A bold effort to save the northern rhino

There are only two northern rhinos in the world. Both are females. To maintain their subspecies, a group of scientists turned to advanced reproductive technologies.
Introductory photo of female Fatu after surgery
Photo by Ami Vitale

On a freezing day in December 2009, four northern rhinos were picked up from Dvur Kralove and transported to Prague Airport. Accompanied by a veterinarian and placed in special wooden boxes, they flew to Kenya. There they were loaded into DHL trucks and taken to Ol Pejeta's wild nature.
Four individuals - two males named Suni and Sudan and two females named Najin and Fatu - represented half the surviving population of white rhinos, a subspecies of white rhinos distinguished by hairy ears and shorter front horns. According to Save the Rhino, around 1960 around Chad, the Central African Republic, Sudan, the Democratic Republic of the Congo and Uganda, around 2 360 were northern white rhinos. But in 1984, violent poaching and civil violence reduced their population to roughly 15.



Twenty-five years later, in the year 2009, only eight northern rhinos remained - all of whom were accommodated either in the Court of Justice in the Czech Republic or in the San Diego Zoo. Only four of them were potentially fertile. Conservationists hoped that transporting these four rhinos to Ol Pejet, their native Africa, with warmer climates and extensive grassland, would inspire them to reproduce and allow the subspecies to recover.

Wildlife Ranger Zacharia Mutai comforts Sudan, the last male northern white rhino, shortly before 19 died. March 2018 at Ol Pejeta Wildlife Conservancy in Northern Kenya.
Photo Ami Vitale, Nat Geo Image Collection

Although rhinoceros breeders have witnessed several attempts at mating, Fatu and Najin remained infertile and eventually were considered unable to give birth to a chick. Meanwhile, a few of their relatives began to die. In year 2011 died in Dvur Kralove older female Nesari. She was followed by Suni, one of the males in Ol Pejeta, Angalif, Nabire, Nola, and in the spring of 2018, Sudan, the last male of the northern white rhino on Earth. Since then, Fatu and Najin have been the only representatives of their kind.
While death was devastating, scientists were ready. For years, Thomas Hildebrandt, head of reproduction management at the Leibniz Institute for Zoo and Wildlife Research, and his team collected and frozen semen from several male white rhinos - including Sudan. In 2014, after learning that Fatu and Najin were probably infertile, he organized an international team that included the Dvur Kralove Zoo, the Kenya Wilderness, Ol Pejeta Conservancy and Avantea, the Italian Animal Reproduction Laboratory. The group devised a scheme of regeneration of the Northern White Rhinoceros population by in vitro fertilization, a process whereby egg and sperm are fertilized outside the body.



The team announced significant progress towards this goal: 22. On August 30th, the team successfully obtained the eggs of Fatu and Najin females - an act no one had previously attempted on northern white rhinos. After years of research, preparation and practice, this is a critical first step towards breeding this critically endangered subspecies.

Egg retrieval

In preparation for an attempt to remove Fatu and Najin eggs, the team fine-tuned their extraction skills by practicing the extraction of eggs from Southern white rhinos. It is a delicate process due to the risk of anesthesia and the presence of nearby large blood vessels. In 2018, Avantea's Cesare Galli, an Italian veterinarian and embryologist famous for cloning the first horse, injected some of these eggs with the seeds of a northern white rhino to create hybrid blastocysts or early embryos. This showed that semen could produce transmissible embryos.

Eventually the team determined they were ready to really do it. They anesthetized Fatu and Najin in their confined spaces at Ol Pejeta and extracted their eggs - a complicated process that requires reaching the ovaries of animals a few centimeters inside their bodies. Supervising veterinarians did not want to allow the rhino to sleep for more than two hours and often reminded scientists how much time was left, says Ol Pejet of Sampéré.

Fatu surrounds her breeders and veterinarian Stephen Ngulu. Partially anesthetized, it is gently guided to a soft sand bed before being fully anesthetized for surgery.
Photo by Ami Vitale

Upon completion of the procedure, the team rushed to put the collected eggs to a mobile lab created from a shipping container. While examining the cells with a microscope, Galli ordered everyone to remain silent so he could concentrate. Finally, he counted ten viable eggs - five from each female. The team was thrilled.

"I was here five years ago when we discovered that Fatu and Najin would not be able to reproduce naturally, and we realized that we had to look for artificial means," recalls Jan Stejskal, director of international projects at Dvur Kralove Zoo. "Now it's finally happening."
However, the team did not have enough time to revel in its success. The scientists carefully wrapped the eggs in square white coolers and quickly transferred them to a waiting helicopter that transported them to Nairobi airport. From there they embarked on a commercial flight to Frankfurt, where they switched to another plane to Italy.

Fatu undergoes a procedure to remove eggs from her ovaries. Robert Hermes, Thomas Hildebrandt, and Susanne Holtze of the Leibniz Institute for Zoo and Wildlife Research.
Photo by Ami Vitale

At Galli's laboratory in Cremona, the team will wait to find out which egg is maturing and fertilize it with the frozen semen of the northern rhino. If fertilized eggs develop into embryos, scientists cryopreserve them until they have refined their technique of transferring them to a southern white rhino.

New methods

Though an important step in the battle for the salvation of northern rhinos, it is certain that it is still soon to celebrate their salvation. Artificial insemination has successfully produced offspring of white rhinos, but fertilization of rhinos has never been completed in vitro. Now the scientists who have come are creating a viable embryo and trying to transfer it.
In addition, researchers reported that the quality of semen collected from northern white rhinos is poor and comes from only a few males - although Stejskal points to hybrid blastocysts as evidence of its viability.

Although a female southern rhino can carry the fetus of a northern white rhino by the term - which is uncertain - the northern rhino chicks may not be genetically diverse enough to sustain the population.

"The whole methodology is in its infancy," says Susie Ellis, executive director of the Rhino Foundation, a nonprofit nature conservation organization. "It's a long way from developing an embryonic cluster of cells to rhinoceros on the ground - and then a flock of rhinos on the ground."

The team of scientists is also working on an alternative - though equally demanding - approach. Using conserved skin samples, scientists hope to create gametes or ova and sperm from twelve northern white rhinos, which can then be added to the in vitro process to diversify the gene pool. Last year, the study indicated that tissue samples contain sufficient genetic diversity to eventually support a healthy northern rhino population.

Zachariah Mutai, chief caregiver of the Najin rhinos (left) and Fatu (right) at Kenya's Ol Oilse Conservatory, isolates the couple so veterinarians can begin the egg extraction process.
Photo by Ami Vitale

Jeanne Loring, a stem cell researcher at the Scripps Research Institute in La Jolla, California, working independently on a similar project, is optimistic that these techniques will eventually produce rhinos. “We make chicks in mice,” she explains, “And in our experience, anything that can be done in mice can be tailored to humans - and that also means white rhinos.

Fatu and Najin may die before such research takes place. But scientists hope that with the genetic material preserved, their death will only mean a break - not the end of their subspecies.

Source: National Geographic

Similar topics:

Outbreak of rhinoceros and juvenile A documentary film about tigers, rhinoceroses, and rhodes