Researchers investigating potential for adult stem cells to repair damaged hearts (11/6/2007)

Mayo Clinic is one of a select group of medical centers in the U.S., and the only medical center in Arizona, enrolling patients in a novel clinical trial investigating whether a patient's own stem cells can treat a form of severe coronary artery disease. The Autologous Cellular Therapy CD34-Chronic Myocardial Ischemia (ACT34-CMI) trial is the first human phase II adult stem cell therapy study for heart disease in the U.S. designed to investigate the efficacy, tolerability and safety of blood-derived stem cells to improve symptoms and clinical outcomes in patients with chronic myocardial ischemia (CMI), a severe form of coronary artery disease.

CMI develops when the coronary arteries become so diseased that they limit the flow of blood to the heart and send small blood clots downstream, blocking the small blood vessels in the heart. These blockages can result in a series of mini-heart attacks that may be too small to notice at the time, but in aggregate may cause significant long-term damage to the heart muscle and disability to the patient. While cardiologists can restore blood flow in some cases, the heart muscle can be irreversibly damaged, leading to significant disability, progressive heart failure and often death.

The type of therapy used in this trial is called regenerative medicine. The goal of using this approach is to promote either the growth of new capillaries or arteries or the maturation and enlargement of existing arteries.

The first step in the ACT34-CMI trial is to establish a baseline of how often patients have chest pain and define the severity of their pain. Then patients receive a series of injections of a commercially produced protein that helps release CD34+ stem cells from their bone marrow into their bloodstream.

After the series of protein injections, blood is drawn from patients, and using a cell separation system, the CD34+ stem cells are removed from the blood. Using a non-surgical, catheter-based system, Mayo Clinic physicians will inject either the extracted stem cells, or a placebo, into the areas of the patient's heart with poor blood flow. Follow-up examinations are conducted for 12 months following the injections of stem cells. Based upon encouraging results gathered in an earlier trial, doctors hope to see a reduction in chest pain and improved exercise capacity in some patients.

ACT34-CMI is a prospective, randomized, double-blind, placebo-controlled study. Mayo Clinic is enrolling adult patients with severe coronary artery disease who are on medical therapy and are not suitable candidates for conventional procedures to improve blood flow to the heart, including angioplasty, stents or bypass surgery. Mayo Clinic is one of approximately 20 research sites participating in the study, which is sponsored by the Cellular Therapies business unit of Baxter Healthcare Corporation, the maker of the equipment that selects the CD34+ stem cells.

Note: This story has been adapted from a news release issued by the Mayo Clinic

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