BioRescue creates four new embryos and braces itself for next steps of the northern white rhino rescue mission
The international consortium of scientists and conservationists working towards preventing the extinction of the northern white rhino through advanced assisted reproduction technologies is happy to announce that in March and April 2021, four additional northern white rhino embryos were produced.
This is the most successful series of procedures – from oocyte collection in Kenya to in vitro fertilisation and cryopreservation in Italy – the team of Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW), Safari Park Dvur Králové, Kenya Wildlife Service, Ol Pejeta Conservancy and Avantea has ever conducted. Additionally, the team confirmed the successful sterilisation of the southern white rhino bull Owuan, which was conducted in December 2020.
The bull will be introduced to the Ol Pejeta southern white rhino females that have been identified as potential surrogate mothers for future northern white rhino offspring.
Females Najin and Fatu at Ol Pejeta Conservancy, Kenya, are the only remaining northern white rhinos in the world. To prevent the extinction of the northern white rhino, and since 2019, an international consortium of scientists and conservationists called BioRescue and lead by Leibniz-IZW has been harvesting immature egg cells (oocytes) from the two females and artificially inseminating these using frozen sperm from deceased males in order to create viable northern white rhino embryos. In the near future, the embryos will be transferred into southern white rhino surrogate mothers to create northern white rhino offspring.
On March 28th, 2021, 19 oocytes were retrieved from Fatu’s ovaries using a probe guided by ultrasound, after the animal was placed under general anaesthesia. Fatu is the youngest of the two northern white rhinos, Najin’s daughter and Sudan’s granddaughter. Both the anaesthesia and the ovum pickup procedure went smoothly and without complications. After incubating and maturing the egg cells in the Avantea laboratory in Italy, 14 of them were fertilised with thawed sperm from deceased northern white rhino bull Suni using a procedure called intra-cytoplasmic sperm injection (ICSI). Four fertilised oocytes developed into a viable embryo with the help of Geri®, an innovative benchtop incubator with integrated continuous embryo monitoring capabilities designed to provide an individualised and undisturbed incubation environment donated by Merck. The embryos are now stored in liquid nitrogen along with the five embryos from previous procedure – for a total of nine embryos, all derived from oocytes collected from Fatu.
During the most recent procedure, Najin, who is now 31, was put only in a light standing sedation and was examined via ultrasound. After the results of the ultrasound, the team decided not to attempt the procedure as she apparently had not developed enough promising oocytes. The consortium will soon discuss thoroughly if and how to continue the oocyte collections with Najin, as ethical risk assessments are a pivotal part of the programme.
THE NEXT PHASE
Another very important step in the success of the BioRescue programme was the selection and sterilisation of the southern white rhino bull Owuan in December 2020. The animal was sterilised by the BioRescue team with a minimally invasive non-surgical procedure using state-of-the-art equipment. The sterilisation went smoothly and without any complications. In March 2021, the BioRescue team confirmed via electroejaculation that the sterilisation was indeed successful. Owuan has recovered well from the examinations and is up to his future role: as a sterilised bull, he will reliably indicate through his behaviour the reproductive cycle of potential surrogate mothers without any risk of impregnating them. This indication is a crucial prerequisite for transferring the embryos into surrogate mothers at the correct timing of their reproductive cycle. Under the guidance of Kenya Wildlife Service, the team carefully planned the location of selected southern white rhino females in Owuan’s company and this introduction will take place in the coming weeks.
BioRescue research programme, that is significantly funded by the German Federal Ministry of Education and Research (BMBF) and additional donors such as foundation Nadace CEZ, the philanthropist Dr Richard Mc Lellan and Merck EMD foundation, will continue with its ambitious plan to create more embryos from oocytes collected from the northern white rhino females in a three- to four-month cycle as long as the COVID-19 pandemic allows for the team to travel to Kenya. With the sterilisation confirmed and relocation of surrogates planned, the next milestone of the programme is getting within reach.
“We are excited with the laboratory outcome of the last ovum pick up in March. With nine pure northern white rhino embryos now developed, the partners in the project should embark on the next phase of the project-embryo transfer into the surrogate southern white females at Ol Pejeta Conservancy. We are eager to get the progeny from the project that will guarantee survival of the species”,
Hon Najib Balala
Kenya’s Cabinet Secretary
Ministry of Tourism and Wildlife