Potential for Adult Stem Cells to Repair Hearts Damaged by Severe Coronary Artery Disease
Rush University Medical Center is one of the first medical centers in the country, and currently the only site in Illinois, participating in a novel clinical trial to determine if a subject'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 in the U.S. designed to investigate the efficacy, tolerability, and safety of blood-derived selected CD34+ stem cells to improve symptoms and clinical outcomes in subjects with chronic myocardial ischemia (CMI), a severe form of coronary artery disease.
"What we're hoping is that these stem cells will be able to stimulate the growth of new blood vessels to bring more blood and oxygen to the heart muscle, so that these patients will have a better quality of life and less chest pain," said Dr. Gary Schaer, director of the Rush Cardiac Catheterization Lab and study investigator.
Myocardial ischemia is a serious heart condition that involves narrowing of coronary arteries and results in limited blood flow to the heart. The disease affects hundreds of thousands of new people each year. A person who suffers from chronic myocardial ischemia continues to experience insufficient flow of oxygen-rich blood to the heart despite optimum medical intervention.
The study is a randomized, double-blind, placebo-controlled study that involves adult subjects with severe coronary artery disease who are currently on the maximum medical therapy and who are not suitable candidates for conventional procedures to improve blood flow to the heart such as angioplasty, stents, or coronary artery bypass surgery.
Rush is one of 15 to 20 research sites nationwide participating in the study, which is sponsored by the Cellular Therapies business unit of Baxter Healthcare Corporation. Baxter technology is used to select the subject's own CD34+ stem cells that are under investigation in this trial.
The baseline frequency and severity of anginal episodes are established as a first step for all study subjects. Next, all subjects receive a series of subcutaneous injections (needle shots, typically delivered under the skin in the arm, thigh or abdomen) of a commercially produced protein (granulocyte colony stimulating factor). The protein helps to release CD34+ stem cells (also known as endothelial progenitor cells) from a subject's bone marrow into the bloodstream.
Then, investigators use a cell separation system, similar to the automated systems that are used with people who donate specific blood components such as platelets or red blood cells, to collect from the subject's bloodstream, an enriched preparation of cells that contain CD34+ stem cells. When this process, known as apheresis, is complete, technologists further process the collected stem cells with Baxter's ISOLEX 300i Magnetic Cell Selection System, currently approved for use with cancer patients, to select the subject's CD34+ stem cells for use in this investigational therapy.
Schaer then uses a catheter-based, non-surgical system to map the patient's heart three-dimensionally to identify the damaged areas into which the stem cells would be injected. "This targeted approach increases the treatment's effectiveness by delivering the stem cells exactly where they are needed." Schaer uses the Johnson & Johnson's NOGA XP Cardiac Navigation System to identify ischemic but viable regions of the heart as targets for cell delivery. The researchers then use a special investigational catheter that functions like a "global positioning system" to precisely deliver CD34+ cells, or placebo, into the areas of the heart that have been identified as having poor blood flow.
Subjects are randomly selected to receive either one of two dosing levels of CD34+ stem cells, or placebo. Rush researchers will conduct follow-up examinations for 12 months.
Researchers are encouraged by reports that the therapy appeared to be well-tolerated and no serious adverse events directly related to the stem cell therapy in an earlier study. According to preliminary, anecdotal patient reports, 16 of the 24 total Phase I study subjects reported feeling better with reductions in chest pain and improved exercise capacity during the early stage of the trial.