Glycine and N-Acetylcysteine (GlyNAC) Combined with Body Weight Support Treadmill Training Improved Spinal Cord and Skeletal Muscle Structure and Function in Rats with Spinal Cord Injury.

Skeletal muscle atrophy is a frequent complication after spinal cord injury (SCI) and can influence the recovery of motor function and metabolism in affected patients. Delaying skeletal muscle atrophy can promote functional recovery in SCI rats. In the present study, we investigated whether a combination of body weight support treadmill training (BWSTT) and glycine and N-acetylcysteine (GlyNAC) could exert neuroprotective effects, promote motor function recovery, and delay skeletal muscle atrophy in rats with SCI, and we assessed the therapeutic effects of the double intervention from both a structural and functional viewpoint. We found that, after SCI, rats given GlyNAC alone showed an improvement in Basso-Beattie-Bresnahan (BBB) scores, gait symmetry, and results in the open field test, indicative of improved motor function, while GlyNAC combined with BWSTT was more effective than either treatment alone at ameliorating voluntary motor function in injured rats. Meanwhile, the results of the skeletal muscle myofiber cross-sectional area (CSA), hindlimb grip strength, and acetylcholinesterase (AChE) immunostaining analysis demonstrated that GlyNAC improved the structure and function of the skeletal muscle in rats with SCI and delayed the atrophication of skeletal muscle.

The Effect of Glycine and N-Acetylcysteine on Oxidative Stress in the Spinal Cord and Skeletal Muscle After Spinal Cord Injury.

Oxidative stress is a frequently occurring pathophysiological feature of spinal cord injury (SCI) and can result in secondary injury to the spinal cord and skeletal muscle atrophy. Studies have reported that glycine and N-acetylcysteine (GlyNAC) have anti-aging and anti-oxidative stress properties; however, to date, no study has assessed the effect of GlyNAC in the treatment of SCI. In the present work, we established a rat model of SCI and then administered GlyNAC to the animals by gavage at a dose of 200 mg/kg for four consecutive weeks. The BBB scores of the rats were significantly elevated from the first to the eighth week after GlyNAC intervention, suggesting that GlyNAC promoted the recovery of motor function; it also promoted the significant recovery of body weight of the rats. Meanwhile, the 4-week heat pain results also suggested that GlyNAC intervention could promote the recovery of sensory function in rats to some extent. Additionally, after 4 weeks, the levels of glutathione and superoxide dismutase in spinal cord tissues were significantly elevated, whereas that of malondialdehyde was significantly decreased in GlyNAC-treated animals. The gastrocnemius wet weight ratio and total antioxidant capacity were also significantly increased. After 8 weeks, the malondialdehyde level had decreased significantly in spinal cord tissue, while reactive oxygen species accumulation in skeletal muscle had decreased. These findings suggested that GlyNAC can protect spinal cord tissue, delay skeletal muscle atrophy, and promote functional recovery in rats after SCI.

Mechanism of skeletal muscle atrophy after spinal cord injury: A narrative review.

Spinal cord injury leads to loss of innervation of skeletal muscle, decreased motor function, and significantly reduced load on skeletal muscle, resulting in atrophy. Factors such as braking, hormone level fluctuation, inflammation, and oxidative stress damage accelerate skeletal muscle atrophy. The atrophy process can result in skeletal muscle cell apoptosis, protein degradation, fat deposition, and other pathophysiological changes. Skeletal muscle atrophy not only hinders the recovery of motor function but is also closely related to many systemic dysfunctions, affecting the prognosis of patients with spinal cord injury. Extensive research on the mechanism of skeletal muscle atrophy and intervention at the molecular level has shown that inflammation and oxidative stress injury are the main mechanisms of skeletal muscle atrophy after spinal cord injury and that multiple pathways are involved. These may become targets of future clinical intervention. However, most of the experimental studies are still at the basic research stage and still have some limitations in clinical application, and most of the clinical treatments are focused on rehabilitation training, so how to develop more efficient interventions in clinical treatment still needs to be further explored. Therefore, this review focuses mainly on the mechanisms of skeletal muscle atrophy after spinal cord injury and summarizes the cytokines and signaling pathways associated with skeletal muscle atrophy in recent studies, hoping to provide new therapeutic ideas for future clinical work.

In vivo astrocyte-to-neuron reprogramming for central nervous system regeneration: a narrative review.

The inability of damaged neurons to regenerate within the mature central nervous system (CNS) is a significant neuroscientific challenge. Astrocytes are an essential component of the CNS and participate in many physiological processes including blood-brain barrier formation, axon growth regulation, neuronal support, and higher cognitive functions such as memory. Recent reprogramming studies have confirmed that astrocytes in the mature CNS can be transformed into functional neurons. Building on in vitro work, many studies have demonstrated that astrocytes can be transformed into neurons in different disease models to replace damaged or lost cells. However, many findings in this field are controversial, as the source of new neurons has been questioned. This review summarizes progress in reprogramming astrocytes into neurons in vivo in animal models of spinal cord injury, brain injury, Huntington's disease, Parkinson's disease, Alzheimer's disease, and other neurodegenerative conditions.

Sodium selenite promotes neurological function recovery after spinal cord injury by inhibiting ferroptosis.

Ferroptosis is a recently discovered form of iron-dependent cell death, which occurs during the pathological process of various central nervous system diseases or injuries, including secondary spinal cord injury. Selenium has been shown to promote neurological function recovery after cerebral hemorrhage by inhibiting ferroptosis. However, whether selenium can promote neurological function recovery after spinal cord injury as well as the underlying mechanism remain poorly understood. In this study, we injected sodium selenite (3 µL, 2.5 µM) into the injury site of a rat model of T10 vertebral contusion injury 10 minutes after spinal cord injury modeling. We found that sodium selenite treatment greatly decreased iron concentration and levels of the lipid peroxidation products malondialdehyde and 4-hydroxynonenal. Furthermore, sodium selenite increased the protein and mRNA expression of specificity protein 1 and glutathione peroxidase 4, promoted the survival of neurons and oligodendrocytes, inhibited the proliferation of astrocytes, and promoted the recovery of locomotive function of rats with spinal cord injury. These findings suggest that sodium selenite can improve the locomotive function of rats with spinal cord injury possibly through the inhibition of ferroptosis via the specificity protein 1/glutathione peroxidase 4 pathway.

Pathological significance of tRNA-derived small RNAs in neurological disorders.

Non-coding RNAs (ncRNAs) are a type of RNA that is not translated into proteins. Transfer RNAs (tRNAs), a type of ncRNA, are the second most abundant type of RNA in cells. Recent studies have shown that tRNAs can be cleaved into a heterogeneous population of ncRNAs with lengths of 18-40 nucleotides, known as tRNA-derived small RNAs (tsRNAs). There are two main types of tsRNA, based on their length and the number of cleavage sites that they contain: tRNA-derived fragments and tRNA-derived stress-induced RNAs. These RNA species were first considered to be byproducts of tRNA random cleavage. However, mounting evidence has demonstrated their critical functional roles as regulatory factors in the pathophysiological processes of various diseases, including neurological diseases. However, the underlying mechanisms by which tsRNAs affect specific cellular processes are largely unknown. Therefore, this study comprehensively summarizes the following points: (1) The biogenetics of tsRNA, including their discovery, classification, formation, and the roles of key enzymes. (2) The main biological functions of tsRNA, including its miRNA-like roles in gene expression regulation, protein translation regulation, regulation of various cellular activities, immune mediation, and response to stress. (3) The potential mechanisms of pathophysiological changes in neurological diseases that are regulated by tsRNA, including neurodegeneration and neurotrauma. (4) The identification of the functional diversity of tsRNA may provide valuable information regarding the physiological and pathophysiological mechanisms of neurological disorders, thus providing a new reference for the clinical treatment of neurological diseases. Research into tsRNAs in neurological diseases also has the following challenges: potential function and mechanism studies, how to accurately quantify expression, and the exact relationship between tsRNA and miRNA. These challenges require future research efforts.

Dynamic changes in intramedullary pressure 72 hours after spinal cord injury.

Intramedullary pressure increases after spinal cord injury, and this can be an important factor for secondary spinal cord injury. Until now there have been no studies of the dynamic changes of intramedullary pressure after spinal cord injury. In this study, telemetry systems were used to observe changes in intramedullary pressure in the 72 hours following spinal cord injury to explore its pathological mechanisms. Spinal cord injury was induced using an aneurysm clip at T10 of the spinal cord of 30 Japanese white rabbits, while another 32 animals were only subjected to laminectomy. The feasibility of this measurement was assessed. Intramedullary pressure was monitored in anesthetized and conscious animals. The dynamic changes of intramedullary pressure after spinal cord injury were divided into three stages: stage I (steep rise) 1-7 hours, stage II (steady rise) 8-38 hours, and stage III (descending) 39-72 hours. Blood-spinal barrier permeability, edema, hemorrhage, and histological results in the 72 hours following spinal cord injury were evaluated according to intramedullary pressure changes. We found that spinal cord hemorrhage was most severe at 1 hour post-spinal cord injury and then gradually decreased; albumin and aquaporin 4 immunoreactivities first increased and then decreased, peaking at 38 hours. These results confirm that severe bleeding in spinal cord tissue is the main cause of the sharp increase in intramedullary pressure in early spinal cord injury. Spinal cord edema and blood-spinal barrier destruction are important factors influencing intramedullary pressure in stages II and III of spinal cord injury.

Degeneration of white matter and gray matter revealed by diffusion tensor imaging and pathological mechanism after spinal cord injury in canine.

AIM: Exploration of the mechanism of spinal cord degeneration may be the key to treatment of spinal cord injury (SCI). This study aimed to investigate the degeneration of white matter and gray matter and pathological mechanism in canine after SCI. METHODS: Diffusion tensor imaging (DTI) was performed on canine models with normal (n = 5) and injured (n = 7) spinal cords using a 3.0T MRI scanner at precontusion and 3 hours, 24 hours, 6 weeks, and 12 weeks postcontusion. The tissue sections were stained using H&E and immunohistochemistry. RESULTS: For white matter, fractional anisotropy (FA) values significantly decreased in lesion epicenter, caudal segment 1 cm away from epicenter, and caudal segment 2 cm away from epicenter (P = 0.003, P = 0.004, and P = 0.013, respectively) after SCI. Apparent diffusion coefficient (ADC) values were initially decreased and then increased in lesion epicenter and caudal segment 1 cm away from epicenter (P < 0.001 and P = 0.010, respectively). There are no significant changes in FA and ADC values in rostral segments (P > 0.05). For gray matter, ADC values decreased initially and then increased in lesion epicenter (P < 0.001), and overall trend decreased in caudal segment 1 cm away from epicenter (P = 0.039). FA values did not change significantly (P > 0.05). Pathological examination confirmed the dynamic changes of DTI parameters. CONCLUSION: Diffusion tensor imaging is more sensitive to degeneration of white matter than gray matter, and the white matter degeneration may be not symmetrical which meant the caudal degradation appeared to be more severe than the rostral one.

Differential Expression Profiles and Functional Prediction of tRNA-Derived Small RNAs in Rats After Traumatic Spinal Cord Injury.

Spinal cord injury (SCI) is mostly caused by trauma. As the primary mechanical injury is unavoidable, a focus on the underlying molecular mechanisms of the SCI-induced secondary injury is necessary to develop promising treatments for patients with SCI. Transfer RNA-derived small RNA (tsRNA) is a novel class of short, non-coding RNA, possessing potential regulatory functions in various diseases. However, the functional roles of tsRNAs in traumatic SCI have not been determined yet. We used a combination of sequencing, quantitative reverse transcription-polymerase chain reaction (qRT-PCR), bioinformatics, and luciferase reporter assay to screen the expression profiles and identify the functional roles of tsRNAs after SCI. As a result, 297 differentially expressed tsRNAs were identified in rats' spinal cord 1 day after contusion. Of those, 155 tsRNAs were significantly differentially expressed: 91 were significantly up-regulated, whereas 64 were significantly down-regulated after SCI (fold change > 1.5; P < 0.05). Bioinformatics analyses revealed candidate tsRNAs (tiRNA-Gly-GCC-001, tRF-Gly-GCC-012, tRF-Gly-GCC-013, and tRF-Gly-GCC-016) that might play regulatory roles through the mitogen-activated protein kinase (MAPK) and neurotrophin signaling pathways by targeting brain-derived neurotrophic factor (BDNF). We validated the candidate tsRNAs and found opposite trends in the expression levels of the tsRNAs and BDNF after SCI. Finally, tiRNA-Gly-GCC-001 was identified to target BDNF using the luciferase reporter assay. In summary, we found an altered tsRNA expression pattern and predicted tiRNA-Gly-GCC-001 might be involved in the MAPK and neurotrophin pathways by targeting the BDNF, thus regulating the post-SCI pathophysiologic processes. This study provides novel insights for future investigations to explore the mechanisms and therapeutic targets for SCI.

Induced Pluripotent Stem Cell Transplantation Improves Locomotor Recovery in Rat Models of Spinal Cord Injury: a Systematic Review and Meta-Analysis of Randomized Controlled Trials.

BACKGROUND/AIMS: Spinal cord injury (SCI) has long been a subject of great interest in a wide range of scientific fields. Several attempts have been made to demonstrate motor function improvement in rats with SCI after transplantation of induced pluripotent stem cells (iPSC). This systematic review and meta-analysis was designed to summarize the effects of iPSC on locomotor recovery in rat models of SCI. METHODS: We searched the publications in the PubMed, Medline, Science Citation Index, Cochrane Library, CNKI, and Wan-fang databases and the China Biology Medicine disc. Results were analyzed by Review Manager 5.3.0. The quality of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology. RESULTS: Six randomized controlled preclinical trials covering eight comparisons and including 212 rats were selected. The subgroup analyses were based on the following items: different SCI models, cell counts, iPSC sources, iPSC differentiations and transplantation methods. The pooled results indicated that iPSC transplantation significantly improved locomotor recovery of rats after SCI by sustaining beneficial effects, especially in the subgroups of contusion, moderate cell counts (5×105), source of human fetal lung fibroblasts, iPSC-neural precursors and intraspinal injection. CONCLUSION: Our meta-analysis of the effects of iPSC transplantation on locomotor function in SCI models is, to our knowledge, the first meta-analysis in this field. We conclude that iPSC transplantation improves locomotor recovery in rats with SCI, implicating this strategy as an effective therapy. However, more studies are required to validate our conclusions.

Myelotomy promotes locomotor recovery in rats subjected to spinal cord injury: A meta-analysis of six randomized controlled trials.

OBJECTIVE: To investigate the effects of myelotomy on locomotor recovery in rats subjected to spinal cord injury. DATA SOURCES: Electronic databases including PubMed, Science Citation Index, Cochrane Library, China National Knowledge Infrastructure, Chinese Journals Full-text Database, China Biology Medicine disc, and Wanfang Database were searched to retrieve related studies published before September 2017. The MeSH terms (the Medical Subject Headings) such as "myelotomy", "spinal cord injuries", "rats", "randomized controlled trial" and all related entry terms were searched. DATA SELECTION: Randomized controlled trials using myelotomy for the treatment of acute spinal cord injury in rats were included. Basso, Beattie, and Bresnahan scores were adopted as the evaluation method. RevMan Software (version 5.3) was used for data processing. The χ2 and I2 tests were used to assess heterogeneity. Using a random-effects model, a subgroup analysis was conducted to analyze the source of the heterogeneity. OUTCOME MEASURES: Basso, Beattie, and Bresnahan scores were observed 1-6 weeks after spinal cord injury. RESULTS: Six animal trials were included, using a total of 143 lab rats. The included trials were divided into two subgroups by injury degrees (moderate or severe). The pooled results showed that, 1-6 weeks after spinal cord injury, the overall Basso, Beattie, and Bresnahan score was significantly higher in the myelotomy group than in the contusion group (weighted mean difference (WMD) = 0.60; 95% confidence interval (CI): 0.23-0.97; P = 0.001; WMD = 2.10; 95% CI: 1.56-2.64; P < 0.001; WMD = 2.65; 95% CI: 1.73-3.57; P < 0.001; WMD = 1.66; 95% CI: 0.80-2.52; P < 0.001; WMD = 2.09; 95% CI: 0.92-3.26, P < 0.001; WMD = 2.25; 95% CI: 1.06-3.44, P < 0.001). The overall heterogeneity was high (I2 = 85%; I2 = 95%; I2 = 94%; I2 = 88%; I2 = 91%; I2 = 89%). The results in the moderate injury subgroup showed that Basso, Beattie, and Bresnahan scores were significantly higher in the myelotomy group than in the contusion group (WMD = 0.91, 95% CI: 0.52-1.3, P < 0.001; WMD = 2.10; 95% CI: 1.56-2.64, P < 0.001; WMD = 2.65; 95% CI: 1.73-3.57, P < 0.001; WMD = 2.50, 95% CI: 1.72-3.28, P < 0.001; WMD = 3.29, 95% CI: 2.21-4.38, P < 0.001; WMD = 3.27; 95% CI: 2.31-4.23, P < 0.001). The relevant heterogeneity was low. However, there were no significant differences in Basso, Beattie, and Bresnahan scores between the myelotomy and contusion groups in the severe injury subgroup at 2 and 3 weeks after the injury (P = 0.75; P = 0.92). CONCLUSION: : To date, this is the first attempt to summarize the potential effect of myelotomy on locomotor recovery in rats with spinal cord injury. Our findings conclude that myelotomy promotes locomotor recovery in rats with spinal cord injury, especially in those with moderate injury.

Dynamic correlation of diffusion tensor imaging and neurological function scores in beagles with spinal cord injury.

Exploring the relationship between different structure of the spinal cord and functional assessment after spinal cord injury is important. Quantitative diffusion tensor imaging can provide information about the microstructure of nerve tissue and can quantify the pathological damage of spinal cord white matter and gray matter. In this study, a custom-designed spinal cord contusion-impactor was used to damage the T10 spinal cord of beagles. Diffusion tensor imaging was used to observe changes in the whole spinal cord, white matter, and gray matter, and the Texas Spinal Cord Injury Score was used to assess changes in neurological function at 3 hours, 24 hours, 6 weeks, and 12 weeks after injury. With time, fractional anisotropy values after spinal cord injury showed a downward trend, and the apparent diffusion coefficient, mean diffusivity, and radial diffusivity first decreased and then increased. The apparent diffusion-coefficient value was highly associated with the Texas Spinal Cord Injury Score for the whole spinal cord (R = 0.919, P = 0.027), white matter (R = 0.932, P = 0.021), and gray matter (R = 0.882, P = 0.048). Additionally, the other parameters had almost no correlation with the score (P > 0.05). In conclusion, the highest and most significant correlation between diffusion parameters and neurological function was the apparent diffusion-coefficient value for white matter, indicating that it could be used to predict the recovery of neurological function accurately after spinal cord injury.

Circular RNA Expression Alteration and Bioinformatics Analysis in Rats After Traumatic Spinal Cord Injury.

Spinal cord injury (SCI) is mostly caused by trauma. As primary mechanical injury is unavoidable in SCI, a focus on the pathophysiology and underlying molecular mechanisms of SCI-induced secondary injury is necessary to develop promising treatments for SCI patients. Circular RNAs (circRNAs) are associated with various diseases. Nevertheless, studies to date have not yet determined the functional roles of circRNAs in traumatic SCI. We examined circRNA expression profiles in the contused spinal cords of rats using microarray and quantitative reverse transcription-PCR (qRT-PCR) then predict their potential roles in post-SCI pathophysiology with bioinformatics. We found a total of 1676 differentially expressed circRNAs (fold change ≥ 2.0; P < 0.05) in spinal cord 3 days after contusion using circRNA microarray; 1261 circRNAs were significantly downregulated, whereas the remaining 415 were significantly upregulated. Then, five selected circRNAs, namely, rno_circRNA_005342, rno_circRNA_015513, rno_circRNA_002948, rno_circRNA_006096, and rno_circRNA_013017 were all significantly downregulated in the SCI group after verification by qRT-PCR, demonstrating a similar expression pattern in both microarray and PCR data. The next section of the study was concerned with the prediction of circRNA/miRNA/mRNA interactions using bioinformatics analysis. In the final part of the study, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes analyses indicated carbohydrate metabolic process was one of the most significant enrichments and meaningful terms after GO analysis, and the top two signaling pathways affected by the circRNAs-miRNAs axes were the AMP-activated protein kinase signaling pathway and the peroxisome related pathway. In summary, this study showed an altered circRNA expression pattern that may be involved in physiological and pathological processes in rats after traumatic SCI, providing deep insights into numerous possibilities for SCI treatment targets by regulating circRNAs.

[Semicircular decompression for the treatment of old thoracolumbar fractures and intractable neuropathic pain].

OBJECTIVE: To investigate the clinical outcomes of semicircular decompression in treating old thoracolumbar fractures and intractable neuropathic pain. METHODS: From September 2009 to September 2013, 21 patients with old thoracolumbar fracture and intractable neuropathic pain were treated with semicircular decompression. Among initial surgery, posterior pedicle screw fixation was used in these patients, with or without laminectomy. All patients were male, range in age from 20 to 28 years old with an average of (25.00±2.38) years. Vertebral body residual bone block resulted in intra-spinal placeholder more than 50%. All patients were complete spinal cord injury (ASIA grade) or cauda equina injury. VAS scores was from 6 to 10 points with the mean of 7.14±0.91. In these patients, MRI, CT, X-rays were performed; denomination and dosage of analgesics were recorded; nerve function and pain status were respectively evaluated by ASIA grade and VAS score before and after operation. RESULTS: All patients were followed up from 8 to 32 months with an average of (17.29±6.02) months. All bone fragments of spinal canal were removed and spinal cord decompressions were achieved. At final follow-up, VAS scores were from 0 to 8 points with an average of (2.43±2.46) points, and were obviously reduced than peroperative data (P<0.05). Eleven cases of them stopped analgesic intake and 7 cases reduced using. Three patients' symptoms and VAS scores were not improved. CONCLUSION: Old thoracolumbar fractures and intractable neuropathic pain need receive imaging examination as soon as possible and consider semicircular decompression therapy if bone fragments were in vertebral canal and spinal canal stenosis existed. This therapy can effectively relieve pain and profit nerve functional recovery.

Functional restoration of the paralyzed diaphragm in high cervical quadriplegia via phrenic nerve neurotization utilizing the functional spinal accessory nerve.

The authors report a case of functional improvement of the paralyzed diaphragm in high cervical quadriplegia via phrenic nerve neurotization using a functional spinal accessory nerve. Complete spinal cord injury at the C-2 level was diagnosed in a 44-year-old man. Left diaphragm activity was decreased, and the right diaphragm was completely paralyzed. When the level of metabolism or activity (for example, fever, sitting, or speech) slightly increased, dyspnea occurred. The patient underwent neurotization of the right phrenic nerve with the trapezius branch of the right spinal accessory nerve at 11 months postinjury. Four weeks after surgery, training of the synchronous activities of the trapezius muscle and inspiration was conducted. Six months after surgery, motion was observed in the previously paralyzed right diaphragm. The lung function evaluation indicated improvements in vital capacity and tidal volume. This patient was able to sit in a wheelchair and conduct outdoor activities without assisted ventilation 12 months after surgery.