Forming Magnetosome-Like Nanoparticles in Mammalian Cells for Molecular MRI

To identify molecular activities that define the early stages of disease progression, there is a critical need to noninvasively image these processes. For this, the magnetosome is an ideal structure by which cellular and molecular magnetic resonance imaging (MRI) may be refined. Within the design of this magnetotactic bacterial compartment lies the genetic machinery to fashion versatile and effective gene-based magnetic resonance (MR) contrast in mammalian systems. Review of the current understanding of magnetosome formation indicates that a subset of bacterial genes provides a rudimentary compartment within which iron biomineral synthesis may be tailored. Based on the success of MagA and Mms6 expression in a variety of mammalian cells and tissue, future applications using a combination of magnetosome genes are envisioned, to build magnetosome-like nanoparticles in mammalian cells that will provide distinct MR signatures for reporter gene expression. An estimate of the limits of sensitivity of MRI reporter gene expression based on a magnetosome-like nanoparticle is provided. Such a tool is expected to have broad application, including molecular imaging of iron metabolism and magnetic particle imaging.