Magnetic Resonance Imaging Cell-Labeling Methods

Because MRI is noninvasive and offers high spatial resolution, it provides an excellent means for in vivo cell tracking. To be able to track the administered cells by MRI, cells must be manipulated ex vivo by incorporating different MRI contrast agents that do not exhibit toxic effects in labeled cells, enable sufficient threshold detection by MRI, and do not elicit side effects in human recipients. To date, paramagnetic, superparamagnetic, and üorinated MR contrast agents have been used to label different cell types (Arbab et al. 2006a; Gilad et al. 2008; Partlow et al. 2007; Wilhelm and Gazeau 2008). Superparamagnetic iron oxide (SPIO) nanoparticles are extensively used to label cells for in vivo tracking by MRI because they are readily available and biodegradable and have a higher threshold for toxicity (Bulte 2006). In this chapter, different MR contrast agents that are being used to label cells and the different methods that are employed to label cells are discussed. Details of a step-by-step labeling method using ferumoxides and protamine sulfate are also discussed.