“Ten years ago, we talked about the potential of nuclear transfer for therapy. But it turns out the technique was of no practical relevance. You would never do it in humans for a number of reasons. First, it’s very inefficient. With mice, that doesn’t matter because we can do hundreds of transfers to get a few mice. But human cloning is another order of magnitude more difficult than in mice. And people can’t even get the eggs to practice [on]. My former student Kevin Eggan, along with his colleagues at Harvard, spent years putting in place a protocol to get volunteer egg donors. They spent a couple hundred thousand dollars just in advertising. And I think they got one or two donors. Kevin’s postdoc, Dieter Egli, who went to Columbia, told me that he got a couple [of] human nuclear transfers going, but they all arrested at the 6- or 8-cell stage.The Family Research Council's David Prentice provides some background information and his thoughts about Jaenisch's statement.