It's good to see that you've done research on this. First off, your description of nuclear transfer is a gross misrepresentation of the actually process if not misunderstanding. Let me lay out a historical perspective. In 2005, a Korean researcher claimed that he was able to reliably perform nuclear transfer and was heralded as the biggest breakthrough in ESC research of 21st century. And you probably know that it was shown to be a scientific fraud. That was 5 years ago, and still the whole field hasn't been able to figure out a way to do this. As I said taking a nucleus out of a single ESC and replace it with another is an extremely difficult process that is fundamentally challenging. Even if this will one day be possible, another challenge is when it's transplanted in human body, it will form teratoma. Teratoma is the fundamental requirement of ESC because that's what defines ESC and what confers its ability to regenerate. So if you want to use ESCs you need to differentiate it down a certain pathway so you know for sure that the ESC cannot form teratoma but still capable enough to regenerate the tissue of interest. This is again an extremely difficult process. So ESC in their native form has no value except for research. So why is then adult stem cell more promising? There is a spectrum of stem-cell-likeness. When you are a blastocyst you have unlimited potential of multiplication. When you are old you are not so much so. What IPS researchers have found is that the machineries that make cells stem cells are still there and can be turned on. Using this gives you huge advantages. These cells will never form teratoma. These cells will be immunocompatible as they are autologous. As far as regenerative capacity is concerned there's already clinical studies that have shown that adult stem cells can indeed regenerate certain tissues. For example, HSC have been used for a while to regenerate bone marrow after chemo for leukemia. MSCs have been used to regenerate other types of tissues. There are varying degress of success, but with IPS, this can only go up.