Defenseless Rat Proves Knockout in Lab
An Animal Rights Article from All-Creatures.org

FROM

Andy Coghlan on NewScientist.com
August 2009

The creation of a lab rat with no functioning immune system...It also heralds the arrival of many other types of knockout rats vital for research.

ar-defenseless

The creation of a lab rat with no functioning immune system is opening up the possibility of more realistic testing of cancer treatments, transplantation techniques and other therapies. Such animals are useful to researchers because the immune response in a normal animal can complicate test results.

Until now, mice have been the only lab animals readily available with no immune system. They are produced by knocking out key genes in mouse embryonic stem cells required for the immune system to function. Development of a rat equivalent has lagged behind, as the first "knockout rats" were not engineered until late last year.

Now researchers at Transposagen Biopharmaceuticals of Lexington, Kentucky, have announced that they have made what they call a "SCID rat" - so called because the animal's lack of an immune system leaves it with a condition resembling a human syndrome called severe combined immune deficiency. The SCID rats were made by mutating embryonic DNA in a way that "switched off" the immune system.

The SCID rats will aid research into human illnesses because rats are more closely related to humans than mice, so experiments on them give a better idea of what may happen in people. A mouse's heart beats 5 to 10 times as fast as a human's, whereas a rat's heart rate is closer to ours. Because rats have similar liver enzymes to humans, they clear poisons in the same way. And because rats are intelligent, future knockout rats could be used for research on memory, learning and neurological disease.

Rats are also "small enough to be cost-effective and easy to breed", says Eric Ostertag, Transposagen's founder and CEO.

Ostertag predicts that as well as having practical potential in immunology, cancer research and transplant research, the SCID rat's significance stretches even further. It also heralds the arrival of many other types of knockout rats vital for research, he says.

Please visit our image gallery to see how rats and mice are brutalized in laboratories.

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