PARIS - Researchers at France's National Institute for Health and Medical Research (Institut National de la Santé et de la Recherche Médicale - INSERM) have developed a technique for viewing gene therapy at work in the body.

It enables the passage of DNA or RNA strands through an organism to be visualized in vivo, utilizing positron-emitting tomography. This technique, which is already used in fundamental research and pharmacology, enables a molecule marked by a radioisotope to be localized within the body, and hence its passage through the organism to be tracked.

In its study, the research team led by Luigi Di Giamberardino, who heads an INSERM laboratory attached to the Life Sciences Directorate of the Atomic Energy Commission, in Orsay, used oligonucleotides, which enable certain defective cells to synthesize a protein they are lacking or to counteract the effects of a defective protein, whether by preventing its reproduction or disrupting its behavior.

While it is already possible to keep track of the route followed by molecules inside an organism, it can only be done at present with laboratory animals, using long and laborious methods.

This new technique considerably reduces the time for such studies. Once the oligonucleotides are radioisotoped, their passage through the organism can be pinpointed within a few hours. It gives researchers direct access to an image of all the organs in the body and, because it is non-invasive and sensitive, can be used in man without risk, thus reducing the need for animal experiments.

As INSERM points out, the technique could constitute a major methodological advance for the development and validation of gene therapies. *