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The Northern White Rhinoceros (NWR) are functionally extinct, with only two females of this species on the planet. But now, an international team of scientists has now successfully created hybrid embryos from white rhinoceros eggs (SWR) and NWR sperm using badisted reproductive technologies (ART).
This is the first generation of blastocysts (pre-implantation). embryos) rhinoceros in a test tube
The international team also established stem cell lines from ROS blastocysts with typical characteristics of embryonic stem cells.
The breakthrough is published in Nature Communications. are the first rhinoceros embryos produced in vitro, "explains Professor Thomas Hildebrandt, head of the Department of Reproductive Management at the German Leibniz Institute for Zoological and Wildlife Research (Leibniz-IZW) in Berlin. "They have a very good chance of establishing a pregnancy once implanted in a surrogate mother."
An international team of researchers has succeeded in adapting the reproductive techniques used in horses to the particular circumstances of rhinoceros species, opening the possibility of bringing this could be achieved by adopting the procedure for the oocytes to be taken on the last two living females of the Northwest. Female SWRs could serve as surrogate mothers to an emerging NWR population.
Unlike NWR, there are about 21,000 SWRs in southern Africa today.
Using a patented technical device nearly two meters long, scientists have been able to repeatedly and safely collect rhinoceros oocytes. The ultrasound device is placed trans-rectally. Once a follicle appears on the screen of the ultrasound laptop, a special needle can be activated to pierce the intestinal wall in the ovary and harvest the oocyte at from the follicles.
Oocytes were collected from SWR females in European zoos and then shipped to AVANTEA, an badisted reproductive technology (ART) center for large animals in Italy.
"In our laboratory we were able to develop procedures to mature oocytes, fertilize them by intracytoplasmic sperm injection (ICSI)," explains Professor Cesare Galli, from AVANTEA. "For the first time, we have developed rhinoceros blastocysts – an early stage of embryo – in vitro, as we usually do for cattle and horses. "
Several embryos are now cryopreserved to be transferred to surrogate mothers Pregnancy to term
"For fertilization, cryopreserved sperm from deceased NWR males was used," comments Jan Stejskal, director of international projects at Safari Park Dvůr Králové in the Czech Republic. "Successful development of a hybrid embryo is an important step towards the first birth of a northern white rhinoceros through artificial breeding techniques. Already, half of the genetic information on the hybrid embryo comes from the NWR.
The two women of the NWR were born in Dvůr Králové and currently reside at the Ol Pejeta Conservancy near Mount Kenya
solid, reproducible and very promising, "says Hildebrandt. "We are now well prepared to go to Kenya and collect oocytes from the last two NWR females to produce pure NWR blastocysts where the eggs and spermatozoa come from NWR."
Scientists performed more than 20 European oocyte collections, generating more embryos than those reported in the publication. They are currently working on the procedure for transferring embryos.
However, since there are only two females left and only four males of semen are available, badisted reproduction and in vitro fertilization techniques would probably not be enough to create self-sufficiency.
That is why scientists are working on an additional approach and plan to generate gametes through stem cell technology
"In the future, our goal is to produce primordial germs in vitro iPS cells (induced pluripotent stem cells) obtained from somatic cells, cryopreserved in the past, from multiple NWR individuals, "says Dr. Sebastian Diecke, stem cell expert at the Max Delbrück Center for Molecular Medicine of the United States. Helmholtz Association (MDC) in Berlin, Germany, and Professor Katsuhiko Hayashi, Stem Cell Expert in the Department of Biology and Stem Cell Medicine, Kyushu University, Japan. "In a second step, these germ cells will then be transformed in ovules and spermatozoa. "
This would significantly expand the founding genetic diversity of the future NWT population
The combination of stem cell research is a plan for how to save highly endangered species that have already declined to numbers that make conventional conservation efforts impossible.
"Pluripotent stem cells have the ability to renew themselves indefinitely and to grow in any cell of a living organism. At Avantea, we have succeeded in generating SWR embryonic stem cells with all the characteristics of undifferentiated cells and a great capacity for differentiation in different cell lines, "reports Prof. Cesare Galli.
The embryonic stem cell lines obtained in this study was transferred to Dr. Diecke's laboratory, as they will serve as a model to differentiate iPS cells into germ cells and possibly into gametes.
Northern white rhinos are the most endangered mammals on the planet. conservation to save this species were thwarted by human activities such as poaching, civil war and loss of habitat.This resulted in a reduction of the population from 2,000 individuals in the 1960s to only two women In March 2018, the last man from the NWR – Sudan – is death of old age
