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.