April 3, 2009
Study: Human Heart Cells Regenerate During Lifetime
Researchers have used the amount of carbon 14 in the atmosphere from nuclear testing in the 1950s and 1960s to determine that human heart cells continue to regenerate into adulthood.
About 50 percent of heart cells a human is born with will regenerate during their lifetime, scientists reported in the journal Science.
The new finding could suggest that doctors could one day be able to artificially stimulate heart cell renewal in patients who have suffered myocardial damage from a heart attack, which typically results in chronic heart failure.
"The loss of heart cells after, say, a heart attack often leads to impaired cardiac function," said Professor Jonas Fris©n, of Karolinska Institute. "This new finding that heart cells can be replaced motivates further research into ways of stimulating the renewal mechanism to replace the cells that have been lost."
Lawrence Livermore National Laboratory scientist Bruce Buchholz with colleagues from the Karolinska Institute, Universit© Claude Bernard Lyon, Lund University and Lund University Hospital used the Laboratory's Center for Accelerator Mass Spectrometry to measure the amount of carbon 14 in DNA in order to establish the age of cardiac muscle cells in humans.
These levels of carbon 14 in the atmosphere remained somewhat stable until the Cold War, when above-ground nuclear bomb tests caused levels to jump before slowly decreasing following the end of testing in 1963.
"Because DNA is stable after a cell has gone through its last cell division, the concentration of carbon 14 in DNA serves as a date mark for when a cell was born and can be used to date cells in humans," researchers found.
"The DNA of all plant and animal cells incorporated high concentrations of carbon-14 released into the atmosphere by above-ground nuclear testing during the Cold War, and this unfortunate episode provides a unique opportunity to test cell population dynamics in human tissues,"
Charles Murry of the University of Washington and Richard Lee of Harvard Medical School wrote in a commentary.
Carbon-14 dating revealed that the hearts of 50 study participants were "younger than their ages, researchers told Reuters.
"By analyzing individuals born at different times before 1955, it is possible to establish the age up to which DNA synthesis occurs, or whether it continues beyond that age," Buchholz said.
By age 25, renewal of heart cells gradually decrease from 1 percent turning over annually to .45 percent by the age of 75, researchers said.
"DNA of myocardial cells is synthesized many years after birth, indicating that cells in the human heart do, in fact, renew into adulthood," Buchholz said. "At the age of 50, 55 percent of the heart's cells remain from the time around birth and 45 percent have been generated later."
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