Dolly’s Cloned Relatives in Good Health

Besides the four Dolly clones, nine other cloned sheep from three different cell lines were included in the study, giving a total of 13 sheep between seven and nine years old (making them senior citizens in human years). The first sheep to be cloned might have died prematurely, but her genetically identical successors are still sprightly in old age, scientists have said.

Professor Kevin Sinclair, who led the research, said: “One of the concerns in the early days was that cloned offspring were ageing prematurely and Dolly was diagnosed with osteoarthritis at the age of around five, so clearly this was a relevant area to investigate”.

While no animals were lame, there were signs of mild osteoarthritis in some sheep and one had moderate disease, which scientists said was to be expected at their age. Twenty years after Dolly’s birth, SCNT has been used to clone more than 20 mammalian species, including human cells.

In the new study, 13 cloned sheep underwent a series of health tests, including tests of their blood glucose levels, blood pressure, body fat composition and walking ability.

“We found that or clones, considering their age, were at the time of our research healthy”. These embryos give rise to viable offspring that age normally.

The four sheep, which were derived from the same batch of cells as Dolly and could be considered her clone “sisters”, have just reached their 9th birthday, which is equivalent to age 70 in human years, researchers who have been studying the sheep said.

Dolly, born on July 5, 1996, was produced by a cloning technique known as somatic-cell nuclear transfer.

The research was carried out under the authority of the United Kingdom Animal (Scientific Procedures) Act 1986 with approval from The University of Nottingham Animal Welfare and Ethical Review Board.

To date, cloned cells are not in routine clinical use. So-called induced pluripotent stem cells, or iPS cells, can be made directly from adult skin cells by reprogramming them. However, it’s still inefficient, and many embryos cloned using SCNT don’t survive until birth or long afterward.

RG: What are the next steps in this research? .

To detect subtle signs of aging, the scientists conducted a battery of tests to check for symptoms of heart disease, Type 2 diabetes and osteoarthritis.

“Our detailed study and less detailed studies by others suggest that once cloned animals get past the first month or two of life they are healthy”. It wasn’t clear whether Dolly’s problems were because she was a clone.

Sinclair: I believe that there have now been 23 species cloned – some quite routinely – including cattle in North America and companion animals in Korea.

The findings open up possibilities for further cloning research. Many blamed cloning when mature animals appeared to show signs of early aging. The animals also underwent X-rays and MRIs to assess their bone and muscle health.

Animal cloning is used in agriculture, mainly to create breeding stock, as well as in the business of “bringing back” people’s dead pets. They should be just as healthy as any other animal that’s conceived naturally.

“Overall the results are suggesting that these animals are remarkably healthy”.

Cloning won’t be truly safe until embryos survive at rates similar to those produced through natural conception or in vitro fertilization.