Osteocytic cells exposed to titanium particles increase sclerostin expression and inhibit osteoblastic cell differentiation mostly via direct cell-to-cell contact.

The mechanism underlying induction of periprosthetic osteolysis by wear particles remains unclear. In this study, cultured MLO-Y4 osteocytic cells were exposed to different concentrations of titanium (Ti) particles. The results showed that Ti particles increased expression of the osteocytic marker SOST/sclerostin in a dose-dependent manner, accelerated apoptosis of MLO-Y4 cells, increased the expression of IL-6, TNF-α and connexin 43. SOST silence alleviated the increase of MLO-Y4 cells apoptosis, decreased the expression of IL-6, TNF-α and connexin 43 caused by Ti particles. The different co-culture systems of MLO-Y4 cells with MC3T3-E1 osteoblastic cells were further used to observe the effects of osteocytic cells' changes induced by Ti particles on osteoblastic cells. MLO-Y4 cells treated with Ti particles inhibited dramatically differentiation of MC3T3-E1 cells mostly through direct cell-to-cell contact. SOST silence attenuated the inhibition effects of Ti-induced MLO-Y4 on MC3T3-E1 osteoblastic differentiation, which ALP level and mineralization of MC3T3-E1 cells increased and the expression of ALP, OCN and Runx2 increased compared to the Ti-treated group. Taken together, Ti particles had negative effects on MLO-Y4 cells and the impact of Ti particles on osteocytic cells was extensive, which may further inhibit osteoblastic differentiation mostly through intercellular contact directly. SOST/sclerostin plays an important role in the process of mutual cell interaction. These findings may help to understand the effect of osteocytes in wear particle-induced osteolysis.

Reduction of SOST gene promotes bone formation through the Wnt/ß-catenin signalling pathway and compensates particle-induced osteolysis.

The increase in bone resorption and/or the inhibition of bone regeneration caused by wear particles are the main causes of periprosthetic osteolysis. The SOST gene and Sclerostin, a protein synthesized by the SOST gene, are the characteristic marker of osteocytes and regulate bone formation and resorption. We aimed to verify whether the SOST gene was involved in osteolysis induced by titanium (Ti) particles and to investigate the effects of SOST reduction on osteolysis. The results showed osteolysis on the skull surface with an increase of sclerostin levels after treated with Ti particles. Similarly, sclerostin expression in MLO-Y4 osteocytes increased when treated with Ti particles in vitro. After reduction of SOST, local bone mineral density and bone volume increased, while number of lytic pores on the skull surface decreased and the erodibility of the skull surface was compensated. Histological analyses revealed that SOST reduction increased significantly alkaline phosphatase- (ALP) and osterix-positive expression on the skull surface which promoted bone formation. ALP activity and mineralization of MC3T3-E1 cells also increased in vitro when SOST was silenced, even if treated with Ti particles. In addition, Ti particles decreased ß-catenin expression with an increase in sclerostin levels, in vivo and in vitro. Inversely, reduction of SOST expression increased ß-catenin expression. In summary, our results suggested that reduction of SOST gene can activate the Wnt/ß-catenin signalling pathway, promoting bone formation and compensated for bone loss induced by Ti particles. Thus, this study provided new perspectives in understanding the mechanisms of periprosthetic osteolysis.

Excessive swelling of nerve roots : Important factor for recurring sciatica after lumbar surgery.

OBJECTIVE: The aim of the study was to investigate the occurrence of unexpectedly swollen nerve roots and to investigate the relationship between nerve root edema and recurrent radicular pain. METHODS: During the period from August 2010 to August 2015, a total of 462 patients with degenerative lumbar disease underwent surgery in this study group. Magnetic resonance imaging (MRI) was used to evaluate the details of the nerve root. Of the patients with recurring radiating pain 13 met the inclusion criteria of the study group and 24 patients without any complications volunteered as the control group. The visual analog scale (VAS), Oswestry Disability Index (ODI), and medical outcomes study item short form health survey (SF-36) were used to evaluate the clinical outcomes. RESULTS: The preoperative diameter of the nerve root showed no significant difference between the two groups (P = 0.28). The postoperative nerve diameter of the study group was larger than that of the control group (P < 0.01). The initial operation improved the symptoms and the VAS was significantly decreased (P < 0.01). After recurrence of the neuralgia, the VAS score significantly increased (P < 0.01). The pain of the study group improved to the same level as that of the control group 4 weeks after subsequent surgery (P = 0.47), while the quality of life was still lower than that of the control group (P < 0.05). The scores collected 3 months after surgery showed that the clinical outcomes were not different between the two groups (P > 0.05). CONCLUSION: In surgery for degenerative lumbar disease accompanied by nerve root edema, excessive nerve root swelling is an important factor for recurrent radiating pain. With a properly carried out intervention in the re-exploration, the recurrent symptoms can be gradually relieved.

MicroRNA-221 regulates osteosarcoma cell proliferation, apoptosis, migration, and invasion by targeting CDKN1B/p27.

MicroRNAs (miRNAs, miR) are of critical importance in growth and metastasis of cancer cells; however, the underlying functions of miRNAs in osteosarcoma (OS) remain largely unknown. This study was aimed to elucidate the role of miR-221 in regulating the biological behavior of OS cells. The proliferation ability was examined by cell counting kit-8 (CCK-8) and cell cycle assay. The abilities of cell migration, invasion, and apoptosis were monitored by transwell assay and flow cytometry, respectively. The effect of miR-221 on cyclin-dependent kinase inhibitor 1B (CDKN1B) expression was evaluated by luciferase assays, real-time polymerase chain reaction, and Western blot analysis. We found that miR-221 was elevated in OS cell lines compared with the normal osteoblastic cell line. Transfection of the miR-221 inhibitor into MG63 and U-2OS cell lines obviously suppressed cell proliferation, migration, and invasion, which is accompanied with cell cycle arrest in G0/G1 phase. Furthermore, luciferase reporter assays indicated that CDKN1B is directly targeted by miR-221 in OS cells. Knockdown of CDKN1B inhibited the effects of miR-221 inhibitor, along with decreased Bax and caspase-3 and increased cyclin E, cyclin D1, Bcl-2, Snail, and Twist1 expression. The results suggested that miR-221 might act as a potentially useful target for treatment of OS.

Sinomenine increases osteogenesis in mice with ovariectomy-induced bone loss by modulating autophagy.

BACKGROUND: A decreased autophagic capacity of bone marrow mesenchymal stromal cells (BMSCs) has been suggested to be an important cause of decreased osteogenic differentiation. A pharmacological increase in autophagy of BMSCs is a potential therapeutic option to increase osteoblast viability and ameliorate osteoporosis. AIM: To explore the effects of sinomenine (SIN) on the osteogenic differentiation of BMSCs and the underlying mechanisms. METHODS: For in vitro experiments, BMSCs were extracted from sham-treated mice and ovariectomized mice, and the levels of autophagy markers and osteogenic differentiation were examined after treatment with the appropriate concentrations of SIN and the autophagy inhibitor 3-methyladenine. In vivo, the therapeutic effect of SIN was verified by establishing an ovariectomy-induced mouse model and by morphological and histological assays of the mouse femur. RESULTS: SIN reduced the levels of AKT and mammalian target of the rapamycin (mTOR) phosphorylation in the phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR signaling pathway, inhibited mTOR activity, and increased autophagy ability of BMSCs, thereby promoting the osteogenic differentiation of BMSCs and effectively alleviating bone loss in ovariectomized mice in vivo. CONCLUSION: The Chinese medicine SIN has potential for the treatment of various types of osteoporosis, bone homeostasis disorders, and autophagy-related diseases.

Spinal extradural arachnoid cyst following percutaneous vertebroplasty.

We report a rare complication of extradural arachnoid cyst following percutaneous vertebroplasty in a spinal metastasis patient. Percutaneous vertebroplasty has been established as a safe and effective treatment for osteoporotic vertebral fractures and vertebral metastatic lesions. To our knowledge, extradural arachnoid cyst following vertebroplasty has not been reported in literature. A 48-year-old woman diagnosed with adenocarcinoma underwent percutaneous vertebroplasty at the L3 vertebral level due to painful solitary spinal metastasis. At 5 months after surgery, the patient complained of low back pain radiating to the left lower extremity. MRI showed a large cystic lesion in the spinal canal at the L2-L3 level with compression to adjacent dura sac. On T1- and T2-weighted images, the signal within the cyst had the same intensity as cerebrospinal fluid. The patient underwent laminectomy for excision of the extradural cyst. Intraoperatively, a small communication between the cyst and the subarachnoid space was seen at the level of the L3 pedicle. Pathological examination revealed that the cyst wall was composed of non-specific fibrous connective tissue and the content of the cyst was the same as that of cerebrospinal fluid. Postoperatively, the patient's symptom was relieved immediately. The iatrogenic dural injury produced by puncture of the pedicle during vertebroplasty may be the cause of formation of the extradural arachnoid cyst.

Treatment of femoral neck fracture with percutaneous compression plate: preliminary results in 74 patients.

OBJECTIVE: The purpose of this study was to present the surgical technique and clinical results of percutaneous compression plate (PCCP) for the treatment of femoral neck fractures. METHODS: Between December 2010 and April 2013, 74 consecutive patients with 74 femoral neck fractures were treated by closed reduction and PCCP implants in our university hospital. Their mean age was 51.3 years (range, 15-83 years); 38 (51.4%) were male and 46 (62.2%) of the fractures were on the left. The patients' clinical and radiographic data were analyzed retrospectively. RESULTS: There were 45 undisplaced (60.8%) and 29 displaced fractures (39.2%). Eight patients (10.8%) were lost to follow-up. The mean duration of follow-up was 18.8 months for the remaining 66 patients. At the last follow-up, mean Harris hip score was 92.9 (range, 75-100), and 65 patients (98.5%) had excellent and good outcomes. Sixty-five patients (98.5%) were able to walk independently and one (1.5%) with walking-sticks. The mean time to clinical fracture healing was 3.9 months. There were no cases of nonunion. Two patients (3.0%) had delayed union and two (3.0%) developed avascular necrosis, one of 29 (3.7%) with a displaced fracture and one of 45 (2.6%) with an undisplaced fracture. There were no other complications or prosthetic replacement. CONCLUSIONS: PCCP is a stable internal fixation device that resists axial and rotational stresses. Our PCCP procedure has a low incidence of nonunion and avascular necrosis.

Nogo-C contributes to HCC tumorigenesis via suppressing cell growth and its interactome analysis with comparative proteomics research.

OBJECTS: Neurite outgrowth inhibitor proteins (Nogos) comprise a family of three major members and are characterized by a conserved RHD domain. Among all the members, Nogo-B was identified to be significantly elevated and to play an important role in liver cirrhosis while Nogo-C was the shortest one and received little attention. The aim of this study is to investigate the relevance and mechanism of Nogo-C involved in Hepatocellular carcinoma (HCC). METHODS: The expression of Nogo-C in paired HCC specimens was measured with quantitative RT-PCR. The function of Nogo-C over expressing in SMMC-7721 and WRL-68 HCC cell lines were estimated through cell proliferation assay and colony formation assay. A proteome-wide identification of Nogo-C-binding proteins was performed using affinity purification combined with a highly sensitive mass spectrometric technique. The protein interactions were confirmed using co-IP and immunofluorescence confocal assays. RESULTS: Compared with the neighboring pathologically normal tissues, the expression of Nogo-C mRNA was extremely down-regulated in HCC specimens and was significantly related to greater tumor size and worse prognosis. Overexpression of Nogo-C in HCC cell lines resulted in an inhibition of cell growth. A total of 73 proteins were detected and considered in association with Nogo-C, among which B-raf and Nogo-B were validated. CONCLUSION: We identify Nogo-C as a tumor suppressor gene in HCC and B-raf as a novel interacting protein. These findings provide new directions for the mechanism research of Nogo family.

Cannabinoid receptor-2 selective antagonist negatively regulates receptor activator of nuclear factor kappa B ligand mediated osteoclastogenesis.

BACKGROUND: The cannabinoid receptor-2 (CB2) is important for bone remodeling. In this study, we investigated the effects of CB2 selective antagonist (AM630) on receptor activator of nuclear factor kappa B (RANK) ligand (RANKL) induced osteoclast differentiation and the underlying signaling pathway using a monocyte-macrophage cell line-RAW264.7. METHODS: RAW264.7 was cultured with RANKL for 6 days and then treated with AM630 for 24 hours. Mature osteoclasts were measured by tartrate-resistant acid phosphatase (TRAP) staining using a commercial kit. Total ribonucleic acid (RNA) was isolated and real-time reverse transcriptase-polymerase chain reaction (RT-PCR) was done to examine the expression of RANK, cathepsin K (CPK) and nuclear factor kappa B (NF-κB). The extracellular signal-regulated kinase (ERK), phosphorylation of ERK (P-ERK) and NF-κB production were tested by Western blotting. The effect of AM630 on RAW264.7 viability was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assay. RESULTS: AM630 did not affect the viability of RAW264.7. However, this CB2 selective antagonist markedly inhibited osteoclast formation and the inhibition rate was dose-dependent. The dose of ≥ 100 nmol/L could reduce TRAP positive cells to the levels that were significantly lower than the control. AM630 suppressed the expression of genes associated with osteoclast differentiation and activation, such as RANK and CPK. An analysis of a signaling pathway showed that AM630 inhibited the RANKL-induced activation of ERK, but not NF-κB. CONCLUSION: AM630 could inhibit the osteoclastogenesis from RAW264.7 induced with RANKL.

Kyphoplasty does not maintain all restored height postoperatively: a prospective, comparative study.

From January to December 2008, balloon kyphoplasty was performed on 45 consecutive female patients with primary single-segment vertebral compression fractures as an inpatient procedure. All of the treated vertebral bodies were located within the thora-columbar region (T11-L2). Demographic data such as age, body mass index, fracture age, hospital stay, lumbar spine bone mineral density, and amount of bone cement injected per vertebrae were recorded. Patients were analyzed clinically by ambulatory status and the visual analog scale (VAS) for pain. Lateral radiographs were used to measure changes in anterior vertebral height. Mean anterior vertebral height increased from 58.9%+/-12.50% pre-kyphoplasty to 79.8%+/-7.12% post-kyphoplasty (P<.001).Two groups were defined based on the percentage of height restoration achieved: group A (18 patients) with a height restoration of at least 20%, and group B (27 patients) with a height restoration of 0% to 19.99% post-kyphoplasty. Mean anterior vertebral height restored in groups A and B was 28.2%+/-7.2% and 12.1%+/-6.2%, respectively (P<.05). Four patients in group A and none in group B had height loss at the treated vertebral level (P<.05). Both VAS and ambulatory status were improved after treatment (P<.05) with no significant difference between the 2 groups. Kyphoplasty can restore the collapsed vertebral height, but patients with greater height restoration were more vulnerable to a loss of corrected height.