Study: Cloned animals don’t age any faster
Dolly the sheep, the world’s first clone of an adult animal, died in middle age. But a new study makes the case that the extraordinary circumstances of her birth did not play a role in her untimely death.
After examining more than a dozen cloned sheep old enough to be considered senior citizens — including four clones of the same ewe as Dolly — researchers concluded that they weren’t growing old any faster than sheep born through more conventional means. The results were published Tuesday in the journal Nature Communications.
“There was no evidence to suggest that these animals were aging abnormally or prematurely,” study leader Kevin Sinclair, a developmental biologist at the University of Nottingham, said in a video. “They were aging in a perfect, healthy manner.”
Sinclair and his colleagues aren’t interested in making carbon copies of sheep or other livestock. But they do want to know whether the technology used to create clones is safe, since they could be used to develop treatments for a variety of medical conditions.
Clones like Dolly are made by taking an egg, removing its nuclear DNA — the part that contains the vast majority of an animal’s genes — and substituting the DNA from another animal. If all goes well, that egg will mature into an embryo that is a genetic twin of its DNA donor.
Scientists could use that embryo to create stem cells for regenerative medicine. Or, as in the case of the 13 sheep in this study, they could be transferred to a uterus and carried until birth.
Cloning technology has improved in the 20 years since Dolly’s birth, but it’s still pretty inefficient, Sinclair said. Cloned embryos often fail to implant in a uterus. Even if they do, they often fail to develop to term. If there is a live birth, the odds of death in the first few days or weeks are higher than for other animals.