Last week the journal Nature reported that scientists in New York have created human embryo clones for the purpose of developing patient-specific stem cells. The process involves reprogramming a human egg via somatic cell nuclear transfer so that the egg becomes an early-stage human embryo. The hope is that, in the future, the patient’s own DNA will be used to produce the clone and, thus, he or she will have access to matching stem cells. Successful clones using animal eggs go back to the 1996 conception of Dolly, the cloned sheep. However, according to Nature, “When it came to humans, researchers didn’t have unfettered access to the key resource, eggs — at least not in the numbers that they needed to tweak the finicky procedure for human biology.” Of course, this “finicky procedure” entails the controversial procurement of human eggs from donors, the inevitable trial and error destruction of the newly created human embryos in order to produce a successful clone, and the eventual killing of the cloned embryo at the blastocyst stage in order to extract the desired stem cells.
For example, in the latest research, scientists obtained 270 eggs from 16 donors, in and of itself a risky procedure for the donors. The unique feature of this latest research is that researchers discovered that previous attempts at cloning failed because of the difficulty of removing DNA from the human egg. This time, they decided to leave the original DNA in the egg and simply added the donor’s DNA. This novel method resulted in the creation of an embryo with an additional set of chromosomes. The newly created embryo grew to the blastocyst stage which is, of course, the phase at which stem cells can be obtained. The problem for future research is that, with an additional set of chromosomes, the stem cells are no longer a match for the patient. Instead, we are left with an abnormal human embryo with too many chromosomes. Even so, scientists press on with their research because they doubt the success of iPSCs; cloning offers a “more natural” method of obtaining stem cells.
It seems almost comical to think that adding someone else’s DNA to an egg that already contains its own DNA is somehow a “more natural” process. Nonetheless, from my perspective, it seems that researchers are very quick to highlight the apparent problems with iPSCs, a technology that is still in its infancy, and yet downplay the obvious technical and ethical problems with hESCs.