Clip compression injury in the spinal cord: a correlative study of neurological and morphological alterations

Characterizing the Impact of Compression Duration and Deformation-Related Loss of Closure Force on Clip-Induced Spinal Cord Injury in Rats

The clip-induced spinal cord injury (SCI) rat model is pivotal in preclinical SCI research. However, the literature exhibits variability in compression duration and limited attention to clip deformation-related loss of closure force. We aimed to investigate the impact of compression duration on SCI severity and the influence of clip deformation on closure force. Rats received T10-level clip-induced SCI with durations of 1, 5, 10, 20, and 30 s, and a separate group underwent T10 transection. Outcomes included functional, histological, electrophysiological assessments, and inflammatory cytokine analysis. A tactile pressure mapping system quantified clip closure force after open-close cycles. Our results showed a positive correlation between compression duration and the severity of functional, histological, and electrophysiological deficits. Remarkably, even a brief 1-s compression caused significant deficits comparable to moderate-to-severe SCI. SSEP waveforms were abolished with durations over 20 s. Decreased clip closure force appeared after five open-close cycles. This study offers critical insights into regulating SCI severity in rat models, aiding researchers. Understanding compression duration and clip fatigue is essential for experiment design and interpretation using the clip-induced SCI model.

The immune microenvironment and tissue engineering strategies for spinal cord regeneration

Regeneration of neural tissue is limited following spinal cord injury (SCI). Successful regeneration of injured nerves requires the intrinsic regenerative capability of the neurons and a suitable microenvironment. However, the local microenvironment is damaged, including insufficient intraneural vascularization, prolonged immune responses, overactive immune responses, dysregulated bioenergetic metabolism and terminated bioelectrical conduction. Among them, the immune microenvironment formed by immune cells and cytokines plays a dual role in inflammation and regeneration. Few studies have focused on the role of the immune microenvironment in spinal cord regeneration. Here, we summarize those findings involving various immune cells (neutrophils, monocytes, microglia and T lymphocytes) after SCI. The pathological changes that occur in the local microenvironment and the function of immune cells are described. We also summarize and discuss the current strategies for treating SCI with tissue-engineered biomaterials from the perspective of the immune microenvironment.

Effects of repetitive magnetic stimulation on motor function and GAP43 and 5-HT expression in rats with spinal cord injury

Objectives

Spinal cord injury (SCI) is a disabling central nervous system disorder. This study aimed to explore the effects of repetitive trans-spinal magnetic stimulation (rTSMS) of different spinal cord segments on movement function and growth-associated protein-43 (GAP43) and 5-hydroxytryptamine (5-HT) expression in rats after acute SCI and to preliminarily discuss the optimal rTSMS treatment site to provide a theoretical foundation and experimental evidence for clinical application of rTSMS in SCI.

Methods

A rat T10 laminectomy SCI model produced by transient application of an aneurysm clip was used in the study. The rats were divided into group A (sham surgery), group B (acute SCI without stimulation), group C (T6 segment stimulation), group D (T10 segment stimulation), and group E (L2 segment stimulation).

Results

In vivo magnetic stimulation protected motor function, alleviated myelin sheath damage, decreased NgR and Nogo-A expression levels, increased GAP43 and 5-HT expression levels, and inhibited terminal deoxynucleotidyl transferase dUTP nick end labeling-positive cells and apoptosis-related protein expression in rats at 8 weeks after the surgery.

Conclusions

This study suggests that rTSMS can promote GAP43 and 5-HT expression and axonal regeneration in the spinal cord, which is beneficial to motor function recovery after acute SCI.

Neuroserpin restores autophagy and promotes functional recovery after acute spinal cord injury in rats

This study is to reveal the characteristics of autophagy and the effect of neuroserpin (NSP) treatment on autophagy during the process of functional recovery following spinal cord injury (SCI). After the clip compress rat model of SCI had been made, autophagy‑associated proteins, including LC3‑II, beclin‑1 and p62, were evaluated at 2, 4, 24, 72 h, and 168 h in the experimental group, and the sham group as control. Transmission electron microscopy (TEM) was further used for autophagy detection at 4 and 72 h. All the male rats were randomly divided into three groups: Sham, vehicle and NSP group. NSP or an equal volume of saline vehicle was administered via intrathecal injection immediately after SCI. Each group was further divided into subgroups for the following experiments: i)Western blot (LC3‑II and p62); ii) Immunofluorescent double staining (LC3/MAP‑2/DAPI); iii) Nissl staining and Basso Beattie Bresnahan (BBB score) for NSP neuroprotection evaluation. Our results revealed both LC3‑II and p62 expression trended upward at 24, 72 and 168 h after SCI. The LC3‑II peaked at 72 h, while p62 peaked at 24 h. Beclin‑1 dropped significantly at 72 and 168 h. TEM results showed that autophagosomes largely accumulated at 72 h after SCI when compared with the sham group. Western blot analysis showed that LC3‑II and p62 were markedly decreased with NSP treatment at 72 h after injury compared with that of the vehicle‑group. Immunofluorescent double labeling indicated that accumulation of autophagosomes was reduced in the NSP group. Further, post‑SCI treatment with NSP improved the BBB scale and increased the number of anterior horn motor neurons. Together, this study demonstrates that autophagic flux is impaired, meanwhile NSP restores autophagic flux and promotes functional recovery after SCI in rats.

Further Standardization in the Aneurysm Clip: The Effects of Occlusal Depth on the Outcome of Spinal Cord Injury in Rats

STUDY DESIGN

Experimental study.

OBJECTIVE

To evaluate the relationship between clip occlusal depth and functional and histological outcome measures in a rat model of thoracic spinal cord injury (SCI).

SUMMARY OF BACKGROUND DATA

Aneurysm clip compression is a proven model of contusion-compression SCI, but the relationship between clip depth and outcomes in thoracic SCI is unknown.

METHODS

A single aneurysm clip was applied to the spinal cord at thoracic vertebra 10 for 1 minute with an occlusal depth of 2, 6, or 10 mm. The actual compression force was measured using a self-made pulling method. Locomotor function was assessed for 28 days using Basso, Beattie, and Bresnahan (BBB) and inclined plane test (IPT) scores. We then used hematoxylin-eosin and Luxol fast blue staining to histologically quantify cavitation formation, preserved white matter, and preserved grey matter.

RESULTS

Greater occlusal compression depths caused greater actual compression forces and worsened functional and histological recovery. The 2- and 10-mm clip injury groups had significantly different BBB and ITP scores; cavitation, preserved white matter, and preserved grey matter volumes; and actual force measures (P < 0.05).

CONCLUSION

Our findings show that the occlusal depth of clip compression correlates with actual compression force and recovery impairment.

LEVEL OF EVIDENCE

1.

Rodent, large animal and non-human primate models of spinal cord injury

In this narrative review we aimed to assess the usefulness of the different animal models in identifying injury mechanisms and developing therapies for humans suffering from spinal cord injury (SCI). Results obtained from rodent studies are useful but, due to the anatomical, molecular and functional differences, confirmation of these findings in large animals or non-human primates may lead to basic discoveries that cannot be made in rodent models and that are more useful for developing treatment strategies in humans. SCI in dogs can be considered as intermediate between rodent models and human clinical trials, but the primate models could help to develop appropriate methods that might be more relevant to humans. Ideally, an animal model should meet the requirements of availability and repeatability as well as reproduce the anatomical features and the clinical pathological changing process of SCI. An animal model that completely simulates SCI in humans does not exist. The different experimental models of SCI have advantages and disadvantages for investigating the different aspects of lesion development, recovery mechanisms and potential therapeutic interventions. The potential advantages of non-human primate models include genetic similarities, similar caliber/length of the spinal cord as well as biological and physiological responses to injury which are more similar to humans. Among the potential disadvantages, high operating costs, infrastructural requirements and ethical concerns should be considered. The translation from experimental repair strategies to clinical applications needs to be investigated in future carefully designed studies.

Neural Growth Factor Stimulates Proliferation of Spinal Cord Derived-Neural Precursor/Stem Cells

Objective

Recently, regenerative therapies have been used in clinical trials (heart, cartilage, skeletal). We don't make use of these treatments to spinal cord injury (SCI) patients yet, but regenerative therapies are rising interest in recent study about SCI. Neural precursor/stem cell (NPSC) proliferation is a significant event in functional recovery of the central nervous system (CNS). However, brain NPSCs and spinal cord NPSCs (SC-NPSCs) have many differences including gene expression and proliferation. The purpose of this study was to investigate the influence of neural growth factor (NGF) on the proliferation of SC-NPSCs.

Methods

NPSCs (2×10⁴) were suspended in 100 µL of neurobasal medium containing NGF-7S (Sigma-Aldrich) and cultured in a 96-well plate for 12 days. NPSC proliferation was analyzed five times for either concentration of NGF (0.02 and 2 ng/mL). Sixteen rats after SCI were randomly allocated into two groups. In group 1 (SCI-vehicle group, n=8), animals received 1.0 mL of the saline vehicle solution. In group 2 (SCI-NGF group, n=8), the animals received single doses of NGF (Sigma-Aldrich). A dose of 0.02 ng/mL of NGF or normal saline as a vehicle control was intra-thecally injected daily at 24 hour intervals for 7 days. For Immunohistochemistry analysis, rats were sacrificed after one week and the spinal cords were obtained.

Results

The elevation of cell proliferation with 0.02 ng/mL NGF was significant (p<0.05) but was not significant for 2 ng/mL NGF. The optical density was increased in the NGF 0.02 ng/mL group compared to the control group and NGF 2 ng/mL groups. The density of nestin in the SCI-NGF group was significantly increased over the SCI-vehicle group (p<0.05). High power microscopy revealed that the density of nestin in the SCI-NGF group was significantly increased over the SCI-vehicle group.

Conclusion

SC-NPSC proliferation is an important pathway in the functional recovery of SCI. NGF enhances SC-NPSC proliferation in vitro and in vivo. NGF may be a useful option for treatment of SCI patients pending further studies to verify the clinical applicability.

Technique of spinal cord compression induced by inflation of epidural balloon catheter in rabbits (Oryctologus cuniculus): efficient and easy to use model

The most common cause of spinal cord injury are high impact trauma, which often result in some motor impairment, sensory or autonomic a greater or lesser extent in the distal areas the level of trauma. In terms of survival and complications due to sequelae, veterinary patients have a poor prognosis unfavorable. Therefore justified the study of experimental models of spinal cord injury production that could provide more support to research potential treatments for spinal cord injuries in medicine and veterinary medicine. Preclinical studies of acute spinal cord injury require an experimental animal model easily reproducible. The most common experimental animal model is the rat, and several techniques for producing a spinal cord injury. The objective of this study was to describe and evaluate the effectiveness of acute spinal cord injury production technique through inflation of Fogarty(r) catheter using rabbits as an experimental model because it is a species that has fewer conclusive publications and contemplating. The main requirements of a model as low cost, handling convenience, reproducibility and uniformity. The technique was adequate for performing preclinical studies in neuro-traumatology area, effectively leading to degeneration and necrosis of the nervous tissue fostering the emergence of acute paraplegia.

Transplantation of Neural Stem Cells Cultured in Alginate Scaffold for Spinal Cord Injury in Rats

Study Design

This study investigated the effects of transplantation of alginate encapsulated neural stem cells (NSCs) on spinal cord injury in Sprague-Dawley male rats. The neurological functions were assessed for 6 weeks after transplantation along with a histological study and measurement of caspase-3 levels.

Purpose

The aim of this study was to discover whether NSCs cultured in alginate transplantation improve recovery from spinal cord injury.

Overview of Literature

Spinal cord injury is one of the leading causes of disability and it has no effective treatment. Spinal cord injury can also cause sensory impairment. With an impetus on using stem cells therapy in various central nervous system settings, there is an interest in using stem cells for addressing spinal cord injury. Neural stem cell is one type of stem cells that is able to differentiate to all three neural lineages and it shows promise in spinal injury treatment. Furthermore, a number of studies have shown that culturing NSCs in three-dimensional (3D) scaffolds like alginate could enhance neural differentiation.

Methods

The NSCs were isolated from 14-day-old rat embryos. The isolated NSCs were cultured in growth media containing basic fibroblast growth factor and endothelial growth factor. The cells were characterized by differentiating to three neural lineages and they were cultured in an alginate scaffold. After 7 days the cells were encapsulated and transplanted in a rat model of spinal cord injury.

Results

Our data showed that culturing in an alginate 3D scaffold and transplantation of the NSCs could improve neurological outcome in a rat model of spinal cord injury. The inflammation scores and lesion sizes and also the activity of caspase-3 (for apoptosis evaluation) were less in encapsulated neural stem cell transplantation cases.

Conclusions

Transplantation of NSCs that were cultured in an alginate scaffold led to a better clinical and histological outcome for recovery from spinal cord injury in a rat model.

Human bone marrow-derived and umbilical cord-derived mesenchymal stem cells for alleviating neuropathic pain in a spinal cord injury model

BACKGROUND

Stem cell therapy can be used for alleviating the neuropathic pain induced by spinal cord injuries (SCIs). However, survival and differentiation of stem cells following their transplantation vary depending on the host and intrinsic factors of the cell. Therefore, the present study aimed to determine the effect of stem cells derived from bone marrow (BM-MSC) and umbilical cord (UC-MSC) on neuropathic pain relief.

METHODS

A compression model was used to induce SCI in a rat model. A week after SCI, about 1 million cells were transplanted into the spinal cord. Behavioral tests, including motor function recovery, mechanical allodynia, cold allodynia, mechanical hyperalgesia, and thermal hyperalgesia, were carried out every week for 8 weeks after SCI induction. A single unit recording and histological evaluation were then performed.

RESULTS

We show that BM-MSC and UC-MSC transplantations led to improving functional recovery, allodynia, and hyperalgesia. No difference was seen between the two cell groups regarding motor recovery and alleviating the allodynia and hyperalgesia. These cells survived in the tissue at least 8 weeks and prevented cavity formation due to SCI. However, survival rate of UC-MSC was significantly higher than BM-MSC. Electrophysiological evaluations showed that transplantation of UC-MSC brings about better results than BM-MSCs in wind up of wide dynamic range neurons.

CONCLUSIONS

The results of the present study show that BM-MSC and UC-MSC transplantations alleviated the symptoms of neuropathic pain and resulted in subsequent motor recovery after SCI. However, survival rate and electrophysiological findings of UC-MSC were significantly better than BM-MSC.

Evaluation of the effects of specific opioid receptor agonists in a rodent model of spinal cord injury

Objective

The current study aimed to evaluate the contribution(s) of specific opioid receptor systems to the analgesic and detrimental effects of morphine, observed after spinal cord injury in prior studies.

Study Design

We used specific opioid receptor agonists to assess the effects of µ- (DAMGO), δ- (DPDPE), and κ- (GR89696) opioid receptor activation on locomotor (BBB, tapered beam, ladder tests) and sensory (girdle, tactile, and tail-flick tests) recovery in a rodent contusion model (T12). We also tested the contribution of non-classic opioid binding using [+]- morphine.

Methods

First, a dose-response curve for analgesic efficacy was generated for each opioid agonist. Baseline locomotor and sensory reactivity was assessed 24 h after injury. Subjects were then treated with an intrathecal dose of a specific agonist and re-tested after 30 min. To evaluate effects on recovery, subjects were treated with a single dose of an agonist and both locomotor and sensory function were monitored for 21 d.

Results

All agonists for the classic opioid receptors, but not the [+]- morphine enantiomer, produced antinociception at a concentration equivalent to a dose of morphine previously shown to produce strong analgesic effects (0.32 μmol). DAMGO and [+]- morphine did not affect long-term recovery. GR89696, however, significantly undermined recovery of locomotor function at all doses tested.

Conclusions

Based on these data, we hypothesize that the analgesic efficacy of morphine is primarily mediated by binding to the classic μ-opioid receptor. Conversely, the adverse effects of morphine may be linked to activation of the κ-opioid receptor. Ultimately, elucidating the molecular mechanisms underlying the effects of morphine is imperative in order to develop safe and effective pharmacological interventions in a clinical setting.

Setting

USA

Substance P stimulates proliferation of spinal neural stem cells in spinal cord injury via the mitogen-activated protein kinase signaling pathway

BACKGROUND CONTEXT

Substance P (SP) is a neuropeptide that can influence neural stem/progenitor cell (NSPC) proliferation and neurogenesis in the brain. However, we could not find any experimental study that investigates SP action in the spinal cord.

PURPOSE

The aims of our study were to investigate the potential of the neuropeptide SP in promoting the proliferation of spinal cord-derived NSPCs (SC-NSPCs) after spinal cord injury (SCI) and to clarify the roles of the mitogen-activated protein (MAP) kinase signaling pathway in the process.

STUDY DESIGN

This is a randomized animal study.

METHODS

The SC-NSPCs were suspended in 100 μL of a neurobasal medium containing SP (binds neurokinin-1 receptor [NK1R]) or L-703,606 (NK1R antagonist) and cultured in a 96-well plate for 5 days. A cell proliferation assay was performed using a 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay. A cord clipping method was used for the SCI model. Substance P and the NK1R antagonist (L-703,606) were infused intrathecally in SCI and sham models. Neural stem/progenitor cell proliferation was evaluated with immunostaining for bromodeoxyuridine (BrdU) and the immature neural marker nestin. An immunoblotting method was used for evaluating the MAP kinase signaling protein that contains extracellular signal-regulated kinases (ERKs and p38) and β-actin as the control group.

RESULTS

In vitro, SP (0.01-10 μmol/L) increased the proliferation of cultured SC-NSPCs, with a peak increase of 35±2% at the 0.1 μmol/L concentration. Substance P of 0.1 μmol/L continuously increased SC-NSPC proliferation from 6 hours to 5 days, whereas the proliferation decreased from 18% to 98% with L-703,606 (1-10 μM). Intrathecal infusion of SP (1 μmol/L) for 7 days significantly increased the number of proliferating NPSCs (cells positive for both BrdU and nestin) in the spinal cord (by 120±17%, p<.05) in adult rats, but infusion of L-703,606 (10 μmol/L) significantly decreased the post-SCI induction of NPSC proliferation in the spinal cord (by 87±4%). Also, SP stimulates proliferation of SC-NSPCs via the MAP kinase signaling pathway, especially the phosphorylated ERK and phosphorylated p38 proteins. The phosphorylated ERK and phosphorylated p38 protein levels increased with SP (0.1 μmol/L, p<.05).

CONCLUSIONS

These data indicate that SP can promote proliferation of SC-NSPCs in SCI and normal conditions and have important roles in neuronal regeneration after SCI. Also, ERKs and p38 MAP kinases are important signaling proteins in this process.

Neurophysiological monitoring during acute and progressive experimentally induced compression injury of the spinal cord in pigs

PURPOSE

To evaluate the degree of acute or progressive lateral compression needed to cause neurologic injury to the spinal cord assessed by electrophysiological monitoring.

METHODS

In five domestic pigs, the spinal cord was exposed and compressed between T8-T9 roots using a precise compression device. Two sticks placed on both sides of the spinal cord were sequentially brought together (0.5 mm every 2 min), causing progressive spinal cord compression. Acute compression was reproduced by a 2.5-mm displacement of the sticks. Cord-to-cord evoked potentials were obtained with two epidural catheters.

RESULTS

Increasing latency and decreasing amplitude of the evoked potentials were observed after a mean progressive displacement of the sticks of 3.2 ± 0.9 mm, disappearing after a mean displacement of 4.6 ± 1.2 mm. The potential returned after compression removal (16.8 ± 3.2 min). The potentials disappeared immediately after an acute compression of 2.5 ± 0.3 mm, without any sign of recovering after 30 min.

CONCLUSIONS

The experimental model replicates the mechanism of a spinal cord injury caused by medially displaced screws into the spinal canal. The spinal cord had more ability for adaptation to progressive and slow compression than to acute mechanisms.

Stem cell transplantation in neurological diseases: improving effectiveness in animal models

Neurological diseases afflict a growing proportion of the human population. There are two reasons for this: first, the average age of the population (especially in the industrialized world) is increasing, and second, the diagnostic tools to detect these pathologies are now more sophisticated and can be used on a higher percentage of the population. In many cases, neurological disease has a pharmacological treatment which, as in the case of Alzheimer's disease, Parkinson's disease, Epilepsy, and Multiple Sclerosis can reduce the symptoms and slow down the course of the disease but cannot reverse its effects or heal the patient. In the last two decades the transplantation approach, by means of stem cells of different origin, has been suggested for the treatment of neurological diseases. The choice of slightly different animal models and the differences in methods of stem cell preparation make it difficult to compare the results of transplantation experiments. Moreover, the translation of these results into clinical trials with human subjects is difficult and has so far met with little success. This review seeks to discuss the reasons for these difficulties by considering the differences between human and animal cells (including isolation, handling and transplantation) and between the human disease model and the animal disease model.

A meta-analysis of the motion function through the therapy of spinal cord injury with intravenous transplantation of bone marrow mesenchymal stem cells in rats

Background

To compare the efficacy of the therapy of spinal cord injury with intravenous transplantation of bone marrow mesenchymal stem cells (BMSCs) by Meta-analysis.

Methods

Studies of the BBB scores after intravenous transplantation of BMSCs were searched out from Pubmed, SCI, Cochrane Library, Chinese journal full-text database, China Biology Medicinedisc and Wanfang data-base and analyzed by Review Manager 5.2.5.

Results

Nine randomized controlled animal trials were selected with 235 rats enrolled. The studies are divided to different subgroups by different models of SCI and different time to transplantion. The results of Meta-analysis in different subgroups both indicated that the rats of experimental group (BMSCs group) got better BBB scores than control group at 1, 3 and over 5 weeks after intravenous transplantation of BMSCs with significant differences. The heterogeneity between impacted injury model and oppressed injury model subgroups decreased with the passage of time (I² = 75.8%, 39.7%, 0%). No heterogeneity was found between 3 d and 7 d subgroups.

Conclusion

The intravenous transplantation of BMSCs is an efficient way to cure spinal cord injury, which can improve the motor function of rats. The therapeutic window is wide.

SCO-spondin derived peptide NX210 induces neuroprotection in vitro and promotes fiber regrowth and functional recovery after spinal cord injury

In mammals, the limited regenerating potential of the central nervous system (CNS) in adults contrasts with the plasticity of the embryonic and perinatal periods. SCO (subcommissural organ)-spondin is a protein secreted early by the developing central nervous system, potentially involved in the development of commissural fibers. SCO-spondin stimulates neuronal differentiation and neurite growth in vitro. NX210 oligopeptide was designed from SCO-spondin's specific thrombospondin type 1 repeat (TSR) sequences that support the main neurogenic properties of the molecule. The objective of this work was to assess the neuroprotective and neuroregenerative properties of NX210 in vitro and in vivo for the treatment of spinal cord injury (SCI). In vitro studies were carried out on the B104 neuroblastoma cell line demonstrating neuroprotection by the resistance to oxidative damage using hydrogen peroxide and the measure of cell viability by metabolic activity. In vivo studies were performed in two rat models of SCI: (1) a model of aspiration of dorsal funiculi followed by the insertion of a collagen tube in situ to limit collateral sprouting; white matter regeneration was assessed using neurofilament immunostaining; (2) a rat spinal cord contusion model to assess functional recovery using BBB scale and reflex testing. We demonstrate for the first time that NX210 (a) provides neuroprotection to oxidative stress in the B104 neuroblastoma cells, (b) stimulates axonal regrowth in longitudinally oriented neofibers in the aspiration model of SCI and (c) significantly improves functional recovery in the contusive model of SCI.

Characterization of vascular disruption and blood-spinal cord barrier permeability following traumatic spinal cord injury

Significant vascular changes occur subsequent to spinal cord injury (SCI), which contribute to progressive pathophysiology. In the present study, we used female Wistar rats (300-350 g) and a 35-g clip-compression injury at T6 to T7 to characterize the spatial and temporal vascular changes that ensue post-SCI. Before sacrifice, animals were injected with vascular tracing dyes (2% Evans Blue (EB) or fluorescein isothiocyanate/Lycopersicon esculentum agglutinin [FITC-LEA]) to assess blood-spinal cord barrier (BSCB) integrity or vascular architecture, respectively. Spectrophotometry of EB tissue showed maximal BSCB disruption at 24 h postinjury, with significant disruption observed until 5 days postinjury (p<0.01). FITC-LEA-identified functional vasculature was dramatically reduced by 24 h. Similarly, RECA-1 immunohistochemistry showed a significant decrease in the number of vessels at 24 h postinjury, compared to uninjured animals (p<0.01), with slight increases in endogenous revascularization by 10 days postinjury. White versus gray matter (GM) quantification showed that GM vessels are more susceptible to SCI. Finally, we observed an endogenous angiogenic response between 3 and 7 days postinjury: maximal endothelial cell proliferation was observed at day 5. These data indicate that BSCB disruption and endogenous revascularization occur at specific time points after injury, which may be important for developing effective therapeutic interventions for SCI.

A highly reproducible mouse model of compression spinal cord injury

Experimental spinal cord injury (SCI) can maintain the continuity of the spinal cord, as in the contusion (e.g., weight-fall) or compression models, or not, when there is a partial or a complete transection. The majority of acute human SCI is not followed by complete transection, but there is a combination of contusion, compression, and possibly partial transection. The method described here is a compressive mouse model that presents a combination of contusion and compression components and has many facilities in its execution. This lesion was established by our group and represents a simple, reliable, and inexpensive clip compression model with functional and morphological reproducibility. In this chapter we describe, step by step, the protocol of this experimental SCI.

Functional effect of mouse embryonic stem cell implantation after spinal cord injury

We transplanted mouse embryonic stem cells (mESCs) to improve functional loss in a rat model of clip-compression spinal cord injury (SCI). The mouse embryonic stem cells were transplanted to injured cord 7 days after injury. We include minimizing the progression of secondary injury, manipulating the neuroinhibitory environment of the spinal cord, replacing lost tissue with transplanted cells and substantial improvement of motor. A number of potential approaches optimize functional recovery after spinal cord injury. We review the application of stem cell transplantation to the spinal cord, emphasizing the use of embryonic stem cells for reconstruction of spinal cord injury. Thus, this study provides strong evidence to support that transplantation of mESC could improve functional recovery after SCI.

A standardized method to create peripheral nerve injury in dogs using an automatic non-serrated forceps

This study describes a method that not only generates an automatic and standardized crush injury in the skull base, but also provides investigators with the option to choose from a range of varying pressure levels. We designed an automatic, non-serrated forceps that exerts a varying force of 0 to 100 g and lasts for a defined period of 0 to 60 seconds. This device was then used to generate a crush injury to the right oculomotor nerve of dogs with a force of 10 g for 15 seconds, resulting in a deficit in the pupil-light reflex and ptosis. Further testing of our model with Toluidine-blue staining demonstrated that, at 2 weeks post-surgery disordered oculomotor nerve fibers, axonal loss, and a thinner than normal myelin sheath were visible. Electrophysiological examination showed occasional spontaneous potentials. Together, these data verified that the model for oculomotor nerve injury was successful, and that the forceps we designed can be used to establish standard mechanical injury models of peripheral nerves.

The neuroprotective effect of treatment of valproic Acid in acute spinal cord injury

OBJECTIVE

Valproic acid (VPA), as known as histone deacetylase inhibitor, has neuroprotective effects. This study investigated the histological changes and functional recovery from spinal cord injury (SCI) associated with VPA treatment in a rat model.

METHODS

Locomotor function was assessed according to the Basso-Beattie-Bresnahan scale for 2 weeks in rats after receiving twice daily intraperitoneal injections of 200 mg/kg VPA or the equivalent volume of normal saline for 7 days following SCI. The injured spinal cord was then examined histologically, including quantification of cavitation.

RESULTS

Basso-Beattie-Bresnahan scale scores in rats receiving VPA were significantly higher than in the saline group (p<0.05). The cavity volume in the VPA group was significantly reduced compared with the control (saline-injected) group (p<0.05). The level of histone acetylation recovered in the VPA group, while it was significantly decreased in the control rats (p<0.05). The macrophage level was significantly decreased in the VPA group (p<0.05).

CONCLUSION

VPA influences the restoration of hyperacetylation and reduction of the inflammatory reaction resulting from SCI, and is effective for histology and motor function recovery.

Sulphoraphane enhances aquaporin-4 expression and decreases spinal cord oedema following spinal cord injury

BACKGROUND

Aquaporin-4 (AQP4) is a water channel protein and it is an important determinant of outcome after brain injury. Sulphoraphane (SFN) increases AQP4 levels with reduction of brain oedema at 3 days post-traumatic brain injury. However, little is known about the effect of SFN on AQP4 expression and oedema after spinal cord injury (SCI).

METHODS AND PROCEDURES

The present study used a murine SCI model induced by compression injury. AQP4 protein level and mRNA level were detected by Western blot and by RT-PCR at 48 hours after SCI, respectively. In addition, immunohistochemical study was used to show AQP4 expression in the spinal cord segments and water content of the spinal cord segments were measured by wet?:?dry weight ratio.

MAIN OUTCOMES AND RESULTS

This study shows that AQP4 level was decreased in the injured spinal cord segments at 48 hours following SCI. Post-injury administration of SFN increased AQP4 levels, which was accompanied by a significant reduction in spinal cord segment oedema at 48 hours post-injury.

CONCLUSION

These findings suggest that the reduction of spinal cord oedema in response to SFN administration could be due, in part, to water clearance by AQP4 from the injured spinal cord segments.

In vivo longitudinal MRI and behavioral studies in experimental spinal cord injury

Comprehensive in vivo longitudinal studies that include multi-modal magnetic resonance imaging (MRI) and a battery of behavioral assays to assess functional outcome were performed at multiple time points up to 56 days post-traumatic spinal cord injury (SCI) in rodents. The MRI studies included high-resolution structural imaging for lesion volumetry, and diffusion tensor imaging (DTI) for probing the white matter integrity. The behavioral assays included open-field locomotion, grid walking, inclined plane, computerized activity box performance, and von Frey filament tests. Additionally, end-point histology was assessed for correlation with both the MRI and behavioral data. The temporal patterns of the lesions were documented on structural MRI. DTI studies showed significant changes in white matter that is proximal to the injury epicenter and persisted to day 56. White matter in regions up to 1 cm away from the injury epicenter that appeared normal on conventional MRI also exhibited changes that were indicative of tissue damage, suggesting that DTI is a more sensitive measure of the evolving injury. Correlations between DTI and histology after SCI could not be firmly established, suggesting that injury causes complex pathological changes in multiple tissue components that affect the DTI measures. Histological evidence confirmed a significant decrease in myelin and oligodendrocyte presence 56 days post-SCI. Multiple assays to evaluate aspects of functional recovery correlated with histology and DTI measures, suggesting that damage to specific white matter tracts can be assessed and tracked longitudinally after SCI.

Intrathecal morphine attenuates recovery of function after a spinal cord injury

Prior work has shown that a high dose (20 mg/kg) of systemic morphine, required to produce significant analgesia in the acute phase of a contusion injury, undermines the long-term health of treated subjects and increases lesion size. Moreover, a single dose of systemic morphine in the early stage of injury (24 h post-injury) led to symptoms of neuropathic pain 3 weeks later, in the chronic phase. The present study examines the locus of the effects using intrathecal morphine administration. Subjects were treated with one of three doses (0, 30, or 90 microg) of intrathecal morphine 24 h after a moderate contusion injury. The 90-microg dose produced significant analgesia when subjects were exposed to noxious stimuli (thermal and incremented shock) below the level of injury. Yet, despite analgesic efficacy, intrathecal morphine significantly attenuated the recovery of locomotor function and increased lesion size rostral to the injury site. A single dose of 30 or 90 microg of intrathecal morphine also decreased weight gain, and more than doubled the incidence of mortality and autophagia when compared to vehicle-treated controls. Morphine is one of the most effective pharmacological agents for the treatment of neuropathic pain and, therefore, is indispensable for the spinally injured. Treatment can, however, adversely affect the recovery process. A morphine-induced attenuation of recovery may result from increases in immune cell activation and, subsequently, pro-inflammatory cytokine concentrations in the contused spinal cord.

Immunohistochemical study of cathepsin D in the spinal cords of rats with clip compression injury

This study examined the temporal expression of cathepsin D protein and its cellular localization in the spinal cords of rats after a clip compression injury to determine the involvement of cathepsin D in spinal cord injury (SCI). Western blot analysis showed a significant increase in the approximately 31-kDa active form of cathepsin D on days 4 and 7 after the SCI, while the level of the approximately 44-kDa inactive form remained relatively unchanged. Immunohistochemistry revealed cathepsin D with constitutive localization in most neurons and some gliocytes in the normal spinal cord to be intensely immuno-detected primarily in CD68-positive activated macrophages/microglia in the SCI lesions. Overall, these findings suggest that cathepsin D plays an important role in the phagocytosis and lysosomal activation of macrophages/microglia during the central nervous system inflammation caused by trauma.

Clip compression model is useful for thoracic spinal cord injuries: histologic and functional correlates

STUDY DESIGN

Experimental investigation of an acute thoracic spinal cord injury model in rats involving acute clip compression that simulates human injury.

OBJECTIVE

To assess the dose-response of this model for the relationship between the force of injury on the rat thoracic spinal cord and histological and functional outcome measures.

SUMMARY OF BACKGROUND DATA

Acute extradural clip compression injury has been a reliable model for producing acute experimental cervical spinal cord injury; however, this model has not been formally evaluated with dose-response curves for acute injury of the thoracic spinal cord.

METHODS

After laminectomy at T2 in Sprague-Dawley rats, a modified aneurysm clip exerting a closing force of 20, 26, or 35 g was applied extradurally around the spinal cord at T2, and then rapidly released with cord compression persisting for 1 minute. These forces were selected to simulate acute compression injuries of mild to moderate, moderate, and moderate to severe degrees, respectively (n = 8/group). Motor activity was assessed weekly for 4 weeks with the Basso, Beattie, and Bresnahan (BBB) open field locomotor test. The injured spinal cord was then examined histologically including quantification of cavitation.

RESULTS

A significant main effect was observed for clip force and BBB score (F(2,20) = 5.42, P = 0.013). For 4 weeks after injury, the BBB scores for the 20 g and 35 g clip injury groups were significantly different (P < 0.05). The cavitation volume at 4 weeks was directly proportional to the severity of injury: the 20 g group had significantly smaller cavities than the 35 g group (P < 0.05), and the cavitation volume correlated with the BBB scores.

CONCLUSION

The rat thoracic cord clip compression model is a reproducible, clinically relevant spinal cord injury model. This is the first time that the force of clip compression injury in the rat thoracic cord has been correlated with both functional and histologic outcome measures.

Establishment of a canine spinal cord injury model induced by epidural balloon compression

A model that provides reproducible, submaximal yet sufficient spinal cord injury is needed to allow experiments leading to development of therapeutic techniques and prediction of clinical outcome to be conducted. This study describes an experimental model for spinal cord injury that uses three different volumes of balloon inflation and durations of compression to create a controlled gradation outcome in adult dogs. Twenty-seven mongrel dogs were used for this study. A 3-french embolectomy catheter was inserted into the epidural space through a left hemilaminectomy hole at the L₄ vertebral arch. Balloons were then inflated with 50, 100, or 150 µl of a contrast agent at the L1 level for 6, 12, or 24 h and spinal canal occlusion (SCO) measured using computed tomography. Olby score was used to evaluate the extent of spinal cord injury and a histopathologic examination was conducted 1 week after surgery. The SCO of the 50, 100, and 150 µl inflations was 22-46%, 51-70%, and 75-89%, respectively (p < 0.05). Olby scores were diminished significantly by a combination of the level of SCO and duration of inflation in all groups. Olby scores in the groups of 150 µl-12 h, 150 µl-24 h, and 100 µl-24 h were 0.5, 0, and 1.7, respectively. Based on these results, a SCO > 50% for 24 h, and > 75% for 12 h induces paraplegia up to a week after spinal cord injury.

The impact of morphine after a spinal cord injury

Nociceptive stimulation, at an intensity that elicits pain-related behavior, attenuates recovery of locomotor and bladder functions, and increases tissue loss after a contusion injury. These data imply that nociceptive input (e.g., from tissue damage) can enhance the loss of function after injury, and that potential clinical treatments, such as pretreatment with an analgesic, may protect the damaged system from further secondary injury. The current study examined this hypothesis and showed that a potential treatment (morphine) did not have a protective effect. In fact, morphine appeared to exacerbate the effects of nociceptive stimulation. Experiment 1 showed that after spinal cord injury 20mg/kg of systemic morphine was necessary to induce strong antinociception and block behavioral reactivity to shock treatment, a dose that was much higher than that needed for sham controls. In Experiment 2, contused rats were given one of three doses of morphine (Vehicle, 10, 20mg/kg) prior to exposure to uncontrollable electrical stimulation or restraint alone. Despite decreasing nociceptive reactivity, morphine did not attenuate the long-term consequences of shock. Rats treated with morphine and shock had higher mortality rates, and displayed allodynic responses to innocuous sensory stimuli three weeks later. Independent of shock, morphine per se undermined recovery of sensory function. Rats treated with morphine alone also had significantly larger lesions than those treated with saline. These results suggest that nociceptive stimulation affects recovery despite a blockade of pain-elicited behavior. The results are clinically important because they suggest that opiate treatment may adversely affect the recovery of function after injury.

Rat Models of Traumatic Spinal Cord Injury to Assess Motor Recovery

Devastating motor, sensory, and autonomic dysfunctions render long-term personal hardships to the survivors of traumatic spinal cord injury (SCI). The suffering also extends to the survivors' families and friends, who endure emotional, physical, and financial burdens in providing for necessary surgeries, care, and rehabilitation. After the primary mechanical SCI, there is a complex secondary injury cascade that leads to the progressive death of otherwise potentially viable axons and cells and that impairs endogenous recovery processes. Investigations of possible cures and of ways to alleviate the hardships of traumatic SCI include those of interventions that attenuate or overcome the secondary injury cascade, enhance the endogenous repair mechanisms, regenerate axons, replace lost cells, and rehabilitate. These investigations have led to the creation of laboratory animal models of the different types of traumatic human SCI and components of the secondary injury cascade. However, no particular model completely addresses all aspects of traumatic SCI. In this article, we describe adult rat SCI models and the motor, and in some cases sensory and autonomic, deficits that each produces. Importantly, as researchers in this area move toward clinical trials to alleviate the hardships of traumatic SCI, there is a need for standardized small and large animal SCI models as well as quantitative behavioral and electrophysiological assessments of their outcomes so that investigators testing various interventions can directly compare their results and correlate them with the molecular, biochemical, and histological alterations.

The effect of long-term reduction of aortic blood flow on spinal cord gray matter in the rabbit. Histochemical study of NADPH-diaphorase

1. The aim of this work was to study the influence of reduced aortic blood flow on NADPH-diaphorase (NADPH-d) staining in the gray matter of L4-S3 spinal cord segments. 2. Surgery was performed on the abdominal aorta of the rabbit. Spinal cord ischemia was introduced by infrarenal aortic constriction to 30% from the normal blood flow. Animals were allowed to survive 1 week, 1 month and 3 months after surgery. Neurological outcome was studied in relation to the duration of aortic occlusion. The NADPH-d histochemistry was used for the visualisation of spinal cord sections. 3. The most affected area of the spinal cord was pericentral region, and slight changes were seen in the NADPH-d activities of both dorsal and ventral horns. One week after surgery, NADPH-d positive pericentral neurons were almost unchanged in their shape and intensity of staining, the only difference was seen in slightly increased staining of the background around the central canal. One month following surgery neurons exhibited shrinkage or were swollen, NADPH-d staining was less intensive in the pericentral zone and positively stained vessels were present. 4. Three months of ischemia influenced the NADPH-d activity: (a) In the pericentral region were seen intensively NADPH-d stained neurons almost normal in shape of their bodies but with shortened processes or without them; (b) NADPH-d staining of neuropil was greatly enhanced mostly around the central canal and in the dorsal commissure; (c) Numerous vessels were present in the pericentral zone and in the location of the ventral horn. 5. It can be concluded that the reduction of blood flow in the abdominal aorta makes most changes in the pericentral region of the rabbit spinal cord. Increased NADPH-d staining of neuropil and the presence of positively stained vessels reflect increased NADPH-d/NOS production in the spinal cord gray matter after long-term incomplete aortic occlusion.

Optimization of a mouse locomotor rating system to evaluate compression-induced spinal cord injury: correlation of locomotor and morphological injury indices

Object

Due to the usefulness of mouse genetics, there is a need to improve procedures for producing and assessing spinal cord injury (SCI) in mice. The authors describe an improved locomotor scoring system for evaluating SCI. The modified Basso-Beattie-Bresnahan (mBBB) scoring system for mice is compared with existing procedures as well as histological SCI criteria.

Methods

Mice were subjected to SCI by placing a weight on the cord at T-12 for 5 to 15 minutes after laminectomy to produce spinal cord ischemia. Injury was assessed using mBBB scoring that incorporates elements of the rat BBB and the mouse motor function scoring systems that are best suited for precisely assessing mouse SCI. The mBBB score was found to be more discriminating than the inclined plane test, and in the authors’ laboratory it had a significantly lower coefficient of variation than the Basso mouse scale score. The mBBB score is well correlated with sparing of white matter as assessed by eriochrome cyanine staining of myelin.

Conclusions

Weight placement at T-12 in the mouse causes reproducible SCI. A new mBBB scoring system is useful for accurately assessing locomotor dysfunction following SCI in mice and is well correlated with histological assessment of spinal cord white matter.

A new device for experimental modeling of central nervous system injuries

This article introduces a new device for inducing central nerve system injuries in experimental studies with animal models. The construction of the device is based on a commercially available servo-drive system incorporating the latest instrumentation technology and software developed in house to control the motion profile of the injury bit. The software, which is available upon request from the author, was designed such that the user can set the mechanical properties of the motion. For the purpose of quality control, tests were described and performed to assess the ability of the device to reproduce the prescribed motion when operated repetitively under the same set of parameters. Experiments were then conducted on animals to injure mouse brain and rat spinal cord. Following the injuries, in vivo magnetic resonance imaging was performed on the animals to depict the pathologies of the resulting injuries in the corresponding neuronal tissues. Rat spinal cords injured mildly and severely were followed longitudinally for up to 28 days postinjury. The neurobehaviors of the animals evaluated using locomotor rating scores indicated the ability of the device to produce repeatable graded injuries.

Upregulation of CD44 expression in the spinal cords of rats with clip compression injury

The expression of the extracellular matrix phosphoglycoprotein CD44 after compression injury of the spinal cord was examined in rats. Western blot analysis of tissues harvested on days 0 (sham), 1, 4 and 7 post-injury showed significant increases in CD44 expression from 1 to 7 days after compression injury compared to sham-operated controls. Immunohistochemistry revealed that CD44 was constitutively expressed in some astrocytes in sham-operated controls. At days 4-7 post-injury, CD44 was intensely expressed in astrocytes in the periphery of lesions, and in myelin sheaths, vessels, and the majority of inflammatory cells including macrophages in core lesions. The finding that expression of CD44 was upregulated after spinal cord injury suggests that CD44 contributes to cell adhesion and glial cell attraction during the early stages after spinal cord injury, and may thus promote remodeling of injured spinal cords.

Immunohistochemical Study of Osteopontin in the Spinal Cords of Rats with Clip Compression Injury

Expression of osteopontin (OPN) was investigated in the spinal cords of rats with clip compression injury. Western blot analysis demonstrated that OPN protein increased significantly in the spinal cord during the early stages after injury. The increased expression of OPN was partially paralleled by that of proliferating cell nuclear antigen (PCNA). Immunohistochemical staining showed that OPN was expressed in proliferating activated microglia/macrophages in core lesions and in some astrocytes at the periphery of lesions. These results indicate that expression of OPN protein increases mainly in activated microglia/macrophages after spinal cord injury, suggesting that OPN is related to cell proliferation during the early stages after injury, probably leading to tissue remodeling.

Upregulation of phospholipase D1 in the spinal cords of rats with clip compression injury

This study examined phospholipase D 1 (PLD1) expression in the central nervous system following clip compression spinal cord injury (SCI) in Sprague-Dawley rats. After inducing SCI with a vascular clip, the expression of PLD1 in the affected spinal cord was analyzed by Western blot and immunohistochemistry. Western blot analysis showed that the expression of PLD1 gradually increased in the spinal cord on days 0.5, 1, 2, and 4 post injury. Immunohistochemistry showed that some cells, including neurons, astrocytes, and some inflammatory cells, were positive for PLD1 in the lesions at days 1 and 2 post injury. At day 4, the number of PLD1-positive cells in SCI lesions increased, largely matching the increases in ED1-positive macrophages and glial fibrillary acidic protein-positive astrocytes. At this time, macrophages expressed proliferating cell nuclear antigen in addition to PLD1. These results suggest that PLD1 expression is increased in injured spinal cords, and might be involved in the activation and proliferation of macrophages and astrocytes in SCI.

Overexpression of SOD1 protects vulnerable motor neurons after spinal cord injury by attenuating mitochondrial cytochrome c release

Defective Cu,Zn-superoxide dismutase (SOD1) is responsible for some types of amyotrophic lateral sclerosis, and ventral horn motor neurons (VMN) have been shown to die through a mitochondria-dependent apoptotic pathway after chronic exposure to high levels of reactive oxygen species (ROS). VMN are also selectively vulnerable to mild spinal cord injury (SCI); however, the involvement of SOD1, ROS, and apoptosis in their death has not been clarified. Mild compression SCI was induced in SOD1-overexpressing transgenic rats and wild-type littermates. Superoxide production, mitochondrial release of cytochrome c, and activation of caspase-9 were examined, and apoptotic DNA injury was also characterized. In the wild-type animals, increased superoxide production, mitochondrial release of cytochrome c, and cleaved caspase-9 were observed exclusively in VMN after SCI. Subsequently, a majority of VMN (75%) selectively underwent delayed apoptotic cell death. Transgenic animals showed less superoxide production, mitochondrial cytochrome c release, and caspase-9 activation, resulting in death of only 45% of the VMN. These results suggest that the ROS-initiated mitochondrial signaling pathway possibly plays a pivotal role in apoptotic VMN death after SCI and that increased levels of SOD1 in VMN reduce oxidative stress, thereby attenuating the activation of the pathway and delayed cell death.

The heme oxygenase system and cellular defense mechanisms. Do HO-1 and HO-2 have different functions?

Heme oxygenase isozymes, HO-1, HO-2 and HO-3, are HSP32 protein cognates, with a known function of catalyzing the isomer specific oxidation of the heme molecule, including that of NO synthase. Unknown until recent years was that the system is a central component of the cellular defense mechanisms; this can be attributed to a combination of many factors. In biological systems HO activity is responsible for production of equimolar amounts of CO, biliverdin and free Fe. The serine/threonine kinase, biliverdin reductase, catalyzes reduction of biliverdin to bilirubin. Bilirubin is a potent antioxidant and CO is a signal molecule. Although both active HO isozymes catalyze the same reaction, HO-1 and HO-2 may function in a rather distinct fashion in protection against tissue injury. HO-1 is the stress responsive cognate that is rapidly induced by free and stable radicals as well as by hypoxia. Supra induction of HO-1 completely protects ischemic kidney against tissue pathology. This involves rapid inactivation of the pro-oxidant heme of denatured hemoproteins and converting it to bilirubin and CO. In the case of severe tissue injury, such as compression injury, HO-1 is induced and colocalizes with cGMP and pro-apoptotic oncogenes. HO-2, which is the constitutive form, in addition to maintaining cell heme homeostasis, inactivates NO derived radicals. The isozyme binds the free radical at its "heme regulatory motifs" and is "suicide" inactivated at the protein and transcript levels. Data are shown that provide evidence for role of the HO system in the cellular defense mechanism against free radical-mediated tissue damage, and are consistent with the forwarded concept that HO isozymes have common, as well as distinct, roles in cellular defense mechanisms.

A simple and reproducible model of spinal cord injury induced by epidural balloon inflation in the rat

This paper describes a modification of a balloon-compression technique to produce spinal cord injury in adult rats. A 2-French Fogarty catheter is inserted into the dorsal epidural space through a small hole made in T10 vertebral arch, advanced cranially to T8-9 spinal level, and inflated for 5 min. Spinal cord damage is graded by increasing the volume of saline used to inflate the balloon. Quantitative neurological and histopathological outcomes are presented with three different volumes (10, 15, and 20 microl of saline) to characterize the gradation of injury. Volume of 15 microl produced complete paraplegia followed by gradual recovery, finally reaching approximately the middle of the scale used to quantitate the locomotor performance. With these animals, after 4 weeks, the center of the lesion shows complete loss of grey matter and partial sparing of the white matter. We conclude that 15 microl volume produced submaximal injury that will be useful for studying the pathophysiology and effects of protective therapies with this compression-injury model.

Site of injury-directed induction of heme oxygenase-1 and -2 in experimental spinal cord injury: differential functions in neuronal defense mechanisms?

The heme oxygenase (HO) isozymes catalyze oxidation of the heme molecule to biliverdin and carbon monoxide (CO) with the release of chelated iron. Presently, we have defined, for the first time, propensity for site of injury-directed induction of isozymes--the stress-inducible isozyme, HO-1, responds distal (below) and the glucocorticoid (GC)-inducible HO-2 responds proximal (above) to the site of injury. We have also shown that reactive iron (Fe3+) and cGMP staining spatially resemble that of HO-1; which, in turn, colocalizes in motor neurons with transcription factors: Fas-associated protein containing death domain (FADD), tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) and p53. Spinal cord injury (SCI) was inflicted by clip compression for 30 min, and analyses were carried out after 4 h or 16 h. When compared with spinal cord segments proximal to the site of injury, northern blot analysis showed remarkably higher levels of HO-1 mRNA distal (below) to the site of injury at both time points. In contrast, HO-2 mRNA levels were elevated proximal (above) to the site of injury and more prominently at 16 h post SCI. Immunohistochemical analyses were carried out using 2 x 5 mm segments above and below the compression site. When compared with segments above the site of injury, the intensity of HO-1 immunostaining and the number of HO-1 positive neurons in the ventral horn motor neurons were prominently increased in segments below the injury. Western blot analysis confirmed the observations. HO-2 protein was mapped to the ventral horn motor neurons, oligodendrocytes, the Clarke's nucleus neurons and the ependymal cells. When compared with segments below the site of injury, neuronal HO-2 staining intensity was increased above the site of injury, and most notably at 16 h. These observations were also confirmed by western blotting and HO activity measurements. Tissue Fe3+ and cGMP staining were increased and prominently mapped below the site of injury, where cGMP colocalized with HO-1 in the nucleus of the motor neurons. Also, a site of injury-directed pattern of induction of FADD, TRAIL, and p53 immunoreactivity, and a widespread colocalization of the oncogenes with HO-1 protein, were found within motor neurons below the level of injury. We forward the hypothesis that HO-1 and HO-2 have different roles in the defense mechanisms of the injured nervous system. We hypothesize that HO-1 protects against further damage by contributing to controlled cell death through their intrinsic suicide program, while HO-2 is involved in suppression of inflammatory response by NO derived radicals.

Efficient testing of motor function in spinal cord injured rats

In experimental spinal cord injury studies, animal models are widely used to examine anatomical and functional changes after different treatments and lesion types. A variety of behavioral paradigms exists in the literature, but definitions and criteria for motor performance vary considerably. In this study, we examined the outcome and relation of tests such as the BBB open field locomotion score, footprint analysis, kinematic analysis, placing response, grid walk and narrow beam crossing following two different lesion types. The information obtained was used to design an efficient and reliable testing strategy, which includes a broad spectrum of parameters to enhance sensitivity. This approach should help to standardize modular testing procedures across different laboratories working on spinal cord injury.

Spatial and temporal evolution of hemorrhage in the hyperacute phase of experimental spinal cord injury: in vivo magnetic resonance imaging

To follow the spatial and temporal evolution of hemorrhage, in vivo MRI studies of experimental spinal cord injury (SCI) were performed on 17 rats in the very acute phase (hyperacute), starting as early as 9 min and continued up to 400 min posttrauma. Axial MR images were processed slice by slice over a 21 mm length around the epicenter of the injury. The data were analyzed statistically and fitted to an empirically derived function to characterize the spatial and temporal evolution of hemorrhage. The results indicated that 1) the initial hemorrhage in the very early phase of the injury area covered 12.5% of the total cord area and subsequently increased with a time constant of 700 min, 2) a major portion of the hemorrhage was concentrated spatially within the 4 mm distance from the epicenter, 3) the volume of hemorrhage normalized to its initial value increased linearly at a rate of approximately 0.0015 min(-1), and 4) edema was observed at the gray- and white-matter junction as early as 12 min postinjury. In general, edema appeared to be focal and scattered in this phase of the injury, which made its quantification unreliable on MRI.

The fate of the compressed deformed spinal cord after decompressive surgery: MR imaging and histopathological findings in experimental studies

The authors conducted a study in which they applied the spinal cord compression-decompression model in rabbits to investigate the morphological changes and histopathological findings in the deformed spinal cord over a long-term period after performing decompressive surgery. Throughout the experimental period, mangnetic resonance (MR) images were obtained frequently; after obtaining a final MR image, the spinal cord was dissected and underwent histological examination. Immediately after decompressive surgery, axial T1-wieighted MR imaging revealed an increase in the cross-sectional area of the spinal cord during the 1st and 2nd weeks. The spinal cord area achieved a peak at an average of 5.9 weeks after decompressive surgery, when it displayed isointensity on T1- and high-intensity on T2-weighted images. The main histological findings were spongy changes in the white matter, which persisted for 4 months postsurgery. There was a significant correlation between the presurgical spinal cord area and the postsurgical decreased number of motor neuron cells. Based on the MR imaging and histopathological studies, although the deformed spinal cord that underwent compression for 3 months was immediately restored morphologically after decompressive surgery, the change in quality in the spinal cord persisted at least 4 months.