Observational evidence from the literature has shown an association between migraine headaches and patent foramen ovale (PFO). This observation has led to hypotheses that could explain the etiology of migraines in those with a PFO, including right-to-left shunting of venous agents such as serotonin that are normally broken down in the pulmonary circulation. Further evidence suggests that closure of a PFO may improve migraine symptoms and serve as an effective treatment modality for migraines. Several randomized controlled double-blinded studies are underway that will more definitively establish the role of specific devices in PFO closure in those suffering from migraines.

BACKGROUND: Intramyocardial transplantation of stem cells improves left ventricular ejection fraction (EF) in animal studies and preliminary clinical trials. The mechanism may involve either replacement of myocytes or improved vascular supply to existing myocytes. We recently identified an Embyronic Stem cell derived cardiovascular progenitor cell (ES-CPC) that is the common precursor of cardiomyocyte and vascular cell lineages. To determine whether myocyte transplantation improves myocardial function more than angiogenesis alone does, we compared the effect of ES-CPCs to hemangioblasts (vascular/hematopoetic progenitor cells) on EF in a mouse model of myocardial infarction. METHODS: ES-CPC and hemangioblasts were isolated from a doxycycline-responsive, Notch-inducible ES cell line containing Notch 4 cDNA under the control of a tetracycline-inducible promoter. Notch induction of mesoderm-derived ES cells resulted in a CPC phenotype, whereas non-induced cells developed into hemangioblasts. Mice underwent transplantation of 500,000 ES-CPC (n=20), hemangioblasts (n=16), or an equal volume of serum-free media (n=12) 30 minutes after surgically-induced myocardial infarction. All cell lines constitutively expressed green fluorescent protein (GFP). EF was assessed two weeks post-transplantation using 9.4 Tesla MRI. Mice were then euthanized and frozen heart sections were examined using fluorescent microscopy. RESULTS: The mean EF was 59Â ± 15, 46Â ± 17, and 39Â ± 13% in the ES-CPC, hemangioblast, and control groups, respectively (p<0.05 for the differences among all 3 groups; ANOVA). GFP + cells were detected in frozen sections of both the ES-CPC and hemangioblast groups. GFP + cells in ES-CPC treated hearts expressed markers associated with both cardiomyocyte and vascular phenotypes, whereas the GFP + cells in the hemangioblast group expressed markers associated with vascular phenotypes. CONCLUSIONS: Both hemangioblast and ES-CPC transplantation improves EF in a mouse model of myocardial infarction, but ES-CPC transplantation was more effective. This suggests that enhancement of myocardial function by transplantation of both cardiomyocyte and vascular phenotypes exceeds that with vascular phenotypes alone.

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.