Gene therapy represents a new paradigm in the treatment of human disease. The future widespread application of gene therapy requires gene expression in the targeted cells or tissue. Gene expression means the successful accomplishment of gene delivery, which is most efficaciously accomplished with a gene-therapy vector. In their December 1995 report, Orkin and Motulsky identified shortcomings in all gene-therapy vectors, including a lack of quantitative assessment of gene transfer and expression . Noninvasive imaging specifically addresses the latter issue and can advance the testing of enhanced gene-therapy vectors by providing information on the in vivo location of vector delivery, as well as the extent and magnitude of gene transfer and expression. In addition, the consequences of the gene expression can be evaluated, such as the production of specific enzymes or metabolites, induction of apoptosis, or measurement of tumor shrinkage. While imaging of gene transfer has not yet been approved for routine human applications, several groups have reported systems for detection of gene transfer in animal models. The purpose of this chapter is to provide an overview of current imaging technologies and their scientific bases, with emphasis on those technologies that are applicable to gene therapy. Finally, the current imaging literature will be reviewed with respect to imaging gene therapy vectors, especially adenoviral (Ad) vectors.
1 Corresponding author. Supported by NIH Grant CA80104.
ADENOVIRAL VECTORS FOR GENE THERAPY Copyright 2002, Elsevier Science (USA). Aii rights reserved.
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