'Immortal cell' will save millions of lab animals

MILLIONS of laboratory animals that die each year in scientific research could be saved by a new approach to growing animal cells in the test-tube.

Scientists believe they may be able to replace many of the animals that they have to use to test new products with 'immortal' cells that can live for months or even years in a test-tube.

In the pharmaceutical industry, for example, experts estimate that the new approach could cut by 99 per cent the number of animals killed during testing of drugs. A typical drug would need about 1,000 mice for testing, according to one expert. The new approach could reduce this to 10.

In Britain, more than three million animals - mostly mice and rats - are used in scientific research each year. The majority are used by companies and research institutes to test the safety of industrial or medical products.

The 'immortal' cells have been created using genetically engineered mice. Each cell in these mice is theoretically capable of growing in a laboratory Petri dish to test, for instance, the toxic side- effects of drugs.

Scientists at the Ludwig Institute for Cancer Research in London and the Medical Research Council's National Institute for Medical Research, Mill Hill, created the genetically engineered mouse using a gene from a monkey virus that causes cells to divide continuously.

However, by attaching the gene to a genetic 'switch' that turns on when the temperature falls by a few degrees, the scientists have been able to ensure that the mouse cells only become 'immortalised' when grown in a test-tube at 33C, about five degrees below body temperature.

After scientists dissect the cells of interest from the mouse, they put them into a dish of nutrients. When the temperature is lowered, the immortalising gene is switched on and the cells begin to divide, making perfect copies of the original. Scientists from the drug industry said they can test a thousand new drugs using the cells from a single animal.

The power of the technique is the ability to grow cells from almost any organ or tissue in the body. Researchers have already been able, for the first time, to grow continuously certain types of cells from the brain, muscles, bone marrow and bowel.

Professor Mark Noble, head of the cellular neurobiology laboratory at the Ludwig Institute and one of the members of the original reseach team, said that, in addition to using fewer animals, the development will allow scientists to 'do things they have never done before' by allowing better access to continuously dividing, healthy cells of different tissues. Prof Noble said that many scientists and drug companies throughout the world had expressed an interest in the research.

There are two reasons why fewer animals will be needed. First, test-tube cells can be used to screen out drugs that prove ineffective. Second, when promising drugs are tested for side- effects on animals - which will still be necessary - fewer animals will be needed because the test- tube cells are identical to those growing in the living animal.

Gilly Griffin, managing editor of the journal Alternatives to Laboratory Animals, said the new developments were a promising way of reducing the total number of animals in research.

Tomorrow on the Science page of the Independent: Why our body's cells must die, so that we can live.