We have previously shown that hESCs can be maintained in a xeno-free environment and induced to differentiate into NSCs and subsequently to authentic dopaminergic neurons using animal origin-free components by a four-step scalable protocol [5]. To test whether iPSCs could be adapted to defined medium culture while retained genetic integrity and maintained the ability to generate multipotent NSCs after prolonged culture, we cultured and differentiated two human iPSC lines MMW2 and MR31 using identical components as for hESCs. The MMW2 line was derived from adult mesenchymal stem cells by the standard four retroviral vectors expressing the four factors, Oct4, Sox2, Klf4, and c-Myc [11]. The MR31 line was reprogrammed by only three factors (omitting c-myc) from human fetal fibroblasts [16]. Both lines were shown to be pluripotent and karyotypically normal [17].
