Study on MR tracking of magnetically labeled swine mesenchymal stem cells after autologous transplantation into acute injured liver in vivo

Objective To evaluate in vivo tracking of swine mesenchymal stem cells (MSCs) la-beled with super paramagnetic iron oxide (SPIO) in intraportal transplantation by a clinical 1.5T MR.Methods MSCs were isolated from swine and cultured as well as expanded, which were then incuba-ted with SPIO (Feridex I. V.). Prussian blue staining was performed for showing intracelluar irons.To establish a swine model of acute liver necrosis, 0.5 g/kg of D-galactosamine was administrated to 10 pigs. MSCs(labeled cells in six, unlabeled cells in four)were injected into liver via portal veins. MR imaging was performed with a clinical 1.5T MR immediately before and at 6 h, 3 d, 7 d, 14 d after transplantation, respectively. Results Prussian blue staining of SPIO labeled MSCs could be effec-tively labeled and the labeling efficiency was almost 100%. Signal intensity loss in liver by SPIO labe-ling on FFE sequence persisted until 14 days after transplantation. Histological analysis by Prussian blue staining showed homing of labeled MSCs in liver after 14 days, primarily distributing in hepatic sinusoids and liver parenchyma. Conclusion MSCs can be labeled with SPIO in vitro successfully.MRI can monitor magnetically labeled MSCs transplanted into liver. Key words: Stem cell transplantation; Mesenchymal stem cell; Super paramagnetic iron ox-ide; Feridex; Magnetic resonance imaging