Genetic Targeting of Organ-Specific Blood Vessels

Rationale: Organs of the body require vascular networks to supply oxygen and nutrients and maintain physiological function. The blood vessels of different organs are structurally and functionally heterogeneous in nature. To more precisely dissect their distinct in vivo function in individual organs, without potential interference from off-site targets, it is necessary to genetically target them in an organ-specific manner. Objective: To generate a genetic system that targets vascular endothelial cells in an organ- or tissue- specific manner and to exemplify the potential application of intersectional genetics for precise, target-specific gene manipulation in vivo. Methods and Results: We took advantage of two orthogonal recombination systems, Dre-rox and Cre-loxP, to create a genetic targeting system based on intersectional genetics. Using this approach, Cre activity was only detectable in cells that had expressed both Dre and Cre. Applying this new system, we generated a coronary endothelial cell specific Cre ( CoEC-Cre ) and a brain endothelial cell specific Cre ( BEC-Cre ). Through lineage tracing, gene knockout and over-expression experiments, we demonstrated that CoEC-Cre and BEC-Cre efficiently and specifically target blood vessels in the heart and brain, respectively. By deletion of VEGFR2 using BEC-Cre , we showed that VEGF signaling regulates angiogenesis in the central nervous system and also controls the integrity of the blood-brain barrier. Conclusions: We provide two examples to illustrate the use of intersectional genetics for more precise gene targeting in vivo, namely manipulation of genes in blood vessels of the heart and brain. More broadly, this system provides a valuable strategy for tissue-specific gene manipulation that can be widely applied to other fields of biomedical research.