Retraction: Strontium-doped gelatin scaffolds promote M2 macrophage switch and angiogenesis through modulating the polarization of neutrophils.

Retraction of 'Strontium-doped gelatin scaffolds promote M2 macrophage switch and angiogenesis through modulating the polarization of neutrophils' by Tao Li et al., Biomater. Sci., 2021, 9, 2931-2946, https://doi.org/10.1039/D0BM02126A.

HMGB1 can activate cartilage progenitor cells in response to cartilage injury through the CXCL12/CXCR4 pathway.

INTRODUCTION: Recent studies have suggested that cartilage progenitor cells (CPCs) could be activated and differentiated into chondrocytes to produce matrix and to restore the integrity of damaged cartilage after injury. However, the mechanism involved in CPC activation upon damage is still unclear. This study aims to investigate the role of high mobility group box chromosomal protein 1 (HMGB1) in both activation and migration of CPCs during cartilage injury. MATERIAL AND METHODS: Explants harvested from mature bovine stifle joints were used for impact injury. The proliferation and migration of CPCs were examined via confocal imaging. Gene and protein expression of Hmbg1, Cxcl12, and Cxcr4 was also examined by quantitative polymerase chain reaction (qPCR), ELISA, and western blot. Each experiment was repeated 3 times. ANOVA and Student's t-test were performed for statistical analysis. RESULTS: HMGB1 released from dead and damaged chondrocytes after an impact injury could activate CPCs in the superficial zone of cartilage and promote their migration and proliferation to injury sites. However, the block of HMGB1 activation with its specific binding inhibitor glycyrrhizin inhibits the proliferation and migration of CPCs. Further investigations demonstrate that HMGB1 promotes CPCs migration through the pathway of C-X-C motif chemokine 12 (CXCL12) and its receptor CXCR4. Quantitative analysis of HMGB1 in cell culture medium also indicates that CPCs may have a self-activation property after the HMGB1 released from dead cells has been exhausted. CONCLUSION: HMGB1 is a pivotal factor that could enhance the migration and proliferation of CPCs through the CXCL12/CXCR4 pathway after cartilage injury, which could provide useful information for cartilage repair and osteoarthritis treatment.

Three-Dimensional Printing Model Enhances Correct Identification and Understanding of Pelvic Fracture in Medical Students.

OBJECTIVE: Understanding the anatomy behind a pelvic fracture can be a significant challenge to medical students. Recent advances in three-dimensional printing technology offers a novel approach to facilitate the learning of complex fracture. We have described here how the 3-dimension printing (3Dp) models can help medical students improve their understanding in and identification of pelvic fractures. DESIGN: One hundred students were randomized into 2 teaching module groups (with or without 3Dp models). Prior to randomization assignment, a 50-minute didactic lecture covering elementary knowledge of anatomy, Young-Burgess classification, and traumatic mechanism of pelvic fracture was delivered to all students. The 3Dp group received X-rays, CT images, and 3Dp models of the eight pelvic fractures during presentation, while the students in the control group only obtained X-rays and CT scans of the same 8 pelvic fractures. Young-Burgess classification system and injury mechanism of pelvic fracture, time for evaluation, and subjective questions were conducted to assess the learning outcomes. SETTING: A medical student program based in a LevelⅠtrauma center PARTICIPANTS: One hundred students in their 4th year of a 5-year clinical medicine program (for a medical bachelor degree) RESULTS: Students receiving 3Dp model had a higher rate of identifying the correct pelvic fracture via Young-Burgess identification compared to these without 3Dp model. Moreover, the accuracy of identifying the injury mechanism was significantly higher in the 3Dp group than that in group without 3Dp model. Participant in 3Dp group had faster assessment time compared to the control group. Subjective survey results suggested that 3Dp model would increase the learning interest and enhance the understanding of pelvic fracture. In addition, majority of students (83%) reported that they would like to use 3Dp model in other surgical course education. CONCLUSIONS: 3Dp model increased the perceived accuracy of pelvic fracture identification and understanding of injury mechanism. Moreover, 3Dp model promoted the subjective interest and motivation of students in pelvic fracture learning. Therefore, 3Dp model can be considered as a valuable educational tool for learning pelvic fracture in medical students.

Biomechanical study on parallel cannulated compression screw combined with medial buttress plate fixation and F-type cannulated compression screw fixation in Pauwels III femoral neck fracture：A finite element analysis. / å¹³è¡Œç©ºå¿ƒåŠ åŽ‹èžºé’‰è”åˆå† ä¾§æ”¯æ’‘é’¢æ¿ä¸ŽFåž‹ç©ºå¿ƒåŠ åŽ‹èžºé’‰å›ºå®šPauwels IIIåž‹è‚¡éª¨é¢ˆéª¨æŠ˜ç”Ÿç‰©åŠ›å­¦ç‰¹æ€§çš„æœ‰é™å ƒåˆ†æž.

OBJECTIVES: Pauwels III fracture is a kind of femoral neck fractures, in which the angle of the fracture line in the coronal plane and the upper edge of the acetabulum is more than 50°. Internal fixation for the treatment of femoral neck fractures is largely performed by cannulated compression screw (CCS), dynamic hip screw, or locking plate. This study aims to compare the biomechanical properties of parallel CCS combined with medial buttress plate fixation and F-type CCS fixation in the treatment of Pauwels III femoral neck fracture by finite element modeling and to determinate the most suitable procedure for such fractures. METHODS: A 52-year-old male volunteer, 176 cm in height and 72 kg in weight, with no history of hip joint, was selected. X-ray and CT examination confirmed that the morphology and bone condition of the right hip of the volunteer were normal. A simulation model of Pauwels III femoral neck fracture was established from the collected CT data of the right proximal femur of the volunteer by the finite element method. Four internal fixations were developed to treat the finite element model: Three CCSs in an inverted triangular parallel configuration combined with medial buttress plate model served as Group A, 2 CCSs in a vertical parallel configuration combined with medial buttress plate model served as Group B, 2 CCSs in a horizontal parallel configuration combined with medial buttress model served as Group C, and the "F" shaped CCS model served as Group D. The distribution of stress, the peak stress, the distribution and maximum of displacement of internal fixations and fracture ends in different models were evaluated. RESULTS: For Groups A, B, C, and D, the peak stresses on the internal fixation were 362.74, 586.84, 558.25, and 208.66 mPa, respectively, all of which occurred near the fractures and the stress distribution in Group D was the most uniform. The maximum displacements of internal fixations in Groups A, B, C, and D were 0.39, 0.45, 0.44, and 0.41 mm, respectively; the peak stresses on the fracture ends were 70.62, 98.48, 55.84, and 65.39 mPa, respectively, all of which were concentrated on the base of femoral neck and lateral cortex of the femoral shaft, and the stresses of Groups C and D were more evenly distributed than those of Groups A and B. The maximum displacements of fracture ends in Groups A, B, C, and D were 0.44, 0.52, 0.50, and 0.44 mm, respectively. CONCLUSIONS: The biomechanical stability of F-type CCS fixation is similar to that of 3 CCSs in an inverted triangular parallel configuration combined with medial buttress plate, with a better dispersion of stress. F-type CCS fixation may be a well option for the treatment of femoral neck fracture of Pauwels III.

Single Modified Posterior Approach through the Space of the Proximal Radioulnar Joint for Terrible Triad Injury: A Comparative Study.

OBJECTIVE: In order to reduce surgical scars and the risk of neurovascular injury for the treatment of terrible triad injuries of the elbow (TTI), minimally invasive and better therapeutic effect approaches are being explored to replace the conventional combined lateral and medial approach (CLMA). This study was performed to compare the clinical effect and security of the modified posterior approach (MPA) through the space of the proximal radioulnar joint vs the CLMA for treatment of TTI. METHODS: This study retrospectively analyzed 76 patients treated for TTI from January 2009 to December 2020 (MPA: n = 44; CLMA: n = 32). Treatment involved plate and screw fixation or Steinmann pin fixation for the radial head and ulnar coronoid process fractures. Surgeons only sutured the lateral ligament because the medial collateral ligament was usually integrated in the TTI. The continuous variables were compared by the independent Student t-test and the categorical variables by the χ2 -test or Fisher's exact test. RESULTS: Both groups of patients attained a satisfactory MEPS after the operation. The MEPS (MPA: 96.82 ± 6.04 vs CLMA: 96.56 ± 5.51) was not significantly different between the two groups (p > 0.05). However, the MPA resulted in better elbow flexion and extension (MPA: 123.98 ± 10.09 vs CLMA: 117.66 ± 8.29), better forearm rotation function (MPA: 173.41 ± 6.81 vs CLMA: 120.00 ± 12.18), and less intraoperative hemoglobin (MPA: 9.34 ± 5.64 vs CLMA: 16.5 ± 8.75) and red cell volume loss (MPA: 3.09 ± 2.20 vs CLMA: 6.70 ± 2.97) (All p < 0.05). Although the CLMA had a shorter surgery time (MPA: 171.73 ± 80.68 vs CLMA: 130.16 ± 71.50) (p < 0.05), it had a higher risk of neurologic damage (MPA: 0 vs CLMA: 4) (p < 0.05). Four patients developed forearm or hand numbness after the CLMA, but no patients developed numbness after the MPA. All 76 patients were followed up for 15 months postoperatively. CONCLUSION: The MPA through the space of the proximal radioulnar joint has more prominent advantages than the CLMA for TTI, including single scar, clear exposure, good fixation, lower risk of neurovascular injury, and better elbow joint motion. It is a safe and effective surgical approach that is worthy of clinical promotion.

Sequential activation of M1 and M2 phenotypes in macrophages by Mg degradation from Ti-Mg alloy for enhanced osteogenesis.

BACKGROUND: Even though the modulatory effects of Magnisum (Mg) and its alloys on bone-healing cells have been widely investigated during the last two decades, relatively limited attention has been paid on their inflammation-modulatory properties. Understanding the activation process of macrophages in response to the dynamic degradation process of Mg as well as the relationship between macrophage phenotypes and their osteogenic potential is critical for the design and development of advanced Mg-based or Mg-incorporated biomaterials. METHODS: In this work, a Ti-0.625 Mg (wt.%) alloy fabricated by mechanical alloying (MA) and subsequent spark plasma sintering (SPS) was employed as a material model to explore the inflammatory response and osteogenic performance in vitro and in vivo by taking pure Ti as the control. The data analysis was performed following Student's t-test. RESULTS: The results revealed that the macrophages grown on the Ti-0.625 Mg alloy underwent sequential activation of M1 and M2 phenotypes during a culture period of 5 days. The initially increased environmental pH (~ 8.03) was responsible for the activation of M1 macrophages, while accumulated Mg2+ within cells contributed to the lateral M2 phenotype activation. Both M1 and M2 macrophages promoted osteoblast-like SaOS-2 cell maturation. In vivo experiment further showed the better anti-inflammatory response, regenerative potentiality and thinner fibrous tissue layer for the Ti-0.625 Mg alloy than pure Ti. CONCLUSION: The results highlighted the roles of Mg degradation in the Ti-0.625 Mg alloy on the sequential activation of macrophage phenotypes and the importance of modulating M1-to-M2 transition in macrophage phenotypes for the design and development of inflammation-modulatory biomaterials.

Association between inflammatory cytokines and anti-SARS-CoV-2 antibodies in hospitalized patients with COVID-19.

BACKGROUND: COVID-19 patients may experience "cytokine storm" when human immune system produces excessive cytokines/chemokines. However, it remains unclear whether early responses of inflammatory cytokines would lead to high or low titers of anti-SARS-CoV-2 antibodies. METHODS: This retrospective study enrolled a cohort of 272 hospitalized patients with laboratory-confirmed SARS-CoV-2. Laboratory assessments of serum cytokines (IL-2R, IL-6, IL-8, IL-10, TNF-α), anti-SARS-CoV-2 IgG/IgM antibodies, and peripheral blood biomarkers were conducted during hospitalization. RESULTS: At hospital admission, 36.4% patients were severely ill, 51.5% patients were ≥ 65 years, and 60.3% patients had comorbidities. Higher levels of IL-2R and IL-6 were observed in older patients (≥65 years). Significant differences of IL-2R (week 2 to week ≥5 from symptom onset), IL-6 (week 1 to week ≥5), IL-8 (week 2 to week ≥5), and IL-10 (week 1 to week 3) were observed between moderately-ill and severely ill patients. Anti-SARS-CoV-2 IgG titers were significantly higher in severely ill patients than in moderately ill patients, but such difference was not observed for IgM. High titers of early-stage IL-6, IL-8, and TNF-α (≤2 weeks after symptom onset) were positively correlated with high titers of late-stage IgG (≥5 weeks after symptom onset). Deaths were mostly observed in severely ill older patients (45.9%). Survival analyses revealed risk factors of patient age, baseline COVID-19 severity, and baseline IL-6 that affected survival time, especially in severely ill older patients. CONCLUSION: Early responses of elevated cytokines such as IL-6 reflect the active immune responses, leading to high titers of IgG antibodies against COVID-19.

The Effect of Bisphosphonates on Fracture Healing Time and Changes in Bone Mass Density: A Meta-Analysis.

Background: Osteoporosis is a common complication of acute fracture, which can lead to fracture delayed union or other complications and resulting in poor fracture healing. Bisphosphate is a common anti-osteoporosis drug, but its application in fracture patients is still controversial because of its inhibitory effect on bone resorption. Method: Studies were acquired from literature databases in accordance with established inclusion criteria. Standard mean difference (SMD) and 95% confidence intervals (Cls) were calculated to evaluate the effectiveness of the bisphosphonates treatment in fracture patients. Data analysis was conducted with the Review Manager 5.4.1 software. Results: A total of 16 studies involving 5022 patients obtained from selected databases were examined. As expected, bisphosphate had no significant effect on fracture healing time, but it could significantly increase BMD and prevent osteoporosis. Meanwhile, bisphosphate can inhibit both bone resorption and bone formation markers, resulting in low bone turnover state. Conclusion: This meta-analysis showed that bisphosphonate have no significant effect on fracture healing time but they do increase the changes in BMD and reduce bone synthesis and resorption markers. Early application of bisphosphonates after injury in the appropriate patient population should be considered.

Old unreduced obturator dislocation of the hip: A case report.

BACKGROUND: Obturator dislocation is a rare type of hip dislocation, accounting for about 2%-5% of all hip dislocations. The occurrence of old unreduced obturator dislocation is even more infrequent, with only 17 cases reported in nine studies, most of which were from the 1950s to 1980s in developing countries. CASE SUMMARY: A 38-year-old woman from Hunan Province, China presented with stiffness of the left hip in abduction, flexion, and external rotation after falling from a 2-meter-tall tree onto her left knee 1.5 mo prior. Pelvic radiograph and computed tomography revealed obturator dislocation of the left hip accompanied by impaction fracture at the superolateral aspect of the left femoral head without associated acetabulum fracture. Open reduction was performed, resulting in restoration of the concentric alignment of the left hip. After surgery, 6-wk skin traction was applied and the patient was kept in bed for an additional 2 wk. At 3 mo after surgery, the patient reported experiencing some pain, which did not affect the function of the affected limb, and some movement restriction but no abduction deformity or claudication was present. An X-ray showed that the left hip was homocentric, and there was no sign of posttraumatic arthritis or avascular necrosis. CONCLUSION: Open reduction may be an effective treatment strategy for the rare condition of old unreduced obturator dislocation with short neglect time.

Functional interaction between Wnt and Bmp signaling in periosteal bone growth.

Wnt and Bmp proteins are well known to regulate bone development and homeostasis. Although both signals are extensively studied, their potential interaction in vivo is less well understood. Previous studies have shown that deletion of Bmpr1a, a type I receptor for Bmp signaling, results in excessive trabecular bone formation while diminishing periosteal bone growth. Moreover, forced-expression of the Wnt antagonist Sost suppresses the overgrowth of trabecular bone caused by Bmpr1a deletion, thus implicating hyperactive Wnt signaling in the excessive trabecular bone formation. However, it remains uncertain whether Wnt and Bmp signaling interacts in regulating the periosteal bone growth. Here we show that multiple Wnt genes are markedly suppressed in the cortical bone without Bmpr1a. Importantly, overexpression of Wnt7b fully rescues periosteal bone growth in the Bmpr1a-deficient mice. Thus, pharmacological activation of Wnt signaling can restore normal bone size without intact Bmp signaling.

Use of a Double Reverse Traction Repositor versus a Traction Table for the Treatment of Intertrochanteric Femur Fractures: A Comparative Study.

OBJECTIVE: The aim of the present study was to compare the clinical results for unstable femoral intertrochanteric fractures treated with a double reverse traction repositor (DRTR) and those treated using a traction table with the Asia proximal femoral nail antirotation (PFNA-II). METHODS: A retrospective study was performed including 95 patients with AO/OTA type 31-A2 and 31-A3 unstable femoral intertrochanteric fractures who underwent DRTR or traction table-facilitated PFNA-II nailing from April 2015 to December 2018 in our traumatic center. Demographics, duration of operation, blood loss, part loading time after surgery, fracture healing time, and early and late complications were assessed. Clinical and radiological outcomes were collected to compare the differences between the two groups. RESULTS: A total of 95 unstable intertrochanteric fracture patients treated with the PFNA-II were analyzed. Of these cases, 56 patients were treated with a DRTR and the other 39 patients were treated using a traction table to achieve fracture reduction. No patients died during surgery and hospitalization. There were no significant differences in respect to demographics and fracture characteristics of cases enrolled. The total operative time was significantly longer in the traction table group than in the DRTR group (72.5 ± 6.1 min for the traction table and 63.0 ± 4.1 min for the DRTR group, P < 0.001). No significant differences were observed in intraoperative blood loss and duration of hospitalization. The periods of follow up ranged from 12 to 31 months among all patients. At the last follow up, the Harris hip score (HHS) in the DRTR group was excellent in 10 patients (17.9%), good in 36 (64.3%), fair in 8 (14.3%), and poor in 2 (3.6%). These scores were comparable to those in the traction table group, which were: excellent in 8 patients (20.5%), good in 24 (61.5%), fair in 6 (15.4%), and poor in 1 (2.6%). Regarding the radiological evaluation, excellent rates of reduction rate were achieved in 39 cases (69.6%) in the DRTR group, which was comparable to 19 cases (48.7%) in the traction table group. In addition, the mean fracture healing time after surgery was 20.6 ± 2.3 weeks in the DRTR group and 21.4 ± 3.4 weeks in the traction table group, which did not reach a significant difference (P = 0.18). During the follow up, 6 cases of thigh pain, 4 cases of deep vein thrombosis, and 1 case of fracture of the anterior superior iliac spine were reported in the DRTR group. In the traction table group, there were 2 cases of deep vein thrombosis and 3 cases of thigh pain. CONCLUSION: When using the PFNA-II for unstable intertrochanteric fractures, the DRTR was superior to the traction table in respect to operative time and duration of patient position, despite an additional ipsilateral anterior superior iliac spine (ASIS) incision and drilling of the ASIS and the femur condyle.

Long non-coding RNA CIR inhibits chondrogenic differentiation of mesenchymal stem cells by epigenetically suppressing ATOH8 via methyltransferase EZH2.

BACKGROUND: Osteoarthritis (OA) is the most common articular disorder, leading to joint malfunction and disability. Although the incidence of OA is increasing globally, the treatment of OA is very limited. LncRNA CIR has been implicated in OA through unclear mechanisms. Here, we investigated the role of lncRNA CIR in chondrogenic differentiation. METHODS: Human umbilical-cord-derived mesenchymal stem cells (hUC-MSCs) were obtained from human umbilical cords. Flow cytometry was used to analyze the surface markers of hUC-MSCs. Various culture conditions and corresponding staining assays were employed to assess the differentiation abilities of hUC-MSC. qRT-PCR, western blot, and immunostaining were used to measure expression levels of related genes and proteins such as lncRNA CIR, ATOH8, EZH2, and H3K27me3. RNA immunoprecipitation assay, biotin pull-down, and chromatin immunoprecipitaion assay were performed to analyze the interactions of lncRNA CIR, EZH2, H3K27me3 and ATOH8 promoter. RESULTS: hUC-MSCs exhibited MSCs features and could differentiate into chondrocytes under specific conditions. LncRNA CIR was downregulated while ATOH8 was upregulated during the chondrogenic differentiation of hUC-MSCs. Knockdown lncRNA CIR or overexpression of ATOH8 promoted chondrogenic differentiation. Further, lncRNA CIR bound to EZH2 and repressed ATOH8 expression via EZH2-mediated H3K27me3, which promotes the methylation of ATOH8. Inhibition of ATOH8 reversed the effects of knockdown lncRNA CIR on chondrogenic differentiation. CONCLUSION: LncRNA CIR suppresses chondrogenic differentiation of hUC-MSCs. Mechanistically, lncRNA CIR could inhibit ATOH8 expression that functions to promote chondrogenic differentiation through EZH2-mediated epigenetic modifications.

Strontium-doped gelatin scaffolds promote M2 macrophage switch and angiogenesis through modulating the polarization of neutrophils.

The immune system mediates inflammation, vascularization and the first response to injuries or implanted biomaterials. Although the function of neutrophils in tissue repair has been extensively studied, its complete role in the tissue regeneration of biomaterials, specifically the resolution of inflammation and promotion of angiogenesis, is unclear. Here, we fabricate nanofibrous gelatin scaffolds containing 10% (w/w) strontium-hydroxyapatite (SrHA) via phase-separation methods to investigate Sr-mediated regulation of neutrophil polarization and, subsequently, the effects on angiogenesis and macrophage polarization. Compared with neutrophils cultured on pure gelatin or HA-incorporated gelatin scaffolds, neutrophils on SrHA-incorporated gelatin scaffolds show more N2 polarization in vitro and in vivo and significantly greater production of immunomodulatory and angiogenic factors. The Sr-induced immunomodulatory and proangiogenic functions of neutrophils are mediated through NF-κB pathway downregulation and increased STAT3 phosphorylation. Thus, neutrophils play a vital role in tissue engineering, and Sr-incorporated scaffolds efficiently promote neutrophil polarization to the N2 phenotype, enhancing resolution of inflammation and ultimately promoting angiogenesis and tissue regeneration. Thus, incorporation of neutrophils in analyses of the immune characteristics of scaffolds and the development of immunomodulatory biomaterials that can regulate neutrophils are novel and promising strategies in tissue engineering.

Modified pararectus approach for treatment of atypical acetabular anterior wall fracture: A case report.

BACKGROUND: Acetabular anterior wall fracture with preservation of the pelvic brim is extremely rare. It is different from anterior wall fracture classified by Judet and Letournel. Few studies have reported cases treated by open reduction and internal fixation via the Smith-Petersen or iliofemoral approach. CASE SUMMARY: We report a 48-year-old Chinese woman who had difficulty moving her right hip from abduction and external rotation after falling from 3 m. Pelvic radiograph and three-dimensional reconstruction of computed tomography revealed acetabular anterior wall fractures combined with fractures of the anterior inferior iliac spine and the iliac wing but not involving the pelvic brim. First, the patient underwent interim management by closed reduction of the hip dislocation and skin traction for 6 d. Then, we used a modified pararectus approach for treatment to fix the acetabular fractures with a reconstruction plate and nonlocking T-shape plate. At the 9-mo follow-up, the patient could walk painlessly without necrosis of the femoral head or heterotopic ossification, and the X-rays and computed tomography scan reconstructions showed good bone union. CONCLUSION: The modified pararectus approach described here can facilitate exposure, reduction, and osteosynthesis for atypical acetabular fracture with less invasiveness.

The regulatory effect of has-circ-0001146/miR-26a-5p/MNAT1 network on the proliferation and invasion of osteosarcoma.

Osteosarcoma is a malignant bone tumour with the lowest survival rates out of all paediatric cancers and is primarily diagnosed in children and adolescents. MNAT1 is a subunit in the cyclin-dependent kinase-activating kinase complex. Abnormal up-regulation of MNAT1 has been associated with the poor prognosis of multiple cancers. Bioinformatics analysis showed that has-circ-0001146 and miR-26a-5p were involved in the regulation of MNAT1 in osteosarcoma. The present study investigated the regulatory effects of has-circ-0001146 and miR-26a-5p on MNAT1 expression using luciferase reporter and RNA-pull down assays. The effects of the has-circ-0001146/miR26a-5p/Mnat1 network on the proliferation and invasion of osteosarcoma were evaluated by cell viability, apoptosis, migration, and invasion assays. Osteosarcoma tissues showed higher MNAT1 and has-circ-0001146 expression than adjacent normal tissues, although the expression of MNAT1 was not significantly up-regulated in sarcomas according to TCGA databases. As indicated by luciferase reporter and RNA-pull down assays, miR-26a-5p was able to bind to both has-circ-0001146 and MNAT1 mRNA. The depletion of has-circ-0001146 as well as the increase of miR-26a-5p decreased MNAT1 expression in osteosarcoma cells, while the reduction of miR-26a-5p was associated with increased MNAT1 expression. These data suggested that has-circ-0001146 promoted MNAT1 expression by competitively binding to miR-26a-5p with MNAT1 mRNA. The depletion of has-circ-0001146 or MNAT1 or the increase of miR-26a-5p inhibited osteosarcoma cell viability and invasion, and increased apoptosis. Reduction of miR-26a-5p conversely promoted osteosarcoma cell viability and invasion. The present study confirmed that has-circ-0001146 blocked miR-26a-5p targeting MNAT1 in osteosarcoma cells, thereby promoting the malignant behaviours of osteosarcoma cells.

Inducible expression of Wnt7b promotes bone formation in aged mice and enhances fracture healing.

There remain unmet clinical needs for safe and effective bone anabolic therapies to treat aging-related osteoporosis and to improve fracture healing in cases of nonunion or delayed union. Wnt signaling has emerged as a promising target pathway for developing novel bone anabolic drugs. Although neutralizing antibodies against the Wnt antagonist sclerostin have been tested, Wnt ligands themselves have not been fully explored as a potential therapy. Previous work has demonstrated Wnt7b as an endogenous ligand upregulated during osteoblast differentiation, and that Wnt7b overexpression potently stimulates bone accrual in the mouse. The earlier studies however did not address whether Wnt7b could promote bone formation when specifically applied to aged or fractured bones. Here we have developed a doxycycline-inducible strategy where Wnt7b is temporally induced in the bones of aged mice or during fracture healing. We report that forced expression of Wnt7b for 1 month starting at 15 months of age greatly stimulated trabecular and endosteal bone formation, resulting in a marked increase in bone mass. We further tested the effect of Wnt7b on bone healing in a murine closed femur fracture model. Induced expression of Wnt7b at the onset of fracture did not affect the initial cartilage formation but promoted mineralization of the subsequent bone callus. Thus, targeted delivery of Wnt7b to aged bones or fracture sites may be explored as a potential therapy.

AMPK: implications in osteoarthritis and therapeutic targets.

Osteoarthritis (OA) is the most common skeletal disease and the leading cause of pain and disability in the aged population (>65 years). However, the underlying factors involved in OA pathogenesis remain elusive which has resulted in failure to identify disease-modifying OA drugs. Altered metabolism has been shown to be a prominent pathological change in OA. As a critical bioenergy sensor, AMP-activated protein kinase (AMPK) mediates not only energy homeostasis but also redox balance in chondrocytes to counter various cell stress. Dysfunction of AMPK activity has been associated with reduced autophagy, impaired mitochondrial function, excessive reactive oxygen species generation, and inflammation in joint tissue. These abnormalities ultimately trigger articular cartilage degeneration, synovial inflammation, and abnormal subchondral bone remodeling. This review focuses on recent findings describing the central role of AMPK in joint homeostasis and OA development. We also highlight current advances that target AMPK as a novel therapeutic strategy for OA prevention.

LncRNA-MALAT1 promotes osteogenic differentiation through regulating ATF4 by sponging miR-214: Implication of steroid-induced avascular necrosis of the femoral head.

OBJECTIVE: To study roles oflncRNA-MALAT1 and miR-214 in steroid-induced avascular necrosis of the femoral head (SANFH). METHODS: MALAT1, miR-214 andosteogenic-relatedgenes(Runx2, ALP, andOCN)expressions were determined in SANFH tissue samples and human bone marrow stromal cells (BMSC) by RT-qPCR. BMSCs were verifiedbyflowcytometry. The ATF4 level was determined by western blotting and RT-qPCR. Osteogenesis inducedbyosteogenic medium (OM) in BMSCs and dexamethasone (DEX) was used to inhibit osteogenesis. The alkaline phosphatase (ALP) activity was measured and ALP staining and alizarin red staining were conducted for evaluation of osteogenic differentiation. MTT assay was used for cell proliferation. The dual luciferase reporter assay was used to confirm binding between MALAT1 and miR-214, as well as miR-214 and ATF4. RESULTS: MALAT1 was down-regulated and miR-214 was up-regulated in SANFH tissues. DEX inhibited osteogenic differentiation of BMSC in a dose-dependent manner, leading to decreased MALAT1, increased miR-214, as well as reduced ALP activity and decreased expression of RUNX2, ALP and OCN. Either overexpression of MALAT1 or inhibition of miR-214 improved DEX-induced inhibition of BMSC osteogenic differentiation. The overexpression of miR-214 reversed the effects by MALAT1. MALAT1 directly sponged miR-214 and miR-214 directly targeted ATF4. CONCLUSION: MALAT1 was down-regulated, while miR-214 was elevated in SANFH tissues. MALAT1 promoted osteogenesis differentiation by sponging miR-214 to upregulate ATF4.

MicroRNA-29a suppresses the invasion and migration of osteosarcoma cells by regulating the SOCS1/NF-κB signalling pathway through negatively targeting DNMT3B.

The present study aimed to investigate the roles of the microRNA­29a/DNA methyltransferase 3B/suppressor of cytokine signalling 1 (miR­29a/DNMT3B/SOCS1) axis in the invasion and the migration of osteosarcoma (OS). The expression levels of miR­29a, DNMT3B and SOCS1 were determined in tissue samples and OS cell lines by reverse transcription­quantitative polymerase chain reaction (PCR). Apoptosis was measured using flow cytometry analysis. Transwell and wound healing assays were conducted to measure the invasion and migration abilities of OS cells, respectively. A dual­luciferase reporter assay was also conducted to determine the interaction between DNMT3B and miR­29a, while methylation­specific PCR was used to detect the methylation of SOCS1. Western blotting was performed to determine the protein levels of DNMT3B and SOCS1, as well as the levels of proteins associated with epithelial­mesenchymal transition (EMT), apoptosis and the nuclear factor (NF)­κB signalling pathway. The results demonstrated that miR­29a and SOCS1 were downregulated, and DNMT3B was upregulated in both OS tissues and cell lines. The expression of miR­29a and SOCS1 was found to be associated with advanced clinical stage and distant metastasis. In addition, the dual­luciferase reporter assay revealed that DNMT3B was a direct target of miR­29a. Overexpression using miR­29a mimics decreased DNMT3B expression and the methylation level of SOCS1, which resulted in the upregulation of SOCS1 in U2OS and MG­63 cells, while miR­29a inhibition led to the opposite results. Transfection with miR­29a mimics also promoted the apoptosis, and inhibited the invasion, migration and EMT process of OS cells, while it markedly reduced the nuclear translocation of p65 and IκB­α degradation. Treatment with 5­aza­2'­deoxycytidine worked together with miR­29a mimics to synergistically enhance the aforementioned effects. By contrast, the effects induced by miR­29a were partly reversed upon co­transfection with SOCS1 siRNA. In conclusion, miR­29a promoted the apoptosis, and inhibited the invasion, migration and EMT process of OS cells via inhibition of the SOCS1/NF­κB signalling pathway by directly targeting DNMT3B.

MAT1 facilitates the lung metastasis of osteosarcoma through upregulation of AKT1 expression.

AIMS: We aimed to elucidate the effects and mechanisms of MAT1 in the progression of osteosarcoma, especially for its lung metastasis. MAIN METHODS: CCK-8 and flow cytometry assays were carried out to detect the proliferation and apoptosis of osteosarcoma cells. Wound healing and transwell assays were used to determine cell migration and invasion abilities. Real time quantitative PCR (RT-PCR) and western blot technologies were applied to detect the expression levels of RNA and protein, respectively. KEY FINDS: The results showed that both the mRNA and protein expression levels of MAT1 were elevated in osteosarcoma tissues with lung metastasis and metastatic lung tissues, particularly in the metastatic lung tissues, as compared to the osteosarcoma tissues without lung metastasis. High expression level of MAT1 in osteosarcoma patients showed a negative association with the overall survival. In addition, upregulation of MAT1 induced significant increases in cell growth, migration and invasion and an obvious inhibition in cell apoptosis in osteosarcoma MG63 and 143B cells, as well as elevated AKT1 expression level. Moreover, knockdown of AKT1 obviously impaired MAT1-mediated promotions in cell migration and invasion in vitro, as well as repressed tumor growth and reduced the number of metastatic lung tumors in xenografted nude mice. SIGNIFICANCE: This study reveals that high expression of MAT1 closely related to the poor prognosis and malignant clinical process of osteosarcoma patients. MAT1 serves as a promoter in the lung metastasis of osteosarcoma through increasing AKT1 expression. Our study may provide a potent therapeutic target for the lung metastasis of osteosarcoma.