In vivo imaging of lung inflammation with neutrophil-specific 68Ga nano-radiotracer

In vivo detection and quantification of inflammation is a major goal in molecular imaging. Furthermore, cell-specific detection of inflammation would be a tremendous advantage in the characterization of many diseases. Here, we show how this goal can be achieved through the synergistic combination of nanotechnology and nuclear imaging. One of the most remarkable features of this hybrid approach is the possibility to tailor the pharmacokinetics of the nanomaterial-incorporated biomolecule and radionuclide. A good example of this approach is the covalent binding of a large amount of a neutrophil-specific, hydrophobic peptide on the surface of 68Ga core-doped nanoparticles. This new nano-radiotracer has been used for non-invasive in vivo detection of acute inflammation with very high in vivo labelling efficiency, i.e. a large percentage of labelled neutrophils. Furthermore, we demonstrate that the tracer is neutrophil-specific and yields images of neutrophil recruitment of unprecedented quality. Finally, the nano-radiotracer was successfully detected in chronic inflammation in atherosclerosis-prone ApoE-/- mice after several weeks on a high-fat diet. This study was supported by a grant from the Spanish Ministry for Economy and Competitiveness (MEyC) (grant number: SAF2016-79593-P) and from Carlos III Health Research Institute (grant number: DTS16/00059). We thank Simon Bartlett for editorial assistance and manuscript preparation. The CNIC is supported by the Spanish Ministry of Economy, Industry and Competitiveness (MEIC) and the Pro CNIC Foundation, and is a Severo Ochoa Centre of Excellence (MEIC award SEV-2015-0505). Sí