In vivo optical imaging technique allows the detection of light generated by bioluminescence (BLI), fluorescence (FLI) and Cerenkov luminescence (CLI) in small living animals (up to the size of rats). Optical imaging offers a very high imaging throughput: up to 5 mice can be imaged simultaneously in a short time.
BLI occurs naturally only in a few animal species (e.g. fireflies, marine polyps) and depends on an enzymatic process. To perform BLI studies on mammalian cells, it is necessary to genetically modify them so that they express the luciferase, and to administrate the luciferase substrate (mostly the luciferine) to the host animal. BLI is the most sensitive and specific imaging method to track cells in vivo. It is very well suited to study tumor growth, anti-tumor treatments and metastasis spread, as well as to monitor stem cell migration.
FLI requires the administration of a fluorescent dye or the expression of a fluorescent protein by cells. Injection of fluorescent probes targeting specific areas or molecules of interest allow for example the study of biomarkers that are overexpressed in pathological situations. However, the depth of tissue penetration of light is limited to a few millimeters when using dyes that fluoresce in the visible light range. To image deeper into the tissue, far-red and near-infrared dyes are necessary. The research on new specific reporters is conducted in collaboration with the Department of General, Organic and Biomedical Chemistry of the Université de Mons.
CLI allow the visualization of light emission from many commonly used isotopes in nuclear imaging modalities. Consequently, it allows the use of clinically approved radiotracers in several mice simultaneously.
We can perform FLI, BLI and CLI 2D in vivo imaging. The most frequently imaged animal is mouse, but other species can be imaged as well. Up to 5 mice can be imaged simultaneously. Applications include:
- Cell tracking, tumor monitoring, detection of metastasis spread
- Detection of inflammation using luminol
- Localization of radiotracers or radio-isotopes by CLI
- Molecular imaging of biomarkers specific for cancer, inflammation, bone metabolism, apoptosis, etc. by FLI using specific fluorescent dyes
- FLI with Indocyanine Green (the only fluorescent compound approved for clinical use by the FDA)
- In vitro evaluation of cells for BLI/FLI
- Ex vivo analysis of the biodistribution of cells/compounds within organs (this allows a more precise localization and a more sensitive detection).
- Isoflurane anesthesia is available and animal body temperature is maintained. Imaging of awake animals is nevertheless possible.
PhotonImager RT from Biospace Lab (France).
1) S. Laurent, L. Vander Elst, C. Galaup, N. Leygue, S. Boutry, C. Picard, R.N. Muller, “Bifunctional Gd(III) and Tb(III) chelates based on a pyridine-bis(iminodiacetate) platform, suitable contrast agents for magnetic resonance and optical imaging”, Contrast Med. Mol. Imaging, 9, 300-312 (2014)
2) Mémoires en sciences biomédicales de l’UMONS : Kris VAN RENTERGHEM,Caractérisation d’un modèle de mélanome de souris par une approche bi-modale de l’imagerie: IRM et bioluminescence (janvier 2014)
3) Mémoires en sciences biomédicales de l’UMONS : Anton KROUGLOV, Imagerie moléculaire de l’apoptose in vivo par des approches optique et de résonance magnétique : validation d’un modèle animal pour le test de produits de contraste spécifiques (janvier 2016)