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

Evaluating the anti-neuropathic effects of the thymol-loaded nanofibrous scaffold in a rat model of spinal cord injury

Background

Spinal cord injury (SCI) is a debilitating condition characterized by partial or complete loss of motor and sensory function caused by mechanical trauma to the spinal cord. Novel therapeutic approaches are continuously explored to enhance spinal cord regeneration and functional recovery.

Purpose

In this study, we investigated the efficacy of the poly(vinyl alcohol) and chitosan (PVA/CS) scaffold loaded with different thymol concentrations (5, 10, and 15 wt%) in a rat compression model for SCI treatment compare to other (e.g., thymol and scaffold) control groups.

Results and discussion

The thymol-loaded scaffold exhibited a smooth surface and a three-dimensional nanofibrous structure with nanoscale diameter. The conducted analyses verified the successful incorporation of thymol into the scaffold and its high water absorption, porosity, and wettability attributes. Behavioral assessment of functional recovery showed improving sensory and locomotor impairment. Furthermore, histopathological examinations indicated the regenerative potential of the thymol-loaded nanofiber scaffold, by neuronal survival.

Conclusion

Therefore, these findings suggest that the thymol-loaded nanofibrous scaffolds have promising pharmacological activities for alleviating neuropathic pain and addressing complications induced by SCI.

Modulation of Gonadotropin-Releasing Hormone Receptor Improves Voiding Hyperreflexia and Detrusor Sphincter Dyssynergia in Male Rats With Severe Spinal Cord Injury

AIMS

The objective of the current study was to test the beneficial effects of a GnRH analog, leuprolide acetate (LA), over the urinary function in a rat model of lower urinary dysfunction by cystometry and electromyography in fully awake conditions in males with and without SCI.

METHODS

Male Wistar rats that underwent spinal cord compression at T10 level were divided into three groups consisting of (1) SHAM, (2) SCI, and (3) SCI + LA 10 μg/kg i.m. (once a day for 3 days, then every 72 h until complete 13 doses). We then conducted awake cystometrograms and electromyograms of the external urethral sphincter (EUS) and compared urodynamic parameters between the three groups. The expression of Gonadotropin-releasing hormone receptor (GnRH-R) on the urinary bladder was evaluated and compared among three groups by real-time polymerase chain reaction (qPCR). Additionally, the hind limb movements related to micturition were analyzed.

RESULTS

SCI induces detrusor sphincter dyssynergia, urinary malfunction, increased mRNA expression for the GnRH receptor in the urinary bladder in injured rats and increased hind limb movements related to micturition. Meanwhile, treatment with LA partially reverses these changes.

CONCLUSION

The potential of LA for the treatment of urinary disorders associated with SCI opens the way to a new therapeutic option for individuals with SCI who would like to have an impact on their daily lives.

Unveiling the effects of Rosa canina oligosaccharide liposome on neuropathic pain and motor dysfunction following spinal cord injury in rats: relevance to its antioxidative effects

Background

Spinal cord injury (SCI) is a leading cause of sensorimotor disorders, impacting millions of people globally. The absence of effective treatments and the side effects of existing medications highlight the need for innovative research into new therapeutic compounds.

Purpose

Given the critical role of oxidative stress in the development of SCI and the antioxidant properties of oligosaccharides in other neurological disorders, this study focuses on the role of oxidative stress in SCI and explores the potential of a novel oligosaccharide nanoformulation derived from Rosa canina (Oligo-L).

Materials and methods

Oligo-L was formulated using soy lecithin as the phospholipid and the characterization included size, zeta potential, morphology, and drug loading efficiency. Then 35 Wistar male rats were divided into five groups of Sham, SCI, and Oligo-L (10 μL intrathecal injection of 15, 30, and 45 mg/mL). An aneurysm clip was used to induce compression injury of the SCI and Oligo-L groups. Sensory-motor functions were evaluated weekly for 4 weeks using tests such as the BBB scale, inclined plane, acetone drop, hot plate, von Frey, and monitoring of weight changes. Additionally, oxidative stress markers and histological changes were examined to evaluate changes in nitrite, glutathione, catalase, and neuronal survival.

Results and discussion

The findings indicated that Oligo-L treatment led to significant improvements in neuropathic pain, and motor function performance and weight of the animals from the first week post-SCI. Oligo-L also enhanced catalase and glutathione levels while reducing serum nitrite levels, contributing to neuronal preservation. Additionally, Oligo-L increased neuronal survival in the both ventral (motor neurons) and dorsal (sensory neurons) horns of the spinal cord.

Conclusion

Overall, Oligo-L, characterized by its beneficial physicochemical properties, showed promising potential as a neuroprotective agent and facilitated the recovery of sensory and motor functions after SCI.

GABAB receptors regulate the neural stem cell potential of Pkd2l1+ cerebrospinal fluid-contacting neurons via the PI3K/Akt signaling pathway

Cerebrospinal fluid-contacting neurons (CSF-cNs) exhibit neural stem cell (NSC) properties both in vitro and in vivo, and they may play a critical role in recovery after spinal cord injury (SCI). GABAB receptors (GABABRs) are expressed in Pkd2l1+ CSF-cNs. However, their role in Pkd2l1+ CSF-cNs still needs to be discovered. In this study, we observed a significant reduction in GABABR expression in a murine model 7 d after SCI. We further discovered that GABABR activation enhanced the proliferation of Pkd2l1+ CSF-cNs while inhibiting apoptosis. Additionally, this activation mitigated vacuole loss and neuronal damage in the pericentral canal region of the spinal cord, attenuated myelin and axonal loss within the spinal cord, and facilitated motor function recovery in SCI model mice. Mechanistically, GABABR primed quiescent Pkd2l1+ CSF-cNs for cell cycle reentry through the activation of PI3K/Akt signaling. Our findings suggest that GABABR activation enhances the NSC potential of Pkd2l1+ CSF-cNs, ultimately enabling post-SCI recovery in murine models.

Microgel-encapsulated tetrandrine nanoparticles promote spinal cord repair by sustaining neuroinflammation inhibition

Traumatic spinal cord injury (SCI) initiates an intricate secondary injury cascade, characterized by persistent inflammatory responses with neurotoxic microglia and astrocyte activation. Inhibition of neuroinflammation would significantly benefit SCI treatment. Here, tetrandrine with anti-neuroinflammatory activity was delivered into the intrathecal space for SCI treatment. The tetrandrine was encapsulated in MPEG-PDLLA nanoparticles and further loaded into GelMA microgels via a fast 3D printing process based on digital light. After intrathecal injection, the drug-loaded microgels could sustain the release of tetrandrine in the intrathecal space, resulting in efficient repair of the injured spinal cord with recovery of function. Its mechanisms were associated with the modulation of neurotoxic microglia and astrocytes as well as their crosstalk. This work demonstrates a tetrandrine-loaded microgel with potential application in SCI treatment via sustained inhibition of neuroinflammation.

Development of a mouse model of chronic ventral spinal cord compression: Neurobehavioral, radiological, and pathological changes

Objectives

The main objective of this study was to establish a mouse model of spinal ligament ossification to simulate the chronic spinal cord compression observed in patients with ossification of the posterior longitudinal ligament (OPLL). The study also aimed to examine the mice's neurobiological, radiological, and pathological changes.

Methods

In the previous study, a genetically modified mouse strain was created using Crispr-Cas9 technology, namely, Enpp1 flox/flox /EIIa-Cre (C57/B6 background), to establish the OPLL model. Wild-type (WT) mice without compression were used as controls. Functional deficits were evaluated through motor score assessment, inclined plate testing, and gait analysis. The extent of compression was determined using CT imaging. Hematoxylin and eosin staining, luxol fast blue staining, TUNEL assay, immunofluorescence staining, qPCR, and Western blotting were performed to evaluate levels of apoptosis, inflammation, vascularization, and demyelination in the study.

Results

The results demonstrated a gradual deterioration of compression in the Enpp1 flox/flox /EIIa-Cre mice group as they aged. The progression rate was more rapid between 12 and 20 weeks, followed by a gradual stabilization between 20 and 28 weeks. The scores for spinal cord function and strength, assessed using the Basso Mouse Scale and inclined plate test, showed a significant decline. Gait analysis revealed a noticeable reduction in fore and hind stride lengths, stride width, and toe spread. Chronic spinal cord compression resulted in neuronal damage and activated astrocytes and microglia in the gray matter and anterior horn. Progressive posterior cervical compression impeded blood supply, leading to inflammation and Fas-mediated neuronal apoptosis. The activation of Bcl2 and Caspase 3 was associated with the development of progressive neurological deficits (p < 0.05).

Conclusions

The study presents a validated model of chronic spinal cord compression, enabling researchers to explore clinically relevant therapeutic approaches for OPLL.

hBcl2 overexpression in BMSCs enhances resistance to myelin debris-induced apoptosis and facilitates neuroprotection after spinal cord injury in rats

After spinal cord injury (SCI), the accumulation of myelin debris at the lesion exacerbates cell death and hinders axonal regeneration. Transplanted bone marrow mesenchymal stem cells (BMSCs) have been proven to be beneficial for SCI repair, but they are susceptible to apoptosis. It remains unclear whether this apoptotic process is influenced by myelin debris. Here, we constructed rat BMSCs overexpressing human B-cell lymphoma 2 (hBcl2) alone (hBcl2 group), BMSCs overexpressing hBcl2 with an endoplasmic reticulum-anchored segment (hBcl2-cb) (cb group), and a negative control group (NC group) for transplantation in this study. Immunocytochemistry staining validated the successful expression of hBcl2 in BMSCs within the hBcl2 group and cb group. All BMSCs from each group exhibited the ability to phagocytize myelin debris. Nevertheless, only BMSCs derived from the hBcl2 group exhibited heightened resistance to apoptosis and maintained prolonged viability for up to 5 days when exposed to myelin debris. Notably, overexpression of hBcl2 protein, rather than its endoplasmic reticulum-anchored counterpart, significantly enhanced the resistance of BMSCs against myelin debris-induced apoptosis. This process appeared to be associated with the efficient degradation of myelin debris through the Lamp1+ lysosomal pathway in the hBcl2 group. In vivo, the hBcl2 group exhibited significantly higher numbers of surviving cells and fewer apoptotic BMSCs compared to the cb and NC groups following transplantation. Furthermore, the hBcl2 group displayed reduced GFAP+ glial scarring and greater preservation of NF200+ axons in the lesions of SCI rats. Our results suggest that myelin debris triggers apoptosis in transplanted BMSCs, potentially elucidating the low survival rate of these cells after SCI. Consequently, the survival rate of transplanted BMSCs is improved by hBcl2 overexpression, leading to enhanced preservation of axons within the injured spinal cord.

The combination treatment of methylprednisolone and growth factor-rich serum ameliorates the structural and functional changes after spinal cord injury in rat

STUDY DESIGN

Preclinical pharmacology.

OBJECTIVES

Our study aims to evaluate the combined effect of Methylprednisolone (MP) and growth factor-rich serum (GFRS) on structural and functional recovery in rats following spinal cord injury (SCI).

SETTING

Shiraz University of Medical Sciences, Shiraz, Iran METHODS: Male Sprague-Dawley rats were randomly assigned to five groups: sham group (laminectomy); SCI group (the spinal cord clip compression model); SCI-MP group (30 mg/kg MP was administrated intraperitoneally (IP) immediately after SCI); SCI-GFRS group (GFRS (200 µl, IP) was administrated for six consecutive days); and SCI-MP + GFRS group (the rats received MP (30 mg/kg, IP) immediately after SCI, and GFRS (200 µl, IP) for six consecutive days). Motor function was assessed weekly using the Basso, Beattie, and Bresnahan (BBB) scale. After 4 weeks, we conducted the rotarod test, then removed and prepared the spinal cords (including the epicenter of injury) for stereological and histological estimation, and biochemical assays.

RESULTS

The results showed that MP and GFRS combining treatment enhanced functional recovery, which was associated with a decrement in lesion volume, increased spared white and gray matter volume, reduced neuronal loss, as well as decreased necrosis and hemorrhage after SCI. Moreover, administration of MP and GFRS inhibited lipid peroxidation (malondialdehyde (MDA) content), and increased antioxidant enzymes including glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) after rat SCI.

CONCLUSIONS

We suggests that the combination treatment of MP and GFRS may ameliorate the structure and functional changes following SCI by reducing oxidative stress, and increasing the level of antioxidants enzymes.

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.

Astaxanthin ameliorates spinal cord edema and astrocyte activation via suppression of HMGB1/TLR4/NF-κB signaling pathway in a rat model of spinal cord injury

Spinal cord edema is a quick-onset phenomenon with long-term effects. This complication is associated with inflammatory responses, as well as poor motor function. No effective treatment has been developed against spinal edema, which urges the need to provide novel therapies. Astaxanthin (AST) is a fat-soluble carotenoid with anti-inflammatory effects and a promising candidate for treating neurological disorders. This study aimed to investigate the underlying mechanism of AST on the inhibition of spinal cord edema, astrocyte activation, and reduction of inflammatory responsesin a rat compression spinal cord injury (SCI) model. Male rats underwent laminectomy at thoracic 8-9, and the SCI model was induced using an aneurysm clip. After SCI, rats received dimethyl sulfoxide or AST via intrathecal injection. The effects of AST were examined on the motor function, spinal cord edema, integrity of blood-spinal cord barrier (BSCB), and expression of high mobility group box 1 (HMGB1), toll-like receptor 4 (TLR4), nuclear factor-kappa B (NF-κB), glial fibrillary acidic protein (GFAP), and aquaporin-4 (AQP4), and matrix metallopeptidase- 9 (MMP-9) post-SCI. We showed that AST potentially improved the recovery of motor function and inhibited the spinal cord edema via maintaining the integrity of BSCB, reducing the expression of HMGB1, TLR4, and NF-κB, MMP-9 as well as downregulation of astrocyte activation (GFAP) and AQP4 expression. AST improves motor function and reduces edema and inflammatory responses in the spinal tissue. These effects are mediated by suppression of the HMGB1/TLR4/NF-κB signaling pathway, suppressing post-SCI astrocyte activation, and decreasing AQP4 and MMP-9 expression.

A Novel Acute Discogenic Myelopathy Model Using Merocel® Sponge: Comparison With Clip Compression Model in Rats

Objective

Animal models of spinal cord injuries (SCIs) use rats to simulate human SCIs. Among the various techniques, clips have been used to reproduce the compression-contusion model. However, the mechanism of injury in discogenic incomplete SCI may differ from that in clip injury; however, a model has yet to be established. Previously, we issued a patent (No. 10-2053770) for a rat SCI model using Merocel®, a water-absorbing self-expanding polymer sponge. The objectives of this study were to compare the locomotor and histopathological changes between the Merocel®-compression model (MC group) and clip compression model (clip group).

Methods

This study included 4 groups of rats: MC (n=30), MC-sham (n=5), clip (n=30), and clip-sham (n=5). Locomotor function was evaluated in all groups using the Basso, Beattie, and Bresnahan (BBB) scoring system, 4 weeks after injury. Histopathological analyses included morphology, presence of inflammatory cells, microglial activation, and extent of neuronal damage, which were compared among the groups.

Results

The BBB scores in the MC group were significantly higher than those in the clip group throughout the 4 weeks (p<0.01). Neuropathological changes in the MC group were significantly less severe than those in the clip group. In addition, motor neurons were well preserved in the ventral horn of the MC group but poorly preserved in the ventral horn of the clip group.

Conclusion

The novel MC group can help elucidate the pathophysiology of acute discogenic incomplete SCIs and may be applied in various SCI therapeutic strategies.

The Efficiency of Neurospheres Derived from Human Wharton's Jelly Mesenchymal Stem Cells for Spinal Cord Injury Regeneration in Rats

Spinal cord injury (SCI) causes inflammation and neuronal degeneration, resulting in functional movement loss. Since the availability of SCI treatments is still limited, stem cell therapy is an alternative clinical treatment for SCI and neurodegenerative disorders. Human umbilical cord Wharton's jelly-derived mesenchymal stem cells (hWJ-MSCs) are an excellent option for cell therapy. This study aimed to induce hWJ-MSCs into neural stem/progenitor cells in sphere formation (neurospheres) by using neurogenesis-enhancing small molecules (P7C3 and Isx9) and transplant to recover an SCI in a rat model. Inducted neurospheres were characterized by immunocytochemistry (ICC) and gene expression analysis. The best condition group was selected for transplantation. The results showed that the neurospheres induced by 10 µM Isx9 for 7 days produced neural stem/progenitor cell markers such as Nestin and β-tubulin 3 through the Wnt3A signaling pathway regulation markers (β-catenin and NeuroD1 gene expression). The neurospheres from the 7-day Isx9 group were selected to be transplanted into 9-day-old SCI rats. Eight weeks after transplantation, rats transplanted with the neurospheres could move normally, as shown by behavioral tests. MSCs and neurosphere cells were detected in the injured spinal cord tissue and produced neurotransmitter activity. Neurosphere-transplanted rats showed the lowest cavity size of the SCI tissue resulting from the injury recovery mechanism. In conclusion, hWJ-MSCs could differentiate into neurospheres using 10 µM Isx9 media through the Wnt3A signaling pathway. The locomotion and tissue recovery of the SCI rats with neurosphere transplantation were better than those without transplantation.

Synergic Effect of Combined Therapy of Hyperbaric Oxygen and Adipose-Derived Mesenchymal Stem Cells on Improving Locomotor Recovery After Acute Traumatic Spinal Cord Injury in Rat Mainly Through Downregulating Inflammatory and Cell-Stress Signalings

This study tested whether combined hyperbaric oxygen (HBO) and allogenic adipose-derived mesenchymal stem cells (ADMSCs) would be superior to either one for improving the locomotor recovery in rat after acute traumatic spinal cord injury (TSCI) in rat. Adult-male Sprague-Dawley rats were equally categorized into group 1 (sham-operated control), group 2 (TSCI), group 3 (TSCI + HBO for 1.5 h/day for 14 consecutive days after TSCI), group 4 (TSCI + ADMSCs/1.2 × 10⁶ cells by intravenous injection at 3 h and days 1/2 after TSCI), and group 5 (TSCI + HBO + ADMSCs), euthanized, and spinal cord tissue was harvested by day 49 after TSCI. The protein expressions of oxidative-stress (NOX-1/NOX-2), inflammatory-signaling (TLR-4/MyD88/IL-1β/TNF-α/substance-p), cell-stress signaling (PI3K/p-AKT/p-mTOR), and the voltage-gated sodium channel (Nav1.3/1.8/1.9) biomarkers were highest in group 2, lowest in group 1, and significantly lower in group 5 than in groups 3/4 (all <i>P</i> &lt;0.0001), but they did not differ between groups 3 and 4. The spinal cord damaged area, the cellular levels of inflammatory/DNA-damaged biomarkers (CD68+/GFAP+/γ-H2AX+ cells), mitogen-activated protein kinase family biomarkers (p-P38/p-JNK/p-ERK1/2), and cellular expressions of voltage-gated sodium channel (Nav.1.3, Nav.1.8, and Nav.1.9 in NF200+ cells) as well as the pain-facilitated cellular expressions (p-P38+/peripherin+ cells, p-JNK+/peripherin+ cells, p-ERK/NF200+ cells) exhibited an identical pattern of inflammation, whereas the locomotor recovery displayed an opposite pattern of inflammation among the groups (all <i>P</i> &lt; 0.0001). Combined HBO-ADMSCs therapy offered additional benefits for preserving the neurological architecture and facilitated the locomotor recovery against acute TSCI.

Motor Neuroplastic Effects of a Novel Paired Stimulation Technology in an Incomplete Spinal Cord Injury Animal Model

Paired stimulation of the brain and spinal cord can remodel the central nervous tissue circuitry in an animal model to induce motor neuroplasticity. The effects of simultaneous stimulation vary according to the extent and severity of spinal cord injury. Therefore, our study aimed to determine the significant effects on an incomplete SCI rat brain and spinal cord through 3 min and 20 min stimulations after 4 weeks of intervention. Thirty-three Sprague Dawley rats were classified into six groups: (1) normal, (2) sham, (3) iTBS/tsDCS, (4) iTBS/ts-iTBS, (5) rTMS/tsDCS, and (6) rTMS/ts-iTBS. Paired stimulation of the brain cortex and spinal cord thoracic (T10) level was applied simultaneously for 3−20 min. The motor evoked potential (MEP) and Basso, Beattie, and Bresnahan (BBB) scores were recorded after every week of intervention for four weeks along with wheel training for 20 min. Three-minute stimulation with the iTBS/tsDCS intervention induced a significant (p < 0.050 *) increase in MEP after week 2 and week 4 treatments, while 3 min iTBS/ts-iTBS significantly improved MEP (p < 0.050 *) only after the week 3 intervention. The 20 min rTMS/ts-iTBS intervention showed a significant change only in post_5 min after week 4. The BBB score also changed significantly in all groups except for the 20 min rTMS/tsDCS intervention. iTBS/tsDCS and rTMS/ts-iTBS interventions induce neuroplasticity in an incomplete SCI animal model by significantly changing electrophysiological (MEP) and locomotion (BBB) outcomes.

Effects of photobiomodulation in experimental spinal cord injury models: A systematic review

This systematic review investigated the repercussions of photobiomodulation using low-level laser therapy (LLLT) for the treatment of spinal cord injury (SCI) in experimental models. Studies were identified from relevant databases published between January 2009 and December 2021. Nineteen original articles were selected and 68.4% used light at an infrared wavelength. There was a considerable variation of the power used (from 25 to 200 mW), total application time (8-3000 s) and total energy (0.3-450 J). In 79% of the studies, irradiation was initiated immediately after or within 2 h of the SCI, and treatment time ranged continuously from 5 to 21 days. In conclusion, LLLT can be an auxiliary therapy in the treatment of SCI, playing a neuroprotective role, enabling functional recovery, increasing the concentration of nerve connections around the injury site and reducing pro-inflammatory cytokines. However, there is a need for standardization in the dosimetric parameters.

The Effect of ACTH(4–10) PRO8-GLY9-PRO10 Administration on the Expression of IL-6 and IL-8 in Sprague Dawley Mice with Spinal Cord Injury

Background Spinal cord injury (SCI) is a significant cause of morbidity since it results in the inflammation process which leads to necrosis or apoptosis. Inflammatory response to the tissue damage increases IL-6 and IL-8 levels. ACTH4–10Pro8-Gly9-Pro10 is a peptide community that has been shown to have a beneficial effect on minimizing the morbidity and increasing the recovery time.

Methods This study is a true experimental laboratory research with a totally randomized method. The subjects were animal models with light and extreme compression of spinal cord, respectively.

Results The administration of ACTH 4–10 in mild SCI in the 3-hour observation group did not show a significant difference in IL-6 expression compared with the 6-hour observation group. The administration of ACTH 4–10 in severe SCI showed a significantly lower expression level of IL-6 in the 3-hour observation group compared with the 6-hour one. The administration of ACTH 4–10 in severe SCI led to a significantly lower IL-8 expression in the 3-hour observation group compared with the 6-hour one. However, there was no significant difference in IL-8 expression in the group receiving ACTH 4–10 in 3 hours observation compared with that in 6 hours observation.

Conclusion The administration of ACTH4–10Pro8-Gly9-Pro10 can reduce the expression of IL-6 and IL-8 at 3-hour and 6-hour observation after mild and severe SCI in animal models. Future research works are recommended.

The role of MLC901 in reducing VEGF as a vascular permeability marker in rats with spinal cord injury

BACKGROUND

Damaged neural tissue caused by SCI could induce vascular endothelial growth factor (VEGF) that can worsen the condition in the late phase by increasing vascular permeability, thus inducing tissue oedema, which can worsen the infarction. MLC 901 has been widely used in Asia for stroke patients because its mechanism is known to down-regulate VEGF levels in ischemic tissue.

METHODS

Ten Sprague-Dawley rats were used in this experiment. To create a severe spinal cord injury in animal models. The animals were then randomly divided into two groups. MLC 901 was given to the first group, which was the intervention group, and placebo to the second group, which was the control group.

RESULTS

This study showed a decrease in the mean VEGF mRNA expression in the group given MLC 901 compared to the control group, which had a very high mean VEGF mRNA expression starting after 1 h of administration of MLC 901 until day 14 after spinal cord injury. In addition, there was a decrease in VEGF levels in the MLC 901 group compared to the control group from 3 h after spinal cord injury (1 h after MLC 901 administration) to 14 days after spinal cord injury.

CONCLUSION

It can be concluded that administration of MLC 901 can reduce vascular permeability, one of the mechanisms that is thought to occur is to reduce VEGF levels. MLC 901 also maintains the neuroprotective effect provided by VEGF by maintaining this level above the basal level until day 14.

Spinal Cord Injury Inhibits the Differentiation and Maturation of NG2 Cells in the Cerebellum in Mice

OBJECTIVE

Neuroimaging studies have shown that spinal cord injury (SCI) may lead to significant brain changes that are the key factors affecting functional recovery. However, little is known about the molecular and cellular biological mechanisms of these brain changes. The aim of this study was to investigate the molecular and cellular biological changes in the cerebellum after SCI.

METHODS

A total of 72 mice were randomly divided into 2 groups: sham group and SCI group. A mouse model of SCI was established by an aneurysm clip. Pathological examinations of the injured site were performed by hematoxylin and eosin staining and immunohistochemical. Western blot and immunohistochemical were used to determine the effect of SCI on the differentiation and maturation of NG2 cells.

RESULTS

Compared with the sham group, the spinal cord tissue structure was disrupted and the motor function decreased significantly in the SCI group; the number of NG2 cells in the ansiform lobule crus Ⅰ increased on the 7th and 14th days, whereas the expression of oligodendrocyte transcription factor 2, myelin basic protein, and proteolipid protein decreased on the 7th and 14th days after SCI. These results showed that the differentiation and maturation of NG2 cells in the ansiform lobule crus Ⅰ were inhibited after SCI, resulting in the decrease of the formation of mature oligodendrocytes.

CONCLUSIONS

These results indicate that SCI can lead to secondary changes in the cerebellum, which may affect the functional recovery. These findings may be used as biomarkers to evaluate the secondary changes in the brain after SCI.

Analysis and comparison of a spinal cord injury model with a single-axle-lever clip or a parallel-moving clip compression in rats

STUDY DESIGN

Experimental animal study.

OBJECTIVES

To assess the feasibility of a custom-designed parallel-moving (PM) clip, compared with a single-axle-lever (SAL) clip, for the development of a compressional spinal cord injury (SCI) model in rats.

SETTING

Hospital laboratory in China.

METHODS

We used a PM clip and a SAL clip with same compression rate, to develop a SCI model in rats, and set a sham group as a blank control. Within 3 weeks, each group of rats was evaluated for behavioral (Basso-Beattie-Bresnahan locomotor rating score, BBB), and electrophysiological changes (somatosensory evoked potential), and historical staining to observe the differences between the three groups. In particular, the mechanical results of the PM group were calculated.

RESULTS

The BBB scores for the SAL and PM groups were significantly lower than those for the sham group (P < 0.05), no significant difference between the two methods (P > 0.05), but the values corresponding to the PM group had smaller standard deviations. The interpeak-latency (IPL) was significantly prolonged (P < 0.0001) and the peak-peak amplitude (PPA) was significantly reduced (P < 0.01) in SAL and PM groups than those in the sham group, but there was no statistical difference in both IPL and PPA between the two SCI groups (P > 0.05). Histological staining showed obvious pathological changes in two SCI groups, and the shape of the lesion zone in the PM group was more symmetrical than that in the SAL groups.

CONCLUSIONS

The use of a compressional SCI model in rats with the PM clip we designed is an appropriate method to quantify the injury. The degree of the injury caused by this clip is more stable and uniform than those with classical methods.

The Histopathology of Severe Graded Compression in Lower Thoracic Spinal Cord Segment of Rat, Evaluated at Late Post-injury Phase

Spontaneous recovery of lost motor functions is relative fast in rodent models after inducing a very mild/moderate spinal cord injury (SCI), and this may complicate a reliable evaluation of the effectiveness of potential therapy. Therefore, a severe graded (30 g, 40 g and 50 g) weight-compression SCI at the Th9 spinal segment, involving an acute mechanical impact followed by 15 min of persistent compression, was studied in adult female Wistar rats. Functional parameters, such as spontaneous recovery of motor hind limb and bladder emptying function, and the presence of hematuria were evaluated within 28 days of the post-traumatic period. The disruption of the blood-spinal cord barrier, measured by extravasated Evans Blue dye, was examined 24 h after the SCI, when maximum permeability occurs. At the end of the survival period, the degradation of gray and white matter associated with the formation of cystic cavities, and quantitative changes of glial structural proteins, such as GFAP, and integral components of axonal architecture, such as neurofilaments and myelin basic protein, were evaluated in the lesioned area of the spinal cord. Based on these functional and histological parameters, and taking the animal’s welfare into account, the 40 g weight can be considered as an upper limit for severe traumatic injury in this compression model.

Neuromodulatory effects of repetitive transcranial magnetic stimulation on neural plasticity and motor functions in rats with an incomplete spinal cord injury: A preliminary study

We investigated the effects of intermittent theta-burst stimulation (iTBS) on locomotor function, motor plasticity, and axonal regeneration in an animal model of incomplete spinal cord injury (SCI). Aneurysm clips with different compression forces were applied extradurally around the spinal cord at T10. Motor plasticity was evaluated by examining the motor evoked potentials (MEPs). Long-term iTBS treatment was given at the post-SCI 5th week and continued for 2 weeks (5 consecutive days/week). Time-course changes in locomotor function and the axonal regeneration level were measured by the Basso Beattie Bresnahan (BBB) scale, and growth-associated protein (GAP)-43 expression was detected in brain and spinal cord tissues. iTBS-induced potentiation was reduced at post-1-week SCI lesion and had recovered by 4 weeks post-SCI lesion, except in the severe group. Multiple sessions of iTBS treatment enhanced the motor plasticity in all SCI rats. The locomotor function revealed no significant changes between pre- and post-iTBS treatment in SCI rats. The GAP-43 expression level in the spinal cord increased following 2 weeks of iTBS treatment compared to the sham-treatment group. This preclinical model may provide a translational platform to further investigate therapeutic mechanisms of transcranial magnetic stimulation and enhance the possibility of the potential use of TMS with the iTBS scheme for treating SCIs.

Electroacupuncture promotes the recovery of rats with spinal cord injury by suppressing the Notch signaling pathway via the H19/EZH2 axis

Background

Spinal cord injury (SCI) is a life-changing event with an extremely poor prognosis. In our preliminary studies, electroacupuncture (EA) was found to promote the repair of SCI, which was closely related to the Notch signaling pathway. Therefore, in the present study, we hypothesized that EA protects against SCI by inhibiting the Notch signaling pathway and sought to investigate the underlying molecular mechanisms.

Methods

Rat and cell models of SCI were established. The expression of long non-coding RNA H19 was measured by real-time quantitative polymerase chain reaction. The expression levels of EZH2, Notch1, Notch3, Notch4, Hes1, and PS1 protein were measured by western blot. Cell apoptosis and viability were analyzed using flow cytometry and Cell Counting Kit-8 assays, respectively. The expressions of glial fibrillary acidic protein (GFAP) and nestin were detected by immunofluorescence staining.

Results

The expressions of H19, EZH2, and GFAP were significantly increased after SCI but were inhibited by EA; in contrast, nestin expression was significantly decreased by SCI but was restored by EA. Moreover, oxygen-glucose deprivation (OGD) treatment elevated the expression of H19, EZH2, and Notch-related factors as well as apoptosis in PC-12 cells, while suppressing cell viability. Suppressing H19 alleviated the effects of OGD on cell viability and apoptosis, and inhibited the expression of EZH2 and Notch-related factors expression; these effects were reversed by EZH2 overexpression. Finally, EA promoted the recovery of SCI rats and neural stem cell (NSC) proliferation by inhibiting the Notch signaling pathway, which was reversed by H19 overexpression.

Conclusions

Our results demonstrated that EA promotes the recovery of SCI rats and increases the proliferation and differentiation of NSCs by suppressing the Notch signaling pathway via modulating the H19/EZH2 axis.

Platelet-rich plasma in umbilical cord blood reduces neuropathic pain in spinal cord injury by altering the expression of ATP receptors

BACKGROUND

Neuropathic pain following injury or dysfunction of the peripheral or CNS is one of the most important medical challenges to treat. Humane platelet-rich plasma (HPRP), which is a rich source of growth factors, may be able to treat and reduce pain caused by spinal cord injury (SCI). In this study, the effect of HPRP on neuropathic pain caused by SCI was investigated.

METHODS

Sixty adult male Wistar rats were randomly divided into 6 groups: control, sham, SCI, vehicle (SCI+platelet-poor plasma), SCI+ PRP2day (injection 48 hrs after SCI) and SCI+PRP14day (injection 14 days after SCI). SCI was induced at the T12-T13 level. Behavioral tests were conducted weekly after injury for six weeks. Allodynia and hyperalgesia were assessed using acetone drops, plantar test and von Frey filament. Cavity size and the number of fibroblasts were determined by H&E stain, and the expression of mTOR, p-mTOR, P₂×₃R and P₂Y₄R were determined using the western blot technique. Data were analyzed using PRISM & SPSS software.

RESULTS

PRP injection showed a higher pain threshold in mechanical allodynia (p<0.0001), cold allodynia (p<0.0001) and thermal hyperalgesia (p<0.0001) than those in the spinal. Animals treated with PRP also reduced cavity size, fibroblast number, p-mTOR/mTOR ratio, and P₂×₃R expression, and increased P₂Y₄R expression. The difference between the two groups was not statistically significant.

CONCLUSIONS

The results showed that PRP reduced SCI-induced allodynia and hyperalgesia by regulating ATP signaling. Using HPRP can open a new window in the treatment of pain caused by damage to the nervous system.

Animal Models of Cerebral Changes Secondary to Spinal Cord Injury

Spinal cord injuries (SCIs) are difficult to treat. The first animal SCI model (featuring the dropping of a weight) was established by Allen in 1911, and other animal models have been developed since then. Most animal studies have focused only on the molecular features of SCIs, which remain disputed. Recently, it has become clear that SCI may trigger mental and cognitive disorders, however, and brain changes secondary to SCI are under investigation. No consensus on an optimal animal model for cerebral research has emerged. We discuss the appropriate SCI models for studying secondary brain changes.

Modulation of inflammatory factors predicts the outcome following spinal cord injury

BACKGROUND

The correlation between inflammatory responses caused by spinal cord injury (SCI) and the prognosis of patients with SCI still remains controversial.

METHODS

In the present study, we preliminary investigated the serum levels of interleukin (IL)-4, IL-10, major histocompatibility complex (MHC)-I, and inducible nitric oxide synthase (iNOS) and compared the serum IL-4 and IL-10 expression in rats of high Basso-Beattie-Bresnahan (BBB) scores with these of low BBB scores. Besides, the infiltration of macrophage and the axonal regeneration of the injured spinal cord were observed from day 10 to day 30.

RESULTS

We found that higher serum levels of IL-4 and IL-10 can reflect the restorability degree of SCI and could be potential biomarkers for the prognosis of SCI. The infiltration of the M2 subtype of macrophage and the axons regrowth might contribute to a better prognosis.

CONCLUSIONS

The current study demonstrates that the serum levels of IL-4 and IL-10 are preliminarily adopted as serologic markers to forecast SCI, and high serum levels of IL-4 and IL-10 may indicate a better prognosis. Moreover, the way to promote macrophage polarization from M1 to M2 may contribute to better axonal regeneration.

Leuprolide Acetate, a GnRH Agonist, Improves the Neurogenic Bowel in Ovariectomized Rats with Spinal Cord Injury

BACKGROUND

Electromyographic studies have shown that external anal sphincter activity is modified in response to distension in animals with spinal cord injury. Gonadotropin-releasing hormone and its agonist leuprolide acetate have neurotrophic properties in animals with spinal cord injury.

AIM

This study was to determine the effects of leuprolide acetate treatment on electromyographic activity of the external anal sphincter and anorectal manometry in ovariectomized rats with spinal cord injury.

METHODS

Adult ovariectomized rats were divided in three groups: (a) sham of spinal cord injury, (b) spinal cord injury treated with saline solution, and (c) spinal cord injury treated with leuprolide acetate. The spinal cord injury was induced by clamping at level T9. Leuprolide acetate dosage of 10 μg/kg was proctored intramuscular for 5 weeks, commencing the day after the lesion. Electromyography of the external anal sphincter, anorectal manometry, and volume of the cecum were evaluated in all groups.

RESULTS

The electromyographic study of the external anal sphincter activity showed a significant improvement in injured rats treated with leuprolide acetate. Manometric analysis and cecum volume data obtained in animals with leuprolide acetate were very similar to those found in the sham group.

CONCLUSIONS

These results demonstrate that leuprolide acetate treatment improves the neurogenic colon in ovariectomized rats with spinal cord injury.

Tissue-type plasminogen activator-primed human iPSC-derived neural progenitor cells promote motor recovery after severe spinal cord injury

The goal of stem cell therapy for spinal cord injury (SCI) is to restore motor function without exacerbating pain. Induced pluripotent stem cells (iPSC) may be administered by autologous transplantation, avoiding immunologic challenges. Identifying strategies to optimize iPSC-derived neural progenitor cells (hiNPC) for cell transplantation is an important objective. Herein, we report a method that takes advantage of the growth factor-like and anti-inflammatory activities of the fibrinolysis protease, tissue plasminogen activator tPA, without effects on hemostasis. We demonstrate that conditioning hiNPC with enzymatically-inactive tissue-type plasminogen activator (EI-tPA), prior to grafting into a T3 lesion site in a clinically relevant severe SCI model, significantly improves motor outcomes. EI-tPA-primed hiNPC grafted into lesion sites survived, differentiated, acquired markers of motor neuron maturation, and extended βIII-tubulin-positive axons several spinal segments below the lesion. Importantly, only SCI rats that received EI-tPA primed hiNPC demonstrated significantly improved motor function, without exacerbating pain. When hiNPC were treated with EI-tPA in culture, NMDA-R-dependent cell signaling was initiated, expression of genes associated with stemness (Nestin, Sox2) was regulated, and thrombin-induced cell death was prevented. EI-tPA emerges as a novel agent capable of improving the efficacy of stem cell therapy in SCI.

Effects of FABP7 on functional recovery after spinal cord injury in adult mice

OBJECTIVE

Elucidating the mechanisms of neuronal injury is crucial for the development of spinal cord injury (SCI) treatments. Brain-type fatty acid-binding protein 7 (FABP7) is expressed in the adult rodent brain, especially in astrocytes, and has been reported to play a role in astrocyte function in various types of brain damage; however, its role after SCI has not been well studied. In this study, the authors evaluated the expression change of FABP7 after SCI using a mouse spinal cord compression model and observed the effect of FABP7 gene knockout on neuronal damage and functional recovery after SCI.

METHODS

Female FABP7 knockout (KO) mice with a C57BL/6 background and their respective wild-type littermates were subjected to SCI with a vascular clip. The expression of FABP7, neuronal injury, and functional recovery after SCI were analyzed in both groups of mice.

RESULTS

Western blot analysis revealed upregulation of FABP7 in the wild-type mice, which reached its peak 14 days after SCI, with a significant difference in comparison to the control mice. Immunohistochemistry also showed upregulation of FABP7 at the same time points, mainly in proliferative astrocytes. The number of surviving ventral neurons in the FABP7-KO mice at 28 days after SCI was significantly lower than that observed in the wild-type mice. In addition, motor functional recovery in the FABP7-KO mice was significantly worse than that of the wild-type mice.

CONCLUSIONS

The findings of this study indicate that FABP7 could have a neuroprotective role that might be associated with modulation of astrocytes after SCI. FABP7 could potentially be a therapeutic target in the treatment of SCI.

Mesenchymal Stem Cell Transplantation Promotes Functional Recovery through MMP2/STAT3 Related Astrogliosis after Spinal Cord Injury

Background and Objectives

Treatment with mesenchymal stem cells (MSC) in spinal cord injury (SCI) has been highlighted as therapeutic candidate for SCI. Although astrogliosis is a major phenomenon after SCI, the role of astrogliosis is still controversial. In this study, we determined whether acute transplantation of MSC improves the outcome of SCI through modulating astrogliosis.

Methods

Bone marrow derived rat MSCs were induced neural differentiation and transplanted after acute SCI rats. Matrix metalloproteinase (MMP) and neuro-inflammatory pathway were analyzed for acute astrogliosis at 1, 3 and 7 d after SCI in RT-PCR- and western blot analysis. Functional outcome was assessed serially at postoperative 1 d and weekly for 4 weeks. Histopathologic analysis was undertaken at 7 and 28 d following injury in immunohistochemistry.

Results

Transplantation of MSCs decreased IL-1α, CXCL-2, CXCL-10, TNF-α and TGF-β in a rat model of contusive SCI. Protein level of NF-κB p65 was slightly decreased while level of STAT-3 was increased. In immunohistochemistry, MSC transplantation increased acute astrogliosis whereas attenuated scar formation with increased sparing white matter of spinal cord lesions. In RT-PCR analysis, mRNA levels of MMP2 was significantly increased in MSC transplanted rats. In BBB locomotor scale, the rats of MSC treated group exhibited improvement of functional recovery.

Conclusions

Transplantation of MSC reduces the inflammatory reaction and modulates astrogliosis via MMP2/STAT3 pathway leading to improve functional recovery after SCI in rats.

Traumatic Spinal Cord Injury: An Overview of Pathophysiology, Models and Acute Injury Mechanisms

Traumatic spinal cord injury (SCI) is a life changing neurological condition with substantial socioeconomic implications for patients and their care-givers. Recent advances in medical management of SCI has significantly improved diagnosis, stabilization, survival rate and well-being of SCI patients. However, there has been small progress on treatment options for improving the neurological outcomes of SCI patients. This incremental success mainly reflects the complexity of SCI pathophysiology and the diverse biochemical and physiological changes that occur in the injured spinal cord. Therefore, in the past few decades, considerable efforts have been made by SCI researchers to elucidate the pathophysiology of SCI and unravel the underlying cellular and molecular mechanisms of tissue degeneration and repair in the injured spinal cord. To this end, a number of preclinical animal and injury models have been developed to more closely recapitulate the primary and secondary injury processes of SCI. In this review, we will provide a comprehensive overview of the recent advances in our understanding of the pathophysiology of SCI. We will also discuss the neurological outcomes of human SCI and the available experimental model systems that have been employed to identify SCI mechanisms and develop therapeutic strategies for this condition.

Experimental spinal cord injury and behavioral tests in laboratory rats

Traumatic spinal cord injury (SCI) results in some serious neurophysiological consequences that alter healthy body functions and devastate the quality of living of individuals. To find a cure for SCI, researchers around the world are working on different neurorepair and neurorehabilitation modalities. To test a new treatment for SCI as well as to understand the mechanism of recovery, animal models are being widely used. Among them, SCI rat models are arguably the most prominent. Furthermore, it is important to select a suitable behavioral test to evaluate both the motor and sensory recovery following any therapeutic intervention. In this paper, we review the rat models of spinal injury and commonly used behavioral tests to serve as a useful guideline for neuroscientists in the field of SCI research.

Establishing an Organotypic System for Investigating Multimodal Neural Repair Effects of Human Mesenchymal Stromal Stem Cells

Human mesenchymal stromal stem cells (hMSCs) hold regenerative medicine potential due to their availability, in vitro expansion readiness, and autologous feasibility. For neural repair, hMSCs show translational value in research on stroke, spinal cord injury (SCI), and traumatic brain injury. It is pivotal to establish multimodal in vitro systems to investigate molecular mechanisms underlying neural actions of hMSCs. Here, we describe a platform protocol on how to set up organotypic co-cultures of hMSCs (alone or polymer-scaffolded) with explanted adult rat dorsal root ganglia (DRGs) to determine neural injury and recovery events for designing implants to counteract neurotrauma sequelae. We emphasize in vitro hMSC propagation, polymer scaffolding, hMSC stemness maintenance, hMSC-DRG interaction profiling, and analytical formulas of neuroinflammation, trophic factor expression, DRG neurite outgrowth and tropic tracking, and in vivo verification of tailored implants in rodent models of SCI. © 2018 by John Wiley & Sons, Inc.

Epidermal growth factor regulates apoptosis and oxidative stress in a rat model of spinal cord injury

Spinal cord injury (SCI) leads to vascular damage and disruption of blood-spinal cord barrier which participates in secondary nerve injury. Epidermal growth factor (EGF) is an endogenous protein which regulates cell proliferation, growth and differention. Previous studies reported that EGF exerts neuroprotective effect in spinal cord after SCI. However, the molecular mechanisms underlying EGF-mediated protection in different regions of nervous system have not shown yet. In this study, we aimed to examine possible anti-apoptotic and protective roles of EGF not only in spinal cord but also in brain following SCI. Twenty-eight adult rats were divided into four groups of seven animals each as follows: sham, trauma (SCI), SCI + EGF and SCI + methylprednisolone (MP) groups. The functional neurological deficits due to the SCI were assessed by behavioral analysis using the Basso, Beattie and Bresnahan (BBB) open-field locomotor test. The alterations in pro-/anti-apoptotic protein levels and antioxidant enzyme activities were measured in spinal cord and frontal cortex. In our study, EGF promoted locomotor recovery and motor neuron survival of SCI rats. EGF treatment significantly decreased Bax and increased Bcl-2 protein expressions both in spinal cord and brain when compared to SCI group. Moreover, antioxidant enzyme activities including catalase, superoxide dismutase (SOD) and glutathione peroxidase (GPx) were increased following EGF treatment similar to MP treatment. Our experiment also suggests that alteration of the ratio of Bcl-2 to Bax may result from decreased apoptosis following EGF treatment. As a conclusion, these results show, for the first time, that administration of EGF exerts its protection via regulating apoptotic and oxidative pathways in response to spinal cord injury in different regions of central nervous system.

Neuroprotective Effects of C-terminal Domain of Tetanus Toxin on Rat Brain Against Motorneuron Damages After Experimental Spinal Cord Injury

STUDY DESIGN

Experimental animal study investigating the efficacy of C-terminal domain of tetanus toxin application as neuroprotective effects on rat brain in a model of spinal cord injury (SCI).

OBJECTIVE

The aim of the present study was to investigate the possible role of C-terminal domain of tetanus toxin (Hc-TeTx) on cell death mechanisms including apoptosis and autophagy following SCI.

SUMMARY OF BACKGROUND DATA

Traumatic SCI can lead to posttraumatic inflammation, oxidative stress, motor neuron apoptosis, necrosis, and autophagy of tissue. To promote and enhance recovery after SCI, recent development of devices and therapeutic interventions are needed.

METHODS

Twenty-eight adult rats were divided into four groups (n = 7 each) as follows: sham, trauma (SCI), SCI + Hc-TeTx, and SCI + methylprednisolone groups. The functional neurological deficits due to the SCI were assessed by behavioral analysis using the Basso, Beattie and Bresnahan (BBB) open-field locomotor test. The alterations in pro-/anti-apoptotic and autophagy related-protein levels were measured by Western blotting technique.

RESULTS

In this study, Hc-TeTx promotes locomotor recovery and motor neuron survival of SCI rats. Hc-TeTx also decreased expression of bax, bad, bak, cleaved caspase-3, Ask1, and autophagy-related proteins including Atg5 and LC3II in brain. Our study provides an evidence that cell death mechanisms play critical roles in SCI and that the nontoxic peptides including Hc-TeTx may exert protective effect and decrease cell death following SCI.

CONCLUSION

Our preliminary findings suggest a possible therapeutic agent to improve survival after spinal cord trauma, but further analysis are still needed to evaluate the difference between acute and chronic injuries.

LEVEL OF EVIDENCE

N/A.

Transient activation of Wnt/β-catenin signaling reporter in fibrotic scar formation after compression spinal cord injury in adult mice

After traumatic spinal cord injury (SCI), a scar may form with a fibrotic core (fibrotic scar) and surrounding reactive astrocytes (glial scar) at the lesion site. The scar tissue is considered a major obstacle preventing regeneration both as a physical barrier and as a source for secretion of inhibitors of axonal regeneration. Understanding the mechanism of scar formation and how to control it may lead to effective SCI therapies. Using a compression-SCI model on adult transgenic mice, we demonstrate that the canonical Wnt/β-catenin signaling reporter TOPgal (TCF/Lef1-lacZ) positive cells appeared at the lesion site by 5 days, peaked on 7 days, and diminished by 14 days post injury. Using various representative cell lineage markers, we demonstrate that, these transiently TOPgal positive cells are a group of Fibronectin(+);GFAP(-) fibroblast-like cells in the core scar region. Some of them are proliferative. These results indicate that Wnt/β-catenin signaling may play a key role in fibrotic scar formation after traumatic spinal cord injury.

Combined delivery of chondroitinase ABC and human induced pluripotent stem cell-derived neuroepithelial cells promote tissue repair in an animal model of spinal cord injury

The lack of tissue regeneration after traumatic spinal cord injury in animal models is largely attributed to the local inhibitory microenvironment. To overcome this inhibitory environment while promoting tissue regeneration, we investigated the combined delivery of chondroitinase ABC (chABC) with human induced pluripotent stem cell-derived neuroepithelial stem cells (NESCs). ChABC was delivered to the injured spinal cord at the site of injury by affinity release from a crosslinked methylcellulose (MC) hydrogel by injection into the intrathecal space. NESCs were distributed in a hydrogel comprised of hyaluronan and MC and injected into the spinal cord tissue both rostral and caudal to the site of injury. Cell transplantation led to reduced cavity formation, but did not improve motor function. While few surviving cells were found 2 weeks post injury, the majority of live cells were neurons, with only few astrocytes, oligodendrocytes, and progenitor cells. At 9 weeks post injury, there were more progenitor cells and a more even distribution of cell types compared to those at 2 weeks post injury, suggesting preferential survival and differentiation. Interestingly, animals that received cells and chABC had more neurons than animals that received cells alone, suggesting that chABC influenced the injury environment such that neuronal differentiation or survival was favoured.

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.

Experimental spinal cord trauma: a review of mechanically induced spinal cord injury in rat models

It has been shown that animal spinal cord compression (using methods such as clips, balloons, spinal cord strapping, or calibrated forceps) mimics the persistent spinal canal occlusion that is common in human spinal cord injury (SCI). These methods can be used to investigate the effects of compression or to know the optimal timing of decompression (as duration of compression can affect the outcome of pathology) in acute SCI. Compression models involve prolonged cord compression and are distinct from contusion models, which apply only transient force to inflict an acute injury to the spinal cord. While the use of forceps to compress the spinal cord is a common choice due to it being inexpensive, it has not been critically assessed against the other methods to determine whether it is the best method to use. To date, there is no available review specifically focused on the current compression methods of inducing SCI in rats; thus, we performed a systematic and comprehensive publication search to identify studies on experimental spinalization in rat models, and this review discusses the advantages and limitations of each method.

Protective effect of epigenetic silencing of CyclinD1 against spinal cord injury using bone marrow-derived mesenchymal stem cells in rats

This study focuses on the protective effect of epigenetic silencing of CyclinD1 against spinal cord injury (SCI) using bone marrow-derived mesenchymal stem cells (BMSCs) in rats. Eighty-eight adult female Wistar rats were randomly assigned into the sham group, the control group, the si-CyclinD1 + BMSCs group and the BMSCs group. CyclinD1 protein and mRNA expressions after siRNA transfection were detected by Western blotting and qRT-PCR. The siRNA-CyclinD1 BMSCs were transplanted into rats in the si-CyclinD1 + BMSCs group using stereotaxic method 6 hr after SCI. Hindlimb locomotor performance was determined using inclined plane test and Basso-Beattie-Bresnahan (BBB) locomotor rating scale. Expressions of glial fibrillary acidic protein (GFAP) and nerve growth factor (NGF) were detected by immunohistochemistry. Inclined plane and BBB scores in the control, si-CyclinD1 + BMSCs, and BMSCs groups were significantly lower than the sham group, but these scores were evidently decreased in the control group and increased in the si-CyclinD1 + BMSCs group compared with the BMSCs group. The repair degree of spinal cord tissues of rats in the si-CyclinD1 + BMSCs group was obvious than the BMSCs group. GFAP and NGF protein expressions were markedly decreased in the control, si-CyclinD1 + BMSCs and BMSCs groups when compared with the sham group. GFAP- and NGF-positive cells were significantly increased in the si-CyclinD1 + BMSCs group while decreased in the control group. Our study provides evidence that epigenetic silencing of CyclinD1 using BMSCs might accelerate the repair of SCI in rats.

Contusion Spinal Cord Injury Rat Model

Spinal cord injury (SCI) can lead to severe disability, paralysis, neurological deficits and even death. In humans, most spinal cord injuries are caused by transient compression or contusion of the spinal cord associated with motor vehicle accidents. Animal models of contusion mimic the typical SCI's found in humans and these models are key to the discovery of progressive secondary tissue damage, demyelination, and apoptosis as well as pathophysiological mechanisms post SCI. Here we describe a method for the establishment of an efficient and reproducible contusion model of SCI in adult rat.

Chronic administration of [Pyr1] apelin-13 attenuates neuropathic pain after compression spinal cord injury in rats

Apelin is an endogenous ligand for apelin receptor (APJ) with analgesic effect on visceral, analgesic and proanalgesic influences on acute pains in animal models. The purpose of this study was to determine the possible analgesic effects of [Pyr¹] apelin-13 on chronic pain after spinal cord injury (SCI) in rats. Animals were randomly divided into three major groups as intact, sham and SCI. The SCI group randomly allocated to four subgroups as no treatment, vehicle-treatment (normal saline: 10μl, intrathecally) and two subgroups with intrathecal injection (i.t) of 1μg and 5μg of [Pyr¹] apelin-13. After laminectomy at T6-T8 level, spinal cord compression injury was induced using an aneurysm clip. Vehicle or [Pyr¹] apelin-13 injected from day1 post SCI and continued for a week on a daily basis. Pain behaviors and locomotor activity were monitored up to 8weeks. At the end of the experiments, intracardial paraformaldehyde perfusion was made under deep anesthesia in some animals for histological and immunohistochemistry evaluations. Western blot technique was also done to detect caspase-3 in fresh spinal cord tissues. SCI decreased nociceptive thresholds and locomotor scores. Administration of [Pyr¹] apelin-13 (1μg and 5μg) improved locomotor activity and reduced pain symptoms, cavity size and caspase-3 levels. Results showed long-term beneficial effects of [Pyr¹] apelin-13 on neuropathic pain and locomotion. Therefore, we may suggest [Pyr¹] apelin-13 as a new option for further neuropathic pain research and a suitable candidate for ensuing clinical trials in spinal cord injury arena.

Identification of temporal genes involved in the mechanisms of spinal cord injury

OBJECTIVES

As a high-cost neurological disability, spinal cord injury (SCI) can result in permanent paralysis and loss of sensation. To identify the temporal genes involved in the pathogenesis of SCI, we analysed the expression profile of GSE45006.

METHODS

GSE45006 was downloaded from Gene Expression Omnibus, including 20 SCI samples (samples at 1 day, 3 days, 1 week, 2 weeks and 8 weeks after injury, four repetitions for each time point) and 4 normal samples. The Bayesian Estimation of Temporal Regulation (BETR) and randomForest packages were used to screen the temporal genes and the top 100 temporal genes, respectively. Then, the gplots package and Pearson correlation analysis separately were used to perform hot map analysis and expression pattern clustering for the top 100 temporal genes. Using the clusterProfiler package and TargetMine tool, their potential functions were analysed by enrichment analyses. Moreover, interaction relationships between these temporal genes and pathways were investigated by pathway-gene crosslinking networks.

RESULTS

In total, 1907 temporal genes were identified. The top 100 temporal genes were obtained and divided into six clusters. Most of the gene functions were enriched in biological process categories. ARG1 and NOS3 in cluster 4 were enriched in biological process of arginine catabolic process. TGFβ2, TGFβ3, ALDH2 and ALDH3A2 were correlated with numerous pathways in the pathway-gene crosslinking network. Pathways related to TGFβ2 and TGFβ3 were connected to pathways related to ARG1 and NOS3 via ARG1.

CONCLUSION

Several temporal genes, including TGFβ2, TGFβ3, ALDH2, ALDH3A2, ARG1 and NOS3, might be involved in SCI.

Cornel Iridoid Glycoside Improves Locomotor Impairment and Decreases Spinal Cord Damage in Rats

Purpose. This study was to investigate the effects of cornel iridoid glycoside (CIG) on spinal cord injury (SCI) in rats. Methods. The thoracic cord (at T9) of rats was injured by clip compression for 30 sec. Locomotor function was assessed using the Basso, Beattie, and Bresnahan (BBB) rating scale. Neuroanatomic stereological parameters as well as Nogo-A, p75 neurotrophin receptor (p75NTR), and ROCKII expression were measured by histological processing, immunohistochemistry, and stereological analyses. The axons passing through the lesion site were detected by BDA tracing. Results. Intragastric administration of CIG (60 and 180 mg/kg) improved the locomotor impairment at 10, 17, 24, and 31 days post-injury (dpi) compared with untreated SCI model rats. CIG treatment decreased the volume of the lesion epicenter (LEp) and increased the volume of spared tissue and the number of surviving neurons in the injured spinal cord at 31 dpi. CIG promoted the growth of BDA-positive axons and their passage through the lesion site and decreased the expression of Nogo-A, p75NTR, and ROCKII both in and around the LEp. Conclusion. CIG improved the locomotor impairment, decreased tissue damage, and downregulated the myelin-associated inhibition signaling pathway in SCI rats. The results suggest that CIG may be beneficial for SCI therapy.

The immunomodulator decoy receptor 3 improves locomotor functional recovery after spinal cord injury

Background

Spinal cord injury (SCI) causes loss of neurons and axons and results in motor and sensory function impairments. SCI elicits an inflammatory response and induces the infiltration of immune cells, predominantly macrophages, to the injured site. Decoy receptor 3 (DcR3), also known as tumor necrosis factor receptor superfamily member (TNFRSF)-6B, is a pleiotropic immunomodulator capable of inducing macrophage differentiation into the M2 phenotype and enhancing angiogenesis. Because M2 macrophages are crucial for the recovery of impaired motor functions, we ask whether DcR3 is beneficial for the functional recovery of locomotion in Sprague-Dawley (SD) rats after SCI.

Methods

Contusion injury of the spinal cord was performed using a New York University impactor at the ninth thoracic vertebrae, followed by intrathecal injection of 15 μg recombinant protein comprising DcR3 (DcR3.Fc) in 5 μl of normal saline as the treatment, or 5 μl of normal saline as the control, into the injury epicenter. Functional recovery was evaluated using an open-field test weekly up to 6 weeks after injury. The cavity size and myelin sparing in the rostral-to-caudal region, including the epicenter of the injury, were then examined in SCI rats by histological staining. The expression of anti-inflammatory cytokines and the presence of M2 macrophages were determined by quantitative real-time polymerase chain reaction (qPCR) and immunohistochemistry at 7 day after SCI. Statistical analysis was performed using a two-tailed Student’s t test.

Results

Intrathecal administration of DcR3.Fc significantly improved locomotor function and reduced secondary injury with a smaller wound cavity and increased myelin sparing at the lesion site. Compared with the control group, DcR3.Fc-treated rats had increased vascularization at the injury epicenter along with higher levels of interleukin (IL)-4 and IL-10 and lower level of IL-1β on DcR3.Fc-treated rats at day 7 after SCI. Moreover, higher levels of arginase I (Arg I) and CD206 (M2 macrophage markers) and RECA-1 (endothelial marker) were observed in the epicenter on day 7 after SCI by immunofluorescence staining.

Conclusions

These results indicated that DcR3.Fc may promote the M2 macrophage infiltration and enhanced angiogenesis at the lesion site, thus preserving a greater amount of spinal cord tissues and enhancing functional recovery after SCI.

Arachidonic acid pathway alterations in cerebrospinal fluid of dogs with naturally occurring spinal cord injury

Background

Canine intervertebral disc πherniation causes a naturally-occurring spinal cord injury (SCI) that bears critical similarities to human SCI with respect to both injury pathomechanisms and treatment. As such, it has tremendous potential to enhance our understanding of injury biology and the preclinical evaluation of novel therapies. Currently, there is limited understanding of the role of arachidonic acid metabolites in canine SCI.

Results

The CSF concentrations of PLA2 and PGE2 were higher in SCI dogs compared to control dogs (p = 0.0370 and 0.0273, respectively), but CSF LCT4 concentration in SCI dogs was significantly lower than that in control dogs (p < 0.0001). Prostaglandin E2 concentration in the CSF was significantly and positively associated with increased severity of SCI at the time of sampling (p = 0.041) and recovery 42 days post-injury (p = 0.006), as measured by ordinal behavioral scores.

Conclusion

Arachidonic acid metabolism is altered in dogs with SCI, and these data suggest that these AA metabolites reflect injury severity and recovery, paralleling data from other model systems.

Comparative assessment of phototherapy protocols for reduction of oxidative stress in partially transected spinal cord slices undergoing secondary degeneration

BACKGROUND

Red/near-infrared light therapy (R/NIR-LT) has been developed as a treatment for a range of conditions, including injury to the central nervous system (CNS). However, clinical trials have reported variable or sub-optimal outcomes, possibly because there are few optimized treatment protocols for the different target tissues. Moreover, the low absolute, and wavelength dependent, transmission of light by tissues overlying the target site make accurate dosing problematic.

RESULTS

In order to optimize light therapy treatment parameters, we adapted a mouse spinal cord organotypic culture model to the rat, and characterized myelination and oxidative stress following a partial transection injury. The ex vivo model allows a more accurate assessment of the relative effect of different illumination wavelengths (adjusted for equal quantal intensity) on the target tissue. Using this model, we assessed oxidative stress following treatment with four different wavelengths of light: 450 nm (blue); 510 nm (green); 660 nm (red) or 860 nm (infrared) at three different intensities: 1.93 × 10(16) (low); 3.85 × 10(16) (intermediate) and 7.70 × 10(16) (high) photons/cm(2)/s. We demonstrate that the most effective of the tested wavelengths to reduce immunoreactivity of the oxidative stress indicator 3-nitrotyrosine (3NT) was 660 nm. 860 nm also provided beneficial effects at all tested intensities, significantly reducing oxidative stress levels relative to control (p ≤ 0.05).

CONCLUSIONS

Our results indicate that R/NIR-LT is an effective antioxidant therapy, and indicate that effective wavelengths and ranges of intensities of treatment can be adapted for a variety of CNS injuries and conditions, depending upon the transmission properties of the tissue to be treated.