Anti-Tumor Activity of Mannose-CpG-Oligodeoxynucleotides-Conjugated and Hepatoma Lysate-Loaded Nanoliposomes for Targeting Dendritic Cells In Vivo

Dendritic cell (DC)-based tumor vaccines are a promising immunotherapeutic method of cancer treatment. However, their therapeutic applications are significantly limited by their weak immunogenicity, costly culturing steps, and easily degradable properties. Thus, the anti-tumor activity for the vaccines should be improved. In this study, a novel lipid nanoparticle (M/CpG-ODN-H22-Lipo) was developed, which was conjugated with synthetic CpG oligodeoxynucleotides (CpG-ODN) and mannose and then loaded with H22 hepatoma lysate. Our data corroborate that M/CpG-ODN-H22-Lipo selectively targeted DCs and significantly increased their induced-maturation. Besides, the vaccine halted tumor growth and extended survival of mice with hepatocellular carcinoma. Moreover, M/CpG-ODN-H22-Lipo treatment reduced the percentages of myeloid-derived suppressor cells (in the tumor and bone marrow) and regulatory T cells (Treg) in the spleen. In contrast, the number of IFN-gamma-positive cells in the spleen along with the serum IgG levels were up-regulated. Moreover, tumor angiogenesis and tumor-cell proliferation were halted by the treatment of M/CpG-ODN-H22-Lipo, whereas tumor cell apoptosis was up-regulated. Our data revealed that CD8(+) T cells and NK cells were vital to mediate the anti-tumor immunity of M/CpG-ODN-H22-Lipo treatment. In sum, the results here proved M/CpG-ODN-H22-Lipo vaccine a safe, specific and effective DC-based anti-tumor immunotherapy with great potential for clinical applications.