Fig. 5

Detection of tumorigenic cells in vitro and in vivo. a: Cell growth assay of each passage. b: Soft agar colony formation assay. Phase-contrast micrographs of MRC-5 cells, HeLa cells, HeLa cells spiked into MRC-5 cells, and hiPSCs-CMs cultured on soft agar medium for 21 d. Arrows indicate colonies. Scale bar: 200 μm. c, d: Tumorigenicity was evaluated through transplantation of hiPSC-CM patches with or without purification of cardiomyocytes and elimination of residual undifferentiated hiPSCs into the left ventricular surface of immunodeficient NOG mice. c Representative hematoxylin and eosin staining of teratomas. Scale bar: 1000 µm (left panel) and 2000 µm (right panel). d Quantification of the rate of teratoma formation (no treatment group: hiPSC-CM patches without purification of cardiomyocytes and elimination of residual undifferentiated hiPSCs, n = 10; treatment group: hiPSC-CM patches with purification of cardiomyocytes and elimination of residual undifferentiated hiPSCs, n = 10)