@cazzie Nikipedia gave a good scientific answer on an old Q of mine:
Let me speak a little bit more about the science behind this.
Inducing pluripotency in cells does not produce pluripotent cells that are identical to the ones derived from embryonic stem cells. It’s kind of like the difference between a heart and a pacemaker: they’re capable of performing the same function, but they’re not the same thing. And we don’t know all the ways these cells are different (yet).
The first time pluripotent cells were created, scientists took skin cells and used retroviruses to manipulate four genes to get them to return to a state of pluripotency. Unfortunately, one of the genes they manipulated was one that is often used to make normal cells into cancer cells. So if you tried to use these induced pluripotent cells, they would very often cause cancer. Not such a great side-effect, huh?
Since that initial breakthrough, scientists have been working to find a way to get around this problem by using recombinent proteins and by using adenoviruses. The adenoviruses appear to be able to circumvent the cancer problem, but are 1/100th as efficient as the other viral transfection agents. Also, this has only been accomplished in mouse cells, so far—no human cells have been returned to pluripotency using these methods (yet).
So the reasons scientists would still like to be able to use embryonic stem cells are because:
1. They are better. They are the real deal. They don’t have side-effects like causing cancer, or other side-effects that we don’t even know about yet that could impact the outcome of studies that use induced pluripotent cells.
2. They are cheaper. Scientists have to pay for this kind of research by asking the government and private companies for money. If you can’t raise enough money, you can’t do your experiments. (And this is not about scientists getting rich—they don’t get to keep the leftover money.)
3. They are more efficient. If you are using Technique A, and your buddy down the hall uses Technique B which is 100x faster, guess which one of you is going to be the first to use these cells to cure a disease?
So to answer the initial question: I am unequivocally in favor of using discarded embryonic stem cells for research as I see no ethical issues with it whatsoever, and as such I have no ethical problems with using any treatments that may eventually be derived from research using them.