Scientists say they have created a stem cell line from a human embryo that had stopped developing naturally, and so was considered dead. Using such embryos might ease ethical concerns about creating such cells, they suggested. One expert said the technique makes harvesting stem cells no more ethically troublesome than organ donation. But others said it still carries scientific and ethical problems. Scientists want to use human embryonic stem cells to study diseases and create transplant tissue for treating illnesses such as diabetes and Parkinson's disease. Such cells are taken from human embryos that are a few days old, and the harvesting process destroys the embryo. That raises ethical objections.