The cells were cultured, the defective gene causing the deficiency was replaced, and the children were then treated successfully with their own stem cells. We can expect that these same adult stem cells are present in humans. Thus, adult stem cells are already fulfilling the promises only dreamed of for ES cells. It is mysterious, if not maddening, then, that many scientists, patient advocacy groups, and bioethicists continue to press for unfettered access to embryonic cells. But in fact there are a number of other motivations in play.
Many scientists chafe at having to engage in ethical debates when such fascinating horizons beckon.
Equally alluring, however dim, is the vision of a fountain of youth. The process by which human cells age is poorly understood, but some suspect that embryos might offer clues for making adult cells young again. Lurking behind the es cell debate are some uncomfortable realities about the extent to which Americans already deploy medical technology that, intentionally or inadvertently, leads to the destruction of the most vulnerable members of the human species. Whatever the reasons, the ethical and political questions that have arisen from the debate over ES cells will only increase as our science moves ahead. This time, we will not be engineering machines, but engineering ourselves.