Researchers at the Swedish medical university Karolinska Institutet have now shown, by measuring the radioactive isotope carbon-14 stored in cells, that heart cells are replaced throughout a person's life. The results, which are presented in the journal Science, make the replacement of cells lost during myocardial infarction a real possibility.

There is an urban myth of sorts that says that all cells in our body are replaced every seventh year. Science has shown, however, that some types of cell are renewed each week, others never; for many cell types, the rate of replacement is still a mystery. For instance, it has long been mooted whether heart cells remain the same throughout life or whether they are replaced, a debate that is of immense significance to how cardiac diseases can be treated.

Researchers at Karolinska Institutet have now shown that human heart cells undergo continual, slow replacement…