| Background:Molecular imaging is the subject in the cell and molecular level that studys live animals, model systems, and the body's biological processes qualitatively and quantitatively research by vitro imaging detector.In recent years, molecular imaging technology has rapidly developed,which maked it possible for the small animal tumor model to form real-time and non-invasive image in vivo. Compared with traditional detection methods, the optical imaging in the vivo body has great advantages which can be rated as the technological revolution in the field of molecular genetic testing.It introduces fluorescent protein into the target cell or a small animal,and observes biological processes by fluorescence imaging system non-invasivly and dynamicly. This technology is non-radioactive and high sensitive in the detection of tumor micrometastasis,and now it has been widely used in cancer research.The experiment used the red fluorescent protein (DsRed) as the reporter gene By the liposomes 2000 gene transfection method, it labeled mice bladder cancer (BTT739) with the DsRed, established subcutaneous xenograft model of the mouse bladder cancer,and studied by MAESTRO imager the biological process of bladder cancer in vivo non-invasivly and dynamicly.Abstract Objective:To explore molecular fluorescence imaging features of the growth and metastasis of DsRed-marked mouse bladder carcinoma.Methods:The study used lipofectamine 2000 transfection method, transferred on the BTT739 cells with plasmids chickenβ-actin-DsRed-Neo vector.The stably expressing BTT739-DsRed monoclonal cells were got with G418 selection. It randomly divided the 615 mouse of 24 into three groups, injected cell suspension on the hindlimb, the first and second group with BTT739-DsRed cell and the third group with BTT739 cell to found xenograft model. MAESTRO imager recorded fluorescence images of the growth and metastasis of the tumors in vivo and the fluorescence intensity was measured. excitation wavelength was 560-580nm,emission wavelength was 590-610nm, exposure time was 5000ms. After continuous observation of four weeks, every week killed the mouse of the second group and cut into image, made records of the red fluorescent mouse bladder cancer xenograft model, measured the tumor size and fluorescence signal values; analyzed the relations between the tumor size and fluorescence signal values as well as between the whole image and cut image.Result:DsRed tumor could be observed at the first week. Central local fluorescence loss could be detected at the second week, pathologically confirmed necrotic tumor tissue and a little connective tissue. At the forth week, a local lymph node metastasis could be observed with no distant metastasis. The measured values of fluorescent signal were as follows:88.85±17.6,122.26±54.63,133.12±69.06,714.58±342.88counts;the tumor size were as follows:12.78±4.14,45.07±21.7,82.55±28.98,253.01±67.27mm2; The whole body image of tumor size were as follows:11.63±3.27,50.07±23.41,89.76±29.12,289.64±73.56mm2; The cut image of tumor size were as follows:12.24±4.53,72.08±30.12,141.09±43.26,523.89±236.78 mm2; The tumor size and fluorescent signal values reflect positive linear correlation with 0.74coefficient (t=3.97, P< 0.05);whole body imaging and cut image reflect positive linear correlation with 0.97coefficient (t=10, P<0.05).The whole body image of tumor size was 70.85±17.13% of cut image.Conclusion:Red fluorescent mouse bladder cancer xenograft model could observe the growth and metastasis of the tumor intuitivly, continuously, and sensitively. As the tumor increased, the fluorescence range also increased, the fluorescence disappeared after tumor necrosis, the expression of the red fluorescent transferred after the metastasis of the tumor.
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