Sudan's death: a legacy of greed

👉How science is stepping in to save the northern white rhino from extinction

The last male northern white rhinoceros, Sudan, died on March 19 at the age of 45, at Ol Pejeta Conservancy in Kenya, where he spent the last nine years under the watch of a 24-hour armed guard.

There was a time when northern white rhinos could be found in southern Chad, the Central African Republic, southwestern Sudan, northwestern Uganda, and the Democratic Republic of the Congo. In 1960, more than 2,000 were remaining, according to a World Wildlife Fund report. The number shrank to 15 in 1984 as they were hunted for their horns, an important ingredient in traditional Vietnamese medicine. Only two northern white rhinos remain now: Sudan’s daughter Najin and granddaughter Fatu, neither of whom will be able to carry a pregnancy to term.

Where traditional conservation methods failed to save this subspecies, science is stepping in. From the sperm of four northern white rhino bulls and living cells collected from 13 northern white rhinos before they died, researchers from Germany, the U.S., Kenya, Japan, Australia, Austria and the Czech Republic are planning a two-pronged approach – in vitro fertilisation and stem cell technology to resurrect the subspecies. From Berlin, a team of scientists being led by Professor Thomas Hildebrandt, Department Head, Reproduction Management, of the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW), will go to Kenya in May to extract eggs from Najin and Fatu. In Cremona, Italy, the eggs will be fertilised with the sperm of northern white rhino bulls. Sudan’s sperm is not viable due to lack of genetic distance. Once the eggs are fertilised, they will need surrogate mothers and the closest living relatives are the southern white rhinos. IVF has been performed successfully on the Asian lion and the team at Leibniz-IZW is developing the procedure for rhinos. Steven Seet from Leibniz-IZW is optimistic about IVF. In the next two to three years, it is probable that the world will welcome the first living IVF northern white rhino, he said in an email interview.

However, one rhino will not resurrect a species or subspecies. Genetic diversity is the key, and this is where the expertise of Katsuhiko Hayashi, a reproductive biologist at Kyushu University in Fukuoka, who produced baby mice from mouse skin cells, comes in. He reprogrammed cells to behave like human embryonic stem cells, which were used to grow fertile mouse egg cells in a dish. Mr. Hayashi’s team will attempt to replicate this with northern white rhino cells. The living cell material of 13 northern white rhinos are stored in laboratories in Germany, the U.S. and Kenya. The aim is to take the cells from existing samples and develop them back into embryo stem cells. After reprogramming, the stem cells can form one cell which can grow into a sperm, and another into an egg. The fertilised egg will be transferred to the surrogate mother. Mr. Seet estimates that over the next four years alone, researchers will need at least €5 million to keep the project going. It is a hefty price to pay for our greed.

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