In Vivo Visualizing The Transplanted Stem Cells:A Combination Of Exogenous NIR-? Flurescence And Endogenous Bioluminescence Imaging

Objects:Development a dual-labeling strategy to in situ visualize the death and survival of transplanted stem cells in vivo by combining the Ag2S QDs-based near-infrared fluorescence imaging and red firefly luciferase-based bioluminescence imaging.Methods:The RfLuc gene was amplified from pCMV-red firefly Luc vector by polymerase chain reaction(PCR)and cloned into the adenoviral shuttle vector(pTrack-CMV).Then the pTrack-RfLuc and the adenoviral backbone vector(pAdeasy)were homologous recombined in BJ5183 cells.The adenovirus were produced using AD-293 cells and purified by a sucrose gradient ultracentrifugation approach.Then,a dual-labeling strategy was studied to label mMSCs with Ag2S QDs and RfLuc.After that,a systematical analyses were performed to test the biocompability of the dual-labeling strategy.Mice with acute liver failure were induced by intraperitoneal injection of 0.1%CC14.The dual-labeled mMSCs were intravenously injected into the mice with acute liver failure.The BLI images and NIR-II fluorescence images were obtained after cell transplantation.The therapeutic potential of dual-labeled mMSCs for liver regeneration was performed by AST and ALT assay,liver histology assay,and immunofluorescence assay.Results:A dual-labeling strategy was successfully developed to label mMSCs with RfLuc(620 nm)and Ag2S QDs(1200 nm).A systematical cytotoxicity study suggested the high biocompability of the dual-labeling strategy with no adverse effects on cell viability,proliferation,osteogenic and adipogenic differentiation.Then,a multi-model imaging was developed to in vivo visualize the death and survival of transplanted stem cells by combining the exogeneous near-infrared fluorescence in the second window(NIR-II)and edogeneous bioluminescence imaging(BLI).It was found that the the dual-labeled mMSCs could be imaged by both IVIS Lumina II system and NIR in vivo imaging system with a detection sensitivity of 100 or 1000 cells respectively.The dynamic translocation,death and survival of intravenously transplanted cells were systematically imaged and semi-quantified by using the combined NIR-II PL imaging and BLI method in mice with acute liver failure,It was found that the death of MSCs occured at the early stage of cell transplantation.Moreover,only 4.48%of live MSCs could be accumulated in the liver 24 h after transplantation.In combination with the liver regeneration assay,the results suggested that the paracrine effects of MSCs at the early stage of transplantation,as well as the adult liver progenitor cells(LPSs)stimulated by the mesenchymal cells in the liver,promoted liver regeneration.Conclusions:We have developed a combined dual-labeled BLI/NIR-II strategy for dynamic monitoring cell translocation,death and survival in vivo with desirable spatial resolution and sensitivity.With the biocompatible nature of the dual-label system,we expect that it will have great promises in a broad range of biomedicine and stem cell studies,such as imaging-guided cell therapeutics,drug screening,and so on.