Scientists in the United States have recovered human stem cells from cloned human embryos, in what is a world first. They have described it as a "significant step forward" in medicine.
Scientists have been trying to obtain stem cells from cloned human embryos for more than a decade, without success. It's understood that in previous attempts, the embryos stopped developing before producing the cells.
Stem cells are able to turn into any cell of the body, and scientists have long held an interest in using them to create transplant tissue for treating conditions like Parkinson's disease, multiple sclerosis, spinal cord injuries and blindness. But since transplants run the risk of rejection, scientists instead decided to create tissue that used the patient's own DNA through cloning.
The technique, described in the journal Cell by researchers from Oregon State University, involves transplanting an individual's DNA into an egg which itself has been stripped of all genetic material.
"A thorough examination of the stem cells derived through this technique demonstrated their ability to convert just like normal embryonic stem cells, into several different types, including nerve cells, liver cells and heart cells," said Shoukhrat Mitalipov, senior scientist at the Oregon National Primate Research Center.
Mitalipov said that because the reprogrammed cells use the patient's genetic material, there was no concern about transplant rejection.
The technique, a variation of a method called somatic cell nuclear transfer, was used to produce Dolly the cloned sheep in 1996. Dolly was the first mammal to be cloned.
"While there is much work to be done in developing safe and effective stem cell treatments, we believe this is a significant step forward in developing the cells that could be used in regenerative medicine," Mitalipov said.
He added that human cells in the study appeared even more fragile than those of monkey cells having undergone the same technique, which has so far not successfully produced any monkey clones.
This means it is unlikely the method could be used to create human clones, said Mitalipov.
"While nuclear transfer breakthroughs often lead to a public discussion about the ethics of human cloning, this is not our focus, nor do we believe our findings might be used by others to advance the possibility of human reproductive cloning," he said.
jr/msh (AFP, AP, Reuters)