Parker H. Mills1,2, Thomas Link3, Aravind Arepally3, Joseph D. Thompson4, Jeff W.M. Bulte3, Eric T. Ahrens1,2
1Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA; 2Pittsburgh NMR Center for Biomedical Research, Pittsburgh, PA, USA; 3Institute for Cell Engineering, Johns Hopkins School of Medicine, Baltimore, MD, USA; 4Division of Materials Science & Technology, Group 10, Los Alamos National Laboratory, Los Alamos, NM, USA
Non-invasive studies have monitored the delivery and engraftment of pancreatic islets encapsulated in alginate shells containing Feridex, an FDA-approved superparamagnetic iron-oxide (SPIO). These magnetocapsules are permeable to metabolites, but not native antibodies, thus reducing or avoiding immunosuppressive therapy. Here we apply a newly developed post-processing method, Phase map cross-correlation Detection and Quantification (PDQ), to gel phantoms containing ~103, 450 μm diameter magnetocapsules. PDQ automatically identified and counted magnetocapsules, accurately measuring their magnetic moment (within 1-21% of SQUID-measured values). PDQ can potentially search tissue volumes for absolute magnetocapsule numbers, providing insight on overall islet immunoprotection and survival. PDQ requires no special pulse sequences and works on previously-acquired data.