(Writes through with results of four new studies; changes dateline from WASHINGTON) By Maggie Fox, Health and Science Correspondent ORLANDO, Florida, Nov. 10 (Reuters) - A patient's own cells might some day be used to rebuild a heart damaged by heart attack or long-term heart disease such as heart failure, researchers reported on Monday. Several early experiments being presented to a meeting of the American Heart Association are looking at the possibility that immature cells in a patient's own body can be used to reverse or prevent some of the damage caused by heart attack or heart disease. German researchers showed that cells taken from the bone marrow and washed into the heart soon after heart attack helped patients recover better than patients given standard care. The 30 patients who got the cells had an average 6.7 percent improvement in left ventricular ejection fraction -- meaning their hearts pumped much more efficiently."It is a highly significant improvement," Dr. Helmut Drexler of Hannover Medical School, who led one of the studies, told a news conference. Dr. Ray Gibbons of the Mayo Clinic in Rochester, Minnesota, said a 6.7 percent improvement could be enough to tip a patient over from questionable survival to long-term survival. The 30 patients who got angioplasty alone had, on average, only a 1 percent improvement in ejection fraction. In a second study Dr. Bodo Strauer of Heinrich Heine University in Dusseldorf and colleagues tested 40 heart attack patients -- half of whom got bone marrow cells. They found that the patients given stem cells seemed to regenerate new heart tissue. The damaged area shrank, and the heart's pumping ability improved. Dr. Emerson Perin and colleagues at Baylor College of Medicine and the University of Texas Health Science Center in Houston injected a certain type of stem cell called CD34 cells directly into the hearts of heart failure patients. All could later exercise -- after being barely able to walk around their homes. "They're functional and they have their lives back," Perin said. Five patients who were waiting for heart transplants are now off the transplant list, he said. LOOKING FOR THE BEST CELLS One key question is what kind of cells are best to use. The researchers believe, but are not sure, that the work is being done by stem cells -- immature cells that can give rise to several different cell types. Bone marrow is rich in them. Drexler said he believes the cells go directly to the damaged area, which, right after a heart attack, would have still been sending out distress signals. Some may become heart muscle cells. They may also stimulate stem cells that live in the heart to divide and grow, form tiny blood vessels to feed the tissue and perhaps also secrete proteins that stop damaged tissue from dying. Another team sought to find the best possible cell for this job, out of all the different cells found in bone marrow. Dr. Young Sup Yoon and colleagues at Tufts University in Boston singled out a never-before-seen stem cell that they called human bone marrow derived multipotent stem cells. In rats given a heart attack, an infusion of these cells grew onto the heart. In the lab, they developed into a variety of different heart cells including heart muscle cells and blood vessel cells, Yoon told the conference. Yet another group decided to go straight for muscle cells and took little plugs of muscle from the thighs of patients with heart failure waiting for heart transplants. It was a very early and experimental trial but PET and MRI scans of the heart, which can image tissue and how it is working, showed renewed life in the transplant area. In three patients who got heart transplants later, examination of the old heart showed the muscle plugs had become part of the heart muscle, said Dr. Nabil Dib of the Arizona Heart Institute in Phoenix, who led the study. The researchers do not believe any of the approaches will be expensive -- perhaps double the cost of getting a standard angioplasty to stretch open a clogged artery. "Our own cells are free," Perin said. "It is not a very expensive procedure."
