Patients with severe heart disease often run out of treatment options.
Many live with intense chest pain and are confined to their homes.
Now, doctors are studying whether injecting them with their own stem cells will help their hearts re-grow muscle.
Bill Spence is 52-years-old, had two heart attacks, open heart surgery, a pacemaker, and several stents.
He takes more than 25 drugs each day.
Now, Bill is one of 33 people in a stem cell study.
Patients are injected with a drug that helps the body release stem cells.
A special machine isolates the cells from their own blood.
Doctors use a mapping system to inject stem cells back into weak areas of the heart.
The idea is to grow new blood vessels.
Dr. Gary Schaer of the Rush University Medical Center stated, "I see the potential for helping many people that otherwise would not benefit from any conventional therapy."
In the pilot trial, more than 60% of patients reported less chest pain.
Right now researchers are enrolling people in about eight centers across the country.