In vivo magnetic resonance imaging of iron oxide-labeled, arterially-injected mesenchymal stem cells in kidneys of rats with acute ischemic kidney injury:: Detection and monitoring at 3T

Purpose: To evaluate MRI for a qualitative and quantitative in vivo tracking of intraaortal injected iron oxide-labeled mesenchymal stem cells (MSC) into rats with acute kidney injury (AKI). Materials and Methods: In vitro MRI and R-2* measurement of nonlabeled and superparamagnetic iron oxide (SPIO)-labeled MSC (MSCSPIO) was performed in correlation, to cellular iron content and cytological examination (Prussian blue, electron microscopy). In vivo MRI and R2* evaluation were performed before and after ischemic/reperfusion AKI (N = 14) and intraaortal injection of 1.5 X 10(6) MSCSPIO (N = 7), fetal calf serum (FCS) (medium, N = 6), and SPIO alone (N = 1) up to 14 days using a clinical 3T scanner. Signal to noise ratios (SNR), R2* of kidneys, liver, spleen, and bone marrow, renal function (creatinine [CREA], blood urea nitrogen [BUN)), and kidney volume were measured and tested for statistical significance (Student's t-test, P < 0.05) in comparison histology (hematoxylin and eosin [H&E], Prussian blue, periodic acid-Schiff [PAS], CD68). Results: In vitro, MSCSPIO showed a reduction of SNR and T-2* with R-2* approximate to number of MSCSPIO) (R-2 = 0.98). In vivo MSCspIo administration resulted in a SNR decrease (35 +/- 15%) and R-2* increase (101 +/- 18.3%) in renal cortex caused by MSCSPIO accumulation in contrast to control animals, (P < 0.01). Liver, spleen, and bone marrow (MSCSPIO) showed a delayed SNR decline/R-2* increase (P < from MSCSPIO migration. The increase of kidney volume and the decrease in renal function (P < 0.05) was reduced in MSC-treated animals. Conclusion: Qualitative and quantitative in vivo cell-tracking and monitoring of organ distribution of intraaortal injected MSCSPIO in AKI is feasible in MRI at 3T.