“… 21 , 22 It is worth mentioning that the problems that we had to face during the process of generation and characterization of the cells were numerous, especially regarding the adaptation to feeder-free conditions. There are currently a lot of published combinations of matrices and culture media to replace feeder layers (reviewed in Dakhore et al., 8 Sams and Powers, 8 , 11 , 13 , 20 , 23 , 24 , 25 Skottman and Hovatta, 8 , 11 , 13 , 20 , 23 , 24 , 25 Liu et al., 8 , 11 , 13 , 20 , 23 , 24 , 25 Anderson et al., 8 , 11 , 13 , 20 , 23 , 24 , 25 Nakamura et al., 8 , 11 , 13 , 20 , 23 , 24 , 25 Kishimoto et al. 8 , 11 , 13 , 20 , 23 , 24 , 25 ).…”