It's been 20 years since research that gave birth to Dolly the sheep began. Just three weeks after the scientific world celebrated such a feat, researchers from The University of Nottingham released their own study of sheep from the same cell line as Dolly, saying that it's possible for cloned animals to live long and healthy lives.

Called Daisy, Dianna, Denise and Debbie, the Nottingham Dollies are now 9 years old and are part of a flock of cloned sheep cared for by Kevin Sinclair, a developmental biology expert from the university's School of Biosciences. They were cloned from the same mammary gland cell line as Dolly while the other clones were from fetal fibroblasts.

Published in the journal Nature Communications, Sinclair and colleagues' study is the first to detail a comprehensive assessment of non-communicable diseases related to age in cloned animals. At 7 to 9 years old, the Nottingham Dollies and the rest of their flock are 60 to 70 years old in human years. And at that age, the cloned sheep were shown to exhibit no long-term detrimental effects to their health.

Dolly, the Nottingham Dollies and others part of the study were cloned from adult cells using a method called somatic-cell nuclear transfer (SCNT). In fact, Daisy, Dianna, Denise, Debbie and their flock were the result of a study seeking to improve SCNT efficiency. However, healthy aging in animals cloned through SCNT has long been a concern but the problem was never properly investigated before.

"One of the concerns in the early days was that cloned offspring were ageing prematurely," explained Sinclair.

Since Dolly was diagnosed at 5 years old with osteoarthritis, the researchers saw that the area was relevant enough to investigate. They checked the flock of cloned sheep for insulin sensitivity and glucose tolerance and assessed blood pressure levels and musculoskeletal condition and found that the subjects were healthy despite their advanced age. Some of the animals did show mild osteoarthritis (moderate in Debbie's case) but none require treatment.

Earlier in July, Ian Wilmut, one of the researchers part of the team that gave life to Dolly, suggested that endangered animals be cloned to prevent certain species from going extinct. Revolutionizing conservation efforts, he said that a biological bank containing eggs, sperm cells and tissues of various animals should be developed.

Aside from in vitro fertilization, the contents of the biobank may also be used to map the genomes of extinct or endangered animals and genetically engineer thriving species to carry the genetic information of the endangered animals.

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