Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Medical Biophysics

Supervisor

Donna Goldhawk

2nd Supervisor

Lisa Hoffman

Joint Supervisor

Abstract

Magnetic resonance imaging (MRI) is one of the non-invasive imaging modalities used in longitudinal cell tracking. Previous studies suggest that MagA, a putative iron transport protein from magnetotactic bacteria, is a useful gene-based magnetic resonance contrast agent. Hemagglutinin (HA)-tagged MagA was stably expressed in undifferentiated embryonic mouse teratocarcinoma, multipotent P19 stem cells to provide a suitable model for tracking these cells during differentiation. Western blot and immunocytochemistry confirmed the expression and membrane localization of MagA-HA in P19 cells. Elemental iron analysis using inductively-coupled plasma mass spectrometry revealed significant iron uptake in both parental and MagA-HA-expressing P19 cells, cultured in the presence of iron-supplemented medium. Withdrawal of this extracellular iron supplement revealed unexpected iron export activity in P19 cells, which MagA-HA expression attenuated. The influence of iron supplementation on parental and MagA-HA-expressing cells was not reflected by longitudinal relaxation rates. Measurement of transverse relaxation rates (R2* and R2) reflected changes in total cellular iron content. In particular, the reversible component R2′ (R2* ‒ R2) provided a moderately strong correlation to amount of cellular iron, normalized to amount of protein.


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