Effects of 10 μM PEITC-treated compared with untreated HeLa cells and hCSCs in a xenotransplant NOD/SCID mouse model. A) Representative photomicrographs of H&E-stained and sectioned tumors (3 μm, 400x) showing greater and more aggressive tumorigenic effects of hCSCs (iii) than HeLa cells (i). Details of native HeLa cells within a small tumor nodule with fairly uniform cell size and shape are shown (ii), and details of a small tumor nodule showing widespread apoptosis are also shown (iv). Empty arrows indicate apoptotic cells (yellow), high mitotic activity (blue), and early signs of neovascularization (white). B) Average tumor number per injection, where the untreated hCSC group showed the highest number of tumors per injection. C) The highest concentration of human serum VEGF-A was in the hCSC group, indicating the human origin of the tumors that were translocated into the blood circulation. D) The metastatic potential among the groups is shown. Metastasis was observed only in the untreated hCSC group. E) Representative photomicrographs of H&E-stained and sectioned lungs (3 μm, 200x). Filled arrows indicate lung bronchiole (yellow) as a landmark of distant tumor location and invading tumor cells (white) (iii). Overall, hCSCs showed increased tumorigenic activity compared with HeLa cells in this model, which was, however, attenuated upon pre-treatment with PEITC.