Rami Tadros, Bhakti Rawal, Karen Briley-Saebo, David O'Connor, Dan Han, Roger Hajjar, Zahi Fayad, Michael Marin, Peter Faries
The Mount Sinai School of Medicine, New York, NY.
OBJECTIVES: Mesenchymal stem cells (MSC) are being investigated in a porcine abdominal aortic aneurysm (PAAA) model for their repair potential. This study uses MSCs labeled with the MRI contrast agent Ferex to non-invasively evaluate MSC migration in-vivo.
METHODS: MSCs from six pigs were isolated from bone marrow via Ficoll Paque separation and expanded in culture. Using a Lentiviral vector, MSC from all six pigs were labeled with green florescent protein (GFP). MSCs from four of these pigs were labeled with Ferex using Poly-L-Lysine, a cationic transfecting agent. These cells were analyzed for Ferex uptake and viability. Preservation of the MSC phenotype was confirmed using cytometry by detecting positive CD90 signals and negative CD45 and CD117. Transmission electron microscopy established that Ferex particles localized to lysosomes of labeled cells. MSCs were then injected into the PAAA. In-vivo MRI was performed at intervals followed by euthanasia and histologic analysis.
RESULTS: Ferex labeled MSCs were visible at 4, 11, and 15 days using MRI and the signal loss progressed at each study interval representing cellular movement (Figure). MSC migration and localization were confirmed with GNP visualization on fluorescence microscopy and immunohistochemistry. A correlation between in-vivo MRI signals and iron deposition was clearly demonstrated histologically using Perl’s staining.
CONCLUSIONS: Ferex can be used as an in-vivo tracking agent of MSCs in PAAA models.
AUTHOR DISCLOSURES: K. Briley-Saebo, Nothing to disclose; P. Faries, Nothing to disclose; Z. Fayad, Nothing to disclose; R. Hajjar, Nothing to disclose; D. Han, Nothing to disclose; M. Marin, Nothing to disclose; D. O'Connor, Nothing to disclose; B. Rawal, Nothing to disclose; R. Tadros, Nothing to disclose.
Posted April 2012