Abstract: To examine the ability of plasmid DNA encoding the human mucins 1(MUC1) to elicit antigen-specific CTL responses by gene transfer mediated by dextran coated magnetic iron oxide nanoparticles (DMN） as gene carrier in vitro. METHODS： Dextran coated magnetic iron oxide nanoparticles (DMN） modified with Poly-L-Lysine (PLL） as gene carrier transfected plasmid pEGFP-C1-MUC1 as the reporter gene into human dendritic cells (HDC） in the magnetic field using Nd-Fe-B permanent magnet in vitro, and the rate of plasmid pEGFP-C1-MUC1 transfection into human dendritic cells were evaluated under fluorescence microscope，using RT-PCR and flow cytometer 24 h later. The transfected and nontransfected DC were then cocultured with autologous T cells , and with targeted bladder cancer cells (BIU87） seven days later. The cytotoxic activity or apoptosis of induced CTL to BIU87 was detected with LDH release assay or transmission electron microscope respectively. The IFN－γ secretion of the CTL was measured by ELISA assay. RESULTS： DMN acted as a vector in the magnetic field to transfect reporter gene pEGFP-C1-MUC1 into HDC. GFP was successfully expressed 24 h after transfection，and the rate of plasmid pEGFP-C1-MUC1 transfection was 10%. MUC1 expression was also detected as mRNA level in pEGFP-C1-MUC1 transfected DC. The transfected DC (DC-MUC1） successfully induced CTL with autologous T cells cocultured for seven days. The cytotoxic activity of induced CTL to BIU87 by T-DC-MUC1 was obviously higher than that by T-DC-pEGFP-C1 or T-DC. Transmission electron microscope showed apoptosis in the earlier period of CTL to BIU87 induction, for instance，disappearance of the nucleus、chromatin enriched around nuclear membrane, etc. There was significant difference in the ability of IFN－γ secretion between the transfected and nontransfected DC groups. CONCLUSION： Super-paramagnetic dextran coated magnetic iron oxide nanoparticles (DMN） as a vector could transfect plasmid pEGFP-C1-MUC1 into HDC MUC1 protein could enhance the ability of DC to stimulate autologous T cells proliferation and induce most potent cytotoxicity of CTL to bladder cancer cells(BIU87）.

Key words: MUC1 gene, bladder cancer, human dendritic cells immunological effect, dextran coated magnetic iron oxide nanoparticles, human dendritic cells, gene carrier .