"Telomeres, Cellular Immortality,
and Cloning:
Opportunities and Challenges"
Results announced last Spring show that six cloned cows show signs of being younger than their chronological ages. The cloning method, developed at Advanced Cell Technology Inc. (ACT), appears to have reversed the aging process of cells, opening the door to creating organs that are nearly immortal for use in transplants. Virtually all types of body cells, except reproductive cells, contain this aging clock. It consists of a strand of DNA on the end of all chromosomes. These ends are called telomeres and every time a cell divides some of this tail is used up. We thus eventually run out the aging clock until the cells in our bodies stop dividing. The cloned animals, one of which is celebrated her first birthday in April, have telomeres that look like newborn calves despite the fact that they were cloned from senescent cells. The cloning technique may also allow scientists to create tissue lines to treat disorders ranging from Parkinson's and Alzheimer's to diabetes and heart disease. Cloning could also supply a crop of youthful cells to increase the breeding years of farm animals. Nevertheless, researchers still do not know exactly how cloning helps cells shrug off the signs of aging, or whether this actually translates into a longer lifespan for the animals themselves.