cord injury

Although melatonin has been shown to exhibit a wide variety of biological functions, its effects on promoting differentiation of neural cells remain unknown. Wnt signaling mediates major developmental processes during embryogenesis and regulates maintenance, self-renewal, and differentiation of adult mammalian stem cells. However, the role of the noncanonical Wnt pathway during neurogenesis remains poorly understood. In this study, the amniotic epithelial cells ( AECs) were isolated from bovine amnion and incubated with various melatonin concentrations (0.01, 0.1, 1, 10, or 100 μm) and 5 × 10(-5) m all-trans retinoic acid (RA) for screening optimum culture medium of neural differentiation, compared with each groups, 1 μm melatonin and 5 × 10(-5) m RA were selected to induce neural differentiation of AECs, and then siMT1, siMT2, oWnt-4, and siWnt-4 were expressed in AECs to research role of these genes in neural differentiation. Efficiency of neural differentiation was evaluated after expressed above genes using flow cytometry. Cell function of neural cells was demonstrated in vivo using spinal cord injury model after cell transplantation, and damage repair of spinal cord was assessed using cell tracking and Basso, Beattie, Bresnahan Locomotor Rating Scale scores. Results demonstrated that melatonin stimulated melatonin receptor 1, which subsequently increased bovine amniotic epithelial cell vitality and promoted differentiation into neural cells. This took place through cooperation with Wnt-4. Additionally, following cotreatment with melatonin and Wnt-4, neurogenesis gene expression was significantly altered. Furthermore, single inhibition of melatonin receptor 1 or Wnt-4 expression decreased expression of neurogenesis-related genes, and bovine amniotic epithelial cell-derived neural cells were successfully colonized into injured spinal cord, which suggested participation in tissue repair.

The relative contribution of edema and hemorrhage to raised intrathecal pressure after traumatic spinal cord injury

Raised intrathecal pressure (ITP) after traumatic spinal cord injury (SCI) is a critically important aspect of injury development that may result in significantly greater tissue damage and worsened functional outcome. Raised ITP is caused by the accumulation of blood and/or water (edema), and while their occurrence after traumatic SCI has been well established, the relative contribution of both processes to the development of ITP after SCI has not yet been determined. Accordingly, the current study investigates the temporal profile of raised ITP after traumatic SCI in relation to both hemorrhage and edema development. A closed balloon compression injury was induced at T10 in New Zealand White rabbits. Animals were thereafter assessed for spinal water content (edema), ITP, lesion and hemorrhage volume, and albumin immunoreactivity from 5 h to 1 week post-SCI. Early increases in ITP at 5 h post-injury were associated with significant increases in blood volume. ITP, however, was maximal at 3 days post-SCI, at which time there was an associated significant increase in edema that persisted for 1 week. We conclude that raised ITP after traumatic SCI is initially driven by volumetric increases in hemorrhage, while edema becomes the primary driver of ITP at 3 days post-injury.

Panax ginseng Improves Functional Recovery after Contusive Spinal Cord Injury by Regulating the Inflammatory Response in Rats: An In Vivo Study

Spinal cord injury (SCI) results in permanent loss of motor function below the injured site. Neuroinflammatory reaction following SCI can aggravate neural injury and functional impairment. Ginseng is well known to possess anti-inflammatory effects. The present study investigated the neuroprotective effects of Panax ginseng C.A. Mayer (P. ginseng) after SCI. A spinal contusion was made at the T11-12 spinal cord in adult male Sprague-Dawley rats (n = 47) using the NYU impactor. Motor function was assessed using the Basso-Beattie-Bresnahan (BBB) score in P. ginseng (0.1, 0.5, 1, 3, and 5 mg/kg) or vehicle (saline) treated after SCI. We also assessed the protein expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) at the lesion site by western blot and then measured the cavity area using luxol fast blue/cresyl violet staining. P. ginseng treated group in SCI showed a significant improvement in locomotor function after the injury. The protein expression of COX-2 and iNOS at the lesion site and the cavity area were decreased following SCI by P. ginseng treatment. These results suggest that P. ginseng may improve the recovery of motor function after SCI which provides neuroprotection by alleviating posttraumatic inflammatory responses.

Pathogenetic Mechanisms of Neurogenic Pulmonary Edema

Neurogenic pulmonary edema (NPE) is a life-threatening complication of central nervous system (CNS) injuries. This review summarizes current knowledge about NPE etiology and pathophysiology with an emphasis on its experimental models, including our spinal cord compression model. NPE may develop as a result of activation of specific CNS trigger zones located in the brainstem, leading to a rapid sympathetic discharge, rise in systemic blood pressure, baroreflex-induced bradycardia, and enhanced venous return resulting in pulmonary vascular congestion characterized by interstitial edema, intra-alveolar accumulation of transudate, and intra-alveolar hemorrhages. The potential etiological role of neurotransmitter changes in NPE trigger zones leading to enhanced sympathetic nerve activity is discussed. Degree of anesthesia is a crucial determinant for the extent of NPE development in experimental models because of its influence on sympathetic nervous system activity. Sympathetic hyperactivity is based on the major activation of either ascending spinal pathways by spinal cord injury or NPE trigger zones by increased intracranial pressure. Attenuation of sympathetic nerve activity or abolition of reflex bradycardia completely prevent NPE development in our experimental model. Suggestions for future research into NPE pathogenesis as well as therapeutic potential of particular drugs and interventions are discussed.

Regulation of gene expression in rats with spinal cord injury based on microarray data

The present study aimed to investigate the molecular mechanisms of spinal cord injury (SCI) in rats. First, the differentially expressed genes (DGEs) were screened based on GSE45006 microarray data downloaded from Gene Expression Omnibus using the significant analysis of microarray (SAM) method. Screening was performed for DEGs which were negatively or possibly correlated with time and subsequently subjected to gene ontology (GO) functional annotation. Furthermore, pathway enrichment analysis using the Kyoto Encyclopedia of Genes and Genomes was also performed. In addition, a protein-protein interaction (PPI) network was constructed using the Search Tool for the Retrieval of Interacting Genes/Proteins database. Finally, GeneCodis was used to seek transcription factors and microRNAs that are involved in the regulation of DEGs. A total of 806 DEGs were upregulated and 549 DEGs were downregulated in the rats with SCI. Cholesterol metabolism-associated genes (e.g. HMGCS1, FDFT1 and IDI1) were negatively correlated with time, while injury genes (e.g. SERPING1, C1S and RAB27A) were positively correlated with time after SCI. PCNA, MCM2, JUN and SNAP25 were the hub proteins of the PPI network. The transcription factors LEF1 and SP1 were observed to be associated with the regulation of two DEGs that were involved in the cholesterol-associated metabolism as well as injury responses. A number of microRNAs (e.g. miR210, miR-487b and miR-16) were observed to target cholesterol metabolism-associated DGEs. The hub genes PCNA, MCM2, JUN and SNAP25 presumably have critical roles in rats with SCI, and the transcription factors LEF1 and SP1 may be important for the regulation of cholesterol metabolism and injury responses following SCI.

The prognostic value of cerebrospinal fluid characteristics in dogs without deep pain perception due to thoracolumbar disc herniation

Providing a pre-operative prognosis for dogs presented with absent deep pain perception (DPP) is extremely challenging, as the overall recovery rates widely vary. This study assesses the possible correlation between the severity of spinal cord injury and CSF cytology in 31 paraplegic dogs presented with absent DPP due to acute thoracolumbar intervertebral disc herniation (TL-IVDH). All dogs underwent surgical decompression immediately following diagnosis. CSF TNCC, macrophage percentage and macrophage to monocyte (MΦ:M) ratio were significantly higher in dogs that failed to regain DPP within 10 days post-operatively and in dogs that failed to regain ambulation at the end of the study period (P< 0.05). MΦ:M of 0.73 and higher corresponded to a sensitivity of 54% and specificity of 100% for prediction of a negative long-term outcome. CSF TNCC, macrophage percentage and MΦ:M ratio effectively predicted regaining DPP and the long-term outcome in dogs that lost DPP due to acute TL-IVDH.

Neural stem cell-conditioned medium protects neurons and promotes propriospinal neurons relay neural circuit reconnection after spinal cord injury

Human fetal neural stem cells (hNSCs) are used to treat a variety of neurological disorders involving spinal cord injury (SCI). Although their mechanism of action has been attributed to cell substitution, we examined the possibility that NSCs may have neuroprotective activities. The present article studied the action of hNSCs on protecting neurons and promoting corticospinal tract (CST) axon regeneration after SCI. hNSCs were isolated from the cortical tissue of spontaneously aborted human fetuses. The cells were removed from the NSC culture medium to acquire NSCM, thus excluding the effect of cell substitution. Continuous administration of the NSCM after the SCI resulted in extensive growth of the CST in the cervical region and more than tripled the formation of synaptic contacts between CST collaterals and propriospinal interneurons that project from the cervical level of the spinal cord to the lumbar level. NSCM reduced the number of caspase 3-positive apoptotic profiles at 7 days and protected against loss of the neurons 6 weeks after injury. NSCM promoted locomotor recovery with a five-point improvement on the BBB scale in adult rats. Thus, hNSCs help to set up a contour neural circuit via secretory factors, which may be the mechanism for their action in SCI rats. This manuscript is published as part of the International Association of Neurorestoratology (IANR) special issue of Cell Transplantation.

Exogenous adult postmortem neural precursors attenuate secondary degeneration and promote myelin sparing and functional recovery following experimental spinal cord injury

Spinal cord injury (SCI) is a debilitating clinical condition, characterized by a complex of neurological dysfunctions. Neural stem cells from the subventricular zone of the forebrain have been considered a potential tool for cell replacement therapies. We recently isolated a subclass of neural progenitors from the cadaver of mouse donors. These cells, named postmortem neural precursor cells (PM-NPCs), express both erythropoietin (EPO) and its receptor. Their EPO-dependent differentiation abilities produce a significantly higher percentage of neurons than regular NSCs. The cholinergic yield is also higher. The aim of the present study was to evaluate the potential repair properties of PM-NPCs in a mouse model of traumatic SCI. Labeled PM-NPCs were administered intravenously; then the functional recovery and the fate of transplanted cells were studied. Animals transplanted with PM-NPCs showed a remarkable improved recovery of hindlimb function that was evaluated up to 90 days after lesion. This was accompanied by reduced myelin loss, counteraction of the invasion of the lesion site by the inflammatory cells, and an attenuation of secondary degeneration. PM-NPCs migrate mostly at the injury site, where they survive at a significantly higher extent than classical NSCs. These cells accumulate at the edges of the lesion, where a reach neuropile is formed by MAP2- and β-tubulin III-positive transplanted cells that are also mostly labeled by anti-ChAT antibodies.

Intraspinal transplantation of motoneuron-like cell combined with delivery of polymer-based glial cell line-derived neurotrophic factor for repair of spinal cord contusion injury

To evaluate the effects of glial cell line-derived neurotrophic factor transplantation combined with adipose-derived stem cells-transdifferentiated motoneuron delivery on spinal cord contusion injury, we developed rat models of spinal cord contusion injury, 7 days later, injected adipose-derived stem cells-transdifferentiated motoneurons into the epicenter, rostral and caudal regions of the impact site and simultaneously transplanted glial cell line-derived neurotrophic factor-gelfoam complex into the myelin sheath. Motoneuron-like cell transplantation combined with glial cell line-derived neurotrophic factor delivery reduced cavity formations and increased cell density in the transplantation site. The combined therapy exhibited superior promoting effects on recovery of motor function to transplantation of glial cell line-derived neurotrophic factor, adipose-derived stem cells or motoneurons alone. These findings suggest that motoneuron-like cell transplantation combined with glial cell line-derived neurotrophic factor delivery holds a great promise for repair of spinal cord injury.

Rat hair follicle stem cells differentiate and promote recovery following spinal cord injury

Emerging studies of treating spinal cord injury (SCI) with adult stem cells led us to evaluate the effects of transplantation of hair follicle stem cells in rats with a compression-induced spinal cord lesion. Here, we proposed a hypothesis that rat hair follicle stem cell transplantation can promote the recovery of injured spinal cord. Compression-induced spinal cord injury was induced in Wistar rats in this study. The bulge area of the rat vibrissa follicles was isolated, cultivated and characterized with nestin as a stem cell marker. 5-Bromo-2'-deoxyuridine (BrdU) labeled bulge stem cells were transplanted into rats with spinal cord injury. Immunohistochemical staining results showed that some of the grafted cells could survive and differentiate into oligodendrocytes (receptor-interacting protein positive cells) and neuronal-like cells (βIII-tubulin positive cells) at 3 weeks after transplantation. In addition, recovery of hind limb locomotor function in spinal cord injury rats at 8 weeks following cell transplantation was assessed using the Basso, Beattie and Bresnahan (BBB) locomotor rating scale. The results demonstrate that the grafted hair follicle stem cells can survive for a long time period in vivo and differentiate into neuronal- and glial-like cells. These results suggest that hair follicle stem cells can promote the recovery of spinal cord injury.

Protective effects of glucosamine-kynurenic acid after compression-induced spinal cord injury in the rat

Kynurenic acid (KYNA), a metabolite of the essential amino acid L-tryptophan, is a broad spectrum antagonist of excitatory amino acid receptors, which have also anticonvulsant and neuroprotective properties. After spinal cord injury (SCI), excitotoxicity is considered to play a significant role in the processes of secondary tissue destruction in both grey and white matter of the spinal cord. In this study, we have tested the potential therapeutic effect of glucosamine-kynurenic acid, administered after experimental compression-induced SCI in the rat. Spinal application of glucosamine-kynurenic acid continually for 24 hr after experimental SCI resulted in improved motor function recovery, beginning from the first week of evaluation and continuing until the end of the study (4 weeks). After 4 weeks’ survival, quantitative morphometric analysis of the spinal cord showed that glucosamine-kynurenic acid treatment was associated with improved tissue preservation at the lesion site. These findings indicate that spinal application of glucosaminekynurenic acid is neuroprotective and improves the outcome even when administered after spinal trauma. Our results suggest that the treatments initiated in early posttraumatic period can alleviate secondary injury and improve the final outcome after SCI.

A CD11d monoclonal antibody treatment reduces tissue injury and improves neurological outcome after fluid percussion brain injury in rats

Traumatic brain injury (TBI) is an international health concern often resulting in chronic neurological abnormalities, including cognitive deficits, emotional disturbances, and motor impairments. An anti-CD11d monoclonal antibody that blocks the CD11d/CD18 integrin and vascular cell adhesion molecule (VCAM)-1 interaction following experimental spinal cord injury improves functional recovery, while reducing the intraspinal number of neutrophils and macrophages, oxidative activity, and tissue damage. Since the mechanisms of secondary injury in the brain and spinal cord are similar, we designed a study to evaluate fully the effects of anti-CD11d treatment after a moderate lateral fluid percussion TBI in the rat. Rats were treated at 2 h after TBI with either the anti-CD11d antibody or an isotype-matched control antibody 1B7, and both short (24- to 72-h) and long (4-week) recovery periods were examined. The anti-CD11d integrin treatment reduced neutrophil and macrophage levels in the injured brain, with concomitant reductions in lipid peroxidation, astrocyte activation, amyloid precursor protein accumulation, and neuronal loss. The reduced neuroinflammation seen in anti-CD11d-treated rats correlated with improved performance on a number of behavioral tests. At 24 h, the anti-CD11d group performed significantly better than the 1B7 controls on several water maze measures of spatial cognition. At 4 weeks post-injury the anti-CD11d-treated rats had better sensorimotor function as assessed by the beam task, and reduced anxiety-like behaviors, as evidenced by elevated-plus maze testing, compared to 1B7 controls. These findings suggest that neuroinflammation is associated with behavioral deficits after TBI, and that anti-CD11d antibody treatment is a viable strategy to improve neurological outcomes after TBI.

Spatial and temporal correlation in progressive degeneration of neurons and astrocytes in contusion-induced spinal cord injury

BACKGROUND

Traumatic spinal cord injury (SCI) causes acute neuronal death followed by delayed secondary neuronal damage. However, little is known about how microenvironment regulating cells such as microglia, astrocytes, and blood inflammatory cells behave in early SCI states and how they contribute to delayed neuronal death.

METHODS

We analyzed the behavior of neurons and microenvironment regulating cells using a contusion-induced SCI model, examining early (3-6 h) to late times (14 d) after the injury.

RESULTS

At the penumbra region close to the damaged core (P1) neurons and astrocytes underwent death in a similar spatial and temporal pattern: both neurons and astrocytes died in the medial and ventral regions of the gray matter between 12 to 24 h after SCI. Furthermore, mRNA and protein levels of transporters of glutamate (GLT-1) and potassium (Kir4.1), functional markers of astrocytes, decreased at about the times that delayed neuronal death occurred. However, at P1 region, ramified Iba-1+ resident microglia died earlier (3 to 6 h) than neurons (12 to 24 h), and at the penumbra region farther from the damaged core (P2), neurons were healthy where microglia were morphologically activated. In addition, round Iba-1/CD45-double positive monocyte-like cells appeared after neurons had died, and expressed phagocytic markers, including mannose receptors, but rarely expressed proinflammatory mediators.

CONCLUSION

Loss of astrocyte function may be more critical for delayed neuronal death than microglial activation and monocyte infiltration.

Early Blockade of TLRs MyD88-Dependent Pathway May Reduce Secondary Spinal Cord Injury in the Rats

To determine the role of toll-like receptors (TLRs) myeloid differentiation factor 88 (MyD88) dependent pathway in the spinal cord secondary injury, compression injury was made at T8 segment of the spinal cord in adult male Sprague-Dawley rats. Shown by RT-PCR, TLR4 mRNA in the spinal cord was quickly elevated after compression injury. Intramedullary injection of MyD88 inhibitory peptide (MIP) resulted in significant improvement in locomotor function recovery at various time points after surgery. Meanwhile, injury area, p38 phosphorylation, and proinflammation cytokines in the injured spinal cord were significantly reduced in MIP-treated animals, compared with control peptide (CP) group. These data suggest that TLRs MyD88-dependent pathway may play an important role in the development of secondary spinal cord injury, and inhibition of this pathway at early time after primary injury could effectively protect cells from inflammation and apoptosis and therefore improve the functional recovery.

Human spinal cord injury causes specific increases in surface expression of β integrins on leukocytes

Spinal cord injury (SCI) activates circulating leukocytes that migrate into the injured cord and bystander organs using adhesion molecule-mediated mechanisms. These cells cause oxidative damage, resulting in secondary injury to the spinal cord, as well as injury to bystander organs. This study was designed to examine, over a 6-h to 2-week period, changes in adhesion molecule surface expression on human peripheral leukocytes after SCI (9 subjects), using as controls 10 uninjured subjects and 6 general trauma patients (trauma controls, TC). Both the percentage of cells expressing a given adhesion molecule and the average level of its expression was quantified for both circulating neutrophils and monocytes. The percentage of neutrophils and monocytes expressing the selectin CD62L was unchanged in TC and SCI patients after injury compared to uninjured subjects. Concurrently, the amount of surface CD62L on neutrophils was decreased in SCI and TC subjects, and on monocytes after SCI. The percentage of neutrophils expressing α4 decreased in TC, but not in SCI, subjects. Likewise, the percentage of neutrophils and monocytes expressing CD11d decreased markedly in TC subjects, but not after SCI. In contrast, the mean surface expression of α4 and CD11d by neutrophils and monocytes increased after SCI compared with uninjured and TC subjects. The percentage of cells and surface expression of CD11b were similar in neutrophils of all three groups, whereas CD11b surface expression increased after SCI in monocytes. In summary, unlike changes found after general trauma, the proinflammatory stimulation induced by SCI increases the surface expression of adhesion molecules on circulating neutrophils and monocytes before they infiltrate the injured spinal cord and multiple organs of patients. Integrins may be excellent targets for anti-inflammatory treatment after human SCI.

CD11d Antibody Treatment Improves Recovery in Spinal Cord-Injured Mice

Acute administration of a monoclonal antibody (mAb) raised against the CD11d subunit of the leukocyte CD11d/CD18 integrin after spinal cord injury (SCI) in the rat greatly improves neurological outcomes. This has been chiefly attributed to the reduced infiltration of neutrophils into the injured spinal cord in treated rats. More recently, treating spinal cord-injured mice with a Ly-6G neutrophil-depleting antibody was demonstrated to impair neurological recovery. These disparate results could be due to different mechanisms of action utilized by the two antibodies, or due to differences in the inflammatory responses between mouse and rat that are triggered by SCI. To address whether the anti-CD11d treatment would be effective in mice, a CD11d mAb (205C) or a control mAb (1B7) was administered intravenously at 2, 24, and 48 h after an 8-g clip compression injury at the fourth thoracic spinal segment. The anti-CD11d treatment reduced neutrophil infiltration into the injured mouse spinal cord and was associated with increased white matter sparing and reductions in myeloperoxidase (MPO) activity, reactive oxygen species, lipid peroxidation, and scar formation. These improvements in the injured spinal cord microenvironment were accompanied by increased serotonin (5-HT) immunoreactivity below the level of the lesion and improved locomotor recovery. Our results with the 205C CD11d mAb treatment complement previous work using this anti-integrin treatment in a rat model of SCI.

Neurogenic Pulmonary Edema Induced by Spinal Cord Injury in Spontaneously Hypertensive and Dahl Salt Hypertensive Rats

Neurogenic pulmonary edema (NPE), which is induced by acute spinal cord compression (SCC) under the mild (1.5 %) isoflurane anesthesia, is highly dependent on baroreflex-mediated bradycardia because a deeper (3 %) isoflurane anesthesia or atropine pretreatment completely abolished bradycardia occurrence and NPE development in rats subjected to SCC. The aim of the present study was to evaluate whether hypertension-associated impairment of baroreflex sensitivity might exert some protection against NPE development in hypertensive animals. We therefore studied SCC-induced NPE development in two forms of experimental hypertension – spontaneously hypertensive rats (SHR) and salt hypertensive Dahl rats, which were reported to have reduced baroreflex sensitivity. SCC elicited NPE in both hypertensive models irrespective of their baroreflex sensitivity. It is evident that a moderate impairment of baroreflex sensitivity, which was demonstrated in salt hypertensive Dahl rats, does not exert sufficient protective effects against NPE development.

High-mobility group box-1 and its receptors contribute to proinflammatory response in the acute phase of spinal cord injury in rats

STUDY DESIGN

To examine the localization and expression of high-mobility group box-1 (HMGB-1) protein and its receptors after rat spinal cord injury.

OBJECTIVE

To elucidate the contribution of HMGB-1 and its receptors as potential candidates in a specific upstream pathway to the proinflammatory response leading to a cascade of secondary tissue damage after spinal cord injury.

SUMMARY OF BACKGROUND DATA

HMGB-1 was recently characterized as a key cytokine with a potential role in nucleosome formation and regulation of gene transcription. No studies have investigated the role of HMGB-1 in spinal cord injury.

METHODS

Injured thoracic spinal cord from 62 rats aged 8 to 12 weeks and spinal cord from 20 control rats were examined. HMGB-1 was localized by immunofluorescence staining, costaining with cell markers, and by immunoelectron microscopy. The expression of HMGB-1 and its receptors, receptor for advanced glycation end products (RAGE), toll-like receptor (TLR)2, and TLR4 were also examined by immunohistochemistry.

RESULTS

HMGB-1 expression appeared earlier than that of tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 in the spinal cord injury rats, with the HMGB-1 produced by both macrophages and neurons. HMGB-1 translocated from nucleus to cytoplasm in some neurons at an early stage after neural injury. Increased expression of HMGB-1, RAGE, and TLRs was observed after injury, and interaction of HMGB-1 with RAGE or TLRs, particularly in macrophage, was confirmed at 3 days after injury.

CONCLUSION

Our results demonstrated an earlier onset in the expression of HMGB-1 than in tumor necrosis factor-α, IL-1β, and IL-6 after spinal cord injury. The release of HMGB-1 from neurons and macrophages is mediated through the HMGB-1/RAGE or TLR pathways. HMGB-1 seems to play at least some roles in the proinflammatory cascade originating the secondary damage after the initial spinal cord injury.

Neuroprotective effects of Tacrolimus (FK-506) and Cyclosporin (CsA) in oxidative injury

The detrimental effects of hypoxic damage to central nervous system lead to energy depletion, free radical formation, lipid peroxidation (LPO), and increased calcium. We hypothesized that in vitro tacrolimus (FK-506) and cyclosporine A (CsA) could be protective against hypoxic damage in spinal cord. Dorsal columns were isolated from the spinal cord of adult rats and injured by exposure to hypoxic condition for 1 h, and treated with FK-506 (0.1 μM) and CsA (0.1 μM). After injury, reperfusion was carried out for 2 h. Tissues were collected, processed for biochemical assays, and 2,3,5-triphenyltetrazolium chloride (TTC) staining. Spinal cord hypoxia caused a significant decrease (P < 0.001) in mitochondrial ATP (30.64%) and tissue reduced glutathione (GSH) (60.14%) content. Conversely, a significant increase (P < 0.001) in tissue LPO level (57.77%) and myeloperoxidase (MPO) activity (461.24%) was observed in hypoxic group. Mitochondrial swelling was also significantly increased in hypoxic group (90.0%). Treatment with either FK-506 or CsA showed that significant neuroprotective effects (P < 0.05-0.01) were measured in various parameters in hypoxic groups. FK-506 and CsA treatment showed increase in ATP by 11.19% and 16.14% while GSH content increased by 66.46% and 77.32%, respectively. Conversely, LPO content decreased by 18.97% and 24.06% and MPO level by 42.86% and 18.66% after FK-506 and CsA treatment. Calcium uptake was also decreased in mitochondria as exhibited by the increase in absorbance by 11.19% after FK-506 treatment. TTC staining also showed increased viability after FK-506 and CsA treatment. In conclusion, present study demonstrates the neuroprotective effect of FK-506 and CsA treatment against spinal cord hypoxia induced damage is mediated via their antioxidant actions.

Inhibition of inflammation and oxidative stress by Angelica dahuricae radix extract decreases apoptotic cell death and improves functional recovery after spinal cord injury

Inflammation and oxidative stress play major roles in the pathogenesis after spinal cord injury (SCI). Here, we examined the neuroprotective effects of Angelica dahuricae radix (ADR) extract after SCI. ADR extract significantly decreased the levels of proinflammatory factors such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) in a lipopolysaccharide (LPS)-activated microglial cell line, BV2 cells. ADR extract also significantly alleviated the level of reactive oxygen species in LPS-activated BV2 cells. To examine the neuroprotective effect of ADR extract after SCI, spinally injured rats were administered ADR extract orally at a dose of 100 mg/kg for 14 days. ADR extract treatment significantly reduced the levels of TNF-α, IL-1β, IL-6, iNOS, and COX-2. The levels of superoxide anion (O(2·)(-)) and protein nitration were also significantly decreased by ADR extract. In addition, ADR extract inhibited p38 mitogen-activated protein kinase activation and pronerve growth factor expression in microglia after SCI. Furthermore, ADR extract significantly inhibited caspase-3 activation following apoptotic cell death of neurons and oligodendrocytes, thereby improving functional recovery after injury. Thus, our data suggest that ADR extract provides neuroprotection by alleviating inflammation and oxidative stress and can be used as an orally administered therapeutic agent for acute SCI.

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

Object

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

Methods

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

Results

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

Conclusions

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

Neuropathological differences between rats and mice after spinal cord injury

PURPOSE

To investigate the utility of noninvasive magnetic resonance imaging (MRI) protocols to demonstrate pathological differences between rats and mice after spinal cord injury (SCI). Rats and mice are commonly used to model SCI; however, histology and immunohistochemistry have shown differences in neuropathology between the two species, including cavity formation and scar/inflammatory responses.

MATERIALS AND METHODS

Moderate contusion SCI was performed on adult male rats and mice. At 28 days postinjury, animals underwent T1-weighted (T1W), with or without gadolinium contrast, or T2-weighted (T2W) magnetic resonance imaging (MRI), to be compared with histology at the same timepoint.

RESULTS

In both species, all MRI methods demonstrated changes in spinal cord anatomy. Immunohistochemistry indicated that T2W accurately reflected areas of inflammation and glial scar formation in rats and mice. Quantitation of lesion volume by histology and functional performance correlated best with T2W measurements in both species. Gadolinium contrast accurately reflected the blood-spinal cord-barrier permeability in both species, which appeared greater in rats than in mice.

CONCLUSION

These data demonstrate that MRI, with either a T1W or T2W protocol, can effectively distinguish pathological differences between rats and mice.

Delayed administration of dapsone protects from tissue damage and improves recovery after spinal cord injury

After spinal cord injury (SCI), a complex cascade of pathophysiological processes increases the primary damage. The inflammatory response plays a key role in this pathology. Recent evidence suggests that myeloperoxidase (MPO), an enzyme produced and released by neutrophils, is of special importance in spreading tissue damage. Dapsone (4,4'-diaminodiphenylsulfone) is an irreversible inhibitor of MPO. Recently, we demonstrated, in a model of brain ischemia/reperfusion, that dapsone has antioxidant, antiinflammatory, and antiapoptotic effects. The effects of dapsone on MPO activity, lipid peroxidation (LP) processes, motor function recovery, and the amount of spared tissue were evaluated in a rat model of SCI. MPO activity had increased 24.5-fold 24 hr after SCI vs. the sham group, and it had diminished by 38% and 19% in the groups treated with dapsone at 3 and 5 hr after SCI, respectively. SCI increased LP by 45%, and this increase was blocked by dapsone. In rats treated with dapsone, a significant motor function recovery (Basso-Beattie-Bresnahan score, BBB) was observed beginning during the first week of evaluation and continuing until the end of the study. Spontaneous recovery 8 weeks after SCI was 9.2 ± 1.12, whereas, in the dapsone-treated groups, it reached 13.6 ± 1.04 and 12.9 ± 1.17. Spared tissue increased by 42% and 33% in the dapsone-treated groups (3 and 5 hr after SCI, respectively) vs. SCI without treatment. Dapsone significantly prevented mortality. The results show that inhibition of MPO by dapsone significantly protected the spinal cord from tissue damage and enhanced motor recovery after SCI.

Limaprost reduces motor disturbances by increasing the production of insulin-like growth factor I in rats subjected to spinal cord injury

Calcitonin gene-related peptide (CGRP) released from sensory neurons increases the production of a neuroprotective substance insulin-like growth factor I (IGF-I), and sensory neuron stimulation contributes to a reduction of spinal cord injury (SCI) by inhibiting inflammatory responses in rats. Because receptors for prostaglandin E₂ (EP receptors) are present on sensory neurons, it is possible that prostaglandin E₁ analog limaprost reduces SCI by increasing IGF-I production through sensory neuron stimulation. We examined this possibility in rats subjected to compression-trauma-induced SCI. Limaprost increased the CGRP release from dorsal root ganglion (DRG) neurons isolated from rats, and this increase was reversed by pretreatment with the EP4 receptor antagonist ONO-AE3-208. Spinal cord tissue levels of CGRP and IGF-I were increased after the induction of SCI, peaking at 2 h postinduction. The intravenous administration of limaprost enhanced increases of spinal cord tissue levels of CGRP, IGF-I, and IGF-I mRNA at 2 h after the induction of SCI. Increases of spinal cord tissue levels of tumor necrosis factor, caspase-3, myeloperoxidase, and the number of apoptotic nerve cells were inhibited by the administration of limaprost. Motor disturbances of hind legs in animals subjected to the compression-trauma-induced SCI were reduced by the administration of limaprost. These effects of limaprost were reversed completely by pretreatment with a specific transient receptor potential vanilloid 1 inhibitor SB366791 and by sensory denervation. These observations strongly suggest that limaprost may increase the IGF-I production by stimulating sensory neurons in the spinal cord, thereby ameliorating compression-trauma-induced SCI through attenuation of inflammatory responses.

Melatonin plus exercise-based neurorehabilitative therapy for spinal cord injury

Spinal cord injury (SCI) is damage to the spinal cord caused by the trauma or disease that results in compromised or loss of body function. Subsequent to SCI in humans, many individuals have residual motor and sensory deficits that impair functional performance and quality of life. The available treatments for SCI are rehabilitation therapy, activity-based therapies, and pharmacological treatment using antioxidants and their agonists. Among pharmacological treatments, the most efficient and commonly used antioxidant for experimental SCI treatment is melatonin, an indolamine secreted by pineal gland at night. Melatonin's receptor-independent free radical scavenging action and its broad-spectrum antioxidant activity makes it an ideal antioxidant to protect tissue from oxidative stress-induced secondary damage after SCI. Owing to the limitations of an activity-based therapy and antioxidant treatment singly on the functional recovery and oxidative stress-induced secondary damages after SCI, a melatonin plus exercise treatment may be a more effective therapy for SCI. As suggested herein, supplementation with melatonin in conjunction with exercise not only would improve the functional recovery by enhancing the beneficial effects of exercise but would reduce the secondary tissue damage simultaneously. Finally, melatonin may protect against exercise-induced fatigue and impairments. In this review, based on the documented evidence regarding the beneficial effects of melatonin, activity-based therapy and the combination of both on functional recovery, as well as reduction of secondary damage caused by oxidative stress after SCI, we suggest the melatonin combined with exercise would be a novel neurorehabilitative strategy for the faster recovery after SCI.

Loss of hsp70.1 Decreases Functional Motor Recovery after Spinal Cord Injury in Mice

Heat shock proteins (HSPs) are specifically induced by various forms of stress. Hsp70.1, a member of the hsp70 family is known to play an important role in cytoprotection from stressful insults. However, the functional role of Hsp70 in motor function after spinal cord injury (SCI) is still unclear. To study the role of hsp70.1 in motor recovery following SCI, we assessed locomotor function in hsp70.1 knockout (KO) mice and their wild-type (WT) mice via the Basso, Beattie and Bresnahan (BBB) locomotor rating scale, before and after spinal hemisection at T13 level. We also examined lesion size in the spinal cord using Luxol fast blue/cresyl violet staining. One day after injury, KO and WT mice showed no significant difference in the motor function due to complete paralysis following spinal hemisection. However, when it compared to WT mice, KO mice had significantly delayed and decreased functional outcomes from 4 days up to 21 days after SCI. KO mice also showed significantly greater lesion size in the spinal cord than WT mice showed at 21 days after spinal hemisection. These results suggest that Hsp70 has a protective effect against traumatic SCI and the manipulation of the hsp70.1 gene may help improve the recovery of motor function, thereby enhancing neuroprotection after SCI.

Acupuncture-mediated inhibition of inflammation facilitates significant functional recovery after spinal cord injury

Here, we first demonstrated the neuroprotective effect of acupuncture after SCI. Acupuncture applied at two specific acupoints, Shuigou (GV26) and Yanglingquan (GB34) significantly alleviated apoptotic cell death of neurons and oligodendrocytes, thereby leading to improved functional recovery after SCI. Acupuncture also inhibited caspase-3 activation and reduced the size of lesion cavity and extent of loss of axons. We also found that the activation of both p38 mitogen-activated protein kinase and resident microglia after injury are significantly attenuated by acupuncture. In addition, acupuncture significantly reduced the expression or activation of pro-nerve growth factor, proinflammatory factors such as tumor necrosis factor-alpha, interleukin-1beta, interleukin-6, nitric oxide synthase, cycloxygenase-2, and matrix metalloprotease-9 after SCI. Thus, our results suggest that the neuroprotection by acupuncture may be partly mediated via inhibition of inflammation and microglial activation after SCI and acupuncture can be used as a potential therapeutic tool for treating acute spinal injury in human.

Traumatic brain injury may increase the risk for frontotemporal dementia through reduced progranulin

Frontotemporal lobar degeneration with TAR-DNA-binding protein inclusions (FTLD-TDP) is the most common pathological subtype of frontotemporal dementia (FTD). Mutations leading to a loss of function in the progranulin gene (PGRN) are the most common known cause of FTLD-TDP. In agreement with the proposed loss of function disease mechanism, several groups have reported decreased plasma levels of PGRN in patients carrying PGRN mutations compared to individuals without PGRN mutations. We propose that traumatic brain injury (TBI), an environmental factor, may also increase the risk of FTD by altering PGRN metabolism. TBI may lead to an increase in the central nervous system levels of microglial elastases, which proteolyze PGRN into proinflammatory products called granulins causing a reduction in PGRN levels. Hence, inhibiting microglial activation may have an important implication for the prevention of FTD in patients with TBI.

Modelo experimental de trauma medular agudo produzido por aparelho estereotáxico modificado

Foram utilizados 55 ratos machos da espécie Rattus novergicus, variedade Wistar, com o objetivo de propor um modelo experimental de trauma medular produzido por aparelho estereotáxico modificado, capaz de reproduzir clinicamente lesões medulares padronizadas. Após realização de laminectomia dorsal de T13, utilizou-se peso compressivo de 50,5g (25 animais - grupo I) ou 70,5g (30 animais - grupo II), durante cinco minutos, comprimindo a medula espinhal. Os animais foram assistidos durante oito dias, por meio de testes comportamentais para avaliar a sensibilidade dolorosa, a capacidade motora, o posicionamento tátil e proprioceptivo e a capacidade de manter-se em plano inclinado. No grupo I, observaram-se déficits neurológicos moderados e transitórios, que variaram entre os animais. No grupo II, foi possível obter um trauma padronizado, caracterizado por paraplegia bilateral e simétrica dos membros posteriores, perda de propriocepção e da sensibilidade dolorosa de todos os animais. A utilização do aparelho estereotáxico desenvolvido permite reproduzir clinicamente trauma medular padronizado em ratos, de maneira simples, econômica e satisfatória, o que poderá proporcionar avanços nas investigações terapêuticas, abrangendo doenças neurodegenerativas, como é o caso do trauma medular agudo.