A smoldering global debate over human cloning is likely to flare following a report this week that researchers in South Korea have for the first time cloned human embryos and used them to produce a type of cell widely regraded as a potential key to treating a range of diseases.
These cells, known as embryonic stem cells, give rise to all the major cell types in the human body. Many biomedical researchers believe that they might be able to harness these cells - cloned from a patient's own DNA - to grow replacement organs or tissue that the patient's body will not reject.
Yet even as scientists remind the world that they still have a long way to go before embryonic-stem-cell therapies prove possible and perhaps become a reality, some acknowledge that advances could lead in another, more controversial direction: As other research teams improve on the Korean team's approach, it is possible that the world might see its first cloned humans before it sees its first approved therapies from embryonic stem cells.
The vast majority of researchers repudiate such "reproductive cloning," yet at least two fertility doctors - one in the US, the other in Italy - have claimed to have attempted cloning humans.
And although many researchers and biotech policy analysts are encouraged by the results, others hold that the work only reinforces the need for a ban on human cloning - whether for biomedical research or as a means of human reproduction.
"Reports of human cloning experiments undertaken in South Korea underscore the need for a comprehensive national and international ban on all human cloning," argues Sen. Sam Brownback (R) of Kansas, who has been one of the leaders of efforts in Congress to ban all forms of human cloning.
The team tapped 16 female volunteers, who were given treatments to induce them to produce an unusually large number of eggs. The researchers then removed the DNA from the 242 eggs and fused the eggs with other DNA-bearing "cumulus" cells from the volunteers. The end result - 30 blastocysts (early embryos with hundreds of cells), 20 that produced stem cells, and one colony of stem cells that the researchers built up in a petri dish.
Taken on their face, the new results are very significant, says Michael Werner, chief of policy for the Biotechnology Industry Organization (BIO) in Washington. "Theory suggested it would work. Now they've shown it can work."
When combined with what science has shown about stem cells' therapeutic potential using lab animals, he continues, the prospects for using stem-cell therapies appear to be brightening.
But at the same time, BIO president Carl Feldbaum says White House restrictions on stem-cell research and efforts in Congress to ban all forms of cloning have led to an uncertain climate for research in the US. "It's no coincidence that much of the groundbreaking work in this field is being done overseas."
Indeed, this fear that the vaunted US biomedical research enterprise could lose out to overseas competitors in a potentially lucrative arena forms one of the subtexts for the national and international debates over bans on human cloning.
Already, countries in Europe and Asia that have fewer political or religious objections to working with human embryos for therapeutic purposes are trying to forge ahead of the US in this field.
The prospect that someone, somewhere, will try to clone human beings has led to efforts at the UN to ban reproductive cloning in humans. But the effort has stalled over whether the ban should cover all forms of human cloning. The UN is slated to try again this September.