The process of removing stem cells from an embryo causes the embryo to die. This inevitable result is the cause of much controversy. The question of at what point is a fetus considered a living being is the central issue surrounding the research taking place. Pro-life advocates define the procedure as an act of murder, stating life begins at the moment of conception. This controversy has had a considerable impact on further developments within the field. As such, adult stem cell research efforts are looking into ways to simulate the differentiating process of embryonic cells.
Also at issue is the inherent potential to clone humans once a full understanding of the process is reached. This concern became particularly apparent when the first successful cloning of a lamb was done in 1997. Proponents of stem cell research continue to stress the treatment benefits that will accompany further progress made within the field. To date, current federal legislations prohibit further embryonic experimentation.