Induction of anti-tumor immunity in mice using a syngeneic endothelial cell vaccine.

Tumor endothelium could represent a novel target for active and passive immunotherapies of cancer. Here, we show that endothelial cells can be used as a vaccine in mice. In this study, three endothelial cell vaccine preparations from syngeneic (SVR), allogeneic (ISOS-1) and xenogeneic (ISO-HAS) sources were used to vaccinate mice. All mice developed humoral immune responses to endothelial cells and showed lower basal serum VEGF levels (37-45% lower) compared with unvaccinated control mice. Mice receiving the syngeneic SVR vaccine showed substantial inhibition of tumor growth after B16F10 melanoma challenge (50% of the mice in this group were tumor-free). The tumors that developed in the few mice in the syngeneic group had lower microvessel density counts (4-5 fold) compared with the other groups. The data suggests an in vivo antiangiogenic effect as the potential mechanism for the anti-cancer effect. In summary, further studies using other tumor models to demonstrate broad protection of this novel type of antiangiogenic vaccine are warranted.