Healing The Heart With Bone Marrow Cells

July 5, 2006

Researchers at the McEwen Centre for Regenerative Medicine at Toronto General Hospital have discovered the 'SOS' distress signal that mobilizes specific heart repair cells from the bone marrow to the injured heart after a heart attack.

While it has long been known that bone marrow cells have the ability to clear the dead tissue after a heart attack, what has not been known until now is the critically important role of bone marrow adult stem cells in repairing a damaged heart, restoring its function and enhancing the growth of new blood vessels.

"These cells act like generals in a battlefield, explained Dr. Shafie Fazel, cardiac surgery resident at TGH, University of Toronto surgeon/scientist program fellow and lead author of the study entitled, "Cardioprotective c-kit+ cells are from the bone marrow and regulate the myocardial balance of angiogenic cytokines," published today in The Journal of Clinical Investigation. "When damaged heart tissue sends out an 'SOS' distress signal, this subset of bone marrow cells mobilizes quickly and stimulates the growth of new blood vessels in the heart. This is the first step in repairing the heart and in preventing the vicious downward spiral of heart failure in which the heart progressively thins and dilates, eventually causing death." Despite advances in surgical procedures, mechanical assistance devices, drug therapy, and organ transplantation, more than half of patients with congestive heart failure die within five years of initial diagnosis.

"Cardiovascular diseases are the most important cause of mortality in Canada and the western world," said Dr. Ren-Ke Li, scientist at the McEwen Centre for Regenerative Medicine and Professor of Cardiovascular Surgery at the University of Toronto. "Each year, 70,000 Canadians suffer from a heart attack and many of them are left with crushing disabilities, mainly because the heart muscle is not able to regenerate after a heart attack. This study identifies the method the body employs to repair the heart and provides new therapies to stimulate cardiac regeneration and prevent heart failure in patients who have suffered a heart attack," noted Dr. Li, who is also a Canada Research Chair in Cardiac Regeneration. The research was performed in Dr. Li's laboratory.

Dr. Li's team used genetically-engineered mice in which bone marrow cells were modified to carry a green fluorescent marker allowing researchers to easily track them. The researchers demonstrated that these bone marrow cells are quickly mobilized to the damaged heart region following a heart attack. Once in the damaged area, the cells produce chemicals that trigger the growth of new blood vessels -- an important step in repairing the injured heart.

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This article posted August 19, 2006.