A hepatic stem cell vaccine is superior to an embryonic stem cell vaccine in the prophylaxis and treatment of murine hepatocarcinoma

Stem cells and cancer cells express a common subset of antigens called oncofetal antigens. Theoretically, vaccination with stem cells is effective at boosting the preexisting anticancer immune response. Herein we describe the efficacy of two stem cell-based vaccines in the prophylaxis and treatment of subcutaneous hepatic tumors transplanted into mice. C57BL/6j mice were vaccinated weekly with either hepatic stem cells (HSCs) or embryonic stem cells (ESCs) for three weeks, followed by a subcutaneous challenge with Hepa 1-6 cells at one week (group 1) or four weeks (group 2) after vaccination. No tumor formation was observed in HSC-vaccinated mice when challenged within one week after vaccination (group 1), but tumors formed in 10% of mice in the ESC-vaccinated group and in 60% of mice in the unvaccinated group. When the long-term memory response was examined (group 2), only 10% of HSC-vaccinated mice and 20% of ESC-vaccinated mice developed macroscopic hepatocarcinomas compared to 60% of the unvaccinated mice. Besides their function as prophylactic vaccines, administration of either HSC or ESC could be a potential treatment for cancer. In mice with subcutaneous hepatocarcinomas, complete clearance of tumor burden was observed in 80% of mice receiving HSC vaccination, but 40% of ESC-vaccinated mice presented with tumors that did not increase in size over time. These data support that HSC is a superior vaccine candidate for durable antitumor protection in this hepatocarcinoma model.