S Korean stem cells derived from eggs alone-study

CHICAGO, Aug 3 (Reuters) An analysis of a now-discredited South Korean stem cell line suggests the scientists may have inadvertently created the first human embryonic stem cells derived from human eggs alone, US researchers said.

South Korean scientist Hwang Woo-suk falsely claimed to have been the first to clone a human embryo using a process called somatic cell nuclear transfer in scientific papers published in 2004 and 2005.

That work was discredited and the papers were withdrawn in a scandal that stunned scientists.

But researchers at the Harvard University Stem Cell Institute and Children's Hospital Boston Stem Cell Program believe the South Korean scientists unwittingly may have made a significant discovery.

''What is so interesting is they did by this by mistake,'' said Dr George Daley, whose analysis appears in the journal Cell Stem Cell. ''They didn't really know what they had.'' Using a new genetic sleuthing method derived by Daley and colleagues, he yesterday said they have determined that the South Korean cell line was derived from parthenogenesis, a type of asexual reproduction in which an egg develops into an embryo without sperm.

''If they had identified this as a parthenogenetic stem cell ... it would have been very exciting,'' he said in a telephone interview.

Stem cells are master cells of the body, and while they occur throughout all tissues and organs, they are hard to grow.

Embryonic stem cells can be made either from days-old embryos left over from fertility clinics or by cloning technology -- although no researchers have succeeded yet in cloning a human embryo.

Cloning -- also called somatic cell nuclear transfer -- is a process in which the nucleus of an egg is replaced by the nucleus from a cell in the body.

Parthenogenesis offers a third approach. The process involves chemically tricking an egg into developing without being fertilized by sperm.

Daley's team has done this in mice, and he said researchers recently succeeded in humans.

Daley and colleagues have now devised a set of standards to analyze the DNA of embryonic stem cells that allows researchers to determine how they were made.

They used this method to analyze the South Korean stem cell line. ''We now know that they are unequivocally human parthenogenetic stem cells,'' he said.

Scientists say embryonic stem cells might one day be used to create tailor-made medical treatments, and say studying them can help doctors better understand disease.

While parthenogenetic stem cells may not be as useful as those derived from cloned cells might, Daley said they would still be useful for research.

Human embryonic stem cell research is controversial. Opponents say destroying an embryo is tantamount to taking a human life.

Reuters KK GC0900