Stacey Marie Cromer Berman1,2, Assaf A. Gilad1,2, Jeff W. M. Bulte1,2, Piotr Walczak1,2
1Russell H. Morgan Dept. of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD, United States; 2Cellular Imaging Section, Vascular Biology Program, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
One important obstacle for correct interpretation of long-term MRI cell tracking is the possibility of persisting hypointense signal even after death of transplanted cells. In order to evaluate this challenge, SPIO-labeled neural stem cells were allografted into the brains of immunocompetent Balb/C mice, inducing cell rejection (dead cells) and immunodeficient Rag2 mice, with no cell rejection (live cells). The transplanted cells were monitored in vivo by MRI for 93 days. Unexpectedly, the MR hypointensities cleared more rapidly in non-rejecting Rag2 mice than in rejecting Balb/C mice, indicating that cell proliferation and migration may dominate clearance of MR signal.