Does adult stem-cell research hold the same therapeutic promise?
The jury is still out. Depending on whom you ask, you will either be told adult stem cells have demonstrated a surprising ability to transform into other cell types and repair damaged tissue, or that such transformations are relatively rare and can sometimes be accounted for by alternative explanations. Embryonic stem cells are taken from three-to five-day-old embryos. These cells are exciting to researchers because at this stage, they have the potential to give rise to any cell type (muscle, bone, nerve, skin, etc.) in the body. On the other hand, it was initially thought that adult stem cells – which are found in many tissues (in children and adults), as well as umbilical cord blood and the placenta – could only produce progeny cells corresponding to their tissue of origin. For example, skin stem cells give rise to the various types of cells in the skin. However, many recent studies suggest that adult stem cells are able to generate cell types other than those in their tissue of orig