Location: Warmwater Aquaculture Research UnitTitle: Invivo monitoring of fetoplacental vegfr2 gene activity in a murine pregnancy model using a vegfr2 -luc reporter gene and bioluminescent imaging Author
Submitted to: Reproductive Biology and Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/16/2011
Publication Date: 4/16/2011
Citation: Greene, J.M., Dunaway, C.W., Bowers, S.D., Rude, B.J., Feugang, J.M., Ryan, P.L. 2011. Invivo monitoring of fetoplacental vegfr2 gene activity in a murine pregnancy model using a vegfr2 -luc reporter gene and bioluminescent imaging. Reproductive Biology and Endocrinology. 9:51. Interpretive Summary: Vascular endothelial growth factor receptor-2 (VEGFR2) plays a pivotal role in angiogenesis (the physiological process involving the growth of new blood vessels from pre-existing vessels) by eliciting vascular growth when bound to powerful pro-angiogenic factors. The objective of this study was to determine the feasibility of monitoring fetal VEGFR2 gene activity using bioluminescent (genes engineered to give off light when activated) imaging. Fetal VEGFR2 gene activity was monitored using a light-emitting gene and bioluminescent (light detecting) imaging during finals part of gestation. Our results demonstrated the feasibility of using bioluminescent imaging to monitor late gestation angiogenic activity under normal and experimental conditions. Additionally, baby mouse VEGFR2 gene activity was monitored for three weeks after birth, allowing continuous monitoring of VEGFR2 activity during the final parts of pregnancy and during the first few weeks of life within the same animals.
Technical Abstract: Vascular endothelial growth factor receptor-2 (VEGFR2) plays a pivotal role in angiogenesis by eliciting vascular endothelial cell growth when bound to VEGF, a powerful pro-angiogenic ligand. While Vegf and Vegfr2 are expressed throughout gestation, the latter third of gestation in mice is characterized by a marked increase in fetoplacental angiogenesis. Thus, the objective of this study was to determine the feasibility of monitoring fetoplacental Vegfr2 gene activity non-invasively using a Vegfr2-luc reporter transgenic mouse and bioluminescent imaging. Imaging parameters were optimized using two wild-type (WT) females, bearing Vegfr2-luc fetuses. Then, seven WT females, bred to Vegfr2-luc males, were imaged from gestational day (GD) 12 to 18 to determine the usefulness of the Vegfr2-luc mouse as a model for studying fetoplacental Vegfr2 activity during pregnancy. Semi-quantitative RT-PCR of Vegfr2 was also performed on whole fetoplacental units during this time. Additionally, resultant neonates were imaged at postnatal day (PND) 7, 14 and 21 to monitor Vegfr2 activity during post-natal development. Fetoplacental Vegfr2 gene activity was detected as light emissions beginning on GD 12 of gestation and increased throughout the imaging period (P < 0.05), and this paralleled the Vegfr2 mRNA data obtained from RT-PCR analysis. A decline in fetoplacental light emissions was associated with a poor pregnancy outcome in one pregnancy, indicating that this approach has potential use for studies monitoring pregnancy well-being. Additionally, neonatal Vegfr2 activity was detected at PND 7, 14 and 21 but declined with time (P < 0.0001). In utero fetoplacental Vegfr2 gene activity was monitored longitudinally in a quantitative manner using a luciferase reporter gene and bioluminescent imaging during the latter third of gestation. This study demonstrates the feasibility of using the Vegfr2-luc mouse to monitor late gestation fetoplacental angiogenic activity under normal and experimental conditions. Additionally, neonatal Vegfr2 gene activity was monitored for three weeks postpartum, allowing continuous monitoring of Vegfr2 activity during the latter third of gestation and postnatal development within the same animals.