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Heart Disease News (dateline May 11, 2001)


Scientists recently made a promising advance in heart disease research when they discovered that it is possible to repair cells damaged from a heart attack with adult stem cells taken from the bone marrow of mice. The research, conducted by scientists at the National Institutes of Health (NIH) and New York Medical College, is the first of its kind to show that stem cells could become functional heart muscle cells. Though the research is in preliminary stages, the scientists are encouraged by the positive results and see great potential for using adult stem cells in treating human patients.

"This study offers hope that we might one day be able to actually reverse the damage caused by a heart attack," said Francis S. Collins, MD, PhD, Director of the National Human Genome Research Institute, in an NIH news release. "The apparent ability of stem cells in the bone marrow of adult animals to rebuild the heart reveals nature’s remarkably flexible response to disease."

Stem cells are relatively undifferentiated cells that are present in muscle, skin, and various other tissues. Stem cells retain the ability to divide and become specialized to take the place of other cells that die. Research continues to show that both adult stem cells and those from embryos may be very useful in helping to repair damage caused by several conditions, including bone injuries, Parkinson’s disease, and diabetes. Because research using human embryos remains controversial, scientists are continuing to explore how they might use a patient’s own stem cells to repair damage caused by disease.

In this recent study, researchers Donald Orlic, PhD, Piero Anversa, MD, and their colleagues began by isolating stem cells from the bone marrow of male mice. Then, they induced heart attacks in the female mice by tying a suture around the coronary artery to induce blockage similar to that found in heart attack patients. After the female mice suffered heart attacks, the scientists injected the male mice’s stem cells next to the damaged tissue in the female mice. Seven to 11 days later, Dr. Orlic’s team found that the stem cells began to multiply, transform into heart muscle cells, and migrate into 68% of the damage area of the heart. The adult stem cells also produced additional cells that formed new blood vessels.

"Our expectations were far exceeded in terms of seeing not just heart muscle cells, but blood vessels and functional measurements showing that the repair actually improved cardiac output. It was a wonderful surprise…" said Dr. Orlic, in an NIH news release.

However, the procedure was only successful in 12 out of the 30 mice (40%). The scientists attribute this to the difficulty of injecting stem cells into the female heart that beats approximately 600 times each minute. However, follow-up studies are already in the works and if they prove successful, Dr. Anversa estimates that human trials may begin in as little as three years. Dr. Orlic, Anversa, and their research team are especially encouraged by how the new cells are able to restore the heart’s ability to pump blood, which is important for treating human heart attack patients.

Heart attacks (myocardial infarction) can occur in patients who have coronary artery disease, a condition in which the arteries become blocked with cholesterol deposits. If this blockage is severe, the blood flow to the heart is severely limited or interrupted and a heart attack occurs. Coronary artery disease is the leading cause of death among both men and women in the United States and in Europe. Approximately 12,800,000 Americans suffer from coronary artery disease and nearly 500,000 Americans die from heart attacks caused by coronary artery disease. Over 12 million Americans have a history of heart attack, chest pain (angina), or both.

The risk of coronary artery disease increases with age and is higher among people with a family history of heart disease. High blood pressure (hypertension), high cholesterol, smoking, diabetes, obesity, lack of physical activity, and stress are all factors that can increase the risk of coronary artery disease. Women and men should receive regular physical exams and ask their physicians about how they can minimize their risk of coronary artery disease and other heart problems.

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