For the teratoma formation assay, 1×106 cells of each hiPSC line were dissociated with Accutase (Millipore), spun down, and resuspended in 100 µl of PBS. NOD-SCID mice were anesthetized by standard procedures, and the cell suspensions were injected into the right and left thigh muscles (1×106 cells per site) of three mice. The mice were monitored during recovery. Tumors were apparent by about 4 weeks. The tumors were collected, fixed, sectioned, and stained with hematoxylin-eosin to identify teratomas. The protocol was approved by the Animal Care and Use Committees of the Gladstone Institutes and the University of California, San Francisco.
