Figure 3.

Teratoma formation assay of NIS-expressing human induced pluripotent stem cell (iPSC) lines and NIS non-expressing human iPSC lines. (A) Three cell lines per group were injected subcutaneously into the back in immunodeficient mice. Mice injected with NIS non-expressing human iPSC lines showed obvious mass formation after 6 weeks (surrounded by a black dashed line). In contrast, mice injected with NIS-expressing human iPSC lines showed no visible mass formation from the external surface. (B) Teratoma formation was confirmed histologically in NSG mice injected with NIS-expressing and NIS non-expressing human iPSC lines. Scale bars are 200 µm. (C) NIS-expressing human iPSCs were injected into the right side of the back and NIS non-expressing human iPSCs into the left side of the back in immunodeficient rats. Six weeks later, ^99mTcO₄⁻ SPECT/CT was performed to detect NIS-expressing human iPSC-derived cells. NIS-expressing human iPSC-derived cells formed a smaller mass than NIS non-expressing iPSC-derived cells (surrounded by a white dashed line). (D) NIS-expressing human cells were confirmed histologically in immunodeficient rats. Scale bars are 50 µm.