Scientific breakthrough: White rhino rescue seems possible

Worldwide, many of the surviving rhinoceros species are considered “threatened with extinction”. Things are especially bad for the northern white rhinoceros in Central Africa – there are only two of this species left, and they are both females.

Despite these circumstances, researchers are trying to ensure the species’ survival. A team from the BioRescue consortium has achieved a milestone in this regard: the researchers have succeeded in growing primordial germ cells – the precursors of egg cells and sperm – from both embryonic stem cells and induced pluripotent stem cells (iPS cells).

The researchers report on their success in the journal Sciences Advances. Their mission: generate sperm and egg cells from rhino skin cells, among other things. Female specimens, belonging to the closely related species of the southern white rhinoceros, are said to carry the resulting embryos.

Masafumi Hayashi, lead author of the study from Osaka University, says: “It is the first time that primordial germ cells of a large and endangered mammalian species can be generated from stem cells.” So far, this has only been achieved with rodents and primates.

Using the newly developed stem cell techniques, other endangered rhino species should also be saved in the future, Hayashi explains: “There are five rhino species and almost all of them are classified as endangered species on the IUCN Red List.”

However, the researchers are already facing the next challenge. Because the primordial germ cells have to grow into functional egg cells and sperm cells in the laboratory. The progenitor cells are relatively small compared to egg cells and mainly have a double set of chromosomes, one of the scientists explains. Therefore, suitable conditions must now be found under which the cells can grow and halve their chromosome set.

Horses may play a role in this. Since horses are among the closest relatives of rhinoceroses from an evolutionary point of view, their ovarian tissue could potentially be useful for the challenges ahead.