It's considered a useful step in stem cell research.
"For the first time they took cells from living human beings and managed to make five-day-old embryos that were genetically identical to those living human beings," says Prof. Hank Greely with Stanford Law School.
In other words, the clone's DNA matches the donor's. The stem cells will now be harvested from the embryo, with the goal of one day turning those cells into replacements for damaged tissues in humans.
"These cloning techniques have been promoted as ways to provide personal repair kits -- patient specific therapies -- and that's highly unlikely," says Marcy Darnovsky with the Center for Genetics and Society.
Those at the Center for Genetics and Society support stem cell research, but it's the promise behind it and the manner in which this type of testing is done, that they oppose. Most often, it requires using women's eggs.
In the San Diego study, scientists asked women who were already donating their eggs for invetro fertilization, if they could have any extras. Then, they asked the couples who were actually paying the procedures if they could also have those eggs for free. Both parties agreed.
Critics question the ethics behind it, but no laws were broken.
"I'm not sure I see any ethical problem there. The women aren't enticed to do this by money for research; the parents chances of having a baby aren't diminished," says Prof. Greely.
Professor Greely specializes in laws surrounding bioscience. He says stem cell research will remain controversial as long as human eggs and embryos are used.
Recently, scientists in Japan found a way to reprogram skin cells to act like embryonic stem cells. While that method is still in its early stages, it could bring an end to the ongoing moral and ethical conflict, allowing the focus to shift back to science.