Multimodal molecular imaging system for pathway-specific reporter gene expression.

Preclinical imaging modalities represent an essential tool to develop a modern and translational biomedical research. To date, Optical Imaging (OI) and Magnetic Resonance Imaging (MRI) are used principally in separate studies for molecular imaging studies. We decided to combine OI and MRI together through the development of a lentiviral vector to monitor the Wnt pathway response to Lithium Chloride (LiCl) treatment. The construct was stably infected in glioblastoma cells and, after intracranial transplantation in mice, serial MRI and OI imaging sessions were performed to detect human ferritin heavy chain protein (hFTH) and firefly luciferase enzyme (FLuc) respectively. The system allowed also ex vivo analysis using a constitutive fluorescence protein expression. In mice, LiCl administration has shown significantly increment of luminescence signal and a lower signal of T2 values (P<0.05), recorded noninvasively with OI and a 7 Tesla MRI scanner. This study indicates that OI and MRI can be performed in a single in vivo experiment, providing an in vivo proof-of-concept for drug discovery projects in preclinical phase.