Geralda A. F. van Tilborg1, David P.
Cormode2, Peter A. Jarzyna2, Annette van Der Toorn1,
Susanne M. A. van Der Pol3, Louis van Bloois4, Gert
Storm4, Willem J. M. Mulder2, Helga E. de Vries3,
Rick M. Dijkhuizen1
1Image Sciences Institute,
University Medical Center Utrecht, Utrecht, Netherlands; 2Translational
& Molecular Imaging Institute, Mount Sinai School of Medicine, New York,
United States; 33Department of Molecular Cell Biology &
Immunology, VU University Medical Center, Amsterdam, Netherlands; 4Department
of Pharmaceutics, Institute for Pharmaceutical Sciences, Utrecht, Netherlands
MRI-based in vivo cell tracking studies require potent and biocompatible contrast agents with high labeling efficiency, and, preferentially, inclusion of fluorescent entities for additional microscopic analyses. In the present study we compared three different types of fluorescent lipid-coated nanoclusters of iron oxide, with or without inclusion of an oil phase. Nanoparticles without oil showed superior properties in terms of relaxivity r2, shelf-life, labeling efficiency of murine macrophages and biocompatibility. In conclusion, lipid-coated nanoclusters of iron oxide represent an attractive, potent and flexible platform with, in the absence of an oil phase, excellent properties for cellular imaging.