US scientists said they have successfully reprogrammed human skin cells to behave exactly as embryonic stem cells. The research was published in the Feb. 11 edition of the journal Proceedings of the National Academy of the Sciences. This is the third such confirmation that the technique is feasible.

"Our reprogrammed human skin cells were virtually indistinguishable from human embryonic stem cells," lead author Kathrin Plath, an assistant professor of biological chemistry at UCLA and a researcher with the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, said in statement.

"Our findings are an important step towards manipulating differentiated human cells to generate an unlimited supply of patient specific pluripotent stem cells. We are very excited about the potential implications."

Nuclear reprogramming creates stem-like cells from the patient's own cells, avoiding both medical and ethical problems. Two other research teams in Japan and the US said they were also able to successfully "rewind" adult cells back to their embryonic state in November last year using the nuclear reprogramming technique. However, it will take many years for the process to be deemed safe for actual use of the resulting stem cells in humans.

"Reprogramming normal human cells into cells with identical properties to those in embryonic stem cells without SCNT may have important therapeutic ramifications and provide us with another valuable method to develop human stem cell lines," said Lowry, an assistant professor of molecular, cell and developmental biology at UCLA and first author of the study.

The two research groups managed last year to obtain stem cells without the ethical problems posed by destroying human embryos. Through different techniques, they managed to turn human skin cells into cvasi-stem cells which appear to be pluripotent, having theoretically the ability to develop into any cell type.

Both experiments essentially replaced four genes in adult cells to make them behave like they were still embryonic stem cells. The two teams used viruses to force these genes into the cells' DNA and reprogram them. These results which used human tissue are a big step up from similar breakthroughs in mice, separately reported last summer by Dr. Yamanaka's group and two other research teams in the U.S.

Dolly's cloner also endorsed this technique and declared last year he abandoned human cloning in favor of nuclear reprogramming.

While "therapeutic" cloning produces stem cells, the technology involves the creation and destruction of embryos, which is ethically unsound. The stem cells created also run the high risk of being rejected by the recipient's body. In turn, nuclear reprogramming, creates stem-like cells from the patient's own cells, avoiding both medical and ethical problems.

Meanwhile, Geron said it applied for a license with the Food and Drug Administration to perform experiments using human embryonic stem cells in human subjects. The tests, if approved, would involve up to 40 human patients. This is the first time that a human embryonic stem cell application is being submitted to the FDA, the company said.