Endoplasmic reticulum stress-mediated autophagy alleviates lipopolysaccharide-induced nucleus pulposus cell pyroptosis by inhibiting CHOP signaling in vitro.

Pyroptosis, a newly discovered pro-inflammatory programmed necrosis of cells, serves as an initiating and promoting event that leads to intervertebral disc (IVD) degeneration (IDD). Endoplasmic reticulum stress (ERS) and autophagy are vital regulatory mechanisms of cellular homeostasis, which is also closely related to IDD. However, the role and relationship of ERS and autophagy in the pyroptosis of nucleus pulposus cell (NPC) are not well understood. In this research, we aimed to elucidate the role and mechanism of ERS-C/EBP homologous protein (CHOP) in lipopolysaccharide (LPS)-induced cell pyroptosis and determine its interaction with autophagy. ERS and autophagy inducers or inhibitors were used or not in the preconditioning of rat NPCs. Cell viability, pyroptosis-related protein expression, caspase-1 activity assay, and enzyme-linked immunosorbent assay were performed to observe rat NPC pyroptosis after the treatment of LPS. Activation of the ERS pathway and autophagy were assessed by quantitative real-time PCR, western blot analyses, and immunofluorescence staining assay to classify the molecular mechanisms. Our results showed that LPS stimulation induced NPC pyroptosis with concomitant activation of the ERS-CHOP pathway and initiated autophagy. Activation of the ERS-CHOP pathway exacerbated rat NPC pyroptosis, whereas autophagy inhibited cell pyroptosis. LPS-induced cell pyroptosis and CHOP upregulation were negatively regulated by autophagy. LPS-induced autophagy was depressed by the ERS inhibitor but aggravated by the ERS inducer. Taken together, our findings suggested that LPS induced NPC pyroptosis by activating ERS-CHOP signaling and ERS mediated LPS-induced autophagy, which in turn alleviated NPC pyroptosis by inhibiting CHOP signaling.

Instrumented fusion versus instrumented non-fusion following expansive open-door laminoplasty for multilevel cervical ossification of the posterior longitudinal ligament.

PURPOSE: To compare the outcomes of expansive open-door laminoplasty with instrumented fusion (ELIF) and expansive open-door laminoplasty with instrumented non-fusion (ELINF) for multilevel cervical ossification of the posterior longitudinal ligament (OPLL). METHODS: Patients who underwent ELIF or ELINF due to multilevel cervical OPLL from June 2013 to June 2019 were identified. Clinical and radiological outcomes were compared between the two groups. RESULTS: A total of 78 patients were enrolled in this study with a minimum follow-up of 24 months, including 42 patients in the ELIF group and 36 patients in the ELINF group. At the final follow-up, sagittal vertical axis (SVA) and C2-C7 Cobb angle in the ELIF group were significantly better than those in the ELINF group, and cervical range of movement (ROM) in the ELIF group decreased significantly than that in the ELINF group. The incidence of OPLL progression at the final follow-up was 4.76% (2/42) in the ELIF group and 27.78% (10/36) in the ELINF group. Postoperative Japanese Orthopaedic Association (JOA) score, neck disability index (NDI), and visual analog scale (VAS) score improved significantly in each group, but JOA score and recovery rate (RR) in the ELIF group were significantly better than those in the ELINF group at the final follow-up. When K-line was positive, the difference in the final JOA score between the two groups was not significant, but the RR in the ELIF group was significantly better than that in the ELINF group. When K-line was negative, the final JOA score and RR in the ELIF group were significant higher than those in the ELINF group. CONCLUSIONS: ELIF and ELINF were two effective surgical procedures for treating multilevel cervical OPLL. However, ELIF was superior to ELINF due to better postoperative JOA score and RR, significant improvement of C2-C7 Cobb angle and maintenance of SVA, and suppressant effect on OPLL progression, especially for patients with K-line ( - ) OPLL.

A20 attenuates pyroptosis and apoptosis in nucleus pulposus cells via promoting mitophagy and stabilizing mitochondrial dynamics.

BACKGROUND: A20 is an anti-inflammatory molecule in nucleus pulposus (NP) cells. The anti-inflammatory properties of A20 are mainly attributed to its ability to suppress the NF-κB pathway. However, A20 can protect cells from death independently of NF-κB regulation. This study aimed to investigate the effects of A20 on pyroptosis and apoptosis of NP cells induced by lipopolysaccharide (LPS). METHODS: NP cells induced by LPS were used as an in vitro model of the inflammatory environment of the intervertebral disc. Pyroptosis, apoptosis, and mitophagy marker proteins were detected. Then, NP cells were transfected with A20 overexpressed lentivirus or A20-siRNA. Annexin V FITC/PI, Western blotting, and immunofluorescence assays were used to detect the apoptosis, pyroptosis, and mitophagy of NP cells. Furthermore, the expressions of A20, related proteins, and related inflammatory cytokines were detected by western blotting, and ELISA. RESULTS: Apoptosis and pyroptosis of NP cells increased gradually treated with LPS for 12 h, 24 h, and 48 h. Differently, the level of mitophagy increased first and then decreased, and was the highest at LPS treatment for 12 h. Overexpression or knockdown of A20 in NP cells revealed that A20 attenuated the pyroptosis, apoptosis, and production of inflammatory cytokines of NP cells induced by LPS, while A20 sponsored mitophagy, reduced ROS production and collapse of mitochondrial membrane potential (ΔΨm). Moreover, A20 also promoted mitochondrial dynamic homeostasis and attenuated LPS-induced excessive mitochondrial fission. Excitingly, inhibition of mitophagy attenuated the effect of A20 on the negative regulation of pyroptosis of NP cells induced by LPS. Pyroptosis was accompanied by a large release of inflammatory cytokines. Inhibition of pyroptosis also significantly reduced apoptosis of NP cells. Finally, The mitochondria-targeted active peptide SS-31 inhibited LPS-induced pyroptosis and ROS production in NP cells. CONCLUSIONS: To sum up, A20 attenuates pyroptosis and apoptosis of NP cells via promoting mitophagy and stabilizing mitochondrial dynamics. Besides, A20 reduces LPS-induced NP cell apoptosis by inhibiting NLRP3 inflammasome-mediated pyroptosis. It provides theoretical support for the reduction of functional NP cell loss in the intervertebral disc through the gene-targeted intervention of A20.

Unfolded protein response alleviates acid-induced premature senescence by promoting autophagy in nucleus pulposus cells.

Acid-induced cellular senescence is a critical underlying mechanism of intervertebral disc (IVD) degeneration (IDD). Acid stimulation activates a variety of biological changes including autophagy, endoplasmic reticulum stress, and related unfolded protein response (UPR), which are important regulators of cellular senescence. However, the precise mechanism of acid-mediated UPR and autophagy in nucleus pulposus cell (NPC) senescence has not been fully elucidated. In this study, we used acid to mimic the acidic microenvironment of IVD, and rat NPCs were cultured with or without autophagy or UPR signaling small-interfering RNAs. The related proteins and genes were assessed by immunofluorescence staining assay, Western blot analyses, and quantitative real-time polymerase chain reaction to monitor the activation of these signals and classify the molecular mechanisms underlying the correlation between autophagy and UPR pathway. Cell cycle analyses, senescence-associated ß-galactosidase staining, gene expression, and immunoblotting analyses were performed to observe NPC senescence. Results showed that acid stimulation not only induced NPC senescence, but also initiated UPR and autophagy. Silencing the binding immunoglobulin protein signaling of UPR or autophagy signaling promoted rat NPC senescence. Knock-down of the UPR also blocked NPC autophagy. Taken together, UPR inhibits NPC senescence under acidic condition by activating autophagy. Hence, UPR-dependent autophagy could be an effective biologic target for the treatment of IDD in the future.

Precise targeting of miR-141/200c cluster in chondrocytes attenuates osteoarthritis development.

OBJECTIVES: Despite preclinical studies involving miRNA therapeutics conducted in osteoarthritis (OA) over the years, none of these miRNAs have yet translated to clinical applications, owing largely to the lack of efficient intra-articular (IA) delivery systems. Here, we investigated therapeutic efficacy of the chondrocyte-specific aptamer-decorated PEGylated polyamidoamine nanoparticles (NPs)-based miRNAs delivery for OA. METHODS: The role of miR-141/200c cluster during skeletal and OA development was examined by miR-141/200cflox/flox mice and Col2a1-CreERT2; miR-141/200cflox/flox mice. Histological analysis was performed in mouse joints and human cartilage specimens. Chondrocyte-specific aptamer-decorated NPs was designed, and its penetration, stability and safety were evaluated. OA progression was assessed by micro-CT analysis, X-ray and Osteoarthritis Research Society International scores after destabilising the medial meniscus surgery with miR-141/200c manipulation by NPs IA injection. Mass spectrometry analysis, molecular docking and molecular dynamics simulations were performed to investigate the interaction between aptamer and receptor. RESULTS: Increased retention of NPs inside joint space is observed. The NPs are freely and deeply penetrant to mice and human cartilage, and unexpectedly persist in chondrocytes for at least 5 weeks. OA chondrocytes microenviroment improves endo/lysosomal escape of microRNAs (miRNAs). Therapeutically, IA injection of miR-141/200c inhibitors provides strong chondroprotection, whereas ectopic expression of miR-141/200c exacerbates OA. Mechanistically, miR-141/200c promotes OA by targeting SIRT1, which acetylates histone in the promoters of interleukin 6 (IL-6), thereby activating IL-6/STAT3 pathway. CONCLUSIONS: Our findings indicate that this nanocarrier can optimise the transport kinetics of miR-141/200c into chondrocytes, fostering miRNA-specific disease-modifying OA drugs development.

Radiological risk factors for recurrent lumbar disc herniation after percutaneous transforaminal endoscopic discectomy: a retrospective matched case-control study.

PURPOSE: To investigate radiological risk factors for recurrent lumbar disc herniation (rLDH) after percutaneous transforaminal endoscopic discectomy (PTED). METHODS: Patients who underwent PTED due to a single-level L4-L5 or L5-S1 disc herniation from January 2013 to May 2019 were enrolled in this study. A matched case-control design was carried out in a single institution. Cases were defined as those who developed rLDH, and controls were matched from those patients without rLDH according to corresponding clinical characteristics. The radiological parameters were compared between two groups. The radiological risk factors for rLDH after PTED were identified by univariate and multivariate logistic regression analysis. RESULTS: A total of 2186 patients who underwent PTED at L4-L5 or L5-S1 level were enrolled in this study. Sixty-eight patients were diagnosed with rLDH, and 136 patients were selected from the remaining 2118 nonrecurrent patients as matched controls. Univariate analysis demonstrated that herniation type (P = 0.009), surgical-level disc degeneration (P < 0.001), adjacent-level disc degeneration (P = 0.017), disc height index (DHI) (P = 0.003), and sagittal range of motion (sROM) (P < 0.001) were significantly related to rLDH. Multiple logistic regression analysis showed that low grade of surgical-level disc degeneration (P < 0.001), senior grade of adjacent-level disc degeneration (P < 0.001), a high DHI (P = 0.012), and a large sROM (P < 0.001) were the radiological independent risk factors. CONCLUSION: This study showed that low grade of surgical-level disc degeneration, senior grade of adjacent-level disc degeneration, a high DHI, and a large sROM were the radiological independent risk factors for rLDH after PTED.

Treatment of closed subtalar joint dislocation: A case report and literature review.

Subtalar dislocation is defined as a separation of the talocalcaneal and talonavicular articulations, commonly caused by high-energy mechanisms, which include falls from height, motor vehicle crashes, and twisting leg injuries. The dislocations are divided into medial, lateral, anterior, and posterior types on the basis of the direction in which the distal part of the foot has shifted in relation to the talus. The most common type is medial dislocation resulted from inversion injury. Subtalar dislocation may accompany with other fractures. Physical examination must be performed carefully to assess for neurovascular compromise. Most of the subtalar dislocations can be treated with closed reduction under sedation. If this is not possible, open reduction without further delay should be conducted. After primary treatment, X-ray and computed tomography scan should be performed to evaluate the alignment and the fractures. We report a 37-year-old male patient sustained a subtalar dislocation without any bony injury when he was playing football. The patient was successfully treated by closed reduction, and a good alignment was observed at the last follow-up. The pathogenesis and treatment method of this case were analyzed, and the related literature were reviewed, which provided a reference for future clinical treatment.

Protein kinase RNA-like ER kinase/eukaryotic translation initiation factor 2α pathway attenuates tumor necrosis factor alpha-induced apoptosis in nucleus pulposus cells by activating autophagy.

Cellular loss induced by tumor necrosis factor alpha (TNF-α) contributes to the pathogenesis of intervertebral disc (IVD) degeneration. Cellular stress induced by TNF-α activates several processes to restore cell homeostasis. These processes include autophagy, endoplasmic reticulum stress, and related unfolded protein response (UPR). However, the effect and mechanism of UPR and autophagy regulated by TNF-α in IVD degeneration (IDD) remain unclear. The effect of autophagy on biological changes in nucleus pulposus cells (NPCs) also remains elusive. In this study, rat NPCs were cultured with TNF-α in the presence or absence of the UPR or autophagy pathway small-interfering RNAs. The associated genes and proteins were evaluated through immunofluorescence staining, quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analyses to monitor UPR and autophagy signaling and identify the regulatory mechanism of autophagy by the UPR pathway. Trypan blue exclusion assay, cell flow cytometry, terminal deoxynucleotidyl transferase dUTP nick end labeling staining, qRT-PCR, and western blot analyses were performed to examine the apoptosis of NPCs. The results showed that the acute exposure of TNF-α induced the apoptosis of rat NPCs and activated the protein kinase RNA-like ER kinase/eukaryotic translation initiation factor 2α (PERK/eIF2α) pathway of UPR and initiated autophagy. Silencing the PERK/eIF2α pathway or inhibiting autophagy enhanced the apoptosis of NPCs. Interference of the PERK/eIF2α pathway suppressed the autophagy of rat NPCs under TNF-α stimulation. Taken together, the PERK/eIF2α pathway reinforces the survival of NPCs under TNF-α stimulation by activating autophagy. Therefore, PERK/eIF2α-dependent autophagy could be a novel biological therapeutic target for IDD.

Survival analysis of patients with spinal chordomas.

This study was aimed to analyze the survival of patients with spinal chordomas. Patients' data in the Surveillance, Epidemiology, and End Results (SEER) database were retrieved and analyzed statistically. There were 765 patients with spinal chordomas between 1974 and 2013. The overall survival did not improve significantly over decades for patients receiving surgery and radiotherapy (SR) (P = 0.221). There were significant differences in overall survival among subgroups of patients receiving surgery (S), radiotherapy (R), and neither S nor R (NSR) (P = 0.031, 0.037, and 0.031, respectively). Cancer-specific survival did not change significantly among subgroups of patients receiving R (P = 0.411), while it increased steadily among subgroups of patients receiving S, SR, and NSR (P < 0.001, 0.001, and 0.049, respectively). In the multivariate Cox regression model, younger onset age (hazard ratio [HR] 1.052, P < 0.001), surgery (HR 0.291, P = 0.001), and tumor location of the sacrum (HR 0.401, P = 0.002) were associated with a better overall survival. Similarly, younger onset age (HR 1.036, P = 0.029), surgery (HR 0.221, P = 0.009), and tumor location of the sacrum (HR 0.287, P = 0.002) were also associated with a higher cancer-specific survival. The changes in overall and cancer-specific survival over time differ among different treatment groups. Younger onset age, surgical strategy, and tumor location of the sacrum may be correlated with a higher overall and cancer-specific survival.

A histocytological and radiological overview of the natural history of intervertebral disk: from embryonic formation to age-related degeneration.

PURPOSE: To elucidate the natural history of intervertebral disk (IVD) and characterize its embryonic beginnings and age-related degeneration. METHODS: Coronal sections of embryonic (E13.5-neonatal) and postnatal (4-60-week-old) Sprague-Dawley rat IVD were stained by a series of histological stainings (hematoxylin and eosin, Alcian blue, Picrosirius red, Masson, Periodic acid-Schiff). Growth kinetics within embryonic IVD were evaluated by immunohistochemical staining of Ki67 and proliferating cell nuclear antigen. Postnatal maturation and degeneration of IVD were visualized on radiology by X-ray, CT, and MR imaging. RESULTS: During the formation of rat IVD, inner annulus fibrosus (AF) and cartilaginous endplate (CEP) shared similar cell density, extracellular matrix, and potential of growth kinetics; notochord provided increased and enlarged cytoplasmic vacuoles to generate nucleus pulposus (NP), part of which was retained within CEP. Postnatally, vacuolated notochord cells were reduced by devacuolation, while chondrocytic NP cells increased; cartilaginous layers of CEP were narrowed by vertebrae growth and secondary ossification; fibrotic portion of AF decreased as cartilaginous matrix accumulated and infiltrated outward. In aged and degenerated IVD, large longitudinal fissures were detected near the boundaries between inner and outer AF, whereas both reduced cellularity and accumulated cell clusters were evident within the dehydrated NP; only part of these histocytological changes could be reported on radiology. CONCLUSIONS: By showing that the natural history of IVD is orchestrated by a dynamic histocytological regulation, our study may facilitate better understanding of the developmental defects, cellular heterogeneity, age-related degenerative mechanisms, and biological regeneration of IVD. These slides can be retrieved under Electronic Supplementary Material.

Comparison of percutaneous endoscopic lumbar discectomy versus microendoscopic discectomy for the treatment of lumbar disc herniation: a meta-analysis.

PURPOSE: We conducted a systematic review and meta-analysis to compare the clinical outcomes of percutaneous endoscopic lumbar discectomy (PELD) and microendoscopic discectomy (MED) for the treatment of lumbar disc herniation (LDH), and to clarify whether PELD is more superior to MED. METHODS: We performed a comprehensive search in the databases of MEDLINE, EMBASE, PubMed, Web of Science, Cochrane database, CNKI, and Wanfang Data to acquire all relevant studies up to July 2018. The searched literatures were then screened according to the strict inclusion and exclusion criteria. The critical data were extracted and analyzed utilizing Review Manager software. The pooled effects were calculated by mean difference (MD) or odds ratio (OR) with 95% confidence intervals (CI) on the basis of data attributes. RESULTS: A total of 18 studies (2161 patients, 1093 in the PELD group and 1068 in the MED group) were included in this systematic review and meta-analysis. At last follow-up, the results revealed that no significant difference was found between PELD group and MED group with respect to ODI (MD - 0.30; 95% CI - 1.02 to 0.42; P = 0.41), VAS-leg pain (MD - 0.18; 95% CI - 0.45 to 0.09; P = 0.19), VAS-unspecified (MD - 0.00; 95% CI - 0.05 to 0.04; P = 0.94), excellent & good rate (OR, 1.04; 95% CI 0.68 to 1.59; P = 0.86), total complication rate (OR, 0.96; 95% CI 0.65 to 1.43; P = 0.85), dural tear rate (OR, 0.39; 95% CI 0.10 to 1.55; P = 0.18), and residue or recurrence rate (OR, 2.22; 95% CI 1.02 to 4.83; P = 0.05). When compared to MED group, the PELD group showed significantly better results with regard to shorter length of incision (MD - 1.18; 95% CI - 1.39 to - 0.97; P < 0.00001), less blood loss (MD - 45.17; 95% CI - 64.74 to - 25.60; P < 0.00001), shorter post-operative in-bed time (MD - 59.11; 95% CI - 71.19 to - 47.04; P < 0.00001), shorter post-operative hospital stay (MD - 3.07; 95% CI - 4.81 to - 1.33; P < 0.00001), shorter total hospital stay (MD - 2.29; 95% CI - 3.03 to - 1.55; P < 0.00001), and lower VAS-back pain at last follow-up (MD - 0.77; 95% CI - 1.31 to - 0.24; P = 0.005), but with significantly worse results such as more fluoroscopy (MD 7.63; 95% CI 5.25 to 10.01; P < 0.00001) and higher re-operation rate (OR, 2.67; 95% CI 1.07 to 6.67; P = 0.04). Although no significant difference was found between the two groups in terms of duration of operation (MD 6.27; 95% CI - 2.44 to 14.98; P = 0.16) and total hospital cost (MD - 0.69; 95% CI - 12.60 to 11.23; P = 0.91), further subgroup analysis revealed that the duration of operation was significantly longer in the PELD group compared with the MED group in "Years before 2016" (MD 24.97; 95% CI 7.07 to 42.87; P = 0.006) and "Year 2016 to 2017" (MD 6.57; 95% CI 0.58 to 12.55; P = 0.03) subgroups but not in the subgroup "Year 2018" (MD - 5.66; 95% CI - 18.84 to 7.53; P = 0.40), and that the total hospital cost was significantly more in the PELD group compared with the MED group in the subgroup "Southeast of China" (MD 6.67; 95% CI 3.23 to 10.28; P = 0.0002) but not in the subgroup "Midwest of China" (MD - 8.09; 95% CI - 17.99 to 1.80; P = 0.11). CONCLUSIONS: For the treatment of LDH, both of PELD and MED can reach excellent results and no superiority was found between the two minimally invasive procedures with regard to duration of operation, ODI, VAS-leg pain, VAS-unspecified, excellent & good rate, total complication rate, dural tear rate, and residue or recurrence rate. While PELD can achieve better outcomes with respect to the length of incision, blood loss, post-operative in-bed time, post-operative hospital stay, total hospital stay, and VAS-back pain at last follow-up, however, MED showed certain advantages of less fluoroscopic times and lower re-operation rate. More practice and development are needed to make up for the deficiencies of PELD. Besides, the economic factor should also be considered according to different regions before making the treatment strategies. Well-defined randomized controlled trials with large samples are needed to further confirm these results.

Large Cytoplasmic Vacuoles within Notochordal Nucleus Pulposus Cells: A Possible Regulator of Intracellular Pressure That Shapes the Cytoskeleton and Controls Proliferation.

Degeneration of the intervertebral disc, which is closely associated with the loss of vacuolated notochordal nucleus pulposus cells (NNPC), remains a major cause of lower-back pain and motor deficiency. Being the most defining characteristic of NNPC, large cytoplasmic vacuoles not only modulate the cytoskeleton and shape cell morphology but they also respond to the disc microenvironment and regulate the biological behavior of vacuolated cells as a potent reporter of the histocytological changes that occur at the beginning of disc aging and degeneration. Here we hypothesize a model in which large cytoplasmic vacuoles primarily function to maintain a reasonable intracellular pressure (Pv) that facilitates NNPC in resisting the extracellular mechanical loading (Pe), part of which is absorbed by the extracellular matrix (Pm), forming the equation Pe = Pm + Pv. By mimicking a situation of contact-induced growth inhibition, the crowded cytoplasmic vacuoles slow down the proliferation of NNPC and restrain the generation of nonvacuolated chondrocytic nucleus pulposus cells (CNPC), whereas increased mechanical loading (↑Pe) alters cytoskeletons and breaches cytoplasmic vacuoles, which in turn weakens the vacuoles-mediated proliferation check, increases the generation of CNPC that accumulates fibrocartilaginous matrix, and rebalances the increased loading with elevated Pm (↑Pm) and lowered Pv (↓Pv), equating to ↑Pe = ↑Pm + ↓Pv. By depicting the biological function and the disappearance of the cytoplasmic vacuoles, our model highlights a mechanical exhaustion of the notochordal cell resources, which might help to elucidate the histocytological changes that initiate disc aging and degeneration.

Lumbar disc herniation treated by microendoscopic discectomy : Prognostic predictors of long-term postoperative outcome.

PURPOSE: Microendoscopic discectomy (MED) is becoming an established and effective minimally invasive surgical method for the treatment of lumbar disc herniation (LDH); however, the absence of prognostic factors for long-term outcomes after MED results in a lack of specific criteria for appropriate patient selection. Therefore, we evaluated the long-term outcomes and associated predictors in patients who underwent MED for LDH. MATERIAL AND METHODS: Baseline and follow-up data for 664 LDH patients who suffered from sciatica and underwent primary MED were reviewed retrospectively. Variables at baseline that were analyzed as potential prognostic factors included sociodemographic characteristics, clinical findings, and imaging features. Follow-up data including improvements in the Visual Analog Scale (VAS) score and Oswestry Disability Index (ODI), postoperative low back pain (LBP), reoperation, and excellent/good results according to the modified MacNab criteria were set as outcome variables for univariate and further multivariate logistic regression analyses. RESULTS: The mean follow-up period was 63.8 ± 20.0 months (range 24-96 months). On average, sufficient improvements in both the VAS score (72.8%) and ODI (63.4%) were observed. In addition, a low postoperative LBP rate (23.9%), low reoperation rate (7.1%), and high rate of excellent/good clinical outcomes (89.9%) were achieved. A multivariate analysis indicated that older age, shorter disease duration, higher preoperative VAS score, lower preoperative ODI, shorter surgical time, lower severity of disc and adjacent disc degeneration, and lower severity of lumbar multifidus atrophy contributed to superior clinical outcomes. CONCLUSION: Excellent long-term outcomes after primary MED were achieved and specific sociodemographic, clinical, and imaging variables were identified as prognostic factors that can be used to guide patient selection and clinical decision making.

A cohort study comparing the serum levels of pro- or anti-inflammatory cytokines in patients with lumbar radicular pain and healthy subjects.

PURPOSE: The factors influencing the presence or absence of pain in sciatica secondary to disc herniation remain incompletely understood. We hypothesized that the imbalance in inflammatory cytokines is implicated in the generation of pain. In our study, serum levels of pro-inflammatory and anti-inflammatory cytokines were investigated among patients with severe sciatica; the serum levels were compared with those of patients with mild sciatica and healthy subjects. METHODS: In this prospective study, blood protein levels of the pro-inflammatory cytokines, namely, interleukin-6 (IL-6), interleukin-8 (IL-8),and tumor necrosis factor-α (TNF-α), and the anti-inflammatory cytokines, namely, interleukin-4 (IL-4) and interleukin-10 (IL-10), of 58 patients with severe sciatica, 50 patients with mild sciatica, and 30 healthy control subjects were analyzed through ELISA. Physical and mental health symptoms were determined using the Oswestry Disability Index (ODI) and short form-36 (SF-36) questionnaire. Spearman rank correlation coefficient was also determined to calculate the correlation between the scores obtained from the questionnaires and the serum levels of cytokines. RESULTS: IL-6 protein was detected in the three groups and median levels were about 1.5 times higher in patients with severe sciatica than the mild sciatica group (p = 0.02) and the controls (p = 0.03). Median levels of IL-8 in sciatica patients were higher than those of the healthy controls (p = 0.001 for severe sciatica, p = 0.02 for mild sciatica). The TNF-α protein values were approximately twofold higher in the severe sciatica group than in the mild sciatica group (p < 0.01) and in the healthy control group (p < 0.01). Median levels of IL-4 were about 2.5-fold higher in mild sciatica (p < 0.01) and about twofold higher in patients with severe sciatica (p = 0.012) when compared with controls. Median protein levels of IL-10 showed a trend to be higher in patients with mild sciatica compared with severe sciatica (p < 0.01) and with healthy controls (p < 0.01). ODI was significantly correlated with IL-6 (r = 0.394, p = 0.013), TNF-α (r = 0.629, p < 0.001), and IL-10 (r = -0.415, p = 0.009). ODI was not significantly correlated with IL-4 (r = -0.174, p = 0.29) and IL-8 (r = -0.133, p = 0.418). CONCLUSIONS: These findings support our hypothesis that sciatica pain is accompanied by the imbalance in inflammatory cytokines.

The presence of stem cells in potential stem cell niches of the intervertebral disc region: an in vitro study on rats.

PURPOSE: The potential of stem cell niches (SCNs) in the intervertebral disc (IVD) region, which may be of great significance in the regeneration process, was recently proposed. To the best of our knowledge, no previous in vitro study has examined the characteristics of stem cells derived from the potential SCN of IVD (ISN). Therefore, increasing knowledge on ISN-derived stem cells (ISN-SCs) may provide a greater understanding of IVD degeneration and regeneration processes. We aimed to demonstrate the existence of ISN-SCs and to compare their characteristics with bone marrow mesenchymal stem cells (BMSCs) in vitro. METHODS: Sprague-Dawley rats (male, 10-week-old) were used in this study. ISN tissues were separated by ophthalmic surgical instruments under a dissecting microscope according to the anatomical areas. BMSCs and cells isolated from the ISN tissues were cultured and expanded in vitro. Passage 4 populations were used for further analysis with respect to colony-forming ability, cellular immunophenotype, cell cycle, stem cell-related gene expression, and proliferation and multipotential differentiation capacities. RESULTS: In general, both of ISN-SCs and mesenchymal stromal cells (MSCs) met the minimal criteria for the definition of multipotent mesenchymal stromal cells, including adherence to plastic, specific surface antigen expression, and multipotent differentiation potential. Especially, ISN-SCs even showed greater potential of osteogenesis and chondrogenesis. The ISN-SCs also expressed stem cell-related genes that were comparable to those of BMSCs, and had colony-forming and self-renewal abilities. CONCLUSIONS: To the best of our knowledge, this is the first in vitro study aimed towards determining the existence and characteristics of ISN-SCs, which belong to the MSC family and with greater osteogenic and chondrogenic abilities than BMSCs according to our data. This finding may be of great significance for additional studies that investigate the migration of ISN-SCs into the IVD, and may provide a new perspective on different biological approaches for IVD self-regeneration.

Evaluation of transforaminal endoscopic lumbar discectomy in the treatment of lumbar disc herniation.

PURPOSE: The purpose of this study was to evaluate the efficacy of transforaminal endoscopic lumbar discectomy (TELD) in the treatment of lumbar disc herniation (LDH) and to identify the relationship between TELD efficacy and age. METHODS: A total of 207 consecutive LDH patients who had undergone TELD with the THESSYS system from January 2013 to September 2014 were divided into two groups on the basis of their age, with 108 cases in the ≤ 45-year-old age group and 99 cases in the >45-year-old group. The Oswestry Disability Index (ODI) was used to quantify the pain relief. The degree of pain and disability were measured on the basis of the visual analog scale (VAS) and the modified MacNab criteria. Complications, duration of hospital stay, surgical costs, and operation time were recorded and compared between the two groups. Spearman's coefficient of rank correlation was used to assess the learning curves for TELD. RESULTS: The mean pre-operative and postoperative VAS and ODI scores significantly improved in both age ≤ 45 group and age >45 group, with no significant differences between them. In age ≤45 group, 56 % had excellent outcomes, 28 % good, 14 % fair, and 3 % poor. In the age >45 group, 51 % had excellent outcomes, 20 % good, 25 % fair, and 4 % poor. The average lengths of hospital stay for the age ≤ 45 group and age >45 group were 6.8 and 8.4 days, respectively. The mean time to return to work or normal activities was ten days for the age ≤ 45 group and 15 days for the age >45 group. The mean operative time for the age ≤ 45 group was 94 minutes and that for age >45 group was 97 minutes. The surgical cost of age ≤ 45 group was 15,480 RMB, which was lower than the 16,381 RMB of age >45 group. A total of 14 patients in the age ≤ 45 group and 13 patients in age >45 group used analgesic medications. Three and five recurrences were reported in the age ≤ 45 group and age >45, respectively. The steep learning curves of operative time plotted against the number of surgeries conducted suggest that the TELD technique can be mastered quickly in terms of reducing the duration of operation. CONCLUSIONS: The efficacy of TELD is relatively good for the selected young and elderly patients in this study. Therefore, age is not a predictor of TELD surgery-related outcomes.

Evaluation of intervertebral disc regeneration with implantation of bone marrow mesenchymal stem cells (BMSCs) using quantitative T2 mapping: a study in rabbits.

PURPOSE: The aim of the study was to investigate the curative effects of transplantation of bone marrow mesenchymal stem cells (BMSCs) on intervertebral disc regeneration and to investigate the feasibility of the quantitative T2 mapping method for evaluating repair of the nucleus pulposus after implantation of BMSCs. METHODS: Forty-eight New Zealand white rabbits were used to establish the lumber disc degenerative model by stabbing the annulus fibrosus and then randomly divided into four groups, i.e. two weeks afterwards, BMSCs or phosphate-buffered saline (PBS) were transplanted into degenerative discs (BMSCs group and PBS group), while the operated rabbits without implantation of BMSCs or PBS served as the sham group and the rabbits without operation were used as the control group. At weeks two, six and ten after operation, the T2 values and disc height indices (DHI) were calculated by magnetic resonance imaging (MRI 3.0 T), and the gene expressions of type II collagen (COL2) and aggrecan (ACAN) in degenerative discs were evaluated by real-time reverse transcription polymerase chain reaction (RT-PCR). T2 values for the nucleus pulposus were correlated with ACAN or COL2 expression by regression analysis. RESULTS: Cell clusters, disorganised fibres, interlamellar glycosaminoglycan (GAG) matrix and vascularisation were observed in lumber degenerative discs. BMSCs could be found to survive in intervertebral discs and differentiate into nucleus pulposus-like cells expressing COL2 and ACAN. The gene expression of COL2 and ACAN increased during ten weeks after transplantation as well as the T2 signal intensity and T2 value. The DHI in the BMSCs group decreased more slowly than that in PBS and sham groups. The T2 value correlated significantly with the gene expression of ACAN and COL2 in the nucleus pulposus. CONCLUSIONS: Transplantation of BMSCs was able to promote the regeneration of degenerative discs. Quantitative and non-invasive T2 mapping could be used to evaluate the regeneration of the nucleus pulposus with good sensitivity.

Adjacent-level symptomatic fracture after percutaneous vertebral augmentation of osteoporotic vertebral compression fracture: a retrospective analysis.

BACKGROUND: Vertebral augmentation is an effective and minimally invasive procedure that is used extensively worldwide for the treatment of osteoporosis vertebral compression fractures (OVCFs). New pain from adjacent vertebra fracture (AVF) after initial cement augmentation has gradually been given attention, but the exact causes of AVF are still controversial. The purpose of this study was to analyze the associated incidence, risk factors, and possible causative mechanism of symptomatic AVF, and to evaluate the intrinsic relationship between cement leakage into the disk and AVF. METHODS: Three hundred and fifty-eight patients (271 women, 87 men; mean age 70.5 ± 9.1 years; range 42-91 years) undergoing vertebral augmentation for their single level of OVCFs were enrolled in the study. Patients were divided into AVF (n = 26) and AVF-free (n = 332) groups, and the groups were compared with respect to preoperative and perioperative parameters, as well as postoperative results. Potential risk factors were evaluated using logistic regression analysis. RESULTS: The rate of symptomatic AVF was 7.3%. The majority of symptomatic AVF, 57.7% of which developed 6 months after the procedures, were located mainly in the thoraco-lumbar vertebra. Significant differences were found between the AVF and AVF-free groups with regard to age, bone mineral density (BMD), and intravertebral clefts (p < 0.05). AVF occurred in six of 28 patients with intravertebral clefts, and five of them developed AVF within 6 months after the procedure. No statistically significant association was observed in the correlation between intradiscal cement leakage and the incidence of symptomatic AVF (p = 0.390). CONCLUSIONS: Older age, lower BMD, and intravertebral clefts are the main risk factors for symptomatic AVF after vertebral augmentation, but intradiscal cement leakage does not increase the risk of AVF. AVF occurs because of the natural progression of osteoporosis. Even distribution of bone cement in the vertebral body is important in OVCF patients with intravertebral clefts.

The regulatory mechanism of cyclic GMP-AMP synthase on inflammatory senescence of nucleus pulposus cell.

BACKGROUND: Cellular senescence features irreversible growth arrest and secretion of multiple proinflammatory cytokines. Cyclic GMP-AMP synthase (cGAS) detects DNA damage and activates the DNA-sensing pathway, resulting in the upregulation of inflammatory genes and induction of cellular senescence. This study aimed to investigate the effect of cGAS in regulating senescence of nucleus pulposus (NP) cells under inflammatory microenvironment. METHODS: The expression of cGAS was evaluated by immunohistochemical staining in rat intervertebral disc (IVD) degeneration model induced by annulus stabbing. NP cells were harvested from rat lumbar IVD and cultured with 10ng/ml IL-1ß for 48 h to induce premature senescence. cGAS was silenced by cGAS specific siRNA in NP cells and cultured with IL-1ß. Cellular senescence was evaluated by senescence-associated beta-galactosidase (SA-ß-gal) staining and flow cytometry. The expression of senescence-associated secretory phenotype including IL-6, IL-8, and TNF-a was evaluated by ELISA and western blotting. RESULTS: cGAS was detected in rat NP cells in cytoplasm and the expression was significantly increased in degenerated IVD. Culturing in 10ng/ml IL-1ß for 48 h induced cellular senescence in NP cells with attenuation of G1-S phase transition. In senescent NP cells the expression of cGAS, p53, p16, NF-kB, IL-6, IL-8, TNF-α was significantly increased while aggrecan and collagen type II was reduced than in normal NP cells. In NP cells with silenced cGAS, the expression of p53, p16, NF-kB, IL-6, IL-8, and TNF-α was reduced in inflammatory culturing with IL-1ß. CONCLUSION: cGAS was increased by NP cells in degenerated IVD promoting cellular senescence and senescent inflammatory phenotypes. Targeting cGAS may alleviate IVD degeneration by reducing NP cell senescence.

Prediction Model and Risk Factor Analysis of Adjacent Segment Disease After L4-5 Transforaminal Lumbar Interbody Fusion Through Preoperative Radiographic Features.

STUDY DESIGN: A retrospective study. OBJECTIVE: To investigate the risk of adjacent segment disease (ASD) after L4-5 transforaminal lumbar interbody fusion (TLIF) in patients diagnosed with lumbar spinal stenosis (LSS), a prediction model for ASD is established and validated. METHODS: A retrospective study was carried out on a sample of 290 patients who underwent L4-5 TLIF at Zhongda Hospital, Southeast University, from January 2015 to January 2021. The study collected baseline data and preoperative radiographic features of L3-4 and L5-S1. The determination of the outcome variable was based on X-ray results spanning over 24 months and JOA scores. Multivariate logistic regression was used to identify the risk factors in constructing a nomogram. RESULTS: Independent risk factors for L3-4 degeneration after TLIF included osteoarthritis of L3-4 facet joints, L3-4 foraminal stenosis, L4 upper endplate osteochondritis, L3-4 local lordosis angle, and L3-4 spinal stenosis. Independent risk factors for L5-S1 degeneration after TLIF included osteoarthritis of L5-S1 facet joints, L5-S1 intervertebral disc degeneration, L5-S1 spinal stenosis, L5-S1 coronal imbalance, and S1 upper endplate osteochondritis. A predictive model was developed. The AUC for the prediction models at L3-4 and L5-S1 were .945 and .956. The calibration curve demonstrated good consistency between the predicted and actual probabilities. The DCA curve indicated the clinical benefit and practical value of this predictive model. CONCLUSION: This study established nomograms for postoperative degeneration at L3-4 and L5-S1 based on selected preoperative radiographic features. These models provide a valuable auxiliary decision-making system for clinicians and aid in early surgical decisions.