Iron lung gives lab mice a new lease of life - but not for long

Roger Dobson on how experiments on mice can now be extended

GOOD, or perhaps bad, news for laboratory mice ... a miniature iron lung has been invented to bring them back from the dead - so that researchers can carry on with experiments.

Until now mice damaged as a consequence of experimental work were simply written off. But the demands of modern science mean that there is often a considerable amount of time and money invested in each mouse, particularly if they have been genetically altered.

According to Dr Chi-Sang Poon, senior research scientist at Harvard and the Massachusetts Institute of Technology, a mutated mouse is now worth around pounds 120. But that investment can be lost if the mice die, and one of the problems with genetically modified mice is that they are prone to respiratory failure.

Dr Poon and colleagues have designed a miniature iron lung based on the principle of the machines developed for treating polio patients.

As with the iron lung, the mouse is put into a cylindrical chamber, its head sticking out of one end. A rubber cuff around the animal's neck seals the chamber and the pressure in the chamber is oscillated up and down, causing the lungs to inflate and deflate.

The past decade has seen huge advances in transgenic technology where mutant mice are bred with genetic modifications in order to mimic various diseases in humans. In that way the mice can be used as substitutes for humans for the testing of various therapies.

Transgenic mice have been used for a wide range of research, from studies of the central nervous system, to the treatment of human lung diseases like emphysema and fibrosis. But scientists have found that there can be side effects.

"Unfortunately, in some instances, genetic manipulation may provide unanticipated or undesired side effects that may render the mutants non viable," reports Dr Poon.

The tiny machine that he and his team have developed means that the mice can now be resuscitated and as a result observations to assess the effects of the experimental treatments can continue. Tests on the machine, which is likely to be marketed around the world, including the UK, show it extends the life expectancy by 50 per cent.