Immunization with Embryonic Stem Cells/Induced Pluripotent Stem Cells Induces Effective Immunity against Ovarian Tumor-Initiating Cells in Mice

Figure 4

Self-renewal ability and tumorigenicity of CD133-positive ID8 cells. (a) ID8 cells formed floating tumor spheres about 50 μm in diameter after 12 days of culture in serum-free medium. CD133-negative and CD133-positive ID8 cells were dissociated into single-cell suspensions, and 500 cells per well were incubated in ultralow attachment 24-well plates. (b) FACS analysis of CD133 expression in ID8 cell line, spheroid-derived cells, and transplanted tumor-derived cells. (c) 10⁴ CD133-positive and CD133-negative cells were inoculated in 6-cm collagen-coated dishes in DMEM medium containing 5% FBS for 7 days. The colonies derived from CD133-positive cells are fully fuzed, whereas the colonies derived from CD133-negative cells are isolated and scattered. (d) CD133-positive cells generated spheroids more efficiently and larger than CD133-negative cells ( , , and , Student’s t-test). (e) As few as 100 CD133-positive ID8 cells were sufficient to form tumors, while equal numbers of CD133-negative cells failed to generate tumors in NOD/SCID mice. (f) NOD/SCID mice were transplanted with varying numbers (100, 500, 2,000, and 10,000 cells) of CD133-positive ID8 cells. As few as 100 CD133-positive ID8 cells were able to consistently develop tumor xenografts. (g) H&E staining revealed that adenocarcinomas generated from CD133-positive cells in NOD/SCID mice show a high density of tumor cells and poor differentiation compared to tumors resulting from unsorted cells, which consisted mainly of nonproliferative hyalinized differentiation (bar, 50 μm).

(a)

(b)

(c)

(d)

(e)

(f)

(g)