Nuclear Fallout Solves Heart Mystery
Can the atomic bomb tests of the Cold War lead to better treatments for heart attacks? Well, it's a bit of a stretch, but the answer may be yes.
Medical dogma says if you damage your heart muscle, either from injury or heart attack, those muscle cells will never grow back. The damage is permanent. But now a team of scientists in Sweden has shown that heart muscle cells do regenerate — just very, very slowly. And the researchers used fallout from the Cold War atomic bomb tests to prove it.
Atomic Fallout Stored In DNA
Ratan Bhardwaj and his colleagues at the Karolinska Institute in Stockholm studied carbon 14 levels in the DNA of heart muscle cells collected from cadaver tissue.
"The atomic bombs liberated a demonstrable amount of C14, which we could actually trace and see how old that cell is based on that," says Bhardwaj.
Heart Muscle Cells Regenerate — But Slowly
Using that data, Bhardwaj and his colleagues not only discovered that heart cells do replace themselves, but they also determined the regeneration rate.
The turnover rate isn't very fast: about a 1 percent turnover rate in a 20-year-old. "But the amazing thing is that level isn't zero, and that's what we didn't understand before," says Bhardwaj.
"The longstanding view is that the heart is one of the least regenerative organs in the body," says Chuck Murry, a stem cell biologist at the University of Washington. Murry says the new results don't really change that, but they do suggest some regrowth is possible.
A Better Heart Attack Treatment
Murry says there are two main implications from this research, which was published in the journal, Science. "The first is that heart muscle cells are very long lived, and difficult to replace and you're going to die with most of the cells you were born with, so you'd better take good care of them," he says.
"The second thing is the more optimistic note, since there is a little bit of turnover, if we can figure out how this works, we can exploit it therapeutically."
In other words, coax the heart into repairing itself after a heart attack or trauma.
That would be an unexpected bit of good news inspired by the Cold War atomic tests.
9(MDAyNzUwMDI2MDEyNTA3MTU5NzcyNTQyNA004))
MICHELE NORRIS, host:
Medical dogma says if you damage your heart muscle, either from injury or heart attack, those muscle cells will never grow back. Now a team of scientists in Sweden has shown that they do regenerate, just very, very slowly. The team reached its conclusions thanks to above-ground atomic bomb tests carried out during the Cold War. NPR's Joe Palca explains.
JOE PALCA: Okay, here's how it works. Ratan Bhardwaj is a physician and scientist who went to work at the Karolinska Institute in Stockholm.
Dr. RATAN BHARDWAJ (Karolinska Institute): We had this common idea of asking a very crazy question of - could we possibly date old cells?
PALCA: That is, tell when the cell first came to be. Now, there are some cells in your body that you've had since you were a baby, but others are constantly turning over. Your outer layer of skin cells have only been around for a matter of days or weeks. But cells don't have dates stamped on them when they're born, so Bhardwaj and his colleagues had to come up with another way of dating them, and then they thought of the above-ground atomic bomb tests in the Cold War.
Dr. BHARDWAJ: The atomic bombs liberated a demonstrable amount of C14, which we could actually trace and figure out how old that cell is based on that.
PALCA: C14 is a radioactive form of carbon. This stuff spread all over the planet and got into everything, including people. Not enough to make them sick, but enough to detect in their cells.
So the atomic bomb tests provided the date stamp Bhardwaj needed. Even after the tests ended, there was more Carbon 14 around than before the tests, so there was a Carbon 14 date stamp even for people born in the 1980s, just a smaller one.
As they report in the journal Science, when Bhardwaj and his colleagues used Carbon 14 levels to see how many heart muscle cells were turning over, to their surprise they saw there were some - not a lot, but some.
Dr. BHARDWAJ: Only about a percent turnover in a 20-year-old, but the amazing thing is that that level isn't zero, and that's precisely what we didn't understand before.
PALCA: The rate actually goes down to about a third of a percent for people in their 70s, but Bhardwaj says the point is, it's not zero.
Dr. CHUCK MURRY (University of Washington): The longstanding view has been that the heart is one of the least regenerative organs in the body.
PALCA: Chuck Murry is a stem cell biologist at the University of Washington in Seattle. There are three classes of cells in the heart: the ones that make up blood vessels, the ones that make up connective tissue, and the ones that make up the heart muscle. Murry says the blood vessels and connective tissue clearly regenerate.
Dr. MURRY: And the big debate really has been whether there is any turnover of the muscle cells.
PALCA: Murry says the new research proves there is, and he says there are two main implications from this research.
Dr. MURRY: The first is that your heart muscle cells are very long-lived and that you're going to probably die with most of the cells that you were born with. So you'd better take good care of them.
PALCA: You know what he means: eat the right foods, get exercise, etcetera, etcetera.
Dr. MURRY: The second thing is the more optimistic note, which is since there is a little bit of turnover, if we can figure out how this works, we can exploit it therapeutically.
PALCA: In other words, find some way to coax the heart into repairing itself after a heart attack or trauma. That would be an unexpected bit of good news inspired by the Cold War atomic tests.
Joe Palca, NPR News, Washington. Transcript provided by NPR, Copyright National Public Radio.
