Monkey embryo cloning has no immediate human application: researchers

A team of U.S.-led researchers say they have succeeded in cloning monkey embryos and extracting stem cells, but warn their findings won't have human health ramifications any time soon.

Embryonic stem cells are believed to have enormous health potential because they can be genetically matched to a patient and can reproduce tissue for different parts of the body.

The researchers, led by Shoukhrat Mitalipov at Oregon Health and Science University in Portland,reported thatthey had succeededin cloning embryos of the rhesus macaque monkey this week in the journal Nature.

Mitalipov's team merged skin cells of a nine-year-old rhesus macaque male with unfertilized monkey eggs that had their DNA removed. The eggs, now operating with DNA from the skin cells, grew into early embryos in the laboratory. Stem cells were recovered from these embryos.

Due to the 2004 fraudulent claim by South Korean researchers that they had cloned a human embryo, Nature had a second set of researchers verify the team'sfindings. The verification report in the journal, by Australian scientists, saidtheir result "demonstrates beyond any doubt" that the stem cells came from cloned embryos.

The only other animal in which cloned embryonic stem cells have been created is mice.

Despite the team's success in cloning and extraction, they said theirprocedures are not easily transferable to humans. The rate of success is still relatively low— the research team produced two embryonic stem cell extractions from 304 eggs. To try it in humans, researchers would require many unfertilized eggs.

Mitalipov said that if further research could reduce the "inefficient" process to maybe five to 10 eggs per stem cell batch, "we will be closer to clinical applications." He added, "I am quite sure it will work in humans."

Another difficulty in applying the research to human health is that human embryonic stem cell research faces political and ethical restrictions, because human embryos have to be destroyed to produce the stem cells.

Mitalipov said he plans to do diabetes studies in monkeys in an attempt to prove that stem cells can be used to treat diseases safely.