The northern white rhinoceros is nearly extinct. The last vestiges of the subspecies are just three individuals living at a wildlife conservancy in Kenya.
Until now, there was little hope that the remaining rhinos would ever reproduce. The male, Sudan, is 42 years old and has a low sperm count; his 26-year-old daughter Najin has a leg injury that would not allow her to bear the weight of pregnancy; and her daughter, Fatu, has a uterine disorder that prevents her from becoming pregnant.
However, a team of scientists says the subspecies might still have a chance—with the help of stem cells and in-vitro fertilization (IVF). Their rhino rescue plan is outlined in an article published in the journal Zoo Biology.
"The attempt to save the northern white rhinoceros requires new technologies, new approaches and solutions to prevent the imminent extinction," Joseph Saragusty, an andrologist at the Leibniz Institute for Zoo and Wildlife Research in Berlin and first author of the rescue plan, said in a press release.
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The first step of the plan would be to obtain egg and sperm cells. The two remaining females are the only natural sources of eggs—and such limited genetic diversity would be insufficient to save the species from extinction.
So the team turned to the idea of artificially producing eggs and sperm. It is possible to create sperm from embryonic stem cells. But because northern white rhino embryonic stem cells are hard to come by, the team is instead focusing on a more recent technology, which allows almost any cell type (e.g. skin cells) to be reprogrammed into embryonic stem cells. They note that reprogrammed cells have proven capable of generating eggs and sperm in mice.
By reprograming cells, the researchers could increase genetic diversity in the future population, as cells from 12 other rhinos are currently in frozen storage.
Next, a surrogate would be needed, and the researchers have identified the southern white rhino as the ideal choice. Populations of this southern subspecies are flourishing, thanks to recent successful conservation efforts.
No one has ever successfully completed IVF on a rhino of any species.
Raising funding for the project is sure to be a challenge. According to the researchers, they would need millions of dollars to create a rhino using IVF.
“The northern white rhinoceros will go extinct if we don’t do this,” Oliver Ryder, a conservation geneticist at San Diego Zoo Global and a leading architect of the rescue plan, told Scientific American.
However, some conservation biologists, such as Stuart Pimm at Duke University, have expressed concern. “This says we can let species go to the very brink of extinction and modern technology can bring them back,” he said. “There is a very substantial moral hazard in that.”
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