"An experimental procedure aimed at repairing spinal cord injuries is showing promise. It uses stem cells in the damaged areas in hopes of restoring function and movement.    And for one patient it is promising.    On April   James Mason was an accident waiting to happen.    There was nothing we could have done to change that night said Bob Gambuti.    During an argument James Masons stepfather Bob Gambuti tried to stop him from getting into a car after Mason had been drinking.    He grabbed onto me I grabbed onto him said Gambuti. He pulled my leg out and we fell back and his neck broke.    CBS News    I remember just hitting the ground said Mason. I remember the whole way with the stretcher.    Gambuti said the most devastating part of the whole process was the first day that they lifted Mason out of a bed.    And nothing moved Gambuti said. Just his head. That really hit hard. At that point I really wanted to go jump off a bridge.    Mason was left a quadriplegic with just the slightest ability to move his arms. Doctors said he would never walk again.    Gambuti a retired cop became his full time caregiver and found an experimental trial at New Yorks Mount Sinai Hospital.    CBS News spoke with Mason just before he underwent delicate neck surgery to try and repair the demaged part of his spinal cord by injecting stem cells.    CBS News    Im just super excited ready to just get it done and go back to rehab and start proving the doctors wrong even more said Mason.    The surgery performed by Dr. Arthur Jenkins took four hours. Researchers have followed Mason and five other patients  all with the most severe spinal cord injuries.    CBS News met up with Mason again three months after the surgery.    Mason said he was already noticing changes.    My wrist has gotten a lot stronger. Im able to grasp around a lot other things he said.    CBS News    And after six months he was noticing changes then too.    I think its almost doubled with how much Ive gotten better he said. And got sensation back into my feet. I can feel pressure onto em throughout my legs. And theyve noticed that I have a little bit of movement into my hips now.    Today the company sponsoring the trial reported four of the six patients experienced improvement in both motor strength and function. Dr. Jenkins who is not affiliated with the company has continued to monitor Mason.    My two cents is it worked that this actually changed his neurological recovery and function Dr. Jenkins said. That his actual functional improvement is from the stem cells that were injected.    Whats that like for Mason    I mean I just have to keep pushing forward he said.    Mason does not blame his stepfather for the accident in fact he is grateful.    If I had gotten into my car I could have killed someone else someones mother someones father someones child. If I would have survived through that I wouldnt have been able to live with myself he said.    Its odd and its tough and people say Im sorry. Dont be sorry. I still have him here Gambuti said.    Mason believes the stem cells accelerated his recovery. But its hard to know what would have happened without them. More research will be needed to try to establish whether they actually repair damage to the spinal cord."