The northern white rhino may be functionally extinct, its last male having died in March, but conservationists believe the subspecies could still be rescued from the brink — with a little help from science.
Researchers announced in a paper published Wednesday that they’d successfully created embryos in the lab using frozen sperm from long-dead northern white males.
The use of in vitro fertilization is a last-ditch effort to save the subspecies from total annihilation. IVF in rhinos, a controversial and extremely costly endeavor, has never before been successfully carried out.
In the new paper, published in Nature Communications, the scientists explained how they were able to fertilize eggs, or oocytes, taken from southern white rhinos with sperm from northern whites. The southern white rhino, which numbers about 17,000 in the wild, is a thriving sister subspecies of the northern white rhino.
Harvesting the oocytes from the southern white females was a challenging feat, the researchers said.
“You can’t reach the ovaries by hand, so we developed a special” 6.6-foot egg extraction device, Thomas Hildebrandt, a pioneer in reproductive science and the paper’s lead author, told BBC News. The team then used ultrasound to “very precisely inject a needle” into the area of the ovary that releases eggs.
Hildebrandt said the team needed to be very careful to not puncture a “huge artery” located near the ovaries which, if ruptured, could cause the rhino to bleed to death.
Later, to encourage fusion between sperm and eggs, the scientists said they zapped the frozen northern white rhino sperm, which had been somewhat languid at first, with electricity.
They were eventually able to produce several “high quality” early-stage embryos, Hildebrandt said. Two hybrid embryos, as well as one pure southern white rhino embryo, have since been cryogenically frozen.
These embryos “have a very high chance to establish a pregnancy once implanted into a surrogate mother,” Hildebrandt told Agence France-Presse. Scientists are still refining the technology to implant embryos into rhino surrogates.
Hildebrandt says he’s confident, however, that the process will soon be perfected. If all goes smoothly, the first pure northern white rhino calf could be born via IVF within 3 years, he said.
“Everyone believed there was no hope for this subspecies,” Hildebrandt told BBC of the northern white. “But with our knowledge now, we are very confident that this will work with northern white rhino eggs and that we will be able to produce a viable population.”
Poaching, fueled by demand for rhino horn, has driven the northern white rhino ― which had numbered over 2,000 as recently as 1960 ― to functional extinction. By the 1980s, just 15 animals remained on the planet.
In March, the last male of the subspecies, Sudan, died at the age 45. Today, just two females, Najin and Fatu, remain.
Hildebrandt said the goal is to collect eggs from Najin and Fatu, both of whom live on Kenya’s Ol Pejeta Conservancy, before the end of the year. But he warned the procedure could be risky.
“We are highly afraid something unexpected would happen, that would be a nightmare,” he told AFP.
It’s also unclear whether the two females will even have viable eggs to harvest. And even if the entire IVF procedure is successful, reservations have been voiced about the new population not being genetically diverse enough to thrive since the eggs of only two females and sperm from only a handful of northern white males would be used to create progeny.
But scientists involved in the rhino IVF project insist it’s still worth a shot.
“There have been many, many, many attempts to save rhinos by classical conservation methods and they’ve all failed,” researcher Marilyn Renfree told Australia’s ABC News. “This is the last possible step to save these guys.”
Other conservationists have said that even if the IVF effort doesn’t end up saving the northern white rhino, it will still represent a huge leap forward for animal reproductive science.
“They’ve made some big strides in advancing what has been known about artificial reproductive technologies and using IVF potentially to rescue genetic material for a species on the brink of extinction,” conservation biologist Guy Castley, who was not involved in the research, told ABC.
Experts have warned, however, of the dangers of relying too much on technology in the hopes of reversing the horrific things humans have done to the world’s species.
“It is important that we learn from the plight of the northern white rhino and we make sure what happened to it does not happen to other endangered species,” Terri Roth, vice president for animal sciences at the Cincinnati Zoo, who was also not involved in the research, told the BBC.
“As impressive as science can be, we should not reach a point where these hi-tech approaches are the only source of hope for rescuing genes of valuable individuals, subspecies or entire species,” she continued.
Poaching, Roth added, remains the primary threat facing the world’s five living rhino species, four of which are considered vulnerable or critically endangered. The government of South Africa, home to 80 percent of the world’s rhinos, warned earlier this year that rhino poaching remains at “crisis levels.”
“Rhino populations are still in critical danger,” Jimmiel Mandima of the African Wildlife Foundation told National Geographic in January.