(CBS) — We've heard a lot about stem cells and the promise of treating disease. But how far is it from reality?

A new study finds some patients are benefiting from adult stem cell therapy right now.

A review of hundreds of trials found in some patients adult stem cells have stopped auto-immune diseases like rheumatoid arthritis and multiple sclerosis.

Some heart patients like Donald Reid have also seen improvement.

New York-Presbyterian Hospital/Weill Cornell Medical Center’s Michael Schuster is excited by the results but warns it's still early.

"We don't know yet what the best technique is,” said Dr. Schuster. “We don't really know how much of a benefit the patients will have.”

And when it comes to diseases like diabetes, Alzheimer's and Parkinson's …

"I think we're still a few years away from knowing whether stem cells really turn out to be the answer,” Dr. Schuster said.

Donald should have an answer much sooner.

His wish: "To be like everyone else and not have to worry about that my heart might give out,” he said.

In the coming weeks he'll know if that wish came true.