Washington D.C.-- Cells from six healthy cow clones show no signs of the premature aging reported for Dolly the cloned sheep, researchers say in the 28 April issue of Science. In fact, the cloning process seems to have sent the cow cells into a backwards time warp, making them appear even younger than cells from normal cows of the same age.
Robert P. Lanza of Advanced Cell Technologies of Worcester, Massachusetts and his co-authors on the Science paper say that they still don't know exactly how cloning helps these cells shrug off the signs of aging, or whether this translates into a longer lifespan for the animals themselves. Despite these unsolved mysteries, the finding erases a lingering doubt about the utility of cloned cells by demonstrating that the process doesn't automatically rob cells of a normal lifespan. In fact, say Lanza and colleagues, cloning could supply a crop of youthful cells for a variety of uses, from medical applications like designing and transplanting replacement tissues for the human body to increasing the breeding years of farm animals.
Like the nine lives of a cat, cells possess a finite number of division cycles--a cell's life is at an end when it can no longer divide. To create the cow clones, the researchers used cells that were near the end of this lifespan, with only a few bouts of cell division left. Surprisingly, Lanza and the others discovered that the cloning process seemed to restore the "nine lives" of these cells in the six cows. Instead of being zero to four division cycles away from the end of their lives, cells taken from the cows were more than 90 cycles away from their end.
Cells also betray their age through the wear and tear on their telomeres, the
Contact: Heather Singmaster
American Association for the Advancement of Science