Abstract

Investigating Endothelium Permeability in vitro Under Healthy and Diabetic Conditions

Elisabeth Verpoorte, Professor, Pharmaceutical Analysis, University of Groningen

Microfluidic systems incorporating endothelial cell monolayers were among the earliest examples of organs-on-chips, with examples dating back almost two decades. This was to be expected, as microchannels are an obvious (though perhaps not perfect) mimic for the (micro)vascular system in terms of geometry. Moreover, microchannel-based in vitro systems also allow controlled application of shear stress, a crucial parameter in vivo that dictates endothelium properties. We have worked primarily with human umbilical vein endothelial cell (HUVEC) culture in gelatin-coated glass or PDMS channels, and more recently, with cells cultured on a gelatin substrate. This has allowed us to construct microflow systems to study the permeability of endothelial cell monolayers in diabetes-associated microenvironments, by tracking the transport of fluorescently labelled albumin across these barriers into a gelatin layer underneath. We have observed the appearance of protective effects of cell-extracellular matrix interactions on endothelial cell morphology under shear stress (10 dyn/cm²). More specifically, the endothelial cells maintained their typical cobblestone morphology. In addition, we recorded increased basal permeability values, compared to our results from static experiments, results that aligned well with literature data. We were then able to model a DKD milieu in our endothelium-on-a-chip to test a pharmaceutical compound, finerenone, a mineralocorticoid receptor antagonist (MRA) used in the treatment of diabetic kidney disease patients. We observed a statistically significant improvement in endothelial barrier properties for cells protected by finerenone in comparison to measured barrier permeability in DKD milieu without finerenone.