Ferroptosis contributes to intervertebral disc degeneration (IVDD), yet its upstream regulatory mechanisms in nucleus pulposus cells (NPCs) remain unclear. Here, we identify a novel UCHL3-HMGB1-NCOA4 signaling axis that drives NPC ferroptosis. Transcriptomic and clinical analyses reveal that UCHL3 is upregulated in degenerative discs, with its expression correlating positively with both IVDD severity and ferroptosis markers. Mechanistically, UCHL3 deubiquitinates and stabilizes HMGB1 by cleaving Lys48-linked polyubiquitin chains, thereby promoting the accumulation of cytoplasmic HMGB1. This stabilized HMGB1 activates NCOA4-mediated ferritinophagy, initiating ferroptosis. Silencing UCHL3 or NCOA4 mitigates these effects. Furthermore, a polydopamine-based nanoplatform (PDA@si-UCHL3) achieves dual therapeutic action, silencing UCHL3 while scavenging ROS and chelating iron, which effectively inhibits ferroptosis and alleviates IVDD in rats. These findings establish UCHL3 as a pivotal regulator of NPC ferroptosis and highlight PDA@si-UCHL3 as a promising therapeutic strategy for IVDD.Abbreviations: AAV: adeno-associated virus; CCK-8: cell counting kit-8; Co-IP: co-immunoprecipitation; DUBs: deubiquitinating enzymes; ECM: extracellular matrix; GPX4: glutathione peroxidase 4; GSH: glutathione; HE: hematoxylin and eosin; HMGB1: high mobility group box 1; IF: immunofluorescence; IHC: immunohistochemistry; IP/MS: immunoprecipitation mass spectrometry; IVDD: intervertebral disc degeneration; IVDs: intervertebral discs; MRI: magnetic resonance imaging; NCOA4: nuclear receptor coactivator 4; NP: nucleus pulposus; NPCs: nucleus pulposus cells; PDA: polydopamine; PG: Pfirrmann grading; ROS: reactive oxygen species; siRNA: small interfering RNAs; SO-FG: Safranin O-Fast Green; TBHP: tert-butyl hydroperoxide; TEM: transmission electron microscope; UCHL3: ubiquitin C-terminal hydrolase L3; WT: wild-type.

Background:Spinal cord injury (SCI) is a severe central nervous system disorder for which effective therapeutic interventions remain limited. Accumulating evidence indicates that ferroptosis is a key contributor to secondary neuronal damage following SCI, yet its upstream regulators-particularly those involving post-translational modifications such as ubiquitination-remain incompletely understood. This study aimed to determine whether the E3 ubiquitin ligase TRIM59 modulates neuronal ferroptosis and functional recovery after SCI, and to elucidate its molecular substrate and underlying mechanism of action. Methods:TRIM59 expression was modulated using lentiviral vectors in cultured neurons and adeno-associated virus serotype 9 (AAV9) in mice. Functional recovery was assessed through the BMS, inclined plane test, footprint analysis, and motor evoked potentials. Ferroptosis was evaluated via biochemical assays, BODIPY C11 staining, ROS detection, TEM, and ferroptosis markers. Molecular interactions were analyzed by co-immunoprecipitation (Co-IP), ubiquitination assays, and cycloheximide (CHX) chase experiment. Results:TRIM59 expression was significantly downregulated during Erastin-induced ferroptosis in neurons and in spinal cord tissue during the acute phase (days 1-3) after SCI. Downregulation of TRIM59 exacerbated the hallmark features of ferroptosis and impaired motor recovery, whereas TRIM59 overexpression attenuated ferroptosis and promoted neurological restoration. Mechanistically, TRIM59 directly bound to ANXA2 and mediated its K48-linked polyubiquitination and subsequent proteasomal degradation. The neuroprotective effect of TRIM59 was abolished by a catalytically inactive C30A mutant or by ANXA2 overexpression, whereas ANXA2 knockdown rescued the ferroptosis and functional deficits induced by TRIM59 deficiency. Conclusion:This study identifies a novel TRIM59-ANXA2 regulatory axis that critically governs neuronal ferroptosis and functional recovery after SCI. TRIM59 functions as an endogenous suppressor of ferroptosis by targeting ANXA2 for K48-linked ubiquitin-proteasome-mediated degradation. These findings not only elucidate a key post-translational mechanism in SCI pathophysiology but also position TRIM59 as a promising therapeutic target for neuroprotection and functional restoration following SCI. The translational potential of this article:Targeting the TRIM59-ANXA2 pathway offers a promising therapeutic strategy to inhibit ferroptosis and promote neuroprotection and functional recovery after SCI. Enhancing TRIM59 activity or disrupting ANXA2 stability could pave the way for novel treatments in clinical neurotrauma.

Spinal cord injury (SCI) is a debilitating disorder characterized by intricate pathological processes that result in severe motor and sensory deficits. Existing therapeutic approaches remain insufficient to achieve comprehensive functional restoration, indicating the necessity of alternative treatment strategies. In this study, an advanced nanoparticle-based drug delivery system was established using extracellular vesicles (EVs) modified with a matrix metalloproteinase (MMP)-responsive peptide, ACPP, to achieve the targeted delivery of paclitaxel (PTX). The ACPP-EVs@PTX formulation integrates the drug loading capacity of EVs, the lesion-targeting capability conferred by ACPP, and the neuroprotective properties of PTX. Enhanced accumulation of PTX at the SCI lesion site was achieved, accompanied by a reduction in the off-target distribution. Both in vitro and in vivo experiments demonstrated marked therapeutic efficacy of ACPP-EVs@PTX through modulation of the SCI microenvironment, including stimulation of angiogenesis, attenuation of inflammatory responses, alleviation of oxidative stress, and promotion of axonal regeneration. In addition, the activation of PINK1-Parkin-mediated mitophagy was observed, leading to improved mitochondrial function and enhanced neuronal repair. Behavioral evaluations further confirmed significant recovery of neurological function, supporting the translational potential of this multitarget, synergistic therapeutic strategy. Collectively, this work establishes an integrated therapeutic strategy for spinal cord repair and supports its translational potential.

Spinal cord injury (SCI) is a severe central nervous system disorder. It often results in permanent sensory and motor deficits, with no effective therapeutic strategies available. Oxidative stress and ferroptosis are significant contributors to secondary neuronal damage following SCI. This study investigated the therapeutic potential and molecular mechanisms of apoptotic extracellular vesicles (ApoEVs) derived from human umbilical cord mesenchymal stem cells (UC-MSCs) in SCI repair. Our findings reveal that UC-MSC-ApoEVs significantly improve motor function, promote neuronal survival, and preserve tissue integrity in a murine SCI model. These results demonstrate their robust neuroprotective effects. Mechanistically, ApoEVs regulate ferroptosis-related molecules, including GPX4, TFR1, and ACSL4, reducing iron accumulation and lipid peroxidation. Additionally, ApoEVs maintain mitochondrial function, thereby inhibiting neuronal ferroptosis. Furthermore, proteomic analysis and functional validation identified OTUD1, a deubiquitinating enzyme enriched in ApoEVs, as a key regulator interacting directly with NRF2. OTUD1 stabilizes NRF2 via deubiquitination, enhancing its antioxidant response. Silencing OTUD1 in ApoEVs significantly diminished their anti-ferroptotic and neuroprotective effects, highlighting the pivotal role of OTUD1 in mediating therapeutic benefits. This study uncovers a novel OTUD1-NRF2 regulatory axis in ferroptosis inhibition, providing new insights into the development of ApoEV-based acellular therapies for SCI.

Spinal cord injury (SCI) causes high morbidity, disability, and mortality, while current surgical and pharmacological treatments provide limited benefit. Ferroptosis, a newly recognized form of regulated cell death, contributes critically to SCI pathology, and targeting this process may enhance neuronal survival. Extracellular vesicles, key mediators of intercellular communication, are emerging as promising therapeutic agents for central nervous system injury. Here, we examined the role of athlete-derived plasma extracellular vesicles (AEVs) in neuronal ferroptosis and motor function recovery after SCI. In a murine model, AEVs markedly inhibited ferroptosis and improved motor outcomes. Mechanistically, AEVs delivered RNF216, which promoted ubiquitination and degradation of NOX1, thereby reducing ferroptotic damage and facilitating recovery. Moreover, RNF216-enriched vesicles enhanced synaptic plasticity, supporting neuronal regeneration and network reestablishment. These findings reveal a previously unrecognized RNF216-NOX1 axis in SCI and highlight AEVs as a previously unidentified therapeutic strategy.

Bone metastasis (BM) is a major contributor to poor prognosis of prostate cancer (PCa); however, the underlying mechanisms of PCa BM remain poorly understood. A better understanding of these processes may provide critical insights for developing effective preventive and therapeutic strategies for PCa BM. In this study, significant upregulation of CCDC183-AS1 in PCa BM is identified, which is associated with disease progression. CCDC183-AS1 overexpression enhanced the ability of PCa cells to spread to the bone by inducing osteoclastogenesis and aiding in the creation of a BM niche. Mechanistically, CCDC183-AS1 interacted with FUBP1 and enhanced its stability by inhibiting JTV-1-mediated ubiquitination and degradation of FUBP1, which promoted the transcription of TNFSF14 (LIGHT). Copy number gain-induced upregulation of KDM5C epigenetically enhanced CCDC183-AS1 expression by recruiting TET1 to its promoter and promoting DNA demethylation. Significantly, the administration of the selective FUBP1 inhibitor, FUBP1-IN-1, is shown to effectively suppress CCDC183-AS1-induced PCa BM. These results shed light on the involvement of CCDC183-AS1 in enhancing osteoclastogenesis and the underlying mechanism in facilitating PCa BM, offering a potential avenue for therapeutic interventions.

Selenophosphate synthetase 1 (SEPHS1) deficiency leads to an increase in reactive oxygen species levels and in the subsequent activation of the Hippo-Yap/Taz signaling pathway. In the rat model of intervertebral disc degeneration (IVDD), overexpression of SEPHS1 and inhibition of Hippo-YAP/Taz mitigated the progression of disc degeneration indicating the involvement of SEPHS1 in IVDD. SEPHS1 is a promising therapeutic target for IVDD.

Improving the function of the blood-spinal cord barrier (BSCB) benefits the functional recovery of mice following spinal cord injury (SCI). The death of endothelial cells and disruption of the BSCB at the injury site contribute to secondary damage, and the ubiquitin-proteasome system is involved in regulating protein function. However, little is known about the regulation of deubiquitinated enzymes in endothelial cells and their effect on BSCB function after SCI. We observed that Sox17 is predominantly localized in endothelial cells and is significantly upregulated after SCI and in LPS-treated brain microvascular endothelial cells. In vitro Sox17 knockdown attenuated endothelial cell proliferation, migration, and tube formation, while in vivo Sox17 knockdown inhibited endothelial regeneration and barrier recovery, leading to poor functional recovery after SCI. Conversely, in vivo overexpression of Sox17 promoted angiogenesis and functional recovery after injury. Additionally, immunoprecipitation-mass spectrometry revealed the interaction between the deubiquitinase UCHL1 and Sox17, which stabilized Sox17 and influenced angiogenesis and BSCB repair following injury. By generating UCHL1 conditional knockout mice and conducting rescue experiments, we further validated that the deubiquitinase UCHL1 promotes angiogenesis and restoration of BSCB function after injury by stabilizing Sox17. Collectively, our findings present a novel therapeutic target for treating SCI by revealing a potential mechanism for endothelial cell regeneration and BSCB repair after SCI.

Spinal cord injury (SCI) is a severe neurological condition that frequently leads to significant sensory, motor, and autonomic dysfunction. This study sought to delineate the potential mechanistic underpinnings of extracellular vesicles (EVs) derived from ginsenoside Rg1-pretreated neuronal cells (Rg1-EVs) in ameliorating SCI. These results demonstrated that treatment with Rg1-EVs substantially improved motor function in spinal cord-injured mice. Rg1-EVs enhance microglial polarization toward the M2 phenotype and repressed oxidative stress, thereby altering immune responses and decreasing inflammatory cytokine secretion. Moreover, Rg1-EVs substantially diminish reactive oxygen species accumulation and enhanced neural tissue repair by regulating mitochondrial function. Proteomic profiling highlighted a significant enrichment of MYCBP2 in Rg1-EVs, and functional assays confirmed that MYCBP2 knockdown counteracted the beneficial effects of Rg1-EVs in vitro and in vivo. Mechanistically, MYCBP2 is implicated in the ubiquitination and degradation of S100A9, thereby promoting microglial M2-phenotype polarization and reducing oxidative stress. Overall, these findings substantiated the pivotal role of Rg1-EVs in neuronal protection and functional recovery following SCI through MYCBP2-mediated ubiquitination of S100A9. This research offers novel mechanistic insights into therapeutic strategies against SCI and supports the clinical potential of Rg1-EVs.

Spinal cord injury (SCI) is a severe disease of the nervous system that causes irreparable damage and loss of function, for which no effective treatments are available to date. Engineered extracellular vesicles (EVs) carrying therapeutic molecules hold promise as an alternative SCI therapy depending on the specific functionalized EVs and the appropriate engineering strategy. In this study, we demonstrated the design of a drug delivery system of peptide CAQK-modified, siRNA-loaded EVs (C-EVs-siRNA) for SCI-targeted therapy. The peptide CAQK was anchored through a chemical modification to the membranes of EVs isolated from induced neural stem cells (iNSCs). CCL2-siRNA was then loaded into the EVs through electroporation. The modified EVs still maintained the basic properties of EVs and showed favorable targeting and therapeutic effects in vitro and in vivo. C-EVs-siRNA specifically delivered siRNA to the SCI region and was taken up by target cells. C-EVs-siRNA used the inherent anti-inflammatory and neuroreparative functions of iNSCs-derived EVs in synergy with the loaded siRNA, thus enhancing the therapeutic effect against SCI. The combination of targeted modified EVs and siRNA effectively regulated the microenvironmental disturbance after SCI, promoted the transformation of microglia/macrophages from M1 to M2 and limited the negative effects of the inflammatory response and neuronal injury on functional recovery in mice after SCI. Thus, engineered EVs are a potentially feasible and efficacious treatment for SCI, and may also be used to develop targeted treatments for other diseases.

Objective:To screen plasma exosomal protein molecular markers in patients with spinal cord injury (SCI) by applying Label-Free quantification and bioinformatics analysis.Methods:Fifty plasma specimens from the First Affiliated Hospital of Nanjing Medical University (from January 2021 to June 2022) were collected from SCI patients and healthy people, respectively. Plasma exosomes were isolated using ultracentrifugation and identified by transmission electron microscopy, nanoparticle tracking analysis and western blot. Plasma exosomal differentially expressed proteins (DEPs) were analyzed using Label-Free quantitative proteomics, and DEPs were characterized, annotated, and enriched based on Gene Ontology (GO) and kyoto encyclopedia of genes and genomes (KEGG) databases. The screened DEPs were validated by western blot and enzyme linked immunosorbent assay (ELISA) using plasma exosomal specimens.Results:According to the spinal cord injury classification of the American Spinal Injury Association, 14 cases were grade A, 19 cases were grade B, 12 cases were grade C, and 5 cases were grade D. Plasma exosomes of SCI patients and control groups showed typical cup-like morphology, with diameters mainly ranging from 30-200 nm. A total of 493 exosomal proteins were identified by Label-Free quantification, and 126 proteins were screened for differential expression, of which 38 were up-regulated and 88 were down-regulated. GO annotation revealed that DEPs were mainly involved in functions such as protein activation cascade, complement activation and immune response. KEGG pathway analysis revealed that DEPs were involved in biological pathways such as complement and coagulation cascade reactions, proteasome and neurodegenerative disease pathways. Two candidate proteins, APOB and S100A9, were initially screened based on quantitative results from proteomics and bioinformatics analyses. Western blot results showed that the relative expression of S100A9 protein in plasma exosomes of 30 SCI patients (1.62±0.19) was elevated compared with that of 30 control groups (0.86±0.24), and the difference was statistically significant ( t=8.55, P<0.001), while the relative expression of APOB protein (1.06±0.13 and 1.02±0.23) were not statistically significant ( t=0.46, P=0.653). The results of ELISA analysis showed that the expression of S100A9 in plasma exosomes of patients with different degrees of SCI (grade A 197.7±11.7 pg/ml, grade B 151.7±15.2 pg/ml, grade C 136.3±14.7 pg/ml) had statistical significance ( F=69.94, P<0.001), the higher the severity of SCI, the higher the expression of S100A9 in plasma exosomes (A vs. B, q=13.11, P<0.001; A vs. C, q=15.66, P<0.001; B vs. C, q=4.19, P=0.005). Conclusion:S100A9 is a potentially valid plasma exosomal molecular marker for assessing the severity of SCI.

Osteoarthritis (OA) is a regressive joint disease that mainly affects the cartilage and surrounding tissues. Mounting studies have confirmed that the paracrine effect is related to the potential mechanism of mesenchymal stem cell (MSC) transplantation and that small extracellular vesicles (sEVs) play an imperative role in this paracrine signaling. In fact, hypoxia can significantly improve the effectiveness of MSC transplantation in various disease models. However, it remains unknown whether MSCs in the state of a hypoxic environment can enhance OA cartilage repair and whether this enhancement is mediated by sEV signaling. The primary aim of the present study was to determine whether sEVs from MSCs in the state of hypoxia (Hypo-sEVs) have a superior effect on OA cartilage repair relative to sEVs from MSCs in the normoxia (Nor-sEVs) state. By using an OA model and performing in vitro studies, we verified that Hypo-sEV treatment facilitated the proliferation, migration, and apoptosis suppression of chondrocytes to a greater extent than Nor-sEV treatment. Furthermore, we verified the functional role of sEV miR-216a-5p in the OA cartilage repair process. We also identified JAK2 as the target gene of sEV miR-216a-5p through a series of experiments. Our findings indicated that HIF-1α induces hypoxic BMSCs to release sEVs, which promote the proliferation, migration, and apoptosis inhibition of chondrocytes through the miR-216a-5p/JAK2/STAT3 signaling pathway. Therefore, hypoxic pretreatment is a prospective and effective method to maximize the therapeutic effect of MSC-derived sEVs on OA.

Purpose This study aims to assess the nerve function deficient recovery in surgically treated patients with cervical trauma with spinal cord injury (SCI) in chronic stage and figure out prognostic predictors of improvement in impairment and function. Methods We reviewed the clinical and radiological data of 143 cervical SCI patients in chronic stage and divided into non-operative group ( n = 61) and operative group ( n = 82). The severity of neurological involvement was assessed using the ASIA motor score (AMS) and Functional Independence Measure Motor Score (FIM MS). The health-related quality of life was measured using the SF-36 questionnaire. Correspondence between the clinical and radiological findings and the neurological outcome was investigated. Results At 2-year follow-up, surgery resulted in greater improvement in AMS and FIM MS than non-operative group. Regression analysis revealed that lower initial AMS ( P = 0.000), longer duration after injury ( P = 0.022) and injury above C4 level ( P = 0.022) were factors predictive of lower final AMS. Longer duration ( P = 0.020) and injury above C4 level ( P = 0.010) were associated with a lower FIM MS. SF-36 scores were significantly lower in higher age ( P = 0.015), female patients ( P = 0.009) and patients with longer duration ( P = 0.001). Conclusion It is reasonable to consider surgical decompression in patients with cervical SCI in chronic stage and persistent spinal cord compression and/or gross cervical instability. Initial AMS, longer duration, injury above C4 level, higher age and female patients are the five major relevant factors of functional recovery.

BACKGROUND:In the aging population, osteoporosis and related complications have become a global public health problem. Osteoporotic vertebral compression fractures are among the most common type of osteoporotic fractures and patients are at risk of secondary vertebral compression fracture.OBJECTIVES:To identify risk factors for secondary vertebral compression fracture following primary osteoporotic vertebral compression fractures.STUDY DESIGN:Retrospective study.SETTING:Department of Orthopedic, an affiliated hospital of a medical university.METHODS:This retrospective cohort study evaluated the risk factors for secondary vertebral compression fracture in 317 consecutive patients with systematic osteoporotic vertebral compression fractures who received percutaneous vertebroplasty and kyphoplasty or conservative treatment. Patients were divided into secondary vertebral compression fracture (n = 43) and non- secondary vertebral compression fracture (n = 274) groups. We retrospectively analyzed clinical characteristics and radiographic parameters, including gender, age, body mass index, number of primary fractures, primary treatment (percutaneous vertebroplasty and kyphoplasty or conservative treatment), nonspinal fracture history before primary fracture, primary fracture at the thoracolumbar junction, steroid use, bisphosphonate therapy, and Hounsfield units value of L1.RESULTS:Comparison between the groups showed significant differences in age (P = 0.001), nonspinal fracture history (P < 0.001), and Hounsfield units value of L1 (P < 0.001). The receiver operating characteristic curves demonstrated that the optimal thresholds for age and Hounsfield units value of L1 were 75 (sensitivity: 55.8%; specificity: 67.5%) and 50 (sensitivity: 88.3%; specificity: 67.4%), respectively. In multivariate logistic regression analysis, nonspinal fracture history (OR = 6.639, 95% CI = 1.809 - 24.371, P = 0.004) and Hounsfield units value of L1 < 50 (OR = 15.260, 95% CI = 6.957 - 33.473, P < 0.001) were independent risk factors for secondary vertebral compression fracture.LIMITATIONS:The main limitation is the retrospective nature of this study.CONCLUSION:Patients with low Hounsfield units value of L1 or non-spinal fracture history are an important population to target for secondary fracture prevention.

Pathologically, blood-spinal-cord-barrier (BSCB) disruption after spinal cord injury (SCI) leads to infiltration of numerous peripheral macrophages into injured areas and accumulation around newborn vessels. Among the leaked macrophages, M1-polarized macrophages are dominant and play a crucial role throughout the whole SCI process. The aim of our study was to investigate the effects of M1-polarized bone marrow-derived macrophages (M1-BMDMs) on vascular endothelial cells and their underlying mechanism. Microvascular endothelial cell line bEnd.3 cells were treated with conditioned medium or exosomes derived from M1-BMDMs, followed by evaluations of endothelial-to-mesenchymal transition (EndoMT) and mitochondrial function. After administration, we found conditioned medium or exosomes from M1-BMDMs significantly promoted EndoMT of vascular endothelial cells in vitro and in vivo, which aggravated BSCB disruption after SCI. In addition, significant dysfunction of mitochondria and accumulation of reactive oxygen species (ROS) were also detected. Furthermore, bioinformatics analysis demonstrated that miR-155 is upregulated in both M1-polarized macrophages and microglia. Experimentally, exosomal transfer of miR-155 participated in M1-BMDMs-induced EndoMT and mitochondrial ROS generation in bEnd.3 cells, and subsequently activated the NF-κB signaling pathway by targeting downstream suppressor of cytokine signaling 6 (SOCS6), and suppressing SOCS6-mediated p65 ubiquitination and degradation. Finally, a series of rescue assay further verified that exosomal miR155/SOCS6/p65 axis regulated the EndoMT process and mitochondrial function in vascular endothelial cells. In summary, our work revealed a potential mechanism describing the communications between macrophages and vascular endothelial cells after SCI which could benefit for future research and aid in the development of potential therapies for SCI.

Spinal cord injury (SCI) is a devastating trauma that leads to irreversible motor and sensory dysfunction and is, so far, without effective treatment. Recently, however, nano-sized extracellular vesicles derived from preconditioned mesenchymal stem cells (MSCs) have shown great promise in treating various diseases, including SCI. In this study, we investigated whether extracellular vesicles (MEVs) derived from MSCs pretreated with melatonin (MT), which is well recognized to be useful in treating diseases, including Alzheimer's disease, non-small cell lung cancer, acute ischemia-reperfusion liver injury, chronic kidney disease, and SCI, are better able to promote functional recovery in mice after SCI than extracellular vesicles derived from MSCs without preconditioning (EVs). MEVs were found to facilitate motor behavioral recovery more than EVs and to increase microglia/macrophages polarization from M1-like to M2-like in mice. Experiments in BV2 microglia and RAW264.7 macrophages confirmed that MEVs facilitate M2-like polarization and also showed that they reduce the production of reactive oxygen species (ROS) and regulate mitochondrial function. Proteomics analysis revealed that ubiquitin-specific protease 29 (USP29) was markedly increased in MEVs, and knockdown of USP29 in MEVs (shUSP29-MEVs) abolished MEVs-mediated benefits in vitro and in vivo. We then showed that USP29 interacts with, deubiquitinates and therefore stabilizes nuclear factor-like 2 (NRF2), thereby regulating microglia/macrophages polarization. In NRF2 knockout mice, MEVs failed to promote functional recovery and M2-like microglia/macrophages polarization. We also showed that MT reduced global N6-methyladenosine (m6 A) modification and levels of the m6 A "writer" methyltransferase-like 3 (METTL3). The stability of USP29 mRNA in MSCs was enhanced by treatment with MT, but inhibited by overexpression of METTL3. This study describes a very promising extracellular vesicle-based approach for treating SCI.

BACKGROUND:For a long time, surgical difficulty is mainly evaluated based on subjective perception rather than objective indexes. Moreover, the lack of systematic research regarding the evaluation of surgical difficulty potentially has a negative effect in this field. This study was aimed to evaluate the risk factors for the surgical difficulty of anterior cervical spine surgery (ACSS). METHODS:This was a retrospective cohort study totaling 291 consecutive patients underwent ACSS from 2012.3 to 2017.8. The surgical difficulty of ACSS was defined by operation time longer than 120 min or intraoperative blood loss equal to or greater than 200 ml. Evaluation of risk factors was performed by analyzing the patient's medical records and radiological parameters such as age, sex, BMI, number of operation levels, high signal intensity of spinal cord on T2-weighted images, ossified posterior longitudinal ligament (OPLL), sagittal and coronal cervical circumference, cervical length, spinal canal occupational ratio, coagulation function index and platelet count. RESULTS:Significant differences were reported between low-difficulty and high-difficulty ACSS groups in terms of age (p = 0.017), sex (p = 0.006), number of operation levels (p < 0.001), high signal intensity (p < 0.001), OPLL (p < 0.001) and spinal canal occupational ratio (p < 0.001). Multivariate logistic regression analysis revealed that number of operation levels (OR = 5.224, 95%CI = 2.125-12.843, p < 0.001), high signal intensity of spinal cord (OR = 4.994, 95%CI = 1.636-15.245, p = 0.005), OPLL (OR = 6.358, 95%CI = 1.932-20.931, p = 0.002) and the spinal canal occupational ratio > 0.45 (OR = 3.988, 95%CI = 1.343-11.840, p = 0.013) were independently associated with surgical difficulty in ACSS. A nomogram was established and ROC curve gave a 0.906 C-index. There was a good calibration curve for difficulty estimation. CONCLUSION:This study indicated that the operational level, OPLL, high signal intensity of spinal cord, and spinal canal occupational ratio were independently associated with surgical difficulty and a predictive nomogram can be established using the identified risk factors. Optimal performance was achieved for predicting surgical difficulty of ACSS based on preoperative factors.