Therapy of peritoneally disseminated colon cancer by TAP-deficient embryonic stem cell-derived macrophages in allogeneic recipients.

We established a method to generate a large quantity of myeloid lineage cells from mouse embryonic stem (ES) cells, termed ES cell-derived proliferating myeloid cell lines (ES-ML). ES-ML continuously proliferated in the presence of M-CSF and GM-CSF. ES-ML genetically modified to express an anti-HER2 (neu) mAb single-chain V region fragment reduced the number of cocultured mouse Colon-26 cancer cells expressing HER2. Stimulation of ES-ML with IFN-γ plus LPS or TNF resulted in almost complete killing of the Colon-26 cells by the ES-ML, and the cytotoxicity was mediated, in part, by NO produced by ES-ML. When ES-ML were injected into mice with i.p. established Colon-26 tumors, they efficiently infiltrated the tumor tissues. Injection of ES-ML with rIFN-γ and LPS inhibited cancer progression in the mouse peritoneal cavity. Coinjection of TNF-transfected or untransfected ES-ML with rIFN-γ inhibited cancer growth and resulted in prolonged survival of the treated mice. In this experiment, transporter associated with Ag processing (TAP)1-deficient ES-ML exhibited therapeutic activity in MHC-mismatched allogeneic recipient mice. Despite the proliferative capacity of ES-ML, malignancy never developed from the transferred ES-ML in the recipient mice. In summary, TAP-deficient ES-ML with anticancer properties exhibited a therapeutic effect in allogeneic recipients, suggesting the possible use of TAP-deficient human-induced pluripotent stem cell-derived proliferating myeloid cell lines in cancer therapy.

Application of iPS cell-derived macrophages to cancer therapy.

We established a method to produce a large quantity of myeloid cells from human inducible pluripotent stem cells (iPSCs). When injected intraperitoneally into mice carrying established peritoneal tumors, iPSC-derived myeloid cells (iPS-MCs) efficiently accumulated within neoplastic lesions. The intraperitoneal injection of iPS-MCs expressing interferon ß significantly inhibited the growth of human gastric and pancreatic cancers implanted in the peritoneal cavity of immunocompromised mice.

Therapeutic effect of human iPS-cell-derived myeloid cells expressing IFN-ß against peritoneally disseminated cancer in xenograft models.

We recently developed a method to generate myeloid cells with proliferation capacity from human iPS cells. iPS-ML (iPS-cell-derived myeloid/macrophage line), generated by introducing proliferation and anti-senescence factors into iPS-cell-derived myeloid cells, grew continuously in an M-CSF-dependent manner. A large number of cells exhibiting macrophage-like properties can be readily obtained by using this technology. In the current study, we evaluated the possible application of iPS-ML in anti-cancer therapy. We established a model of peritoneally disseminated gastric cancer by intraperitoneally injecting NUGC-4 human gastric cancer cells into SCID mice. When iPS-ML were injected intraperitoneally into the mice with pre-established peritoneal NUGC-4 tumors, iPS-ML massively accumulated and infiltrated into the tumor tissues. iPS-ML expressing IFN-ß (iPS-ML/IFN-ß) significantly inhibited the intra-peritoneal growth of NUGC-4 cancer. Furthermore, iPS-ML/IFN-ß also inhibited the growth of human pancreatic cancer MIAPaCa-2 in a similar model. iPS-ML are therefore a promising treatment agent for peritoneally disseminated cancers, for which no standard treatment is currently available.