Scientists prove human heart can regenerate cells

LONDON, (Reuters) – Scientists said yesterday they  had shown the human body regenerates heart cells at a rate of  about one percent a year, a discovery that could one day reduce  the need for transplants.

The study of 50 volunteers, using a dating method that  detects traces of a carbon isotope left by Cold War nuclear bomb  tests, raises the prospect of artificially stimulating the  renewal process some day, they reported in the journal Science.    “It would be a way to try and help the heart to some  self-help rather than transplanting new cells,” Jonas Frisen of  Sweden’s Karolinska Institute said in a telephone interview.

“Taking advantage of the heart’s own capacity to generate  new cells either using pharmaceutical compounds or, if it is  possible, by exercise or any other environmental factor.”

Heart cells are unusual in that they stop dividing early in  life. Doctors knew there were master cells called stem cells in  the heart, but heart muscle usually simply forms scar tissue  afteer damage and never fully regenerates.

In their four-year study, Frisen and colleagues employed an  ingenious method to find out whether there is any regeneration  at all.

“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 showed that overall, the hearts of their 50  volunteers were “younger” than the patients’ ages.

Frisen said the rate at which the new cells are produced  slows as we get older, with a young adult in their twenties  renewing cells at a rate of about 1 percent a year, falling to  half a percent a year by the age of 75.

“If you exchange cells at this rate it means that even if  you live a very long life you will not have exchanged more than  50 percent of your cells,” said Frisen. “So at any given time your heart is a mosaic of cells you  carry with you from birth and cells that that have been added  later to replace cells that have been lost during life.”

The finding could also help scientists determine whether  some people are predisposed to heart disease, by looking at the  heart’s ability to renew cells.

“We are interested in studying whether some heart diseases  could potentially be caused by too low an ability to replace  heart cells,” Frisen added.