Scientists have successfully created two embryos of the near-extinct northern white rhino in a landmark effort to save the species.
The international team of researchers and conservationists drew on IVF procedures to create the embryos from fresh eggs collected from the two remaining female rhinos and frozen sperm from dead males.
The achievement, announced at a press conference in Italy on Wednesday, paves the way for specialists to transfer the embryos into a surrogate mother – a southern white rhino – in the near future.
“Today we achieved an important milestone on a rocky road which allows us to plan the future steps in the rescue programme of the northern white rhino,” said Thomas Hildebrandt, head of the BioRescue project at Leibniz Institute for Zoo and Wildlife Research.
The embryos were created at Avantea Laboratories in Cremona, Italy, and will be stored in liquid nitrogen until the team is ready to transfer them to the surrogate mother.
Northern white rhinos have been in decline for decades. By 2018 the population had dwindled to two remaining females, Najin and Fatu at Ol Pejeta Conservancy in Kenya, who are the last of their kind in the world.
Cesare Galli said his team collected five immature eggs from each female which were airlifted to the Italian laboratory. There, the eggs were incubated to provide three mature eggs for Najin and four for Fatu.
The scientists then used a common IVF procedure called intracytoplasmic sperm injection, or ICSI, to fertilise the eggs. Fatu’s were injected with thawed out sperm taken from a dead male called Suni, while Najin’s eggs were fertilised with poorer quality sperm collected from a male called Saut. After 10 days of incubation, two of Fatu’s eggs developed into viable embryos, but none of Najin’s made it.
“Five years ago, it seemed like the production of a northern white rhino embryo was an almost unachievable goal, and today we have them,” said Jan Stejskal at Dvůr Králové Zoo in the Czech Republic, where Najin and Fatu were born.
The last of the male northern white rhinos was 45-year-old named Sudan who rose to fame in 2017 when a fundraising effort listed him on the Tinder dating app as “The Most Eligible Bachelor in the World”. He was put down in March last year for health reasons brought on by old age.
The dramatic decline of the northern white rhinos was driven by poaching. Sudan was the last known male to be born in the wild, in the country from which he got his name. The southern white rhino and the black rhino are also targeted by poachers, who kill them for their horns to supply illegal markets in parts of Asia.
About 21,000 southern white rhinos still exist and females will be used as surrogate mothers in the effort to save the northern species. Scientists hope that the first northern white rhino will be born from an IVF embryo in the next two years.
Even if healthy northern white rhino calfs are born from the IVF embryos, conservationists will still face an enormous challenge in the lack of genetic diversity in the population. One way to broaden the animals’ gene pool is to create eggs from rhino skin cells stored around the world, but the technology may not be available for another decade.
“This is a major step forward in our efforts to recover the northern white rhinos,” said Richard Vigne, managing director of Ol Pejeta Conservancy. “We have a very long way to go and we must remember that, for most species facing extinction, the resources that are being dedicated to saving the northern whites simply don’t exist. Global human behaviour still needs to radically change if the lessons of the northern white rhinos are to be learned.”