Degenerative and regenerative mechanisms governing spinal cord injury

N-methyl-D-aspartate receptor antagonist MK-801 prevents apoptosis in rats that have undergone fetal spinal cord transplantation following spinal hemisection

Spinal cord injury is the main cause of paraplegia, but effective therapies for it are lacking. Embryonic spinal cord transplantation is able to repair spinal cord injury, albeit with a large amount of neuronal apoptosis remaining in the spinal cord. MK-801, an N-methyl-D-aspartate (NMDA) receptor antagonist, is able to reduce cell death by decreasing the concentration of excitatory amino acids and preventing extracellular calcium ion influx. In this study, the effect of MK-801 on the apoptosis of spinal cord neurons in rats that have received a fetal spinal cord (FSC) transplant following spinal hemisection was investigated. Wistar rats were divided into three groups: Spinal cord hemisection injury with a combination of FSC transplantation and MK-801 treatment (group A); spinal cord hemisection injury with FSC transplantation (group B); and spinal cord injury with insertion of a Gelfoam pledget (group C). The rats were sacrificed 1, 3, 7 and 14 days after the surgery. Apoptosis in spinal slices from the injured spinal cord was examined by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling reaction, and the expression of B-cell lymphoma-2 (Bcl-2) was measured by immunohistochemistry. The positive cells were quantitatively analyzed using a computer image analysis system. The rate of apoptosis and the positive expression of Bcl-2 protein in the spinal cord neurons in the three groups decreased in the following order: C>B>A (P<0.05) and A>B>C (P<0.05), respectively. This indicates that treatment with the NMDA receptor antagonist MK-801 prevents apoptosis in the spinal cord neurons of rats that have undergone FSC transplantation following spinal hemisection.

Identifying the role of microRNAs in spinal cord injury

Spinal cord injury (SCI) is medically and socioeconomically debilitating, and effective treatments are lacking. The elucidation of the pathophysiological mechanisms underlying SCI is essential for developing effective treatments for SCI. MicroRNAs (miRNAs) are small non-coding RNA molecules (18-24 nucleotides long) that regulate gene expression by interacting with specific target sequences. Recent studies suggest that miRNAs can act as post-transcriptional regulators to inhibit mRNA translation. Bioinformatic analyses indicate that the altered expression of miRNAs has an effect on critical processes of SCI physiopathology, including astrogliosis, oxidative stress, inflammation, apoptosis, and neuroplasticity. Therefore, the study of miRNAs may provide new insights into the molecular mechanisms of SCI. Current studies have also provided potential therapeutic clinical applications that involve targeting mRNAs to treat SCI. This review summarizes the biogenesis and function of miRNAs and the roles of miRNAs in SCI. We also discuss the potential therapeutic applications of miRNA-based interventions for SCI.

Chondroitin sulfate proteoglycans in the nervous system: inhibitors to repair

Chondroitin sulfate proteoglycans (CSPGs) are widely expressed in the normal central nervous system, serving as guidance cues during development and modulating synaptic connections in the adult. With injury or disease, an increase in CSPG expression is commonly observed close to lesioned areas. However, these CSPG deposits form a substantial barrier to regeneration and are largely responsible for the inability to repair damage in the brain and spinal cord. This review discusses the role of CSPGs as inhibitors, the role of inflammation in stimulating CSPG expression near site of injury, and therapeutic strategies for overcoming the inhibitory effects of CSPGs and creating an environment conducive to nerve regeneration.

Chondroitinase ABC plus bone marrow mesenchymal stem cells for repair of spinal cord injury

As chondroitinase ABC can improve the hostile microenvironment and cell transplantation is proven to be effective after spinal cord injury, we hypothesized that their combination would be a more effective treatment option. At 5 days after T8 spinal cord crush injury, rats were injected with bone marrow mesenchymal stem cell suspension or chondroitinase ABC 1 mm from the edge of spinal cord damage zone. Chondroitinase ABC was first injected, and bone marrow mesenchymal stem cell suspension was injected on the next day in the combination group. At 14 days, the mean Basso, Beattie and Bresnahan score of the rats in the combination group was higher than other groups. Hematoxylin-eosin staining showed that the necrotic area was significantly reduced in the combination group compared with other groups. Glial fibrillary acidic protein-chondroitin sulfate proteoglycan double staining showed that the damage zone of astrocytic scars was significantly reduced without the cavity in the combination group. Glial fibrillary acidic protein/growth associated protein-43 double immunostaining revealed that positive fibers traversed the damage zone in the combination group. These results suggest that the combination of chondroitinase ABC and bone marrow mesenchymal stem cell transplantation contributes to the repair of spinal cord injury.

Modulating inflammatory cell responses to spinal cord injury: all in good time

Spinal cord injury can have a range of debilitating effects, permanently impacting a patient's quality of life. Initially thought to be an immune privileged site, the spinal cord is able to mount a timely and well organized inflammatory response to injury. Intricate immune cell interactions are triggered, typically consisting of a staggered multiphasic immune cell response, which can become deregulated if left unchecked. Although several immunomodulatory compounds have yielded success in experimental rodent spinal cord injury models, their translation to human clinical studies needs further consideration. Because temporal differences between rodent and human inflammatory responses to spinal cord injury do exist, drug delivery timing will be a crucial component in recovery from spinal cord injury. Given too early, immunomodulatory therapies may impede beneficial inflammatory reactions to the injured spinal cord or even miss the opportunity to dampen delayed harmful autoimmune processes. Therefore, this review aims to summarize the temporal inflammatory response to spinal cord injury, as well as detailing specific immune cell functions. By clearly defining the chronological order of inflammatory events after trauma, immunomodulatory drug delivery timing can be better optimized. Further, we compare spinal cord injury-induced inflammatory responses in rodent and human studies, enabling clinicians to consider these differences when initiating clinical trials. Improved understanding of the cellular immune response after spinal cord injury would enhance the efficacy of immunomodulatory agents, enabling combined therapies to be considered.

Functional improvement following implantation of a microstructured, type-I collagen scaffold into experimental injuries of the adult rat spinal cord

The formation of cystic cavitation following severe spinal cord injury (SCI) constitutes one of the major barriers to successful axonal regeneration and tissue repair. The development of bioengineered scaffolds that assist in the bridging of such lesion-induced gaps may contribute to the formulation of combination strategies aimed at promoting functional tissue repair. Our previous in vitro investigations have demonstrated the directed axon regeneration and glial migration supporting properties of microstructured collagen scaffold that had been engineered to possess mechanical properties similar to those of spinal cord tissues. Here, the effect of implanting the longitudinally orientated scaffold into unilateral resection injuries (2mm long) of the mid-cervical lateral funiculus of adult rats has been investigated using behavioural and correlative morphological techniques. The resection injuries caused an immediate and long lasting (up to 12 weeks post injury) deficit of food pellet retrieval by the ipsilateral forepaw. Implantation of the orientated collagen scaffold promoted a significant improvement in pellet retrieval by the ipsilateral forepaw at 6 weeks which continued to improve up to 12 weeks post injury. In contrast, implantation of a non-orientated gelatine scaffold did not result in significant functional improvement. Surprisingly, the improved motor performance was not correlated with the regeneration of lesioned axons through the implanted scaffold. This observation supports the notion that biomaterials may support functional recovery by mechanisms other than simple bridging of the lesion site, such as the local sprouting of injured, or even non-injured fibres.

Sprouting of axonal collaterals after spinal cord injury is prevented by delayed axonal degeneration

After an incomplete spinal cord injury (SCI), partial recovery of locomotion is accomplished with time. Previous studies have established a functional link between extension of axon collaterals from spared spinal tracts and locomotor recovery after SCI, but the tissular signals triggering collateral sprouting have not been identified. Here, we investigated whether axonal degeneration after SCI contributes to the sprouting of collaterals from axons spared after injury. To this end, we evaluated collateral sprouting from BDA-labeled uninjured corticospinal axons after spinal cord hemisection (SCI(H)) in wild type (WT) mouse and Wld(S) mouse strains, which shows a significant delay in Wallerian degeneration after injury. After SCI(H), spared fibers of WT mice extend collateral sprouts to both intact and denervated sides of the spinal cord distant from the injury site. On the contrary, in the Wld(S) mice collateral sprouting from spared fibers was greatly reduced after SCI(H). Consistent with a role for collateral sprouting in functional recovery after SCI, locomotor recovery after SCI(H) was impaired in Wld(S) mice compared to WT animals. In conclusion, our results identify axonal degeneration as one of the triggers for collateral sprouting from the contralesional uninjured fibers after an SCI(H). These results open the path for identifying molecular signals associated with tissular changes after SCI that promotes collateral sprouting and functional recovery.

Expression of suppressor of cytokine signaling-3 (SOCS3) and its role in neuronal death after complete spinal cord injury

The present study investigates the endogenous expression of Suppressor of Cytokine Signaling-3 (SOCS3) after spinal cord injury (SCI) and its effect on SCI-induced cell death in vivo. In addition, we determined whether a reduction of SOCS3 expression induced by microinjection of short hairpin RNA (shSOCS3) carried by lentivirus into spinal cord provides cellular protection after SCI. We demonstrated that complete transection of rat T8 spinal cord induced SOCS3 expression at the mRNA and protein levels as early as 2days post-injury, which was maintained up to 14days. SOCS3 immunoreactivity was detected in neurons and activated microglia after SCI. We also demonstrated that SCI induces phosphorylation of proteins that are involved in signal transduction and transcription-3 (STAT3) in neurons, which induced SOCS3 expression. Western blot analyses and double-immunofluorescent staining showed significant up-regulation of the pro-apoptotic protein Bax, increases in the ratio of Bax to the anti-apoptotic protein Bcl-2, and up-regulation of cleaved caspase-3 in neurons. Treatment with shSOCS3 inhibited SCI-induced mRNA expression of SOCS3 2days post-injury and suppressed SCI-induced Bax expression 7days after SCI, both rostral and caudal to the lesion. Moreover, treatment with shSOCS3 inhibited SCI-induced neuronal death and protected neuronal morphology both rostral and caudal to the injury site 7days post-injury. Our results suggest that the STAT3/SOCS3 signaling pathway plays an important role in regulating neuronal death after SCI.

tPA promotes ADAMTS-4-induced CSPG degradation, thereby enhancing neuroplasticity following spinal cord injury

Although tissue plasminogen activator (tPA) is known to promote neuronal remodeling in the CNS, no mechanism of how this plastic function takes place has been reported so far. We provide here in vitro and in vivo demonstrations that this serine protease neutralizes inhibitory chondroitin sulfate proteoglycans (CSPGs) by promoting their degradation via the direct activation of endogenous type 4 disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS-4). Accordingly, in a model of compression-induced spinal cord injury (SCI) in rats, we found that administration of either tPA or its downstream effector ADAMTS-4 restores the tPA-dependent activity lost after the SCI and thereby, reduces content of CSPGs in the spinal cord, a cascade of events leading to an improved axonal regeneration/sprouting and eventually long term functional recovery. This is the first study to reveal a tPA-ADAMTS-4 axis and its function in the CNS. It also raises the prospect of exploiting such cooperation as a therapeutic tool for enhancing recovery after acute CNS injuries.

Survey of Cervical Spine Research Society members on the use of high-dose steroids for acute spinal cord injuries

STUDY DESIGN

A questionnaire survey.

OBJECTIVE

To characterize surgeons' current perspectives on the administration of methylprednisolone for acute spinal cord injury (SCI) and determine how this has changed during the last 7 years.

SUMMARY OF BACKGROUND DATA

The determinants of and complications associated with off-label steroid use for acute SCI remain controversial.

METHODS

A survey was sent to surgeon members of the Cervical Spine Research Society requesting information regarding their use of steroids for acute SCI. Determinants included surgeons' specialty, trauma center level, number of SCIs treated per year, severity of injury, and location of injury. These results were compared across groups as well as with a historical control.

RESULTS

In the case of cervical complete and incomplete SCIs, 47.4% and 56.4% of respondents, respectively, reported using steroids. For complete and incomplete thoracolumbar spine injuries, the usage rate was 46.2% and 55.1%, respectively. There has been a significant (P < 0.0001) decrease in the number of surgeons using high-dose steroids in the treatment of acute SCIs when compared with a previous report in 2006 (56% vs. 89%).More than 80% of respondents reported sepsis, active gastrointestinal bleeding, and SCI occurring earlier than 8 hours as contraindications. Seventy-one percent of respondents reported observing complications from the use of steroids, and 76.3% thought that the complications were severe enough to limit steroid use. Of the surgeons who used steroids for SCI, 26% thought that steroids improved neurological recovery, 19.2% used steroids to adhere to institutional protocol, and 25.6% stated they did not think steroids were beneficial but used them because of medicolegal concerns.

CONCLUSION

There has been a significant decrease in the number of surgeons using high-dose steroids for acute SCIs. Sepsis, gastrointestinal bleeding, and an injury occurring more than 8 hours prior to presentation were agreed upon as contraindications to steroid use.

The pathological changes in the spinal cord after dural tear with and without autologous fascia repair

PURPOSE

Dural tear is one of the common complications of spinal surgery leading to cerebrospinal fluid leakage followed by serial secondary symptoms. However, little is known about pathological changes of the spinal cord after dural tear. In the present study, we aimed to study the pathological changes in the spinal cord after dural tear with and without autologous fascia repair.

METHODS

Sixty Sprague-Dawley rats were used for dural tear and autologous fascia graft repair models. Three days and 1 week after surgery, the pathological changes in the spinal cord were analyzed by immunohistochemistry, Western blot, enzyme-linked immunosorbent assay and spinal somatosensory evoked potentials test.

RESULTS

Neuroinflammation was found in the parenchyma of the spinal cord characterized by gliosis, increased expression of inflammatory factors and infiltration of exogenesis immunocells in the rats without repair, which impaired the sensory conduction function of the spinal cord at the early stage of injury. Repairing with autologous fascia could attenuate neuroinflammation and help to maintain normal sensory conduction function of the spinal cord.

CONCLUSION

Dural tear could cause a series of inflammatory reactions in the spinal cord and further impair its sensory conduction function at the early stage of injury. Repairing with autologous fascia was a necessary and effective way to prevent the neuroinflammation and to maintain the normal function of the spinal cord.

Treatment of spinal cord injury with intravenous immunoglobulin G: preliminary evidence and future perspectives

Neuroinflammation plays an important role in the secondary pathophysiological mechanisms of spinal cord injury (SCI) and can exacerbate the primary trauma and thus worsen recovery. Although some aspects of the immune response are beneficial, it is thought that leukocyte recruitment and activation in the acute phase of injury results in the production of cytotoxic substances that are harmful to the nervous tissue. Therefore, suppression of excessive inflammation in the spinal cord could serve as a therapeutic strategy to attenuate tissue damage. The immunosuppressant methylprednisolone has been used in the setting of SCI, but there are complications which have attenuated the initial enthusiasm. Hence, there is interest in other immunomodulatory approaches, such as intravenous Immunoglobulin G (IVIg). Importantly, IVIg is used clinically for the treatment of several auto-immune neuropathies, such as Guillain-Barre syndrome, chronic inflammatory demyelinating polyneuropathy (CIPD) and Kawasaki disease, with a good safety profile. Thus, it is a promising treatment candidate for SCI. Indeed, IVIg has been shown by our team to attenuate the immune response and result in improved neurobehavioral recovery following cervical SCI in rats through a mechanism that involves the attenuation of neutrophil recruitment and reduction in the levels of cytokines and cytotoxic enzymes Nguyen et al. (J Neuroinflammation 9:224, 2012). Here we review published data in the context of relevant mechanisms of action that have been proposed for IVIg in other conditions. We hope that this discussion will trigger future research to provide supporting evidence for the efficiency and detailed mechanisms of action of this promising drug in the treatment of SCI, and to facilitate its clinical translation.

Canine epidermal neural crest stem cells: characterization and potential as therapy candidate for a large animal model of spinal cord injury

The discovery of multipotent neural crest-derived stem cells, named epidermal neural crest stem cells (EPI-NCSC), that persist postnatally in an easy-to-access location-the bulge of hair follicles-opens a spectrum of novel opportunities for patient-specific therapies. We present a detailed characterization of canine EPI-NCSC (cEPI-NCSC) from multiple dog breeds and protocols for their isolation and ex vivo expansion. Furthermore, we provide novel tools for research in canines, which currently are still scarce. In analogy to human and mouse EPI-NCSC, the neural crest origin of cEPI-NCSC is shown by their expression of the neural crest stem cell molecular signature and other neural crest-characteristic genes. Similar to human EPI-NCSC, cEPI-NCSC also expressed pluripotency genes. We demonstrated that cEPI-NCSC can generate all major neural crest derivatives. In vitro clonal analyses established multipotency and self-renewal ability of cEPI-NCSC, establishing cEPI-NCSC as multipotent somatic stem cells. A critical analysis of the literature on canine spinal cord injury (SCI) showed the need for novel treatments and suggested that cEPI-NCSC represent viable candidates for cell-based therapies in dog SCI, particularly for chondrodystrophic dogs. This notion is supported by the close ontological relationship between neural crest stem cells and spinal cord stem cells. Thus, cEPI-NCSC promise to offer not only a potential treatment for canines but also an attractive and realistic large animal model for human SCI. Taken together, we provide the groundwork for the development of a novel cell-based therapy for a condition with extremely poor prognosis and no available effective treatment.

MicroRNA dysregulation in spinal cord injury: causes, consequences and therapeutics

Trauma to the spinal cord causes permanent disability to more than 180,000 people every year worldwide. The initial mechanical damage triggers a complex set of secondary events involving the neural, vascular, and immune systems that largely determine the functional outcome of the spinal cord injury (SCI). Cellular and biochemical mechanisms responsible for this secondary injury largely depend on activation and inactivation of specific gene programs. Recent studies indicate that microRNAs function as gene expression switches in key processes of the SCI. Microarray data from rodent contusion models reveal that SCI induces changes in the global microRNA expression patterns. Variations in microRNA abundance largely result from alterations in the expression of the cells at the damaged spinal cord. However, microRNA expression levels after SCI are also influenced by the infiltration of immune cells to the injury site and the death and migration of specific neural cells after injury. Evidences on the role of microRNAs in the SCI pathophysiology have come from different sources. Bioinformatic analysis of microarray data has been used to identify specific variations in microRNA expression underlying transcriptional changes in target genes, which are involved in key processes in the SCI. Direct evidences on the role of microRNAs in SCI are scarcer, although recent studies have identified several microRNAs (miR-21, miR-486, miR-20) involved in key mechanisms of the SCI such as cell death or astrogliosis, among others. From a clinical perspective, different evidences make clear that microRNAs can be potent therapeutic tools to manipulate cell state and molecular processes in order to enhance functional recovery. The present article reviews the actual knowledge on how injury affects microRNA expression and the meaning of these changes in the SCI pathophysiology, to finally explore the clinical potential of microRNAs in the SCI.

Axoplasmic reticulum Ca(2+) release causes secondary degeneration of spinal axons

OBJECTIVE

Transected axons of the central nervous system fail to regenerate and instead die back away from the lesion site, resulting in permanent disability. Although both intrinsic (eg, microtubule instability, calpain activation) and extrinsic (ie, macrophages) processes are implicated in axonal dieback, the underlying mechanisms remain uncertain. Furthermore, the precise mechanisms that cause delayed "bystander" loss of spinal axons, that is, ones that were not directly damaged by the initial insult, but succumbed to secondary degeneration, remain unclear. Our goal was to evaluate the role of intra-axonal Ca(2+) stores in secondary axonal degeneration following spinal cord injury.

METHODS

We developed a 2-photon laser-induced spinal cord injury model to follow morphological and Ca(2+) changes in live myelinated spinal axons acutely following injury.

RESULTS

Transected axons "died back" within swollen myelin or underwent synchronous pan-fragmentation associated with robust Ca(2+) increases. Spared fibers underwent delayed secondary bystander degeneration. Reducing Ca(2+) release from axonal stores mediated by ryanodine and inositol triphosphate receptors significantly decreased axonal dieback and bystander injury. Conversely, a gain-of-function ryanodine receptor 2 mutant or pharmacological treatments that promote axonal store Ca(2+) release worsened these events.

INTERPRETATION

Ca(2+) release from intra-axonal Ca(2+) stores, distributed along the length of the axon, contributes significantly to secondary degeneration of axons. This refocuses our approach to protecting spinal white matter tracts, where emphasis has been placed on limiting Ca(2+) entry from the extracellular space across cell membranes, and emphasizes that modulation of axonal Ca(2+) stores may be a key pharmacotherapeutic goal in spinal cord injury.

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

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

Genome wide expression profiling during spinal cord regeneration identifies comprehensive cellular responses in zebrafish

BACKGROUND

Among the vertebrates, teleost and urodele amphibians are capable of regenerating their central nervous system. We have used zebrafish as a model to study spinal cord injury and regeneration. Relatively little is known about the molecular mechanisms underlying spinal cord regeneration and information based on high density oligonucleotide microarray was not available. We have used a high density microarray to profile the temporal transcriptome dynamics during the entire phenomenon.

RESULTS

A total of 3842 genes expressed differentially with significant fold changes during spinal cord regeneration. Cluster analysis revealed event specific dynamic expression of genes related to inflammation, cell death, cell migration, cell proliferation, neurogenesis, neural patterning and axonal regrowth. Spatio-temporal analysis of stat3 expression suggested its possible function in controlling inflammation and cell proliferation. Genes involved in neurogenesis and their dorso-ventral patterning (sox2 and dbx2) are differentially expressed. Injury induced cell proliferation is controlled by many cell cycle regulators and some are commonly expressed in regenerating fin, heart and retina. Expression pattern of certain pathway genes are identified for the first time during regeneration of spinal cord. Several genes involved in PNS regeneration in mammals like stat3, socs3, atf3, mmp9 and sox11 are upregulated in zebrafish SCI thus creating PNS like environment after injury.

CONCLUSION

Our study provides a comprehensive genetic blue print of diverse cellular response(s) during regeneration of zebrafish spinal cord. The data highlights the importance of different event specific gene expression that could be better understood and manipulated further to induce successful regeneration in mammals.

Scaffolds and stem cells: delivery of cell transplants for retinal degenerations

Retinal degenerations and optic neuropathies often lead to death of photoreceptors or retinal ganglion cells, respectively. Stem cell therapies are showing promise for these diseases in preclinical models and are beginning to transition into human trials, but cell delivery and integration remain major challenges. Focusing on photoreceptor- and progenitor-directed approaches, in this article, the authors review how advances in tissue engineering and cell scaffold design are enhancing cell therapies for retinal degeneration.

Squalenoyl adenosine nanoparticles provide neuroprotection after stroke and spinal cord injury

There is an urgent need to develop new therapeutic approaches for the treatment of severe neurological trauma, such as stroke and spinal cord injuries. However, many drugs with potential neuropharmacological activity, such as adenosine, are inefficient upon systemic administration because of their fast metabolization and rapid clearance from the bloodstream. Here, we show that conjugation of adenosine to the lipid squalene and the subsequent formation of nanoassemblies allows prolonged circulation of this nucleoside, providing neuroprotection in mouse stroke and rat spinal cord injury models. The animals receiving systemic administration of squalenoyl adenosine nanoassemblies showed a significant improvement of their neurologic deficit score in the case of cerebral ischaemia, and an early motor recovery of the hindlimbs in the case of spinal cord injury. Moreover, in vitro and in vivo studies demonstrated that the nanoassemblies were able to extend adenosine circulation and its interaction with the neurovascular unit. This Article shows, for the first time, that a hydrophilic and rapidly metabolized molecule such as adenosine may become pharmacologically efficient owing to a single conjugation with the lipid squalene.

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.

Curcumin promotes the spinal cord repair via inhibition of glial scar formation and inflammation

Spinal cord injury (SCI) is a serious clinical situation without any effective therapy to date. Traumatic SCI triggers a complex pathological process including inflammatory response and glial scar formation. In this study, we demonstrated that curcumin, a natural product which functions as an anti-inflammatory agent, inhibited the activation of signal transducer and activator of transcription-3 and NF-kappa B in the injured spinal cord. Curcumin treatment greatly reduced the astrogliosis in SCI mice and significantly decreased the expression of IL-1β and NO, as well as the number of Iba1(+) inflammatory cells at the lesion site. Notably, more residual axons and neurons were protected and significantly improved functional recovery was observed in the curcumin-treated mice, compared to the mice without curcumin treatment. These findings indicate that curcumin promotes spinal cord repair through inhibiting glial scar formation and inflammation and suggests the therapeutic potential of curcumin for SCI.

Dose-dependent anti-inflammatory and neuroprotective effects of an ανβ3 integrin-binding peptide

Previous studies have shown that prevention of leukocyte infiltration by targeting integrins involved in transendothelial migration may suppress the clinical and pathological features of neuroinflammatory disease. This study was designed to investigate the effects of C16, an ανβ3 integrin-binding peptide, in an acute experimental allergic encephalomyelitis (EAE) rat model. Multiple histological and immunohistochemical staining, electron microscopy observation, ELISA assay, Western blot, and magnetic resonance imaging (MRI) were employed to assess the degree of inflammation, axonal loss, neuronal apoptosis, white matter demyelination, and extent of gliosis in the brain and spinal cord of differently treated EAE models. The results showed that C16 treatment could inhibit extensive leukocyte and macrophage accumulation and infiltration and reduce cytokine tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) expression levels. A significantly lower clinical score at the peak time of disease was also demonstrated in the C16 treated group. Moreover, astrogliosis, demyelination, neuronal death, and axonal loss were all alleviated in C16 treated EAE animals, which may be attributed to the improvement of microenvironment. The data suggests that C16 peptide may act as a protective agent by attenuating inflammatory progression and thus affecting the expression of some proinflammatory cytokines during neuroinflammatory disease.

The role of secretory phospholipase A₂ in the central nervous system and neurological diseases

Secretory phospholipase A2 (sPLA2s) are small secreted proteins (14-18 kDa) and require submillimolar levels of Ca(2+) for liberating arachidonic acid from cell membrane lipids. In addition to the enzymatic function, sPLA2 can exert various biological responses by binding to specific receptors. Physiologically, sPLA2s play important roles on the neurotransmission in the central nervous system and the neuritogenesis in the peripheral nervous system. Pathologically, sPLA2s are involved in the neurodegenerative diseases (e.g., Alzheimer's disease) and cerebrovascular diseases (e.g., stoke). The common pathology (e.g., neuronal apoptosis) of Alzheimer's disease and stroke coexists in the mixed dementia, suggesting common pathogenic mechanisms of the two neurological diseases. Among mammalian sPLA2s, sPLA2-IB and sPLA2-IIA induce neuronal apoptosis in rat cortical neurons. The excess influx of calcium into neurons via L-type voltage-dependent Ca(2+) channels mediates the two sPLA2-induced apoptosis. The elevated concentration of intracellular calcium activates PKC, MAPK and cytosolic PLA2. Moreover, it is linked with the production of reactive oxygen species and apoptosis through activation of the superoxide producing enzyme NADPH oxidase. NADPH oxidase is involved in the neurotoxicity of amyloid β peptide, which impairs synaptic plasticity long before its deposition in the form of amyloid plaques of Alzheimer's disease. In turn, reactive oxygen species from NADPH oxidase can stimulate ERK1/2 phosphorylation and activation of cPLA2 and result in a release of arachidonic acid. sPLA2 is up-regulated in both Alzheimer's disease and cerebrovascular disease, suggesting the involvement of sPLA2 in the common pathogenic mechanisms of the two diseases. Thus, our review presents evidences for pathophysiological roles of sPLA2 in the central nervous system and neurological diseases.

Activation of heme oxygenase recovers motor function after spinal cord injury in rats

Characterization of auto-destructive mechanisms, leading to cell death after spinal cord injury (SCI) is important to prevent further damage to tissue. Heme oxygenase (HO) catalyzes the oxidation of heme to biliverdin and carbon monoxide (CO), as a response to cell damage. Products of HO action have biological effects, as antioxidant biliverdin. We evaluated the changes of HO activity after injury, and the effect of pharmacological treatments with hemin (an inducer) and (Sn)-protoporphyrin (an inhibitor, Sn-PPIX) of HO, upon motor recovery after SCI. Female Wistar rats were submitted to SCI by trauma and sacrificed at several times (2, 4, 8, 12 and 24h) after injury to evaluate HO activity. Additional groups of rats were treated with either hemin or Sn-PPIX, to evaluate motor recovery, spared spinal cord tissue and HO activity. Results showed that HO control activity was increased by effect of SCI, at all times evaluated, as compared to sham group values. Twenty-four hours after injury, HO activity was increased 7.2-fold by hemin treatment, as compared to SCI plus vehicle group values. In addition, animals treated with hemin 2 and 8h after SCI, showed a better motor recovery and higher spared cord tissue, as compared to control group values. Our findings indicate that activation of HO is a beneficial mechanism when attained during the acute phase after SCI.

Immunopharmacological intervention for successful neural stem cell therapy: New perspectives in CNS neurogenesis and repair

The pharmacological support and stimulation of endogenous and transplanted neural stem cells (NSCs) is a major challenge in brain repair. Trauma to the central nervous system (CNS) results in a distinct inflammatory response caused by local and infiltrating immune cells. This makes NSC-supported regeneration difficult due to the presence of inhibitory immune factors which are upregulated around the lesion site. The continual and dual role of the neuroinflammatory response leaves it difficult to decipher upon a single modulatory strategy. Therefore, understanding the influence of cytokines upon regulation of NSC self-renewal, proliferation and differentiation is crucial when designing therapies for CNS repair. There is a plethora of partially conflicting data in vitro and in vivo on the role of cytokines in modulating the stem cell niche and the milieu around NSC transplants. This is mainly due to the pleiotropic role of many factors. In order for cell-based therapy to thrive, treatment must be phase-specific to the injury and also be personalized for each patient, i.e. taking age, sex, neuroimmune and endocrine status as well as other key parameters into consideration. In this review, we will summarize the most relevant information concerning interleukin (IL)-1, IL-4, IL-10, IL-15, IFN-γ, the neuropoietic cytokine family and TNF-α in order to extract promising therapeutic approaches for further research. We will focus on the consequences of neuroinflammation on endogenous brain stem cells and the transplantation environment, the effects of the above cytokines on NSCs, as well as immunopharmacological manipulation of the microenvironment for potential therapeutic use.

Demyelination initiated by oligodendrocyte apoptosis through enhancing endoplasmic reticulum-mitochondria interactions and Id2 expression after compressed spinal cord injury in rats

BACKGROUND

Demyelination is one of the most important pathological factors of spinal cord injury. Oligodendrocyte apoptosis is involved in triggering demyelination. However, fewer reports on pathological changes and mechanism of demyelination have been presented from compressed spinal cord injury (CSCI). The relative effect of oligodendrocyte apoptosis on CSCI-induced demyelination and the mechanism of apoptosis remain unclear.

AIMS

In this study, a custom-designed model of CSCI was used to determine whether or not demyelination and oligodendrocyte apoptosis occur after CSCI. The pathological changes in axonal myelinated fibers were investigated by osmic acid staining and transmission electron microscopy. Myelin basic protein (MBP), which is used in myelin formation in the central nervous system, was detected by immunofluorescence and Western blot assays. Oligodendrocyte apoptosis was revealed by in situ terminal-deoxytransferase-mediated dUTP nick-end labeling. To analyze the mechanism of oligodendrocyte apoptosis, we detected caspase-12 [a representative of endoplasmic reticulum (ER) stress], cytochrome c (an apoptotic factor and hallmark of mitochondria), and inhibitor of DNA binding 2 (Id2, an oligodendrocyte lineage gene) by immunofluorescence and Western blot assays.

RESULTS

The custom-designed model of CSCI was successfully established. The rats were spastic, paralyzed, and incontinent. The Basso, Beattie, and Bresnahan (BBB) locomotor rating scale scores were decreased as time passed. The compressed spinal cord slices were ischemic. Myelin sheaths became swollen and degenerative; these sheaths were broken down as time passed after CSCI. MBP expression was downregulated after CSCI and consistent with the degree of demyelination. Oligodendrocyte apoptosis occurred at 1 day after CSCI and increased as caspase-12 expression was enhanced and cytochrome c was released. Id2 was distributed widely in the white matter. Id2 expression increased with time after CSCI.

CONCLUSION

Demyelination occurred after CSCI and might be partly caused by oligodendrocyte apoptosis, which was positively correlated with ER-mitochondria interactions and enhanced Id2 expression after CSCI in rats.

Directed migration in neural tissue engineering

Directed cell migration is particularly important in neural tissue engineering, where the goal is to direct neurons and support cells across injured nerve gaps. Investigation of the gradients present in the body during development provides an approach to guiding cells in peripheral and central nervous system tissue, but many different types of gradients and patterns can accomplish directed migration. The focus of this review is to describe current research paradigms in neural tissue gradients and review their effectiveness for directed migration. The review explores directed migration achieved through the use of chemical, adhesive, mechanical, topographical, and electrical types of gradients. Few studies investigate combined gradients, though it is known that a combination of therapies is necessary for reconnection of neuronal circuitry. To date, there has been no systematic review of gradient approaches to neural tissue engineering. By looking at effectiveness of various scaffold cue presentation and methods to combine these strategies, the potential for nerve repair is increased.

P45 forms a complex with FADD and promotes neuronal cell survival following spinal cord injury

Fas-associated death domain (DD) adaptor (FADD), a member of the DD superfamily, contains both a DD and a death effector domain (DED) that are important in mediating FAS ligand-induced apoptotic signaling. P45 is a unique member of the DD superfamily in that it has a domain with sequence and structural characteristics of both DD and DED. We show that p45 forms a complex with FADD and diminishes Fas-FADD mediated death signaling. The DED of FADD is required for the complex formation with p45. Following spinal cord injury, transgenic mice over-expressing p45 exhibit increased neuronal survival, decreased retraction of corticospinal tract fibers and improved functional recovery. Understanding p45-mediated cellular and molecular mechanisms may provide insights into facilitating nerve regeneration in humans.

Gastrodin promotes the secretion of brain-derived neurotrophic factor in the injured spinal cord

Gastrodin, an active component of tall gastrodia tuber, is widely used in the treatment of dizziness, paralysis, epilepsy, stroke and dementia, and exhibits a neuroprotective effect. A rat model of spinal cord injury was established using Allen's method, and gastrodin was administered via the subarachnoid cavity and by intraperitoneal injection for 7 days. Results show that gastrodin promoted the secretion of brain-derived neurotrophic factor in rats with spinal cord injury. After gastrodin treatment, the maximum angle of the inclined plane test, and the Basso, Beattie and Bresnahan scores increased. Moreover, gastrodin improved neural tissue recovery in the injured spinal cord. These results demonstrate that gastrodin promotes the secretion of brain-derived neurotrophic factor, contributes to the recovery of neurological function, and protects neural cells against injury.

The Ryk receptor is expressed in glial and fibronectin-expressing cells after spinal cord injury

Wnt proteins play a critical role in central nervous system development and have been implicated in several neuropathologies, including spinal cord injury (SCI). Ryk, an unconventional Wnt receptor, regulates axonal regeneration after SCI, although its expression pattern in this neuropathology remains unclear. Therefore, we sought to define the spatiotemporal and cellular pattern of Ryk expression after a contusive SCI in adult rats using quantitative reverse transcription polymerase chain reaction (RT-PCR), Western blot, and immunohistochemical analysis. Under physiological conditions, Ryk is expressed in neurons, astrocytes, and blood vessels, but not in oligodendrocytes, microglia, NG2+ glial precursor cells, or axonal projections. Following SCI, we observed an increase in Ryk mRNA expression from 24 h post-injury until 7 days post-injury, whereas its protein levels were significantly augmented at 7 and 14 days post-injury. Moreover, the spatial and cellular Ryk expression pattern was altered in the damaged tissue, where this receptor was observed in reactive astrocytes and microglia/macrophages, NG2+ glial precursors, fibronectin+ cells, oligodendrocytes, and axons. In conclusion, we demonstrate that Ryk is expressed in the unlesioned spinal cord and that, after SCI, its spatiotemporal and cellular expression pattern changed dramatically, being expressed in cells involved in the spinal cord response to damage.

Systematic Review of Induced Pluripotent Stem Cell Technology as a Potential Clinical Therapy for Spinal Cord Injury

Transplantation therapies aimed at repairing neurodegenerative and neuropathological conditions of the central nervous system (CNS) have utilized and tested a variety of cell candidates, each with its own unique set of advantages and disadvantages. The use and popularity of each cell type is guided by a number of factors including the nature of the experimental model, neuroprotection capacity, the ability to promote plasticity and guided axonal growth, and the cells' myelination capability. The promise of stem cells, with their reported ability to give rise to neuronal lineages to replace lost endogenous cells and myelin, integrate into host tissue, restore functional connectivity, and provide trophic support to enhance and direct intrinsic regenerative ability, has been seen as a most encouraging step forward. The advent of the induced pluripotent stem cell (iPSC), which represents the ability to “reprogram” somatic cells into a pluripotent state, hails the arrival of a new cell transplantation candidate for potential clinical application in therapies designed to promote repair and/or regeneration of the CNS. Since the initial development of iPSC technology, these cells have been extensively characterized in vitro and in a number of pathological conditions and were originally reported to be equivalent to embryonic stem cells (ESCs). This review highlights emerging evidence that suggests iPSCs are not necessarily indistinguishable from ESCs and may occupy a different “state” of pluripotency with differences in gene expression, methylation patterns, and genomic aberrations, which may reflect incomplete reprogramming and may therefore impact on the regenerative potential of these donor cells in therapies. It also highlights the limitations of current technologies used to generate these cells. Moreover, we provide a systematic review of the state of play with regard to the use of iPSCs in the treatment of neurodegenerative and neuropathological conditions. The importance of balancing the promise of this transplantation candidate in the light of these emerging properties is crucial as the potential application in the clinical setting approaches. The first of three sections in this review discusses (A) the pathophysiology of spinal cord injury (SCI) and how stem cell therapies can positively alter the pathology in experimental SCI. Part B summarizes (i) the available technologies to deliver transgenes to generate iPSCs and (ii) recent data comparing iPSCs to ESCs in terms of characteristics and molecular composition. Lastly, in (C) we evaluate iPSC-based therapies as a candidate to treat SCI on the basis of their neurite induction capability compared to embryonic stem cells and provide a summary of available in vivo data of iPSCs used in SCI and other disease models.

Signaling pathways regulating dose-dependent dual effects of TNF-α on primary cultured Schwann cells

After peripheral nerve injury, Schwann cells are rapidly activated to participate in the regenerative process and modulate local immune reactions. Tumor necrosis factor-α (TNF-α), one of the major initiators of the inflammatory cascade, has been known to exert pleiotropic functions during peripheral nerve injury and regeneration. In this study, we aimed to investigate the in vitro effects of TNF-α on peripheral neural cells. First, gene-microarray analysis was applied to the RNA samples extracted from injured peripheral nerves, providing the information of gene interactions post nerve injury. Then, after primary cultured Schwann cells were treated with increasing dosages (0-40 ng/ml) of TNF-α, cell proliferation and migration were examined by EdU incorporation and a transwell-based assay, and cell apoptosis was observed and quantified by electron microscopy and Annexin V-FITC assay, respectively. The results showed that lower dosages of TNF-α increased cell proliferation and migration, whereas higher dosages of TNF-α decreased cell proliferation and migration and enhanced cell apoptosis. The tests using a chemical inhibitor of TNF-α further confirmed the above effects of TNF-α. To understand how TNF-α produced the dose-dependent dual effects on primary cultured Schwann cells, we performed co-immunoprecipitation, Western blot analysis, and immunocytochemistry to decipher the complex network of biochemical pathways involving many signaling molecules, i.e., TNF receptor-associated death domain, Fas-associated death domain, receptor interacting protein, JNK, NF-κB p65, and caspases, thus assuming the mechanisms by which TNF-α activated the death and survival pathways and achieved a balance between the two opposite actions in primary cultured Schwann cells.

Multiple sclerosis: does Nogo play a role?

Over the past decade, there has been substantial interest in the role of the integral myelin protein, Nogo-A, from fundamental neurobiological to clinical perspectives. It is now a well-known inhibitor of neurite outgrowth through its cognate receptor, Nogo receptor 1 (NgR1). Nogo-A can only signal through NgR1 upon heteromeric collaboration with p75(NTR), TROY, and LINGO-1 to induce axonal retraction. Both Nogo-A and NgR1 are expressed in multiple sclerosis (MS) lesions, suggesting that Nogo signaling may play a pivotal role in disease progression. There are several approaches targeting Nogo signaling in animal models of MS, and these therapeutic effects are currently in debate. One of the points of contention arises from the localization of the aforementioned signaling molecules, considering that MS and its animal models of disease are governed by inflammatory infiltration of the central nervous system. Furthermore, an impressive list of ligands for NgR1 continues to be compiled, possibly leading to disparities in the results obtained from the various animal models. In this review, we systematically dissect the complexities of Nogo signaling, which may be relevant in the future directions of neuroprotective therapies for MS.

Expression of G-protein-coupled receptor kinase 6 (GRK6) after acute spinal cord injury in adult rat

Spinal cord injury frequently results in permanent loss of neurological function. It includes many complex molecular and biochemical mechanisms. G-protein-coupled receptor kinase 6 (GRK6) is an intracellular kinase that regulates the sensitivity of certain G-protein-coupled receptors. Some studies reported GRK2 and GRK5 modulate the NFκB pathway in macrophages. Additionally, GRK2 is referred to as regulating activation of spinal cord microglia and GRK6 expression is significantly elevated in most brain regions in the MPTP-lesioned parkinsonian monkeys. However, the expression and function of GRK6 in nervous system lesion and repair are not well understood. In this study, we performed an acute spinal cord injury (SCI) model in adult rats. Western blot analysis showed the expression of GRK6 was upregulated significantly at protein level in spinal cord after SCI. Immunohistochemistry and immunofluorescence revealed wide expression of GRK6 in the normal spinal cord. After injury, GRK6 expression was increased predominantly in microglia, which expressed F4/80 (marker of macrophages and activated microglia) strongly. To understand whether GRK6 played a role in microglia activation, we applied lipopolysaccharide (LPS) to induce microglia activation in vitro. Western blot analysis demonstrated up-regulation in GRK6 protein expression after LPS stimulation was time- and dose-dependent and that up-regulation in F4/80 expression was concomitant with GRK6. These data suggested that GRK6 might be involved in the pathophysiology of SCI.

The Transcriptional Response of Neurotrophins and Their Tyrosine Kinase Receptors in Lumbar Sensorimotor Circuits to Spinal Cord Contusion is Affected by Injury Severity and Survival Time

Traumatic spinal cord injury (SCI) results in changes to the anatomical, neurochemical, and physiological properties of cells in the central and peripheral nervous system. Neurotrophins, acting by binding to their cognate Trk receptors on target cell membranes, contribute to modulation of anatomical, neurochemical, and physiological properties of neurons in sensorimotor circuits in both the intact and injured spinal cord. Neurotrophin signaling is associated with many post-SCI changes including maladaptive plasticity leading to pain and autonomic dysreflexia, but also therapeutic approaches such as training-induced locomotor improvement. Here we characterize expression of mRNA for neurotrophins and Trk receptors in lumbar dorsal root ganglia (DRG) and spinal cord after two different severities of mid-thoracic injury and at 6 and 12 weeks post-SCI. There was complex regulation that differed with tissue, injury severity, and survival time, including reversals of regulation between 6 and 12 weeks, and the data suggest that natural regulation of neurotrophins in the spinal cord may continue for months after birth. Our assessments determined that a coordination of gene expression emerged at the 12-week post-SCI time point and bioinformatic analyses address possible mechanisms. These data can inform studies meant to determine the role of the neurotrophin signaling system in post-SCI function and plasticity, and studies using this signaling system as a therapeutic approach.

Spatio-temporal expression pattern of frizzled receptors after contusive spinal cord injury in adult rats

Background

Wnt proteins are a large family of molecules that are critically involved in multiple central nervous system (CNS) developmental processes. Experimental evidences suggest a role for this family of proteins in many CNS disorders, including spinal cord injury (SCI), which is a major neuropathology owing to its high prevalence and chronic sensorimotor functional sequelae. Interestingly, most Wnt proteins and their inhibitors are expressed in the uninjured spinal cord, and their temporal expression patterns are dramatically altered after injury. However, little is known regarding the expression of their better-known receptors, the Frizzled family, after SCI. Thus, the aim of the present study was to evaluate the expression of Frizzled receptors in the damaged spinal cord.

Findings

Based on the evidence that Wnts are expressed in the spinal cord and are transcriptionally regulated by SCI in adulthood, we analysed the spatio-temporal mRNA and protein expression patterns of Frizzled receptors after contusive SCI using quantitative RT-PCR and single and double immunohistochemistry, respectively. Our results show that almost all of the 10 known Frizzled receptors were expressed in specific spatial patterns in the uninjured spinal cords. Moreover, the Frizzled mRNAs and proteins were expressed after SCI, although their expression patterns were altered during the temporal progression of SCI. Finally, analysis of cellular Frizzled 5 expression pattern by double immunohistochemistry showed that, in the uninjured spinal cord, this receptor was expressed in neurons, oligodendrocytes, astrocytes, microglia and NG2⁺ glial precursors. After injury, Frizzled 5 was not only still expressed in oligodendrocytes, astrocytes and NG2⁺ glial precursors but also in axons at all evaluated time points. Moreover, Frizzled 5 was expressed in reactive microglia/macrophages from 3 to 14 days post-injury.

Conclusions

Our data suggest the involvement of Frizzled receptors in physiological spinal cord function and in the cellular and molecular events that characterise its neuropathology.

Peripheral mineralization of a 3D biodegradable tubular construct as a way to enhance guidance stabilization in spinal cord injury regeneration

Spinal cord injuries (SCI) present a major challenge to therapeutic development due to its complexity. Combinatorial approaches using biodegradable polymers that can simultaneously provide a tissue scaffold, a cell vehicle, and a reservoir for sustained drug delivery have shown very promising results. In our previous studies we have developed a novel hybrid system consisting of starch/poly-e-caprolactone (SPCL) semi-rigid tubular porous structure, based on a rapid prototyping technology, filled by a gellan gum hydrogel concentric core for the regeneration within spinal-cord injury sites. In the present work we intend to promote enhanced osteointegration on these systems by pre-mineralizing specifically the external surfaces of the SPCL tubular structures, though a biomimetic strategy, using a sodium silicate gel as nucleating agent. The idea is to create two different cell environments to promote axonal regeneration in the interior of the constructs while inducing osteogenic activity on its external surface. By using a Teflon cylinder to isolate the interior of the scaffold, it was possible to observe the formation of a bone-like poorly crystalline carbonated apatite layer continuously formed only in the external side of the tubular structure. This biomimetic layer was able to support the adhesion of Bone Marrow Mesenchymal Stem Cells, which have gone under cytoskeleton reorganization in the first hours of culture when compared to cells cultured on uncoated scaffolds. This strategy can be a useful route for locally stimulate bone tissue regeneration and facilitating early bone ingrowth.

Bog bilberry anthocyanin extract improves motor functional recovery by multifaceted effects in spinal cord injury

The aim of this study was to determine the therapeutic efficiency of bog bilberry anthocyanin extract (BBAE) treatment starting 1 d after spinal cord injury (SCI) in rats and to investigate the underlying mechanism. The BBAE contained cyanidin-3-glucoside, malvidin-3-galactoside and malvidin-3-glucoside. SCI models were induced using the weight-drop method in Sprague-Dawley rats and additionally with sham group (laminectomy only). The animals were divided into four groups: vehicle-treated group; 10 mg/kg BBAE-treated group; 20 mg/kg BBAE-treated group; sham group. BBAE-treated or vehicle-treated group was administered orally at one day after SCI and then daily for 8 weeks. Locomotor functional recovery was assessed during the 8 weeks post operation period by performing a Basso, Beattie, and Bresnahan (BBB) locomotor score test. At the end of study, the animals were killed, and 1.5 cm segments of spinal cord encompassing the injury site were removed for immunohistochemistry, histopathological and western blotting analysis. Immunohistochemistry for GFAP, aggrecan, neurocan and NeuN was used to assess the degree of astrocytic glial scar formation and neuron survival. Immunohistochemistry and western blotting analysis for TNF-α, IL-6, IL-1β was used to evaluate the anti-inflammation effect of BBAE. To evaluate its inhibition effect on the astrocytes, we performed the MTT assay and immunohistochemistry for Ki67 in vitro. Results show that the BBAE-treated animals showed significantly better locomotor functional recovery, neuron death and smaller glial scar formation after spinal cord injury in vivo. In addition, BBAE administration could inhibit astrocyte proliferation in vivo and vitro. Therefore, BBAE may be useful as a promising therapeutic agent for SCI.

Immunoglobulin G (IgG) attenuates neuroinflammation and improves neurobehavioral recovery after cervical spinal cord injury

Background

Evidence suggests that the inflammatory events in the acute phase of spinal cord injury (SCI) exacerbate the initial trauma to the cord leading to poor functional recovery. As a result, minimizing the detrimental aspects of the inflammatory response after SCI is a promising treatment strategy. In this regard, immunoglobulin G (IgG) from pooled human serum is a promising treatment candidate. Due to its putative, though poorly characterized immuno-modulatory effects, IgG has been used clinically to treat neuroinflammatory disorders such as Guillain-Barré syndrome, but its effects in neurotrauma remain largely unexplored.

Methods

This study examines the potential neuroprotective effects of IgG in a well-characterized cervical model of SCI. Female Wistar rats were subject to moderate-severe clip compression injury at the C7-T1 level. IgG (0.4 g/kg) or saline was injected intravenously to randomly selected animals at 15 min post SCI. At several time points post SCI, biochemical assays, histology and immunohistochemistry analyses, and neurobehavioral assessments were used to examine the neuroprotective effects of IgG at the molecular, cellular, and neurobehavioral levels.

Results

We found that intravenous treatment of IgG following acute clip-compression SCI at C7-T1 significantly reduced two important inflammatory cytokines: interleukin (IL)-1β and IL-6. This early reduction in pro-inflammatory signaling was associated with significant reductions in neutrophils in the spinal cord and reductions in the expression of myeloperoxidase and matrix metalloproteinase-9 in the injured spinal cord at 24 h after SCI. These beneficial effects of IgG were associated with enhanced tissue preservation, improved neurobehavioral recovery as measured by the BBB and inclined plane tests, and enhanced electrophysiological evidence of central axonal conduction as determined by motor-evoked potentials.

Conclusion

The findings from this study indicate that IgG is a novel immuno-modulatory therapy which shows promise as a potential treatment for SCI.