72 Therapeutic Cloning THERAPEUTIC CLONING And so in 1999, my colleagues and I proposed a controver- sial solution. We argued that the procedure called cell nuclear transfer – the transfer of a somatic cell into an enucleated egg cell – not only could produce embryos that when transferred into a uterus could produce a clone, but could also be har- nessed to make embryonic stem cells as well. [5] Such cells would be essentially identical to the patient’s cells. This could potentially solve the remaining problem of histocompatibil- ity  by  creating  human  embryonic  stem  cells  and  then  any cell in the body, all of which should never be rejected by the patient. The use of somatic cell nuclear transfer for the purposes of reversing time’s arrow on a patient’s cells has been designated therapeutic cloning. This terminology is used to differentiate this clinical indication from the use of nuclear transfer for the cloning of a child, which in turn is often designated reproduc- tive cloning. Since the debate over therapeutic cloning began, the power of the technique has become increasingly impressive. In April 2000, my colleagues and I reported evidence that the egg cell could act as a “cellular time machine”, not only reversing the arrow on differentiation (that is, not only converting a body cell like a skin cell into an embryonic stem cell), but also doing the unimaginable, returning the aged body cell to immortality and rewinding the clock of cellular aging as well. [6] These results, now reported for multiple mammalian species, sug- gest that we may have the potential to reverse the aging of human cells in the same manner. This would mean that we could make young cells of any kind for a patient of any age. While this “time machine” is expected only to be big enough to take on a single cell, the resulting  regenerated  cells  could  theoretically  be  expanded