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Embryo Stem Cells Genetically Unstable after Long Cultivation

Discovery may end hopes of using embryo stem cells directly in therapeutic applications

BALTIMORE, September 6, 2005 (LifeSiteNews.com) - Human embryonic stem cells have long been known to be unstable and difficult to control. In some cases, where they have been used directly in therapeutic trials, the use of embryo stem cells has been disastrous for patients. Now a researcher from Johns Hopkins University, an institution that has backed the use of embryos for research, has found that embryonic stem cells that are cultured in the lab accumulate genetic changes that may be linked to cancer.

Like a genetic game of “telephone” the longer the cells are cultivated, the more the genetic errors grow. Says Dr. Aravinda Chakravarti a geneticist at the Institute of Genetic Medicine of Johns Hopkins University in a report in the journal Nature Genetics, “These mutations we are finding are a much bigger problem.”

Chakravarti’s research team found that as they were cultured, stem cell lines went through 35 cell divisions and found that 90% showed changes in patterns of methylation – the process in which certain genes in a cell are turned on or off – 22% had mutations in mitochondrial DNA and 50% had major deletions or amplifications in the DNA. Moreover, it was the connection between the particular genetic problems the cells developed and the formation of tumours that was most worrying.

“[I]f it turns out these cells really do become unstable over time,” Chakravarti said, “then that would put limits on the practical life spans of the cells and their usefulness for therapeutic purposes.”

Chakravarti told the New Scientist that a possible solution would be to use the cells only when they are new and before extensive cultivation and division. However, the use of embryonic stem cells for disease treatment depends upon a long process of cultivation and differentiation into particular tissue types. Chakravarti’s discovery may end any lingering hopes of using embryo stem cells directly in therapeutic applications.

This discovery of the degradation of the genome of cultured stem cells comes at the same time a member of the UK’s House of Lords has decried the hype surrounding embryonic stem cells. The news media and certain factions in the scientific community have long promised that the use of cells derived from embryos and aborted foetuses will cure diseases, usually naming Parkinson’s, Alzheimer’s and diabetes. Meanwhile all the news regarding real cures and treatments for these and other serious diseases from adult stem cells goes largely unreported.

Speaking on the eve of this year's British Association Festival of Science, saying that the business of science is not certainty but uncertainty, one of the UK’s leading fertility experts and a supporter of embryo research, Lord Robert Winston said, “I think we need to be considerably more modest about our science. We do tend to hype up so many activities. The latest one in biology is the issue of embryonic stem cells. I view the current wave of optimism about embryonic stem cells with growing suspicion.”

Lord Winston pointed out, at nearly the same moment as the discovery at Johns Hopkins, that one of the biggest problems with embryonic stem cells was that “cultured stem cells are inherently unstable. When grown in the laboratory, they often produced cells with chromosomal abnormalities.”

Read New Scientist coverage:
http://www.newscientist.com/article.ns?id=dn7950

Read Lord Winston’s comments in The Scotsman:
http://thescotsman.scotsman.com/index.cfm?id=1890422005

Read related LifeSiteNews.com coverage:
http://www.lifesitenews.com/ldn/2003/sep/03091103.html

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