Regarding the interview with Aubrey de Grey. Recently I read Jonathan Weiner's book (published 2010) "Long for this World: the Strange Science of Immortality", which consists largely of an extended interview over many years with Aubrey de Grey.
I can't really recommend it (Weiner's book "the Beak of the Finch" was much better from a science accuracy point of view). It's good in parts though.
I suspect the main reason why we age is because our mitochondria accumulate mutations in the 63 mitochondrial genes still present in the mitochondria, so eventually the mitochondria stop working and the cell dies. The damage results from free radicals produced during oxidative metabolism, and the only way of avoiding it is not to use the mitochondria at all (germ cells and stem cells apparently largely do this, which is why they are immortal).
This was discussed in Nick Lane's book "Power, Sex, Suicide: Mitochondria and the Meaning of Life".
de Grey's "solution" to this problem; transferring the remainder of the mitochondrial genes to the nucleus, even if feasible, wouldn't actually work; the genetic code in mitochondria is subtly different to that of the cell it is contained within.
Even if it were possible to engineer a perfect complement of mitochondrial genes to be present in the cellular nucleus, it begs the question as to why it hadn't previously occurred anyway, why the mitochondria still need to retain some very small fraction of its genes.
Nick Lane surmises that it allows the cell nucleus to produce just the right amount of mitochondrial protein for all the mitochondria present. If the mitochondria produce 13 of its oxidative enzyme complex components in the "right" amount, then it only needs to "grab" the remainder from the cytoplasm, which would be under negative feedback. Having a mitochondrion signal the nucleus that it "needs" (a positive feedback loop) more mitochondrial protein runs the risk that it will be swamped by all the other "sated" mitochondria in the cell.
