Viable embryos from the world’s last remaining northern white rhinos are set to be implanted into surrogates using in vitro fertilization soon, in an exciting development to save the species from extinction.
The plight of the world’s last northern white rhinos is well known. Sudan, the last male, died in March 2018, leaving mother and daughter Najin and Fatu as the world’s only remaining members of their species. An audacious plan was concocted to save the rhinos from extinction, by harvesting eggs from the two females and artificially inseminating them using frozen sperm from deceased males to create northern white rhino embryos.
This was successfully carried out in August 2019 with two viable northern white rhino embryos created, followed up by a third in December 2019. Now, an international team from Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW), Safari Park Dvůr Králové, Kenya Wildlife Service, and Ol Pejeta Conservancy – where Najin and Fatu are housed – have announced they have successful created two more viable embryos, taking the number of pure-breed northern white rhino embryos up to five. This means the next step is finding suitable southern white rhino surrogates to try and carry them to term.
This is a hugely exciting step in the plan to save the rhinos from extinction. Northern white rhinos are a subspecies of white rhinoceros (the other being southern white rhinos) and were once found across several East and Central African countries. Years of widespread poaching and civil war in their home range devastated their populations, and they are now considered functionally extinct. Najin and Fatu belong to the Safari Park Dvůr Králové in the Czech Republic but are housed at the Ol Pejeta Conservancy in Kenya, where they are two of the best-guarded animals in the world.
The first three viable embryos were created by harvesting oocytes – immature egg cells – from Najin and Fatu in 2019, and artificially inseminating them using frozen sperm from the last two males: Suni, who died in 2014, and Sudan. Plans to collect more oocytes had to be put on hold last year due to the pandemic. However, in mid-December 2020, another oocyte collection was carried out. The cells were immediately rushed from Kenya to the Avantea Laboratory in Italy, fertilized with the semen of Suni, and were cryopreserved on Christmas Eve as they had reached maturation and viability.
Now, with five viable embryos stored in liquid nitrogen and ready to be used for in vitro (outside the body) fertilization, the next step – preparations to transfer the embryos into female southern white rhinos – is already taking place.
A southern white rhino bull named Ouwan was moved from Lewa Wildlife Conservancy in northern Kenya to Ol Pejeta Conservancy in November 2020. Ouwan, a proven champion breeder, is expected to be a reliable indicator through his behavior of where Ol Pejeta's female southern white rhinos are in their reproductive cycles. He has been sterilized though, to ensure the park doesn't end up with a herd of southern white rhinos carrying little Ouwans. Once the sterilization has been confirmed in March this year, Ouwan will be monitored to see if any potential female surrogates are ready to be artificially inseminated. If so, the next step of the plan will be implemented, and the world will wait with bated breath to follow the continuing saga of whether it's possible to pull these animals back from the brink of extinction.
“This is a big win for Kenya and its partners, as the northern white rhinos are faced with the threat of imminent extinction,” Kenya’s Tourism and Wildlife Minister Hon. Najib Balala said in a statement. "I am delighted that the world has a chance through use of cutting edge and innovative technologies to save this threatened wildlife species for posterity and that Kenya is playing its part in this critical conservation effort," he said in another.
"Remember, extinction is forever," Balala added. "Once we lose this species we will have lost an iconic animal which will not be seen again by future generations.”