Objective To investigate the cell-fusion modes and contractive characteristics of myotubes formed by muscle satellite cells in vitro. Methods The muscle satellite cells in quadriceps femoris of six 2-day-old SD rats were isolated, cultured and identified by immunofluorescence; the cell-fusion modes and contractive characteristics of myotubes were observed and recorded under microscope. Results The positve cells expressing marker Pax7 were obtained by immunofluorescence, and the purity was 90.3%. Myotubes were fused by several cells, cell and myotube or myotube and myotube. There were myotubes of spontaneous contraction on the conditions of no acetylcholine, no electric stimulation or no contiguous cells. Conclusion The myotubes of spontaneous contraction are fused by muscle satellite cells through three cell-fusion modes in vitro.

Objective:To study the mechanisms of immune suppression mediated by Gr-1+CDllb+ myeloid derived suppressor cells (Gr-1~+CDllb~+MDSC)from tumor-bearing mice.Methods:Gr-1~+CDllb~+MDSC recruited into spleen and bone marrow of tumor-bearing mice were purified by Percoll,and suppression mediated by MDSC on T cell proliferation from spleen of naive mice was detected by flow cytometry with CSFE and FTTC-anti CD3 staining,and NO,ROS,IL-10 and TGF-β in the supematant of MDSC were detected by Griess and ELISA.Results:There were much more Gr-1~+CDllb~+MDSCs in spleen and bone marrow from tumor-bearing mouse than those of naive mouse,and suppression on T cell proliferation mediated by MDSC from tumor beating mouse was significantly increased,and there were much more NO,ROS,IL-10 and TGF-βin the supematant of these MDSC than that from naive mouse.Conclusion:MDSC from tumor-bearing mice secreted hish level of NO,ROS,IL-10 and TGF-βto induce immune suppression,and inhibite the proliferation of T cells.