Magnetic nanoparticles as markers for cellular MR imaging

Cellular MR imaging is a rapidly growing field that aims to visualize targeted cells in living organisms. Superparamagnetic iron oxide nanoparticles, that induce a hypointense contrast on the MR images, have now widely been used to mark cells in vitro and in vivo. Following intravenous injection, the particles are rapidly taken up by phagocytic cells of the reticuloendothelial system, and imaging of this macrophage activity has been translated into the clinic for tumor staging of the liver and lymph nodes. A new, still experimental application of magnetic particles as cellular markers is its use to monitor cell migration and cell trafficking following labeling and transfer to living organisms. Further exploitation of this technique will allow a better understanding of the dynamics of in vivo cell biology as well as translation into the clinic to monitor (stem) cell-based therapies. (c) 2004 Elsevier B.V. All rights reserved.