By: Shelagh McNally for Heart1This year, just over 1.1 million Americans will have a heart attack. While fewer people are dying during their acute phase – thanks to breakthroughs in medicine, therapies, transplants and medical devices – almost half of these patients will die within five years from congestive heart disease. The heart does not easily recover and for many years, doctors have been looking at how to rejuvenate it. The answer may lie in bone marrow stem cells.
Several clinical trials in both Canada and Europe have shown promising results using bone marrow cells. We’ve known for a while that bone marrow cells have the ability to clear dead tissue after a heart attack, but it was never clear how they operated. Research conducted at McEwen Centre for Regenerative Medicine at the Toronto General & Western Hospital (TGH) Foundation has made an important first step towards unraveling the mystery. The research project, lead by Dr. Ren-Ke Li, used genetically engineered mice with modified bone marrow cells. These cells had green fluorescent markers, allowing them to be tracked easily. Not only were researchers able to watch the bone marrow cells at work during a heart attack, but they also identified a specific molecule that plays a crucial role. Dubbed the c-kit, this molecule acts like a switch that is turned on by signals from the heart. Once activated, the c-kit molecule sends a signal to the bone marrow cells to migrate to the heart and start repairs.
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Symptoms of congestive heart failure:
Swelling of legs, ankles, or abdomen
Shortness of breath- especially when lying down
Increased urination
Nausea, abdominal pain, or decreased appetite
Fatigue
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“These cells act like generals in a battlefield,” explained Dr. Shafie Fazel, a cardiac surgery resident at TGH, University of Toronto and lead author of the study. “When damaged heart tissue sends out an ‘SOS’ distress signal, bone marrow cells mobilize quickly and stimulate 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.” The study was an important first step toward new strategies for repair and regeneration of the heart after an attack. Results of the study were first published in the July edition of The Journal of Clinical Investigation Three separate studies published in the September 21, 2006 issue of The New England Journal of Medicine support the findings from Toronto. While none of the studies were conclusive, all three showed a correlation between when the bone marrow cells were given and the rate of healing. The first double-blind clinical trial of bone marrow stem cells is now underway in Britain at the London Chest Hospital, part of Bartholomew's Hospital (Bart’s) and at the London Heart Hospital, part of the University College Hospital (UHC). One hundred patients with heart problems are involved; half of the patients will be given injections of bone marrow stem cells extracted from their hip. The other half will receive a placebo. Neither the patients nor doctors will know who is receiving the actual cells. After two years, each patient’s heart will be assessed to see how well it’s pumping and whether there has been any rejuvenation.
Stem-cell research is a controversial business these days, but Anthony Mathur, senior lecturer and consultant cardiologist at Bart’s stated, “If we can demonstrate improvement in the quality of life of patients, then this will be a significant step forward in the treatment of heart disease. Because the stem cells are taken from the patient, there are minimal ethical issues surrounding this procedure. There is also less likelihood of rejection complications.”
For the millions of Americans suffering from heart disease, hope may come from deep in their bones.
