Scientists at Stockholm’s Karolinska Institute have proved that the human heart produces new muscle cells throughout normal adult life, raising hope that this regenerative prowess can be harnessed to replace cardiac tissue that had been damaged by heart attacks and other pathological conditions.
Conventional wisdom had been that the heart does not produce new cells and people died with pretty much the same ticker as the one they started out with.
But Jonas Frisen and colleagues determined that up to age 25, the heart replaces about 1% of its cells per year, and it continues doing so, albeit at gradually diminishing rates, through old age.
When it’s all said and done, nearly half the heart’s muscle cells are created during a normal lifetime, the scientists estimated.
The scientists knew that cell turnover rates could be quantified in animals by adding radioactive molecules to cells and observing how quickly the radioactivity disappears.
This can’t be done in humans for ethical reasons, but Frisen reasoned that above-ground nuclear weapons testing, which was done by several countries until 1963, had seeded the atmosphere with carbon-14, and this stuff would find its way into the food chain.
The net result would be that the DNA in the nuclei of all living creatures has been C-14 labeled more or less continually as a byproduct of the nuclear folly.
The C-14 remains in the cell for as long as it survives, but since C-14 levels have diminished since 1963, cellular loads of the stuff in more recently formed cells have also diminished. The amount of C-14 in a particular cell thus indicates when it was formed.
The clever work appears in Science.
Loren Field, a cardiologist at Indiana University, told the New York Times the goal now becomes “to try to tickle the system to enhance (cellular regeneration rates).”