Tail nerve electrical stimulation-induced walking training promotes restoration of locomotion and electrophysiology in rats with chronic spinal cord injury

Functional recovery is the final goal in the treatment of spinal cord injury. However, to date, few treatment strategies have demonstrated significant locomotor improvement in animal experiments. By using tail nerve electrical stimulation (TANES) as an open-field locomotor training method combined with glial scar ablation and cell transplantation, we have successfully promoted locomotor recovery in rats with chronic spinal cord contusion injury. The purpose of the present study is to further investigate the mechanism of TANES and its effect on electrophysiology. Spinal cord segment T10 of female, adult Long-Evans rats was contused using the NYU impactor device with 25 mm height setting. After injury, rats were randomly divided into three groups. Group I was used as a control without any treatment, group II and group III were subjected to basic treatment including glial scar ablation and transplantation of olfactory lamina propria 6 weeks after injury, and group III received TANES-induced open-field locomotor training weekly after basic treatment. All animals were allowed to survive 22 weeks, except some rats which were transected. Basso, Beattie, and Bresnahan (BBB) open-field locomotor rating scale, horizontal ladder rung walking test, and electrophysiological tests were used to assess the restoration of functional behavior and conduction. Results showed that TANES significantly improves locomotor recovery and spinal cord conduction, reflex, as well as significantly reduces the occurrence of autophagia. Additionally, after transection, trained rats still maintained higher BBB score than that of control rats. This may be related to the activity-dependent plasticity promoted by TANES-induced locomotor training.

Eph receptor A4 regulates motor neuron ferroptosis in spinal cord ischemia/reperfusion injury in rats

Previous studies have shown that the receptor tyrosine kinase Eph receptor A4(EphA4) is abundantly expressed in the nervous system. The EphA4 signaling pathway plays an important role in regulating motor neuron ferroptosis in motor neuron disease. To investigate whether EphA4 signaling is involved in ferroptosis in spinal cord ischemia/reperfusion injury, in this study we established a rat model of spinal cord ischemia/reperfusion injury by clamping the left carotid artery and the left subclavian artery. We found that spinal cord ischemia/reperfusion injury increased EphA4 expression in the neurons of anterior horn, markedly worsened ferroptosis-related indicators, substantially increased the number of mitochondria exhibiting features consistent with ferroptosis, promoted deterioration of motor nerve function, increased the permeability of the blood-spinal cord barrier, and increased the rate of motor neuron death. Inhibition of EphA4 largely rescued these effects. However, intrathecal administration of the ferroptosis inducer Erastin counteracted the beneficial effects conferred by treatment with the EphA4 inhibitor. Mass spectrometry and a PubMed search were performed to identify proteins that interact with EphA4, with the most notable being Beclin1 and Erk1/2. Our results showed that inhibition of EphA4 expression reduced binding to Beclin1, markedly reduced p-Beclin1, and reduced Beclin1-XCT complex formation. Inhibition of EphA4 also reduced binding to p-Erk1/2 and markedly decreased the expression of c-Myc, transferrin receptor 1, and p-Erk1/2. Additionally, we observed co-localization of EphA4 and p-Beclin1 and of EphA4 and p-ERK1/2 in neurons in the anterior horn. In conclusion, EphA4 participates in regulating ferroptosis of spinal motor neurons in the anterior horn in spinal cord ischemia/reperfusion injury by promoting formation of the Beclin1-XCT complex and activating the Erk1/2/c-Myc/transferrin receptor 1 axis.

Electrophysiological functional recovery in a rat model of spinal cord hemisection injury following bone marrow-derived mesenchymal stem cell transplantation under hypothermia

Following successful establishment of a rat model of spinal cord hemisection injury by resecting right spinal cord tissues, bone marrow stem cells were transplanted into the spinal cord lesions via the caudal vein while maintaining rectal temperature at 34 ± 0.5°C for 6 hours （mild hypothermia）. Hematoxylin-eosin staining showed that astrocytes gathered around the injury site and formed scars at 4 weeks post-transplantation. Compared with rats transplanted with bone marrow stem cells under normal temperature, rats transplanted with bone marrow stem cells under hypothermia showed increased numbers of proliferating cells （bromodeoxyuridine-positive cells）, better recovery of somatosensory-evoked and motor-evoked potentials, greater Basso, Beattie, and Bresnahan locomotor rating scores, and an increased degree of angle in the incline plate test. These findings suggested that hypothermia combined with bone marrow mesenchymal stem cells transplantation effectively promoted electrical conduction and nerve functional repair in a rat model of spinal cord hemisection injury.

Propofol injection combined with bone marrow mesenchymal stem cell transplantation better improves electrophysiological function in the hindlimb of rats with spinal cord injury than monotherapy

The repair effects of bone marrow mesenchymal stem cell transplantation on nervous system damage are not satisfactory. Propofol has been shown to protect against spinal cord injury. Therefore, this study sought to explore the therapeutic effects of their combination on spinal cord injury. Rat models of spinal cord injury were established using the weight drop method. Rats were subjected to bone marrow mesenchymal stem cell transplantationvia tail vein injection and/or propofol injectionvia tail vein using an infusion pump. Four weeks after cell transplan-tation and/or propofol treatment, the cavity within the spinal cord was reduced. The numbers of PKH-26-positive cells and horseradish peroxidase-positive nerve ifbers apparently increased in the spinal cord. Latencies of somatosensory evoked potentials and motor evoked potentials in the hindlimb were noticeably shortened, amplitude was increased and hindlimb motor function was obviously improved. Moreover, the combined effects were better than cell transplantation or propofol injection alone. The above data suggest that the combination of propofol injection and bone marrow mesenchymal stem cell transplantation can effectively improve hindlimb electro-physiological function, promote the recovery of motor funtion, and play a neuroprotective role in spinal cord injury in rats.

Repetitive magnetic stimulation affects the microenvironment of nerve regeneration and evoked potentials after spinal cord injury

Repetitive magnetic stimulation has been shown to alter local blood flow of the brain, excite the corticospinal tract and muscle, and induce motor function recovery. We established a rat model of acute spinal cord injury using the modified Allen＇s method. After 4 hours of injury, rat models received repetitive magnetic stimulation, with a stimulus intensity of 35% maximum output intensity, 5-Hz frequency, 5 seconds for each sequence, and an interval of 2 minutes. This was repeated for a total of 10 sequences, once a day, 5 days in a week, for 2 consecutive weeks. After repetitive magnetic stimulation, the number of apoptotic cells decreased, matrix metalloproteinase 9/2 gene and protein expression decreased, nestin expression increased, somatosensory and motor-evoked potentials recovered, and motor function recovered in the injured spinal cord. These findings confirm that repetitive magnetic stimulation of the spinal cord improved the microenvironment of neural regeneration, reduced neuronal apoptosis, and induced neuroprotective and repair effects on the injured spinal cord.

Neurological recovery and antioxidant effects of resveratrol in rats with spinal cord injury: a meta-analysis

Objective:To critically assess the neurological recovery and antioxidant effects of resveratrol in rat models of spinal cord injury.Data sources:Using“spinal cord injury”,“resveratrol”and“animal experiment”as the main search terms,all studies on the treatment of spinal cord injury in rats by resveratrol were searched for in PubMed,EMBASE,MEDLINE,Web of Science,Science Direct,China National Knowledge Infrastructure,Wanfang,VIP,and SinoMed databases by computer.The search was conducted from their inception date to April 2017.No language restriction was used in the literature search.Data selection:The methodological quality of each study was assessed by the initial Stroke Therapy Academic Industry Roundtable recommendations.Two reviewers independently selected studies according to the title,abstract and full text.The risk of bias in the included studies was also evaluated.Meta-analyses were performed with Review Manager 5.3 software.Outcome measures:Neurological function was assessed by the Basso,Beattie,and Bresnahan scale score,inclined plane score and Gale’s motor function score.Molecular-biological analysis of antioxidative effects was conducted to determine superoxide dismutase levels,malondialdehyde levels,nitric oxide synthase activity,nitric oxide levels,xanthine oxidase and glutathione levels in spinal cord tissues.Results:The methodological quality of the 12 included studies was poor.The results of meta-analysis showed that compared with the control group,resveratrol significantly increased the Basso,Beattie,and Bresnahan scale scores after spinal cord injury(n=300,mean difference(MD)=3.85,95%confidence interval(CI)[2.10,5.59],P<0.0001).Compared with the control group,superoxide dismutase levels were significantly elevated(n=138,standardized mean difference(SMD)=5.22,95%CI[2.98,7.45],P<0.00001),but malondialdehyde levels were significantly diminished(n=84,SMD=–3.64,95%CI[–5.84,–1.43],P=0.001)in the spinal cord of the resveratrol treatment group.Conclusions:Resveratrol promoted neurological recovery and exerted antioxidative effects in rat models of spinal cord injury.The limited quality of the included studies reduces the application of this meta-analysis.Therefore,more high-quality studies are needed to provide more rigorous and objective evidence for the pre-clinical treatment of spinal cord injury.

Olfactory ensheathing cell transplantation alters the expression of chondroitin sulfate proteoglycans and promotes axonal regeneration after spinal cord injury

Cell transplantation is a potential treatment for spinal cord injury. Olfactory ensheathing cells(OECs) play an active role in the repair of spinal cord injury as a result of the dual characteristics of astrocytes and Schwann cells. However, the specific mechanisms of repair remain poorly understood. In the present study, a rat model of spinal cord injury was established by transection of T10. OECs were injected into the site, 1 mm from the spinal cord stump. To a certain extent, OEC transplantation restored locomotor function in the hindlimbs of rats with spinal cord injury, but had no effect on the formation or volume of glial scars. In addition, OEC transplantation reduced the immunopositivity of chondroitin sulfate proteoglycans(neural/glial antigen 2 and neurocan) and glial fibrillary acidic protein at the injury site, and increased the immunopositivity of growth-associated protein 43 and neurofilament. These findings suggest that OEC transplantation can regulate the expression of chondroitin sulfate proteoglycans in the spinal cord, inhibit scar formation caused by the excessive proliferation of glial cells, and increase the numbers of regenerated nerve fibers, thus promoting axonal regeneration after spinal cord injury. The study was approved by the Animal Ethics Committee of the Medical College of Xi'an Jiaotong University, China(approval No. 2018-2048) on September 9, 2018.

Epidural electrical stimulation effectively restores locomotion function in rats with complete spinal cord injury

Epidural electrical stimulation can restore limb motor function after spinal cord injury by reactivating the surviving neural circuits.In previous epidural electrical stimulation studies,single electrode sites and continuous tetanic stimulation have often been used.With this stimulation,the body is prone to declines in tolerance and locomotion coordination.In the present study,rat models of complete spinal cord injury were established by vertically cutting the spinal cord at the T8 level to eliminate disturbance from residual nerve fibers,and were then subjected to epidural electrical stimulation.The flexible extradural electrode had good anatomical topology and matched the shape of the spinal canal of the implanted segment.Simultaneously,the electrode stimulation site was able to be accurately applied to the L2–3 and S1 segments of the spinal cord.To evaluate the biocompatibility of the implanted epidural electrical stimulation electrodes,GFAP/Iba-1 doublelabeled immunofluorescence staining was performed on the spinal cord below the electrodes at 7 days after the electrode implantation.Immunofluorescence results revealed no significant differences in the numbers or morphologies of microglia and astrocytes in the spinal cord after electrode implantation,and there was no activated Iba-1~+cell aggregation,indicating that the implant did not cause an inflammatory response in the spinal cord.Rat gait analysis showed that,at 3 days after surgery,gait became coordinated in rats with spinal cord injury under burst stimulation.The regained locomotion could clearly distinguish the support phase and the swing phase and dynamically adjust with the frequency of stimulus distribution.To evaluate the matching degree between the flexible epidural electrode(including three stimulation contacts),vertebral morphology,and the level of the epidural site of the stimulation electrode,micro-CT was used to scan the thoracolumbar vertebrae of rats before and after electrode implantation.Based on the experimental results of gait recovery using three-site stimulation electrodes at L2–3 and S1 combined with burst stimulation in a rat model of spinal cord injury,epidural electrical stimulation is a promising protocol that needs to be further explored.This study was approved by the Animal Ethics Committee of Chinese PLA General Hospital(approval No.2019-X15-39)on April 19,2019.

Effects of neural stem cell transplantation on the motor function of rats with contusion spinal cord injuries:a meta-analysis

Objective:To judge the efficacies of neural stem cell(NSC)transplantation on functional recovery following contusion spinal cord injuries(SCIs).Data sources:Studies in which NSCs were transplanted into a clinically relevant,standardized rat model of contusion SCI were identified by searching the PubMed,Embase and Cochrane databases,and the extracted data were analyzed by Stata 14.0.Data selection:Inclusion criteria were that NSCs were used in in vivo animal studies to treat contusion SCIs and that behavioral assessment of locomotor functional recovery was performed using the Basso,Beattie,and Bresnahan lo-comotor rating scale.Exclusion criteria included a follow-up of less than 4 weeks and the lack of control groups.Outcome measures:The restoration of motor function was assessed by the Basso,Beattie,and Bresnahan locomotor rating scale.Results:We identified 1756 non-duplicated papers by searching the aforementioned electronic databases,and 30 full-text articles met the inclusion criteria.A total of 37 studies reported in the 30 articles were included in the meta-analysis.The meta-analysis results showed that transplanted NSCs could improve the motor function recovery of rats following contusion SCIs,to a moderate extent(pooled standardized mean difference(SMD)=0.73;95%confidence interval(CI):0.47–1.00;P<0.001).NSCs obtained from different donor species(rat:SMD=0.74;95%CI:0.36–1.13;human:SMD=0.78;95%CI:0.31–1.25),at different donor ages(fetal:SMD=0.67;95%CI:0.43–0.92;adult:SMD=0.86;95%CI:0.50–1.22)and from different origins(brain-derived:SMD=0.59;95%CI:0.27–0.91;spinal cord-derived:SMD=0.51;95%CI:0.22–0.79)had similar efficacies on improved functional recovery;however,adult induced pluripotent stem cell-derived NSCs showed no significant efficacies.Furthermore,the use of higher doses of transplanted NSCs or the administration of immunosuppressive agents did not promote better locomotor function recovery(SMD=0.45;95%CI:0.21–0.70).However,shorter periods between the contusion induction and the NSC transplantation showed slightly higher efficacies(acute:SMD=1.22;95%CI:0.81–1.63;subacute:SMD=0.75;95%CI:0.42–1.09).For chronic injuries,NSC implantation did not significantly improve functional recovery(SMD=0.25;95%CI:–0.16 to 0.65).Conclusion:NSC transplantation alone appears to be a positive yet limited method for the treatment of contusion SCIs.

Edaravone combined with Schwann cell transplantation may repair spinal cord injury in rats

Edaravone has been shown to delay neuronal apoptosis, thereby improving nerve function and the microenvironment after spinal cord injury. Edaravone can provide a favorable environment for theAa：eatment of spinal cord injury using Schwann cell transplantation. This study used rat models of complete spinal cord transection at T9. Six hours later, Schwann cells were transplanted in the head and tail ends of the injury site. Simultaneously, edaravone was injected through the caudal vein. Eight weeks later, the PKH-26-1abeled Schwann cells had survived and migrated to the center of the spinal cord injury region in rats after combined treatment with edaravone and Schwann cells. Moreover, the number of PKH-26-1abeled Schwann cells in the rat spinal cord was more than that in rats undergoing Schwann cell transplantation alone or rats without any treatment. Horseradish peroxidase retrograde tracing revealed that the number of horserad- ish peroxidase-positive nerve fibers was greater in rats treated with edaravone combined with Schwann cells than in rats with Schwann cell transplantation alone. The results demonstrated that lower extremity motor function and neurophysiological function were better in rats treated with edaravone and Schwann cells than in rats with Schwann cell transplantation only. These data confirmed that Schwann cell transplantation combined with edaravone injection promoted the regeneration of nerve fibers of rats with spinal cord injury and improved neurological function.

The effect of microgene pSVPoMcat to modify Schwann cell on GAP -43 expression after spinal cord injury in adult rats

Objective To study the effect of microgene pSVP oMcat implanted to modify schwann cell on growth associated protein -43(GAP -43)expression after spinal cord injury in adult rats.Method Hemisected of the T8segment of the sp inal cord was performed for all the experiment rats.The rats were randomly divided into three groups as follows:Group Awith microgene pSVPoMca t implanted to genetically modify SC;Group B with SC implanted ;Group C with hemisection of the spinal cord o nly.The changes of expression of GAP-43in spinal cord were observed by immunochemistry with antibodies against GAP -43.Simultaneous,the combined behavioral scores(CBS)was measured.Result There were not any different (P >0.05)among the three groups in first week a nd 12week.There were significant di ffeence(P <0.05)among three groups in 2nd,8th,and more dxpression of GAP -43at the 2nd week in gr oup A.The neurofunctional recovery was best in group A.Conclusion The microgene pSVPoMcat implanted t o modify schwann cell can promote the expression of GAP -43in spinal cord a nd func-tional recovery in adults rats after SCI.

Ninjurin-1: a biomarker for reflecting the process of neuroinflammation after spinal cord injury

Previous studies have shown that Ninjurin-1 participates in cell trafficking and axonal growth following central and peripheral nervous system neuroinflammation.But its precise roles in these processes and involvement in spinal cord injury pathophysiology remain unclear.Western blot assay revealed that Ninjurin-1 levels in rats with spinal cord injury exhibited an upregulation until day 4 post-injury and slightly decreased thereafter compared with sham controls.Immunohistochemistry analysis revealed that Ninjurin-1 immunoreactivity in rats with spinal cord injury sharply increased on days 1 and 4 post-injury and slightly decreased on days 7 and 21 post-injury compared with sham controls.Ninjurin-1 immunostaining was weak in vascular endothelial cells, ependymal cells, and some glial cells in sham controls while it was relatively strong in macrophages, microglia, and reactive astrocytes.These findings suggest that a variety of cells, including vascular endothelial cells, macrophages, and microglia, secrete Ninjurin-1 and they participate in the pathophysiology of compression-induced spinal cord injury.All experimental procedures were approved by the Care and Use of Laboratory Animals of Jeju National University(approval No.2018-0029) on July 6, 2018.

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 Pub Med, 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 Me SH 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. Rev Man Software（version 5.3） was used for data processing. The χ^2 and I^2 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（I^2 = 85%; I^2 = 95%; I^2 = 94%; I^2 = 88%; I^2 = 91%; I^2 = 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.

Glial fibrillary acidic protein levels are associated with global histone H4 acetylation after spinal cord injury in rats

Emerging evidence has suggested global histone H4 acetylation status plays an important role in neural plasticity. For instance, the imbalance of this epigenetic marker has been hypothesized as a key factor for the development and progression of several neurological diseases. Likewise, astrocytic reactivity-a wellknown process that markedly influences the tissue remodeling after a central nervous system injury-is crucial for tissue remodeling after spinal cord injury（SCI）. However, the linkage between the above-mentioned mechanisms after SCI remains poorly understood. We sought to investigate the relation between both glial fibrillary acidic protein（GFAP） and S100 calcium-binding protein B（S100B）（astrocytic reactivity classical markers） and global histone H4 acetylation levels. Sixty-one male Wistar rats（aged ~3 months） were divided into the following groups： sham; 6 hours post-SCI; 24 hours post-SCI; 48 hours post-SCI; 72 hours post-SCI; and 7 days post-SCI. The results suggested that GFAP, but not S100B was associated with global histone H4 acetylation levels. Moreover, global histone H4 acetylation levels exhibited a complex pattern after SCI, encompassing at least three clearly defined phases（first phase： no changes in the 6, 24 and 48 hours post-SCI groups; second phase： increased levels in the 72 hours post-SCI group; and a third phase： return to levels similar to control in the 7 days post-SCI group）. Overall, these findings suggest global H4 acetylation levels exhibit distinct patterns of expression during the first week post-SCI, which may be associated with GFAP levels in the perilesional tissue. Current data encourage studies using H4 acetylation as a possible biomarker for tissue remodeling after spinal cord injury.

Changes in neurological and pathological outcomes in a modified rat spinal cord injury model with closed canal

Most animal spinal cord injury models involve a laminectomy,such as the weight drop model or the transection model.However,in clinical practice,many patients undergo spinal cord injury while maintaining a relatively complete spinal canal.Thus,open spinal cord injury models often do not simulate real injuries,and few previous studies have investigated whether having a closed spinal canal after a primary spinal cord injury may influence secondary processes.Therefore,we aimed to assess the differences in neurological dysfunction and pathological changes between rat spinal cord injury models with closed and open spinal canals.Sprague-Dawley rats were randomly divided into three groups.In the sham group,the tunnel was expanded only,without inserting a screw into the spinal canal.In the spinal cord injury with open canal group,a screw was inserted into the spinal canal to cause spinal cord injury for 5 minutes,and then the screw was pulled out,leaving a hole in the vertebral plate.In the spinal cord injury with closed canal group,after inserting a screw into the spinal canal for 5 minutes,the screw was pulled out by approximately 1.5 mm and the flat end of the screw remained in the hole in the vertebral plate so that the spinal canal remained closed;this group was the modified model,which used a screw both to compress the spinal cord and to seal the spinal canal.At 7 days post-operation,the Basso-Beattie-Bresnahan scale was used to measure changes in neurological outcomes.Hematoxylin-eosin staining was used to assess histopathology.To evaluate the degree of local secondary hypoxia,immunohistochemical staining and western blot assays were applied to detect the expression of hypoxia-inducible factor 1α(HIF-1α)and vascular endothelial growth factor(VEGF).Compared with the spinal cord injury with open canal group,in the closed canal group the Basso-Beattie-Bresnahan scores were lower,cell morphology was more irregular,the percentage of morphologically normal neurons was lower,the percentages of HIF-1α-and VEGF-immunoreactive cells were higher,and HIF-1αand VEGF protein expression was also higher.In conclusion,we successfully established a rat spinal cord injury model with closed canal.This model could result in more serious neurological dysfunction and histopathological changes than in open canal models.All experimental procedures were approved by the Institutional Animal Care Committee of Shanghai Ninth People’s Hospital,Shanghai Jiao Tong University School of Medicine,China(approval No.HKDL201810)on January 30,2018.

Effect of valproic acid on endogenous neural stem cell proliferation in a rat model of spinal cord injury

BACKGROUND： Valproic acid has been reported to decrease apoptosis, promote neuronal differentiation of brain-derived neural stem cells, and inhibit glial differentiation of brain-derived neural stem cells. OBJECTIVE： To investigate the effects of valproic acid on proliferation of endogenous neural stem cells in a rat model of spinal cord injury. DESIGN, TIME AND SETTING： A randomized, controlled, neuropathological study was performed at Key Laboratory of Trauma, Buming, and Combined Injury, Research Institute of Surgery, Daping Hospital, the Third Military Medical University of Chinese PLA between November 2005 and February 2007. MATERIALS： A total of 45 adult, Wistar rats were randomly divided into sham surgery （n = 5）, injury （n = 20）, and valproic acid （n = 20） groups. Valproic acid was provided by Sigma, USA. METHODS： Injury was induced to the T10 segment in the injury and valproic acid groups using the metal weight-dropping method. The spinal cord was exposed without contusion in the sham surgery group. Rats in the valproic acid group were intraperitoneally injected with 150 mg/kg valproic acid every 12 hours （twice in total）.MAIN OUTCOME MEASURES： Nestin expression （5 mm from injured center） was detected using immunohistochemistry at 1,3 days, 1, 4, and 8 weeks post-injury. RESULTS： Low expression of nestin was observed in the cytoplasm, but rarely in the white matter of the spinal cord in the sham surgery group. In the injury group, nestin expression was observed in the ependyma and pia mater one day after injury, and expression reached a peak at 1 week （P 〈 0.05）. Expression was primarily observed in the ependymal cells, which expanded towards the white and gray matter of the spinal cord. Nestin expression rapidly decreased by 4 weeks post-injury, and had almost completely disappeared by 8 weeks. At 24 hours after spinal cord injury, there was no significant difference in nestin expression between the valproic acid and injury groups. At 1 week, there was a significant increase in the number of nestin-positive cells surrounding the central canal in valproic acid group compared with the injury group （P 〈 0.05）. Expression reached a peak by 4 weeks, and it was still present at 8 weeks. CONCLUSION： Valproic acid promoted endogenous neural stem cell proliferation following spinal cord injury in rats.

Effects of Epidural Spinal Cord Stimulation and Treadmill Training on Locomotion Function and Ultrastructure of Spinal Cord Anterior Horn after Moderate Spinal Cord Injury in Rats

Objective:To investigate the effects of epidural spinal cord stimulation(ESCS) and treadmill training on the locomotion function and ultrastructure of spinal cord anterior horn after moderate spinal cord injury in rats.Method:Nine adult female Sprague-Dawley rats were randomly distributed into three groups:①spinal cord injury group(SI,n=3).②spinal cord injury plus ESCS group(SE,n=3).③spinal cord injury plus treadmill training group(TT,n=3).All rats received a moderate spinal cord injury surgery.Four weeks after surgery,rats in SE group received an electrode implantation procedure,with the electrode field covering spinal cord segments L2-S1.Four weeks after electrode implantation,rats received subthreshold ESCS for 30 min/d.Rats in TT group received 4cm/s treadmill training for 30min/d.Rats in SI group received no intervention,as a control group.All procedures in these three groups lasted four weeks.The open field Basso,Beattie and Bresnahan(BBB) scale was used before and after intervention to evaluate rats' hindlimb motor function.Result:After four weeks intervention,rats in TT group improved their open field locomotion scores to 20.In contrast,no significant improvement was observed in groups SI and SE.The morphology of synapses and neurons were similar regardless of whether rats had undergone ESCS,treadmill training or not.Conclusion:ESCS alone was not sufficient to improve the walking ability of spinal cord injured rats.ESCS or treadmill training alone might not contribute to the changes of ultrastructure in anterior horn of spinal cord that underlie the recovery of walking ability.Further research is needed to understand the contributions of combination of ESCS and treadmill training to the rehabilitation of spinal cord injured rats.

Effect of electro-acupuncture on the expression of heat shock protein-70 gene in rat spinal cords following spinal cord injury

BACKGROUND： It is generally believed that the mechanism by which heat shock protein-70 （HSP70） protects cells is related to its effectiveness in maintaining the normal stereochemical structure of intracellular proteins, and in participating in the process of cell apoptosis. Whether electro-acupuncture participates in HSP70 expression and produces neuroprotective effects remain unclear. OBJECTIVE： This study aimed at detecting HSP70 expression after electro-acupuncture in rats with transected spinal cord, in order to further validate the mechanism of electro-acupuncture-induced effects in the treatment of spinal cord injury. DESIGN： A controlled observational experiment. SETTING： Shanghai University of Traditional Chinese Medicine and Toho University, School of Medicine. MATERIALS： Seventy adult male Sprague-Dawley rats of SPF grade, weighing 200± 20 g, were provided by the Laboratory Animal Center of Shanghai University of Traditional Chinese Medicine, with permission No. SYXK （hu） 2004 - 2005. The animals were handled in accordance with the requests from Animal Ethics Committees for guidance. A G6805-2 multiple purpose treatment machine was used （Shanghai Medical Instruments High-Tech Co.,Ltd., Shanghai, China）. METHODS： This study was carried out in the state level laboratories of Shanghai University of Traditional Chinese Medicine and Toho University, School of Medicine between January 2005 and July 2007. The rats were randomly divided into the electro-acupuncture treated group, which received electro-acupuncture treatment in addition to spinal cord surgery and the control group, which received only spinal cord surgery, with 35 rats in each group. All the rats underwent the same surgery consisting of spinal cord transection at the T10 level. If the spinal cord was completely transected and the two posterior limbs were completely paralyzed, then the surgery was considered successful and the animal was kept for further analysis and testing. After surgery, rats in the experimental group were electro-acupunctured with a G6805-2 multiple purpose treatment machine. Two needle electrodes were inserted under the T7 and T10 spinal processes, The treatment was administered once a day for 20 minutes. Rats in the control group were not given any treatment after surgery. Five rats were sacrificed separately in each group on days 1, 2, 3, 7, 14, 21 and 28 after surgery. HSP70 gene expression at the site of lesion was located and quantitatively analyzed by immunohistochemistry and real-time PCR methods. Simultaneously, the spinal cord injury region and neurons were observed by HE and Klüver-Barrera stainings. MAIN OUTCOME MEASURES： （1）HSP70 gene expression in the spinal cord injury region. （2） The number of neurons in the spinal cord injury region. RESULTS： Seventy rats were involved in the final analysis. （1）At the end of each pre-determined block of time, HSP70 mRNA level in the spinal cord injury region of rats in the electro-acupuncture treated group was significantly higher than that in the control group （P 〈 0.05）. HSP70 gene expression in the two groups reached peak levels on day 2 after surgery. （2） On days 7, 14, 21 and 28 after surgery, the number of neurons in the spinal cord injury region in the electro-acupuncture treated group was significantly higher than that in the control group （P 〈 0.05）. CONCLUSION： Electro-acupuncture can effectively enhance HSP70 expression in the spinal cord injury region. HSP70 may participate in this apparent neuroprotective effect.

APOPTOSIS AFTER SPINAL CORD INJURY IN RATS

Objective To confirm the role played by apoptosis in spinal cord injury. Methods 36 rats models of spinal cord injury were made by Allen method. Histological examinations using HE staining and in situ end-labeling were used to observe apoptosis in spinal cord tissues from 1h to 21d after injury. Results HE staining sections showed hemorrhage and necrosis, neuronal degeneration and glial cell proliferation. In situ end-labeling sections showed the appearance of apoptosis in both gray and white matter as well as in both central and surrounding region. The number of apoptotic cells increased from l2h after injury, increased to the peak at 4d and declined to normal at 21d. Conclusion The results suggest that apoptosis, especially glial apoptosis, plays a role in the pathogenesis of spinal cord injury.

A comprehensive study of long-term skeletal changes after spinal cord injury in adult rats

Spinal cord injury（SCI）-induced bone loss represents the most severe osteoporosis with no effective treatment.Past animal studies have focused primarily on long bones at the acute stage using adolescent rodents. To mimic chronic SCI in human patients, we performed a comprehensive analysis of long-term structural and mechanical changes in axial and appendicular bones in adult rats after SCI. In this experiment, 4-month-old Fischer 344 male rats received a clinically relevant T13 contusion injury. Sixteen weeks later, sublesional femurs, tibiae,and L4 vertebrae, supralesional humeri, and blood were collected from these rats and additional non-surgery rats for micro-computed tomography（m CT）, micro-finite element, histology, and serum biochemical analyses.At trabecular sites, extreme losses of bone structure and mechanical competence were detected in the metaphysis of sublesional long bones after SCI, while the subchondral part of the same bones showed much milder damage. Marked reductions in bone mass and strength were also observed in sublesional L4 vertebrae but not in supralesional humeri. At cortical sites, SCI induced structural and strength damage in both sub- and supralesional long bones. These changes were accompanied by diminished osteoblast number and activity and increased osteoclast number and activity. Taken together, our study revealed site-specific effects of SCI on bone and demonstrated sustained inhibition of bone formation and elevation of bone resorption at the chronic stage of SCI.