[Progress on prevention and treatment of heterotopic ossification].

Heterotopic ossification is the formation of pathological bone in non-skeletal tissues (including muscles, tendons or other soft tissues), and the pathogenesis is not completely clear. It is often caused by musculoskeletal trauma, postoperative bone and joint surgery, or damage of the nervous system, the clinical manifestations are joint swelling, pain, and movement disorders, which often occur around the hips, knees, and elbows. At present, the prevention of heterotopic ossification mainly includes drugs, radiotherapy, molecular biological mechanism intervention, and Chinese medicine-related measures. Among them, drugs and radiotherapy are more effective methods to prevent heterotopic ossification. The intervention of molecular biology mechanism to prevent heterotopic ossification has become a new research direction and focus of attention inrecent years, and is basically at the experimental research stage. The treatment of heterotopic ossification includes various methods such as drugs, physical therapy, and surgery. Among them, surgery is recognized as the most effective treatment, however there are still some controversies and disagreements about the choice of operation time and surgical methods.

Local influence of high molecular polyethylene particles on heterotopic ossification.

We studied the effect of molecular polyethylene particles on local heterotopic ossification. A total of 36 healthy Sprague-Dawley rats were randomly divided into the control group (n=18) and the observation group (n=18). High molecular polyethylene particles were injected to rupture Achilles tendon position in the observation group, and normal saline was injected in the control group. X-ray examinations were conducted on Achilles tendon in the 4th, 8th and 12th week after operation. The incidence rate of heterotopic ossification was evaluated, and bone trabecula morphological structure was studied under optical microscope after hematoxylin and eosin staining. Bone morphogenetic protein 2 (BMP-2), transforming growth factor-ß (TGF-ß), interleukin-1 (IL-1), tumor necrosis factor-α (TNF-α), runt-related transcription factor 2 (Runx2) and matrix metalloproteinase-9 (MMP-9) expression levels were also measured. Our results showed that heterotopic ossification incidence in the observation group was significantly lower than that in the control group. Achilles tendon structure in the control group increased in volume, and its texture was harder and cartilage-like. In the observation group, trabecular bone volume, thickness and quantity were more than those observed in the control group. BMP-2, TGF-ß, IL-1, TNF-α, Runx2 and MMP-9 levels in the observation group were significantly lower than those in the control group. We concluded that, high molecular polyethylene particles had a significant inhibiting effect on local heterotopic ossification.

Mechanisms underlying the antiapoptotic and anti-inflammatory effects of monotropein in hydrogen peroxide-treated osteoblasts.

Monotropein, the primary iridoid glycoside isolated from Morindacitrifolia, has been previously reported to possess potent antioxidant and antiosteoporotic properties. However, there is no direct evidence correlating the antiosteoporotic effect of monotropein with its observed antioxidant capacity, and the molecular mechanisms involved in mediating these processes remain unclear. Therefore, the aim of the present study was to investigate the protective effects of monotropein against oxidative stress in osteoblasts and the mechanisms involved in mediating this process. Osteoblast viability was evaluated using the MTT assay. The mitochondrial membrane potential and reactive oxygen species were detected by flow cytometry analyses. Western blotting and enzyme­linked immunosorbent assays were performed to detect protein expression levels. A significant reduction in osteoblast viability was observed at 24 h following exposure to various concentrations (100­1,000 µM) of H2O2 compared with untreated osteoblasts. The cytotoxic effect of H2O2 was notably reversed when osteoblasts were pretreated with 1­10 µg/ml monotropein. Pretreatment with 1-10 µg/ml monotropein increased the mitochondrial membrane potential and reduced the generation of reactive oxygen species in osteoblasts following exposure to H2O2. In addition, the H2O2­induced increase in apoptotic markers (caspase-3 and caspase-9) and H2O2-induced reduction in sirtuin 1 levels were significantly reversed following pretreatment of cells with monotropein. Furthermore, monotropein significantly reduced H2O2­induced stimulation of NF­κB expression, in addition to the expression of a number of proinflammatory mediators. These results indicate that monotropein suppresses apoptosis and the inflammatory response in H2O2­induced osteoblasts through the activation of the mitochondrial apoptotic signaling pathway and inhibition of the NF­κB signaling pathway.

Curculigoside regulates proliferation, differentiation, and pro-inflammatory cytokines levels in dexamethasone-induced rat calvarial osteoblasts.

BACKGROUND: Curculigoside (CCG), one of the main bioactive phenolic compounds isolated from the rhizome of Curculigo orchioides Gaertn., is reported to prevent bone loss in ovariectomized rats. However, the underlying molecular mechanisms are largely unknown. Therefore, we investigated the effects of CCG on proliferation and differentiation of calvarial osteoblasts and discussed the related mechanisms. MATERIALS AND METHODS: Osteoblasts were incubated with dexamethasone (DEX) in the absence or presence of CCG concentrations for 24-72 h. Cell proliferation was evaluated by Cell Counting Kit-8 assay. Mitochondria membrane potential (MMP) and reactive oxygen species (ROS) were assessed by flow cytometry. We assessed the anti-inflammatory responses of CCG on DEX-induced osteoblasts by an enzyme-linked immunosorbent assay (ELISA). Relative protein expression of BMP-2, b-catenin, RANKL, OPG and RANK was measured using Western blotting. RESULTS: It was found that osteoblasts proliferation decreased significantly after treated with 1 µM of dexamethasone (DEX), compared with untreated osteoblasts and the cytotoxic effect of DEX was reversed remarkably when pretreatment with 25-100 µg/ml of CCG. Pretreatment with 25-100 µg/ml of CCG increased MMP level and decreased ROS production in osteoblasts induced by DEX. In addition, DEX-induced inhibition of differentiation markers such as alkaline phosphatase (ALP), OPG, BMP-2, ß-catenin, IGF-1 and M-CSF level, and promotion of differentiation markers such as RANKL and RANK was significantly reversed in the presence of CCG. CCG also reversed DEX-induced production of pro-inflammatory cytokines. CONCLUSIONS: These results provide new insights into the osteoblast-protective mechanisms of CCG through inducing proliferation and differentiation and reducing the inflammatory responses, indicating that CCG may be developed as an agent for the prevention and treatment of osteoporosis.