Objective: To investigate the therapeutic potential of human embryonic stem cells (hESCs) as a vaccine toinduce an immune response and provide antitumor protection in a rat model. Methods: Cross-reactivity ofantigens between hESCs and tumour cells was screened by immunohistochemistry. Fischer 344 rats were dividedinto 7 groups, with 6 rats in each, immunized with: Group 1, hESC; Group 2, pre-inactivated mitotic NuTu-19;Group 3 PBS; Group 4, hESC; Group 5, pre-inactivated mitotic NuTu-19; Group 6, PBS; Group 7, hESC only.At 1 (Groups 1-3) or 4 weeks (Groups 4-6) after the last vaccination, each rat was challenged intraperitoneallywith NuTu-19. Tumor growth and animal survival were closely monitored. Rats immunized with H9 and NuTu-19 were tested by Western blot analysis of rat orbital venous blood for cytokines produced by Th1 and Th2 cells. Results: hESCs presented tumour antigens, markers, and genes related to tumour growth, metastasis, and signalpathway interactions. The vaccine administered to rats in Group 1 led to significant antitumor responses andenhanced tumor rejection in rats with intraperitoneal inoculation of NuTu-19 cells compared to control groups.In contrast, rats in Group 4 did not display any elevation of antitumour responses. Western blot analysis foundcross-reactivity among antibodies generated between H9 and NuTu-19. However, the cytokines did not showsignificant differences, and no side effects were detected. Conclusion: hESC-based vaccination is a promisingmodality for immunotherapy of ovarian cancer.
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