Shot to the Heart, Before It's too Late
While several smaller studies have suggested that injecting stem cells into damaged heart tissue might be effective, this study, in its scope and rigor, was the first of its kind. A total of 167 patients were recruited and randomly assigned to receive a lower dose of stem cells, a higher dose or a placebo. The patients didn't know who got what treatment, and neither did the doctors treating them.
When tracked for a year after the injection, patients who received the lower dose of stem cells could last longer during a treadmill exercise than those who had received the placebo, and they averaged seven fewer episodes of chest pain in a week. To put this in perspective, a popular drug to treat angina, Ranolazine, reduced chest pain by fewer than two episodes a week in clinical trials.
Although the goal of the stem cell shots was to grow new blood vessels, it's impossible to tell if these stem cells were actually growing into blood vessels or if they were just triggering some other kind of healing process in the body, Henry says. Tests in animal models, however, do suggest that new blood vessels are forming, says Dr. Marco Costa, a co-author of the study and George Reed's doctor at UH Case Medical Center in Cleveland.
For now, the only gauge of the injections is improvement in symptoms.
Despite the positive results of the study, cardiologists remain "cautiously optimistic" about stem cells as a treatment for angina.
"The number of patients is relatively small, so this trial would probably not carry much scientific weight," says Dr. Jeff Brinker, a professor of cardiology at Johns Hopkins University. The results did justify the next, larger trial, he says, which would offer more answers as to whether this treatment is actually working the way researchers suspect.
The fact that lower doses of stem cells were puzzlingly more effective than larger ones is cause for caution, says Dr. Steve Nissen, chairman of the department of cardiovascular medicine at the Cleveland Clinic.
"The jury is still out for stem cell therapies to treat heart disease," says Dr. Cam Paterson, a cardiologist at the University of North Carolina at Chapel Hill.
But the results so far provide cautious hope for heart patients like George Reed and Jay Homstad.