DEBBIE ELLIOTT, host:
This is ALL THINGS CONSIDERED from NPR News. I'm Debbie Elliott.
One of the hottest areas of biomedical research today is something called regenerative medicine. The idea is that it may be possible to help the body regenerate organs or cells damaged by disease. Most of the research in regenerative medicine is focused on stem cells. Today, scientists are reporting that they can regenerate heart muscle cells in an animal that's had a heart attack.
NPR's Joe Palca explains.
JOE PALCA: There are a lot of parts of our body that can regenerate when they're damaged. Stem cells in our skin can make new skin cells if we suffer a cut. Stem cells in our bone marrow can make new blood cells if we lose some blood. The strategy of regenerative medicine is to help those processes along.
Charles Murry is at the University of Washington in Seattle. He's interested in using stem cells to fix damaged hearts.
Dr. CHARLES MURRY (Pathology, University of Washington): The fundamental problem is that the heart is arguably the least regenerative organ in the body. And so after patients suffers damage to their hearts, say, through a heart attack, instead of healing by growing back your muscle, the heart heals by scar tissue formation.
PALCA: And scar tissue doesn't contract the way heart muscle does. So the heart doesn't pump blood as well.
Dr. MURRY: The fundamental problem that we're working on is to try to improve the intrinsic way that the heart heals. And we're hoping that through harnessing the power of stem cells will actually one day be able to grow back new heart muscle and new blood vessels in patients with damaged hearts.
PALCA: Scientists haven't made much progress obtaining cardiac stem cells that would make the heart cells they'd like. So Murry and his colleagues have been using embryonic stem cells. Embryonic stem cells retain the potential determinant to any tissue type in the body.
In their first set of experiments, they coaxed human embryonic stem cells to turn into heart muscle cells, and then put those cells into healthy rats. The human cells took up residence in the rat heart and started contracting right along with the rat heart muscles. Then they transplanted the cells into rats with hearts damaged by induced heart attacks.
Dr. MURRY: We found when we went into the damaged heart as opposed to the normal heart, nearly all of the cells that we transplanted in died. And we couldn't overcome this by brute force by just simply putting in more cells. The more we pumped in, the more died.
PALCA: After some trial and error, Murry and his colleagues found a complex cocktail of chemicals that allowed the human cells to survive and help the damaged rat hearts beat more like normal. The results appear in the current issue of the journal Nature Biotechnology. It will be years before Murry's approach will be ready for studies in human patients.
But several teams around the world are also trying a kind of regenerative therapy using co-called adult stem cells taken from a patient's own bone marrow. These cells don't make heart muscle, but they do appear to be doing something beneficial. Douglas Losordo is conducting one of these experiments at Northwestern University Feinberg School of Medicine in Chicago.
Dr. DOUGLAS LOSORDO (Director, Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine): None of these therapies is anybody saying well, you know, once you get a single injection of bone marrow cells, you're going to - your heart will be good to go even if you've had a big heart attack. Nobody's saying that. I mean, I think these are all building blocks and our regenerative medicine strategy, that's just being formulated.
PALCA: Losordo says Murry's approach using embryonic stem cells to make new heart muscle will probably be part of that strategy. Charles Murry says his work should help convince people opposed to embryonic stem cell research that the cells really are worth studying.
Dr. MURRY: One of the arguments against embryonic stem cell research has been, well, these cells haven't ever been shown to be good for anything. And we're happy to provide an example that they can do things that at the moment, nobody's able to do with an adult stem cell.
PALCA: Although for the moment, the benefits are mostly for rats.
Joe Palca, NPR News, Washington.