Lab-made hybrid embryos could save the northern white rhino from extinction

The world mourned when Sudan, the last male northern white rhino, died this March at the Ol Pejeta Conservancy in Kenya.

He left behind two infertile females, Fatu, 18, and her mother Najin, 28, as the remaining members of the entire species.

Decades of widespread poaching and civil war devastated populations and conservationists are scrambling to prevent Earth's most endangered mammal from disappearing completely.

Now, scientists led by Thomas Hildebrandt, professor of wildlife reproduction medicine at the Freie University in Berlin, have created the first ever in vitro rhino embryos -- a major first step in a last-ditch effort to bring this subspecies back from the brink of extinction.

First test-tube hybrid rhino embryos

Hildebrandt and his team tested a newly patented procedure to harvest eggs from southern white rhino females, the most closely related subspecies to the northern white rhino.

The eggs were then matured and fertilized in the lab with cryopreserved (frozen) semen from two deceased northern white rhinos to create the first hybrid rhino embryos. The embryos will be implanted into southern white rhino surrogates, with a pregnancy expected later this year.

The next step is to travel to Kenya to perform a very delicate procedure: harvest eggs from Fatu and Najin to develop pure white rhino embryos, with both eggs and sperm coming from northern white rhinos.

A wider gene pool

The embryos developed using assisted reproduction techniques wouldn't contain the genetic diversity necessary to to create a self-sustaining population of northern-white rhinos, so scientists have simultaneously turned to stem cell technology to enlarge the genetic pool.

In 2011, induced pluripotents stem (iPS) cells were generated from Fatu's skin. Since then, four more stem cell lines were created from frozen northern white rhino tissue coming from several male and female rhinos.These are cells that have the capacity to develop into eggs and sperm.

Another tool

Hildebrandt emphasizes that applying these technologies to save highly endangered species is a last resort. The science involved is costly, poses risks to individual animals and can't replace traditional conservation methods.

Combined assisted reproduction techniques and stem cell technology can be part of a comprehensive, multi-faceted approach to species conservation that includes habitat preservation.