In vivo imaging of cell proliferation for a dynamic, whole body, analysis of undesired drug effects

Non-invasive in vivo imaging offers a novel approach to preclinical studies opening the possibility of investigating biological events in the spatio/temporal dimension (e.g. in any district of the body in time). Toxicological analysis may benefit from this novel approach through precise identification of the time and the target organs of toxicity manifestations, and assessment of the reversibility of toxic insults. The current limitation for routine application of this technology is the lack of appropriate surrogate markers for imaging toxicological events. Here, we demonstrate that in vivo imaging of a proliferation marker is capable of measuring the reduction of cell proliferation due to genotoxic/apoptotic agents, γ-rays or anti-neoplastic drugs, or the increased proliferation associated with the inflammatory and regenerative reactions occurring after a toxic insult. A number of tools are currently available for imaging proliferation in preclinical and clinical settings, however our data provide a novel way to translate the evidence of toxic effects obtained in preclinical animal studies, by the direct, non-invasive measure of dividing cells in humans.