Researchers in Oregon claim to have solved the tricky problem of cloning human stem cells, but you're more likely to see a duplicate of a years-old ethics debate than you are a duplicate human. 

The breakthrough is one that's been long sought after by biologists: creating perfectly matched human tissues through the process of cell cloning. In the past, researchers have had success with cloning animals through a technique known as somatic-cell nuclear transfer (SCNT), where the nucleus of an unfertilized egg is replaced with the DNA of a donor cell. (That's how Dolly the sheep was born.) The egg can then be turned into an embryo, with DNA that matches the original donor exactly. Later, stem cells from that developing embryo could be harvested and, in theory, be cultured to become almost any type of human cell there is. That would open a huge array of new medical treatments, from curing diabetes to fixing spinal cord injuries to providing rejection-proof organ transplants.

In the last decade or so, doctors had mostly turned away from SCNT as a means of producing "patient-specific" embryonic stem cells. They did so for a variety of reasons, but the biggest was that it didn't really work on humans. Researchers in South Korea claimed to have done just that in 2004, but their finding turned out to be a fake. Other attempts created imperfect results or were too expensive or inefficient. As a result, scientists have focused on other methods of attempting to create patient-specific stem cells. The focus now is on "reprogramming" adult cells so they become stem cells again, which has had limited success. (The new cells are called pluripotent cells, or iPS cells.) As one surprised researcher put it, "the most surprising thing [about this paper] is that somebody is still doing human [SCNT] in the era of iPS cells."

This new study will certainly revive interest in the procedure, but it will also revive the concerns that many people have with the entire messy business.

Unfortunately, there are still two huge issues with the process that have bogged down previous advances in endless debate. One is the ethical concern about human cloning. Once the embryo is created it could (again, in theory) be implanted in a uterus and develop in another human that is an exact genetic copy of the donors. Which is great for science fiction writers, but that's something a lot of people hope they never see. The researchers claim their technique does not allow for full human cloning (though they won't yet reveal how), but there's always the possibility that once the hurdle of cloning embryos is cleared, someone will find a way. There have been many calls in the past to ban the practice of human cloning before it can ever come to pass.

Second, and of more immediate concern for our world, is that the process of harvesting the stem cells requires the destruction of the embryo. (You also need to buy a lot of eggs from women willing to donate them.) To those who believe life begins at conception, that's tantamount to murder. That's why President George W. Bush banned the federal government from funding any new stem cell research that travels down that path, which is another reason why SCNT research has mostly fallen by the wayside in this century. (President Obama did relax many of those rules in 2009, but they've been caught up in legal battles for most of his presidency.)

However, this new development could spark renewed interest in that line of research and possibly a call to lift the ban. That won't sit well with those fighting to protect those embryos from destruction, which in turn will anger proponents of the research who believe it has the potential to save far more lives than it prevents. The new study also claims to destroy far fewer embryos than past techniques have, and work faster than other methods for creating stem cells.

Scientist have spent several years trying to come up with a new way to create stem cells that both works well with human cells and doesn't involve the destruction of embryos. If the Oregon researchers have solved one of those problems, but not the other—and as always, there's a lot more research needed to prove that it will work on a regular basis—it will be hard for others not to continue down the path they've laid out. If that happens, it will be harder still for the public, the scientific community, and our government to avoid having the same debates that weren't settled a decade ago.