Pre-determined macromolecular leakage sites with dynamic properties establish endothelial intra-vessel heterogeneity

Endothelial cells display heterogeneous properties based on location and function. How this heterogeneity influences endothelial barrier stability both between and within vessel subtypes is unexplored. We find here that endothelial cells exhibit heterogeneous barrier properties on inter-organ and intra-vessel levels. Using intravital microscopy and sequential stimulation of the ear dermis with vascular endothelial growth factor-A and/or histamine, we observe distinct, reappearing sites, common for both agonists, where leakage preferentially takes place. Further, through repetitive stimulation of the diaphragm and trachea, we find inter-organ conservation of such leakage sites. Qualitatively, pre-determined sites display distinct leakage properties and enhanced barrier breakdown compared to less susceptible regions. Mechanistically, pre-determined sites exhibit lower laminin 5 deposition, which correlates with reduced junctional vascular endothelial (VE)-Cadherin. These data thus highlight functional intra-vessel heterogeneity that defines pre-determined sites which display distinct leakage properties and which may have great impact on pathological vascular leakage and drug delivery.