Efficiency of transfection and localization of superparamagnetic iron oxide particles in neural progenitor cells using two methods

Stem cells represent a potentially revolutionary therapy for neurological pathologies but for which a thorough investigation of cell behavior in the living nervous system has yet to be performed. Contrast-enhanced cell tracking with magnetic resonance imaging can enable this investigation by introducing superparagmagnetic iron oxide (SPIO) particles within the cell membrane. Before magnetically labeled cells can be observed in vivo, it is essential to maximize SPIO transfer into the cell and to fully understand the localization of the contrast agent in mature neural cells. For practical applications, a quantitative evaluation of labeled cells before implantation will allow in vivo assertions. In this study, we present a comparison between two methods for magnetic transfection of neural progenitor cells: the hemmaglutinating virus of Japan envelope (HVJ-E) as a viral vector and a liposomal reagent. We show that HVJ-E is a more efficient vehicle of cell transfection using quantitative evaluation and that the iron content per cell can be predicted using a simple, automated image analysis of stained, labeled cells. Image analysis is also used in this study to show that the contrast agent is distributed in the axon after differentiation, an important aspect of understanding cell tracking in vivo.