A frozen zoo is a storage facility in which genetic materials taken from animals (e.g. DNA, sperm, eggs, embryos and live tissue) are gathered and thereafter stored at very low temperatures in tanks of liquid nitrogen waiting to be reprogrammed into stem cells for optimal preservation over a long period (see cryopreservation). Some facilities also collect and cryopreserve plant material (usually seeds). The original idea comes from Gregory Benford's 1992 paper proposing a Library of Life.
Zoos such as the San Diego Zoo and research programs such as the Audubon Center for Research of Endangered Species cryopreserve genetic material in order to protect the diversity of the gene pool of endangered species, or to provide for a prospective reintroduction of such extinct species as the Tasmanian tiger and the mammoth.
Frozen Zoo at San Diego Zoo Conservation Research has been freezing biological materials from animals and plants in liquid nitrogen (−196 °C) since 1976. They currently store a collection of 8,400 samples from over 800 species and subspecies. Frozen Zoo at San Diego Zoo Conservation Research has acted as a forbearer to similar projects at other zoos in the United States and Europe including the Frozen Ark Project. However, there are still less than a dozen frozen zoos worldwide.
At the United Arab Emirates Breeding Centre for Endangered Arabian Wildlife (BCEAW), Sharjah, the embryos stored include the extremely endangered Gordon’s wildcat (Felis silvestris gordoni) and the Arabian leopard (Panthera pardus nimr) (of which there are only 50 in the wild).
The University of Georgia's Regenerative Bioscience Center is building the frozen zoo. Gathering material for a frozen zoo is rendered simple by the abundance of sperm in males. The scientists have already extracted cells from a Sumatran tiger named Jalal. Sperm can be taken from an animal following death. The production of eggs, which in females is usually low, can be increased through hormone treatment to obtain 10–20 oocytes, dependant on species. Some frozen zoos prefer to fertilize eggs and freeze the resulting embryo, as embryos are more resilient under the cryopreservation process. The zoo also collects skin cell samples of endangered animals or extinct species. Scripps Research Center has successfully made them in to a cultures of special cells,induced pluripotent stem (IPS) cells. Now, theoretically, they are able to make sperm and egg cells with old skin cells.
RBC Director Steven Stice and animal and dairy science assistant professor Franklin West thought of saving the endangered cat species that made it into a reality. Artificial insemination provides a remedy for animals who, due to anatomical or physiological reasons, are unable to reproduce in the natural way. Reproduction of stored genetic material also allows for the fostering of genetic improvements, and the prevention of inbreeding.
Modern technology allows for genetic manipulation in animals without keeping them in captivity. However, the success of their restoration into the wild would require the application of new science and a sufficient amount of previously collected material.