MR tracking of magnetically labeled mesenchymal stem cells in rats with liver fibrosis

Purpose: In vivo magnetic resonance (MR) tracking of magnetically labeled bone marrow mesenchymal stem cells (BMSCs) administered via the mesenteric vein to rats with liver fibrosis. Materials and Methods: Rat BMSCs were labeled with superparamagnetic iron oxide (SPIO) and the characteristics of the BMSCs after labeling were investigated. Eighteen rats with CCL4-induced liver fibrosis were randomized to three groups to receive SPIO-labeled BMSCs (BMSC-labeled group), cell-free SPIO (SPIO group), or unlabeled BMSCs (control group). MR imaging of the liver was performed at different time points, and signal-to-noise ratio (SNR) of the liver was measured. In vivo distribution of delivered BMSCs was assessed by histological analysis. Results: Labeling of BMSCs with SPIO did not significantly alter cell viability and proliferation activity. In BMSC-labeled group, the liver SNR immediately decreased from 8.56 +/- 0.26 to 3.53 +/- 0.41 at I h post injection and remained at a significantly lower level till 12 days (P<.05 versus the level before). By contrast, the liver SNR of the SPIO group almost recovered to the preinjection level (P=.125) at 3 days after a transient decrease. In control group, the liver SNR demonstrated no significant difference at the tested time points. Additionally, Prussian blue-positive cells were mainly distributed in the liver parenchyma, especially in injured areas. Conclusion: The magnetically labeled BMSCs infused through the mesenteric vein can be detected in the fibrotic liver of rats using in vivo MR imaging up to 12 days after injection. (C) 2010 Elsevier Inc. All rights reserved.