Euromedim 2006 :1st European Conference on Molecular Imaging Technology

Luminescent probes for optical in vivo imaging

12 May 2006, 11:00

15m

Palais du Pharo, Marseille

oral S9_S10 Molecular Imaging Molecular Imaging

Speaker

Dr Philippe Rizo

Description

Molecular imaging allows a better insight of biological mechanisms in vivo, such as the follow-up of gene expression, drugs biodistributions, the assessment of therapies, and can be used for a wide variety of applications, such as cancer, cardiovascular diseases, inflammation… If several techniques such as nuclear medicine (SPECT, TEP), molecular resonance imaging (MRI) and X ray computed tomography (CT) already bring information in vivo, the optical range of interactions between light and tissues has started to be fully exploited more recently. The advantages of the optical methods lie in their low cost, low manipulation constraints (no radioactivity), short acquisition times and high sensitivity. As new optical imaging techniques such as bioluminescence and fluorescence tomography emerge and appear as new modalities to assess biological events in small animals, the need for suitable optical probes arises. We will present new molecular probes for fluorescence in vivo imaging of tumours in mice. The core of these probes is constituted by a cyclodecapeptide vector, the RAFT molecule, which has a nearly planar conformation. Both a luminescent reporter for imaging and eventually a drug can be grafted on one face of the RAFT, while the other can be independently functionalized by four biological ligands for tumour targeting1. We chose to use the cRGD peptide that allows targeting of the V3 integrin receptors of the endothelium tumour cells. The imaging function can be a classical fluorescent dye, such as Cy5, or a more sophisticated activatable fluorescent function. For these activatable probes, the fluorescence signal is inhibited until the probe has been internalized in the targeted cells. Image contrast is thus dramatically improved. Examples of specific in vivo imaging of internal tumours in nude mice bearing IGROV1 metastatic nodes (human ovarian cancer) will be presented using the different classical and activatable fluorescent probes as contrast agents. 1. D. Boturyn, J.L. Coll, E. Garanger, M. C. Favrot, P. Dumy, J. Am. Chem. Soc. 2004, 126(18), 5730-5739.