Intervertebral disc degeneration (IDD) is largely attributed to impaired endogenous repair. Nucleus pulposus-derived stem cells (NPSCs) senescence leads to endogenous repair failure. Small extracellular vesicles/exosomes derived from mesenchymal stem cells (mExo) have shown great therapeutic potential in IDD, while whether mExo could alleviate NPSCs senescence and its mechanisms remained unknown. We established a compression-induced NPSCs senescence model and rat IDD models to evaluate the therapeutic efficiency of mExo and investigate the mechanisms. We found that mExo significantly alleviated NPSCs senescence and promoted disc regeneration while knocking down thioredoxin (TXN) impaired the protective effects of mExo. TXN was bound to various endosomal sorting complex required for transport (ESCRT) proteins. Autocrine motility factor receptor (AMFR) mediated TXN K63 ubiquitination to promote the binding of TXN on ESCRT proteins and sorting of TXN into mExo. Knocking down exosomal TXN inhibited the transcriptional activity of nuclear factor erythroid 2-related factor 2 (NRF2) and activator protein 1 (AP-1). NRF2 and AP-1 inhibition reduced endogenous TXN production that was promoted by exosomal TXN. Inhibition of NRF2 in vivo diminished the anti-senescence and regenerative effects of mExo. Conclusively, AMFR-mediated TXN ubiquitination promoted the sorting of TXN into mExo, allowing exosomal TXN to promote endogenous TXN production in NPSCs via TXN/NRF2/AP-1 feed-forward circuit to alleviate NPSCs senescence and disc degeneration.

Objective:To investigate the role and molecular mechanism of sensory neuron-derived exosomes (nExo) in mediating intervertebral disc degeneration (IDD).Methods:A rat IDD model was constructed, with nExo injected into the intervertebral disc. After 4 weeks, the degenerative grades of operated discs were evaluated using histological staining, while the senescent phenotype of nucleus pulposus stem cells (NPSC) in the tissue was evaluated using immunofluorescence staining. For in vitro experiments, 24 hours after the treatment of nExo to NPSC, immunoblotting, flow cytometry, or senescence-associated β-galactosidase staining was applied to evaluate the senescent phenotype of NPSC. Transcriptomics analysis was applied to identify the key molecules that mediate nExo-induced cells senescence. After 4 weeks of injecting nExo and TXN into the rat tail disc degeneration model.Results:nExo increased the degenerative grades of IDD and increased the proportion of TEK +p16 + and TEK +p21 + cells (from 36.32% ±4.04%, 33.69% ±4.56% in IDD group to 56.41% ±5.26%, 50.14% ±8.49% in IDD+nExo group, respectively; t=7.420, P<0.001; t=4.184, P<0.0019, respectively) in the disc tissue. Besides, nExo promoted the expression of p16 and p21 in NPSC and increased the percentage of cells with positive senescence-associated β-galactosidase staining (from 7.32%±1.73% to 58.22%±11.38%, t=7.658, P=0.002), while the percentage of G2/M cells was downregulated (from 18.10%±1.32% to 1.60%±0.67%, t=19.290, P<0.001). Transcriptomic analysis showed that the differential genes of CTRL vs. nExo were closely related to cell senescence, and TXN was screened by intersecting the differential gene set with the cellular senescence gene sets from the published database. Furthermore, we verified that nExo decreased the content of TXN in NPSC, while exogenous TXN downregulated the expression of p16 and p21 in NPSC, reduced the positive cell rate of senescence-associated β-galactosidase staining (from 58.84%±3.99% to 21.68%±8.16%, t=7.048, P=0.021), increased the percentage of G2/M cells (from 1.21%±0.34% to 15.26%±2.60%, t=9.259, P=0.001). TXN significantly reduced the grade of disc tissue degeneration (histological score: 14.33±0.82 in the nExo group; 8.17±1.17 in the nExo+TXN group, t=10.590, P<0.001), significantly increased the content of extracellular matrix (from 10.94±4.35 μg/mg to 50.55±12.16 μg/mg, t=7.512, P<0.001), and reduced the proportion of TEK +p16 + and TEK +p21 + double-positive cells (from 54.92%±4.21% and 60.31%±9.02% to 27.93%±3.26% and 33.75%±8.07%, respectively; t=12.430, P<0.001; t=5.375, P<0.001, respectively). Conclusion:nExo promotes cell senescence and IDD by downregulating TXN in NPSC.

Objective:To investigate the prevalence of albuminuria in Chinese residents aged >35 years and its potential association with cardiovascular disease (CVD).Methods:A total of 34 647 Chinese subjects aged ≥35 years were selected by stratified multi-stage random sampling from 2012 to 2015. Data were collected through questionnaires, physical examinations, and laboratory tests. Albuminuria was categorized into 3 types according to urinary albumin-to- creatinine ratio: normal (<30 mg/g), microalbuminuria (MAU, 30-300 mg/g), and macroalbuminuria (≥300 mg/g). Measurement data were expressed as xˉ±s, and t-tests were used for comparisons between indicators. Qualitative data were expressed as rate or constituent ratio, and the χ2 test or Kruskal-Wallis test was used to examine differences. Logistic regression was used for multivariate analyses. SAS 9.4 software was used for statistical analyses, and P<0.05 was considered statistically significant. Results:The prevalence of abnormal albuminuria was 19.1%; the prevalence was 17.2% for MAU and lower in males (13.8%) than females (20.1%, P<0.01). The risk of CVD was higher among subjects with MAU ( OR=1.23, 95% CI 1.12-1.35) and macroalbuminuria ( OR=1.86, 95% CI 1.50-2.32). When MAU was complicated by hypertension and diabetes mellitus, the CVD risk was 1.76 times higher. Conclusions:The prevalence of MAU is high among Chinese subjects aged 35 years and over. Those with MAU have higher CVD risk, especially those with hypertension and diabetes mellitus.

Objective:To prepare cell membrane-coated nanovesicles with targeted delivery of toll-like receptor 4 (TLR4) agonist, and to explore the effect and mechanism of inducing the polarization of tumor-associated macrophages (TAMs) and treating osteosarcoma.Methods:TLR4 agonist loaded nanovesicles were prepared by polycarbonate membrane extruders. The morphology and size of nanovesicles were detected by transmission electron microscopy (TEM) and particle size analyzer, and the drug loading performance of the nanovesicles to TLR4 agonist was investigated. TLR4 agonist loaded nanovesicles were co-incubated with macrophages in vitro, and the targeting ability of nanovesicles to macrophages and its role in regulating the function of macrophages were detected by confocal fluorescence microscopy. In vitro experiments, a cell co-culture system was established. After the upper layer macrophages were treated by the control group, the TLR4 agonist group and the TLR4 agonist loaded nanovesicle group, the lower layer osteosarcoma cells were collected for CCK-8 and cloning formation experiments to evaluate their effects on the proliferation and migration of osteosarcoma cells. In vivo experiments, an osteosarcoma subcutaneous graft tumor model was established, and mice were randomly divided into the control group, the TLR4 agonist group, and the TLR4 agonist loaded nanovesicle group. After the treatment by caudal vein, the tumor targeting ability of nanovesicles in vivo was explored through the in vivo imaging system, and the volume of tumor tissue was continuously detected. The subcutaneous tumors were stained to detect macrophage-related markers, and their effect on the polarization of macrophages was evaluated. The TUNEL fluorescence of tumor tissues was further detected.Results:TEM showed the round shape of TLR4 agonist loaded nanovesicle and the size was about 200 nm. The co-incubation of 0.05 mg TLR4 agonist with 0.1 mg nanovesicles was the best condition for the preparation of drug-loaded nanovesicles. The drug loading efficiency was about 35% and the drug loading content was about 0.11 mg/mg. The membrane-coated nanovesicles could efficiently load and deliver TLR4 agonist. TLR4 agonist loaded nanovesicles were labeled with DiD red fluorescent dye, and then the labeled nanovesicles were co-incubated with macrophages. It was found by confocal fluorescence microscopy that DiD labeled TLR4 agonist loaded nanovesicles significantly accumulated in macrophages, and the fluorescence of M1-type macrophage marker (iNOS) was significantly enhanced, which could induce M1 polarization of macrophages. In vitro experiments, it was found that the number of osteosarcoma cells in the TLR4 agonist loaded nanovesicle group was significantly reduced under the light microscope, and the cell morphology was wrinkled and rounded. CCK-8 and cloning formation experiments showed that the proliferation and migration ability of osteosarcoma cells in the TLR4 agonist loaded nanovesicle group was significantly reduced compared with the control group and the TLR4 agonist group. A subcutaneous graft tumor model was established. In vivo imaging experiments showed that TLR4 agonist loaded nanovesicles locally accumulated in tumor tissues in vivo, but were not distributed in other organs. The growth of tumor tissue was significantly inhibited in the TLR4 agonist loaded nanovesicle group. Moreover, the fluorescence of M1-type macrophage marker (iNOS) was significantly enhanced (relative fluorescence intensity: 3.27±0.19), while the fluorescence of M2-type macrophage marker (CD163) was significantly decreased (relative fluorescence intensity: 0.14±0.04). TUNEL fluorescence staining showed that the apoptosis level of osteosarcoma cells was significantly increased (relative fluorescence intensity: 9.53±0.21).Conclusion:Membrane-coated nanovesicles could targeted deliver TLR4 agonist to osteosarcoma, induce TAMspolarization, remodel tumor immunosuppressive microenvironment, promote cell apoptosis, and effectively kill osteosarcoma.

The skeletal system, which contains bones, joints, tendons, ligaments and other elements, plays a wide variety of roles in body shaping, support and movement, protection of internal organs, production of blood cells and regulation of calcium and phosphate metabolism. The prevalence of skeletal diseases and disorders, such as osteoporosis and bone fracture, osteoarthritis, rheumatoid arthritis, and intervertebral disc degeneration, increases with age, causing pain and loss of mobility and creating a huge social and economic burden globally. Focal adhesions (FAs) are macromolecular assemblies that are composed of the extracellular matrix (ECM), integrins, intracellular cytoskeleton and other proteins, including kindlin, talin, vinculin, paxillin, pinch, Src, focal adhesion kinase (FAK) and integrin-linked protein kinase (ILK) and other proteins. FA acts as a mechanical linkage connecting the ECM and cytoskeleton and plays a key role in mediating cell-environment communications and modulates important processes, such as cell attachment, spreading, migration, differentiation and mechanotransduction, in different cells in skeletal system by impacting distinct outside-in and inside-out signaling pathways. This review aims to integrate the up-to-date knowledge of the roles of FA proteins in the health and disease of skeletal system and focuses on the specific molecular mechanisms and underlying therapeutic targets for skeletal diseases.

Objective:To summarize the clinical characteristics and prognosis of acute hyperextension spinal cord injury (SCI) in children, and to provide some recommendations for the treatment and prevention of this disease.Methods:Reviewed the data of children of SCI after sustained or repeated hyperextension of the spine at Wuhan Union Hospital and Wuhan Children's Hospital from September 2010 to September 2020. According to the American Spinal Injury Association impairment scale (AIS grade), the patients were divided into complete SCI group and incomplete SCI group. The age, symptoms and evolution after injury, neurological level of injury, imaging data, laboratory examination data, prognosis and complications of the two groups were analyzed. Retrospectively summarize the characteristics of this type of injury.Results:Forty-four cases of acute hyperextension SCI in children were included. Their age ranged from 3 to 10 years old, 95% of them were under 8 years old and 95% of them were female. There was no significant difference in age at injury and time of dance training between children with complete SCI and incomplete SCI. Back and leg pain, lower limb weakness or paresthesia, and rapidly progress to complete or incomplete SCI in a short period were typical symptoms. All blood test results anddiagnostic analysis of cerebrospinal fluid were unremarkable or negative. There was no fracture or dislocation in the whole spine. Magnetic resonance imaging showed a longitudinally extended intramedullary high-intensity signal in the thoracolumbar spinal cord. Complete SCI accounted for 60% of all cases, and the prognosis was poor with spinal cord atrophy and various complications.Conclusion:Children younger than 10 years old after sustained or repeated hyperextension of the spine may suffer acute hyperextension SCI. Children with complete SCI have poor prognosis and serious complications. Therefore, prevention of this type of injury is the best strategy.

Osteosarcoma is a malignant tumor with extreme invasiveness and metastasis as well as dismal prognosis. It is critical to rapidly find a unique therapy strategy capable of significantly improving the prognosis of osteosarcoma. Tumor immunotherapy has the potential to reawaken the immune system, restart and sustain the tumor-immune cycle in the body, resulting in the death of tumor cells. CD8+ CTL, CD4+ T cells, NK cells and NKT cells all play critical roles in tumor immunity, while humoral immunity may not only inhibit tumor growth but also enhance it. Researchers have devised various strategies to boost the immune system in recent years based on tumor immune response studies. This paper highlights and examines osteosarcoma immunotherapy from two perspectives: (1) boosting the response of patient's own immune system to the tumor; (2) exogenously improving the patient's immunological function.

Objective:To analyze the incidence and epidemiological characteristics of traumatic spinal cord injury in China in 2018.Methods:Multi-stage stratified cluster sampling was used to randomly select hospitals capable of treating patients with spinal cord injury from 3 regions，9 provinces and 27 cities in China to retrospectively investigate eligible patients with traumatic spinal cord injury admitted in 2018. National and regional incidence rates were calculated. The data of cause of injury，injury level，severity of injury，segment and type of fracture，complications，death and other data were collected by medical record questionnaire，and analyzed according to geographical region，age and gender.Results:Medical records of 4，134 patients were included in this study，with a male-to-female ratio of 2.99∶1. The incidence of traumatic spinal cord injury in China in 2018 was 50.484 / 1 million （95% CI 50.122-50.846）. The highest incidence in the Eastern region was 53.791 / 1 million （95% CI 53.217-54.365）. In the whole country，the main causes of injury were high falls （29.58%），as well as in the Western region （40.68%），while the main causes of injury in the Eastern and Central regions were traffic injuries （31.22%，30.10%）. The main injury level was cervical spinal cord in the whole country （64.49%），and the proportion of cervical spinal cord injury in the Central region was the highest （74.68%），and the proportion of lumbosacral spinal cord injury in the Western region was the highest （32.30%）. The highest proportion of degree of injury was incomplete quadriplegia （55.20%），and the distribution pattern was the same in each region. A total of 65.87% of the patients were complicated with fracture or dislocation，77.95% in the Western region and only 54.77% in the Central region. In the whole country，the head was the main combined injury （37.87%），as well as in the Eastern and Central regions，while the proportion of chest combined injury in the Western region was the highest （38.57%）. A total of 32.90% of the patients were complicated with respiratory complications. There were 23 patients （0.56%） died in hospital，of which 17（73.91%） died of respiratory dysfunction. Conclusions:The Eastern region of China has a high incidence of traumatic spinal cord injury. Other epidemiological features include high fall as the main cause of injury cervical spinal cord injury as the main injury level，incomplete quadriplegia as the main degree of injury，head as the main combined injury，and respiratory complications as the main complication.

TSCI have dyskinesia and sensory disturbance that can cause various life-threaten complications. The patients with traumatic spinal cord injury (TSCI), seriously affecting the quality of life of patients. Based on the epidemiology of TSCI and domestic and foreign literatures as well as expert investigations, this expert consensus reviews the definition, injury classification, rehabilitation assessment, rehabilitation strategies and rehabilitation measures of TSCI so as to provide early standardized rehabilitation treatment methods for TSCI.

Since December 2019, novel coronavirus pneumonia (NCP) has been reported in Wuhan, Hubei Province, and spreads rapidly to all through Hubei Province and even to the whole country. The virus is 2019 novel coronavirus (2019-nCoV), never been seen previously in human, but all the population is generally susceptible. The virus spreads through many ways and is highly infectious, which brings great difficulties to the prevention and control of NCP. Based on the needs of orthopedic trauma patients for emergency surgery and review of the latest NCP diagnosis and treatment strategy and the latest principles and principles of evidence-based medicine in traumatic orthopedics, the authors put forward this expert consensus to systematically standardize the clinical pathway and protective measures of emergency surgery for orthopedic trauma patients during prevention and control of NCP and provide reference for the emergency surgical treatment of orthopedic trauma patients in hospitals at all levels.