Mol Imaging Biol. 2015 Apr;17(2):185-94.
Optimization of Mesenchymal Stem Cells (MSCs) Delivery Dose and Route in Mice with Acute Liver Injury by Bioluminescence Imaging
Zhengran Li1, Xiaojun Hu1, Junjie Mao1, Xuelian Liu1, Lina Zhang1, Jingjing Liu1, Dan Li1, Hong Shan1, 2
1Department of Radiology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510630, China
2Interventional Radiology Institute, Sun Yat-sen University, Guangzhou, 510630, China
Purpose: Both experimental and initial clinical studies have shown the therapeutic potential of mesenchymal stem cells (MSCs) in liver disease. Noninvasive tracking of MSCs could facilitate its clinical translation. The purpose of this study was to optimize MSCs delivery dose and route in mice with acute liver injury using bioluminescence imaging (BLI) to track the cells.
Procedures: MSCs were labeled with the Luc2-mKate2 dual-fusion reporter gene (MSCs-R). The fate of MSCs-R was tracked through in vivo BLI after administration of different doses or delivery through different routes.
Results: When delivered via the superior mesenteric vein (SMV), the high-dose (1.0×106 and 5.0×105) group mice demonstrated high liver BLI signal but also had lethal portal vein embolization (PVE). By contrast, no PVE and its related death occurred in the low-dose (2.5×105) group mice. Thus, 2.5×105 is the optimal delivery dose. Three delivery routes, i.e., inferior vena cava (IVC), SMV, and intrahepatic (IH) injection, were also systematically compared. After IVC infusion, MSCs-R were quickly trapped inside the lungs, and no detectable homing to the liver and other organs was observed. By IH injection, lung entrapment was bypassed, but MSCs-R distribution was only localized in the injection region of the liver. By contrast, after SMV infusion, MSCs-R were dispersedly distributed and stayed as long as 7-day posttransplantation in the liver. The in vivo imaging results were further validated by ex vivo imaging, digital subtraction angiography (DSA), and tissue analysis. Therefore, SMV is the optimal MSCs delivery route for liver disease.
Conclusions: Collectively, BLI, which could dynamically and quantitatively track cellular location and survival, is useful in determining MSCs transplantation parameters.
Key words: Mesenchymal stem cells, Liver disease, Delivery dose, Delivery route, Bioluminescence imaging
Molecular imaging is a useful tool for stem cell tracking (1). It allows us to investigate cellular behavior of transplanted stem cells in a noninvasive and real-time way. When cells are labelled transiently, the imaging reporter genes (2) or contrast agents (3) are diluted during cell division. Therefore, cell survival and proliferation can’t be accurately assessed. To solve the above-mentioned problem, we stably labelled MSCs with Luc2-mKate2 dual-fusion reporter gene using lentiviral vectors. Luc2 (luciferase reporter gene) and mKate2 (fluorescent reporter gene) were used for in vivo BLI and ex vivo tissue analysis, respectively. In mice with acute liver injury, cellular fate (distribution, localization, survival, and proliferation) were dynamically tracked and the optimal delivery dose and route (Figure 1) were determined.
Figure 1. In vivo BLI of acute liver injury model nude mice after MSCs transplantation via three different routes, including inferior vena cava ( IVC ), SMV, and intrahepatic ( IH ) injection.
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Acknowledgements: This work was supported by the National Natural Science Foundation of China (No. U1032002, 81271621, 81301266, 81101096) and Key Clinical Research Project of Public Health Ministry of China 2010 – 2012 (No. 164).