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WEDNESDAY, Feb. 24 (HealthDay News) -- Researchers are moving ahead -- although sometimes ploddingly -- toward the goal of using stem cell therapies to rescue people with cardiovascular disease, the leading killer of men and women in the United States.
Although much of the gains thus far have been in basic science, stem cells do seem close to actually being able to help actual humans.
"We have seen consistent but modest effects of stem cells in improving heart function and reverse remodeling of heart," said Dr. Gordon Tomaselli, a spokesman for the American Heart Association and an associate professor of medicine at the Johns Hopkins University School of Medicine in Baltimore.
"I think there's great hope," added Dr. Darwin J. Prockop, director of the Texas A&M Health Science Center College of Medicine Institute for Regenerative Medicine at Scott & White in Temple.
Several studies presented last November at the annual scientific sessions of the American Heart Association in Orlando serve as examples.
In one study, out of Germany, 35 patients who received bone-marrow stem cell transplantation during coronary artery bypass surgery achieved "excellent long-term safety and survival."
Ten patients who received similar transplantations after repair of mitral valves also fared well, with improvements in the heart's pumping capacity.
Slovenian investigators had similar success, with improvements seen in patients with advanced heart failure who received bone-marrow derived stem cells.
There were also advances in gene therapy reported, with Singaporean researchers using nanotechnology to deliver genetically modified cells to help heal heart attack damage in rabbits.
The stem cell promise hinges on the ability to produce unlimited supplies of human cardiac cells, experts say.
Kevin Eggan, chief scientific officer for the New York Stem Cell Foundation and associate professor of stem cell and regenerative biology at Harvard University, noted two breakthrough treatments that would require steady production of stem cells.
One is a future "patch" made out of these cells to fix a damaged heart after a heart attack. Researchers also hope to fashion blood vessels out of stem cells for use in bypass surgery and other procedures.
"People are making very substantial progress in being able to make those various vascular cells you would need," Eggan said. "Transplanting those is something that will come from all of this."
More immediately, perhaps, is the use of stem cells to screen heart drugs, sort of like test-driving the drugs in preclinical trials, Eggan said.
"You can do this in a couple of different ways," Eggan said. Researchers could determine in a laboratory dish if a drug actually works on heart cells, he said. The other method would involve manufacturing heart cells for a variety of people to find out which cells the drugs work on.
"One of the tricky things about drug trials is they often don't work on all people equally well," Eggan explained. "You have to study a whole lot of people to be able to see any sort of effects. This would screen out people that the drug doesn't work on. It would enable personalized medicine."
One innovation that is close to market, Eggan said, is a method for identifying and eliminating toxic drugs before they go into clinical trials.
A system is in the works that would involve testing drugs on heart muscle cells in a lab dish.
"This could save enormous time and money in clinical trials," Eggan said.
Gene therapy has not advanced as far, he added, but predicts that it will combine with stem cell therapies in the future.
"The one good thing that really has come out is that nobody has been harmed by [the stem cell] therapies," Prockop pointed out.
The U.S. National Institutes of Health has more on stem cells.