eventually the diaphragm as well, which pulls and pushes air into the lungs. think about that. the brain is fine. but you simply cannot breathe. john knows there is no cure for als, and so does his wife, and his two daughters. >> my first thoughts were, i hated for my girls to see me go through this. >> reporter: so today is a historic day. what we're going to see is the first fda-approved clinical trial for fetal stem cells in adults. it's remarkable. obviously, a lot of issues here. dr. feldman developed the trial. >> with we inject stem cells in the spinal cord, the stem cells surround those large nerve cells and allow those nerve cells to actually become less deceased. in fact, the nerve cells begin to look healthy. >> it's worth pointing out that john is going into the operating room, how important today is, especially when they're trying to answer the most important questions at this point, are these cells safe.