Human embryonic stem cells (ES cells) are of scientific and medical interest because of their ability to develop into different tissue types and because of their ability to be propagated for many generations in laboratory culture. Grown in a laboratory, they might one day be used in the treatment of degenerative diseases such as Parkinson’s and Alzheimer’s. They could provide bone cells for the treatment of osteoporosis, eye cells for macular degeneration, blood cells for cancer, insulinproducing cells for diabetes, heart muscle cells for heart disease, nerve cells for spinal cord injury. The potential for benefit to so many people is a strong argument for doing—and funding—embryonic stem cell (ESC) research. Yet ESC research is very controversial because the derivation of ES cells—at least at the present time—destroys the embryo. Thus, the morality of ESC research depends primarily on the morality of destroying human embryos, raising the question of the moral status of the human embryo.
The Oxford Handbook of Bioethics, edited by Bonnie Steinbock, Oxford University Press, 2007: 416-440