Premature Aging Not Found in Cells of Cloned Mice

The cells of cloned mice show no signs of premature aging, despite being copied through six generations, according to a study in today’s Nature. In fact, some of the cells showed signs of getting younger. The results contradict a 1999 study of Dolly the cloned sheep, which suggested that the protective tips of her chromosomes, known as telomeres, were showing signs of early wear and tear because they had been copied from genetic material that was 6 years old.

Some researchers have feared that cloned animals might die prematurely or that healthy cloned cells created as medical treatments might die off before they could fight disease. Researchers from the University of Hawaii and Rockefeller University found, however, that the telomeres of some cloned mice were longer than expected, even in mice that lived for more than one year.

--Compiled by Times medical writer Thomas H. Maugh II