Analysis of Vascular Permeability by a Modified Miles Assay

The endothelial barrier is a semipermeable cell layer covering the inside of blood vessels that regulates the flux of ions, macromolecules, and plasma from blood to tissues. Inflammation promotes an increase in vascular permeability, which can contribute to disease if not controlled properly. Thus, it is important to understand in detail the molecular mechanisms underlying inflammatory vascular hyperpermeability. While endothelial permeability can be measured in vitro, these assays do not recapitulate precisely the in vivo vasculature. Thus, in vivo assays are required to understand the full picture of vascular permeability regulation. Here, we describe an established assay that involves injection of Evans blue dye followed by intradermal injection of agents inducing vascular permeability. This assay is relatively easy to perform and provides reliable data on permeability regulation in vivo. Key features • Step-by-step protocol to study vascular permeability in the mouse skin. • Injection of Evans blue dye followed by intradermal injection of permeability-inducing agents allows reproducible analysis of regulatory mechanisms. • This protocol allows the analysis of different substances in the same animal. • Possibility of different dye administration routes that can be compared.