The High Efficiency Of DC/Tumor Cell Hybrid Vaccine Anti-cancer Research

Surgery, radiotherapy, chemotherapy and immunotherapy are currently themain therapeutic approaches for the treatment of cancers. Among thesetherapeutic approaches, immunotherapy based on dendritic cells (DCs) has beena promising anti-tumor strategy and has been extensively studied. Studies on thereinfusion of DC/tumor cell hybrid vaccine have been conducted in clinic for thetreatment of human cancers. However, the efficiency of cells fusion and thestability of fusion cells are the key factors affecting the bioactivity of DC/tumorcell hybrid vaccine and the anti-tumor effectiveness. Polyethylene glycol (PEG)has been widely used for inducing cell fusion because of low cost and beingeasy to conduct. However, a number of disadvantages of PEG limit itsapplications in inducing DC/tumor fusion cells. For example, the fusion cellsrate ranges dramatically and in some cases it may be extremely low. In addition,the toxicity of PEG can reduce the activity and stability of DC/tumor cell hybridvaccine. Therefore, improving the cell fusion rate to increase the activity andstability of DC/tumor fusion cells is of great importance.Type I collagen (CI) can tightly crosslink phospholipid molecules to compete the cell surface tension, therefore to repair the damaged cell membrane.In addition, CI can also transduce cell signal and keep the integrity of cellmembrane by regulating the extracellular microenvironment homeostasis. In thisstudy, based on the biological characteristics of CI, we developed a novelmethod using a combination of CI to PEG to induce fusion of DC/tumor cells.This novel cell fusion approach may enhance the fusion rate and increase theactivity and stability of DC/tumor cell hybrid vaccine to further activate strongerT cells responses, which results in better anti-tumor effects. Our resultsdemonstrated that this novel fusion method based on the combination of PEGand CI significantly increased the cells fusion rate and the activity and stabilityof DC/tumor cell hybrid vaccine, and enhanced the activation of tumor-specificT cells. Our study provides an alternative for efficient generation of DC/tumorcell hybrid vaccine and this method may be powerful for the specific treatmentof cancers.Objective: To establish a novel method inducing efficient fusion of DCs andB16tumor cells based on the combination use of PEG and CI. To evaluate thecell fusion rate, the activity of fusion cells, and the anti-tumor effects of DC/B16cell hybrid vaccine in the treatment of melanoma.Methods: DCs and melanoma cells were induced by the combination of PEGand CI to generate DC/B16cell hybrid vaccine. Flow cytometry was used toanalyze the expression of a number of surface markers on DC/B16cell hybridvaccine. Cell proliferation assay was used to evaluate the T cell proliferationinduced by DC/B16cell hybrid vaccine and the serum level of IFN-γ secretedby T cells under the stimulation of DC/B16cell hybrid vaccine was measured byFlow cytometry. The ability of T cells to kill target cells was measured byPKH26staining. The in vivo anti-tumor effects of DC/B16cell hybrid vaccine were investigated in the melanoma model in mice.Results: Combination of PEG and CI induced the fusion of DCs and B16cellswith high frequency and stability. The fusion cells, PEG/CI-DC/B16, exhibitedhigh levels of expression of CD80, CD86, and MHC-II and strong abilityinducing the proliferation of T cells that secreted high level of IFN-γ and abilityof killing melanoma cells in mice. Subcutaneous injection of PEG/CI-DC/B16in melanoma mice efficiently inhibited the tumor growth and prolonged thesurvival of melanoma mice by decreasing the amount of CD4regulatory T cell(Treg) and MDSC cells, inhibiting the proliferation and promoting apoptosis oftumor cells.Conclusion: Combination of PEG and CI can increase the efficiency of fusionof DCs and melanoma B16cells and improve the stability and activity of fusioncells. Therefore, this novel fusion method can improve the anti-tumor effects ofT cells.