Targeting Diseased Areas using Enzyme-Sensitive Contrast Agents for MRI

Magnetic resonance imaging (MRI) has become a standard modality in clinical diagnosis due to the use of contrast agents, which enable the contrast between healthy tissue and diseased tissue to be increased. However, the agents currently used clinically do not allow the identification of particular pathologies or of the affected area of the body. The recent work of two French teams has brought hope in this area.

The recent research of two CNRS (Centre National de la Recherche Scientifique; Vandoeuvre-lès-Nancy [near Nancy], France) teams from Orleans and Gif-sur-Yvette (Orleans' Centre de Biophysique Moléculaire and the Institut de Chimie des Substances Naturelles in Gif-sur-Yvette [near Paris]) have demonstrated that by using a new class of contrast agents sensitive to enzymes, it is possible to locate the affected part of the body. The molecules act as switches--when they encounter a specific enzyme, this initiates a cascade reaction, leading to the activation of the contrast agent, which then becomes detectable in an MRI image. The systems have two positions--they are "off” in the absence of the enzyme, and "on” if present. Therefore, an image is only received when the contrast agents are activated.

The reactions caused by certain enzymes may be an indication of the state of the cells, and be interpreted as the signature of a given disease process. In the future, detection of enzymes due to these contrast agents should enable clinicians to diagnose a disease with a simple MRI examination. Moreover, the system can be modulated and is potentially applicable to a large variety of enzymes, and, therefore, pathologies.

Understanding the mechanism of these new molecules for medical imaging constitutes a major advance in visualizing molecular processes in vivo, as well as in detecting pathologies.

Founded in 1939 by French governmental decree, CNRS' goals include: to evaluate and carry out all research capable of advancing knowledge and bringing social, cultural, and economic benefits for society; contribute to the application and promotion of research results; develop scientific information and support research training; and participate in the analysis of the national and international scientific climate and its potential for evolution to develop a national policy.


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