( An international team of researchers ha...)Embryonic stem cells accrue genetic changes

The findings do not limit the utility of the cells for some types of research or for some future clinical applications, the researchers say, but draw attention to the need to closely monitor stem cell lines for genetic changes and to study how these alterations affect the cells' behavior. The researchers' work is described in the Sept. 4 online edition of Nature Genetics.

"This is just the first step," says Aravinda Chakravarti, Ph.D., one of the research team's leaders and professor and director of the McKusick-Nathans Institute of Genetic Medicine at Johns Hopkins. "While this is a snapshot of the genomic changes that can happen, it's certainly not everything going on. We still need comprehensive analyses of the changes and what they mean for the functions of embryonic stem cells."

"Embryonic stem cells are actually far more genetically stable than other stem cells, but our work shows that even they can accumulate potentially deleterious changes over time," adds Anirban Maitra, M.B.B.S., an assistant professor of pathology at Johns Hopkins who shares first authorship of the paper with Dan Arking, Ph.D., an instructor at Hopkins. Both are members of the McKusick-Nathans Institute of Genetic Medicine at Johns Hopkins. "Now it will be important to figure out why these changes occur, how they affect the cells' behavior and how time affects other human embryonic stem cell lines."

The researchers in the United States, Singapore, Canada and Sweden compared "early" and "late" batches of each of nine federally approved human embryonic stem cell lines. Twenty-nine human embryonic stem cell lines from seven different companies are approved by the United States National Institutes of Health under President George W. Bush's policy restricting federal funding of this research to cell lines in existenc
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Source:Johns Hopkins Medical Institutions