Scientists create stem cells from cloned human embryos

Scientists have derived colonies of embryonic stem cells from cloned human embryos for the first time. In experiments documented in an article from the journal Nature, scientists from the New York Stem Cell Foundation Laboratory say they have created two lines of the cells through the use of somatic cell nuclear transfer (SCNT), also known as cloning. Scientists hope the cells could one day be used to treat or even cure diseases like diabetes and bring about an era of so-called “regenerative medicine.”

Unlike normal stem cells, the cells obtained by the team also included DNA from the human eggs used in the process, resulting in a highly abnormal 69 chromosomes rather than the usual 46. That makes the cells useless for therapy, but, argued lead scientist Dieter Egli in a press conference with reporters, the cells can be used “to address important questions, like asking how these cells compare to [other stem-like cells]…We now have a reliable assay to build on to conduct future research.”

Larry Goldstein, director of the University of California San Diego Stem Cell Program, said the experiment is a significant accomplishment.

“It’s not going to lead to a therapy,” he said. “But from a longer term perspective, it is very important.” It will help tease out the reasons why human SCNT has been so difficult.

In 2008, a San Diego biotech, Stemagen, announced that it created human blastocysts by cloning. A company spokesman told that it has done it twice since, but efforts to derive long-lasting stem cells have failed.

This new experiment appears to elucidate the main problem. Unlike SCNT in other animals that have been cloned, the New York team demonstrated that certain factors in the human egg’s nuclear DNA are required to make resulting stem cells viable.

“When we first removed the [egg] genome and replaced it with the genome of the skin cell, development [of the embryo] arrested after a few divisions,” Egli said. So they left the egg’s DNA in place. That way, whatever gene products that make the difference between survival of embryos and stem cells, what those are haven’t been identified, would still be present.

Gerald Schatten, director of the Division of Developmental and Regenerative Medicine at the University of Pittsburgh School of Medicine predicted this nearly a decade ago. Based on past work of his own, he suggested that it might be necessary to leave an egg DNA structure called the meiotic spindle intact if the embryo was to develop and the resulting stem cells live. In light of this new paper, he wrote in an email, “it is reasonable to conclude that primate eggs (human and non-human alike) differ from mice and other rodents, and also eggs from domestic species” like cows and pigs.

With these new cell lines it should be possible to figure out what those differences are and navigate around them.



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