'Stemcell zoo' could save endangered species: study

Marlowe Hood AFP Yahoo News 5 Sep 11;

Scientists said Sunday they had produced the first stemcells from endangered species, a breakthrough that could potentially save dozens of animals teetering on the brink of extinction.

"The best way to manage extinction is to preserve species and habitats but that is not always working," Oliver Ryder, director of genetics at the San Diego Zoo and co-leader of the study, said in a statement.

"Stemcell technology provides some level of hope that they won't have to become extinct even though they have been completely eliminated from their habitat."

That is the case for the northern white rhinoceros, one of the first two animals included in Ryder's new "stemcell zoo."

Only seven specimens remain in existence, all in captivity and two in San Diego.

The researchers also isolated stemcells from a critically threatened primate called a drill, genetically a close cousin to humans.

In captivity, drills often suffer from diabetes, a disease scientists are seeking to treat in humans using stemcell-based therapies.

Ryder's team had already collected skin cells and other tissue samples from more than 800 species -- stored in a "Frozen Zoo" -- by 2006.

That is when he contacted Jeanne Loring, a professor at the Scripps Research Institute in nearby La Jolla and the study's other lead researcher, about the possibility of using the bank to generate and store stemcells.

At the time, scientists seeking to use stemcells to cure human disease had not yet found a reliable technique for turning normal adult cells into stemcells that can give rise to nearly any type of tissue or cell in the body.

Today, however, this process -- called induced pluripotency -- is routinely achieved by inserting certain genes into normal cells.

At first, Ryder and Loring tried to use genes from animals closely related to the target species in order to trigger the transformation, but the experiments failed.

Through trial and error, however, they discovered to their amazement that the same genes that induce pluripotency in humans also worked for the drill and the rhino.

The process in inefficient, only producing a few stemcells at a time, according to the study, published in Nature Methods. But it was still enough to start the "stemcell zoo".

Perhaps the greatest potential for helping endangered species -- beyond disease treatment -- is new reproductive stategies.

If adult stemcells can become a sperm or egg cell, for example, scientists could then use skin cells from long-dead animals in the Frozen Zoo to produce the male and female starter kit for new life.

Induced sperm cells could be combined with the eggs from living animals through in vitro fertilisation.

Alternatively, both eggs and sperm might be generated from stemcells, with the resulting embryos implanted in live host animals, a process the researchers said would likely be much more reliable that cloning techniques.

"I think that work would be a lot easier ethically with endangered species than with humans," Loring said in a statement.

"I suspect some people working in this area would love to have our cells for experiments."

Such techniques would also help boost genetic diversity by reaching beyond the small number of living individuals of a dwindling species, she explained.

Even if the remaining northern white rhinos reproduced -- which hasn't happened in many years -- the tiny gene pool could easily lead to unhealthy animals.

'Stem Cell Zoo' May Aid Endangered Species
Jennifer Welsh LiveScience.com Yahoo News 5 Sep 11;

Stem cells are quickly becoming an important tool for human medical treatments, and researchers are betting they will also be a useful tool for zoo animals. They are working to create stem cell lines from zoo animals, for use in treating animal diabetes and other ailments as well as helping the animals reproduce.

The scientists have already created a "frozen zoo," which contains different types of cells from every animal there, and now they are putting together a "stem cell zoo."

"There are only two animals in it," study researcher Inbar Friedrich Ben-Nun, of The Scripps Research Institute, said in a statement, "but we have the start of a new zoo, the stem cell zoo."

Stem cells are prized, because they can be turned into any type of cell in the body, a characteristic called pluripotency. The cells can even be turned into sperm or egg cells, and used in assisted reproduction to make more individuals of the species.

"The most important thing is to provide these stem cells as a resource for other people taking some of the next steps," said Jeanne Loring, also of The Scripps Research Institute.

Endangered stem cells

The researchers started with two species: the drill primate, a highly endangered primate genetically close to humans, and the northern white rhinoceros, which is genetically far from humans and also incredibly endangered.

To create the stem cells, the researchers used the same genes that are used to turn human cells pluripotent; they inserted those genes into the animals' skin cells. They had originally tried to use genes from the animals themselves and their close relatives, but after more than a year of trying they were having little success.

The new technique isn't very efficient yet, transforming just a few cells into stem cells at a time, but that's enough, the researchers said.

Stem cell therapies

Both animals, the researchers said, were chosen because they could benefit from stem cells now. For instance, the drill primate suffers from diabetes when in captivity, and stem cell-based treatments for diabetes being researched in humans suggest the same may work in these primates.

The rhinoceros was chosen because it is one of the most highly endangered species on the planet, with only seven animals, all in captivity, in existence (two of which are in the San Diego Zoo Safari Park). They haven't reproduced in several years, and because the population is so small there is a lack of genetic diversity, which could affect their survival.

If the researchers can use the stem cells to make sperm and eggs from skin cells of deceased animals in the frozen zoo, they could reintroduce some genetic diversity into the population, while also increasing its size.

"The best way to manage extinctions is to preserve species and their habitats," study researcher Oliver Ryder, of the San Diego Zoo, said in a statement. "But that's not working all the time."

The rhinos are a perfect example, he said, because there are so few. "Stem cell technology provides some level of hope that they won't have to become extinct even though they've been completely eliminated from their habitats."

The study was published today (Sept. 4) in the journal Nature Methods.