ANAHEIM, Calif., Nov. 12 – In the first study of its kind, researchers have used a person’s own bone marrow cells to improve blood flow in otherwise untreatable coronary arteries, according to research presented today at the American Heart Association’s Scientific Sessions 2001 conference.
Kimikazu Hamano, M.D., and his colleagues reported results from an ongoing clinical trial in which five patients received injections of their own bone marrow cells into oxygen-starved areas of their hearts. Three of these patients later had increased blood flow in these areas. "We found this new treatment to be safe, and we believe it could be an alternative treatment for heart patients who cannot be helped by coronary artery bypass surgery or balloon angioplasty," says Hamano, a lecturer at the Yamaguchi University School of Medicine in Ube, Japan. Bypass surgery and angioplasty can improve blood flow to the hearts of many patients whose coronary arteries are clogged and narrowed by fatty deposits. But others cannot be helped at all or portions of their heart cannot benefit from the procedures. This is often because their heart disease is too widespread.
Injecting adult stem cells from the patient’s own bone marrow is easy, relatively inexpensive and appears to have no side effects, Hamano says. Stem cells are basic building block cells that can grow into specialized cells in the body, such as heart cells, nerve cells and organ cells. The Japanese team began their human trial after a series of animal experiments. The first patient was injected with his own bone marrow cells in November 1999.
"We have good results from these experiments in animal studies," Hamano says. "The aim of the current trial is to confirm the safety and efficacy of this treatment in humans." He and his colleagues selected their study participants from among patients who were scheduled to undergo bypass surgery. Their five patients had an average age of 66 and all suffered severe and debilitating chest pain (angina). They were chosen because areas of their heart muscle could not receive any benefit from the bypass surgery.
As surgeons began bypass surgery on each participant, the researchers withdrew bone marrow from the patient’s hip bone. From this harvested marrow, they prepared a mixture rich in mononuclear cells, which includes immature cells such as stem cells and the precursor cells of the endothelial cells that line the inner walls of blood vessels.
Depending on the size of the area of heart muscle treated, the patients received between five and 22 injections of cells into the heart muscle, administered 1 centimeter (0.39 inch) apart. The patients were examined one month after their injections/operations using a nuclear medicine test called cardiac scintigraphy. Scintigraphy measures coronary perfusion, which is the amount of blood flowing to the heart. All of the patients have been followed for at least one year.
Three of the five patients showed marked improvement in blood flow to the parts of their heart treated with bone marrow. Their severe chest pain also had disappeared. The other two patients, however, had no change in blood flow compared to preoperative tests. Chest X-rays, blood tests, electrocardiography, and ultrasound studies did not reveal any detrimental changes in any patients.
Despite evidence in three patients of increased blood flow in the treated areas, “It was difficult to clearly identify new vessels formed by this treatment on postoperative angiograms,” Hamano says. Angiography uses a combination of X-rays and a dye injected into the heart’s arteries to visualize the organ’s blood vessels. However, this failure to detect new vessels did not surprise the researchers.
"From our experimental data, the new vessels formed as the result of bone marrow cell injections were only 30 to 60 micrometers (about 0.00117 to 0.00234 inch) in diameter," Hamano explains. "The detection level of blood vessels by angiography is more than 200 micrometers. Therefore, it is understandable that we could not see the new vessels."
The important finding, he says, is the evidence of greater blood flow to the heart muscle. Hamano and his colleagues have now treated a sixth patient as part of their continuing study. Co-authors are: Masahiko Nishida, M.D.; Ken Hirata, M.D.; Akihito Mikamo, M.D., Ph.D.; Tao-Sheng Li, M.D., Ph.D.; Kensuke Esato, M.D., Ph.D.; Masahiko Harada, M.D., Ph.D.; and Toshiro Miura, M.D., Ph.D.
Materials provided by American Heart Association. Note: Content may be edited for style and length.
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