Can the world’s most endangered animal be saved by a test tube?
THEY are the world’s most endangered animals, with just two females left.
But a world-first breakthrough in IVF could bring the northern white rhino back from the brink of extinction.
The last male, Sudan, died of old age in March, meaning scientists couldn’t save the species by getting animals to breed naturally. But now they have used frozen northern white rhino sperm to create embryos to implant into a female rhinoceros. If successful, this could see a calf born within three years in Kenya – and even more at Longleat Safari Park in Wiltshire, southwest England.
The embryos are not pure northern white rhinos, as they were created using the eggs of the closely related southern white rhino. But the same method could soon be used with eggs taken from the surviving northern rhinos in captivity in Africa.
‘Our results are very promising’
Better still, the embryos give researchers a source of stem cells, which could be turned into better quality sperm and eggs in the lab. While IVF has been achieved in horses, it is the first time embryos have been created which have a chance of becoming rhino calves, by reaching the ‘blastocyst’ stage at which they are ready to be implanted.
Professor Thomas Hildebrandt, who led the experiment from the Leibniz Institute for Zoo and Wildlife Research in Germany, said: ‘These are the first in vitro-produced rhinoceros embryos ever. They have a very high chance to establish a pregnancy once implanted into a surrogate mother.’
‘Our results are solid, reproducible and very promising. Now we are well prepared to go to Kenya and collect oocytes [a cell produced in the ovary] from the last two northern white rhino females in order to produce pure blastocysts where both eggs and sperm are from northern white rhinos.’
The fertility treatment used frozen sperm from three dead northern white bulls.
However, this was found to be poor quality, so researchers used a technique more often used in infertile human couples to inject the sperm directly into the eggs.
The international team, whose results are published in the journal Nature Communications, say they could put hybrid embryos into female rhinos in just over a year.
A pregnancy lasts 16 months, so calves could be born by late 2020 or early 2021.