A modern-day “ark” that holds tissues from endangered animals should be built as an insurance policy to save species from extinction, Sir Ian Wilmut, the creator of Dolly the Sheep, has said.
A biobank that preserves sperm, eggs and other material from at-risk animals would ensure that scientists had the biological tissues at hand to resurrect extinct creatures once the means to do so exists, the Edinburgh researcher said.
The store of cells and tissues could provide the same reassurance for animal diversity that the Svalbard Global Seed Vault intends for crops. The Svalbard facility is built into an Arctic mountainside and holds seeds from the world’s most prized crop plants. The intention is to use the seeds, should common crop species ever be wiped out.
“The absolute minimum we should do is preserve tissues from these animals in such a way they can be thawed and grown again,” Wilmut told reporters before the 20th anniversary of Dolly’s birth on 5 July 1996.
He explained how a biobank of cells taken from rare animals, such as tigers and elephants, could help ensure their survival. If eggs and sperm from endangered species were preserved, they could be used to make viable embryos. But major advances in biology would still be needed to bring them back from the dead, because the surrogate female animal would be likely to belong to another species.
The store could help to save endangered species even without using the tissues to make fresh embryos. Another option is to look at how the genome of an endangered or extinct species’ differs from that of a more abundant animal. Once the differences are fully known, it may be possible to gradually turn the more common species into the endangered one, by making incremental changes to the genome of the abundant animal over several generations.
When Dolly the Sheep was born at the Roslin Institute in Edinburgh, many in the scientific community considered the feat impossible. From more than 250 embryos that survived the cloning manipulation, only Dolly, made from an adult sheep’s mammary cell, went on to a successful birth. The animal was put down in 2003 after she developed a progressive lung disease.
Wilmut said that without Dolly, stem cell research might be 20 years behind where it is today. But despite the rapid progress scientists have made in the field, notably in working out how to turn one cell type into another, he warned that cell-based therapies were still many decades way.
In one major trial planned for 2018, researchers will take cells from patients with Parkinson’s disease and turn them into fresh brain cells. The cells will then be injected into their brains, in the hope that the new neurons churn out dopamine, the brain chemical that is lost in Parkinson’s disease.
The phase-one trial is a necessary first step that is needed to understand whether the treatment is safe. But Wilmut said that merely proving such cell therapies are harmless could take 20 years. That work must be done before larger trials can look at the therapy’s effectiveness.
Wilmut admitted that he had been “over-enthusiastic” about the speed at which stem cell therapies would help patients. “If you’re in research work you’re an optimist, you have to be,” he said. “Sometimes natural optimism makes us be too hopeful about what can be achieved. I think perhaps we are slowly learning to be more realistic and not make the same mistake again.”
He said it was unrealistic to think that patients would have personalised cells made to repair and treat them in the future, because the number of people with medical conditions was so large. Instead, he said scientists should press on with making a “library” of cells that are compatible with the immune systems of 90% of the population. “In a few decades there might be a cell line that’s suitable for every person in the world,” he said.
In the past five years, laboratories around the world have witnessed the rapid rise of a procedure called genome editing. The technology, which gives scientists the ability to make precision changes to the DNA code, has sparked a global debate over the acceptability of altering the genetic makeup of human embryos. While the procedure could potentially prevent children from inheriting devastating diseases, the idea is highly controversial because any genetic changes, and harms they introduce, would be passed on to future generations.
But Wilmut said we should not dismiss the idea of modifying human embryos, to prevent disease or even enhance future humans. “I think as a principle there shouldn’t be a simple red line that says ‘no we don’t’. The question is what’s the benefit, what’s the risk of mishap and does the one thing justify the other?” he said. “If there’s a procedure that would enable you to either correct a disease or enhance somebody in some way, and approved within a broad context, then I would be in favour of it.”