Abstract 1105: Gadofluorine M-Cy 3, a Novel Paramegnetic Contrast Agent for the in vivo and Histolgical Identification of Transplanted Cells.

Abstract

PURPOSE: Gadofluorine M with a fluorescent dye (GdFMCy3) is a lipophilic paramegnetic contrast agent that is readily absorbed by cultured cells. We hypothesized that this agent would be superior to iron oxide based techniques for cell tracking post cell transplantation. METHODS: Embryonic Stem Cell derived cardiac progenitor cells (ES-CPCs) were generated using previously established methods and incubated for 12 hours with 5 mM GdFMCy3, or transfected with iron oxide using published protocols. Cell survival was >95% for cells incubated with both GdFMCy3 and iron. 500,000 cells labelled with GdFMCy3, iron oxide or control (no contrast agent) were directly injected into the myocardium of mice (n=5/group). Mice were scanned over a two week interval post injection at 9.4T using gated T1-weighted sequences (GdFMCy3), T2* weighted GRE sequences (iron oxide) or the positive contrast sequence GRASP (iron oxide). Mice were sacrificed and the hearts sectioned for microscopy. Perl staining and fluorescence microscopy were used to identify iron oxide and GdFMCy3 within the myocardium, respectively. RESULTS: GdFMCy3 labelled cells were successfully identified in vivo at 9.4T (figure panel B). Good correlation between MRI and histology was observed for both cell labels (figure ). Contrast to noise ratios were significantly higher in the GdFMCy3 group relative to the iron oxide group (figure ). CONCLUSIONS: GdFM-Cy3 is readily taken up by stem cells and easily identified by both MRI and fluorescence microscopy. Given its superior contrast to noise ratio GdFM-Cy3 may be an excellent alternative to iron oxide for in vivo detection and tracking of transplanted cells.