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.