Northern white rhino - Escolpio
A northern white rhino. Only seven specimens remain in existence, all in captivity. Photo by Escolpio
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An Israeli scientist has led the ground-breaking research team that has produced the first stem cells from endangered species, a breakthrough that could potentially save animals in danger of extinction and bolster endangered species' health in captivity.

The research was led by Israeli scientist Dr. Inbar Friedrich Ben-Nun at the Scripps Research Institute in California.

The stem cells were produced from normal skin cells and the research was conducted by both San Diego Zoo and Scripps Institute scientists. Zoo workers have been preserving skin cells and other tissue samples of some 800 species since the 1970s.

About five years ago, Oliver Ryder, director of genetics at the San Diego Zoo and co-leader of the study, contacted Jeanne Loring, professor of Developmental Neurobiology Jeanne Loring at the Scripps Institute, about the possibility of using the tissue-sample bank to generate and store stem cells.

Stem cells are biological cells found in all multicellular organisms, that can be turned into any type of cell in the body - a characteristic called pluripotency. The cells can even be turned into sperm or egg cells, and used in assisted reproduction to make more individuals of the species.

In adult organisms, stem cells and progenitor cells act as a repair system for the body. The research's long-term objective is to turn the stem cells into egg and sperm cells and fertilize them in a surrogate animal.

Until this is possible, scientists will try to produce a bank of stem cells from various species in danger of extinction.

Researchers from the Scripps Institute detail their work in the online September 4 edition of the journal Nature Methods. They started with normal skin cells from the west African monkey called the drill - genetically a close relation to humans - and the northern white rhino.

"Stem cell technology provides some level of hope that they won't have to become extinct even though they have been completely eliminated from their habitat," Ryder said.

That is also the hope for the northern white rhinoceros, one of the first two animals included in Ryder's new "stem cell zoo." Only seven specimens remain in existence, all in captivity with two of them housed in San Diego.

At the time, scientists seeking to use stem cells to cure human disease had not yet found a reliable technique for turning normal adult cells into stem cells that can give rise to nearly any type of tissue or cell in the body. "We are the first to take this method forward to extinct species," says Dr. Ben-Nun. "We hope that in the not-so-distant future, it will be able to create new individuals of the same species."

"The idea itself is interesting, but many years may pass until it can be implemented," says Prof. Joseph Itskovitz-Eldor of the Technion's medicine faculty, who took part in the first experiment to produce human stem cells.

"Even if an egg and sperm cell can be produced from stem cells," he added, "it is not easy to fertilize them. It's like in vitro fertilization and each animal needs specific conditions for that. However, the biotechnological development is so rapid that what seemed imaginary a decade ago is already happening. There are always surprises."

Ben-Nun agrees. "It won't happen tomorrow, but it could happen sooner than we think. Our research's goal is to show that it can work and we want to bring that to the attention of the people dealing with preserving species and stem cells," she said.