Blood vessels exhibit highly regulated barrier function allowing selective passage of macromolecules. And the disorder in barrier function can cause abnormal vascular permeability, which is often associated with various pathological states. There is no realistic in vitro model for measuring vascular permeability because most models are limited to mimicking anatomical structural properties. Here, to study vascular permeability, a method based on the human microvessel-on-a-chip is established at Creative Proteomics to overcome the problem mentioned above and enables the study of compounds that protect the endothelial barrier function.