better known as lou gehrig's disease. the nerve cells in the spine and brain which control muscle movement destroyed. and when the brain can no longer tell muscles to move, the muscles wither wear. 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's no cure for als. so does his wife and two daughters. >> my first thoughts were i hated for my girls to see me go through this. 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. a lot of issues here. dr. feldman developed the trial. >> when we inject stel cremes in the spinal cords, the stem cells surround the large nerve cells