Objective To investigate the stimulation of exosome derived from osteosarcoma cells suppressing cytotoxic T cells and the inhibitory effect of active T cells for surpressing osteosarcoma cells. Methods Exosome derived from tumor cells was isolated and purified by ultracentrifugation. Its morphology was observed with transmission electron microscope, and the major histocompatibility complex-I ( MHC-I) molecules were analyzed by western blot. Mice bone marrow-derived dendritic cells were pulsed with exosome. Surface membrane MHC-I molecules were analyzed with flow cytometry. The effect of active T cells on the growth of osteosarcoma cells were detected by MTT assay after the T cells being stimulated by exosome-pulsed dendritic cells. Results The exosome was round or near round corpuscle, and the diameter was about 50-100 nm by transmission electron microscope. The size was relatively homogeneous. Western blot showed that the exosome expressed MHC-Ⅰmolecules. Surface membrane CD80,MHC-I and II molecules were expressed on 77. 16%, 83. 21%, and 91. 26% of LPS-treated dendritic cells, respectively, which were up-regulated compared to untreated cells. Dendritic cells pulsed with exosome derived from osteosarcoma cells caused significantly higher T cells stimulation and osteosarcoma cells inhibition as compared to un-pulsed dendritic cells. (P<0.05). Conclusion T cells can inhibit the growth of osteosarcoma cells after being stimulated by exosome-pulsed dendritic cells in vitro.

Objective To investigate the surgical techniques and clinical effects of anterior retropharyngeal approach in treatment of C2/3 fracture and dislocation.Methods Twelve patients with C2/3 fracture and dislocation treated via anterior retropharyngeal approach between November 2011 and April 2013 were included in the study.There were 7 males and 5 females aged from 19 to 65 years (mean,35 years).Primary pathologies included 7 patients with traumatic C3 fracture,2 with Hangman fracture and 3 with fracture and dislocation of the anteroinferior margin of C2 vertebrae.C2-C4 vertebrae were exposed using anterior retropharyngeal approach,followed by C2/3 discectomy or C3 corpectomy,decompression,interbody cage fusion or titanium mesh cage fusion,and anterior internal fixation.Results Exposure of lesion was sufficient for all patients and all operations were completed under direct vision,with mean operation time of 140 minutes and mean blood loss of 120 ml.One patient with reduced tone after operation gradually recovered in a week; one with dysphagia after operation recovered in 3 months; one with skin necrosis 7 days after operation was recovered by changing dressing; for the rest,there were no complications of incision hematoma,infection,or asphyxia.Ten patients were followed up for mean 15 months,which showed bony fusion in mean 6 months.At final follow-up,no implant loosening or displacement occurred.Conclusion Anterior retropharyngeal approach to C2/3 fracture and dislocation provides sufficient exposure of lesions,minor trauma,and less bleedings and complications,but as the local anatomy is complicated,there indeed exists a learning curve of the approach.

Objective: Dendrobium polysaccharide(DOP-1-1) was prepared and its effects on the proliferation, differentiation and mineralization of pre-osteoblast MC3 T3-E1 cells were investigated. Methods : A homogeneous polysaccharide(DOP-1-1) was obtained from Dendrobium officinale polysaccharide(DOP) through systematic separation and purification, and the structure of DOP-1-1 was studied by high-performance gel permeation chromatography, monosaccharide analysis, infrared spectroscopy, methylation analysis, GC-MS and NMR spectroscopy.In vitroexperiments were performed to detect the effects of DOP-1-1 on the proliferation, differentiation and mineralization of MC3 T3-E1 cells by MTT method, ALP activity determination and Alizarin Red S staining. At the same time, Western blot was used to determine the effect of DOP-1-1 on the expression of bone-related proteins(Pin1, BMP2, RUNX2) in MC3 T3-E1 cells. Results : DOP-1-1 was a homogeneous polysaccharide with relative molecular weights of 3 611, which was composed of mannose, glucose and galactose. DOP-1-1 had excellent activity of promoting osteoblast proliferation in a low concentration, and the effects of 2.0 and 4.0 μmol/L of DOP-1-1 were equivalent to Positive Control 17β-estradiol(E2). Compared with the control group, E2 and DOP-1-1(4.0, 8.0 μmol/L) increased the ALP activity and mineralization rate in MC3 T3-E1 cells(P<0.01). In particular, the ALP activity and mineralization rate of DOP-1-1(8.0 μmol/L) were higher than those of the positive control E2(P<0.001). In addition, the expression of Pin1, BMP2, and RUNX2 protein in MC3 T3-E1 cells in the DOP-1-1 group was higher than that in the control group(P<0.05). Conclusion DOP-1-1 can promote the proliferation, differentiation and mineralization of MC3 T3-E1 cells in vitro, and its mechanism is related to the activation of Pin1/BMP2 signaling pathway.