Scientists have created stem cells from two endangered species, which could help ensure their survival.

The northern white rhino is one of the most endangered animals on Earth, while the drill - a west African primate - is threatened by habitat loss and hunting. With countless endangered animals teetering on the brink of extinction throughout the world, the work of preservation has never been more important.

Scientists report in Nature Methods that the stem cells of these two species could be converted into different types of body cells.

Jeanne Loring and her colleagues at the Scripps Research Institute had been encouraged by the results on the rhino cells, which they had not really expected to be successful.

The best way to manage extinction is to preserve species and habitats but that is not always working, Oliver Ryder, director of genetics at the San Diego Zoo and co-leader of the study.

This kind of science entails a fair amount of trial and error, and the researchers expected it would work with the drill because there is lots of experience with primates. But the rhino was a different matter.

Studies using the stem cell approach are in progress to cure human diseases. However, scientists hope to be able to use stem cells to create eggs and sperm, which could be then used for breeding and boosting the genetic diversity of the endangered species.

Both animals, the researchers said, were chosen because they could benefit from stem cells now. For instance, the drill suffers from diabetes when in captivity, and stem cell-based treatments for diabetes being researched in humans suggest the same may work in these primates. The drill is closely related to the baboons and even more closely to the mandrill.

The northern white rhinoceros was chosen because it is one of the most highly endangered species on the planet, with only seven animals, all in captivity, in existence (two of which are in the San Diego Zoo Safari Park). They haven't reproduced in several years, and because the population is so small there is a lack of genetic diversity, which could affect their survival.

If the researchers can use the stem cells to make sperm and eggs from skin cells of deceased animals in the frozen zoo, they could reintroduce some genetic diversity into the population, while also increasing its size.

The stem cell research brings together conservation scientists with those involved in cutting-edge laboratory work.

However, it is not without a bit of sad irony that in a world where such advanced technologies exists to one day revive species from extinction, the often avoidable activities which threaten them have not yet been overcome.