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Imaging of Gene Expression in Live Pancreatic Islet Cell Lines Using Dual-Isotope SPECT

2007; Society of Nuclear Medicine and Molecular Imaging; Volume: 49; Issue: 1 Linguagem: Inglês

10.2967/jnumed.107.043430

1535-5667

Joo Ho Tai, Binh Nguyen, R. Glenn Wells, Michael S. Kovacs, Rebecca McGirr, Frank S. Prato, Timothy G. Morgan, Savita Dhanvantari,

Congenital heart defects research

We are combining nuclear medicine with molecular biology to establish a sensitive, quantitative, and tomographic method with which to detect gene expression in pancreatic islet cells in vivo. Dual-isotope SPECT can be used to image multiple molecular events simultaneously, and coregistration of SPECT and CT images enables visualization of reporter gene expression in the correct anatomic context. We have engineered pancreatic islet cell lines for imaging with SPECT/CT after transplantation under the kidney capsule. Methods: INS-1 832/13 and αTC1-6 cells were stably transfected with a herpes simplex virus type 1−thymidine kinase−green fluoresecent protein (HSV1-thymidine kinase-GFP) fusion construct (tkgfp). After clonal selection, radiolabel uptake was determined by incubation with 5- 131 I-iodo-1-(2-deoxy-2-fluoro-β-d-arabinofuranosyl)uracil ( 131 I-FIAU) (αTC1-6 cells) or 123 I-FIAU (INS-1 832/13 cells). For the first set of in vivo experiments, SPECT was conducted after αTC1-6/tkgfp cells had been labeled with either 131 I-FIAU or 111 In-tropolone and transplanted under the left kidney capsule of CD1 mice. Reconstructed SPECT images were coregistered to CT. In a second study using simultaneous acquisition dual-isotope SPECT, INS-1 832/13 clone 9 cells were labeled with 111 In-tropolone before transplantation. Mice were then systemically administered 123 I-FIAU and data for both 131 I and 111 In were acquired simultaneously. Results: αTC1-6/tkgfp cells showed a 15-fold greater uptake of 131 I-FIAU, and INS-1/tkgfp cells showed a 12-fold greater uptake of 123 I-FIAU, compared with that of wild-type cells. After transplantation under the kidney capsule, both reporter gene expression and location of cells could be visualized in vivo with dual-isotope SPECT. Immunohistochemistry confirmed the presence of glucagon- and insulin-positive cells at the site of transplantation. Conclusion: Dual-isotope SPECT is a promising method to detect gene expression in and location of transplanted pancreatic cells in vivo.