“…The three unstable ESC lines (ORMES-1, -2, and -5) showed, even at low passages, structural abnormalities, such as translocations (t(11;16) and t(5;19) with der (18) t(1;18)), or invertions (inv (1)). It has been hypothesized that the collagenase-based dissociation technique, used for ORMES-1, -2, and -5, may have contributed to the onset of karyotypic abnormalities in these cell lines (Mitalipov et al, 2006). Mouse Unexpectedly, an accurate literature search showed that only a few papers described the genomic variation of mESCs during a long period of culture.…”