A report published online today that researchers have cloned human embryos is not that much of an advance, according to one stem cell expert, Douglas Melton, at Harvard University.

Researchers at Stemagen Corporation in La Jolla, Ca, reported that they cloned human embryos from adult oocytes using somatic cell nuclear transfer, according to a report published online today (January 17) in the journal Stem Cells.

Using eggs from adult women who had previously donated for successful fertility treatments, the researchers used SCNT to transfer DNA into the egg cells. Several of the reconstructed oocytes developed as normal embryos, although only one of the blastocysts contained donor DNA or mitochondrial DNA.

"It would be hard to call this a major advance," Douglas Melton, a stem cell researcher at Harvard University, told The Scientist in an Email. He cited the work of two other groups that have also successfully produced human embryos using SCNT. "Nothing new has been learned as far as I can tell."

The next step in this work would be to create a viable embryonic stem cell line, Melton added, something that still evades researchers.

The disgraced South Korean researcher, Woo Suk Hwang, claimed to have created such an embryonic stem cell line. His work was retracted in 2006.