Stem Cells May Improve Heart Bypass Results

US News and World Report, November 17, 2009

The bone marrow is conventionally thought of as the location in the body where blood is made. Production of blood is regulated by the body's needs and originates from a specialized type of stem cell called the "hematopoietic" stem cell.

There have been numerous studies demonstrating that the bone marrow also contains stem cells that are capable of regenerating injured heart tissue. Controversy exists as to which specific type of bone marrow stem cell is better at regenerating heart tissue, however the concept is not new. Back in 1999 researchers from the University of Toronto in Canada demonstrated that subsequent to induction of cardiac injury in laboratory rats, the injection of bone marrow stem cells that have been treated with a chemical agent (5-azacytidine) would cause significant recovery of the injury [1]. Treatment with the chemical agent resulted in cells that resembled heart cells in the test-tube, which were subsequently transplanted into the animal.

Later studies showed that for certain types of heart injury it was not necessary to treat the bone marrow stem cells with chemical agents, but that simple administration of these cells, either directly into the heart [2], or intravenously [3], was able to cause a therapeutic response.

Today at the American Heart Association's Annual Meeting in Orlando Florida researchers from the University of Rostock presented data using stem cells from the bone marrow together with coronary artery bypass surgery in treating patients with heart failure due to poor circulation.

The researchers presented data on 10 patients that were administered a purified population of bone marrow stem cells. These stem cells were selected using a magnetic-based approach for expression of the protein CD133, which is associated with enhanced stem cell activity. The purpose was to increase circulation by causing formation of new blood vessels, as well as possibly increasing ability of the heart muscle to regenerate.

The study demonstrated efficacy in the treated patients based on increase cardiac muscle contraction ability as compared to patients that had bypass surgery but did not receive stem cells. However the number of subjects was too small to draw definitive conclusions. No treatment associated adverse effects were noted.

1. Tomita, S., et al., Autologous transplantation of bone marrow cells improves damaged heart function. Circulation, 1999. 100(19 Suppl): p. II247-56.

2. Barile, L., et al., Bone marrow-derived cells can acquire cardiac stem cells properties in damaged heart. J Cell Mol Med, 2009.

3. Krause, U., et al., Intravenous delivery of autologous mesenchymal stem cells limits infarct size and improves left ventricular function in the infarcted porcine heart. Stem Cells Dev, 2007. 16(1): p. 31-7.