Endothelial cell FGF signaling is required for injury response but not for vascular homeostasis.

Endothelial cells (ECs) express fibroblast growth factor receptors (FGFRs) and are exquisitely sensitive to FGF signals. However, whether the EC or another vascular cell type requires FGF signaling during development, homeostasis, and response to injury is not known. Here, we show that Flk1-Cre or Tie2-Cre mediated deletion of FGFR1 and FGFR2 {Fgfr½Flk1-Cre or FgfrV 2tie2-cre mice), which results in deletion in endothelial and hematopoietic cells, is compatible with normal embryonic development. As adults, Fgfr½Flk-1-Cre mice maintain normal blood pressure and vascular reactivity and integrity under homeostatic conditions. However, neovascularization after skin or eye injury was significantly impaired in both Fgfr½Flk-1-Cre and Fgfr½½Flk-1-CreTie2-Cre½Flk-1-Cre mice, independent of either hematopoietic cell loss of FGFR½ or vascular endothelial growth factor receptor 2 (Vegfr2) haploinsuf-ficiency. Also, impaired neovascularization was associated with delayed cutaneous wound healing. These findings reveal a key requirement for cell-autonomous EC FGFR signaling in injury-induced angiogenesis, but not for vascular homeostasis, identifying the EC FGFR signaling pathway as a target for diseases associated with aberrant vascular proliferation, such as age-related macular degeneration, and for modulating wound healing without the potential toxicity associated with direct manipulation of systemic FGF or VEGF activity. [ABSTRACT FROM AUTHOR]