Extraordinary opportunities to study and to treat human diseases are provided by the recently acquired ability to derive stem cells from human embryos. Because these cells form all of the tissues that make up an adult, they afford a chance to study normal human development in the laboratory, to define the abnormalities associated with inherited disease and, in time, perhaps to treat diseases, many of which have no effective treatment at present.
Consider just three situations among many. Cells derived from embryo cells could be used to repair spinal cord injury. It is far from clear exactly what type of cell should be used, how many cells are needed or where they should be placed. Nevertheless, speedy treatment might provide real benefit.
