Korean researcher Woo Suk Hwang claimed in 2004 to have created a human embryonic stem cell line using a technique called somatic cell nuclear transfer (SCNT). Over the following two years, his results were discredited. This year, however, a report from researchers at Children’s Hospital Boston and the Harvard Stem Cell Institute revealed that Hwang was indeed a pioneer—albeit by unwittingly exploiting an altogether different approach to creating embryonic stem cells.
To create an embryonic stem cell line using SCNT, a biologist sucks out the nucleus of an egg cell and replaces it with the nucleus of another cell—ideally one taken from the patient in need—creating a patient-specific stem cell line. Ongoing attempts to create human stem cell lines using SCNT have yet to achieve success.
Another process, called parthenogenesis, could yield stem cell lines that are genetically matched to a patient—in this case, the egg donor. In parthenogenesis, an egg is prodded to develop into an embryo without fertilization. Human parthenogenetic embryos are not viable—they run into developmental snags and cannot give rise to a person—but the stem cells derived from these embryos could still have research or therapeutic value.
Hwang claimed his stem cells did not result from parthenogenesis, but George Daley, head of the study, showed that the genome of Hwang’s cell line has a genetic signature that indicates it sprang from a parthenogenetic embryo.
Since 2004, several groups have reported creating stem cell lines through parthenogenesis. But Daley says his study shows “with very, very high certainty that the first Hwang line was in fact also the world’s first parthenogenetic line.”
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