Fig. 6

Prevention of a potential risk of USCs using YM155 in vitro and in vivo. Expression of pluripotent genes (NANOG and OCT4) was traced from days 6 to 15 with the group of 5 nM YM155 pretreated at stage II (a). For teratoma formation, QIA7 (stage 0) and QIA7-iHeps (stage II) were pretreated with or without YM155 for 24 h and approximately 1 × 10⁶ cells were injected into the right testis of all mouse (b). After 6–7 weeks, teratoma forming was estimated and compared among the groups (c, d). Testes indicated by numbers in (d) underwent histological analysis (e). Teratoma mass derived from QIA7 (① and ②) and QIA7-iHeps (④ and ⑤) without YM155 treatment showed tissues of three germlayers but testes injected with YM155-pretreated donor cells showed a typical testis structure(③ and ⑥). iHep induced hepatocyte, OCT4 octamer-binding transcription factor