In Vivo MR Imaging of Magnetically Labeled Mesenchymal Stem Cells in a Rat Model of Renal Ischemia

ABSTRACT

OBJECTIVE: This study was designed to evaluate in vivo MR imaging for the depiction of intraarterially injected superparamagnetic iron oxide (SPIO)-labeled mesenchymal stem cells (MSCs) in an experimental rat model of renal ischemia. MATERIALS AND METHODS: Left renal ischemia was induced in 12 male Sprague-Dawley rats by use of the catheter lodging method. In vivo MR signal intensity variations depicted on T2*-weighted sequences were evaluated in both the left and right kidneys prior to injection (n = 2), two hours (n = 4), 15 hours (n = 2), 30 hours (n = 2) and 72 hours (n = 2) after injection of SPIO-labeled MSCs in both kidneys. Signal intensity variations were correlated with the number of Prussian blue stain-positive cells as visualized in histological specimens. RESULTS: In an in vivo study, it was determined that there was a significant difference in signal intensity variation for both the left and right cortex (40.8 +/- 4.12 and 26.4 +/- 7.92, respectively) and for both the left and right medulla (23.2 +/- 3.32 and 15.2 +/- 3.31, respectively) until two hours after injection (p < 0.05). In addition, signal intensity variation in the left renal cortex was well correlated with the number of Prussian blue stain-positive cells per high power field (r = 0.98, p < 0.05). CONCLUSION: Intraarterial injected SPIO-labeled MSCs in an experimental rat model of renal ischemia can be detected with the use of in vivo MR imaging immediately after injection.