bing

 youtube

Dolly the sheeps skeleton shows no signs of abnormal osteoarthritis

Date (2017-11-24)

Dolly the sheep may have died young, but at least she didn't suffer severe early-onset osteoarthritis, UK researchers say.

Key points:

  • Dolly the sheep was the first mammal cloned from an adult cell
  • She was euthanased at six years of age amid fears of age-related disorders, including osteoarthritis
  • Three experts independently examined leg bone radiographs, or X-rays, from Dolly and three other sheep
  • Dolly had no more radiographic osteoarthritis than sheep of comparable age

For those who don't remember, Dolly made history and global headlines as the first mammal to be cloned from an adult cell.

She was born in 1996 and lived six and a half years before being put to sleep in 2003 amid concerns that she was suffering age-related diseases.

In a new study, vets examined X-rays of the famous sheep's bones and found she had a few signs of early-onset osteoarthritis, but no more than a naturally conceived sheep of comparable age.

The work, published in Scientific Reports on Thursday, could help allay fears about cloning stem cells for stem cell therapy, which uses the same technology used to clone Dolly, according to Chris Little, a bone and joint disease researcher at the University of Sydney.

"Maybe this idea of cloning cells to treat disease doesn't have some of the risks that were first thought of when initial reports about Dolly's osteoarthritis surfaced," Professor Little said.

Concerns about cloning 'unfounded'

Some scientists had worried that because the genetic material used to clone Dolly came from an adult sheep, she had a head start on ageing.

In 2001, Dolly started walking stiffly and was diagnosed with osteoarthritis and given anti-inflammatories.

Yet no formal assessment for osteoarthritis was done, said Kevin Sinclair, developmental biologist at the University of Nottingham and co-author of the study.

"We therefore felt it necessary to put the record straight."

There was a problem: none of Dolly's X-rays were preserved. So in the absence of original records, Professor Sinclair and his colleagues went to the next best thing: Dolly's skeleton.

She may have died 15 years ago, but Dolly's remains are kept in Scotland. So the researchers borrowed her limb bones and X-rayed them to look for signs of osteoarthritis.

They also X-rayed bones from Bonnie, Dolly's daughter, and Megan and Morag, sheep that were cloned from embryonic lamb cells.

The X-rays were independently scored by three orthopaedic vets for signs of osteoarthritis, such as bone spurs.

Megan and Bonnie, who were 13 nearly 10 years old respectively when they died, scored highest. This was no surprise; the single biggest risk factor for osteoarthritis in sheep, and humans, is ageing, Professor Little said.

Morag, the youngest and a clone of Megan, had almost none.

Dolly had some signs of osteoarthritis, particularly in a knee and elbow, but no more than expected in a six-year-old sheep.

The work adds to a study published last year by the same group, which found 13 cloned sheep, including four eight-year-old Dolly clones, were free of degenerative joint disease apart from mild, or in one case moderate, osteoarthritis.

"Concerns over a direct link between Dolly's osteoarthritis and cloning were unfounded," the researchers wrote.

Clinical versus radiographic osteoarthritis

The excitement about Dolly and cloning technology shouldn't be clouded by the perceived risk of osteoarthritis, Professor Little said.

"What they have done and the conclusions they draw from their data make sense to me," he said.

It's important to make the distinction between clinical and radiographic osteoarthritis, Professor Little added.

"You will have clinical [osteoarthritis] if you have all of the following: pain in your joints on most days of the last month and radiographic change", which is when signs of joint damage, such as bone spurs, show up on X-rays or MRI.

Radiographic osteoarthritis occurs when imaging shows joint changes but the patient feels no pain.

Most people over the age of 70 have radiographic osteoarthritis in at least one joint, but the correlation between clinical and radiographic osteoarthritis is "really poor", Professor Little said.

"You can have a horrible X-ray and the joint has never hurt you a day in your life."

That Dolly was lame shows she was probably in pain, but whether it was due to mild radiographic osteoarthritis or something else is up for debate.

There could have been any number of reasons such as foot pain, which is quite common in sheep, Professor Little said.

source:abc.net.au

FREE ONLINE CONSULTATION