Stem cells cultured for long periods in the lab develop genetic changes in areas known to be involved in human cancers, researchers are warning.The potential therapeutic benefits of human embryonic stem cells, which so many researchers are pinning their hopes on, should perhaps come with a “best before date”, US-based researchers suggest. “It seems that there must be something in the cell culture that turns on some genetic pathways, which in the body would normally be modulated,” says Aravinda Chakravarti, who led the research at the Johns Hopkins University School of Medicine in Baltimore, US. “We don’t know why stem cells are so sensitive to mutations in vitro, or even if it is just stem cells that show such mutations over time, but certainly the medium in which they are cultured needs to be investigated,” he adds.
