Compatibility of superparamagnetic iron oxide nanoparticle labeling for ¹H MRI cell tracking with ³¹P MRS for bioenergetic measurements

Labeling of cells with superparamagnetic iron oxide nanoparticles permits cell tracking by ¹H MRI while ³¹P MRS allows non-invasive evaluation of cellular bioenergetics. We evaluated the compatibility of these two techniques by obtaining ³¹P NMR spectra of iron-labeled and unlabeled immobilized C2C12 myoblast cells in vitro. Broadened but usable ³¹P spectra were obtained and peak area ratios of resonances corresponding to intracellular metabolites showed no significant differences between labeled and unlabeled cell populations. We conclude that ³¹P NMR spectra can be obtained from cells labeled with sufficient iron to permit visualization by ¹H imaging protocols and that these spectra have sufficient quality to be used to assess metabolic status. This result introduces the possibility of using localized ³¹P MRS to evaluate the viability of iron-labeled therapeutic cells as well as surrounding host tissue in vivo. Published in 2010 by John Wiley & Sons, Ltd.