"No legitimate scientist would be stepping forward to apply this in reproductive cloning, or for fertility work," Daley said. "I would argue that really there are no good medical reasons to generate a cloned baby."
So what is it good for?
There's one important area where experts say Mitalipov's method could have tremendous implications: Mitochondrial disease.
The mitochondria are the "power plants" of cells, supplying them with chemical energy. DNA in the mitochondria is inherited entirely from the mother's egg, unlike the DNA in the cell's nucleus, which comes from both parents.
Mutations in mitochondrial DNA can lead to deadly diseases, and their associated mutations are passed down to each new generation. Induced pluripotent stem cells preserve these harmful mutations, says Mitalipov.
A cell's mitochondrial DNA develops mutations over the course of a lifetime, little by little, and may result in diseases such as Parkinson's disease and diabetes, Mitalipov said. It's possible, he says, that one day there will be stem cell treatments for aging and age-related diseases.
The only way to ensure that stem cells derived from an adult patient do not have mitochondrial DNA mutations would be to use the technique demonstrated in the new study, Mitalipov said: Creating embryos with cells from the patient's own body, and healthy eggs, for the purpose of deriving embryonic stem cells.
"You want 0 miles in (the) rejuvenated cells that you want to put back into these patients," he said. "The 0 mileage engine is in the egg."
Mitalipov's group also demonstrated in a 2012 Nature study that it could be possible to, using genetic techniques, reconstruct embryos that would not have the unhealthy mitochondrial mutations. This is not cloning, but draws on similar knowledge, and could cure a family's genetic disease lineage in the future.
Daley estimates human clinical trials in stem cells will start within one to three years, but perhaps it could take a decade or more before the impact of stem cell therapy becomes widespread.
Gearhart is confident that the more we learn how to manipulate stem cells safely, there will be safe way to provide them to patients who need them. But there are different levels of risk for different uses. There will always be a risk-benefit calculation to be made, he said.
Different areas of stem cell research have proven to be harder than others. Beta cells for type I diabetes have been "a very difficult nut to crack," Gearhart said, but there have been promising developments in repairing the heart, something that his lab has worked on, as well as for eye diseases.
"I think it's going to be exciting times over the next several years when it comes to this," he said.