Saving from the brink
Andrea Barthelemy –
An international team of scientists aims to use advanced stem-cell technology to save the northern white rhinoceros from extinction.
They plan to reproduce the critically endangered rhinos —only three individuals remain alive — using induced pluripotent stem (iPS)cells, reported the Berlin-based Leibniz Institute for Zoo and Wildlife Research (IZW), one of the organisations taking part in the rescue project.
So-called iPS cells are mature cells taken from any tissue — usually skin or blood — that have been genetically modified to behave like embryonic stem cells. This means they have the ability to form any adult cell type and could be induced to become sperm and egg cells. The three surviving individuals — a male and two females — are still able to provide natural sperm and egg cells as well.
If all goes according to plan, in-vitro fertilised eggs could be introduced into surrogate mothers — for example southern white rhinos, whose number in the wild is estimated at 20,000 — that then bear fertile northern white rhinos.
“A success offers new possibilities in the fight against species extinction caused by humans,” the IZW said in a press release.
The procedure was discussed in Vienna in December at a conference of international cell experts. Among the participants was Katsuhiko Hayashi, a stem-cell scientist at Japan’s Kyushu University, who has succeeded in breeding mice from simple skin cells.
Two northern white rhinos died in captivity last year: a 41-year-old female at San Diego Zoo Safari Park in the United States, and a 32-year-old female at Zoo Dvur Kralove in the Czech Republic. The remaining three individuals of the rare subspecies live at Ol Pejeta Conservancy in Kenya.
The animals’ age and reproductive challenges make the possibility of natural reproduction unlikely, the IZW said. This past summer, a South African veterinarian unsuccessfully attempted in-vitro fertilisation with the male’s sperm and eggs extracted from the females.
DNA from a dozen northern white rhinos is being preserved in gene banks in Berlin and San Diego. Scientists will report on the progress of their rescue plan in the coming year. — dpa