A first: Stem cell lines made from embryos of primates

— -- Scientists in Oregon have successfully cloned monkey embryos and used them to make two embryonic stem cell lines. It is the first time this has been accomplished in primates and brings the possibility of human stem cell lines one step closer to reality.

Researchers at Oregon Health and Science University in Portland removed the DNA from a rhesus macaque egg and replaced it with genetic material from a different macaque's skin cell. The two were fused with electricity. After five to seven days, this early-stage embryo was destroyed to harvest the stem cells.

This is the heart of the controversy over stem cell research, which researchers hope will provide cures for diabetes, Parkinson's and spinal cord injuries, among others. Embryonic stem cells are important because they can become almost any cell in the body. But the destruction of embryos to harvest those cells is vehemently opposed by right-to-life groups.

If this technology worked in humans, it would mean that a patient's skin cell could be implanted into a hollowed-out egg to make a cloned embryo that would produce personalized stem cells and transplant tissue.

The research is "a significant step" toward being able to create human stem cell lines, says Arnold Kriegstein, director of the Institute for Regeneration Medicine at the University of California at San Francisco.

The Oregon group, led by Shoukhrat Mitalipov, has no plans to move on to human research. "We only work with monkeys," says Mitalipov. "However, we hope the techniques we developed will be useful for other labs working on human subjects."

There's much work to be done, says Mitalipov. His group required 304 macaque eggs to produce only two stem cell lines, a success rate of just 0.7%.

"What's notable is that they found it so difficult," says Jonathan Moreno, a professor of medical ethics at the University of Pennsylvania. "That suggests we'll still have a lot of warning before there's a successful birth of a cloned human being."

That's good news to opponents of stem-cell research.