Stem cells from rhino skin

Northern White Rhinoceros; Photo credit: San Diego Zoo

What are those rhinos doing in a stem cell blog? Researchers at Scripps Research Institute have converted skin cells from those rhinos (or their San Diego zoo-mates) into reprogrammed stem cells. The team also created stem cells out of skin samples from a primate called a drill.

Both projects came out of conversation between Oliver Ryder, the director of genetics at the San Diego Zoo Institute for Conservation Research, and Jeanne Loring, professor of developmental neurobiology at Scripps Research and CIRM grantee. Ryder’s team had already established the Frozen Zoo, a bank of skin cells and other materials from more than 800 species and wondered if the thousands of samples they had amassed might be used as starting points.

The group, which includes an intern from the CIRM Bridges to Stem Cell Research program, published their work in the September 4, 2011 advanced online edition of Nature Methods. According to a Scripps press release, the work has the potential of preserving and even strengthening populations of endangered animals.

One of the greatest concerns with small populations such as the northern white rhinos is that even if they did reproduce, which hasn’t happened in many years, their genetic diversity is inevitably and dangerously low, and such inbreeding leads to unhealthy animals.

But researchers are moving toward inducing stem cells to differentiate into sperm or egg cells. With that accomplished, one possibility is that scientists could take skin cells in the Frozen Zoo from long dead animals, induce pluripotency, trigger differentiation into sperm cells, and then combine these with a living animal’s eggs through in vitro fertilization. Otherwise-lost genetic diversity would then be reintroduced into the population, making it healthier, larger, and more robust.

Or, both eggs and sperm might be produced from the stem cells, with the resulting embryos implanted in live animals, a process that current research suggests could be much more reliable than existing cloning techniques.

Scientists are already exploring the possibility of producing sperm and eggs from stem cells as a potential solution to human infertility issues. Loring hopes that some of these groups might consider initial technique development using endangered species stem cells. “I think that work would be a lot easier ethically with endangered species than with humans,” she said, “so I suspect some people working in this area would love to have our cells for experiments.”

The press release goes on to quote Ryder:

“The best way to manage extinctions is to preserve species and their habitats, 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. I think that if humankind wants to save this species, we’re going to have to develop new methodologies.”

CIRM funding: Susanne Montague (TB1-01186)

- A. A.