Tuesday, April 21, 2015

Can UGA scientists save endangered big cats with a “frozen zoo”?

Donors to a stem cell bank include a Sumatran tiger and clouded leopard from Zoo Atlanta 

Mary Jo DiLonardo
Jalal, the Zoo Atlanta tiger that contributed cells to the project
Jalal, the Zoo Atlanta tiger that contributed cells to the project
Photograph courtesy of Zoo Atlanta
It’s a long way from the jungles of Sumatra to a lab in Athens, Georgia, but two University of Georgia researchers hope to create a stem cell bank that could save endangered big cats. Its first deposits are cells collected from Zoo Atlanta’s Jalal, a Sumatran tiger, and Moby, a clouded leopard. Franklin West, assistant professor of regenerative medicine, and Steven Stice, director of UGA’s Regenerative Bioscience Center, teamed to create the stem cell bank and crowdsource funding. We talked to West about their planned “frozen zoo.”

How did you get into stem cell work?
I started with human embryonic stem cells and turned them into sperm. I always get the question, “Isn’t there already enough sperm in the world?” But there is so much infertility. Turning stem cells into sperm allows you to study every single stage of sperm development.

What made you decide on tigers and leopards?
We could use stem cell technology with a lot of species. But the problem is, when you start trying to save elephants, we don’t know a lot about their reproductive biology like we do with big cats, because we all have cats as pets. We chose the Sumatran tiger because it’s highly endangered; there are only 400 left. There are so few individuals that relatives are starting to breed with one another, leading to genetic problems in cubs. The clouded leopard is not endangered but threatened.

How does it work?
We take skin cells when the animals are sedated. We are able to generate stem cells from those skin cells and then turn the stem cells into sperm and eggs, which can be fertilized. From there, we can put that embryo into a recipient animal—like a domestic cat that thinks it’s pregnant with its own offspring.

What are the possible implications?
Theoretically you could make thousands of embryos and transfer them to thousands of cats, and the species could be doing fairly well within a couple of years. It could literally go from critically endangered to being off the endangered species list altogether. It would be huge.
A big problem in zoos is that they’ll have only four or five animals of a species. When the population is small and you have limited genetic diversity, you have health problems when you start breeding.
Stem cells are immortal; the embryos would essentially live forever. You could create what we could call a frozen zoo. They are already doing this for seeds, like some species of corn that are resistant to drought. You basically have an insurance policy against extinction that could be caused by natural or man-made catastrophes like global warming.

Why crowdsource through Georgia­Funder instead of soliciting research grants?
There’s really not a good funding mechanism for this kind of endangered species conservation work. So this is a grassroots effort. I feel like enough people out there really think it’s important. If we get the word out about what we can do to save endangered species, then people will pitch in.

Tiger theory
How do you go from tiny cells to big cats? Franklin West walked us through the theoretical process.
  • Two Sumatran tiger (male and female) skin cell biopsies turn into 10,000 skin cells
  • Which are reprogrammed into 5,000 stem cells
  • Which are developed into 10,000 sperm and 10,000 eggs
  • Which form 10,000 embryos after fertilization
  • Which are transferred into 1,000 female cats
  • And develop into 10,000 kittens, which change the face of an entire species on the brink of extinction.

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