title: Noninvasive indirect imaging of vascular endothelial growth factor gene expression using bioluminescence imaging in living transgenic mice.
abstract: Vascular endothelial growth factor (VEGF) plays a critical role in the early activation of stromal tissues during wound healing and tumor growth. We report the use of a two-step transcriptional amplification (TSTA) approach to augment the transcriptional activity of the relatively weak VEGF promoter (pVEGF) using firefly luciferase (fl) reporter gene and bioluminescence imaging (BLI). In cell culture, we demonstrate that TSTA-based fl gene expression can be significantly enhanced over the direct one-step system. Using a transgenic mouse model (pVEGF-TSTA-fl), we demonstrate the induction of VEGF gene expression using a wound-healing model and a subcutaneous mammary tumor model. In skin-wounding experiments, pVEGF-induced fl expression in the wound lesion is detected on days 4 and 5 and peaks on days 15-22. Furthermore, the bioluminescence signal shows good correlation with the endogenous VEGF protein levels in the wound tissue (r2 = 0.70). In the mammary tumor model, fl expression is detected on day 3, peaks at day 17, and declines thereafter. These results support the use of noninvasive BLI for the longitudinal monitoring of VEGF induction during wound healing and tumor progression, and this mouse model should find use in various applications in which it is important to noninvasively study VEGF gene expression.
authors.affiliation: The Crump Institute for Molecular Imaging, Los Angeles, California, USA.
authors.forename: Yanling
authors.initials: Y
authors.lastname: Wang
authors.forename: Meera
authors.initials: M
authors.lastname: Iyer
authors.forename: Alexander
authors.initials: A
authors.lastname: Annala
authors.forename: Lily
authors.initials: L
authors.lastname: Wu
authors.forename: Michael
authors.initials: M
authors.lastname: Carey
authors.forename: Sanjiv S
authors.initials: SS
authors.lastname: Gambhir
mesh_terms: D000818:Animals; D015687:Cell Hypoxia / Q000235:genetics; D003035:Cobalt / Q000494:pharmacology; D004195:Disease Models, Animal; D020869:Gene Expression Profiling / Q000379:methods*; D005786:Gene Expression Regulation / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D049409:Luciferases, Firefly; D049449:Luminescence; D051379:Mice; D008822:Mice, Transgenic; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics; D015533:Transcriptional Activation / Q000187:drug effects / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics* / Q000378:metabolism*; D051598:Whole Body Imaging; D014945:Wound Healing / Q000235:genetics
chemical_list: D042461:Vascular Endothelial Growth Factor A; D003035:Cobalt; D049409:Luciferases, Firefly; C018021:cobaltous chloride