To assess the in vivo pluripotency of iPS cell lines, teratoma formation assays were performed16. iPS cells were injected subcutaneously into the dorsal flank of SCID mice. Animals were monitored and teratomas were dissected at 8 to 10 weeks post-injection. Tissues were fixed in 10% neutralized formalin solution (Sigma). Embedding, sectioning and haematoxylin and eosin staining were carried out by the Pathology Core Facility at the Johns Hopkins University Hospital.
