High-Tech Treatments for the Heart
Researchers Grow New Arteries, Heart Cells
Valentin Fuster, MD, PhD, director of the cardiovascular institute at Mount Sinai Medical Center, New York, says the new vessel-growing technology is coming along at a time when it is sorely needed because the new emphasis on early detection of heart disease means that "many more patients are having many more procedures." This means that a rapidly growing number of heart disease patients have already run the gamut of available treatments.
Moreover, Fuster, who did not participate in McAllister's study, says that patients with diabetes may be particularly good candidates for this technology because they have widespread disease that affects their hearts as well as circulation in the legs. Another group that is likely to benefit is dialysis patients because after repeated dialysis treatments veins collapse and have to be replaced with vein grafts.
McAllister says that dialysis patients will actually be the first patients recruited for human studies because "this is not a life-threatening procedure in these patients." If those studies are successful, patients needing bypass procedures for blocked arteries in their legs will be studied and finally the engineered vessels will be tried in heart bypass surgery.
While McAllister is engineering new blood vessels, other researchers are using muscle and bone marrow cells to rejuvenate damaged heart tissue.
A heart attack scars the heart tissue, says heart surgeon Timothy Gardner, MD, University of Pennsylvania, who chaired a news conference on cell transplants. This "scarring" means that the heart can no longer efficiently pump blood throughout the body, so the patient can experience chest pain, fatigue, and difficulty breathing.
Cell transplant researchers inject either muscle cells or bone marrow cells directly into these scarred areas during heart surgery. The idea is that the implanted cells will change into cells that mimic the function of healthy heart cells.
Nabil Dib, MD, director of the cardiovascular research at the Arizona Heart Institute, Phoenix, used muscle cells taken from the legs of 16 heart patients. Each participant was undergoing either bypass surgery or having a mechanical pump implanted to improve heart function. During the surgery the cells were injected directly into the scarred area of the heart.
Three months later all the patients who received the cell transplants had improved pumping function, suggesting that leg muscle cells were now doing the work of native heart cells.
In a similar study using bone marrow cells Manuel Galinanes, MD, of the University of Leicester, U.K., had similar positive results when he injected 14 patients who had heart bypass surgery.
Gardner says the research is promising -- especially since it relies on cells donated from adults rather than cells from embryos -- but he cautions that it is very preliminary. He noted that some patients who receive these cell transplants can develop dangerous irregular heart beats.