July 7 - CiRA researchers working in collaboration with Hideyuki Okano's group at Keio University have published a breakthrough study with potentially important medical implications. Using induced pluripotent stem (iPS) cells shown in previous work to be non-tumorigenic, the team injected mice with damaged spinal cords and assessed both stem cell activity and functional recovery. They found that not only were the iPS-derived neurospheres capable of differentiating into neuronal, astrocyte, and oligodendrocyte lineages in vivo, they contributed to re-myelination and the recovery of locomotor function as well, all without any evidence of tumor formation. Reported in the online edition of the Proceedings of the National Academy of Sciences, these findings represent a preclinical breakthrough in the use of iPS cells in the treatment of neuronal defects. In addition to the tremendous importance of the functional recovery, the team of Keio and CiRA researchers showed for the first time how a "safe," non-tumorigenic clone of iPS cells could be isolated from a larger colony and, through in vivo experiments, how these behave differently from their seemingly similar non-safe brethren, which give rise to teratomas.