Hybrid embryos of the northern white rhinoceros, doomed to extinction after the recent death of the last male, and a related subspecies have been created by assisted reproduction technologies within a laboratory, according to a study published in Nature Communications.
“This is the first time in the world rhinoceros embryos have been obtained in vitro,” said project director Thomas Hildebrandt of the Leibniz Institute for Zoological Research and Wildlife in Berlin (IZW).
The working group led by the German scientist cultivated the embryos after removing ova from southern white rhinoceroses and fertilizing them with sperm from previously stored northern white rhinoceroses.
Once confirmed that the assisted reproduction method works, researchers are now planning to create pure northern white rhinoceros embryos. To do this, they will fertilize in August or September the last two northern white rhinoceros eggs that exist in the world, said a spokesman for the IZW.
The advance constitutes the first hybrid embryo created through “in vitro” fertilization that reaches the blastocyst stage -with 5 or 6 days of development- with a complex cellular structure.
The two females, the only ones of northern white rhinoceros that remain alive in the world, are now sterile and live in a natural reserve in Kenya. Given their inability to gestate the embryos, two females of the southern subspecies will become the surrogate mothers.
The 2012 Nobel Prize in Physiology or Medicine, won by Shinya Yamanaka, who discovered that mature cells can be reprogrammed to become pluripotent, allowed a new approach by combining “assisted reproduction technologies with oocyte collection”, Hildebrandt said at a press conference.
The northern white rhinoceros comes from central Africa and eastern Africa. In 2008 the last specimens of this subspecies that lived in freedom died.