The first rhino embryos have been created in a test tube and could help save the northern white rhino, which is essentially extinct.
There are just two northern white rhino (NWR) females left alive. The last male, called Sudan, died in March in Kenya, meaning the subspecies is doomed to die out unless the new IVF techniques bear fruit.
There are 21,000 southern white rhinos (SWR) and these will be used as surrogate mothers. The scientists are planning for the the first NWR calf to be born within three years.
Very few frozen NWR eggs exist, so the scientists started by fertilising SWR eggs with stored NWR sperm to create hybrid embryos and to show the technique works. A critical next step is to take eggs from the last two NWR females and produce pure NWR embryos.
But even if the implantation of the pure NWR embryos does lead to the birth of healthy calves in future, the NWR faces another huge challenge: the lack of genetic diversity needed to build up a healthy population.
There are a dozen samples of skin from different NWR and these are being kept alive in cell culture. Stem cell technology may be able to turn these cells into eggs and sperm which could be used to create genetically diverse embryos, although this is likely to take a decade. The scientists have already succeeded in creating rhino stem cells from SWR embryos.
“These are the first in-vitro produced rhinoceros embryos ever,” said Professor Thomas Hildebrandt, at the Leibniz Institute for Zoo and Wildlife Research in Berlin, Germany, and who led the work published in the journal Nature Communications. “They have a very high chance to establish a pregnancy once implanted into a surrogate [SWR] mother.”
The project was first conceived in 2008 when it became clear that the NWR’s days were numbered, due to poaching for its horn, civil war and the destruction of wild habitat which saw numbers plunge from 2000 in the 1960s to the last two today. The NWR can reproduce in zoos, but only very slowly.
“We now see clearly a moral obligation not only to help the NWR to somehow survive in captivity, but later even help them get back to their original range and be wild again,” said Jan Stejskal, at the Safari Park Dvů r Králové in the Czech Republic and also part of the research team.
The team hope to be granted permits to take eggs from the last two NWR females by the Kenyan authorities in the coming months. Eggs taken from even elderly or infertile SWR have successfully produced embryos. But the procedure, which requires a long device to be inserted in the rectum, is risky as the rhinos must be put under general anaesthetic for two hours.
“We are highly afraid that something unexpected may happen during this procedure which is related to the heart or something else – that would be a nightmare,” said Hildebrandt. “But we are extremely confident we can get the [eggs] out.”
Using IVF techniques to save species from extinction has been talked about since the 1970s, when the methods began to be used in humans and livestock. But to date, there has been little success and even the simpler technique of artificial insemination has only really helped three endangered mammals: the giant panda, Asian elephant and black-footed ferret.
“Impressive results in a Petri dish don’t easily translate into a herd of healthy offspring,” warned Terri Roth and William Swanson, both at Cincinnati Zoo in the US and authors of a commentary in Nature Communications on the new research.
They said IVF technologies are seen as the last hope for some species and can be a powerful conservation tool, but only if accompanied by strong and enforced legal protections for the wild animals. “For decades, debate has raged over protecting wild populations versus establishing managed breeding programs when it should not be an either/or ultimatum; both efforts should be undertaken.”