admiration and respect for being willing to do this for the greater good. reporter: the greater good. you see, john has volunteered to be one of the first people in the united states to participate in an operation to inject stem cells directly into his spine. it s called a phase one clinical trial. this is the first step. no one knows what will happen. here s how john got to this place. two years ago i was running, playing golf. reporter: gradually, literally, he began to lose it. i started tripping and kind of like a foot drop and started catching my foot on bricks and curbs and started losing my balance initially. and then developed a limp in my right leg. i lost the decks airty where you can t button buttons, tie shoes. i can kick a little bit, but i can t really pick my legs up.