Embryonic stem lines unstable

Human embryonic stem cells accrue changes in their genomes that could make them unusable therapeutically when cultured at length, an international team of scientists report in the October Nature Genetics.
"Some of the early embryonic stem cell passages were relatively aberration-free, at least using the technology we have access to, even at passage 30 or so, which would be unusual for most adult stem cells," coauthor Anirban Maitra of Johns Hopkins University School of Medicine in Baltimore told The Scientist. Still, "over time, it appears that the majority of even embryonic stem cells do accumulate genetic and epigenetic changes."