Dual imaging of pulmonary delivery and gene expression of dry powder inhalant by fluorescence and bioluminescence.

In gene therapy with an inhalant, therapeutic outcome depends on both the pulmonary delivery of the agent and the gene expression properties in the lung. The aim of the present study was to visualize and evaluate both the pulmonary delivery and the gene expression properties of a dry powder at once in mice. We used indocyanine green (ICG) as a fluorescent label, the plasmid DNA pCMV-Luc encoding the firefly luciferase as a reporter, chitosan as a non-viral vector and lactose as a carrier of the dry powder prepared by a supercritical carbon dioxide process. The pulmonary delivery of the dry powder and the gene expression in the lung were evaluated by detection of fluorescence of ICG and the detection of luciferase activity, respectively, by using a real-time in vivo imaging system (IVIS imaging system, Xenogen Corporation). The fluorescence and bioluminescence were more specifically detected by measuring from the back of the mice. We succeeded in visualizing both the pulmonary delivery and the gene expression in the same mouse that correlated with each other. In conclusion, the dry powder containing both ICG and pCMV-Luc was useful as a dual imaging system to visualize pulmonary delivery and gene expression in mice.