Mayo did just what you described-they grew millions of stem cells and "introduced" them into the lungs of COPD sufferers. (As I said) only 5-10% really benefited. They (Mayo researchers) have "no clue" as to why the results weren't better. Mayo is planning to re-run the trial as early as this summer. I have asked to be included. While the people who obtained significant improvement was small, no one has had adverse side-effects. I understand that is because we use our own stem cells "foreign" or donor cells are not used so rejection wouldn't be a side effect. However, I understand that the quality of the stem cells may be related to the extent inf lung injury, therefore severe lung damage may not be suitable for effective stem cell harvesting-but that is something I read in the literature. I have no medical training, and the Mayo researcher I spoke with did not offer that as a reason for the disappointing result.