Transplanting One's Own Stem Cells into Heart Decreases Pain

The largest U.S. stem cell study for heart disease showed the first evidence that transplanting a potent form of adult stem cells into the heart muscle of subjects with severe angina results in less pain and an improved ability to walk. The transplant subjects also experienced fewer deaths than those who did not receive stem cells.

In the 12-month phase II, double-blind trial, the subjects' own purified stem cells, called CD34+ cells, were injected into their hearts in an effort to trigger the growth of small blood vessels that comprise the microcirculation of the heart muscle. Researchers believe the loss of these blood vessels adds to the pain of chronic, severe angina.

"This is the first study to show significant benefit in pain reduction and improved exercise capacity in this population with very advanced heart disease,” said lead investigator Douglas Losordo, M.D., professor of heart research at the Northwestern University Feinberg School of Medicine (Chicago, IL, USA), a cardiologist and director of the program in cardiovascular regenerative medicine at Northwestern Memorial Hospital (Chicago), the lead site of the study.

Dr. Losordo reported that this study provides the first evidence that a person's own stem cells can be used as a treatment for their heart disease. He cautioned, however, that the results of the 25-site trial with 167 subjects require verification in a larger, phase III study. He presented his findings November 17, 2009, at the American Heart Association Scientific Sessions 2009, held in Chicago, IL, USA.

Out of the estimated one million people in the U.S. who suffer from chronic, severe angina--chest pain due to blocked arteries--approximately 300,000 cannot be helped by any conventional medical treatment such as angioplasty, bypass surgery, or stents. This is called intractable or severe angina, the severity of which is designated by classes. The subjects in Dr. Losordo's study were class 3 or 4, meaning they had chest pain from normal to minimal activities, such as from brushing their teeth or even resting.

The stem cell transplant is the first therapy to produce an improvement in severe angina study participants' ability to walk on a treadmill. Twelve months after the procedure, they were able to double their improvement on a treadmill compared to the placebo group. It also took twice as long until they experienced angina pain on a treadmill compared to the placebo group, and when they felt pain, it went away faster with rest. Moreover, they had fewer overall episodes of chest pain in their daily lives.

In the trial, the CD34+ cells were injected into 10 locations in the heart muscle. An advanced electromechanical mapping technology identifies where the heart muscle is alive but not functioning, because it is not receiving enough blood supply.

The study was supported by Baxter Healthcare Corp. (Deerfield, IL, USA).

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Northwestern University Feinberg School of Medicine