Wednesday, June 2, 1999 Published at 18:05 GMT 19:05 UK
Cells used to test drugs
Scientists have tested mice cells for their reaction to toxins
Scientists are perfecting a way to use cells to test for poisons in experimental drugs before they are tried out on animals or humans.
Biotechnology company VistaGen, based in California, believes human embryonic stem (ES) cells can be used to develop a quick, accurate way to identify drugs that might damage the liver.
The liver is the organ that breaks down most drugs, and it is the most likely part of the body to be damaged if toxins are released at this stage.
In an attempt to screen out dangerous compounds early on, pharmaceuticals companies often test the effects of potential drugs on liver cells taken from cadavers.
But once outside the body, human liver cells often stop producing the enzymes that break down drugs into toxic by-products.
This means the side effects of some drugs are not spotted until they show up in animal tests or even in clinical trials.
ES cells - which have the potential to develop into any of the body's tissues - produce high levels of enzymes that are normally found in the liver.
Therefore they offer a potential solution to the problem of how to test drugs outside the body.
VistaGen's scientists have treated mouse ES cells with two drugs known to damage the liver, and several others with no known toxicity.
The cells produced a distinctive spectrum of proteins in response to the toxic drugs. The company plans to repeat the experiment with human ES cells.
Frank Sistare, a pharmacologist with the Food and Drug Administration in Washington DC, says that the VistaGen team must now prove that ES cells predict drug toxicity better than current cell-culture systems.