ROS-Responsive Injectable Hydrogel Loaded with SLC7A11-modRNA Inhibits Ferroptosis and Mitigates Intervertebral Disc Degeneration in Rats.

Intervertebral disc degeneration (IVDD) is the primary cause of low back pain, with oxidative stress being a recognized factor that causes its development. Presently, low back pain imposes a significant global economic burden. However, the effectiveness of treatments for IVDD remains extremely limited. Therefore, this study aims to explore innovative and effective IVDD treatments by focusing on oxidative stress as a starting point. In this study, an injectable reactive oxygen species-responsive hydrogel (PVA-tsPBA@SLC7A11 modRNA) is developed, designed to achieve rapid loading and selective release of chemically synthesized modified mRNA (modRNA). SLC7A11 modRNA is specifically used to upregulate the expression of the ferroptosis marker SLC7A11. The local injection of PVA-tsPBA@SLC7A11 modRNA into the degenerated intervertebral disc results in the cleavage of PVA-tsPBA, leading to the release of enclosed SLC7A11 modRNA. The extent of SLC7A11 modRNA release is directly proportional to the severity of IVDD, ultimately ameliorating IVDD by inhibiting ferroptosis in nucleus pulposus cells. This study proposes an innovative system of PVA-tsPBA hydrogel-encapsulated modRNA, representing a potential novel treatment strategy for patients with early-stage IVDD. This article is protected by copyright. All rights reserved.

A Study on Interobserver and Intraobserver Reliability of the Huashan Radiologic Classification System for Cervical Spinal Cord Injury Without Fracture and Dislocation.

STUDY DESIGN: Observational study. OBJECTIVE: To assess the reproducibility and reliability of the system. BACKGROUND: The Huashan radiologic classification system for cervical spinal cord injury without fracture and dislocation (CSCIWFD) was recently proposed and found useful for clinical practice. PATIENTS AND METHODS: Patients diagnosed with CSCIWFD between 2015 and 2021 were recruited. Six spine surgeons from different institutions, three experienced and other inexperienced respectively, were trained as observers of the system, and these surgeons classified the recruited patients using the system. Then, 8 weeks later, they repeated the classification on the same patients in a different order. The interobserver and intraobserver agreement between the results was analyzed using percentage agreement, weighted kappa, and Cohen kappa (κ) statistics. RESULTS: A total of 60 patients were included in the analysis. Type I was the most frequent type (29 cases, 48.3%), followed by type II (13 cases, 21.7%), type III (12 cases, 20%), and type IV (6 cases, 10%). For all the observers, experienced observers, and inexperienced observers, the overall agreement percentages were 77.6% (κ = 0.78), 84.4% (κ = 0.84), and 72.8% (κ = 0.74), respectively, indicating substantial to nearly perfect interobserver reproducibility. A higher level of agreement was found for differentiating type I from other types, with the percentage agreement ranging from 87.8% to 94.4% (κ= 0.74-0.88). For distinguishing compression on the spinal cord (types I and II vs types III and IV) among the different groups of observers, the percentage agreement was 97.8% (κ = 0.94), indicating nearly perfect reproducibility. As for intraobserver agreement, the percentage agreement ranged from 86.7% to 96.7% (κ = 0.78-0.95), indicating at least substantial reliability. CONCLUSIONS: The Huashan radiologic classification system for CSCIWFD was easy to learn and apply in a clinical environment, showing excellent reproducibility and reliability. Therefore, it would be promising to apply and promote this system for the precise evaluation and personalized treatment strategy.

A Novel Cervical Sagittal Classification for Asymptomatic Population Based on Cluster Analysis.

STUDY DESIGN: Cross-sectional study. OBJECTIVE: To propose a novel cervical sagittal classification for asymptomatic people so as to deepen the understanding of cervical sagittal alignment. SUMMARY OF BACKGROUND DATA: Cervical spine sagittal morphology varies in people. There is a lack of widely-accepted cervical sagittal classification method. METHODS: In all, 183 asymptomatic subjects were included. A series of global and segmental cervical sagittal parameters were measured. Subjects with cervical lordosis (CL)<0 degrees were incorporated directly into the kyphosis (K) group. For subjects with CL ≥0 degrees, a two-step cluster analysis was used to arrive at the optimal number of clusters. The results of the expressions for the subtypes were derived by graphing. The 60 randomly selected lateral cervical spine films were evaluated by 4 spine surgeons at 4-week intervals using our classification method, the Toyama classification method and the Donk classification method. The 3 classification methods' reliability was expressed by the intra-group correlation coefficient (ICC), and convenience was expressed by the measuring time. Finally, the distribution of 4 subtypes was depicted, and sagittal parameters were compared among subtypes. RESULTS: Four subtypes of the cervical spine were suggested: Large lordosis (LL): CL≥-1.5×T1 slope (TS)+70°; Small lordosis (SL): -1.5×TS+50°≤CL<-1.5×TS+70°; Straight (S): 0°≤CL<-1.5×TS+50°; and K: CL<0°. The measuring time for our classification method was significantly less than the Toyama classification method (P<0.001). Our classification method showed high inter-observer reliability (ICC=0.856) and high to excellent intra-observer reliability (ICC between 0.851 and 0.913). SL was the most common type (37.7%). Men had more LL type and women had more S type and K type. The proportion of S and K increased with age. Cervical sagittal parameters were significantly different among the subtypes except for C4 vertebral body (VB) angle (P=0.546), C2-C7 SVA (P=0.628) and NT (P=0.816). CONCLUSIONS: We proposed a novel cervical sagittal classification for an asymptomatic population, which proved to be simple to implement with satisfactory reliability.

Evaluation of the modified MRI vertebral bone quality score for bone quality in lumbar degenerative disorders.

OBJECTIVE: The traditional VBQ scoring method may lead to overestimation due to the concentration of intravertebral fat and vascular structures in the posterior half of vertebral bodies, potentially resulting in false-positive outcomes. This study aims to modify the measurement method of VBQ score (Modified-VBQ) and evaluate its effectiveness in evaluating bone quality of lumbar degenerative diseases. METHODS: Retrospective analysis was conducted on clinical data from patients undergoing lumbar surgery for degenerative diseases between September 2022 and September 2023. Preoperative lumbar t1-weighted Magnetic resonance imaging was used for both modified and traditional VBQ scoring. Computed tomography (CT) images and dual-energy X-ray absorptiometry (DEXA) data were collected through the picture archiving and communication system. The effectiveness of the modified VBQ score was evaluated, considering P < 0.05 as statistically significant. RESULTS: The study included 212 patients, revealing a significant difference between the modified VBQ and VBQ scores (P < 0.0001). Notably, patients with a history of hyperlipidemia exhibited a significant difference between the two scores (P = 0.0037). The area under the ROC curve (AUC) for the modified VBQ was 0.86, surpassing the VBQ score (AUC = 0.74). Linear regression analysis demonstrated a moderate to strong correlation between the modified VBQ and DEXA T-score (r = - 0.49, P < 0.0001) and a high correlation with CT Hounsfield units (HU) values (r = - 0.60, P < 0.0001). CONCLUSION: The modified VBQ score provides a simple, effective, and relatively accurate means of assessing bone quality in lumbar degenerative diseases. Preoperative implementation of the modified VBQ score facilitates rapid screening for patients with abnormal bone quality.

Establishment of the Lunar Phase Morphological Classification for Cervical Spinal Canal.

STUDY DESIGN: Retrospective clinical trial. PURPOSE: To establish a morphological classification of the cervical spinal canal using its parameters. OVERVIEW OF LITERATURE: Cervical spine computed tomography (CT) data of 200 healthy volunteers in 2 years were analyzed. The morphology of the spinal cord was also analyzed. METHODS: The median sagittal diameter and transverse diameter of the spinal canal from C2 to C7 were measured on CT images. The ratio of the median sagittal diameter to the transverse diameter was calculated. Accordingly, the spinal canal shape of each segment was classified into four, and the specific criteria of lunar phase classification were determined through linear discriminant analysis based on the ratio of the median sagittal diameter to the transverse diameter. The inter-rater reliability of the classification was explored using Kappa coefficients. Finally, the morphology of the different segments of the cervical spinal canal in healthy volunteers was revised and compared. RESULTS: According to the ratio of the median sagittal diameter and the transverse diameter of the cervical spinal canal, the lunar phase classification of the cervical bony spinal canal was determined as follows: full-moon >0.65, 0.55< convex-moon ≤0.65, 0.46≤ quarter-moon ≤0.55, and residual-moon <0.46. The Kappa values of C2-C7 were 0.851, 0.958, 0.823, 0.927, 0.793, and 0.946, and the Kappa value of all C2-C7 segments was 0.854 that mainly presented two forms of full-moon (76.5%) and convex-moon (23.0%). A quarter-moon spinal canal was mainly distributed in C3, C4, C5, and C6; a residual-moon spinal canal was mainly distributed in C4 and C5; and the morphological distribution of C4 and C5 were similar (p>0.05). The frequency of the spinal canal of the residual-moon type was the highest, and the full-moon (6.5%) and residual-moon (7.5%) types of C7 were rare. CONCLUSIONS: The morphological classification of the cervical spinal canal was established to present anatomical variations. The classification showed good inter-rater reliability.

Altered central pain processing in patients with degenerative lumbar diseases and its association with low physical activity levels after lumbar spinal surgeries: a retrospective cohort analysis.

PURPOSE: To investigate the occurrence of altered central pain modulation in patients with degenerative lumbar diseases (DLDs) and to analyze its association with physical activity (PA) 3 years after lumbar decompression and fusion. METHODS: Preoperative assessments of pressure pain thresholds (PPTs), temporal summation (TS), conditioned pain modulation (CPM) and pain were, respectively, recorded in 304 patients. These patients further underwent International Physical Activity Questionnaire (IPAQ) and both pain-related and psychological assessments 3 years post-operation. RESULTS: Preoperatively, the patients had lower PPTs in both local pain and pain-free areas and lower CPM and higher TS in pain-free areas than healthy subjects (P < 0.05). Postoperatively, 53.9% (164/304) patients showed PA below healthy-related thresholds (< 600 MET min/w). Low PA group showed a greater postoperative weight gain and bone loss and a higher postoperative prevalence of both moderate anxiety and marginal depression than high PA group (P < 0.05). All covariates with differences between the high and low PA groups were subjected to multivariate logistic regression, and long preoperative disease duration, low preoperative PPT in pain-free area, high preoperative TS, revision surgery, severe postoperative low back pain and significant postoperative pain catastrophizing thought were independently associated with low postoperative PA (P < 0.05). CONCLUSIONS: This study supports the existence of central sensitization (CS) caused by abnormal central pain modulation in DLDs. Pre-existing CS in these patients may be associated with low PA after lumbar surgeries, and this low-activity lifestyle may predispose patients to multiple adverse health outcomes. Preoperative dynamic quantitative sensory testing may provide information for the identification of at-risk patients.

C4 constant vertebra: a novel benchmark of physiological cervical sagittal alignment.

BACKGROUND: Cervical sagittal alignment is essential, and there is considerable debate as to what constitutes physiological sagittal alignment. The purpose of this study was to identify constant parameters for characterizing cervical sagittal alignment under physiological conditions. METHODS: A cross-sectional study was conducted in which asymptomatic subjects were recruited to undergo lateral cervical spine radiographs. Each subject was classified according to three authoritative cervical sagittal morphology classifications, followed by the evaluation of variations in radiological parameters across morphotypes. Moreover, the correlations among cervical sagittal parameters, age, and cervicothoracic junction parameters were also investigated. RESULTS: A total of 183 asymptomatic Chinese subjects were enrolled with a mean age of 48.4 years. Subjects with various cervical sagittal morphologies had comparable C4 endplate slope angles under all three different typing systems. Among patients of different ages, C2-C4 endplate slope angles remained constant. Regarding the cervicothoracic junction parameters, T1 slope and thoracic inlet angle affected cervical sagittal parameters, including cervical lordosis and C2-7 sagittal vertical axis, and were correlated with the endplate slope angles of C5 and below and did not affect the endplate slope angles of C4 and above. In general, the slope of the C4 inferior endplate ranges between 13° and 15° under different physiological conditions. CONCLUSIONS: In the asymptomatic population, the C4 vertebral body maintains a constant slope angle under physiological conditions. The novel concept of C4 as a constant vertebra would provide a vital benchmark for diagnosing pathological sagittal alignment abnormalities and planning the surgical reconstruction of cervical lordosis.

The role of leisure-time physical activity in maintaining cervical lordosis after anterior cervical fusion and its impact on the motor function in patients with hirayama disease: a retrospective cohort analysis.

BACKGROUND: Surgical treatment has been increasingly performed in Hirayama disease (HD) patients to limit excessive neck flexion and restore cervical lordosis. However, postoperative recurrence of cervical lordosis loss may restart the progress of HD. Many studies have demonstrated a relationship between neck muscle strength and cervical lordosis, and it is widely accepted that leisure-time physical activity (LTPA) can increase muscle strength. However, there are few reports about the correlation between LTPA and maintenance of postoperative cervical curvature. OBJECTIVE: To quantify the cervical lordosis and motor function before and after operation in HD patients and to analyze the impact of postoperative LTPA levels on the changes in these measurements. METHODS: C2-7 Cobb were measured in 91 HD patients before, 2-5 days and approximately 2 years after operation. Motor unit number estimation (MUNE) and handgrip strength (HGS) were performed in all patients before and approximately 2 years after operation, and both cross-sectional area and fatty infiltration of posterior cervical muscles were measured in 62 patients. Long-form international Physical Activity Questionnaire and its different domains was administered to all patients at postoperative 2-year assessments. RESULTS: The C2-7 Cobb was larger immediately and approximately 2 years after operation than that at preoperative assessment (P < 0.05). The preoperative to postoperative change in C2-7 Cobb was associated with postoperative changes in the symptomatic-side HGS and bilateral MUNE measurements (P < 0.05). Importantly, the patients performing LTPA had greater improvements in C2-7 Cobb from immediate to approximately 2 years after operation and greater C2-7 Cobb at last follow-up than those without LTPA, and postoperative improvements in both symptomatic-side MUNE measurements and symptomatic-side HGS were also greater in the former than in the latter (P < 0.05). CONCLUSIONS: Postoperative LTPA has a positive effect on recovery/maintenance of cervical lordosis after operation, which may alleviate the motor unit loss of distal upper limbs in HD patients. Therefore, postoperative LTPA may be beneficial for postoperative rehabilitation or early conservative treatment of HD patients.

MSC-Derived Exosomes Ameliorate Intervertebral Disc Degeneration By Regulating the Keap1/Nrf2 Axis.

Bone marrow mesenchymal stem cell derived exosomes (BMSC-exos) are a crucial means of intercellular communication and can regulate a range of biological processes by reducing inflammation, decreasing apoptosis and promoting tissue repair. The process of intervertebral disc degeneration (IVDD) is accompanied by increased reactive oxygen species (ROS) because of a decrease in the expression of Nrf2, a critical transcription factor that resists excessive ROS. Our study demonstrated that BMSC-exos decreased ROS production by inhibiting Keap1 and promoting Nrf2 expression, attenuating the apoptosis, inflammation, and degeneration of nucelus pulposus (NP) cells. BMSC-exos promoted an increase in Nrf2 and nuclear translocation, while NF-κB expression was downregulated during this process. Additionally, the expression of antioxidative proteins was elevated after treatment with BMSC-exos. In vivo, we found more NP tissue retention in the BMSC-exos-treated group, along with more expression of Nrf2 and antioxidant-related proteins. Our findings demonstrated for the first time that BMSC-exos could restore the down-regulated antioxidant response system in degenerating NP cells by modulating the Keap1/Nrf2 axis. BMSC-exos could be used as an immediate ROS modulator in the treatment of intervertebral disc degeneration. When BMSC-exos were uptaken by NPCs, the expression of Keap1 decreased and this led to increased expression of Nrf2. Nuclear translocation of Nrf2 then promoted the synthesis of antioxidants against ROS and inhibited NF-kB signalling. Cellular inflammation, apoptosis, and ECM-related indicators were further reduced. Together, the process of IVDD was alleviated.

Changes in Self-Esteem in Patients with Hirayama Disease and its Association with Prognosis After Anterior Cervical Fusion Procedures.

OBJECTIVE: To quantify self-esteem in patients with Hirayama disease (HD) and investigate the impact of this psychosocial factor on surgical outcomes in HD. METHODS: The Rosenberg Self-Esteem Scale (RSES) was measured in 58 patients with HD before anterior cervical fusion. These patients further underwent motor unit number estimation, handgrip strength, disabilities of the arm, shoulder and hand (DASH), Beck Anxiety Inventory (BAI) and Beck Depression Index (BDI) before and 18 months after operation. Furthermore, the International Physical Activity Questionnaire (IPAQ) was administered to all patients at postoperative 18-month assessments. RESULTS: Compared with the general population, patients with HD showed a relatively lower RSES, and RSES was negatively associated with both postoperative DASH (r = -0.431, P < 0.05) and preoperative to postoperative changes (r = -0.295, P < 0.05) and positively associated with IPAQ (r = 0.472, P < 0.05). Similar to the difference in postoperative DASH scores, more patients with low self-esteem felt postoperative aggravated motor dysfunction than those with high/normal self-esteem (P < 0.05). Postoperative BDI exerted a partial mediating effect on the relationship between RSES and DASH scores (B = -0.30, P < 0.05), and postoperative BAI played a partial mediating effect on the relationship between RSES and IPAQ scores (B = 0.30, P < 0.05). CONCLUSIONS: The self-esteem of HD patients may be below the population norms. Importantly, relatively low self-esteem in HD patients may cause/worsen postoperative depression and anxiety, thereby resulting in poor self-reported surgical prognosis and an inactive lifestyle after operation. Therefore, perioperative treatment and rehabilitation efforts in HD patients, especially those with low self-esteem, should account for both physiological and psychological symptoms.

Association of joint hypermobility with range of cervical motion and its impact on the motor unit loss in patients with Hirayama disease.

INTRODUCTION/AIMS: Some patients with Hirayama disease (HD) may have generalized joint hypermobility (GJH), which may excessively increase cervical range of motion (ROM) and then worsen the HD. The purpose of this study was to identify the frequency of GJH in HD patients and to analyze the effect of GJH on cervical ROM and the severity of HD. METHODS: The Beighton scoring system (≥4) was used to diagnose GJH in 84 HD patients. All patients underwent assessments of cervical-flexion/extension ROM; motor unit number estimation in bilateral abductor pollicis brevis (APB) muscles; handgrip strength; and the disabilities of the arm, shoulder, and hand assessments. RESULTS: Concomitant GJH was identified in 20 (23.8%) HD patients. The HD patients with GJH exhibited greater cervical-flexion (P < .001) and cervical-extension (P = .033) ROM than those without GJH. Both greater single motor unit potential amplitudes (symptomatic side: P = .005; less-symptomatic side: P = .011) and lower motor unit numbers (symptomatic side: P = .008; less-symptomatic side: P = .013) in bilateral APB, along with lower compound muscle action potential amplitudes on the symptomatic-side APB (P = .039), were observed in patients with GJH than those without GJH. There was a mild negative correlation between motor unit number and cervical-flexion ROM in HD patients (symptomatic side: r = -0.239, P = .028; less-symptomatic side: r = -0.242, P = .027). DISCUSSION: The frequency of GJH in HD patients may be higher than in the general population. Importantly, GJH may exacerbate excessive cervical-flexion ROM, thereby worsening motor unit loss in HD patients. A cautious approach should be taken when treating HD due to possible comorbid GJH.

N6-methyladenosine hypomethylation of circGPATCH2L regulates DNA damage and apoptosis through TRIM28 in intervertebral disc degeneration.

Circular RNAs (circRNAs) are a class of noncoding RNAs that have been found to be involved in intervertebral disc degeneration (IVDD) progression, and N6-methyladenosine (m6A) broadly exists in circRNAs. Here, we identified circGPATCH2L with a low m6A methylation level to be upregulated in degenerative nucleus pulposus tissues. Mechanistically, as a protein decoy for tripartite motif containing 28 (TRIM28) within aa 402-452 region, circGPATCH2L abrogates the phosphorylation of TRIM28 and inhibits P53 degradation, which contributes to DNA damage accumulation and cellular apoptosis and leads to IVDD progression. Moreover, m6A-methylated circGPATCH2L is recognised and endoribonucleolytically cleaved by a YTHDF2-RPL10-RNase P/MRP complex to maintain the physiological state of nucleus pulposus cells. Thus, our data show the physiological significance of m6A modification in regulating circRNA abundance and provide a potentially effective therapeutic target for the treatment of IVDD.

Correlation Study Between Spinal Cord Function, Spinal Cord Morphology and Cervical Spine Alignments in Patients With Hirayama Disease.

OBJECTIVE: This study aimed to explore the relationship between diffusion tensor imaging (DTI) parameters, cervical spine alignments, and spinal cord morphological parameters in patients with Hirayama disease (HD). METHODS: In this retrospective cohort study, 41 HD patients were recruited from the Huashan hospital from July 2017 to November 2021. Patients received X-rays, conventional magnetic resonance (MR), and DTI scans in flexion and neutral positions. The DTI parameters assessed were calculated using the region of interest (ROI) method. Paired t-tests were performed on the DTI parameters of neck flexion and neutral position. Cervical spine alignments, including flexion and neutral Cobb angles, were measured, and range of motion (ROM) was calculated. Spinal cord morphological parameters were measured, including spinal cord atrophy (SCA) and loss of attachment (LOA). Spearman's correlation analysis between DTI parameters, cervical spine alignments, and spinal cord morphological parameters was performed. RESULTS: In comparing DTI parameters, segments of the C3/4, C4/5, C6/7, and lower cervical spine were significantly different, while segments of C5/6 were not significantly different. In Spearman's correlation analysis, the flexion Cobb angle was significantly correlated with the fractional anisotropy (FA) value (R2 = .111, P = .033) and apparent diffusion coefficient (ADC) value (R2 = .119, P = .027). Flexion FA values were correlated with SCA in C4/5 (R2 = .211, P = .003), C5/6 (R2 = .454, P < .001), and C6/7 (R2 = .383, P < .001) while flexion ADC values were correlated with SCA in the C4/5 (R2 = .178, P = .006), C5/6 (R2 = .388, P < .001) and C6/7 segments (R2 = .187, P = .005). CONCLUSION: The DTI parameters were correlated with the flexion Cobb angle and the SCA. These data support the dynamic cervical flexion compression hypothesis and indicate that the degree of SCA may be used to assess the condition of HD patients quantitatively.

Use of MRI-based vertebral bone quality score (VBQ) of S1 body in bone mineral density assessment for patients with lumbar degenerative diseases.

PURPOSE: To evaluate the use of the modified and simplified vertebral bone quality (VBQ) method based on T1-weighted MRI images of S1 vertebrae in assessing bone mineral density (BMD) for patients with lumbar degenerative diseases. METHODS: We reviewed the preoperative data of patients with lumbar degenerative diseases undergoing lumbar spine surgery between January 2019 and June 2022 with available non-contrast T1-weighted magnetic resonance imaging (MRI), computed tomography (CT) images and dual-energy X-ray absorptiometry (DEXA). S1 vertebral bone quality scores (S1 VBQ) and S1 CT Hounsfield units were measured with picture archiving and communication system (PACS). One-way ANOVA was applied to present the discrepancy between the S1 VBQ of patients with normal bone density (T-score ≥ - 1.0), osteopenia (- 2.5 < T-score < - 1.0) and osteoporosis (T-score ≤ - 2.5). The receiver operating characteristic curve (ROC) was drawn to analyze the diagnostic performance of S1 VBQ in distinguishing low BMD. Statistical significance was set at p < 0.05. RESULTS: A total of 207 patients were included. The S1 VBQ were significantly different between groups (p < 0.001). Interclass correlation coefficient for inter-rater reliability was 0.86 (95% CI 0.78-0.94) and 0.94(95% CI 0.89-0.98) for intra-rater reliability. According to the linear regression analysis, the S1 VBQ has moderate-to-strong correlations with DEXA T-score (r = - 0.48, p < 0.001). The area under the ROC curve indicated a predictive accuracy of 82%. A sensitivity of 77.25% with a specificity of 70% could be achieved for distinguishing low BMD by setting the S1 VBQ cutoff as 2.93. CONCLUSIONS: The S1 VBQ was a promising tool in distinguishing poor bone quality in patients with lumbar degenerative diseases, especially in cases where the previously reported VBQ method based on L1-L4 was not available. S1 VBQ score could be useful as opportunistic assessment for screening and complementary evaluation to DEXA T-score before surgery.

Dihydroorotate dehydrogenase regulates ferroptosis in neurons after spinal cord injury via the P53-ALOX15 signaling pathway.

BACKGROUND: Spinal cord injury (SCI) is a highly disabling condition in spinal surgery that leads to neuronal damage and secondary inflammation. Ferroptosis is a non-apoptotic type of cell death that has only recently been identified, which is marked primarily by iron-dependent and lipid-derived reactive oxygen species accumulation, and accompanied by morphological modifications such as mitochondrial atrophy and increase in membrane density. Dihydroorotate dehydrogenase (DHODH) is a powerful inhibitor of ferroptosis and has been demonstrated to inhibit cellular ferroptosis in tumor cells, but whether it can inhibit neuronal injury following spinal cord injury remains ambiguous. METHODS: In this study, the effect of DHODH on neuronal ferroptosis was observed in vivo and in vitro using a rat spinal cord injury model and erastin-induced PC12 cells, respectively. A combination of molecular and histological approaches was performed to assess ferroptosis and explore the possible mechanisms in vivo and in vitro. RESULTS: First, we confirmed the existence of neuronal ferroptosis after spinal cord injury and that DHODH attenuates neuronal damage after spinal cord injury. Second, we showed molecular evidence that DHODH inhibits the activation of ferroptosis-related molecules and reduces lipid peroxide production and mitochondrial damage, thereby reducing neuronal ferroptosis. Further analysis suggests that P53/ALOX15 may be one of the mechanisms regulated by DHODH. Importantly, we determined that DHODH inhibits ALOX15 expression by inhibiting P53. CONCLUSIONS: Our findings reveal a novel function for DHODH in neuronal ferroptosis after spinal cord injury, suggesting a unique therapeutic target to alleviate the disease process of spinal cord injury.

Engineered exosomes enriched in netrin-1 modRNA promote axonal growth in spinal cord injury by attenuating inflammation and pyroptosis.

BACKGROUND: Spinal cord injury (SCI) brings a heavy burden to individuals and society, and there is no effective treatment at present. Exosomes (EX) are cell secreted vesicles containing molecules such as nucleic acids and proteins, which hold promise for the treatment of SCI. Netrin-1 is an axon guidance factor that regulates neuronal growth. We investigated the effects of engineered EX enriched in netrin-1 chemically synthetic modified message RNA (modRNA) in treating SCI in an attempt to find a novel therapeutic approach for SCI. METHODS: Netrin-1 modRNA was transfected into bone marrow mesenchymal stem cells to obtain EX enriched with netrin-1 (EX-netrin1). We built an inflammatory model in vitro with lipopolysaccharide (LPS) in vitro to study the therapeutic effect of EX-netrin1 on SCI. For experiments in vitro, ELISA, CCK-8 assay, immunofluorescence staining, lactate dehydrogenase release experiments test, real-time quantitative polymerase chain reaction, and western blot were conducted. At the same time, we constructed a rat model of SCI. MRI, hematoxylin-eosin and Nissl staining were used to assess the extent of SCI in rats. RESULTS: In vitro experiments showed that EX had no effect on the viability of oligodendrocytes and PC12 cells. EX-netrin1 could attenuate LPS-induced inflammation and pyroptosis and accelerate axonal/dentritic growth in PC12 cells/oligodendrocytes. In addition, netrin-1 could activate the PI3K/AKT/mTOR signalling pathway upon binding to its receptor unc5b. When Unc5b and PI3K were inhibited, the effect of EX-netrin1 was weakened, which could be reversed by PI3K or mTOR activator. Our in vivo experiments indicated that EX-netrin1 could promote recovery in rats with SCI. CONCLUSION: We found that EX-netrin1 regulated inflammation, pyroptosis and axon growth in SCI via the Unc5b/PI3K/AKT/mTOR pathway, which provides a new strategy for the treatment of SCI.

Sulforaphane Delays Intervertebral Disc Degeneration by Alleviating Endoplasmic Reticulum Stress in Nucleus Pulposus Cells via Activating Nrf-2/HO-1.

Intervertebral disc degeneration (IVDD) is one of the main causes of low back pain, which brings heavy burdens to individuals and society. The mechanism of IVDD is complex and diverse. One of the important reasons is that the abnormal accumulation of reactive oxygen species (ROS) in nucleus pulposus cells (NPCs) leads to endoplasmic reticulum stress (ERS), which causes increased apoptosis of NPCs. Nuclear factor E2-related factor 2 (Nrf-2) and its downstream antioxidant proteins are key molecular switches for sensing oxidative stress and regulating antioxidant responses in cells. Sulforaphane (SFN), a natural compound derived from Brassicaceae plants, is a Nrf-2 agonist that displays potent antioxidant potential in vitro and in vivo. Here, we used advanced glycation end products (AGEs) to construct an in vitro degeneration model of NPCs, and we found that AGEs elevated ROS level in NPCs and caused severe ERS and apoptosis. While SFN can promote the entry of Nrf-2 into the nucleus and increase the expression level of heme oxygenase 1 (HO-1) in vitro, thus clearing the accumulated ROS in cells and alleviating ERS and cell apoptosis. Moreover, the protection of SFN on NPCs was greatly attenuated after HO-1 was inhibited. We also used AGEs to construct a rat IVDD model. Consistent with the in vitro experiments, SFN could attenuate ERS in NPCs in vivo and delay disc degeneration in rats. This study found that SFN can be used as a new and promising agent for the treatment of IVDD.

Loss of cervical sagittal alignment worsens the cervical spinal lesions in patients with Hirayama disease.

OBJECTIVE: To quantify the cervical sagittal alignment in patients with Hirayama disease (HD) and to investigate the effect of loss of cervical sagittal alignment upon the cervical spinal lesions in HD. METHODS: Cervical sagittal alignments were measured in 253 HD patients and 63 healthy subjects by C2-C7 Cobb and a modified method of Toyama et al. Motor unit number estimation (MUNE) was performed in bilateral abductor pollicis brevis (APB) in all HD patients, and 31 patients further underwent cervical diffusion tensor imaging (DTI). RESULTS: Compared with healthy subjects, HD patients showed lower C2-C7 Cobb (P < 0.05), and 83.4% patients showed loss of cervical lordosis (cervical straight or kyphosis), which was greater than healthy subjects (55.6%, P < 0.05). Compared with lordotic/straight group, patients with cervical kyphosis showed lower MUNE values and greater single motor unit potential (SMUP) in bilateral APB, and higher apparent dispersion coefficient (ADC) and lower fractional anisotropy were observed at C4/C5 level in the latter than the former (P < 0.05). C2-C7 Cobb was associated with both C4/C5 ADC and bilateral SMUP (P < 0.05). CONCLUSIONS: Most HD patients showed loss of cervical sagittal alignments, and both MUNE and DTI detections demonstrated a positive correlation between loss of cervical sagittal alignments and cervical spinal lesions in HD. These findings supported that loss of cervical sagittal alignments may worsen motor impairments in HD. Therefore, it is necessary for clinicians to be aware of restoring cervical sagittal alignments during HD treatment.

Efficacy of Anterior Cervical Discectomy and Fusion for Female Patients with Hirayama Disease.

OBJECTIVE: To compare the preoperative and postoperative hand function and radiographic parameters in female patients with Hirayama disease (HD). METHODS: Consecutive female patients with HD undergoing anterior cervical discectomy and fusion were followed up. The postoperative hand functional data were obtained from the last follow-up, whereas the postoperative radiographic data were obtained from the examinations in 3- or 6-month follow-up after surgical treatments. The preoperative and postoperative data of hand functional and radiographic assessments were collected and compared between them. Logistic regression analysis was used to clear potential risk factors for surgical treatment. RESULTS: In all, 15 female patients with HD were included in the follow-up study over 9 years. Significant differences were found in total scores (P < 0.001) and all 6 dimensions, including function (P = 0.003), activities of daily life (P = 0.002), work (P = 0.003), satisfaction (P = 0.002), appearance (P = 0.005), and HD-specific hand symptoms (P = 0.001) in hand functional assessment. The comparison of C2-C7 Cobb angle was statistically different (P = 0.042) in radiographic assessments. The course of illness was of marginal significance (P = 0.065) with curative effect of surgical treatment in logistic regression analysis. CONCLUSIONS: Anterior cervical discectomy and fusion is an effective way to treat female patients with HD, and the course of illness may be correlated with the efficacy of surgery. For some female patients with HD with a clear diagnosis, early surgical treatment is worthy of clinical consideration.