Despite being hailed as a scientific breakthrough in treating debilitating diseases, transplants using fetal tissue remain a controversial area of research due to the tissue’s source—aborted fetuses. Embryonic stem cells from fetuses have the potential to grow into a variety of body parts and organs, including the heart, brain, and nervous system. Scientists hope that transplanting these fundamental stem cells will help regenerate diseased cells, offering an effective treatment and possible cure for such diseases as Parkinson’s and Alzheimer’s.

During the late 1980s and 1990s, many scientists focused their fetal tissue research on the treatment of Parkinson’s disease. Advocates of fetal tissue transplants have praised the results of clinical trials that injected fetal brain tissue deep into the deteriorating brains of Parkinson’s sufferers. They assert that, unlike...