WEDNESDAY, June 6 , 2001 (HealthDayNews) -- Medical dogma that says a heart cannot regenerate itself is wrong, a new study contends. Researchers say the organ experiences major new growth after a heart attack, a finding that could eventually pave the way for new treatments for heart-attack patients.
"The paradigm that the heart is made up of cells not capable of regeneration is wrong, despite the fact that the majority of cardiologists in the field claim that is not the case," says the study's lead author, Dr. Piero Anversa, who is the director of the Cardiovascular Research Institute at New York Medical College. "Unequivocally, there is a significant amount of regeneration of heart cells after a heart attack."
Other scientists are more cautious, however, saying that the research results have to be duplicated elsewhere before they can be offered as proof, and that there still may be huge obstacles to using the regeneration idea in any therapy.
This latest study builds on their previous research into dividing heart cells and suggests that the new cells may come from special stem cells in the heart, Anversa says. Stem cells are primitive cells that have the ability to develop into almost any kind of specialized cells. The hope is that doctors could manipulate stem-cell growth to revive the heart's dead sections. In a heart attack, blood flow is pinched off, and if the parts of the heart starved for blood don't receive any within three hours, the tissue starts to die.
The study is sophisticated and scientifically sound but so radically counters previous theory that it needs to be replicated, says Dr. Howard Eisen, medical director of the Advanced Heart Failure and Transplant Center at Temple University Hospital in Philadelphia. "It is a new paradigm," he adds. "We've all assumed all along that the heart can't regenerate, and that we were born with the cells we would be raised with."
About 1.5 million Americans have heart attacks each year, and approximately one third of them die, according to the Harvard Medical School. In the course of a typical attack, between 10 percent and 40 percent of the heart is killed; cardiologists believe you can't survive if more than 46 percent of the heart has been affected, Anversa says.
In the study, published in the June 7 New England Journal of Medicine, Anversa and others examined the hearts of 13 people who had died 4 to 12 days after massive heart attacks and compared them to the hearts of 10 people who had died of something other than cardiovascular disease. All the victims were of similar ages.
Unlike the healthy hearts, the damaged hearts showed marked signs of cell division and growth, particularly in areas near the damage that resulted from the heart attack. There was enough regeneration, Anversa says, that theoretically the number of cells lost in the heart attack could be replenished in about 20 days.
Anversa says this may help explain in part how the heart tries to compensate following a heart attack; typically, other areas of the organ try to pick up lost function. But the real hope, he adds, is that if the cells do indeed come from the heart's own stem cells, those cells might eventually be directed into the actual area of dead heart tissue to promote growth there.
"We could direct these cells into the area of the infarct [heart attack] to regenerate the infarct," Anversa says. "We may be able to recover significant parts of the human heart."
That would be exciting news, Eisen from Temple University Hospital says. But even if it's true, it presents possibly insurmountable challenges.
Other studies are showing that stem cells taken from other areas of the body -- the marrow, for instance -- promote growth in the heart; getting stem cells from the heart itself might prove dangerous and complicated because doctors would have to invade the heart to harvest them.
Nonetheless, Eisen says, the theoretical aspect of the study is important: if the results are replicated, it will change how doctors and researchers see the heart.
What To Do
If you or someone close to you has suffered a heart attack, you can find tips on how to prevent further damage at the American Heart Association. And you can read more about stem cell research at the National Institutes of Health.
And for more of the latest research on the human heart, try HealthDay.
